How to Install Best Management Practices (BMPs) in the Lake Tahoe Basin C

How to Install
Best Management Practices (BMPs)
in the Lake Tahoe Basin
Manual for Building and Landscape Professionals
By the BMP Retrofit Partners
Photo courtesy of J.T. Ravizé 
Bringing the University to You
How to Install
Best Management Practices (BMPs)
in the Lake Tahoe Basin
Manual for Building and Landscape Professionals
Written by:
John Cobourn, Carrie Ann Capp, Scott Cecchi,
Brendan Ferry, Elizabeth Harrison, Jennifer Jespersen, Michael Hogan,
Erik Larson, Molly Pulsifer, Birgit Widegren, and Daryl Witmore
Production Assistance:
The Tahoe Regional Planning Agency
Leslie Allen of The Lake Tahoe Environmental Education Coalition
Heather Segale of the UC Davis Tahoe Environmental Research Center
The Write Type
Workshops Organized and Sponsored by:
The Backyard Conservation Program of:
Nevada Tahoe Conservation District
Tahoe Resource Conservation District
U.S.D.A – Natural Resources Conservation Service
Tahoe Regional Planning Agency’s Erosion Control Team
Lake Tahoe Environmental Education Coalition (LTEEC)
University of Nevada Cooperative Extension
This program is made possible through the generous funding of the following:
California Department of Conservation
California State Water Resources Control Board
Cooperative State Research, Education and Extension Service (CSREES)
Nevada Department of Environmental Protection
Nevada Division of State Lands
U.S. Bureau of Reclamation
U.S. Environmental Protection Agency
The University of Nevada, Reno is an Equal Opportunity/Affirmative Action employer and does not discriminate on the basis of race, color, religion,
sex, age, creed, national origin, veteran status, physical or mental disability, or sexual orientation in any program or activity it operates. The University
of Nevada employs only United States citizens and aliens lawfully authorized to work in the United States.
Chapter 1 ~ Introduction to Lake Tahoe’s BMP Retrofit Program............................ 1
Best Management Practices (BMPs) for water quality: the basics..........................................1
What are priority watersheds?.................................................................................................... 3
How to use this manual............................................................................................................... 3
Information located in this manual............................................................................................ 3
There are agencies to help you................................................................................................. 3
Process to obtain a certificate of BMP completion................................................................. 4
Scheduling your water quality improvements.......................................................................... 5
A note to BMP professionals........................................................................................................ 5
How to Interpret a BMP Site Evaluation Form........................................................................... 5
Soil type......................................................................................................................................... 6
Typical property in Lake Tahoe BEFORE installing BMPs........................................................... 6
Example BMP Site Evaluation Forms........................................................................................... 7
Slow Soil Permeability........................................................................................................... 7
Rapid Soil Permeability......................................................................................................... 8
Typical property in Lake Tahoe AFTER installing BMPs.............................................................. 9
Chapter 2 ~ Temporary BMPs for Construction Sites.............................................. 11
What are temporary BMPs?.......................................................................................................11
What is the difference between erosion and sediment control?.........................................11
Which is the easier and cheaper approach: erosion or sediment control?........................12
When do I need to install temporary BMPs?............................................................................12
What are the maintenance needs of temporary BMPs?.......................................................12
When should I start thinking about BMPs for my construction project?...............................12
What temporary BMPs need to be in place BEFORE I start construction?...........................13
What temporary BMPs do I need to use to prevent sediment from
leaving the construction site?.........................................................................................14
What temporary BMPs do I need to use to prevent erosion from bare, exposed soils?....16
How do I protect spoil piles on my construction site?............................................................16
How do I install temporary BMPs? ............................................................................................16
Always call before you dig........................................................................................................17
Chapter 3 ~ Paved Driveways.................................................................................. 19
Rules & regulations regarding driveways.................................................................................19
Permitting process (required for newly-paved driveways)....................................................20
Conveyance and infiltration......................................................................................................21
Conveyance of runoff on driveways........................................................................................21
A note on berms as conveyance structures on driveways....................................................23
Planning process for paving an unpaved driveway..............................................................25
Driveway paving options...........................................................................................................25
Permeable paving products......................................................................................................26
Unusual circumstances — “problem driveways”....................................................................26
Economies of scale.................................................................................................................... 27
Chapter 4 ~ Runoff and Infiltration........................................................................... 29
Why are infiltration systems needed?...................................................................................... 29
Impervious areas generate runoff............................................................................................ 29
Basic working definitions............................................................................................................ 29
What are infiltration systems?................................................................................................... 30
Maintenance of infiltration systems.......................................................................................... 31
Common types of infiltration systems...................................................................................... 31
Use your soil characteristics to design your infiltration system.............................................. 34
Calculating volumes of runoff.................................................................................................. 34
Different materials can fill subsurface infiltration systems...................................................... 35
Common methods of conveyance to aid infiltration............................................................ 38
Chapter 5 ~ Slope Stabilization................................................................................ 41
Guidelines for stabilizing slopes of various steepness............................................................. 42
Methods for stabilizing slopes greater than 50%..................................................................... 43
Erosion control blankets and geotextiles................................................................................. 45
Chapter 6 ~ Vegetation and Mulch........................................................................ 49
Reasons for creating a vegetated landscape........................................................................50
Steps to a successful revegetation project..............................................................................51
Soil amendments vs. mulch.......................................................................................................52
Mulch depth.........................................................................................................................53
Mulch maintenance...........................................................................................................53
A note on fire safety and defensible space............................................................................54
Pine needle do’s.........................................................................................................................54
Pine needle don’ts......................................................................................................................54
Good watering and lawn care tips . ................................................................................55
Fertilizers, soil amendments........................................................................................................55
Chapter 7 ~ Maintenance and Monitoring............................................................. 57
Basic concepts of BMP maintenance......................................................................................57
Local ordinance requirements .................................................................................................57
Checking BMPs............................................................................................................................58
Plan ahead when installing BMPs for ease of maintenance.................................................58
Maintenance of infiltration and conveyance systems . ........................................................59
Maintenance activities and schedules....................................................................................63
Chapter 8 ~ Permitting.............................................................................................. 65
When are permits needed?.......................................................................................................67
Grading and excavation....................................................................................................67
Residential driveways..........................................................................................................68
Commercial driveways and parking lots..........................................................................69
Glossary...................................................................................................................... 71
A ~Priority Watershed Map.................................................................................................................... A1
B ~ Temporary BMP Hall of Shame.......................................................................................................... B1
C ~ Runoff & Infiltration............................................................................................................................ C1
Soil Permeability Chart 1................................................................................................................... C1
Runoff from Impervious Surfaces Chart 2....................................................................................... C2
D ~ Innovative Slope Stabilization Techniques, Biotechnical Construction...................................... D1
E ~ Tree Removal and Tree Protection on Residential and Commercial Properties
at Lake Tahoe.................................................................................................................................... E1
Sample Tree Removal Application.................................................................................................. E4
F ~ Invasive Weeds in the Tahoe Basin.................................................................................................. F1
Measures to Prevent the Spread of Noxious and Invasive Weeds During Construction
Activities.............................................................................................................................................. F3
G ~Supplemental BMPs for an Integrated Landscape....................................................................... G1
Chapter 1
Introduction to Lake Tahoe’s
BMP Retrofit Program
any homeowners at Lake
engineer and landscape designer, but some
Tahoe have contacted the
homeowners may be able to use it as a do-it-
Tahoe Regional Planning
yourself manual. A more technical publication
Agency (TRPA) and the
with engineered design standards and
Conservation Districts to receive a free Best
Management Practices (BMP) Site Evaluation
specifications is currently under development.
on their properties. Once the homeowner
Best Management Practices
(BMPs) for water quality: the basics
receives the completed BMP Site Evaluation
Before going into the specific details about
in the mail, changes and improvements in the
residential BMPs, the basic terms and rationale
landscape and driveway often need to be
for best management practices will be
and learn which BMPs need to be installed
This manual is intended to help the
Lake Tahoe is suffering from pollution
Storm runoff
landscape designer, contractor, engineer
that comes from human disturbances and
brings a plume
and landscaper interpret the BMP Site
urbanization in the surrounding watershed,
of sediment and
Evaluation and learn how BMPs need to be
also called the Tahoe Basin. This water
designed, installed and maintained in order
pollution is called “non-point source pollution,”
to meet TRPA requirements. The authors
because it comes from many diffuse sources
nutrients into
the lake from a
tributary stream.
have developed this book as a part of the
curriculum of the annual Lake Tahoe BMP
Workshop. The goal is to build the supply of
trained professionals who can implement
BMPs properly. This will in turn make it easier
for property owners to install required BMPs
and qualify for their BMP Certificate of
Completion from TRPA. The primary audience
for this manual is the contractor, architect,
Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program ~ rather than a clearly identifiable point such
lake by an undisturbed watershed is usually
as the waste discharge pipe of a factory or
quite pure, because the watershed’s soils
wastewater treatment plant. In fact, there are
and plants act as a natural water purification
no waste pipes permitted to discharge into
system. The BMP Site Evaluation provides
any water body in the Tahoe Basin.
methods to mimic natural conditions by
The world famous clarity of Lake Tahoe
infiltrating water from rooftops and pavement
has declined considerably over the past 40
(also called impervious coverage) into the
years, and is continuing to decline at the
soil instead of letting it leave the property as
alarming rate of over one foot per year.
Scientists warn that the clarity will be reduced
BMPs are so useful for protecting water
to that of an average lake within 20 to 30
quality that TRPA requires their implementation
years unless we greatly decrease the pollution
on all developed properties in the Tahoe
from our landscapes, roads, and construction
Basin. Some properties in the Lake Tahoe
area require immediate installation of BMPs
The pollutants that do the greatest harm
because they have steeper terrain, more
to Lake Tahoe’s clarity are nutrients and
highly erosive soils and a higher ratio of
fine particles of sediment. According to the
development to undisturbed land. These
recently published Lake Tahoe Watershed
areas are categorized as Priority One
Assessment (USDA, 2000), almost a full
watersheds. Priority One watersheds tend
third of these pollutants result from surface
to have accelerated erosion compared to
water sources, including soil eroding from
other areas in the basin. Property owners in
developed properties. Other sources of
these areas were required to implement BMPs
pollution include atmospheric deposition and
on their property by October 15, 2000, but
ground water. Once in the lake, the nutrients
many still need to complete implementation.
fuel algal growth, and the fine sediments
Required dates for full BMP implementation
remain suspended in the water, reducing its
in Priority Two watersheds and Priority Three
watersheds are shown at right. Please note
Best Management Practices are methods
that the implementation date for properties in
to help developed properties function
Priority Three watersheds, previously scheduled
more like natural, undisturbed forest and
for October 15, 2011, has been changed to
meadowland. Water that is conveyed to a
October 15, 2008.
In many undisturbed
forests, more than 95
percent of rain and
snowmelt soaks into
the ground. Pavement,
rooftops and other hard
surfaces cause water
to run off the surface
rapidly, carrying soil
particles and other
contaminants into
nearby streams and
eventually into the lake.
~ Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program
What are priority watersheds?
by all impervious surfaces with either a
TRPA has created three watershed priorities
naturally vegetated area or an infiltration
based on relative threat to Lake Tahoe. The
system where the runoff can soak into the
required implementation dates are as follows:
soil. Even clean runoff leaving the property
can overload roadside ditches and stream
▀ Priority 1 - October 15th, 2000 (PAST DUE)
▀ Priority 2 - October 15th, 2006
channels, causing erosion and sedimentation
downstream. By infiltrating into the soil, the
▀ Priority 3 - October 15th, 2008
The priority watershed number is entered at
runoff becomes groundwater, and is slowed
the top of the site evaluation report.
way to the lake. Calculations that account
and filtered through the soil profile on its
for specific soil characteristics such as soil
You can also identify which priority watershed
permeability are needed to design infiltration
a property is in by:
systems properly.
▀ Consulting the Watershed Priority Map
(see Appendix A)
Chapters 5 and 6 describe BMPs for Slope
Stabilization and Vegetation and Mulch. If the
▀ Visiting TRPA’s website at: or
property has steep, unvegetated slopes or
▀ Or by contacting one of the agencies
listed below.
to prevent soil erosion and to encourage the
bare soil areas, these areas must be treated
water that falls there to soak into the ground
rather than running off. Slopes of varying
How to use this manual
This manual should be used with a completed
BMP Site Evaluation and the University of
steepness, moisture and soil conditions require
different methods for stabilization.
Chapters 7 and 8 provide additional
Nevada Cooperative Extension’s Home
information regarding BMP installation
Landscaping Guide for Lake Tahoe and
procedures. All BMPs generally require some
Vicinity. The Home Landscaping Guide for
type of maintenance to ensure that the BMPs
Lake Tahoe and Vicinity is a broad reference
installed continue to work effectively. Periodic
guide about conservation which can be used
monitoring ensures that BMPs are treating the
to look up specific topics not covered in this
stormwater runoff to meet the TRPA discharge
manual, such as Defensible Space (Chapter
5 in the Guide) or the TRPA’s recommended
plant list (Chapter 7 of the Guide).
There are agencies to help you
Representatives from five local agencies
Information located in this manual
have formed a coalition in order to help you
The second chapter describes Temporary
implement BMPs on residential properties.
BMPs, which must be installed and maintained
These agencies are listed below:
on all construction sites and during large-
▀ The Nevada Tahoe Conservation District
Please see
▀ The Tahoe Resource Conservation District
for contact
▀ The Natural Resources Conservation
these agencies.
scale BMP retrofit projects. The following two
chapters describe BMPs for Paved Driveways
(Chapter 3) and Runoff and Infiltration
(Chapter 4). The site evaluator will make
recommendations for infiltrating the volume of
runoff that would result from a rainstorm that
produces an inch of rainfall in one hour (the
20-year/1 hour storm). The homeowner must
implement BMPs to treat the runoff generated
back cover
information for
▀ Tahoe Regional Planning Agency’s Erosion
Control Team
▀ The University of Nevada Cooperative
Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program ~ You can call the Nevada Tahoe
Step 1: BMP site evaluation
Conservation District to request a free single-
Property owners should request a free BMP Site
family residential BMP Site Evaluation for
Evaluation by contacting the Nevada Tahoe
your property or that of a client in Nevada.
Conservation District for single-family residence
The Tahoe Resource Conservation District
in Nevada, the Tahoe Resource Conservation
does free single-family residential BMP Site
District for single-family residence in California,
Evaluations for property owners or clients in
and the TRPA Erosion Control Team for
California. Contact TRPA’s Erosion Control
multi-family, commercial or public service
Team for BMP Site Evaluations for commercial,
properties. (See phone numbers, back cover.)
multi-family and public service properties,
Step 2: BMP implementation
and lakeshore/stream environment zone (SEZ)
The property owner will receive a copy of
properties. All five agencies have personnel
the completed BMP Site Evaluation in the
who can assist you with questions about the
mail. Property owners are then responsible to
process or steps that you should follow to
install the BMPs either by doing it themselves,
work toward the end goal of receiving a TRPA
or by hiring a qualified contractor to do the
Certificate of BMP Completion.
work. They can request additional technical
Process to obtain a certificate of
BMP completion
assistance from one of the Conservation
Districts. Property owners may request a list of
contractors who have successfully completed
To bring a property into compliance with the
the Contractor’s BMP Workshop Training.
BMP Retrofit Program and to improve Lake
Step 3: Certificate of completion
Tahoe’s clarity, you can follow these simple
When the BMPs are completed, the contractor
or the property owner should contact TRPA’s
Erosion Control Team for a final inspection. If
An erosion
control expert
a free site
evaluation with
a homeowner.
the BMPs have been installed as prescribed,
the property owner will receive a Certificate
of Completion. This signifies that the property
is in compliance with the TRPA BMP Retrofit
Ordinance. The Certificate will be valid as long
as the BMPs are maintained and functional.
The Tahoe Regional Planning Agency
has been charged by Congress to establish
regulations that will prevent the continued
decline of Tahoe’s water quality. The
requirements for the BMP Retrofit Program are
codified into law in Chapter 25 of the TRPA
Code of Ordinances. Implementation of BMPs
as delineated by a BMP Site Evaluation is
required of all Tahoe Basin landowners to meet
the TRPA BMP Ordinance. Homeowners are
legally required to prevent polluted runoff from
leaving their property.
Within TRPA, the Erosion Control Team has
been formed specifically to help homeowners
meet their BMP requirements. You can call
~ Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program
them or any of the other agencies listed for
Scheduling your water quality
Some homeowners do not want to implement
all BMPs at once due to time and budget
limitations. Determining a BMP implementation
schedule allows flexibility for the homeowner
and allows for phasing of BMP retrofits over
several grading seasons. Use the following
priority list to determine what BMPs should
be implemented first if the project will be
phased over several grading seasons. Be
sure to notify TRPA in writing of your proposed
effective BMPs. Professionals who satisfactorily
BMP implementation schedule to have it
complete these trainings and pass the test will
be listed each year on a list of BMP-trained
Resource Professionals, which will be available
Lake Tahoe.
to property owners. This list states that you
have attended the workshop, but it does not
▀ Vegetate and mulch denuded areas.
▀ Pave legally established roads, driveways
“certify” that you are skilled at implementing
and parking areas.
▀ Stabilize walkways and cut and fill slopes.
See Chapter 2 for temporary BMPs to use
during construction.
A note to BMP professionals
The BMP Retrofit Partners have prepared
this manual specifically to help you take
advantage of a new business opportunity
in the Tahoe Basin. Since thousands of
homeowners will be obtaining BMP Site
Evaluations between now and the final
deadline for Priority Three watersheds in
2008, we want to be sure they can get
professional help to meet the requirements
with a minimum of worry, red tape, and
needless expense. Our partners offer trainings
each Spring to professionals who wish to
become knowledgeable in the design,
implementation and maintenance of
sediment to
The TRPA priority for installation of retrofitting
▀ Install drainage conveyances and Infiltrate
surface water runoff from impervious
Dirt driveways
BMPs, nor does it substitute for a valid
contractor’s license. It is to your advantage
to become very familiar with this manual and
the Home Landscaping Guide for Lake Tahoe
and Vicinity. These resources will enable you to
build the skills necessary to help homeowners
implement BMPs on their property in an
attractive and easy-to-maintain way and
receive their Certificate of BMP Completion.
How to interpret a BMP site
evaluation form
The purpose of this workshop is to teach you
how to use a site evaluation form to install
effective and attractive BMPs on a property in
order to meet TRPA requirements. This section
will familiarize you with the site evaluation
form. Please refer to the sample BMP site
evaluation examples on pages 9 and 10.
BMP site evaluations are drawn up by
agency BMP site evaluators. The evaluation
has a diagram, indicating what BMPs are
required and where they should be located.
Each BMP is assigned a letter of the alphabet
or a number which shows its location(s) on the
Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program ~ site and allows the property owner to find its
description in the table below the diagram.
Soil type
On the BMP site evaluation form, you will find
The chapters of this book describe how each
a soil survey map unit, the permeability of
type of BMP should be designed and installed.
the soil (slow, moderate or rapid), presence
of drainage problems, and average slope
Please note:
percentage and direction. A list of Tahoe’s
Property owners should be aware that a BMP
soil types is presented in Appendix C. Since
site evaluation is NOT a verification of land
one goal of BMPs is to infiltrate stormwater
coverage, land capability or use, nor is it a
runoff into the soil, these factors must be used
conceptual approval of any future project not
to correctly design and size the infiltration
related to the site evaluation.
systems. (See Chapter 4: Runoff & Infiltration.)
A sketch of
a typical
property in Lake
Before implementing BMPs
~ Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program
Site Evaluation with SLOW soil permeability
A sample BMP site evaluation form for the property shown on page 6
illustrating SLOW soil permeability (requires larger drywells).
Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program ~ Site Evaluation with RAPID soil permeability
A sample BMP site evaluation form for the property shown on
page 6 illustrating RAPID soil permeability.
~ Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program
The property on
page 6, after
after implementing BMPs
Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program ~ Notes:
10 ~ Chapter 1: Introduction to Lake Tahoe’s BMP Retrofit Program
Chapter 2
Temporary BMPs for
Construction Sites
hen sediment-laden runoff
are installed. Temporary BMPs must be sized
flows from construction
to control runoff for the 20-year/1-hour storm,
sites and into Lake Tahoe,
which is approximately one inch of rainfall
the nutrients attached to
in an hour in this area. If properly installed,
the sediment spur algal growth. The small
temporary BMPs can prevent the discharge of
or “fine” sediment particles also remain
degraded runoff water from construction sites.
suspended in the lake’s water. Both algae
clarity. Construction sites are especially
What is the difference between
erosion and sediment control?
susceptible to erosion due to the nature of the
Erosion control includes practices that keep
activity, which disturbs large areas of soil and
soil particles in place by protecting them
vegetation, leaving it vulnerable to erosion.
from being eroded by water or wind. In this
Therefore, construction sites are required to
approach, soil is valued as a natural resource
have temporary Best Management Practices
that needs protection. (See photo of mulch
installed BEFORE any disturbance occurs.
and fine sediment reduce Lake Tahoe’s
What are temporary BMPs?
Sediment control includes practices that try
to capture soil particles after they have been
According to the Tahoe Regional Planning
Agency’s Handbook of Best Management
Practices, temporary BMPs are practices
and structures used to prevent or minimize
erosion and sedimentation before and during
construction and until permanent BMPs have
been installed. Temporary BMPs are installed
before the onset of construction and must
be maintained until all construction activity
is completed and/or until permanent BMPs
The 1-2 inch
layer of
pine needle
mulch controls
soil erosion.
Chapter 2: Temporary BMPs for Construction Sites ~ 11
picked up by wind or water. These BMPs
usually try to filter or trap sediment out of the
water or wind. Sediment control does not
treat soil as a natural resource to protect, but
instead emphasizes removing it from runoff,
then redistributing it or disposing of it safely.
(See photo of silt fence and fiber roll log
When do I need to install
temporary BMPs?
Installation of temporary BMPs is required on
all sites where the vegetation and soil will be
disturbed. Temporary BMPs are site-specific,
must be constantly maintained, and are
usually good for only one year or one winter
season. Some of the BMPs named here
are intended for construction that involves
The silt fence
more disturbance than most residential BMP
and fiber roll
implementations will create. However, ANY
log will remove
time soil is disturbed, temporary BMPs are
required to prevent sediment from leaving the
from runoff if
a rainstorm
What are the maintenance needs
of temporary BMPs?
Temporary BMPs require much more
maintenance than permanent BMPs. Due
to their temporary nature, these practices
usually require daily checking, especially
during clearing and grading activities. They
should also be checked immediately before
an impending storm and after the storm has
passed. Sediment that accumulates behind
temporary BMPs must be removed from the
site and disposed of at a TRPA-approved
site upon removal of the BMPs unless TRPA
approves allowing the material to be stabilized
Which is the easier and cheaper
approach: erosion or sediment
When should I start thinking about
BMPs for my construction project?
Erosion control is generally less expensive.
the planning phase of your project. With
Once soil is suspended in water, it is costly
proper planning, disturbance to a construction
and difficult to remove. Also, if you violate
site can be minimized and managed. By
surface water discharge standards, you are
staging your construction process carefully,
liable to pay a fine according to federal, state
you can reduce how much area you disturb.
and local laws. Ultimately, erosion control
Additionally, by phasing stages of your
practices should be “backed-up” by sediment
project, you can disturb less area at one time,
control practices, increasing the protection of
minimizing the threat of serious soil loss.
the construction site.
12 ~ Chapter 2: Temporary BMPs for Construction Sites
You should start thinking about BMPs during
What temporary BMPs need
to be in place BEFORE I start
Temporary Construction Site BMPs
Before you start construction on a project, the
following BMPs need to be properly installed
and must remain in place until all construction
activity is completed and/or until permanent
BMPs are installed:
1. Boundary Fencing is temporary fencing
used on the construction site to mark the limits
of clearing and grading and to define areas
which must be protected. Boundary fencing
is used in order to minimize disturbed areas, to
▄ Use the minimum number of temporary
protect trees and vegetation and to prevent
routes to access the construction site.
▄ Sweep and/or scrape any dirt and
any encroachment in stream environment
fencing around
zones, on steep slopes or in other highly
mud off public streets at the end of the
sites prevents
sensitive areas.
workday, and store sediment onsite with a
vehicles and
2. Traffic Control is the control of onsite traffic
during construction activities, especially
temporary sediment barrier.
