BLD2023-0401+SWPPP+3.31.2023_5.27.17_PM+3457681RECEIVED
Apr 13 2023
Construction Stormwater Pollution Prevention Plan (CSWPPP)
Short Form for Small Construction Projects
BLD2023-0401
Background Information
Property Owner: Bernard Shen and Catherine Federman
Contact Person: contact civil engineer on behalf of owner reg: stormwater/TESC--Duffy Ellis
(If different from the owner, all questions and correspondence will be directed to the individual listed as
contact person.)
Address of Contact Person: 102 NW Canal Street, Seattle, WA 98107
Phone Number: 206-930.0342
Project Title: Shen/Federman Residence
Site Address: 23310 Humber Lane, Edmonds, WA 98020
Parcel Number: 0057130001000
Give an accurate, brief description of the proposed project's scope and nature:
1. General description:
A new single family house proposed on this lot. Demo of existing house necessary. Architect is Patricia Brennan Architects.
Scope of disturbance includes demo and remove existing single -story house and driveway; construct new house + basement as
depicted on building permit set. See sheet C1.0 for our basic erosion & sediment control plan including typical silt fence, tree
protection, and limits of disturbance shown.
2. Area of site (square feet or acres): 12,600 sf
3. Proposed area of land disturbance (square feet or acres): 13,000 sf
4. Proposed quantity of excavation (cubic yards): 25
5. Proposed quantity of fill (cubic yards): 25
6. Square footage of buildings to be constructed: roughly 2,500 sf building footprint
7. Description of adjacent areas which may be affected by site disturbance (i.e. streams, lakes, wetlands,
residential areas, roads)
Mainly on -site disturbance plus some disturbance in street necessary to install utility connections.
8. Description of critical areas that are on or adjacent to the site.
None exist to our knowledge
9. Describe potential erosion problems on site.
We don't foresee this a difficult site to control sediment runoff.
Required Elements - Construction Stormwater Pollution Prevention Plan
Indicate the BMPs to be used for each element. If site conditions render an element unnecessary, check
"other" and describe why it is not needed.
1. Mark Clearing Limits
❑ Preserving Natural Vegetation— BMP C101
❑✓ High Visibility Fence — BMP C103
❑,/ Tree Protection during Construction — BMP T101
Other
2. Establish Construction Access
✓❑ Stabilized Construction Entrance/Exit — BMP C105
❑ Wheel Wash — BMP C106
❑ Construction Road/Parking Area Stabilization — BMP C107
❑✓ Other Use existing driveway whenever possible
3. Control Flow Rates
❑ Sediment Trap — BMP C240
❑✓ Other
4. Install Sediment Controls
❑ Vegetated Strip— BMP C234
❑✓ Silt Fence— BMP C233
❑✓ Wattles — BMP C235
❑ Other
5. Stabilize Soils
✓❑
Mulching — BMP C121
❑
Plastic Covering — BMP C123
❑
Topsoiling/Composting — BMP C125
❑
Sodding— BMP C124
❑✓
Nets & Blankets — BMP C122
❑
Temporary & Permanent Seeding — BMP C120
❑
Other
6. Protect Slopes
❑✓ Temporary & Permanent Seeding — BMP C120
❑ Plastic Covering — BMP C123
❑ Interceptor Dike and Swale — BMP C200
❑✓ Nets & Blankets — BMP C122
❑ Other
7. Protect Drain Inlets
❑✓ Storm Drain Inlet Protection — BMP C220
❑ Other
8. Stabilize Channels and Outlets
❑ Channel Lining— BMP C202
❑ Outlet Protection — BMP C209
❑,/ Other Not warranted.
9. Control Pollutants
❑✓ Concrete Handling— BMP C151
❑ Sawcutting and Surfacing Pollution Prevention — C152
✓❑ Material Delivery, Storage and Containment —C153
❑ Other
10. Control De -Watering
❑✓ Level Spreader— BMP C206 Infiltration (Provide details)
❑ Discharge to sanitary sewer (METRO and Bellevue Utilities permits required)
❑ Other
11. Maintain BMPs
❑,/ Maintain and repair in accordance with BMP specifications
❑ Other
12. Manage the Project
• Phase construction — describe
Install erosion controls, demo house, excavate for foundation forms, install underground utilities as needed around house, backfill.
Begin stick frame construction.
• Limit work to the dry season
Summer to early fall is ideal time period for this work. If during rainy season, contractor will need to better control runoff so sediment
does not enter storm system or neighboring yard.