▄ Do not allow vehicles to travel over
exposed soils when they are muddy.
during the clearing, grading and excavating
3. Stabilized Construction Entrance consists
construction vehicles can travel must be
of a pad of crushed stone or gravel located
well marked with flagging, markers and/or
at any point where construction traffic enters
temporary fencing before construction activity
or leaves the site. This pad reduces the
begins. This can be combined with boundary
tracking of sediment off of the disturbed site.
fencing. The following guidelines need to be
When necessary, washing of vehicle wheels
to remove sediment before leaving the site
sediment barrier in place to trap water and
sediment. The entrance pad should consist of
slopes and stream zones.
▄ Avoid areas planned as future open
1 to 3 inch diameter, clean, crushed stone or
gravel, at least 8 inches deep. The entrance
must be maintained, which may require
periodic addition of crushed stone or gravel
to the surface. If the construction site already
space to prevent compaction of soils.
has a paved or stabilized entrance that will be
Keep traffic away from wet soils.
used as the only point of ingress and egress,
▄ Clean wheels of construction vehicles
before they leave the construction site.
▄ Create a temporary stabilized
crushed stone pad, with an approved
will be.
where permanent parking areas will be.
▄ Avoid sensitive areas such as steep
will be conducted on this type of stabilized
future roads, driveways, and parking lots
▄ Store materials and park equipment
from damaging
vegetation and
phases of site development. Areas where
▄ Locate construction roads where
or if trucks and other heavy equipment will
not be used onsite, a stabilized construction
entrance is not necessary.
construction entrance and roadway.
Chapter 2: Temporary BMPs for Construction Sites ~ 13
4. Dust Control is the control of wind blown
5. Protection of Trees and Other Vegetation
soil or other materials from construction sites
involves installing temporary fencing or
or soils. Dust control practices are required
other barriers along the dripline of tree and
for all grading activity. There are a variety of
other vegetation’s branches to prevent
methods to control dust, including:
▄ Sprinkle the exposed soil surface with
disturbance to the vegetation itself as well as
the root system. Protective fencing for soil and
water as needed to keep the surface
vegetation must be constructed with metal
moistened to a depth of 2 to 3 inches.
posts, industry standard mesh fencing, and
▄ Mulch the area with 1 to 2 inches of pine
must be at least four feet in height, unless an
▄ Establish a vegetative cover on bare soil
alternative protection method is approved
by TRPA. Boards, wire, rope or other materials
surfaces using native and or adapted
should not be nailed to trees and fill materials
should not be placed next to the trunk of a
Vegetation is the most effective practice to
tree that is designated to be saved. Trees and
stabilize disturbed, bare soils not exposed
other vegetation outside of the grading limits
to construction traffic. Sprinkling is the least
will be protected by the boundary fencing
effective of the practices and has to be
and do not need individual protection.
repeated several times a day. Sprinkling also
need for effective temporary sediment
What temporary BMPs do I need
to use to prevent sediment from
leaving the construction site?
barriers to prevent any sediment-laden water
Temporary sediment barriers are structures
from leaving the site. Please note: Organic
constructed to slow runoff and trap small
mulch (such as pine needles) is required on
amounts of sediment temporarily. Temporary
all denuded soil for the duration of the soil
sediment barriers must be installed around
the downhill perimeter of disturbed soil areas.
increases the probability that soil particles
will be entrained in water, increasing the
Historically, straw bales have been used as
temporary sediment barriers. However, due to
Protective fencing is used to protect the root systems
of trees on construction sites. This fence should be
further from the tree. Vegetation fencing is required to
extend around the full dripline of the tree.
their limited ability to effectively trap sediment
and the danger of noxious weeds being
introduced by their use, they are no longer
recommended for use in the Tahoe Basin.
Instead, use one or more of the temporary
BMPs listed below:
1. Fiber roll barriers (also called sediment logs)
usually consist of milled wood or other natural
fibers sewn into a circular weave fabric. Fiber
rolls are a good perimeter protection BMP,
as long as they are installed properly. Fiber
rolls should be installed on the contour line,
perpendicularly to the slope direction, keyed
into a concave trench at least three inches
deep, and staked securely on both sides of
the roll every twelve inches (see diagram next
page). When two rolls are installed abutting
14 ~ Chapter 2: Temporary BMPs for Construction Sites
each other, the ends should create a tight
but because the fabric bags eventually
joint to prevent sediment from escaping.
rip and sand can leak out and become
a source of sediment, they are no longer
2. Filter Fence consists of a permeable filter
recommended. The gravelbags are stacked
fabric that is keyed into the ground at least
tightly in a U-shape abutting the curb and
6 inches deep, backfilled with dirt or gravel,
intersecting the flow. When installed properly,
and staked along the contour line below the
the bottom of the U-shape is where the
disturbed slope (see diagram above). The
runoff will pool. When the construction runoff
fabric pools the runoff, causing the sediment
is trapped in the U-shape, it slows, ponds,
to be dropped behind the fence while the
and settles out sediment. Gravelbags can
water slowly filters through the fabric. This
also be stacked tightly around drop inlets
BMP is widely used, but unfortunately is often
to prevent sediment from entering the drop
installed improperly and ineffectively (see
inlet. Accumulated sediment trapped behind
the Temporary BMP Hall of Shame in the
the bags needs to be removed often and
appendix for examples.) This BMP should never
disposed of properly. Gravelbags also need
be installed across stream channels or areas
to be inspected often to ensure that they are
of concentrated flow. The ends of the fence
trapping the runoff.
should be installed with a turn uphill to create
a “J” shape that will pond water.
An example of tree protection (fence), fiber roll barriers and
gravelbags on a construction site in the San Francisco Bay Area.
3. Drop inlet barriers prevent sediment and
debris from entering nearby storm water
conveyance systems by slowing runoff and
trapping sediment. Drop inlet barriers are
temporary devices including gravelbags and
drop inlet filters. These devices are intended
for use on a construction area with a curb and
drop inlet system only.
Gravelbags are bags made of a
permeable fabric and filled with clean
(washed) 1 to 3 inch diameter gravel.
Historically, sandbags have also been used,
Chapter 2: Temporary BMPs for Construction Sites ~ 15
Drop Inlet Filters are various proprietary
bio-technical stabilization methods (see
BMPs designed to capture sediment as it
Appendix D). Also, erosion control blankets
enters a drop inlet and filter it out of the runoff.
and geotextiles need to be installed correctly,
They are usually designed to fit inside the drop
which involves stapling them securely to the
inlet itself, attaching in different ways to the
slope and overlapping the materials correctly
inlet and the grate. Drop inlet filters are used
to prevent runoff from undermining the
as a secondary line of protection only, and
material. (See Chapter 5)
do not preclude the need for other required
If you are unfamiliar with the application
temporary BMPs on the construction site.
of chemical mulches, tackifiers, hydromulch
Examples of brands of drop inlet filters include:
and hydroseed, we recommend that you
Fossil Filter, HydroKleen, DrainPac, Ultra-Urban
work with an erosion control specialist until
Filter, and S.I.F.T Filter. Please be aware that
you are familiar with the technical aspects of
TRPA and Cooperative Extension do not
these practices. For more information on slope
endorse any stormwater products.
stabilization, please refer to Chapter 5: Slope
Stabilization. Temporary sediment barriers
What temporary BMPs do I need to
use to prevent erosion from bare,
exposed soils?
should be installed below the area that is
being stabilized by one of these practices.
amount of time must be stabilized by one or
How do I protect spoil piles on my
construction site?
more of the following BMPs:
Spoil piles (piles of excavated soil) that
All bare soil areas that are exposed for any
remain onsite one day or longer need to be
▄ Pine Needle Mulch
▄ Erosion Control Blankets or Geotextiles
▄ Chemical Mulches and Tackifiers
surrounded by properly installed temporary
▄ Hydromulch and hydroseed
impermeable fabric. The impermeable fabric
sediment barriers (fiber rolls or filter fence)
and must be completely covered by an
must also be placed on spoil piles whenever
Each of the different stabilization methods
a storm is impending. This practice will allow
have various technical specifications that
rain to flow off of the fabric instead of allowing
need to be followed to ensure success. For
it to quickly erode the spoil pile. Spoils must
example, pine needle mulch is not effective
be removed from the construction site and
on slopes of more than 3:1, or 33%, without
disposed of at a TRPA-approved site or may
vegetating the slope as well or adding
be stabilized onsite if previously approved by
How do I install temporary BMPs?
Installing temporary BMPs correctly and
maintaining them are the two keys to
successful erosion and sediment control. We
will revisit and demonstrate how to correctly
install various temporary BMPs at the outdoor
This spoils pile should be surrounded by
sediment barriers (fiber roll or filter fence) and
covered completely by plastic sheeting.
16 ~ Chapter 2: Temporary BMPs for Construction Sites
segment of the BMP training. To see how NOT
to install temporary BMPs, please see the
This section does not attempt to discuss all
Temporary BMP Hall of Shame in Appendix B.
temporary BMPs that may be required or
Always call before you dig
appropriate for construction sites, but rather
intends to provide a foundation of basic
Before any excavation, call 1-800-227-2600 to
temporary BMPs that are appropriate in a
get a free site inspection to locate any gas or
wide array of situations. For a full collection of
electric lines beneath the ground surface.
BMPs appropriate in the Tahoe Basin, please
refer to the Water Quality Management
Plan for the Lake Tahoe Region; Volume II:
Construction activity has a high potential to
Handbook of Best Management Practices,
pollute our surface waters and ultimately Lake
available from the Tahoe Regional Planning
Tahoe with sediment and other construction
Agency. Any brand name products
debris. With some forethought and diligence,
mentioned in this chapter are for informational
this type of pollution can be prevented. When
purposes only, as neither Cooperative
in doubt, contact a BMP professional at the
Extension nor TRPA endorse any stormwater
Tahoe Regional Planning Agency’s Erosion
Control Team at 775-588-4547, ext 202, who
will be happy to come out to your site and
Reference documents:
discuss appropriate BMPs for your project with
Erosion and Sediment Control Field Manual,
you. Remember, you are required to prevent
California Regional Water Quality Control
sediment-laden water and wind from leaving
Board, San Francisco Bay Region, 1999.
your construction site and are liable for fines
according to federal, state and local laws
should any runoff leaving your construction site
be in violation of TRPA’s, Lahontan Regional
Water Quality Control Board’s or the State of
Water Quality Management Plan for the Lake
Tahoe Region; Volume II: Handbook of Best
Management Practices, Tahoe Regional
Planning Agency, 1988.
Nevada’s concentration limits. An ounce of
prevention is worth a pound of cure.
Chapter 2: Temporary BMPs for Construction Sites ~ 17
18 ~ Chapter 2: Temporary BMPs for Construction Sites
Chapter 3
Paved Driveways
paved driveway is one of the
that paved area can be used for vehicles.
most effective Best Management
No vehicular disturbance is allowed on
Practices (BMPs) a homeowner
unpaved areas. The use of parking bollards
can implement. Bare soil areas
(i.e. boulders, logs, shrubbery, etc.) is widely
serving as driveways are so compacted
that water cannot readily soak into the
ground. Instead, stormwater will flow off of
encouraged to restrict vehicles to pavement.
TRPA’s Handbook of Best Management
Practices Volume II states, “No private
the compacted soil area and carry sediment
away with it. Also, vehicle tires, snow removal
and other disturbances carry sediment from
unpaved driveways into the street storm drain
system and eventually into Lake Tahoe.
Soil erosion and stormwater runoff can be
controlled with a properly designed paved
driveway. Driveways and infiltration systems
should be designed to preserve natural
vegetation and to blend with the natural
Rules & regulations regarding
The Tahoe Regional Planning Agency’s
(TRPA’s) Code of Ordinances Chapter 25.5.E
states, “All roads, driveways and parking
areas proposed for year-round use shall be
paved.” In other words, any surface designed
for vehicular use must be paved, and only
Parking bollards
are helpful
to prevent
cars from
soil outside the
parking spot.
Chapter 3: Paved Driveways ~ 19
property surface runoff is allowed to flow
For additional driveway and
across public rights-of-way and into the street
encroachment requirements, contact the
storm drain system.” The reason for this rule
local jurisdiction.
is that public stormwater projects are not
from both public and private properties. To
Permitting process (required for
newly-paved driveways)
put it more precisely, all property owners
Generally, prior to paving a driveway, two
are required to infiltrate the volume of a 20-
different permits are required, a Paving Permit
year/1-hour storm, about one inch of rainfall
and an Encroachment Permit from the county
in an hour, on their property, before it runs off
or city in whose jurisdiction the driveway is
to public rights-of-way (the street or ditch).
located. Please contact the county or city that
This can be accomplished in many different
the subject property is located in for additional
ways which will be discussed in detail later in
permitting requirements. You can often obtain
this chapter. The important point is that all
a permit “over the counter” to pave the
driveways should be sloped to convey surface
minimum allowable parking area. See Chapter
runoff to a properly sized infiltration system as
8 for additional information on permitting.
designed to handle the quantity of runoff
described in Chapter 4.
According to Chapter 24.2.C(5) of
As part of the paving permit process, a
BMP site evaluation is required, which is to be
TRPA’s Code of Ordinances, “Slopes of
performed by a staff member from either TRPA,
driveways shall not exceed the standards
NRCS or one of the Conservation Districts. A
of the county or city in whose jurisdiction
legally existing compacted area (See Chapter
the driveway is located. Driveways shall not
8: Permitting), which has been serving as the
exceed ten percent slope, unless TRPA finds
driveway, is considered “soft coverage” by
that construction of a driveway with a ten
TRPA and so may be paved without adding
percent or less slope would require excessive
any additional coverage to the property, since
excavation. The runoff from a steeper
the compacted area is already considered
driveway shall be infiltrated as required in
coverage. For a driveway to be considered
Chapter 25. In no case shall the driveway
legally existing soft coverage, the driveway
exceed fifteen percent slope.”
must have been established pursuant to
According to Chapter 24.2.E(1) of TRPA’s
Chapter 2 of TRPA’s Code of Ordinances.
Code of Ordinances, “Driveways serving
Chapter 2 states, “Soft coverage must have
single family homes shall have a minimum
been used for parking of cars or heavy and
width of ten feet. Where the single family
repeated pedestrian traffic prior to February
home includes a garage, the driveway shall
10, 1972.” Please remember that only the
be at least as wide as the garage door
dimensions of the legally existing soft coverage
opening for a distance of fifteen feet from the
can be paved. Contact TRPA for clarity on the
garage door.”
determination of soft coverage.
For other residential uses, Chapter
If a property already has the maximum
24.2.E(2) of TRPA’s Code of Ordinances states,
allowable coverage designated for that site,
“Two-way driveways serving residential uses
and legally established soft coverage does
other than single family homes shall have a
not exist, findings must be made by TRPA
minimum width of 20 feet and a maximum
to transfer coverage for use as a driveway.
width of 24 feet. One-way driveways serving
Please contact TRPA’s Environmental Review
other residential uses shall have a minimum
Services Branch and the county or city that
width of 10 feet and a maximum width of 12
the subject property is located in to further
investigate establishing a legal driveway.
20 ~ Chapter 3: Paved Driveways
Driveway runoff
is directed
to a slotted
channel drain,
which conveys
water to an
sized system
for storage and
infiltration. Note
the rock borders
along the
driveway, which
can protect
For existing paved driveways that only
need to be retrofitted with BMPs, no permit is
required, only a BMP site evaluation.
Conveyance and infiltration
In order to meet the requirements of
Chapter 25 of TRPA’s Code of Ordinances,
conveyance structures and infiltration systems,
described in Chapter 4, are often needed on
and next to driveways to capture stormwater
runoff and infiltrate it into the ground.
However, in some cases the existing natural
landscape and vegetation will be sufficient to
infiltrate the required volume of runoff onsite
with no erosive effects on the landscape. If
Conveyance of runoff on
Conveyance structures (i.e. slotted channel
drains, swales) are linear improvements made
on a driveway, installed roughly perpendicular
vegetation and
prevent soil and
nutrients from
moving onto the
paved surface.
to the flow path, which intercept and divert
runoff to an infiltration system or vegetated
area. These structures should usually be
placed at or as near to the property line as
possible to maximize the amount of runoff that
is intercepted and infiltrated. Conveyance
structures should not be placed in public
rights-of-way nor should they direct water into
public rights-of-way.
the site evaluator makes this determination, it
will be clearly written on the evaluation form.
If recommended, drywells, also described
in Chapter 4, should be placed a minimum of
1 foot away from the edge of the driveway.
During installation, you must ensure that
the ground supporting the driveway is not
undermined. Filter fabric is recommended
under interlocking paving stone driveways to
prevent the movement of sand base material
into the drywell. Compaction of soil and
gravel around prefabricated infiltration units is
critically important in drywells placed next to
In many instances where driveways are nearly level, it is
possible to merely slope the pavement to direct runoff to
infiltration systems.
Chapter 3: Paved Driveways ~ 21
The following are brief definitions of commonly
Slotted Channel Drain
prescribed conveyance structures:
1. Slotted drain (Also called trench drains or
channel drains)
A grated conveyance structure, installed at
or below the surface of the driveway, that
transports water underground to an infiltration
system or vegetation. This is the most effective
conveyance structure, but is often the most
One foot
costly. Properly installed slotted drains do not
interfere with snow removal from the surface
of the driveway. There are several different
View of a driveway with a slotted drain that
types of slotted drains that can be installed.
diverts flow to a drywell for storage.
Be sure to choose a brand with removable
grates that can be taken off to clean out
accumulated debris as needed. Some models
include a trap to capture sediment before
releasing stormwater to the infiltration system.
See the diagram and pictures of correctly
installed slotted drains on this page.
Steps for installing slotted drains, channel drains, and trench
drains to convey driveway runoff to an infiltration system:
 Pavement cut
 Channel drain
installed and
cemented in.
 Install optional
 Drywell
properly sized.
 Finished
drywell with
storage medium
inside and gravel
on top.
22 ~ Chapter 3: Paved Driveways
Driveway swales
are valleys in
the pavement
that collect
runoff and
convey it to
an infiltration
system adjacent
to the driveway.
View of a slotted drain (channel drain)
installed to convey driveway runoff to a
drywell. The drain has a removable grate for
ease of cleaning.
2. Swale:
A linear depression in the pavement that
transports water to an infiltration system or
vegetation. In order to properly install a
swale on an existing driveway, a portion of
the driveway must be cut and removed. The
repaired pavement is shaped in a concave
form. On slopes greater than 5%, swales may
not be effective unless installed with a built
up section on the downhill side of the swale.
(Removal of a larger section of pavement
At left, view of
is required.) Swales installed angling down
a driveway with
toward the infiltration system will have a
steeper flowline and will carry water more
a swale that
diverts flow to
efficiently than swales installed perpendicular
a drywell for
to the driveway. Good swale design should
consider the potential damage from snow
plows. All changes in elevation need to be
gentle. See the diagram and photos at right
storage and
infiltration into
One foot
the soil.
of correctly installed swales.
Chapter 3: Paved Driveways ~ 23
A note on berms as conveyance
structures on driveways
In the past, berms were recommended on
the infiltration system required if vegetation
and site characteristics don’t allow for
adequate natural infiltration. See Chapter 4,
driveways being retro-fitted. (The term “berm”
Runoff and Infiltration, for more information on
refers to a linear mound of asphalt placed
infiltration and types of infiltration systems.
on a driveway like a speed bump.) Due to
Please be aware that an infiltration
field observations and homeowner testimony,
system is required at the downslope end of
berms are no longer an acceptable method
the conveyance structure where adequate
of conveying driveway runoff to an infiltration
storage volume or vegetation is not present
system. Berms that are installed on driveways
to infiltrate the required volume of runoff. The
are sometimes constructed from cold asphalt
site evaluator will determine what type of
concrete patch mix. Even when constructed
infiltration system will be required to store and
from asphalt concrete hot mix, Lake Tahoe’s
infiltrate the flow captured by the conveyance
harsh winter climate, with continual freeze-
structure. Generally, several options are
thaw conditions and frequent snow removal
available for infiltration structures depending
View of a berm
operations, berms have been proven to
on the cost constraints of the homeowner.
on a driveway.
lose functionality over time. Most damage
The size of the infiltration system required
Berms are
is caused by snow removal equipment and
to infiltrate the volume of runoff from the
no longer
poor bonding between the berm and the
impervious surface of the driveway will vary
driveway surface. Slotted drains and swales
depending on soil characteristics and the %
have been observed to function effectively at
void space of the material placed inside the
conveying surface runoff for the long term.
infiltration system. Look for the volume of runoff
acceptable as
that needs to be infiltrated written on the BMP
Site Evaluation.
There are some important things to keep in
mind when installing an infiltration system. First,
the infiltration system should be placed in the
flattest area that is available. This will maximize
the storage capacity and effectiveness of the
infiltration system. Secondly, the infiltration
system should be placed slightly downhill of
where the flow exits the conveyance structure.
Water does not flow uphill, so if the infiltration
system is placed uphill of the exiting point
of the conveyance structure the storage
capacity of the infiltration system will not be
Infiltration is the entry or absorption of water
maximized. Third, it is most important that the
(from precipitation, irrigation, or snowmelt)
bottom of the infiltration gallery is excavated
into the soil. An infiltration system provides
level. Terracing techniques can be used to fit
an area for water storage when the rate of
steeper sites. The formulas used to determine
rainfall exceeds the rate of natural infiltration.
the infiltration system storage area assume
It stores runoff so that it has time to sink down
the bottom is level. So if the system is not level,
into the earth. The site’s soil type, the volume
the capacity of the infiltration system will not
of runoff generated from the site’s impervious
meet the requirements to treat the design
surfaces, and the amount of open space in
storm. Infiltration systems are covered more
the water storage area determine the size of
thoroughly in Chapter 4.
24 ~ Chapter 3: Paved Driveways
Planning process for paving an
unpaved driveway
A paving contractor has a lot of control over
where the flow is directed when a driveway
is paved, especially when the property is
relatively flat. It is during the paving planning
process that the flow path of the runoff is
determined. By grading the surface prior to
paving it, the flow can be directed toward
vegetation, off one or both sides of the
driveway, or to an infiltration system. It should
not be directed out toward the public rightof-way. Inspectors will use a hose test to make
sure water does not leave the property.
Keep the following in mind before paving a
dirt driveway:
▄ If adequate vegetation on a level area exists onsite to infiltrate the required volume
of runoff, the driveway should be graded
– sloped so that flow is directed to that
vegetated area if possible.
▄ When natural vegetated areas will be
utilized to infiltrate driveway runoff, the
driveway should be graded such that flow
is dispersed as much as possible, thereby
minimizing the concentrated energy of
the flow and maximizing the contact area
between the vegetation and runoff.
▄ To minimize excavation, infiltration
systems are not recommended where an
adequate amount of vegetation exists to
infiltrate the required volume of runoff. The
exception to this is where there are very
large volumes of runoff, and the infiltration
system is needed to supplement the
existing vegetation to infiltrate the large
volume of runoff. Please contact TRPA or
one of the Conservation Districts to make
the determination if an infiltration system
will be required to infiltrate the volume of
runoff generated from the driveway.
▄ If the driveway must be graded such that
runoff will enter the public right-of-way, a
conveyance structure must be installed
as close to the property line as possible
to intercept the flow and divert it to an
View of a
appropriately sized infiltration system for
driveway with
infiltration onsite.
▄ In some cases, more than one conveyance structure and infiltration system may
paving stones
and a slotted
be necessary to intercept and infiltrate the
runoff flowing from the driveway, particularly when the driveway is very long and/or
Driveway paving options
The use of paving stones is certainly
encouraged to facilitate the infiltration
of driveway runoff. In addition to being
aesthetically pleasing, paving stones allow
a percentage of runoff to infiltrate into the
ground depending on how widely spaced the
paving stones are laid, the steepness of the
driveway, and the amount of soil compaction
A variety
of pervious
surfaces can
be seen at
the South
Lake Tahoe
Garden at
Lake Tahoe
College and
the North
Lake Tahoe
Garden at
Sierra Nevada
Chapter 3: Paved Driveways ~ 25
that has occurred. Unfortunately, paving
be taken when plowing the driveway. When
stones only allow for a small percentage of
installing any type of permeable paving
infiltration. Thus, in most cases a conveyance
surface, a reservoir (permeable subgrade) of
structure and an infiltration system will still
crushed stone must be used under the surface
be required on a paving stone driveway.
to effectively infiltrate runoff. A traditional
Paving stones are considered hard coverage
subgrade of roadbase and sand does not
equivalent to asphalt.
adequately infiltrate runoff.
An important thing to keep in mind when
Property owners who wish to install
paving stones are used to pave a driveway
permeable products on their driveways
is snow removal. While it is possible to
should contact TRPA to determine whether
remove snow from a paving stone driveway,
the products used and the areas involved
care must be taken so the driveway is not
are appropriate for these types of driveway
damaged. Additionally, paving stones are
surfaces. Landowners and contractors should
often not allowed in the public right-of-way,
know that permeable paving products will be
so be sure to check with the appropriate
counted as land coverage.
agency before installation. These driveways
will last longer if the edge is stabilized with
Permeable paving products
Unusual circumstances —
“problem driveways”
Sometimes, particularly when retrofitting
existing paved driveways, obstacles can
The use of permeable paving products
get in the way that make it difficult to install
as alternatives to traditional surfaces like
conveyance structures and infiltration systems.
asphalt is encouraged because of their
These obstacles might include:
ability to infiltrate runoff. Permeable paving
surfaces appropriate for driveways include
permeable paving blocks, permeable
concrete, and permeable asphalt. Snow
removal is important to keep in mind when
these products or other permeable products
are used to pave a driveway. Care should
High ground water
Steep slopes
Limited available area
Retaining walls
Underground utilities
At left, the pervious pavement is laid on top of
a permeable subgrade of gravel. The driveway
below has a steep slope and very little space
at the foot of the slope for an infiltration system.
26 ~ Chapter 3: Paved Driveways
Here are some options you may have when
Two options that may require the design of a
faced with these difficult driveway situations:
qualified licensed engineer include:
1. Break up the flow. Install more than one
1. Installation of a subpavement infiltration
conveyance structure, and utilize surrounding
system. If there is no room to infiltrate the
natural infiltration areas that already exist.
driveway runoff, the only option may be to
Opportunities may exist to convey the water
install the infiltration system under the driveway
by means of a pipe or french drain system to
pavement and divert the flow to it for storage.
an appropriate infiltration area.
2. Cut or move the retaining wall. If
2. Reduce the coverage of the driveway. If
retaining walls are present on both sides of
some asphalt can be removed, the volume
the driveway, you may have to excavate
of runoff is reduced, which in turn requires
out an area for the required infiltration system
a smaller infiltration system. Also, wherever
and stabilize the slope behind it. You would
pavement is removed, effective infiltration
be moving the retaining wall back and
areas can be created.
excavating part of the slope to make room
3. Re-slope the driveway. In some cases
for the infiltration system. If the wall is made
the driveway may be re-sloped so that
of wood, you may be able to cut the wall so
the driveway flow is diverted to vegetated
that the conveyance structure can divert the
areas or areas where infiltration systems can
flow through it to the infiltration system without
effectively be installed.
jeopardizing the integrity of the wall.
4. Work with an adjacent landowner or
contact the county and ask for rights to
Economies of scale
place an infiltration system in the right of way
What types of cost savings could there be for
(encroachment area). On occasion, adjacent
homeowners if the paving contractor could
landowners may have areas where the flow
pave dirt driveways or retrofit existing paved
from the driveway in question can be diverted
driveways for whole streets or blocks at a
for infiltration. Obviously, this takes a friendly
time? The Neighborhood Leader Program can
neighbor, some coordination, and sharing of
serve as a catalyst to find out. Contact your
Conservation District for more information.
5. Opportunities may arise in the future that
would allow a homeowner to pay an offsite
water quality mitigation fee to be used for
Always call USA North before you
dig: 1-800-227-2600
water quality projects in the Tahoe basin in
situations where the infiltration of stormwater
onsite is not economically or physically
Chapter 3: Paved Driveways ~ 27
28 ~ Chapter 3: Paved Driveways
Chapter 4
Runoff and Infiltration
Why are infiltration systems
he purpose of infiltration systems
amount and rate of runoff and its erosive force
is to prevent erosion by infiltrating
downstream. Infiltration systems are practices
storm water into the soil. This reduces
that help large volumes of concentrated
concentrated flow so that it does not
runoff soak into the ground, where soils and
overwhelm downstream systems. Increased
urban and residential development has
plant roots can naturally filter out pollutants.
had harmful effects on Lake Tahoe’s water
Impervious areas generate runoff
quality. Increased development results in an
Impervious surfaces prevent water
increase in impervious areas. Impervious areas
absorption, and cause water to concentrate
do not allow water to soak into the ground,
as stormwater runoff. Types of Impervious
but rather cause it to run over the ground,
Surfaces include:
collecting and carrying sediments, nutrients
and traces of other pollutants to Lake Tahoe.
Roofs - Roofs are impervious surfaces that
Infiltration systems are installed to reduce the
convey water to eaves or gutters. Water falling
Basic working definitions
Entry or absorption of water from precipitation, irrigation or runoff into soil.
The portion of rain or irrigation water failing to infiltrate into soil. Surface runoff is the primary cause of soil erosion and nonpoint source water pollution.
Resistant to penetration by water or plant roots. Impervious surfaces create runoff.
Soil Permeability:
Ease with which water transmits through saturated soil, often expressed as a rate; i.e.
inches per hour.
Problem Drainage: Relates to a high water table and the inability of water to be transported through soil.
Chapter 4: Runoff and Infiltration ~ 29
from eaves or gutters without downspouts
naturally vegetated level areas should be
typically causes erosion and runoff.
protected and used for infiltration. The natural
plant-soil complex can usually treat runoff
Driveways - Driveways are impervious surfaces
better than any artificial infiltration system.
that, without the aid of a conveyance and
Also, runoff is stored in the vegetated cover.
infiltration system, often contribute large
Infiltration systems installed upslope of building
volumes of flow to public right-of-ways.
foundations should be designed to prevent
Consult Chapter 3 for a more complete
water damage (see Conveyance subtitle in
discussion of driveways.
this chapter).
By infiltrating stormwater into the soil via
Compacted Soils - Soils that have been
BMPs, we mimic natural conditions of an
walked, driven or parked on regularly are
undisturbed watershed. As the stormwater
usually compacted enough to prevent water
travels through the soil, sediment is filtered
from entering the soil.
out and some nutrients may bind to the soil
Raised decks and stairways - Structures that
or be taken up by roots. This process helps to
purify the water before it reaches Lake Tahoe.
do not have spaces between wood planks
However, polluted water containing high levels
create impervious surfaces where water can
of nutrients or toxic substances like gasoline
run off. If there are spaces between planks,
and oil can contaminate the soil and ground
water falling through them to the soil below
water. Therefore, stormwater runoff containing
may cause erosion.
these toxic substances must be pretreated
Dog Runs - Paved or not, dog runs become
compacted due to concentrated animal
traffic and cannot support vegetation.
Patios and Walkways - Runoff from paved
patios and walkways can often infiltrate into
the adjacent soil if the area is flat and well
vegetated or mulched.
What are infiltration systems?
Infiltration systems are structures or planted
areas that allow concentrated volumes of
runoff from a property’s impervious surfaces
to soak into the ground. Infiltration systems
are often located under roof driplines, under
gutter downspouts, at the end of conveyance
structures on driveways or adjacent to other
impervious surfaces, such as parking areas. All
infiltration systems must be sized appropriately
according to soil type, soil permeability, and
volume of surface runoff. Whenever possible,
Runoff from paved surfaces can carry pollutants to Lake Tahoe.
30 ~ Chapter 4: Runoff and Infiltration
prior to infiltrating it into the soil. Stormwater
collected on residential areas generally does
infiltrate into the soil. Over time, the systems
fill with sediment and fail to work properly.
By periodically removing the collected
sediments, the system can function at full
capacity. It is good to check your BMPs after
each storm, in the spring, and just before
winter. A visual inspection can determine if
the BMPs are functioning properly: run a hose
over the system to determine if the water
infiltrates or if it overflows and runs off quickly.
By installing a sediment trap upstream of
an infiltration system, the life of the infiltration
system is prolonged. The extra cost spent
installing sumps and clean-outs will be
exceeded by the savings of not having to dig
up and clean the entire infiltration system.
All systems that are backfilled with gravel
should be constructed with maintenance in
mind. A simple layer of filter fabric placed
This infiltration system captures, stores, and
near the top of the infiltration trench will catch
infiltrates roof runoff.
fine sediments and prevent them from being
transported to the rest of the infiltration system.
When the system shows signs of clogging, one
not require pretreatment devices and can
only needs to remove and sift the top 3 inches
usually be safely infiltrated into the soil. If you
of gravel to uncover the fabric. Then carefully
are concerned that a property may have
lift, roll and discard the clogged fabric. Next,
contaminated stormwater, contact the
place a new layer of fabric over the trench
Conservation Districts, TRPA, or NRCS for more
and replace the sifted gravel. A cleanout port
can be used as a means to access storage
Maintenance of infiltration systems
facilities for easy maintenance. (See Chapter
7, on Maintenance)
Infiltration systems require maintenance
and routine checking to remain effective.
Accumulated debris on gravel mulch must
be removed periodically. The gravel, rock or
prefabricated structures that fill the infiltration
system must be periodically removed and
cleaned to keep available storage space
open. How often an infiltration system must
be cleaned is dependent upon site-specific
conditions, the frequency and intensity of
storms and how well the system was installed.
Additional information in maintenance of
BMPs is found in Chapter 7.
Infiltration systems trap fine sediments and
provide storage space for runoff until it can
Common types of infiltration systems:
Underground Infiltration Systems
Above Ground Infiltration Systems
▄ Gravel armoring under driplines on flat or gently
Infiltration trenches (prefabricated or gravel)
Drywells (prefabricated or gravel)
sloping land
Water spreading over flat vegetated or mulched areas
Grassed or rock-lined swales
Infiltration Basins, vegetated or rock-lined
Planter boxes
Chapter 4: Runoff and Infiltration ~ 31
Common infiltration systems
are described briefly below:
Infiltration trenches are shallow rock, gravel, or
prefabricated structure-filled trenches located
adjacent to impervious surfaces and beneath
roof eaves. Their purpose is to infiltrate runoff
from impervious surfaces and to prevent
erosion. Infiltration trenches are applicable
on many sites, but are not appropriate on
slopes unless installed along the contour.
When on a slope, infiltration trenches not
installed level serve as conveyance structures
and their infiltration storage capacity is
limited. Terracing of the trench bottom and
installation of baffles can allow the trenches
to operate properly. In locations where the
foundation would be negatively impacted
by an infiltration trench, a subsurface drain
should be placed under the dripline to
convey the water away from the structure.
Trenches filled with gravel should be bordered
with larger rocks or treated lumber to keep it
clean and in place.
Drywells are rock, gravel or prefabricated
structure-filled pits. Their purpose is to infiltrate
runoff from impervious surfaces preventing
direct discharge to surface waters. Drywells
are applicable to sites requiring additional
storage capacity for runoff from impervious
surfaces, such as at the end of a conveyance
structure on a driveway, or as an alternative
to infiltration trenches on slopes. A gravel
armored dripline can convey the water down
a slope to a drywell at the bottom. They are
also applicable at the foot of downspouts. If
gravel is used to fill drywells, it should be ¾”1½” in diameter.
Gravel Mulch, also called inorganic
mulch, can be used to armor soils in the Lake
Tahoe Basin which have rapid permeability.
Soils of this type have the capacity to
infiltrate the volume of runoff generated by a
typical (19 foot wide) residential roof during
32 ~ Chapter 4: Runoff and Infiltration
a 20 year/1 hour storm which generates
approximately one inch of rainfall. A gravel
mulch layer 3” deep and 18” to 24” wide on
level land under roof driplines is sufficient to
prevent splash erosion and allow runoff to
infiltrate without the requirement of additional
infiltration systems. The gravel used to armor
roof driplines should be ¾”-1½” in diameter.
For soils with slow or moderate permeability,
adequately sized infiltration trenches or
conveyance to drywells are required under
roof driplines. For defensible space purposes,
the gravel mulch should extend under the
roof eaves all the way to the foundation
wall. In areas of high fire hazard, fire districts
recommend inorganic (gravel) mulch five feet
out from the foundation wall. Gravel should be
contained by a border.
Water spreading over large flat vegetated
or mulched areas is an another alternative
that has advantages for cost, aesthetics, and
simplicity. This type of infiltration system should
be used when soils are not compacted and
have good infiltration capacity. If runoff flows
to a flat or gently-sloping, well-vegetated or
mulched area with little runoff potential, it will
infiltrate naturally. Calculation of the amount
of vegetated surface area needed to infiltrate
stormwater is currently being researched.
Water spreading capacity to infiltrate
runoff varies depending on the soil type.
Conveyance structures are often necessary
to redirect water away from foundations to
flat or gently-sloping, well-vegetated areas.
Borders may be necessary to prevent water
from running off the property (e.g. rock,
wood borders or vegetated berms). A major
advantage to using natural infiltration is that
there is no excavation or soil disturbance. A flat
lawn can sometimes function for this purpose.
Infiltration basins are shallow depressions in
the ground or areas bordered by berms which
are designed to store and infiltrate runoff into
the ground. This practice is believed to have a
Grassed swales. The term swale (a.k.a.
grassed channel, dry swale, grassed swale,
biofilter, dry creek bed) refers to an open
channel designed specifically to convey,
treat and attenuate storm water runoff for a
specified water quality volume. As storm water
runoff flows through a channel or series of
channels, it is treated through filtering by the
vegetation in the channel, filtering through
a subsoil matrix, and infiltrating into the
underlying soils. Variations of swales include
the grassed swale and rock-lined swale, which
can be designed to resemble a dry creekbed
with small dams to slow and pool the water.
The specific design features and methods
of treatment differ in each of these designs,
but all are improvements on the traditional
drainage ditch. These designs incorporate
modified geometry and other features for use
of the swale as an infiltration and conveyance
practice. Ponds, basins, and swales can all be
Above Top: This large infiltration basin treats
shaped to meet the aesthetic desires of the
runoff from a multi-family property. Above
bottom: Grassed swales can be used along
roadsides and parking lots to collect and treat
storm water runoff.
Planter Boxes may be designed to make
use of our rare summer rainstorm runoff as
irrigation water. They work best on rapid
high pollutant removal efficiency and can also
help recharge the ground water, thus restoring
low flows to stream systems. Like all infiltration
systems, they need to be sized for the storage
of runoff from a storm of one inch of rain in an
hour, based on the permeability of the soil on
the site. Shallow basins or bermed areas can
also be used as snow storage areas. If used
for this purpose, they should be designed with
permeability soil. Calculation of storage
capacity and treatment capacity of planter
boxes is being researched. The planter box
itself has capacity to hold water from the soil
to the top of the lowest border. The planter
box needs to be strong enough to prevent
structural failure and displacement of soil in
a high flow event. The planter box must be
designed to prevent standing water at the
additional capacity so that a rain-on-snow
event can be treated. If used to treat runoff
from a parking lot where salt is used as a
deicer, the area should be planted with salttolerant, nonwoody plant species or covered
with rock. Shallow basins can also be perched
on gradual slopes like water terraces.
Planter boxes
work best
on rapid
Chapter 4: Runoff and Infiltration ~ 33
foundation. If the planter box is raised, filter
contacting your local Conservation District,
fabric can prevent the fines in the soil from
the Natural Resources Conservation Service
escaping through gaps in the planter box. Be
aware that building codes require a minimum
Tahoe Soil Permeability Rates:
separation of 8” from the soil to the wood
Each BMP site evaluation form shows soil
siding. Defensible space practices also require
information just below the site diagram.
low flammability vegetation and inorganic
The permeability rate measures the
mulch within 5 feet of foundations. Vegetation
maximum speed at which a soil will absorb
in planter boxes should be dense and robust
water in inches per hour. Any water falling
enough to stabilize soil by dissipating the
in excess of the permeability rate becomes
energy from roof runoff. The designer can
stormwater runoff, which flows over the soil
use drywells to supplement the planter box
surface, collecting sediment. Soil drainage
to meet the storage capacity required. They
problems can occur regardless of soil
should not be placed where roof avalanches
permeability if the groundwater table is
can destroy them.
close to the soil’s surface or a compacted
Use your soil characteristics to
design your infiltration system
layer that water cannot penetrate (such as
bedrock or clay) lies below the soil. If the
drainage problem box is checked on a BMP
Infiltration systems will vary from property
Site Evaluation (see excerpt below), one of
to property due to the variation in soil
these circumstances may apply. One of the
characteristics in the Tahoe Basin. The sixty-
Conservation Districts, TRPA, NRCS, or a private
six different soil types in the Tahoe Basin vary
engineer should be consulted before installing
greatly in nutrient content, permeability and
an infiltration system.
drainage properties. All BMP Site Evaluation
reports will have the soil type listed on them,
Calculating volumes of runoff
as shown below. Soil Map Units and their
Runoff calculations will be completed on a
respective permeability rates can also be
BMP Site Evaluation (see diagram next page).
found in Chart 1 of Appendix C. If you do
Calculations are made for a 20 year/1 hour
not have a site evaluation report, you can
storm event, which roughly equals one inch of
determine the soil type on your property by
rain falling in a one hour time period.
Runoff calculations will be completed on a BMP Site Evaluation. See sample below.
Soil Survey Map Unit: JaC
Soil Permeability: 1”/HR
Drainage Problem: N
SEZ or Shorezone: N
Slope: 4%
Vegetate or mulch all bare soil areas
Pave driveway per local jurisdiction requirements
Install swale or slotted channel drain in driveway
~23 ft
Install prefabricated drywell and connect to swale
Prefab Drywell: 80”L x 40” W
6.0 units
or slotted channel drain in driveway
x 12” D
0.4 cu yds
Prefab Drywell: 80” L x 80” W
8.0 units
x 8” D
0.8 cu yds
Prefab Drywell: 29.7’ L x 20” W
9.0 units
x 8” D
1.0 cu yds
25.0 cu ft
31.3 cu ft
Install prefabricated drywell under gutter outlet
75.0 cu ft
Install prefabricated drywell along dripline
34 ~ Chapter 4: Runoff and Infiltration
Runoff Calculations
The volume of runoff produced by the design
storm is calculated on the site evaluation
Original formula for calculating
infiltration system storage capacity
report. To compute it yourself, use the formula
below, or use the spreadsheet developed by
NRCS. Call (530) 543-1501, ext.104.
(This calculation is already completed
on the site evaluation report.)
Note: Distances are measured horizontally. The
coverage that produces runoff is a flat plane
projection or a plan view (roof area ft²).
X length' X
X length' X
% void X
(roof area ft²) x 1/12 foot of rain = volume of
runoff ft³
(25ft x 15ft) x 1/12 foot = 31.25 ft³ of runoff
X length' X
for half of the roof
25 feet
The three levels of the above formula are
based on the three parts of the trench or
gallery to infiltrate stormwater.
15 ft
▄ Entire bottom of trench takes on
water at the full rate of permeability.
Static pressure created by the water
stored in the trench is exerted on the
bottom soil.
▄ Sides of the trench only get credit
for infiltrating 1/6th of the wetted
wall of the trench.
▄ Void space created in the drywell is
credited for storage volume.
Different materials can fill
subsurface infiltration systems
Infiltration trenches and drywells can be filled
with different types of materials. The most
commonly used materials to fill infiltration
systems are gravel or prefabricated infiltration
units. Prefabricated infiltration units are made
of materials that provide a rigid structure
with a large void space available to store
water. This space within the infiltration system
is called void area, which allows water to be
stored beneath the ground surface until it
completely infiltrates into the surrounding soil.
Chapter 4: Runoff and Infiltration ~ 35
Different materials have different amounts
materials, which have up to 95% void space.
of void areas, referred to as percent void.
Another drawback to rock infiltration systems
¾ to 1 ½ inch graded gravel, for instance,
is maintenance. Rock infiltration systems
has roughly 33 percent void space, while
become “silted in” over time if there is
some prefabricated structures have up to
sediment entering the system. As the sediment
95 percent void. The percentage of void
settles out of the runoff in the system, it clogs
space is based on the volume of open
the void spaces, which renders the system
storage space that exists in the infiltration
ineffective. Once silted in, the rock infiltration
system in proportion to the total volume of the
system must be completely dug up, the gravel
completed infiltration system.
must be cleaned and replaced, and the
sediment disposed of properly. To increase
Two commonly used infiltration system
maintenance intervals and avoid having to
materials are contrasted below.
dig up the entire system, rock filled systems can
be wrapped with a filter fabric on the sides
Rock infiltration systems have been used
and top and then covered with a 3” layer
for many years in the Tahoe Basin. They
of rock. This way, when the fabric becomes
are a tested method for infiltrating excess
plugged with sediment, the owner only has to
water. While effective, their drawbacks are
remove the top 3” layer of rock, cut out the
numerous. As stated above, rock typically
top layer of fabric, place a new layer of fabric,
has only has 33 percent void space, so in
and finally place 3” of clean rock back on top
order to infiltrate a required volume of runoff,
of the system.
the excavation for an infiltration system
filled with rock must be almost 3 times larger
Prefabricated infiltration systems consist
than one filled with prefabricated infiltration
of proprietary BMP product materials that
Below: View of rock filled infiltration system.
At right: View of a prefabricated infiltration
product about to be wrapped in filter fabric
and placed in an excavated hole below a
conveyance structure.
36 ~ Chapter 4: Runoff and Infiltration
have a large percent void space that
are wrapped in a geotextile fabric and
Prefabricated filled Drywells vs. Gravel/Rock filled Drywells
placed in an excavated hole in the ground.
Prefabricated infiltration systems function
▄ More void space—up to 95%.
▄ Less void space—around 33%.
almost identically to rock infiltration systems,
▄ Requires smaller excavation.
▄ Requires larger excavation.
but due to the increased void space, they
▄ Possibly less labor costs.
▄ Possibly more labor costs.
▄ Easier to maintain.
▄ Difficult maintenance.
▄ Clean top 3” of gravel every 2-5
▄ Clean top 3” of gravel every 2-5
require less excavation and therefore less
labor. Another advantage to these systems
is maintenance. Prefabricated infiltration
systems are often covered with approximately
years depending on contamination.
years depending on contamination.
▄ If maintenance is deferred too long,
three inches of gravel. If they become silted
all gravel may have to be removed
and cleaned.
in, only the top three inches of gravel must
be cleaned to keep the system functioning
▄ Cost of material.
▄ Cost of material.
properly. Although silting in may occur slightly
▄ Expensive compared to rock.
▄ Inexpensive compared to prefab.
more often than with rock infiltration systems,
▄ Overall cost may be less due to labor
▄ Overall cost may be more due to
three inches of gravel is easier to clean
than an entire trench or drywell. Installing
prefabricated infiltration structures is slightly
and maintenance.
labor and maintenance.
▄ New skill to learn, but fairly simple
▄ As simple as digging a hole and
filling it with rock. Labor involved to
wheelbarrow the gravel.
more complex than installing rock filled
infiltration structures, but with a little practice it
will become routine.
There are several proprietary BMP products
▄ Stricter dimensions for hole size, but
may be variable as long as overall
▄ Hole size may be variable as long as
overall volume is the same.
volume is the same.
designed for use as prefabricated infiltration
systems. Void space is variable between
different prefabricated materials. “Rainstore”
(manufactured by Invisible Structures),
“High Capacity Infiltrator Chambers”
(manufactured by Infiltrator Systems), “Storm
Tech Chambers” (manufactured by Storm
Tech) and “Raintank” (manufactured by
Atlantis Water Management) are currently
the most common prefabricated infiltration
materials used in the Tahoe Basin. These
products vary from 80% to 95% void space. This
allows prefabricated infiltration systems to be
significantly smaller, with less excavation than
traditional rock infiltration systems. Information
on specific proprietary BMP products is for
informational purposes only. University of
Nevada Cooperative Extension and its partner
agencies do not endorse any stormwater
All infiltration systems must be sized
appropriately according to soil type, soil
permeability, and volume of surface runoff.
Old fashioned “Standard sized” drywells and
infiltration trenches may not be large enough
to store runoff in a 20 year, 1 hour storm.
Components of an effective infiltration system:
 Install a sump pretreatment area or “catch
basin” to capture sediment for “clean-out”
before it enters the infiltration system.
 Wrap the system with filter fabric to avoid
migration of fine material into void spaces
of infiltration system.