• Inspect and monitor all BMPs
Keep stockpiles protected with temp plastic covering during rainy season. Keep Silt Fence upright and pinned. Check and adjust
straw waddles after storm events on daily basis if warranted. Just keep dirty water from leaving site.
• Other
• Pollution prevention contact list — Contact list must be attached to this CSWPPP and maintained at
the job site
• Reporting and recordkeeping — Site inspection forms must be attached to this CSWPPP and
maintained at the job site
13. Protect Low Impact Development BMPs
❑ Buffer Zones — BMP C102
❑✓ High Visibility Fence — BMP C103
❑ Silt Fence — BMP C233
❑ Vegetated Strip — BMP C234
❑ Other
See next page for additional instructions.
BMP Details
Attach to the CSWPPP narrative a copy of each BMP detail/specification that is called out on the narrative. The
BMP standard details can be downloaded from: http://www.bellevuewa.gov/clearing-grading-standards.htm.
ESC (Erosion and Sediment Control) Plan
Attach an ESC plan (minimum 11" x 17") that includes the following:
a. Legal description of subject property.
b. North Arrow see civil drawing C1.0 submitted with building permit
C. Property boundaries
d. Boundaries of existing vegetation, e.g. tree lines, pasture areas, etc.
e. Identify and label areas of potential erosion problems.
f. Identify any on -site or adjacent surface waters, critical areas and associated buffers.
g. Identify FEMA base flood boundaries and Shoreline Management boundaries (if applicable)
h. Show existing and proposed contours.
i. Delineate areas that are to be cleared and graded.
j. Indicate location of BMPs and other required CSWPPP elements.
k. Name and phone number of person(s) responsible for preparation and maintenance of the CSWPPP.
NOTE: The ESC plan can be included on the project site plan, provided the plan remains legible.
GENERAL CONTRACTOR TO FILL OUT PRIOR TO CONSTRUCTION
CONSTRUCTION EMERGENCY CONTACT SHEET
Date
Project Name: Shen/Federman Residence
Project Address: 23310 Humber Lane, Edmonds, WA 98020
Type of Work: single-family residential
Developer: owners
Contact: Office: 24-hr:
General Contractor: DHL Inc.
Contact: Jason Holub Office: (425) 888-1853 24-hr:
Utilities Sub -Contractor: TBA
President/Owner:
Office: Home: 24-hr:
Project Manager: TBA
Office: Home: 24-hr:
Superintendent: TBA
Office: Home: 24-hr:
Foreman: TBA
Office: Home: 24-hr:
Erosion Control Lead: TBA
Office:
Home: 24-hr:
Rev. Jan. 2017
City of
Bellevue
FABF<
44 �-'Rdeo= Tree Protection Requirements
Clearing & Grading
Development Standards
BMP T101: Tree Protection Requirements
Purpose The section identifies management practices to employ at construction sites to
guarantee successful tree and vegetation protection before, during, and through a
lifetime of site use and maintenance. The City of Bellevue regulates and
manages tree retention during development through the Land Use Code and the
Clearing and Grading Code. Trees and vegetation are preserved for several
reasons:
■ To sustain both the function and value of vegetation assets
■ To enhance public safety by carefully maintaining the health of onsite
vegetation and to reduce liability
■ To contain costs associated with site restoration
■ To reduce or avoid soil compaction and degradation
■ To avoid physical injury to existing trees
■ To avoid root injury to trees and other vegetation
■ To protect soils and hydraulic integrity of the entire site
■ To protect existing irrigation, utilities and underground drainage
■ To prevent sediment -laden and/or polluted runoff from entering drainage
systems and water bodies (streams, wetlands, lakes).
Definitions Critical Root Zone (CRZ) - The circular area around the base of a tree
calculated as the distance to the furthest extent to the tree's dripline.
Development Project - Any construction activity including demolition, grading,
drainage improvements, new construction of main house or accessory structures,
added square footage to existing main house or accessory structures, site
preparation and landscaping.
Diameter at Breast Height (DBH) - The diameter of the tree trunk at four and
one-half feet (or 54 inches) above natural grade level. The diameter may be
calculated by using the following formula: DBH= circumference at 4.5-feet x
3.14. To determine the DBH of multi -trunk trees or measuring trees on slopes,
consult the current Guide for Plant Appraisal, published by the Council of Tree
and Landscape Appraisers.
Drip line - The circular area around the base of a tree measured by the furthest
lateral extent of the foliage.
Project Arborist - A qualified professional who is qualified to evaluate trees
such as a Certified Arborist, a Registered Consulting Arborist, a Licensed
Landscape Architect or a Certified Forester. The project arborist is responsible
for decisions related to vegetation on site before, during and after construction.