 Include borders to define the edges of
surface infiltration systems. This helps to
contain the system for neat housekeeping.
 Disperse energy at the discharge ends of
drainage pipes or conveyance structures.
 Spread flows at the discharge end of a
system on a level, vegetated surface
to prevent concentration of flows and
 Build in access ports and clean outs that
aid in the maintenance and periodic
monitoring of the system.
Chapter 4: Runoff and Infiltration ~ 37
Here are some important things to keep in
 A geo-grid (such as Tenax or equivalent)
mind when installing infiltration systems:
is necessary to protect the top of some
types of prefabricated structures and
 Determine appropriate dimensions based
zip-ties must be used to anchor it to the
on a completed BMP Site Evaluation.
 If disturbing more than 3 yards of soil
out of grading season, contact TRPA for
prefabricated system.
 A geotextile fabric must be draped around
the top and sides of all prefabricated
permitting requirements. Install proper
storage structures with 3” of overlapping
temporary BMPs to protect disturbed soil.
 Infiltration systems must not adversely
affect nearby foundations or footings.
fabric at all seams.
 Backfill around prefabricated structures
with the excavated material.
Use an impermeable layer of plastic
to prevent the migration of water into
the crawl space. Care must be taken
prefabricated structures with a
minimum of 3” gravel.
to properly assess soil and groundwater
conditions to ensure that water does not
degrade the integrity of the foundation or
12 A drainage inlet device to allow inflow of
water into the prefabricated structure may
cause mold growth. See next section to
be necessary. Grating is recommended
learn how to convey runoff to infiltration
for ease of maintenance.
systems that are not located above the
 Gravel mulch under driplines should be
at least 18 inches wide and at least 3
inches deep. When the dripline is 32 feet
or higher (2 story structure) above the
mulch, the armoring layer should be at
Common methods of
conveyance to aid infiltration
Conveyance methods are often needed
to transport runoff to appropriate areas for
infiltration. Common conveyance treatments
least 24 inches wide for increased splash
▄ Subsurface conveyance of water away
protection. Bordering structures should be
from up-slope portions of foundations
▄ Gutters, downspouts or deflectors
▄ Slotted drains or swales (asphalt, concrete,
used to isolate and contain gravel armor.
 When excavating for prefabricated
structures leave an extra 2” + on all
vegetated, and/or rock lined)
▄ Gravel trenches or gravel armor
sides. Allow for 4” - 6” extra depth. It
is recommended that 3” of gravel be
Subsurface drains capture runoff and
laid to even and level the base of the
convey water to treatment areas or away
excavated area.
from sensitive structures vulnerable to water
damage such as foundations. (Infiltration
Always call 1-800-227-2600 before you dig.
systems should not be installed upslope of
foundations). Subsurface drains rarely infiltrate
 Storage and infiltration structures must be
installed level and along the contour of
the existing slope.
a significant amount of water.
There are local site conditions, such as slow
soil permeability, steep slopes, and localities
near sensitive structures where the standard
38 ~ Chapter 4: Runoff and Infiltration
design may need to be augmented by
the addition of a subsurface drain to more
At left,
efficiently convey water to an infiltration
Schematic view
system. This standard applies to the design
of a typical
and installation of perforated pipe conduits
placed beneath the surface of the ground, to
provide for the collection and conveyance of
Below, View of
snowmelt and storm runoff from roofs.
a cleanout and
sediment trap.
Subsurface drains should be used
for applications in the Lake Tahoe Basin
covering less than 3000 square feet of
contributing roof surface area. A subsurface
drain can be installed using standard 4-inch
diameter perforated PVC pipe or perforated
polyethylene tubing. Trenches should be
excavated to create a minimum 1% slope
in the direction of flow. In addition, an 8
mil heavy gauge plastic liner should be
placed at the base of the trench to capture
the runoff and direct it into the drainpipe.
Geotextile fabrics may replace plastic liners
for applications where water will not flow or
percolate towards a foundation. Refer to the
diagram for a typical installation design.
Cleanouts and/or sediment traps should
be installed at the upper and lower end of
each pipe section, and at all bends and
abrupt changes in slope. Cleanouts can be
constructed by the inclusion of an elbow or a
‘T’ extending above the surface and capped
with a threaded or slip cover. Inline sediment
traps can be included into the system by
placing a pre-cut culvert section vertically into
the trench. Refer to the figure on this page for
All materials should comply with the following applicable
reference standards:
▄ ASTM D2729 - Polyvinyl Chloride (PVC) Sewer Pipe and
Fittings or ADS
▄ ASTM F405 - Corrugated Polyethylene Tubing and Fittings
▄ HDPE Pipe specifications
▄ Gravel for dripline drains should be clean, washed, free
of fines and poorly graded 3/4 to 1-1/2 inch diameter.
installation details.
Subsurface drainage systems deliver flow
contact with protruding or sharp rocks. The
to a drywell, where runoff is allowed to infiltrate
trench for the standard 4” subsurface drain is
into the surrounding soil. Drywells require the
to be lined with a heavy gauge plastic liner
design expertise of a qualified professional to
prior to placement of pipe. Non-perforated
insure adequate capacity and performance.
pipe or tubing may be used when the line
The trench should be excavated to the
passes through areas where root growth may
dimensions indicated in the diagram on the
create an obstruction, or when crossing hard
previous page. The trench bottom should be
rocky areas.
smooth and free of clods, loose or exposed
Subsurface drains require maintenance
rock. Care should be taken when placing the
to continue to be effective. Buildup of leaves,
pipe into the trench bottom to avoid direct
conifer needles and sediment should be
Chapter 4: Runoff and Infiltration ~ 39
periodically removed from the drain and
or infiltration systems. Downspouts are highly
clean-out access pipes to ensure adequate
recommended to prevent splash from gutters,
capacity. Further maintenance should
but usually require the addition of an infiltration
be performed on all sediment traps and
system below them to infiltrate the conveyed
infiltration drywells to remove the buildup of
water. Open gutters and deflectors must have
sediments from the bottom of the structure.
soil protection and an appropriate infiltration
Vactor clean-outs are best when feasible.
system installed where the runoff hits the
All installers and homeowners should
note that the design of this shallow drainage
system does not include the ability to support
Vegetated or Rock-lined Swales are
extreme surface loading due to vehicular
conveyance structures that are often used
traffic. Damage to the pipe and reduced
beneath roof driplines. A vegetated or rock-
long-term function may result from driving
lined swale is designed, shaped, and lined with
vehicles over the top of the trenches.
vegetation or rock to convey and infiltrate
surface runoff. Healthy, well-maintained
Roof runoff conveyance (gutters, downspouts
vegetated swales have better soil protection
or deflectors)
and increased infiltration potential compared
Water falling on impervious surfaces, such
to rock-lined swales.
as the roof of a house, collects at the downslope edge. Most homes in Tahoe do not
Gravel Armor is generally three inches of
have gutters, so water is conveyed to the
gravel mulch and is used to eliminate splash
roof eave. The surface below the roof eave
erosion and protect soil beneath roof driplines.
that receives the concentrated water flow
If slopes are modest, and soil is of high
is the dripline. Several options are available
permeability, water will infiltrate as well (consult
to convey the concentrated water to an
the Infiltration section of this chapter).
appropriate infiltration system. Allowing the
water to fall from a dripline is acceptable if
Gravel Trenches are often improperly installed
an appropriate infiltration system is installed
as infiltration systems. When installed down
along the dripline area (See “Common
a steep slope, gravel trenches serve as
Infiltration Systems” p. 32). Another option
conveyance structures and their storage and
is to capture the water in gutters, which
infiltration capacities are limited. Consult the
creates higher concentrations of water that
infiltration section of this chapter for further
require additional conveyance measures
Any infiltration system such as
this gravel trench will fail to work
properly if its bottom is not level
or if the stored runoff can escape
out the lower end
40 ~ Chapter 4: Runoff and Infiltration
Chapter 5
Slope Stabilization
n many cases a BMP Site Evaluation will
successfully establishing vegetation.
call for slope stabilization. While soil loss
Note: Some of these practices are very
can occur on level ground during high
technical in nature and may need a qualified,
wind or rainstorms, soil erosion is much
licensed engineer’s assistance in design and
more severe on unvegetated, sloping ground.
The following information will help you
It is important to note in this illustration that
determine what methods can be used to
slope stabilization with vegetation and mulch
successfully stabilize everything from a slight
is generally successful only on slopes up to
slope to a steep, severely eroding slope.
50% in steepness. Anything greater than 50%
One method alone is not as effective as a
should incorporate biotechnical methods such
combination of different methods.
as willow wattling, or structural methods, such
As the following diagram shows, the
as terraces, concrete or wood retaining walls,
steeper the slope, the greater the difficulty in
erosion control blankets or rock retaining walls.
The steeper the
slope, the more
difficult it is to
revegetate bare
soil and stabilize
the slope.
Chapter 5: Slope Stabilization ~ 41
Below, a rock-faced retaining wall with nearly
level planting terraces above it stabilizes and
beautifies this slope.
Moderate to
steep slopes
can be
stabilized with
an erosion
control blanket,
rip rap, or a
of river rock or
other mulch and
Extremely steep, eroding slopes like the one
Guidelines for stabilizing slopes of
various steepness
Moderate Slopes (< 33% slope): A
above need to be stabilized by incorporating
structural means such as retaining walls or
sturdy terraces.
combination of vegetation and mulch are
effective on moderate slopes. (See Chapter 6:
Vegetation and Mulches for more information
on successful revegetation techniques
on flat areas and slopes). Mulches such
as wood chips, pine needles, or river rock
provide a good protective ground cover until
vegetation becomes established. Temporary
controls such as erosion control blankets can
also help stabilize bare soil while vegetation
gets established.
Steep Slopes (33%-50% slope): On steep
hold the soil in place. The leaves, needles and
slopes, more care is needed in selecting
twigs will reduce the impact of rain and wind,
appropriate plants and the planting
and the added organic matter will improve
technique. If the plants chosen and methods
water infiltration. Again, erosion control
used are appropriate, vegetation can provide
blankets and mats will help in preventing
excellent long-term erosion control. As plants
erosion while the vegetation develops and
develop, the roots will knit together and help
establishes a healthy community.
42 ~ Chapter 5: Slope Stabilization
Other ways
to stabilize
slopes of over
50% include
blocks, wood
retaining walls
and riprap.
Extremely Steep Slopes (> 50% slope):
Combining erosion control practices is more
effective on extremely steep slopes than
applying a single practice. Terraces, wood
retaining walls or rock retaining walls are
usually necessary to stabilize the toe of these
over steepened slopes in combination with
either revegetation and mulching the area
and/or applying biotechnical methods.
The slope above and behind the retaining
structures should be graded to as gentle a
slope as possible to provide for revegetation.
Use of native or adapted vegetation along
the top and around the retaining structures
increases their effectiveness. Retaining walls
over three feet in height must be designed by
an engineer and permitted by TRPA or your
local building department. A BMP Retrofit
permit may be needed for slope stabilization
work that disturbs between 3 and 7 cubic
yards of soil, and is always needed for work
that disturbs more than 7 cubic yards of soil.
Terraces made
with rock
breastwalls, left,
have created
good areas for
Below, bundles
of dormant
willows tied
into a willow
wattle ready
for installation
across a steep
Remember to call 1-800-227-2600 before you
Methods for stabilizing slopes
greater than 50%
(30 degrees or 2:1)
Willow Wattling - This practice, also called
contour wattling, involves staking long bundles
of fresh willow cuttings in shallow trenches that
have been dug along the contour lines of
cut or fill slopes. Once the bundles or wattles
are staked into the slope and covered with
stabilized, packed topsoil, they intercept runoff
Chapter 5: Slope Stabilization ~ 43
from the slope above and help infiltrate it into
Terraces - The steepness of the slope will
the soil. If the site is carefully irrigated for the
dictate the height of the terraces. The terraces
first few growing seasons, the willow branches
should be high enough to allow the soil behind
will sprout and root, providing excellent
them to be graded to an almost level surface.
vegetation cover and wildlife habitat. Other
Terrace walls, like any retaining walls, need to
approved biotechnical BMPs for slopes over
be engineered if over 3 feet in height. Do-it-
50% include brush matting and brush layering.
yourselfers can create a series of terrace steps
See Appendix D for more details on these
using walls less than 3 feet high. Materials used
for building terraces include recycled plastic
This diagram illustrates how methods used to control erosion vary with the steepness of the slope. While plants and
mulch work well on moderate slopes, steeper sites generally require structural strategies as well. See Chapter 6:
Vegetation and Mulch for information on specifics of vegetation.
44 ~ Chapter 5: Slope Stabilization
products, treated wood, rock and interlocking
concrete blocks. Ensure that the terrace
material is strong and anchored well to stay in
place. Large terraces should be tied securely
into the slope and properly drained.
Wood Retaining Walls - Six-inch by six-inch
posts set in concrete two feet below the
ground generally make a sound anchor
for wood retaining walls, but need to be
engineered if the wall is over three feet in
height. Vegetation should be established on
the slope above the wall. Wood retaining walls
are most often located between the base of
a slope and an adjacent road, driveway or
Above, a rock-faced retaining wall adjacent to a driveway.
drainage way. Permanent structures should
not be installed in the right-of-way.
Rock Retaining Wall - Rock retaining walls are
an alternative to wood retaining walls and
are often used next to a roadway or drainage
way. As opposed to rock riprap, which armors
the ground, rock retaining walls support the
slope and are built from rock 10 inches to
2 feet in diameter. A footing trench is dug
along the toe of the slope and the largest
boulders are placed in the trench. Subsequent
rocks are laid with three or more bearing
Erosion control blankets:
▄ Accelerate vegetative development while
decomposing over time and becoming
part of the soil.
▄ Protect disturbed or bare soil from rain and
surface runoff.
▄ Increase infiltration.
▄ Decrease soil compaction and crusting.
▄ Protect seeds from impact and predators.
▄ Moderate soil temperature.
▄ Increase soil moisture retention.
points on previously laid rocks. The external
face of the wall should incline slightly uphill.
Since the slope above the wall will be flatter
than before, it should be easier to establish
Applications: Erosion control blankets are
most effective when used for the following:
▄ Slopes and disturbed soils where mulch
vegetation above the wall. (Note: make the
must be anchored and other methods
slope above the wall as flat as possible—never
such as crimping or tackifying are not
more than 25%.) A concrete retaining wall can
feasible or adequate.
be made to look like a rock retaining wall by
covering it with rock and mortar (see photo
this page).
Erosion control blankets and
Purpose: Erosion control blankets or mats
are biodegradable products that are used
for temporary or permanent stabilization of
▄ Steep slopes, generally steeper than 3:1.
▄ Slopes where erosion hazard is high.
▄ Critical slopes adjacent to sensitive areas
such as streams, wetlands, or other highly
valued resources.
▄ Disturbed soils where plants are slow to
develop protective cover.
▄ Channels intended to be vegetated
where the flow velocity is low.
disturbed soils.
Chapter 5: Slope Stabilization ~ 45
Limitation: Erosion control blankets are not
▄ Lay blankets loosely and maintain direct
suitable for rocky sites or areas where final
contact with the soil – do not stretch. If the
vegetation will be mowed. Proper site
blanket is not in intimate contact with the
preparation is necessary to ensure adequate
soil, water will be able to run down the soil
contact of the blanket/matting with the soil.
beneath the blanket.
▄ Staple blankets sufficiently to ensure that
Installation: Follow manufacturer’s
materials will remain in direct contact with
recommendations for installation. Please
the soil.
compare the instructions below with the
illustration on the next page.
▄ Prepare and smooth soil on slope. Plant
seeds if desired.
▄ Begin at the top of the slope and anchor
Inspection and Maintenance: Erosion control
blankets, if properly installed, require little
maintenance. However, periodic inspections,
especially in the late fall and early spring, and
the blanket in a 6 inch deep by 6 inch
while the vegetation becomes established
wide trench. Backfill trench and tap earth
will keep the erosion control blanket effective.
When inspecting an erosion control blanket,
▄ Unroll blanket down slope in the direction
of water flow, not horizontally.
▄ Overlap the edges of adjacent parallel
rolls 3 inches and staple every 3 feet.
▄ Use wire staples No. 11 gauge or heavier,
or follow the manufacturer’s instructions.
The “U” shaped staples shall be 6” to 10”
long with a 1” crown. Use longer staples in
loose or sandy soils.
▄ When blankets must be spliced, place
blankets end over end (shingle style)
with 6 inches of overlap. Staple though
overlap areas, approximately 12 inches
Note how the
erosion on the
bare slope (left)
has deposited a
fan of sediment
at the bottom.
This will be
prevented on
the slope with
the erosion
control blanket
46 ~ Chapter 5: Slope Stabilization
be sure to note the following:
▄ Vegetate and mulch the blanket
according to design.
▄ Inspect blankets and mats before and
after significant rain events for erosion and
undermining. Repair failures immediately.
▄ If washout or breakages occur, re-install
or re-anchor materials only after repairing
damage to the slope or channel (rills,
gullies, etc.).
Illustration of
Erosion Control Blanket
installing an
erosion control
Backfill and compact dirt in
the 150 mm X 150 mm (6 in. X 6 in.)
trench after inserting staples
through the material.
Insert staples through the blanket in a
150 mm X 150 mm (6 in. X 6 in.) trench
with each pattern of 3 staples being
about 500 mm (20 in.) apart.
blanket on a
hillside (From
for Effective
As an alternative to trenching when
top of slope is relatively flat, extend
material about 1000 mm (40 in.) on
top of the ground and randomly insert
staples through the material about
500 mm (20 in.) apart.
Sediment and
Erosion Control
800 mm
Staples must be
inserted through
overlap material.
on Construction
Maximum staple spacing.
Blanket material must overlap at least
150 mm (6 in.) and staples inserted
through both fabrics at a maximum
spacing of 1000 mm (40 in.) apart.
At end of slope, secure blanket
material by inserting staples
about 500 mm (20 in.) apart
through the fabric.
Blanket material must overlap at least
150 mm (6 in.) and staples inserted
through both fabrics at a maximum
spacing of 500 mm (20 inc.) apart.
Home Landscaping Guide for Lake Tahoe
and Vicinity. 2002. University of Nevada
Cooperative Extension.
TRPA’s Handbook of Best Management
Practices. 1987. Tahoe Regional Planning
Chapter 5: Slope Stabilization ~ 47
48 ~ Chapter 5: Slope Stabilization
Chapter 6
Vegetation and Mulch
very Site Evaluation requires property
community, using natural organic materials
owners to “vegetate or mulch all
is likely to produce the best results with the
bare soil areas.” When water is
least potential for pollution (however, do not
unable to infiltrate into the soil due to
use fresh manure). Compost and slow release
soil compaction or the presence of impervious
organic fertilizers are the most trouble-free
surfaces, it accumulates on the surface,
and dependable type of organic matter that
creating runoff. This runoff erodes bare soil and
can be added to poor soil. If your vegetation
carries it and attached nutrients directly to
is failing, consider calling a Natural Resources
streams and eventually to Lake Tahoe. New
Conservation Service (NRCS) soil scientist who
research indicates that the most cost-effective
can help you test your soil, determine what is
way to protect Lake Tahoe is to keep soil in
lacking and make suggestions for appropriate
place on the landscape by protecting bare
soil amendments.
soil. (See diagram at right.)
Vegetation and mulch can effectively
stabilize soil and infiltrate runoff from
developed areas, reducing erosion and
effectively filtering sediment. Robust
vegetation depends on healthy soil with
adequate nutrients of the appropriate type.
Healthy soil allows roots to penetrate deeply
and water to infiltrate as if it were a sponge.
In order to create a successful
revegetation project, you must first consider
the soil. Plants get their nutrition from the soil,
so if nutrients are lacking, the vegetation
will not flourish. Organic matter provides
most of the nutrition in natural, undisturbed
settings. In trying to develop a good plant
Because bare soil is extremely vulnerable to raindrop impact and
soil loss by wind or water, it is especially important to protect bare
soil areas with vegetation and mulch.
Chapter 6: Vegetation and Mulch ~ 49
TRPA requires that you choose native and
plants which out-compete native species and
adapted plants for Lake Tahoe. Native plants
decrease biological diversity. Some common
were here prior to the arrival of European-
invasive and noxious weeds that pose a threat
American settlers, while adapted plants
to the Tahoe Basin include tall whitetop (also
originated elsewhere, but are also well suited
known as perennial pepperweed), Scotch
to Lake Tahoe’s climate. Once established,
broom, oxeye daisy, Eurasian watermilfoil,
native and adapted plants need little to no
Russian knapweed, spotted knapweed,
fertilization or irrigation unless it is a drought
Canada thistle, bull thistle, yellow starthistle,
year or the plant is not suited for its site. Look
dalmatian toadflax, yellow toadflax, and
for perennials rather than annuals when
diffuse knapweed. For more information on
shopping for native and adapted plants at
invasive and noxious weeds, see Appendix
your local nursery. While annuals provide
F and visit the California Department
pretty color, they should be used sparingly as
of Agriculture’s Weed Encyclopedia at
they provide a short-term solution to a very
large problem — erosion. There are a great
many native plants that are available for
A flat vegetated and mulched area is shown
landscaping that are colorful and require little
care once established.
When choosing plants, be sure to select
species that are considered to have a low fire
hazard (See Tables 1 and 2 in Chapter 7 of
the Home Landscaping Guide for Lake Tahoe
and Vicinity for a list and color photos of TRPA
approved plants). This will help reduce the
chance of fire spreading from the wild land to
your structures.
Be careful not to choose plants
considered invasive or noxious. These are
All completed BMP site evaluations direct
property owners to “vegetate and mulch all
Reasons for creating a vegetated landscape
using native and adapted plants
at Tahoe
bare soil areas.” TRPA will not issue a BMP
certificate of completion for the property
if bare soil is evident. A combination of
vegetation (native and adapted ground
covers, shrubs, trees, grasses) and mulch (pine
 Protects against Erosion
needles, chipped wood, bark mulch, stones or
 Requires Less Water and Fertilizer
gravel) are most effective. Depth of the mulch
 Minimizes Maintenance
should be between 1 ½ to 3 inches, except in
 Adapted to Tahoe climate
the case of pine needle mulch, which should
 Attracts Wildlife
only be 1 to 2 inches deep. See the section
 Improves Aesthetics & Property Value
on mulches below for effective depths and
considerations regarding pine needle mulch
(See Chapter 7 of the Home Landscaping Guide for
Lake Tahoe and Vicinity for a list and color photos of
TRPA approved plants).
and defensible space.
When bare soil exists on slopes, erosion risks
increase, and extra measures are required. If
slopes are over 50% in steepness, mechanical
50 ~ Chapter 6: Vegetation and Mulch
structures like terraces and retaining walls are
required in addition to vegetation and mulch.
(See Chapter 5 for details.)
Steps to a successful revegetation
 Test Soils. First you need to determine
whether your soil has adequate nutrition for
revegetation. Contact a NRCS soil scientist for
 Apply soil amendments. Amendments will
usually consist of compost and a slow-release
organic fertilizer, but depend on the results of
the soil tests. Fresh manure should not be used
as a soil amendment.
 Incorporate soil amendments into soil.
Tilling soil amendments into the soil to a depth
of 6 to 8 inches gets the nutrients to the plant
roots and breaks up any soil compaction that
may exist.
 Select appropriate plant species. This
selection will depend on the goals of the
project but needs to consist of native and
adapted plants appropriate for the site’s
 Apply long-lasting mulch. Pine needles
and wood chips provide long lasting mulch
in many cases. Plants usually take 2 to 5
years to provide enough organic material
to provide their own protective mulch. The
mulch that you apply should last until plants
are producing their own. Wood chips aren’t
appropriate for slopes greater than 33%
because they will migrate off the slope.
 Tackify mulch. In some cases and
especially for steeper slopes, mulch needs to
be stabilized with an organic tackifier, which
 Irrigate carefully. Irrigation will allow
seeds to germinate quickly and will help
transplanted seedlings survive. Since the
soil has been adequately amended and
mulched, irrigation should be applied slowly
and carefully, so that the root zone is wetted
without causing any runoff. During the first
season, the soil should be kept moist. If seed
or seedlings dry out, they die. Do not over
water. Gradually wean the plants to less
frequent watering in late summer. By the
second season, watering plants every 2-3
weeks during summer is usually sufficient.
Plants should be well enough established after
two growing seasons to not need irrigation.
Special considerations for
planting beds near structures
A vegetated dripline is the area below the roof
dripline (where water drips from your roof onto
the ground) that contains mature, established
vegetation. A clear example of this (see page
33) is a dripline covered with a thick mat of
grass or other vegetation. If you design a
flowerbed for the dripline, you must address
the following:
Border the planting bed. Use landscape
edging tall enough to retain all of the soil in
the event of an extreme precipitation event.
Place filter fabric along the inside edge of the
border to retain fine sediment.
Protect the foundation from mold. The planting
bed should be at least 4 feet wide and
graded so that water drains away from the
structure. An impermeable membrane can
be installed along the foundation as well. Use
only drip irrigation to minimize the amount
of water applied to the planting bed and
to ensure that the foundation is not being
is a glue that holds mulch in place until plants
are established.
Chapter 6: Vegetation and Mulch ~ 51
Employ mulching techniques that minimize
fire hazards. Although the vegetation will help
Soil amendments vs. mulch
Soil Amendment
infiltrate water and reduce raindrop impact
Organic material added to the soil will
during a storm event, bare soil is still vulnerable
promote healthy soil and plants. Add compost
to wind erosion, and requires mulch to help it
to the top 4 to 6 inches and mix it in with
stay in place. For the first five feet out from the
your native or disturbed soil. Do not use fresh
foundation, apply a layer of inorganic mulch
manure. An organic soil amendment will help
such as gravel or rocks to reduce fire hazard.
keep moisture in the soil for a longer period
Outside the first five feet, you can install 1-2”
of time, increase infiltration and provide
of pine needle mulch or 2-4 inches of wood or
essential nutrients to your vegetation resulting
bark mulch such as fir, redwood or cedar.
in increased plant growth. Soil amendments
Employ planting techniques that minimize fire
hazards. Use only herbaceous (not woody)
are more effective than fertilizers because they
help to create a healthy soil for the long term,
while fertilizers only provide instant food for the
plant species with an airy stem spread such as
plants and tend to wash through the soil profile
columbine and bleeding heart. Total canopy
quickly, polluting groundwater.
cover at maturity should not exceed 50%.
Aerate/Till Soil
If you choose to install planting beds to
Many soils become compacted when
prevent erosion under driplines, a fire
repeatedly walked or driven over. Compacted
hazard may be presented. Vegetation and
soils no longer infiltrate water and contribute
wood mulches close to structures have the
runoff that carries nutrient-laden soil particles
potential to carry wildfire to the building.
to Lake Tahoe. Compacted soil makes it
Do not use high fire hazard plants. Drip
difficult to establish healthy vegetation
systems are recommended to maintain
because the roots are not able to penetrate
adequate moisture levels close to structures.
the soil. Before revegetating compacted
It is also important to remove dead or dying
areas, be sure to till soil amendments into the
vegetation during the growing season. For
soil to a depth of 6 to 8 inches. It is helpful to
example, native grass and other perennials
start with a rototiller for severely compacted
should be mowed once they dry out. These
sites. A shovel will also do a good job, but will
measures will not eliminate the fire hazards but
take extra effort to get to the depth needed
will help to minimize them.
for a healthy root system.
Vegetated infiltration swales and basins.
Mulch covers the soil surface
Vegetation and mulch are very useful and
The term “mulch” is used to describe a loose
attractive when employed in above-ground
ground cover that protects the soil surface
infiltration systems (Chapter 4, pp 32-33).
from wind and water erosion. Mulch also
Property owners can make shallow, bermed
prevents moisture loss from the soil, reduces
basins for storage and infiltration of snow and
weed growth, adds nutrients to the soil,
snowmelt. If planted with hardy perennials
and helps insulate the soil from extreme
and mulched, these become attractive
temperature changes. Inorganic mulches such
“rain gardens” in summertime. Careful
as gravel do not provide as many benefits as
consideration of appropriate vegetation
organic mulches, but can be beneficial when
is crucial to create a low maintenance,
used appropriately and work well to reduce
effective system.
wildfire threats near structures.
52 ~ Chapter 6: Vegetation and Mulch
Organic mulches include pine needles
(below) and bark or wood chips.
Shown above, a combination of organic
mulch (bark) and inorganic mulch (rock).
Mulch Depth
When required on a residential property,
properly installed organic mulch is effective at
reducing erosion potential and fire hazards.
Wood or bark chips should be from 1 ½ to 3
inches deep, and pine needle mulch should
be between 1 and 2 inches deep. Inorganic
mulch (i.e. gravel) should be at least 3 inches
deep in all cases. The deeper the mulch,
the more effective it will be at keeping out
weeds, holding in and absorbing moisture,
and protecting the soil against heavy rain or
to help protect your plants. If you use pine
wind. However, if too much mulch is applied, it
or fir needles as mulch over bare soil and
may hinder the revegetation success of seeds
have conifers on your property, you face the
for the same reason it hinders weed growth:
challenge each summer of raking off excess
the sprouts cannot penetrate the thick mulch.
needles that have fallen since the snowpack
Thicker layers of organic mulch may also
has melted. Those needles that have been
present an increased fire risk.
matted down by snow for one or more winters
often knit together as they decompose,
Mulch Maintenance
creating good erosion control cover and
Because of their ability to decompose into the
adding organic matter to your topsoil as the
soil, organic mulches need to be maintained
old needles decay. Only newly fallen needles
yearly to be effective. The best maintenance
should be removed, and only when needle
method is to apply mulch in the spring after
thickness exceeds 2 inches. Never rake down
the snow has melted, and then supplement
to bare soil. (See next section.)
with some more mulch before the snow falls
Chapter 6: Vegetation and Mulch ~ 53
Pine Needle Do’s
DO place “inorganic mulch” (gravel or stone)
next to wooden or flammable structures and
under decks.
DO rake up needles accumulating on hard
surfaces such as pavement, decks, rooftops
and gravel-covered surfaces
◄defensible space►
DO revegetate and mulch an area if you have
removed all pine needles to bare soil.
DO leave 2 inches of the dark, organic layer
A note on fire safety and
defensible space
Because we live in an urban forest
environment, there is a definite threat from
wildfire. Follow these simple guidelines to
reduce the risk on your property. If vegetation
is properly maintained, wildfire threat can be
substantially reduced.
Guidelines for fire defensible space for residential properties
(See Chapter 5 in the Home Landscaping
Guide for details)
▄ Choose less flammable vegetation and
inorganic mulch near your home.
▄ Cut down dead trees and shrubs but
leave the roots in place. *
▄ Eliminate low-lying branches and stems.
▄ Move firewood piles away from the house.
▄ Cut back dried grass.
▄ Break up dense vegetation. *
▄ Pick up fallen branches and pinecones,
leaving pine needles to decompose and
create mulch.
*Contact TRPA for tree cutting/limbing and
vegetation removal permits and restrictions.
See “Tree Removal and Tree Protection” in
Appendix E.
of decaying plant matter such as leaves and
needles known as the duff layer.
Pine Needle Don’ts
DON’T rake ALL pine needles, leaving bare,
unvegetated and non-mulched soil.
DON’T rake pine needles after the beginning
of autumn rains. The snow pack helps pine
needles decompose into natural mulch.
DON’T apply pine needles within five feet of
any structures. Use non-flammable, inorganic
(gravel or stone) mulch or hard surface in
these areas.
If you are creating a native or ‘natural’
landscape and have amended the soil and
added adequate mulch, your irrigation output
will be substantially reduced.
The main principle in these types of
landscapes is to add water slowly and
penetrate to the root zone and below.
According to the USDA/Natural Resources
Conservation Service (NRCS), most of Tahoe’s
soils can only hold ½ inch of water in the top
12 inches of soil. Therefore, by testing your
irrigation system, you can determine how long
it takes to deliver a ½ inch of water to the
revegetation project and only irrigate for that
amount of time.
54 ~ Chapter 6: Vegetation and Mulch
If ponding or runoff occurs before you
Table 1. Inches of Water Used by Grass in the Lake Tahoe Basin
have applied ½ inch of water, program your
systems to run “on,” until ponding or runoff
begins, and then “off,” for a couple of hours,
and then “on” for the same on time as before.
Continue the “on/off” cycled irrigation until
you have applied approximately ½ inch of
water. The wait time is very important. It allows
the water to move through the soil profile
Utility District ( In
before more is added. This prevents runoff
Nevada, contact your local water supplier or
and allows for deeper watering, which also
encourages deeper rooting.
Please refer to Chapter 4 of the Home
Just measure how long it takes your sprinkler
Landscaping Guide for Lake Tahoe and
system to apply a ½ inch of water, then water
Vicinity for more information on setting up
your lawn for that amount of time:
Hydrozones, installing irrigation systems, and
maintaining irrigation systems for efficient
▄ 2 times a week beginning in April and
water management.
▄ 3 times a week, where needed, May
These are the basic principles you need to
know in order to optimize your lawn watering.
▄ How much water your sprinkler system
through mid–September.
Fertilizers, soil amendments
Please refer to Chapter 9 of the Home
▄ How much water your soil can hold.
▄ Where grass roots absorb most of their
Landscaping Guide for Lake Tahoe and
▄ How much water your grass uses at
your landscape properly so that you are not
different times of the year.
Vicinity for specific information on fertilizing
polluting ground water or contributing to Lake
Tahoe’s declining clarity! As a rule of thumb,
apply fertilizer only when it is needed in spring
Good watering and lawn care tips
▄ Water early in the morning, preferably
before 7AM.
and fall, and then sparingly—at about half to
three quarters the recommended rate found
on the label. Be sure to water slowly and
▄ Know your public utility district rules for
deeply following the application. Watering
watering landscapes.
▄ Keep your irrigation schedule flexible for
moves the fertilizer into the root zone of the
periods of rain or excessive heat.
▄ Use automatic controllers to improve
soil so the plant can use it. Secondly, without
water, the fertilizer may burn the plants
wherever it contacts tissue.
water conservation.
Note: Never fertilize in the shorezone or near a
A note on water restrictions
Water restrictions may be enforced during the
dry summer months. It is important to follow
the guildelines established for your area.
Regulations in California can be obtained
from the South Tahoe Public Utility District
( or the North Lake Tahoe Public
Chapter 6: Vegetation and Mulch ~ 55
Sierra Valley Farms
Attn: Gary Romano
Home Landscaping Guide for Lake Tahoe and
1329 County Road A-23
Vicinity. Revised 2002.
Beckworth, CA 96129
University of Nevada Cooperative Extension.
(530) 832-0114
Sunset Western Garden Book
(775) 746-3681
Lane Publishing Co., Menlo Park, CA.
Available at most bookstores and home
Applewood Seed Co.
centers. Detailed information on plants
Arvada, CO
suited to the western climate, and specific to
climate zones.
(303) 431-7333
A Guide to Estimating Irrigation Water Needs
Cornflower Farms Inc.
of Landscape Plantings in California
California Native and Water Wise Plants
Great for contractors looking to reduce costs
Elk Grove, CA
associated with over watering. This book is
[email protected]
free by contacting the Department of Water
(916) 689-1015
Resources at (916) 653-1097.
Weeds of the West
Resilient Perennials for Pathways and Borders
The Western Society of Weed Science in
Cooperation with the Western United States
Land Grant Universities Cooperative Extension
Services. Revised 1992.
Educational Classes:
Truckee Meadows Community College: (775)
Botanical and Demonstration Gardens:
Lake Tahoe Community College
(offers Irrigation Management classes and
BMP Demo and Native Plant Garden,
other related courses.)
One College Drive, South Lake Tahoe, CA
Lake Tahoe Community College: (530) 541North Lake Tahoe Demonstration Garden
Incline Village, NV
(offers Landscape Architecture classes and
other related courses.)
Northern Nevada Native Plant Society Garden
Department of Wildlife
CalFlora Database
1100 Valley Rd. Reno, NV
Seed Sources:
California Native Plant Society
Comstock Seed
Locally collected seed source
Gardnerville, NV
California Department of Agriculture, Weed
56 ~ Chapter 6: Vegetation and Mulch
Chapter 7
Maintenance and Monitoring
Basic concepts of BMP
o maintain the effectiveness of Best
Management Practices (BMPs), regular
inspections and maintenance are
essential. Generally, inspection and
maintenance of BMPs can be categorized into
two groups--expected routine maintenance
and non-routine (repair) maintenance.
Routine maintenance refers to checks
performed on a regular basis to keep the
BMP in good working order and aesthetically
pleasing. In addition, routine inspection
and maintenance is an efficient way to
prevent potential nuisance situations (odors,
mosquitoes, weeds, etc.), reduce the need for
repair maintenance, and reduce the chance
of polluting storm water runoff by finding and
correcting problems before the next rain
event. Routine maintenance also refers to
removing the buildup of sediment in certain
types of BMPs, cleaning out proprietary vaults
with a vactor truck, and sweeping parking lots
and road surfaces.
Non-routine maintenance refers to any
activity that is not performed on a regular
basis. This type of maintenance could include
major repairs after a violent storm, extended
rainfall, or a heavy winter, or replacement and
redesign of existing BMPs.
Local ordinance requirements
The TRPA Code of Ordinances Subsection
25.8 requires BMPs to be maintained. This
subsection states:
“Maintenance of BMPs: BMPs shall be
maintained to ensure their continued
In order for Best Management Practices
to remain functional, they must be monitored
and maintained for effectiveness. For a
residential BMP such as a gravel infiltration
trench, the homeowner should observe the
trench during a storm to see if it is still infiltrating
water. Gravel infiltration trenches can be
maintained by the homeowner by removing
sediment and debris that accumulates to
ensure the trench’s effectiveness.
For a commercial site, monitoring may
include storm water quality sampling to ensure
that water leaving pre-treatment systems
falls within TRPA’s standards for surface or
groundwater discharge. Maintenance in
Chapter 7: Maintenance and Monitoring ~ 57
this example would include the commercial
Source control will prevent excessive
property owner having a storm water pollution
maintenance. Source control refers to the
prevention plan which incorporates routine
practice of making sure that all soils near the
servicing of the storm water pretreatment
BMP are stabilized and not prone to erosion.
system and the parking areas.
Bare dirt can easily be transported from one
Best Management Practices that are no
on-site location to the BMP location and cause
longer functioning are out of compliance
clogging or inefficiency. For example, if the
with local ordinance requirements, ultimately
soil on the edge of a driveway is not stabilized
rendering the accompanying BMP Certificate
with vegetation and mulch and retained
of Completion void.
with a border, or the border is old and not
Checking BMPs
functioning, the soil can be washed down
onto the paved surface, through the slotted
BMPs must be checked regularly to make sure
drain and into the drywell. This can clog
they are functioning properly. BMPs should be
the drywell and prevent proper functioning,
monitored at least every year and perhaps
perhaps even after the first heavy storm (see
more often depending on the type of BMP
photograph below).
as well as individual site circumstances. Over
time, BMPs become clogged or damaged,
which decreases effectiveness and
functionality. Maintenance can be as simple
When installing any BMP, proper planning
as raking the accumulated debris away
will save time, money and headaches later.
from the entrance to a drywell after a heavy
Accessibility to perform maintenance is an
downpour, or can be as complex as digging
important factor to consider.
up and replacing an entire subsurface drain
A simple practice that makes some BMPs
that is clogged due to improperly installed
easier to maintain is to install a border such as
wood, rock or bender board to help prevent
It is very important to keep in mind
that any debris/sediment cleaned out of a
Plan ahead when installing BMPs
for ease of maintenance
BMP should be disposed of properly, either
transported off-site to a TRPA approved
location, or contained and stabilized on-site
where it will be unaffected by wind and/or
Poor erosion
control and
an inefficient
retaining border
allows sediment
to spill onto
driveway, which
will prematurely
clog the
58 ~ Chapter 7: Maintenance and Monitoring
sedimentation and to keep gravel in place.
Hint: Make sure that when the border is
installed, that it does not prevent any inflow of
water or divert water off site.
Filter fabric is another tool that can be
used to prevent the need for completely
removing a BMP for cleaning. Filter fabric
allows water to infiltrate into the BMP while
preventing sediment particles from entering,
thus allowing for easier cleaning. Be sure to
clean the top layer of fabric thoroughly or
replace it with new filter fabric periodically,
because it can become clogged over time.
The amount of time between cleanings varies
according to how much sediment input is
occurring and according to the size of the
sediment particles.
Maintenance of infiltration and
conveyance systems
Perforated Drain Pipes
In order for a typical infiltration system to work
Planning a perforated drainpipe installation
appropriately for the long term, it should be
includes designing an effective cleanout
installed to allow for easy maintenance. The
for sediment and debris. A poorly installed
following discussions will give examples of
drainpipe that lacks a cleanout will end up
different types of infiltration systems and how
clogged and will no longer function to control
each should be inspected and cleaned
runoff. A nonfunctioning system will result in
regularly to maintain their effectiveness.
stormwater runoff bypassing this infiltration
system and contributing to runoff and erosion,
Gravel Trenches and Drywells
potentially causing expensive water damage
To inspect gravel trenches or gravel drywells,
to properties.
observe the BMP and notice if sediment and
Proper installation of a cleanout will
debris has accumulated on top of the gravel
add life to the system and allow for easy
and in the spaces between each rock. If
maintenance. A properly installed cleanout
debris such as pine needles, leaves and/or
includes a removable cap and access to both
twigs are only fresh on the surface, simply rake
ends of the system, which will allow the system
them off to prevent clogging. However, over
to be cleaned when sediment or debris has
time, the spaces between the gravel that
accumulated. See the Runoff & Infiltration
normally store runoff until it can soak into the
Section for more details.
ground will become clogged and the BMP
will no longer function. The end result of this
Slotted Drains
occurrence is runoff not entering the BMP, but
Slotted drains are used to divert and
rather leaving the property. The frequency
convey driveway runoff to a properly sized
of clogging varies according to how well
infiltration system. Slotted drains should have
source control is occurring, site topography,
removable grates to allow access for cleaning
and landscape features, but can occur in
accumulated debris and sediment that block
one year’s time if conditions allow for it. Once
the flow of water. Slotted drains generally
Slotted channel
the gravel is clogged, this BMP is considered
need to be cleaned twice a year, once in the
drain with
inadequate and out of compliance. The
spring after snowmelt and once in the fall prior
next step is to clean the gravel and restore
to snowfall. These systems should be swept or
grates for
the functionality of the BMP, which is briefly
vacuumed out rather than flushing out debris
described below.
Sifting to remove debris and replacing the
cleaned gravel is the best way to maintain this
BMP. Use a medium sized mesh that is small
enough to hold the gravel, but large enough
to allow the dirt and debris to fall through.
Hint: Make sure to sift over a wheel-barrow,
flower bed or other contained area so that
the fine soil particles will not be eroded away
by wind or water. If sifting over a driveway,
sweep up the dirt and debris thoroughly and
stabilize onsite. Once the gravel is sifted and
cleaned as much as possible, return it to its
original location.
Chapter 7: Maintenance and Monitoring ~ 59
with high-pressure washers or water, which will
clogged and nonfunctional. In the event that
just prematurely clog the infiltration system.
the filter fabric becomes clogged, it must be
The point where runoff flows from the
rinsed and cleaned to maintain the flow of
slotted drain into an infiltration system can also
water into the infiltration system. Check the
get clogged with dirt and debris and should
inlet to the infiltration system often to ensure
be checked for functionality. This area must
that it is providing adequate flow into the
be cleaned to ensure that the concentrated
storage chamber(s).
runoff flowing within the slotted drain can
Gravel covering the filter fabric over the
infiltrate into the infiltration system. If cleared
entrance to the infiltration system may also
of any loose surface debris on a regular
become clogged. See the above section on
basis, proper infiltration can be maintained.
maintaining gravel trenches for a description
If heavily cemented with long-term build-up,
of how to maintain gravel infiltration areas.
sift gravel and remove build-up (as described
Also be aware of the interior storage area
above for gravel mulch and trenches) to
of the infiltration system. Is it filling up with
ensure effectiveness. See Paved Driveways
sediment and reducing the system’s storage
Section for more details.
capacity? If this is occurring, the entire
infiltration system may need to be removed,
Prefabricated drywells and trenches
cleaned and replaced. If infiltration systems
Prefabricated drywells and trenches
are installed to include a sediment clean-out
are infiltration systems that are filled with
before the stormwater reaches the system,
manufactured stormwater storage units (see
they will be more easily maintained in the
Runoff & Infiltration Section). These systems
long term. See the Runoff & Infiltration Section
catch and store runoff onsite, eventually
for more information on installing infiltration
letting it seep into the surrounding soil.
Prefabricated drywells and trenches require
maintenance to prevent clogging so that
Roof Gutters
runoff can continue to flow into the storage
Roof gutters capture roof runoff and convey
it to an infiltration system where the water
Prefabricated infiltration systems may
sediment trap
have an inlet pipe to direct stormwater runoff
maintenance in order to function properly.
with large
underground. The inlet may be covered with
Careful cleaning of debris from the gutter
grate is easily
filter fabric to prevent sediment from filling the
and off the roof will allow runoff to reach the
system, but this filter fabric may itself become
infiltration system. If the gutter is clogged,
can be stored. Gutters require regular
runoff can spill over the gutter and create
dripline erosion. Removing pine needles and
other debris from the gutter and the roof is also
a positive step toward creating fire defensible
space (see Chapter 5 in Home landscaping
Guide for Lake Tahoe and Vicinity).
Vegetation and Buffer Strips
Planting native or adapted vegetation as a
BMP may be the simplest and most effective
means to control erosion. Besides controlling
erosion, vegetation adds aesthetic value to
a property, provides habitat for wildlife and
60 ~ Chapter 7: Maintenance and Monitoring
provides a buffer strip to collect sediment and
Organic Mulch
Organic mulch, such as pine needles, bark
Maintaining vegetation is key to its long-
chips or shredded cedar, is spread over bare
term success. If vegetation is neglected or
soil to help control wind and water erosion.
mistreated it may die, which eliminates its
Over time, foot traffic, pet traffic, and natural
effectiveness, potentially making the property
decomposition will wear away organic mulch,
out of compliance with local BMP ordinances.
creating exposed bare soil that is vulnerable
(See Chapter 6, Vegetation & Mulch.)
to erosion. It is important to continually add
If vegetation is used as a BMP under a
organic mulch to areas that have worn away,
dripline to control the concentrated impact
blown away or decomposed (see Vegetation
of roof runoff, it is important to make sure
& Mulch Section, p. 53). Allowing pine needles
the vegetation is dense and strong enough
to accumulate to a depth of two inches from
to withstand the runoff impact. Look to see
the surrounding trees or spreading two inches
which plants are responding and healthy.
of wood chips will help control erosion on
Perhaps these plant species should be
slopes less than 33%.
encouraged in other areas. Look to see which
plants are sparse and dying. Perhaps these
Detention Basins
plant species should be replaced and/or
Routine inspection and maintenance of
moved to other areas. Look to see if there
detention basins is essential to their continued
is exposed bare soil between plants. Bare
effectiveness. Basins should be inspected after
areas away from structures should always be
each storm event to ensure proper drainage
covered with a 2 inch thick layer of organic
from the collection pool, and to determine the
mulch. However, bare soil areas within three
need for structural repairs. Detention basins
to five feet of building foundations should be
should be designed to allow for easy access
protected using a non-combustible mulch, i.e.
by maintenance personnel. Sediment should
gravel, to enhance the defensible space.
be removed from the basin when its storage
Another great way to maintain healthy
capacity is diminished. Trash and debris that
vegetation is to install and maintain a raised
accumulate around detention basins should
planting box to contain soil and reduce runoff
be removed promptly after rainfall events.
in vegetated areas. HINT: Make sure that any
Remember to dispose of the debris and soil
plants used next to or near structures have
a low fire hazard rating. (See Chapter 5 and
Chapter 7 in Home Landscaping Guide for
IMPORTANT: Do not dump removed sediment
Lake Tahoe and Vicinity).
and debris into an area that could connect
Native and adapted species, if chosen
or wash to a waterway emptying into Lake
correctly for site conditions, need less water
Tahoe. This defeats the whole purpose of
and less fertilizer to live in Lake Tahoe’s
having a sediment basin!
harsh growing environment. Limit the use
of non-native plants since they will need
greater amounts of fertilizer and water to
maintain their health. Use low content or no
phosphorus fertilizers, and low-flow irrigation
systems to maintain plants. See Chapter 12 in
the Home Landscaping Guide for Lake Tahoe
and Vicinity for more information.