Tree Protection Requirements Page 231
Project Manager - The person assigned to the construction project by the
department or the contractor who is responsible for managing the overall project.
Project management duties include schedule, budget, and related logistics,
including construction site management.
Tree Protection Site Plan (Base Map) - A set of drawings that show existing
site conditions and proposed landscape improvements, including trees to be
removed, relocated or to be retained. Site plans shall include the following
minimum information that may affect trees:
A. Surveyed location, species, size, drip line area of significant (including trees
located on neighboring property that overhang the project site) and Street Trees
within 30-feet of the project site.
B. Paving, concrete, trenching or grade change located within the Tree
Protection Zone (TPZ).
C. Existing and proposed utility pathways.
D. Surface and subsurface drainage and aeration systems to be used.
E. Walls, tree wells, retaining walls and grade change barriers, both temporary
and permanent.
F. Landscaping, irrigation and lighting within TPZ of trees.
G. All of the final approved site plan sheets shall reference tree protection
instructions.
Significant Tree - A healthy evergreen or deciduous tree, eight inches in
diameter or greater at four feet above existing grade. (Land Use Code 20.50.046)
Street Tree - means any tree growing within the street right-of-way, outside of
private property.
Tree Appraisal - means a method of determining the monetary value of a tree as
it relates to the real estate value of the property, neighborhood, or community.
Tree Protection Plan (TPP) - A plan prepared by a certified arborist that
outlines measures to protect and preserve trees.
Tree Protection Zone (TPZ) - The circular area around a tree calculated as one
foot of radius for every inch of DBH, or at least 6 feet, whichever is greater that
is required to be protected with a fenced enclosure.
Tree Protection Fencing - A temporary enclosure erected around a tree to be
protected at the boundary of the tree protection zone. Tree protection fencing
should consist of six 6 foot high chain link fence, mounted on two inch diameter
metal posts, driven into the ground to a depth of at least 2-feet at no more than
10-foot spacing.
Warning Sign - A warning sign shall be prominently displayed on each fence.
The sign shall be a minimum of 8.5 x 11-inches and clearly state: "WARNING —
Tree Protection Zone - This fence shall not be removed and any injury to this or
these trees is subject to penalty according to BCC 14.06.100."
Conditions of Use Trees and vegetation can be impacted during construction in many ways and
often times the damage is not seen for several months or even years after the
construction is completed. Proper tree protection can benefit not only the tree by
reducing stress during construction but also the developer and property owner by
reducing long term costs associated with future maintenance. The cost of
Tree Protection Requirements Page 232
removing a tree killed by construction after development is usually greater than
the cost of protecting the tree during construction.
Common types of tree injuries that occur during construction may include:
■ Mechanical injury to roots, trunk or branches
■ Compaction of soil by storing of materials or equipment, which degrades the
functioning of roots, inhibits the development of new roots and restricts drainage.
■ Changes in existing grade which can cut or suffocate roots
■ Alteration of the water table - either raising or lowering
■ Changes in drainage patterns that promotes erosion or excessive
accumulation of runoff
■ Sterile soil conditions associated with stripping off topsoil
■ Damage to roots from dumping of liquids or rinsing of construction
equipment
Not all damage occurs to trees and vegetation during the actual construction of
buildings or structures. Trees are often damage during the landscaping phase
after the heavy equipment and workers have left. Installing irrigation, applying
topsoil and turf installation also causes damage to trees. All construction -related
impacts can produce long-term maintenance problems that can be avoided by
following the BMPs set forth in the remainder of this chapter.
Planning & Permitting Phase
■ Inventory and evaluate all existing trees on the site and trees immediately
adjacent with driplines or expected root zones extending onto the project site.
The inventory and evaluation shall include, but not be limited to the following
information:
Tree species
Tree size in DBH and canopy spread
Tree condition or observed defects
Tree numbers that are included in an inventory table
A calculation of the total diameter inches of significant trees on the site
along with an indication of the interior or perimeter location of the tree,
if applicable to the proposed development type and tree retention.
Tree map showing the location of the existing significant trees on the site
with numbers corresponding to the tree inventory table.
■ Submit a Tree Protection Plan (TPP) prepared by a Project Arborist that
includes the following information:
Location of and description all significant trees that will remain on the
project site per LUC 20.20.900
Illustration of the Tree Protection Zone (TPZ) for each tree is a radius of
1.5 feet for every inch of DBH or a minimum of 6 feet, whichever is
greater.
Tree Protection Requirements Page 233
The TPZ will regularly exceed the Critical Root Zone (CRZ), which is
the outer edge of the tree's canopy, or drip line. The reduction of TPZ
closer to the CRZ must be accompanied by mitigating measures and be
approved in writing by the City of Bellevue. The TPZ may not be
smaller than the CRZ.