Chapter 7: Maintenance and Monitoring ~ 61
Mechanical Treatment Devices
ultimately bypass treatment. Frequent clean-
Mechanical treatment devices, or sand/oil
out can retain the designed volume within
separators, are typically installed as pre-
the device’s sump, thus allowing for optimal
treatment devices at commercial sites or
larger scale, high-traffic parking lot areas.
There are a wide variety of mechanical
These mechanical treatment devices can
treatment devices on the market. These
be strategically located in areas where large
products vary from baffle-type systems to
amounts of trash and coarse debris and high
swirl separators, or hydrodynamic structures
concentrations of oil, grease, gasoline, heavy
(see figure below). Swirl separators are
metals and other pollutants are a problem.
modifications of the traditional oil-grease
Sand/oil separators should discharge to an
separator and include an internal component
infiltration system (i.e. drywell, infiltration trench
that creates a swirling motion as stormwater
or detention basin) for final treatment and
flows through a cylindrical chamber.
nutrient removal.
Typical maintenance of sand/oil
No matter what type of mechanical
treatment device that is installed, it is essential
separators includes: trash removal if a screen
to work closely with the manufacturer and
or other debris capturing device is used,
installer to create an effective maintenance
changing of oil absorbent pillows or cartridges
and monitoring plan to ensure the systems
and removal of sediment and sludge using
proper functionality.
a vactor truck. Maintenance should include
This mechanical
device needs to
be maintained
to remain
keeping a log of the amount of sediment
collected and the date of removal. Some
cities have incorporated the use of GIS
systems to track sediment collection and to
optimize future sand/oil separator cleaning
Keep in mind that when the sump within
the device begins to reach capacity, storm
flows can re-suspend sediments trapped in
the mechanical treatment device that will
62 ~ Chapter 7: Maintenance and Monitoring
Mechanical treatment devices such as
sediment traps need to be monitored visually
to determine when clean out is necessary.
Maintenance activities and schedules for urban infiltration Best Management Practices
(Adapted from CWP, 1998)
Management Practice
Maintenance Activity
Infiltration Trench or Drywell
▄ Cleaning and removal of debris after major storm
events; (>2” rainfall)
Annual or as needed
▄ Mowing and maintenance of upland vegetated areas
▄ Sediment cleanout
▄ Repair or replaacing of stone aggregate
▄ Maintenace of inlets and outlets
Infiltration Basins
▄ Removal of accumulated sediment from sediment
storage areas when 50% of the original volume has
been lost
4-year cycle
▄ Cleaning and removal of debris after major storm
events; (>1” rainfall)
Annual or as needed
▄ Irrigation, mowing and maintenance of vegetated
▄ Sediment cleanout
Dry Swales, Grassed Channels,
▄ Removal of accumulated sediment from sediment
storage areas when 50% of the original volume has
been lost
3- to 5-year cycle
▄ Mowing and litter/debris removal
Annual or as needed
▄ Stabilization of eroded side slopes and bottom
▄ Nutrient and pesticide use management
▄ Dethatching swale bottom and removal of thatching
▄ Disking or aeration of swale bottom
▄ Scraping swale bottom and removal of sediment to
restore original cross section and infiltration rate
5-year cycle
▄ Seeding or sodding to restore ground cover (use proper
erosion and sediment control)
Water spreading area
▄ Mowing and litter/debris removal
Annual or as needed
▄ Nutrient and pesticide use management
▄ Aeration of soil on the infiltration area
▄ Watering of plant material
▄ Repair of eroded or sparse grass areas
Vegetated Above Ground Infiltration
▄ Repair of erosion areas
Biannual or as needed
▄ Mulching of bare soil areas
▄ Removal and replacement of all dead and diseased
▄ Watering of plant material
▄ Removal of excessive mulch and application of a new
layer if necessary
Chapter 7: Maintenance and Monitoring ~ 63
Center for Watershed Protection (CWP).
1998. Costs and Benefits of Storm Water BMPs:
Final Report 9/14/98. Center for Watershed
Protection, Ellicott City, MD.
EPA Website at
For more information, go to the website listed
64 ~ Chapter 7: Maintenance and Monitoring
Chapter 8
he installation of Best Management
before February 10, 1972 or created after
Practices (BMPs) may require the
February 10, 1972 pursuant to either TRPA
property owner to obtain permits from
Ordinance No. 4, as amended, or other TRPA
the Tahoe Regional Planning Agency
approval, that prevents normal precipitation
(TRPA) and/or the local jurisdiction where the
from directly reaching the surface of the land
property is located (City of the South Lake
underlying the structure, improvement or
Tahoe, Washoe County, El Dorado County,
covering. Such structures, improvements and
Placer County or Douglas County). The need
coverings include but are not limited to roofs,
to obtain permits may be initiated due to
decks, surfaces that are paved with asphalt,
the amount of excavation being performed,
concrete or stone, roads, streets, sidewalks,
paving of unpaved driveways, the installation
driveways, parking lots, tennis courts, patios.
of BMPs in easement areas, the removal of
trees or other vegetation, landscaping or
Soft Land Coverage: Lands so used before
issues concerning land coverage on the
February 10, 1972, for such uses as for the
subject property. This chapter is intended to
parking of cars and heavy and repeated
provide a general overview of situations where
pedestrian traffic that the soil is compacted
permits are required when installing BMPs. This
so as to prevent substantial infiltration. A
chapter should not be construed to cover
structure, improvement or covering shall not
every scenario or be a comprehensive guide
be considered as land coverage if it permits
to permitting. If additional questions are
at least 75 percent of normal precipitation
raised beyond what is provided for in this
directly to reach the ground and permits
chapter, please call either TRPA at (775) 588-
growth of vegetation on the approved
4547 or your local jurisdiction as appropriate.
species list.
Excess Land Coverage: The amount of
Hard Land Coverage: A man-made structure,
improvement or covering, either created
legal existing land coverage on the property
that exceeds the base land coverage for
Chapter 8: Permitting ~ 65
the parcel based on the Land Capability
Land Capability District: A soils unit designated
system developed by Dr. R.G. Bailey. If the
on the adopted TRPA land capability map
land coverage has been legally established
and denominated by a numerical rating
pursuant to the definitions of Hard and Soft
of one through seven, e.g. Land Capability
Land Coverage above, the coverage is
District 1. The system devised by Dr. Robert
often referred to as “grandfathered” land
G. Bailey sets forth land coverage limitations
for construction on parcels based on their
geological characteristics and their suitability
Allowable Land Coverage: The amount of
for development. TRPA has these maps.
allowable land coverage for most parcels
with existing development (exclusive of
Individual Parcel Evaluation System (IPES):
residences approved under the Individual
Since January 1, 1989, the IPES system has
Parcel Evaluation System (IPES) is based on
been in place for the review of single family
the Bailey Land Classification System. The
dwelling applications. The IPES score is
Bailey System rates land based on sensitivity
generated by evaluating the property-specific
to development as determined by soil type
environmental characteristics using eight
and slope: Classes 1, 2, and 3 are defined
evaluation criteria, (Relative Erosion Hazard,
as “sensitive” and Classes 4, 5, 6, and 7 are
Runoff Potential, Degree of Difficulty to Access
defined as “non-sensitive”. Land Capability
the Building Site, Parcels Requiring Access
District 1b, also known as Stream Environment
Through a Stream Environment Zone, Stream
Zone (SEZ), is the most environmentally
Environment Zone, Condition of Watershed,
sensitive land capability district. In general, a
Ability to Revegetate, Need for Water Quality
SEZ is an area which owes its biological and
Improvements in Vicinity of Parcel and
physical characteristics to the presence of
Proximity to Lake Tahoe) which determines the
surface or ground water. Each of the seven
suitability of the parcel for development. The
land capability classes has a corresponding
IPES system sets forth land coverage limitations
percentage of allowed land coverage:
in addition to a numerical score which
determines its eligibility to be built upon.
“Exempt” Projects: If a project is considered
Land Capability District
Land Coverage Allowed
Exempt pursuant to Chapter 4 of the TRPA
Code of Ordinances, then the project does
not require review by TRPA or a TRPA permit.
1 (a,b,c)
However, permits may be required from the
local jurisdiction where the property is located.
“Qualified Exempt” Projects: If the proposed
project is considered Qualified Exempt
pursuant to Chapter 4 of the TRPA Code
of Ordinances, then the applicant must file
a Qualified Exempt Declaration form that
describes the proposal. Additional permits
may be required from the local jurisdiction
66 ~ Chapter 8: Permitting
where the property is located.
When are permits needed?
▄ The grading, excavation, or filling does not
Grading and Excavation
occur during periods of precipitation, or
Please note that any amount of grading,
when the soil is covered with snow, or is in
excavation, or filling in a stream environment
a saturated, muddy or unstable condition;
zone (SEZ), a flood plain, or in the shorezone
is generally prohibited. In addition, proper
▄ The grading, excavation, or filling is not
erosion control measures, such as erosion
part of a series of excavations that, when
control fences or fiber logs, must be in place
viewed as a whole, would require a TRPA
before any grading, excavation, or filling is
initiated. General excavations that meet the
following criteria may either be Exempt or
Grading, Excavation, or Filling Greater Than 7
Qualified Exempt.
Cubic Yards:
Grading, Excavation, or Filling Less than 3
7 cubic yards of soil requires a TRPA Permit
Cubic Yards:
and may require a permit from the local
Grading, excavation, or filling less than 3 cubic
yards is considered Exempt by TRPA, provided
Grading, excavation, or filling greater than
▄ The associated grading, excavation, or
Landscaping and gardening is considered
filling does not exceed 3 cubic yards
▄ The work is completed within 48 hours;
▄ The site is stabilized to prevent erosion;
▄ The grading, excavation, or filling does
Exempt by TRPA, provided that:
not occur during periods of precipitation,
when the site is covered with snow, or is in
a saturated, muddy or unstable condition;
▄ The grading, excavation, or filling is not
part of a series of excavations that, when
viewed as a whole, would require a TRPA
Landscaping and Gardening:
▄ The landscaping is in accordance with
the TRPA Handbook of Best Management
Practices requirements for fertilizer use and
the TRPA plant list;
▄ There is no creation or relocation of land
coverage (e.g., pathways);
▄ Any associated grading, excavation, or
filling is Exempt (i.e. does not exceed three
cubic yards); and
▄ The natural slope of the site is maintained
(i.e., no terracing or recontouring).
Grading, Excavation, or Filling Less Than 7
Cubic Yards:
Grading, excavation, or filling less than 7 cubic
yards is considered Qualified Exempt by TRPA,
provided that:
▄ The grading, excavation, or filling occurs
between May 1st and October 15th.
▄ The grading, excavation, or filling occurs
on high capability land (Class 4-7) or on a
parcel with a buildable IPES score;
▄ The site is stabilized within 48 hours to
prevent erosion;
Chapter 8: Permitting ~ 67
Residential Driveways
In calculating the number of spaces
There are many different scenarios
needed on site, please be aware that
encountered when installing Best
TRPA recognizes existing garages as one
Management Practices for driveways. Most
on-site parking spot (regardless of the size
driveway situations should fit into one of the
of the garage). In order to install a new
categories below, however, if additional
driveway or parking pad, property owners
questions arise, please contact the TRPA
must either: 1) have the allowable land
offices at (775) 588-4547.
coverage on site to install a driveway, 2)
▄ If the property owner is simply constructing
relocate legally existing land coverage
on-site, 3) transfer in the minimum amount
overlays upon existing paved surfaces,
of land coverage based on Subsection
and is neither creating nor relocating
20.3.B(7) of the TRPA Code of Ordinances
coverage on site, this activity is
through a TRPA permit, or 4) in some cases,
considered Exempt by TRPA. Check with
parking areas may be designated in the
the local jurisdiction.
right-of-way if there is no other feasible
▄ To pave a dirt driveway, the property
owner must complete a Driveway Paving
alternative and the local jurisdiction or
highway department provides approval.
The fourth option should be explored, only
Application. Driveway Paving Applications
when no other option is available. In order
can be completed at the City of South
to determine whether a property fits any
Lake Tahoe, El Dorado County, Placer
of the above criteria, a land coverage
County and TRPA.
verification and land capability verification
or a site assessment is required. These
The paving application is intended to
applications should be submitted to TRPA
provide “the minimum driveway access
or the local jurisdictions as appropriate.
and parking” (approximately 400 square
feet). Generally, if there is a garage or
There are several other standards that must
other parking structure, the area to be
be used in designing residential driveways.
paved should be located in front of
First, driveways must be consistent with the
the garage or other parking structure,
driveway standards found in Chapter 24
for access. If the property owner would
of the TRPA Code of Ordinances and local
like to have additional compacted
regulations. Secondly, in many cases parking
areas verified as “legal existing land
barriers must be installed to prevent parking or
coverage” pursuant to Chapter 2 of
the storage of equipment on unpaved areas.
the TRPA Code of Ordinances, beyond
Split-rail fences, wood bollards or boulders are
what is permittable in the Driving Paving
often used as parking barriers. Split-rail fences
Permit, the property owner would need
or wood bollards are preferable to boulders
to submit a land coverage verification or
because often boulders can be moved too
site assessment application to TRPA or the
easily. If you have additional questions on
local jurisdiction (as applicable).
driveway standards, please contact TRPA or
▄ Some residential properties do not
have an existing driveway on site. Most
local jurisdictions require that property
owners have two on-site parking spaces.
Contact the local jurisdiction for details.
68 ~ Chapter 8: Permitting
your local jurisdiction.
Paving of parking lots and driveways for com-
▄ Installations where the wall is 3 feet
mercial, tourist accommodation, recreation
in height or taller, which need to be
and public service properties
designed by an engineer licensed in the
Depending on size and use, these projects
state where the work is being performed;
generally require the installation of sand/oil
separators to remove pollutants and sediment
that is generated from stormwater runoff. In
▄ Retaining walls installed that alter the
natural slope of the site.
addition these projects generally require a
substantial amount of grading and therefore
There may be other instances where TRPA
a TRPA permit is required for these activities.
permits are required. Please contact TRPA at
Such projects usually require plans stamped
(775) 588-4547 to determine if a permit will be
by an engineer licensed in the state where
required for your project.
the work will be performed. Projects must be
designed to meet all TRPA and County or
Your local jurisdiction may also require the
submittal of a permit and engineered plans.
City standards for parking area and driveway
design. These standards refer to the slope of
Shoreline protective structures
the graded area, vegetation components,
Shoreline protective structures are used to
driveway width standards, parking space
prevent erosion of the backshore of Lake
design as well as other property specific
Tahoe. These structures require the submittal
requirements. TRPA requirements for driveway
of a TRPA Shorezone Application to TRPA
installation are found in Chapter 24 of the
for review and approval. These structures
TRPA Code of Ordinances. In addition, the
must be designed by a qualified professional
Community Plan Area Statements for each
engineer and meet the standards found
jurisdiction may include additional design
in Subsection 54.13 of the TRPA Code
requirements for the design of driveway and
of Ordinances in terms of the necessary
parking areas. These documents are available
environmental findings and design criteria. In
for viewing at the TRPA offices or at your local
most cases the shorezone protective structures
planning department. Parking areas will
must be designed so that they are sloping
require a permit from TRPA as well as the local
and permeable. Additional permits may
jurisdiction (City of South Lake Tahoe, Washoe
be required from such agencies as Nevada
County, Placer County, Douglas County, or El
State Lands, the California State Lands
Dorado County).
Commission, the U.S. Army Corps of Engineers,
the California Regional Water Quality Control
Retaining walls
Board- Lahontan Region and your local
TRPA does not generally require permits for the
installation of retaining walls, however there
are some exceptions. Some cases that may
require permits are:
▄ Large retaining walls that are visible from
scenic corridors (i.e. Lake Tahoe, Highway
89 and 50);
▄ Installations that require the excavation of
greater than 3 cubic yards of dirt;
▄ Installations that require the removal of
any trees or vegetation;
Chapter 8: Permitting ~ 69
70 ~ Chapter 8: Permitting
Aquifer: An underground bed or layer that
Eutrophication: Degradation of water quality
contains fresh water in sufficient amounts to
due to enrichment by nutrients, primarily
yield useful quantities to wells and springs.
nitrogen and phosphorus, resulting in excessive
plant (principally algae) growth and decay.
Basin: A region drained by a single river
Low dissolved oxygen and reduced water
system. May also refer to an above-ground
clarity are common consequences.
infiltration system.
Filter Fabric: A permeable textile of relatively
Best Management Practice: Structural or
small mesh that is used to allow water to pass
non-structural practices proven effective in
through while causing the sediment to settle
managing surface-water runoff and reducing
water pollution from soil erosion and other
nonpoint sources.
Filter Strip: A long, narrow portion of
vegetation used to retard water flow
Culvert: A short, closed (covered) conduit or
and collect sediment for the protection
pipe that passes storm water runoff under an
of watercourses, reservoirs, or adjacent
embankment, usually a roadway.
Discharge: The volume of water and
Grading: The cutting and/or filling of the land
suspended sediment in surface water, that
surface to a desired slope or elevation.
passes a given location within a given period
of time. Rivers are usually measured in Cubic
Groundwater: That portion of the water
Feet Per Second (CFS). Storm water discharge
beneath the surface of the earth that can
can be measured in Gallons Per Minute
be collected with wells, tunnels, or drainage
galleries, or that flow naturally to the earth’s
surface via seeps or springs.
Easement: A right by express or implied
agreement which one has in the land of
Infiltration: The penetration of water through
another. It is either for the benefit of land, such
the ground surface into sub-surface soil.
as right to cross A to get to B, or as a public
utility easement.
Inlet: An entrance into a ditch, storm sewer or
other waterway.
Erosion: Detachment and movement of rocks
and soil particles by gravity, wind and water.
Non-Point Source (NPS) Pollutants: Pollutants
Often the eroded debris (silt or sediment)
from many different sources. NPS pollution is
becomes a pollutant via storm water runoff.
caused by rainfall or snowmelt moving over
Erosion occurs naturally, but can be intensified
impervious surfaces or the ground. As the
by land-clearing activities such as farming,
runoff moves, it picks up and carries away
urban development, road building, and
natural and human-made pollutants, finally
timber harvesting.
depositing them into lakes, rivers, wetlands,
costal waters, and even underground sources
of drinking water.
Glossary ~ 71
NPDES: “National Pollutant Discharge
Right of Way: A strip of land which is uses as a
Elimination System” – the name of the surface
roadbed, either for a street or railway. The land
water quality program authorized by Congress
is set aside as an easement. May also be used
as part of the 1987 amendment to the Clean
to describe the right itself to pass over the land
Water Act. This is the EPA’s program to control
of another.
the discharge of pollutants to the waters of
the United States.
Riparian: Of, or pertaining to, rivers and their
Oil/Water Separator: A sub-surface
mechanical device which separates oil and
Runoff: That portion of precipitation or irrigation
grease from water entering the drain. This
water which fails to infiltrate soil and flows over
device requires regular maintenance to be
the surface to streams or water bodies.
Sanitary Sewer: A system of underground
Outfall: The point where wastewater or
pipes that carry sanitary waste or process
drainage discharges form a sewer pipe, ditch,
wastewater to a treatment plant.
or other conveyance to a receiving body of
Secondary Containment: Structures, usually
dikes or berms, surrounding tanks or other
Permeability: The characteristic of soil that
storage containers to catch spilled material.
allows water or air to move through it. Usually
described in inches/hours or inches/day.
Sediment Trap: A device for removing
sediment from water flows, usually installed at
Point Source Pollutant: Pollutants from a single
points of outflow.
identifiable source such as a pipe discharging
from a factory, refinery, or place of business.
Sedimentation: The process of depositing
soil, clay, sand, or other sediments that were
Pollutant Loading: The total quantity (mass) of
moved by the flow of water.
pollutants in storm water runoff. TDML (Total
Daily Maximum Loading) is the maximum
Stream Environment Zone: Land area adjacent
amount of pollutants that may be discharged
to stream, creek, wetland or lake that is
into a body of water according to EPA
influenced by flowing water or saturated soil
for at least a week during the growing season
each year. Can include riparian zones or
Recharge: Downward movement of water
streambeds that are dry except during rain or
through soil to groundwater.
snowmelt. SEZs protect the lake’s water quality
and their boundaries must be delineated by
Retention: A process that halts the
TRPA staff before construction is allowed near
downstream progress of storm water runoff.
them. Landscaping activities are prohibited in
This is typically accomplished using total
containment involving the creation of storage
areas that use infiltration devices, such as
Storm Drain: A drop inlet, channel or pipe that
dry wells, to dispose of stored storm water via
carries runoff from rain or snowmelt from a
percolation over a specified period of time.
roadside gutter to a river or lake without any
72 ~ Glossary
Stormwater: Precipitation that runs off
Urban Runoff: Stormwater from urban areas,
impervious land coverage (rooftops and
that tends to contain pollutants from vehicles
pavement) to storm drain systems during and
and industry along with pathogens, sediments
immediately following a storm event.
and nutrients.
Storm Water Facilities: Systems such as
Watershed: That geographical area which
watercourses, constructed channels, storm
drains to a specified point on a watercourse,
drains, culverts, and detention/retention
usually a confluence of streams or rivers. Also
facilities that are used for the conveyance
known as a drainage area, catchment or river
and/or storage of storm water runoff.
Stormwater Management: Functions
Wetlands: Areas that are regularly wet or
associated with planning, designing,
flooded and have a water table that stands
constructing, maintaining, financing, and
at or above land surface for a least part of the
regulating the facilities (both constructed and
growing season.
natural) that collect, store, control, and/or
convey storm water.
Swale: A linear depression, often constructed
of earth, lined with grass or gravel and used as
a conveyance for storm water. May also refer
to a shallow depression in a paved surface
designed to convey water.
Glossary ~ 73
74 ~
Appendix A: Priority Watershed Map
See reverse for
compliance dates
and contact
Appendix ~ All properties in the Tahoe Region are required to have BMPs installed.
Your property is located within a Priority One, Two or Three watershed.
The compliance dates are as follows:
Priority One - October 15, 2000
Priority Two - October 15, 2006
Priority Three - October 15, 2008
*BMP site evaluations will be completed at no charge until October 15, 2006.
For Commercial & Multi-Family Properties in NV and CA:
Tahoe Regional Planning Agency
P.O. Box 5310, 128 Market St
Stateline, NV 89449-5310
Phone 775-588-4547, ext. 202.
Fax: 775-588-4527
email: [email protected]
For Residential Properties in California:
Tahoe Resource Conservation District
P.O. Box 10529, 870 Emerald Bay Road
S. Lake Tahoe, CA 96158
Phone: 530-543-1501, ext. 6
Fax: 530-543-1660
email: [email protected]
For Residential Properties in Nevada:
Nevada Tahoe Conservation District
P.O. Box 4605, 297 Kingsbury Grade, Suite G
Stateline, NV 89449
Phone: 775-586-1610, ext. 28
Fax: 775-586-1612
email: [email protected]
~ Appendix
Appendix B: The Temporary BMP Hall of Shame, or How NOT to Install Temporary BMPs
Prevent this kind of erosion by keying the silt
fence at least 6 inches into the soil at the toe
of the slope.
Concentrated flow should not be directed onto
exposed, vulnerable slopes. More than one BMP
is needed here.
Tree protection fencing is not a
substitute for tightly woven silt fence
Appendix ~ Appendix B: The Temporary BMP Hall of Shame, or How NOT to Install Temporary BMPs
Tree protection fencing is
required to be fenced around
the fullest extent of the tree’s
The straw bales pictured are
not preventing sediment
from entering the drop inlet.
Furthermore, straw bales are
no longer recommended for
erosion control in the Lake
Tahoe Basin.
This silt fence is not properly
keyed in to a depth of at least
6 inches to prevent runoff
from leaving the disturbed
~ Appendix
CHART 1 - Soil Permability
Map Unit
Map Unit
Co *
Ev *
ShE *
SkF *
Gr *
TcB *
TcC *
TkC *
JbD *
JgC *
JhC *
JeB *
JeD *
* These soils may exhibit poor soil drainage characteristics that render infiltration systems inappropriate.
At Lake Tahoe, the terms Rapid, Moderate and Slow have been
used to define 13, 4 and 1 inch per hour soils respectively.
Appendix ~ Chart 2: Volume of Runoff From Impervious Surfaces
~ Appendix
Appendix D
Innovative Slope Stabilization Techniques
Biogeotechnical Construction
Based on the work of Andrew T. Leiser
some sites. The selection of spacing is a value
A brief description of several biogeotechnical
judgment at the present time.
construction methods will be given. Detailed
Wattling has several advantages: energy
construction methods are described in the
dissipation, temporary stabilization to allow
attached sample specifications and diagrams.
establishment of other vegetation, sediment
entrapment, and if of easy-to-root species,
the resulting plants become a part of the
The word “wattle” is derived form an Anglo-
vegetation component. The wattling may
Saxon word, “watel”, meaning interwoven
often be crowded out by more dominant or
twigs and hence a framework or hurdle of
better adapted species.
such. The word was adopted by Dr. Kraebel of
Wattling is indicated on basically stable
the US Forest Service in the 1930’s to describe
slopes that have a shallow, unstable surface
a process of erosion control where willow or
layer. It is also useful to repair curved slopes
other materials were placed in trenches, on
which are wide enough to allow bending of
contour, staked and partially covered with
the wattling bundles.
soil. The resulting “cable” of brush broke a
long slope in to a series of short woody plants
Brush Layering:
and cereal grains. These wattles provided
Brush layering is a technique much used in
slope stability until the interplantings were
Europe and to a limited extent in the United
established. The wattles also rooted and grew
States. Brush layering may be installed at the
if constructed of easily rooting species and
time of construction of new fills or in existing
installed at the proper time of year.
slopes by digging two to three foot or larger
The attached specifications and diagrams
“steps” sloping slightly in to the slope, placing
show a modification of the method in which
brush on the step and covering with soil. Butts
the brush is tied in bundles and overlapped.
are placed inward and the brush is criss-
This construction is somewhat more efficient,
crossed in a random fashion. The tips of the
but it is more difficult to get good soil
brush are left exposed to intercept and slow
water and detritus.
Wattling must be placed strictly on
Successive lifts are installed as needed.
contour on steep sites. On riparian sites subject
Criteria for vertical spacing is similar to that for
to stream or wave action wattling may be
wattling. In new fill, the brush may be as long
placed diagonally to wave action although
as is available. When placed at the right time
this technique has not been well researched.
of year the brush will root and grow.
The spacing of wattling will vary with
Brush layering is indicated for new fills,
the steepness and erodability of the site. On
shallow mass failures and repair of deep and/
very steep, highly erodible slopes a three
or narrow gullies.
foot vertical spacing might be required but
greater spacing has been used successfully on
Appendix ~ Brush Trenching:
Brush trenching is a useful technique for
Sequence of work should be in certain
intercepting shallow seeps and controlling
patterns. Scaling and site preparation should
piping, for spreading water in wetland
take place from the top of a slope and
construction or renovation, as energy
working down. Installation of structural and
dissipation along shorelines and as water
biogeotechnical work should proceed from
breaks on abandoned roads. A narrow trench
the bottom to the top and planting should
is dug, one to three feet deep, packed with
proceed from the top to the bottom.
a band of brush of the desired thickness and
the trench is backfilled. Height above ground
Tools: The tool required will depend upon the
may vary according to the needs.
revegetation plan, the size of the plants, soils,
Spacing of rows will vary with the need. In
wetland construction and renovation the rows
and size of the project and site conditions.
Chain saws, lopping and hand pruners and
may be spaced so that the vertical distance
hatchets may be needed for the preparation
between successive rows is as little as six
of cuttings and materials for wattling, brush
inches. Horizontal spacing will depend on the
layering, brush trenching and brush matting.
Heavy hammers and sledges are needed for
staking the job, driving stakes in the installations
Brush Matting:
of wattling and for installation of fencing and
This procedure is the laying of a mat of brush
cages for plant protection.
sufficiently thick to prevent scour along
Picks, mattocks and shovels are needed
streams, rivers and shorelines. The mat is
for site preparation, shovels and spades or tile
staked and wired to hold it in place and in
spades for trenching for wattling and brush
some instances it may be partially covered
layering, and dibbles or small hand picks for
with soil. The site must have a fairly flat profile
planting smaller plants and cuttings. Star drills
up and down slope but can follow the
and hammers may be needed for planting
meander of the shore in a horizontal direction.
unrooted cuttings in cemented soils. On some
The frequency of staking and method of
sites, power augers are useful for planting.
wiring, line wire or fencing wire will depend
Other materials may include fertilizers,
on the expected erosion forces. The toe of
fencing for plant protection, wire or fencing
the matting should be below the mean low
for installation of brush matting and stakes for
water level and should be anchored with logs,
layout and biogeotechnical work. Each job will
stones or rows of wattling.
have its own requirements.
Combination Treatments:
Planting: After site preparation and
The biogeotechnical methods can be used
biogeotechnical work is done, planting can
in any combination. Interplanting of cuttings
proceed. Plants, unrooted cuttings and brush
or transplants usually should be done. All work
for biogeotechnical construction are living
and combinations of work should be “tied”
things and must be handled accordingly.
together and to the surrounding stable areas.
They should be kept moist or well watered, as
“A chain is only as strong as its weakest link.”
cool as possible and protected until actually
Size of planting holes depends of the size
of the material to be planted and sometimes
on the soil conditions. When soils are friable
the holes may not need to be much larger
~ Appendix
than the plant root system. In heavy and
In revegetation projects it is usually
compacted soils, a larger hole to allow
desirable to set the plants just below the level
backfilling of looser material may allow better
at which they were and to cover the root
initial root penetration. The depth of the holes
systems with two or three inches of soil to
must be greater when fertilizers are to be used
act as a mulch. This is contrary to the usual
beneath the plant than when no fertilizer is
horticultural advice for planting in the irrigated
landscape. Backfill should be thoroughly
When fertilizers are used the hole should
tamped to insure good root soil contact
be deep enough to place the fertilizer in the
and to eliminate air pockets. If irrigation is
bottom of the hole, back fill with two or three
available, the plants should be watered
inches of soil, place the plant, cover the roots
in to aid this compaction and to supply
with one to two inches of native soil and
supplemental water.
still leave a depression around the plant to
The use of berms around the planting
collect water. Use only quantities of fertilizer
hole may be useful to concentrate rainfall
recommended by the manufacturer or as
or irrigation. Berms should be two to four
determined by soil or pot tests.
inches higher and of sufficient diameter to
Older recommendations often called for
perform this function. On sloping ground it is
amendments to be added to the backfill to
desirable to leave the berm open on the uphill
loosen the soil and increase water holding
side to trap more run-off. The inside of the
capacity. Research has shown that although
berm should be tapered toward the plant to
roots proliferate well in amended backfill,
concentrate water near the root system.
they do not penetrate the native soil as
well as they do when no amendment is
used. Amendments increase planting costs
Planting holes on slopes need special
attention. First, dig a “step” sloping into the
bank and then dig the hole at the back of this
step. Be careful to not loosen the front “lip”
of the step. Hole size and planting techniques
are for more level sites.
Planting should be done immediately
after digging the hole to reduce drying of
the backfill. This is especially important where
supplemental irrigation is not available. Plants
should be removed from the containers even
though they are “biodegradable”. The object
is to get the maximum contact between
the roots and the native soil. If the rim of a
“biodegradable” pot becomes exposed to
the air, the pot will act as a wick and create
a dry zone between the roots and the native
Any circling roots on the outside of the
root ball must be removed before planting.
Appendix ~ Biotechnical construction
Sample specifications
Contour wattling installation
season of vegetative dormancy, i.e. from the
time the resting buds are set and vegetative
growth has ceased in late summer until bud
break and the beginning of vegetative growth
Materials: Wattling bundles shall be prepared
in the late winter or spring. Where non-rooting
from live, shrubby stems of species which will
or dead brush is desired, preparation and
root such as willow, baccharis, dogwood, etc.
installation may be done any time of the year.
Where woody species are undesirable, e.g.
Bundles shall be prepared not more than
channels with restricted flow or where shading
two days in advance of installation except as
would restrict the growth of herbaceous
noted below. If provisions are made for storing
emergent or aquatic species, stems of non-
the bundles, submerged in water or sprinkled
rooting species or of dead material of species
often enough to be kept moist as well as
that would normally root shall be used.
covered, preparation may be up to seven (7)
days in advance of installation. Bundles may
Bundle Length: Wattling bundles may vary
be kept in suitable cold storage for up to three
in length depending on the length of the
(3) months. Such storage shall have humidity
species used. Bundles shall taper at the ends
control to avoid desiccation of the plant
and shall be one (1) to two (2) feet longer
than the average length of stems to achieve
this taper. Butts of stems shall not be more
Layout Staking: Location of rows of wattling
than one and one-half (1 ½) inch in diameter.
shall be staked, on contour, using an Abney or
similar type level. The stakes used in installation
Bundle Diameter: When compressed firmly
may be used for layout. Care must be
and tied, each bundle shall be eight (8)
exercised to maintain contour when traversing
inches in diameter. Maximum allowable
gullies to avoid diverting more water into these
variation is plus or minus two (2) inches.
Wattling Spacing: Vertical spacing of wattling
rows shall be as on the drawings. [Spacing
is a matter of judgment. It needs never be
closer than three (3) feet and may be as
much as twenty (20) feet vertical distance (not
slope face). Some factors affecting spacing
are length, steepness and stability of slope,
erodibility of the soil, expected precipitation
and run-off.]
Bundle Construction: Stems shall be
placed alternately and randomly so that
approximately one-half (1/2) the butt ends
are at each end of the bundle and the butts
are staggered within the bundle.
Time Preparation: The timing of preparation
of wattling bundles is vital when used with
the expectation of rooting. Preparation and
installation of wattling shall be during the
~ Appendix
Stakes: Stakes must be strong and long
Backfilling: Wattling shall be covered with site
enough to penetrate to the undisturbed
soils, filling voids within, behind and below the
substrate. The minimum sized stake shall be at
bundles and tamped thoroughly. Water may
least two by two (2x2) inches at the midpoint.
be used to aid in backfilling. Workers should be
Two by fours (2x4’s) cut on a diagonal are
encouraged to walk on the covered wattling
recommended. In rocky substrate, rebar or
as other work on the slope is done. Heavy
other metal stakes may be required. After
clay materials may need to be pulverized in
driving to a firm hold the rebar must be bent
order to attain suitable back filling. Successful
over the wattling to hold it in place. Live willow
rooting of the wattling will only be attained if
stems greater than one and one-half (1 ½)
the filling is done properly.
inch in diameter may be used for staking.
Progression of Work: Work shall progress from
Stake Spacing: Bundles shall be staked firmly in
the bottom to the top of the slope. On large
place with one row of stakes on the downhill
jobs, work might be underway on two or more
side of the wattling on not more than three (3)
rows of wattling at one time.
foot centers. A second row of stakes shall be
placed through the bundles at not more than
Prevention of drying: Exposure of the wattling to
five (5) foot centers. Where bundles overlap
sun and wind must be minimized throughout the
there shall be two stakes to “tie” the bundles
operation. Trenches shall be dug only as rapidly
together, one downhill and one through the
as placement and covering of the bundles is
ends of each bundle and between the last
accomplished to minimize the drying of the brush
two ties of each bundle.
and the soil removed from the trenches.
Installation: Bundles shall be laid in trenches
dug approximately one-half the bundle
diameter, immediately above the bottom row
of stakes. Ends of the bundles shall overlap at
least 12 inches. The last ties of each bundle
shall overlap sufficiently that a stake may
be driven between the last two ties of each
Appendix~ Brush Layering
Materials: Live brush of willow species shall be
used. When there is a shortage of willow, up to
Vertical Spacing: Vertical spacing shall be as
shown on the drawings.
50 percent of the brush may be of non-rooting
Trenching: Hand trenching shall start at the
species. When non-rooting species are used
bottom of the slope as in wattling placement.
they shall be mixed randomly with the rooting
Trenches shall be dug 24 to 36 inches in to the
slope, on contour, sloping downward from
Time of Work: Work shall be done during the
planting season specified for woody plant
species, i.e., fall and early spring.
the face of the bank 10 to 20 degrees below
New Fill: Brush layering in new fill shall be
placed on successive lifts of well compacted
Size of Brush: Length of brush shall vary
according to the particular installation and
shall be as shown on the Drawings. Hand
Placement: Brush shall be placed with butts
trenched brush layering used for small gully
inward and no less than 6 inches or more than
repair shall be from 2 to 3 feet long.
18 inches of the tips extending beyond the
fill face. Brush shall be 4 inches thick in hand
trenched placement work and 6 inches thick
in fill work. Thickness shall be measured after
compression by the fill or covering soil.
Covering: Brush layers shall be covered with
soil immediately following placement and the
soil compacted firmly. Covering may be done
by hand or with machinery.
Interplanting: Where required by the Drawings,
interplanting of woody plants (transplants and
/or unrooted willow cuttings) and grasses shall
follow placement of the brush layering.
~ Appendix
Brush matting channel protection
Brush Placement: Brush shall be placed butt
Materials: Live brush of willow, baccharis,
down in the trench, against the bank, and
dogwood or other species which will root
perpendicular to the base line. The layer of
shall be used. When species that will root
brush shall be placed to a thickness of two (2)
are in short supply substitution of other
to four (4) inches when compressed. See the
species for up to 50% of the material may be
drawings for the required thickness.
approved. Wattling for the anchor row will be
constructed and handled as noted in Contour
Anchoring: A single row of wattling, log or rock
Wattling Specifications. Stakes shall be as
of suitable size will be placed on top of the
described in the same specifications. Tie wire
butts and in the trench at/below low water
shall be single strand, galvanized, annealed
line. Wattling or logs will be properly anchored.
12 gauge wire such as fence wire, or various
See Wattling Specifications for preparation,
types of fencing as indicated in the drawings.
tying and anchoring wattling bundles.
Time of Work: Timing of work will be as
Staking and Tying: Construction stakes as
specified for contour wattling, i.e. the period
detailed in Wattling Specifications or other
of vegetative dormancy. When non-rooting or
approved staking shall be to a firm hold on
dead, rooting species are specified, work may
three (3) to four (4) foot centers, extending
be done at any time of the year.
beyond the matting on either side and one
(1) foot above the anchoring row to one (1)
Slope Preparation: The slope shall be free of
foot below the specified height of the mat.
debris and more or less a flat slope from top to
Stakes shall be of sufficient length to drive to
bottom but may be undulating in a horizontal
a firm hold and shall be driven to within four
plane within the area to be treated.
(4) inches of the top of the matting when
Trenching: A trench, eight (8) to twelve (12)
The brush matting shall be tied down with
inches deep shall be constructed just below
twelve (12) gauge galvanized, annealed line
the low water line and flush with (exterior to)
wire in horizontal runs and then diagonally
the plane of the slope face.
between each horizontal row of stakes. Ties to
the stakes shall be of such manner that if wire
breaks between two stakes the integrity of the
rest of the system will remain intact.
Appendix ~ Notes:
~ Appendix
Appendix E
Tree Removal and Tree Protection on Residential
and Commercial Properties at Lake Tahoe
By Jesse Jones, TRPA
forester. (See sample application, page E4.)
Trees provide many environmental values
The North Lake Tahoe Fire Protection District
to the Lake Tahoe ecosystem. They are not
also issues tree removal permits for defensible
only beautiful, but they provide strong root
space, and a similar program is being
systems that hold soil in place, preventing
developed in the Douglas County portion of
erosion. They are important sources of wildlife
the Basin. These permits are for removal of
and bird habitat. Even dead trees contain
unhealthy, crowded or hazardous trees. These
many insects that are valuable food sources
permits can be issued for trees on developed
for woodpeckers and other birds. Because
or undeveloped properties. When properties
of these resource values and the necessity
are in the process of being developed, tree
of restoring the Tahoe Basin ecosystem, the
removal permitting must be integrated with
cutting of trees is regulated.
other activities and permits on the site.
Resource managers want to prevent
The second kind of tree removal
needless removal of trees that are serving a
approval is that associated with permitted
valuable erosion control or other purpose.
development. When obtaining a permit to
On the other hand, when trees are over-
develop a property (build a building, grade
crowded, a severe fire hazard, or simply in the
and pave a parking lot, etc.), plans should
way of an approved project, there are ways
show all trees in the project area, and those
to get permission for removal. The following
trees which are to be removed should be
guidelines explain the specific details of the
designated with X’s. When the agency
permitting process.
reviewing the application approves the plans,
Tree removal at Lake Tahoe is regulated
this constitutes preliminary approval of the
by the TRPA, which defines tree removal
proposed tree removals, after the required
to include cutting, killing or damaging trees. pre-grading inspection. Trees should not be removed or damaged
Generally, the trees permitted for
without approval from TRPA or its partner
removal for development are those within the
agencies, including building departments
“footprint” of construction or within 6 feet of
in Washoe, El Dorado and Placer counties. new foundations. However, other trees may
Contractors should review plans and permits
be affected by construction and permitted for
before undertaking work that requires a
removal, such as trees affected by slope cuts
permit. Plans and permits are to be on site
or by utility excavations. It is best to identify all
during work. Please see the Table below on
of these tree issues as early as possible. Pre-
“Permits Required for Tree Removal From
grade inspection and subsequent inspections
Private Property.”
provide opportunities to discuss tree removals
with the official responsible for monitoring
Two Kinds of Tree Removal Approvals
compliance with permit conditions and
Tree removals are approved via two general
applicable regulations. paths. One is through applying for a Tree
Removal Permit, usually issued by TRPA’s
A project site may have trees outside the
construction footprint which are crowded,
Appendix ~ unhealthy or unsafe. Project proponents
following TRPA’s approved methods. Fencing
must apply for a Tree Removal Permit for these
beneath the dripline protects not only the
trees. Because different agencies, or different
trunk of the tree but also roots which feed
staff within the agencies, are involved in these
the tree. Many roots are located within a
two types of permitting, the applicant should
foot of the soil surface and are vulnerable to
provide information to involved permitting
the effects of soil compaction and change
agencies about all of the projects and
of grade. Vegetation protection fencing
activities being implemented together on the
is to be located at or beyond the dripline
site. The best time to obtain a Tree Removal
unless this zone overlaps the footprint of
Permit to address forest health and safety
permitted development. Where this occurs,
issues on a site is at the beginning of the site
additional root zone outside the development
development planning process.
footprint should be protected to reduce
stress to the tree. Replacing the fencing after
Temporary BMPs and Tree Protection
damaging the root zone does not mitigate
When implementing a project, it is important
the damage caused by failing to maintain
to avoid damage to trees which have not
protection. Damaging or killing trees not
been approved for removal. Vegetation
approved for removal by failing to implement
protection fencing and other vegetation
required tree protection is unauthorized tree
protection measures (temporary BMP’s)
removal. must be installed and maintained as shown
on plans or as approved by the inspector,
Chapter 4 of TRPA’s Code of Ordinances
exempts the removal of dead trees from tree
Permits Required for Tree Removal from Private Property
Proposed Activity or Project
TRPA Requirements
Removal of live trees smaller than 6” dbh1
No permit required unless tree is in a Stream
Environment Zone (SEZ) or it has been identified
as a tree to be planted or retained.
Removal of dead2 trees3
No permit required.
Removal of live trees 6” dbh or larger
Obtain a tree removal permit from TRPA or its
partner agencies.
Removal of more than 100 live trees 10” dbh Contact TRPA regarding additional permitting
or larger
Cutting, trimming or removal of live
Requires written approval from TRPA.
lakeshore or SEZ vegetation of any size
Tree removal for development of buildings,
Tree removal for development is reviewed
parking areas, etc.
through the permit application process.
dbh: Diameter at breast height, measured 4 1/2 feet above the ground on the uphill side of the
A dead tree is defined as a conifer totally lacking green limbs and needles throughout the crown, or
a deciduous tree determined to be dead by a qualified forester.
Removal of dead trees greater than 30” dbh outside urban areas or in SEZ’s requires TRPA approval.
In eastside forests (in Nevada and east of Carnelian Bay) the upper limit is 24” dbh.
SEZ vegetation: willows, cottonwoods, aspen, alder and other vegetation associated with areas of
wet soil conditions in early summer. Also lakeshore vegetaton and land capability “1b.”
~ Appendix
removal permitting requirements. However, if
And please, stop short of clearing your
trees are shown on approved project plans as
landscaping to bare dirt. Instead, maintain at
being alive and to be retained, their removal
least a thin vegetative, duff, or mulch layer to
from the project site may raise questions
prevent soil erosion. Chapter 5 of the Home
about whether they were dead or alive when
Landscaping Guide for Lake Tahoe gives a
removed and about the cause of death
good description of how defensible space
(failure to implement required protection
and best management practices can be
measures?). Contact the responsible
inspector prior to removing any tree, dead
Contact your local fire district regarding
or alive, which was shown on approved site
defensible space information and inspections.
plans as a live tree to be retained. When a
They can tell you what you need to do to
safety emergency exists, contact agencies
create defensible space, and they can guide
responsible for review as soon as possible. If
you to information on tree removal permitting.
you must remove a tree in an emergency,
The North Lake Tahoe Fire Protection District is
prepare documentation of the nature of the
the first fire district at Lake Tahoe to issue Tree
emergency and submit it as soon as possible
Removal Permits in conjunction with defensible
to the inspector in charge of the project.
space inspections.
Permanent BMPs, BMP Retrofit, and Tree Re-
How to obtain a permit
Tree Removal Permit applications can be
Installment of permanent BMP’s may involve
obtained at the TRPA office, from the TRPA
excavation which can damage or remove
website, or by leaving your address or fax at
tree roots. BMP design should minimize
(775) 588-4547 x 310. The cost for submitting
potential for damage to trees. When installing
the application is $53 for a lot under 5 acres
permanent BMP’s such as dripline trenches
and more for larger acreages. The “Sample”
or infiltration wells, contractors should make
Tree Removal Permit in this Appendix is helpful
reasonable efforts to avoid damaging or
in learning about the process beforehand.
removing tree roots, especially tree roots
The TRPA website and the application
larger than 4” in diameter. Often, minor
contain additional information on tree
adjustments can result in avoidance of
removal. Submitting a completed application
impacts while maintaining BMP function. If you
is usually the fastest way to get the forester to
think installing a BMP will destabilize a tree,
your site. Due to the large volume of tree
contact the project inspector or TRPA prior to
removal permit applications in the Lake Tahoe
inflicting such damage. Region, applications take an average of two
A Word about Defensible Space
weeks to process and are generally processed
in the order received. If you have questions,
TRPA strongly encourages homeowners to
you can contact TRPA’s forester, Jesse Jones,
maintain a defensible space around their
Tahoe Regional Planning Agency, 128 Market
structures. TRPA also encourages you to
Street, P.O. Box 5310, Stateline, NV 89449,
maintain as much native vegetation as you
(775) 588-4547 ext. 266.
can while incorporating defensible space
zones and ladder fuel management around
your home.
Appendix ~ (SAMPLE)
Note: This form shall not be formatted or revised except by TRPA staff.
Payment of $53 filing fee required at time of application.
We accept check, cash, and money orders only. Make checks payable to TRPA or Tahoe Regional Planning Agency.
* - required information OWNER(S) OF RECORD:
*Mailing address:
E-Mail Address:
BE SENT: (If person other than property owner, authorization portion on page 4 must be completed.)
Mailing address:
*Assessor’s Parcel Number (APN):
*Street address:
Lot #:
*Do you have an application under review or an active permit for any development activity on this site,
including building, grading or paving?:_______________________________________________________
Tree removal from the footprint of permitted “development” (new coverage, grading, paving, construction, etc.) is
reviewed and permitted through the applicable permitting processes for these activities. Please get necessary
approvals from reviewing agencies for these tree removals. The tree removal permit application is to remove
trees that are crowded, unhealthy or hazardous to life or property, not for development permitting.
The application fee may be waived if the applicant submits, with this application, a letter or form from the local fire
district documenting that fire district staff have inspected the property and determined that tree removal is needed
to provide for adequate defensible space. The date on the letter cannot be over one year old. If the letter is not
enclosed with the application at the time of application, you will not qualify for a waiver. Applications with a waiver
will be marked for defensible space only. If you wish to have trees marked for any other reason, you will need to
submit an application fee.
a. Removal of trees smaller than 6” dbh (diameter at breast height, 4 ½ feet from the ground) from
areas which are not in Stream Environment Zones or backshore areas DOES NOT REQUIRE A
PERMIT. However, trees of any size which were planted or required to be retained as part of a
permit cannot be removed without TRPA approval.