Description of expected tree protection techniques that will be used on
the project as per the Land Use Code and the Clearing and Grading Code
All tree removal and pruning needed to make room for future structures
and construction equipment should also be drawn on the base map
A timetable for project meetings with the Project Team including a pre -
construction meeting and the schedule for the Project Arborist
monitoring.
Calculation of appraisal amounts to be collected by the City as an
assurance device in the form of a deposit equal to the tree appraisal value
of all protected trees as determined under the methods described in the
Guide for Establishing Value of Trees and Other Plants, published by the
International Society of Arboriculture.
Pre -Construction Site Preparation Phase
■ Stage equipment away from trees and vegetation to be retained so that
existing plants and their roots are protected.
■ Fence off with chain link or construction fencing all entry and exit routes.
When planning routes, avoid utility access corridors.
■ Protect irrigation and drainage systems shall from damage unless plans call
for renovation of such systems.
■ Stake and/or flag clearing limits and tree protection to be verified and
approved by the City's clearing and grading inspector at the required
preconstruction meeting.
■ Project Arborist will supervise and verify the following tree protection
measures are in place and comply with the approved TPP:
A 6" layer of coarse mulch or woodchips is to be placed beneath the Tree
Protection Zone (TPZ) of the protected trees. Mulch is to be kept 12"
from the trunk.
Trees that have been identified in the site inventory as posing a health or
safety risk may be removed or pruned by no more than one-third, subject
to approval of the required permit by the City of Bellevue. Pruning of
existing limbs and roots shall occur under the direction of the Project
Arborist.
Tree Protection Fencing of 6' chain link fencing shall be installed around
the TPZ of protected tree(s). The fencing can be moved within the TPZ
if authorized by the Clearing and Grading Inspector and the Project
Arborist but not closer than 2' from the trunk of any tree. Fence posts
shall be 1.5" in diameter and are to be driven 2' into the ground. The
distance between posts shall not be more than 10'.
Tree protection fencing shall have a warning signs prominently installed
on each fence at 20-foot intervals. The sign shall be a minimum 8.5-
Tree Protection Requirements Page 234
Construction Phase
inches x I I -inches and clearly state: "WARNING - Tree Protection
Zone"
Movable barriers of chain link fencing secured to cement blocks may be
substituted for "fixed" fencing if the Project Arborist and City Staff
agree that the fencing will have to be moved to accommodate certain
phases of construction. The builder may not move the fence without
authorization from the Project Arborist and City Staff.
Should temporary access into the TPZ be approved, an additional 3"
layer of gravel and 3/4" plywood shall be placed over the CRZ.
During the Construction phase, ensure the TPP is being followed and report any
conflicts or deviations to the City of Bellevue Clearing and Grading Inspector.
Monitor construction activities that require encroachment within the TPZ, such
as grading or trenching.
Avoid the following conditions:
1. Allowing run off or spillage of damaging materials into the approved TPZ.
2. Storing construction materials or portable toilets, stockpiling of soil, or
parking or driving vehicles within the TPZ.
3. Cutting, breaking, skinning, or bruising roots, branches, or trunks without
first obtaining authorization from the Project Arborist.
4. Discharging exhaust into foliage.
5. Securing cable, chain, or rope to trees or shrubs.
6. Trenching, digging, tunneling or otherwise excavating within the CRZ or
TPZ of the tree(s) without first obtaining authorization from the Project Arborist.
Periodically inspect during construction - at four -week intervals - to assess and
monitor the effectiveness of the TPP and provide recommendations for any
additional care or treatment. More frequent may be required based on the TPP.
The following activities should be observed and inspected by the project arborist
during the construction phase to ensure compliance with the approved TPP:
1. Only excavation by hand or compressed air shall be allowed within the TPZ
of trees. Machine trenching shall not be allowed.
2. In order to avoid injury to tree roots, when a trenching machine is being used
outside of the TPZ of trees, and roots are encountered smaller than 2", the wall of
the trench adjacent to the trees shall be hand trimmed, making clear, clean cuts
through the roots. All damaged, torn and cut roots shall be given a clean cut to
remove ragged edges, which promote decay. Trenches shall be filled within 24
hours, but where this is not possible, the side of the trench adjacent to the trees
shall be kept shaded with four layers of dampened, untreated burlap, wetted as
frequently as necessary to keep the burlap wet. Roots 2" or larger, when
encountered, shall be reported immediately to the Project Arborist, who will
decide whether the Contractor may cut the root as mentioned above or shall
excavate by hand or with compressed air under the root. All exposed roots are to
be protected with dampened burlap.