Please Return to: TRPA, Attn: Tree Permits, P O Box 5310, 128 Market St., Stateline, NV 89449
Applications must be either mailed or dropped off. They cannot be faxed. Editions older than 3/1/05 not valid.
~ Appendix
Page 1 of 4
Revised May 11, 2005
b. The manipulation of live vegetation in Stream Environment Zones and backshore areas, including
cutting live trees, shrubbery or herbaceous vegetation of any size, or planting or landscaping in
Stream Environment Zones and backshore areas, requires TRPA review. Please specify request
for review of such activity. You may remove dead materials from these areas, but heavy equipment use,
which can damage soils, requires TRPA approval.
c. Removal of dead trees from residential and commercial properties requires no permit. A dead
tree is one totally lacking in green leaves/needles and shoots. However, TRPA’s Old Growth forest
protection ordinances require the review of removal of large dead trees (snags) from Stream Environment
Zones (streamside, wet area, lakeshore). In Nevada and on the north shore east of Carnelian Bay, the
applicable size requiring review is larger than 24” dbh. In the rest of California the size requiring review is
larger than 30”. Call (775) 588-4547 x 266 for a review. Do not apply for a permit.
d. Tree topping, removing live limbs from the upper 2/3 of the height of a tree, and other activities,
which may harm trees, such as trenching through roots, requires TRPA approval.
e. TRPA approves, without review/permit, trimming of limbs necessary to maintain 10 feet of
chimney outlet clearance and up to 10 feet of clearance for buildings and decks, trimming of
branches over driveways to a height of 15’ for fire truck access, as well as trimming to maintain
clearance for regular use of permitted driveways and permitted walkways. Trimming shall not
exceed that necessary to accomplish these safety objectives.
f. TRPA approves, without review/permit limb pruning necessary to prevent limbs from contacting
covered residential 220 volt electrical service lines, cable and phone lines on YOUR property
provided that limbing is restricted to that necessary to achieve this objective while adhering to
sound pruning practices. Federal safety regulations prohibit non-certified persons from working within
10 feet of high voltage power lines (“street” lines). Contact your local Sierra Pacific Power Company
office if you have concerns about these power lines. The Sierra Pacific Power Company DOES NOT
maintain clearance of cable and phone lines.
g. A Tree Removal Permit does not authorize the use of heavy equipment in tree removal. Heavy
equipment use in tree removal must conform to Chapter 71 of the Code of Ordinances for the Lake Tahoe
Region, which includes restrictions on heavy equipment use on steep slopes and in Stream Environment
h. Stump excavation is not part of this permit.
Provide a description of the trees or property to be reviewed for tree removal permitting in the space provided
on the next page. You may request that all trees be reviewed on a parcel if you provide detailed information
regarding parcel boundaries. We cannot permit tree removal on a parcel other than your own. Trees near illdefined property boundaries may not be able to be marked. For removal of specific trees, describe them below;
for example, “cedar tree in front deck with ribbon tied around it,” or, “the fir tree with dead top near the right rear
corner of house.” Proposed tree removals will be reviewed consistent with TRPA tree removal guidelines found in
section 71.5 of the TRPA Code of Ordinances.
Please provide the reason for removal. (For example: diseased, dead, crowded, safety hazard)
Please provide information on property access information (i.e. gated, dogs).
If the tree(s) in question are on a property line, you must obtain written permission from the other property
owner(s). The written permission must state the owner(s) name(s), the property address in question and have
their signature(s).
Please Return to: TRPA, Attn: Tree Permits, P O Box 5310, 128 Market St., Stateline, NV 89449
Applications must be either mailed or dropped off. They cannot be faxed. Editions older than 3/1/05 not valid.
Page 2 of 4
Revised May 11, 2005
Appendix ~ (SAMPLE)
Description of tree removal request, including reasons for removal:
If you need more room for the description or sketches, use additional sheets of paper.
Application continued on next page, signature(s) required!
Please Return to: TRPA, Attn: Tree Permits, P O Box 5310, 128 Market St., Stateline, NV 89449
Applications must be either mailed or dropped off. They cannot be faxed. Editions older than 3/1/05 not valid.
~ Appendix
Page 3 of 4
Revised May 11, 2005
I hereby authorize TRPA to access the property for the purpose of site visits. I hereby declare under penalty of
perjury that this application and all information submitted as part of this application are true and accurate to the
best of my knowledge. I am the owner of the subject property or I have been authorized in writing by the owner(s)
of the subject property to represent this application and understand that should any information or representation
be submitted in connection with this application be incorrect or untrue, TRPA may rescind any approval or take
other appropriate action. I further understand that additional information may be required by TRPA to review this
Signature: (Original Signature required.)
*________________________________________ *At_______________________ *On___________________
Person Preparing Application
The following person(s) own the subject property (Assessor’s Parcel Number____________________________)
or have sufficient interest therein to make application to TRPA:
Print Owner(s) Names(s):
I/We authorize __________________________________________________________________ to act as my/
our representative in connection with this application to TRPA for the subject property and agree to be bound by
said representative. I/We understand that additional information may be required by TRPA beyond that submitted
by my/our representative, to review this project. Any cancellation of this authorization shall not be effective until
receipt of written notification of same by TRPA. I also understand that should any information or representation
submitted in connection with this application be incorrect or untrue, TRPA may rescind any approval or take
other appropriate action. I/We further accept that if this project is approved, I/we, as the permittee, will be held
responsible for any and all permit conditions.
Owner(s) Signature(s) (Faxed signatures acceptable.):
The only signature accepted for an HOA is the Board President/Chairman.
The only signature accepted for a corporation/company is the CEO/President/Chairman of the Board.
___________________________________________________________ Date:__________________________
___________________________________________________________ Date:__________________________
Date Received:______________________________________ By:____________________________________
Filing Fee Paid:______________________________________ Receipt Number:_________________________
Please Return to: TRPA, Attn: Tree Permits, P O Box 5310, 128 Market St., Stateline, NV 89449
Applications must be either mailed or dropped off. They cannot be faxed. Editions older than 3/1/05 not valid.
Page 4 of 4
Revised May 11, 2005
Appendix ~ Notes:
~ Apppendix
Appendix F
Invasive Weeds in the Lake Tahoe Basin
nvasive weeds are plants that have been
introduced into an environment outside of
Do’s and don’ts of weed control
their native range, where they have few
is correctly identified. Don’t be afraid to
or no natural enemies to limit their spread.
Invasive weeds affect us all — as contractors,
Take no action until you’re sure the weed
ask for help.
Avoid continually disturbing soil, or leaving
homeowners, taxpayers, consumers, tourists,
expanses of bare soil. These actions
and land managers. Invasive weeds:
encourage weed infestation. Clear only
Cost you money for control
Decrease property values
Ruin trails and parks
Increase fire danger
Destroy wildlife habitat
Reduce opportunities for hunting, fishing,
the area necessary for your project.
topsoil come from weed-free locations. If
necessary, inspect the source.
Damage water quality
Ruin your view — and your enjoyment of
control weed infestations early.
are not on the attached list of “Weeds of
Concern,” such as Scotch broom.
Τhreaten naturally occuring plant species
How it happens
Weeds are spread in many ways. Any time
people or their animals work or play in areas
infested by invasive weeds, there is a chance
they will move the infestation to a new area.
When a vehicle is driven through a weedinfested area, weed seeds may become
lodged between the tire treads, in the coils of
a winch, behind the license plate, or in cracks
and crevices on the underside of the vehicle.
Seeds may travel hundreds of miles before
becoming dislodged in an area where weeds
were not previously found. The source of many
infestations has been traced to roads, trails,
railroads and other transportation corridors.
Weeds are also spread during construction
and maintenance activities, when contaminated fill, gravel, topsoil and other products
are moved from an infested site to your neigh-
Μake sure the plants you buy from
nurseries for planting around your home
your neighborhood
After earth-moving construction projects,
monitor the site carefully to find and
camping, and other recreational activities
Make sure any shipments of gravel, fill, or
Do not dump aquatic plants from an
aquarium into local waters or flush them
down a toilet.
Weeds of concern in the
Tahoe basin
1. Musk thistle (Carduus nutans)
2. Scotch thistle (Onopordum acanthium)
3. Canada thistle (Cirsium arvense)
4. Russian knapweed (Acroptilon repens)
5. Diffuse knapweed (Centaurea diffusa)
6. Squarrose knapweed (Centaurea
7. Yellow starthistle (Centaurea solstitialis)
8. Purple starthistle (Centaurea calcitrapa)
9. Scotch broom (Cytisus scoparius)
10. Hoary cress (Cardaria draba)
11. Sulfur cinquefoil (Potentilla recta)
12. Klamathweed (Hypericum perforatum)
13. Teasel (Dipsacus fullonum)
Appendix ~ 14. Curlyleaf pondweed (Potamogeton
invasive weeds, please see the University of
15. Bull thistle (Cirsium vulgare)
Nevada Cooperative Extension publication,
16. Eurasian watermilfoil (Myriophyllum
“Invasive Weeds of the Tahoe Basin,” SP-04-20,
17. Perennial pepperweed or Tall whitetop
(Lepidium latifolium)
18. Spotted knapweed (Centaurea
19. Dalmatian toadflax (Linaria genistifolia
spp. dalmatica)
20. Yellow toadflax (Linaria vulgaris)
21. Oxeye daisy (Chrysanthemum
~ Appendix
For additional details and photos of these
or call Sue Donaldson, UNCE, 775-784-4848.
Bringing the University to You
Fact Sheet FS-03-59
Measures to Prevent the Spread of Noxious and Invasive
Weeds During Construction Activities
Steven Siegel, Environmental Scientist
Sierra Pacific Power Company
Susan Donaldson, Water Quality Education Specialist
University of Nevada Cooperative Extension
nvasive weeds are plants that have been introduced into an environment outside of their
native range, where they have few or no natural enemies to limit their spread. Invasive
weeds affect us all–as homeowners, taxpayers, consumers, tourists, and land managers.
Some invasive weeds are designated as noxious in Nevada state law, requiring control by the
property owner or manager.
The spread of invasive and noxious weeds is a significant issue in construction projects that
involve land disturbance. Earth moving activities contribute to the spread of weeds, as does the
use of contaminated construction fill, seed, or erosion-control products. Permits for construction
projects may now require that measures be incorporated to identify and manage these weeds.
Experience has demonstrated that prevention is the least expensive and most effective way
to halt the spread of noxious and invasive weeds. Preventing the establishment or spread of
weeds relies upon:
Educating workers about the importance of managing weeds on an ongoing basis;
Properly identifying weed species;
Avoiding or treating existing weed populations; and
Incorporating measures into projects that prevent weed seeds or other plant parts from
establishing new or bigger populations such as certification of weed-free products.
A search was conducted of Internet sites and published permit requirements that
incorporate weed prevention measures to determine appropriate practices to prevent weed
spread during projects involving land disturbance. These measures may not be applicable or
appropriate for all projects, but the list below should contain at least a few useful measures for
any project. The weed management process should include education, weed identification,
avoidance or treatment and reclamation of bare or disturbed areas. Following the list of
management practices, we have provided sample suggested language for inclusion in
contracts for projects that may be impacted by weed invasion.
Appendix ~ Construction and Property Maintenance
Incorporate a strategy of integrated weed management into construction layout,
design, and project alternatives evaluation.
Remove or treat seed sources and other viable reproducing plant parts that could be
spread by construction disturbance or by passing vehicles or foot traffic.
Avoid moving weed-infested gravel, rock and other fill materials to relatively weed-free
locations. Gravel and fill should come from weed-free sources. Inspect gravel pits and
fill sources to identify weed-free sources.
Identify existing noxious weeds along access roads and control them before
construction equipment moves into a relatively weed-free areas.
Clean off-road equipment (power or high-pressure cleaning) of all mud, dirt, and plant
parts before moving into relatively weed-free areas.
Minimize the removal of roadside vegetation during construction, maintenance and
other ground-disturbing activities.
Use only certified weed-free straw and mulch for erosion control projects. Consider the
use of weed-free fiber roll barriers or sediment logs.
Minimize contact with roadside sources of weed seed that could be transported to
other areas.
Keep active road construction sites that are in relatively weed-free areas closed to
vehicles that are not involved with construction.
10. Road maintenance programs should include monitoring and treatment for noxious
11. Provide training to management and workers on the identification of noxious weeds,
the importance of noxious weed control and measures to minimize their spread.
12. Quickly treat individual plants or small infestations before they become established,
produce seed or are able to spread.
Seeding and Planting
Obtain soil components and mulches from weed-free sources.
Purchase and use only certified weed-free seed.
Reestablish vegetation on all bare ground (including areas denuded by fire) to minimize
weed spread.
Ensure establishment and maintenance of vigorous, desirable vegetation to discourage
Minimize contact with sources of weed seed in areas not yet revegetated.
Monitor all seeded sites for weed infestation. Treat all weeds adjacent to newly seeded
areas prior to planting and treat planted areas for weeds in the first growing season.
Mulch to minimize the amount of noxious weed seeds that will reach the soil surface
and subsequently germinate.
Grazing and Livestock Management
Refrain from grazing or moving cattle through populations of noxious weeds while they
are setting seed or when fruit is ripened.
~ Appendix
Purchase only weed-free hay and other feed.
Keep cattle and other livestock out of newly planted areas.
Employ rotational grazing and other management strategies that minimize soil
Purge animals with weed-free feed for five days before moving them from infested to
non-infested areas
1. Identify and map noxious weed populations on lands that you own or manage. Provide
mapping information using the protocol for your state’s weed mapping efforts. Contact
the Natural Resources Conservation Service, 775-784-5863 ext. 118, for Nevada’s
Suppress fires that may impact native plant populations. Clean vehicles that may
contribute to the spread of weeds during fire fighting activities.
Minimize soil disturbances caused by water, vehicle, and animal traffic in weed infested
Minimize transport of weed seeds or reproductive weed parts by irrigation water.
Suggested Construction Contract Wording for Weed Prevention
Note: This section is provided as an example of language that can be included in
construction contracts when appropriate to help prevent the spread of weeds. Nevada
Revised Statutes Chapter 555 advises that the control of noxious weeds is the responsibility of
every landowner or occupant. This suggested contract wording can be modified as needed to
fit individual projects.
Prior to any construction disturbance you will:
Identify and map all noxious and invasive weed populations present in the project area
Treat or contain any weed populations that may be impacted or disturbed by
construction activity
Flag all weed populations to be avoided
Provide training to construction workers and equipment operators on the identification
of weeds to be avoided
Certify that all construction material sources used for supplies of sand, gravel, rock and
mulch are weed-free prior to obtaining or transporting any material from them
Obtain and use only certified weed-free straw or use fiber roll logs for sediment
Wash and inspect all vehicles for weed seeds and plant parts prior to bringing them
onto the job site
Install stormwater Best Management Practices to prevent erosion of the job site and the
potential transport of weedy material onto or off of the job site
During construction you will:
Minimize ground disturbance and vegetation removal as much as possible and
Wash, or using an air compressor, blow clean all vehicles (including tires and
undercarriage) that may have entered weed-infested areas prior to entering uninfested
areas of the job site
Appendix ~ •
Restrict vehicles or other traffic that may transport weed seeds or plant material from
entering the job site unless they are first washed and inspected
After construction is complete you or the property owner will:
Revegetate or otherwise prevent the establishment of weeds in all areas of the job site
through a program of monitoring and post-construction weed treatment for the life of
the project
Revegetate using soil components and mulches obtained from non-weed infested
Utilize seed and other plant materials that has been checked and certified as noxious
weed-free and that has a weed content of 0.05 percent or less
Revegetate using plant materials that have a high likelihood of survival
Maintain all planted material and native vegetation located on the project site for the
life of the project
California Bureau of Land Management. 2003. Weed Management and Prevention Guidelines for Public
Center for Invasive Plant Management. 2003. Guidelines for Coordinated Weed Management of Noxious
Weeds: Development of Weed Management Areas, Section IV: Prevention and Early Detection
and Appendix 1: Sample Contracts, Agreements and Memorandums of Understanding. http://
Colorado Bureau of Land Management. 1991. Prototype Weed Prevention Measures. http://
Lewis County Noxious Weed Control Board. 2003. Weed Prevention. Washington State University
Cooperative Extension. Lewis County, Washington.
Sheley, Roger and Kim Goodwin. 2000. Plan Now For Noxious Weed Invasion. Montana State University.
Sheley, R., M. Manoukian and G. Marks. 2000. Preventing Noxious Weed Invasion. Pp. 69-72 in: Biology and
Management of Noxious Rangeland Weeds, ed. R.L. Sheley and J.K. Petroff. Oregon State University
Press, Corvalis, Oregon.
Trainor, Meghan and A.J. Bussan. 2000. Integrated Weed Management; Preventing Weed Invasion.
Montana State University Extension.
For more information, contact:
University of Nevada Cooperative Extension
PO Box 11130, Reno, NV 89520
(775) 784-4848
Nevada Department of Agriculture
350 Capitol Hill, Reno, NV 89502
(775) 688-1180 Ext. 269
The University of Nevada, Reno is an Equal Opportunity/ Affirmative Action employer and does not
discriminate on the basis of race, color, religion, sex, age, creed, national origin, veteran status, physical
or mental disability, or sexual orientation in any program or activity it conducts. The University of Nevada
employs only United States citizens and aliens lawfully authorized to work in the United States.
~ Appendix
Appendix G: Supplemental BMPs for an Integrated Landscape
BMPs include installing permanent conservation practices such as infiltration devices and paved
driveways, but did you know that BMPs also include practicing low impact, environmentally
sensitive management on your property? I’d like to ask you a few questions and see if we can
provide additional assistance regarding other types of BMPs that will help save Lake Tahoe’s
Landscape Maintenance: Do you consider your landscape high maintenance (greater
than 15 hours/month), medium maintenance (6-15 hours/month), low maintenance (2-6
hours/month) or ultra-low maintenance (0-2 hours/month)? Do you have native vegetation
or natural areas in your landscape?
Did you know that landscapes with lower maintenance requirements are actually
better for the health of the Lake? Low maintenance landscapes tend to have more
native vegetation and natural areas that need less water and fertilization than higher
maintenance landscapes. Less water and fertilizer means less runoff and nutrients that
wash into Lake Tahoe. Native plants are suited to the mountain environment and do not
require fertilizer or watering once the plants are established. There is a list of native and
adapted plants (including descriptions and pictures) in the Home Landscaping Guide in
Chapter 7. (See also pages 12-13 in the Home Landscaping Guide.)
Fertilizer: Do you fertilize your lawn or garden? What type of fertilizer do you use?
Proper fertilization is very important to the health of the lake because the nutrients that
feed your plants can wash off the soil’s surface or leach through the groundwater and
feed algae growth in the Lake. Proper fertilization practices include 1) using the correct
amount, 2) applying only in the spring and late summer, and 3) avoiding application near
streams or shore-zone areas. We also suggest using slow release fertilizers and checking
the weather to be certain that a rain event is not expected in the forecast. (See pages 116
- 118 in Home Landscaping Guide.)
Water Conservation: Did you know that irrigation accounts for up to 50% of a municipality’s
A well-planned irrigation system is important to prevent inefficient watering, runoff and
water demand? What kind of irrigation system do you use?
erosion. Many Tahoe soils can only infiltrate about a quarter inch of water an hour before
it starts to run off the surface. Water demands increase in the summer months due to
irrigation use. Most landscapes in Tahoe require only a total of an inch and a half to two
inches of water a week during the hot dry days of summer. Plant water requirements
are lower in early spring and fall, as plants can still access water from snowmelt or are
beginning to go dormant. During these times, you can reduce irrigation schedules by
almost half. Watering your landscape during a rain event wastes water and contributes
additional runoff to Lake Tahoe. Contact a member of the BMP Retrofit Partners to
schedule an outdoor irrigation audit on your property. Incline Village residents can call
(775) 831-8603.
Appendix ~ □
Storm Drains: Did you know that our storm drain system goes directly into the Lake?
We need to remind our neighbors of the importance of keeping pollutants out of our storm
drains—things like motor oil, antifreeze, trash, dirt, paints, dog and cat manure, herbicides
and pesticides. When it rains, the residues from herbicides and pesticides will wash into the
streets, storm drains, streams, and into Lake Tahoe. Don’t dump these harmful chemicals
down your drain or in the storm drain! If you wash your car at home, consider washing it on
areas covered in pine needles or sturdy turf, but not on bare soil areas. Contact your local
refuse collection area for more information on how to safely and properly dispose of these
chemicals. Look for “earth-friendly” products to use in and around your home instead. In
Incline Village and Crystal Bay, call WASTE NOT at (775) 831-8603; in Kings Beach, Tahoe
City and Truckee, call Tahoe Truckee Sierra Disposal at (530) 583-0148 and for South and
West shores of Lake Tahoe call South Tahoe Refuse Company at (530) 541-5105.
Recycling: Do you recycle? Did you know that recycling is only part of the “loop”?
When you recycle you provide new materials at a cheaper cost to manufacturers to
produce new products from post consumer materials like metal, paper and cardboard.
But, the concept of recycling only works if there are consumers willing to buy those
products made from recycled content material. “Close the Loop” by purchasing items
made from at minimum 30% post consumer wastes. Reuse all things you can: clothes,
cars, tires, glass jars, plastic ware, shopping bags etc… all the products that have been
developed for disposability should be avoided or reused. In Incline Village and Crystal
Bay, call WASTE NOT at (775) 831-8603; in Kings Beach, Tahoe City and Truckee, call Tahoe
Truckee Sierra Disposal at (530) 583-0148 and for South and West shores of Lake Tahoe call
South Tahoe Refuse Company at (530) 541-5105.
Animals: Has a bear ever gotten into your or your neighbor’s trash?
We live on the edge of a vast, largely undisturbed forest. Many animals call this place
home, and have long before we arrived to claim our Mountain dream home. It is
important to be diligent when setting out trash. Double bag meats, cheese and other
smelly items. At minimum, don’t set your trash out until the morning. Optimally, all residents
in the animal/human interface will acquire a bear resistant trash container. These can
prevent the needless execution and/or displacement of our furry neighbors by eliminating
the temptation of access to our trash.
Defensible Space: Have you evaluated your residence for defensible space in the event
of wildfire?
Defensible space practices are recommended throughout the Tahoe Basin and the Sierra.
Proper attention to the principles of Defensible space will reduce your fire hazard without
increasing erosion potential on your property. It is recommended that property owners
consider their defensible space needs as a part of their planning to implement required
BMPs for water quality. There is a detailed discussion of defensible space practices in
Chapter 5 of the Home Landscaping Guide for Lake Tahoe.
~ Appendix
The BMP Retrofit Partners
Who are we and what do we do?
The Contractors Workshop is organized and
For Residential properties in California:
sponsored by the following partner agencies who
Tahoe Resource Conservation District
are tasked with implementing BMPs on private
Backyard Conservation Program
property in the Lake Tahoe Basin through their
870 Emerald Bay Road, Suite 108
respective programs:
South Lake Tahoe, CA 96150
Natural Resources Conservation Service (NRCS)
Phone: (530) 543-1501, Ext. 6
(530) 543-1660
e-mail: [email protected]
Tahoe Regional Planning Agency (TRPA)
For Residential properties in Nevada:
Nevada Tahoe Conservation District
Backyard Conservation Program
University of Nevada Cooperative Extension (UNCE)
Bringing the University to You
P.O. Box 4605, 297 Kingsbury Grade, Suite G, Stateline, NV 89449
Hotline: (775) 586-1610, Ext. 28
(775) 586-1612
e-mail: [email protected]
Tahoe Resource Conservation District (TRCD)
For Commercial & Multi-Family properties in Nevada and California:
Tahoe Regional Planning Agency
Nevada Tahoe Conservation District (NTCD)
Erosion Control Team
P.O. Box 5310
128 Market Street
Stateline, NV 89449-5310
Phone: (775) 588-4547, Ext. 202
(775) 588-4527
e-mail: [email protected]
Education/Outreach Training:
University of Nevada Cooperative Extension
P.O. Box 8208,
865 Tahoe Blvd., Suite 110
Incline Village, NV 89452-8208
Phone: (775) 832-4150, Ext. 102
(775) 832-4139
e-mail: [email protected]
Manual design by The Write Type, through the generous funding
of Cooperative State Research, Education and Extension Service
Photo courtesy of J.T. Ravizé 