3. Route pipes outside of the TPZ of a protected tree to avoid conflict with
roots. Where it is not possible to reroute pipes or trenches, bore or tunnel beneath
Tree Protection Requirements Page 235
Post -Construction
the TPZ of the tree. The boring shall take place not less than 3' below the
surface of the soil in order to avoid encountering "feeder" roots. All boring
equipment must be staged outside of the TPZ.
4. All grade changes adjacent to the TPZ of a significant tree shall be
supervised by the Project Arborist. Cuts or Fills of soil that are adjacent to the
TPZ will have a retaining wall system designed in consultation with the Project
Arborist and approved in writing by City Staff.
5. Any damage due to construction activities shall be reported to the Project
Arborist and City Staff within six hours so that remedial action can be taken.
6. The Project Arborist shall be responsible for the preservation of the
designated trees. Should the builder fail to follow the tree protection
specifications, it shall be the responsibility of the Project Arborist to report the
matter to City Staff as an issue of non-compliance.
The Post -Construction Phase begins when the equipment leaves and the new
tenants move in. Important follow-up monitoring of the protected trees will help
ensure their survival and identify signs of early stress.
The applicant shall arrange with the Project Arborist for the long-term care and
monitoring of preserved trees by complying with the following conditions:
1. Complete post -construction tree maintenance, including pruning, mulching,
fertilization, irrigation, and soil aeration where necessary.
2. Remove, by hand, all soil and root protection material such as wood chips,
gravel and plywood.
3. Provide for remediation of compacted soil by methods such as aeration or
vertical mulching.
4. Apply at least 1 inch of water per week by deep watering in the absence of
adequate rainfall.
5. Fertilize trees with slow released phosphorus, potassium, calcium,
magnesium, and other macro- and micro -nutrients as indicated by a soil test, but
wait at least one year to apply any nitrogen.
6. Fertilize lightly with slow release nitrogen after 1 year, and then make annual
light nitrogen applications for the next 3 to 5 years.
7. Inspect trees annually for at least 3 and up to 5 years after construction to
look for changes in condition and signs of insects or disease, and to determine
maintenance needs.
8. Remove trees that are badly damaged or are in irreversible decline as
determined by the Project Arborist and City Staff.
9. Continue to protect not only the large, established trees on the site but also
those newly planted in the landscape as per LUC 20.20.520.K.
10. Provide annual inspection reports to the City.
Tree Protection Requirements Page 236
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• Protective fencing to remain installed at all times.
• Working within TPZ restricted to City approved
personnel and supervised by Project Arborist.
• No storage of equipment or materials within TPZ, or
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washing of equipment in or within 10' of TPZ.
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Tree Protection Fencing
• Minimum 6' chain link fencing installed completely
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Tree Protection Requirements Page 237
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Legend
Aoer macmphyllum
(bigleaf maple)
OFraxinus laSfolia
(Oregon white ash)
Pseudotsuga menbead
(Douglas -fir)
Existing fee to be
removed
Arborist: Johnny Appleseed
Contact: 425-452-41 BB
General Notes
1. 6'-0" HIGH CHAIN LINK FENCE IS PLACED
1.5 FEET PER INCH DBH AND DEFINES
THETREE PROTECTION ZONE (TPZ).
2. STAKES WILL BE 1.5" IN DIAMETER,
DRIVEN INTO GROUND 2' AND PLACED
NO FURTHER THAN 10 FEET APART.
3. TREE PROTECTION SIGNAGE SHALL BE
INSTALLED AT INTERVALS NO LESS
THAN 20' APART. SEE TREE
PROTECTION SIGNAGE DETAIL # TP-4.
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City of TREE PROTECTION SITE PLAN SCALE NONE
Bellevue REVISION DATE 1/10
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TREE PROTECTION SIGNAGE
DETAIL#TP_4.
EXISTING TREE PIT
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DURING CURB REPLACEMENT, ROOTS WITHIN 6INCHES OF DEPTH FROM
BOTTOM OF CURB SHALL BE CUT WITH A CLEAN, SHARP SAW. ROOTS
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GREATERTHAN 6 INCHES DEEP SHALL BE PRESERVED. UNLESS
SPECIFICALLY DIRECTED BY C.O.B.
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Tree Protection Requirements Page 239
BMP C105: Stabilized Construction Entrance
Purpose Construction entrances are stabilized to reduce the amount of sediment
transported onto paved roads by vehicles or equipment by constructing a
stabilized pad of quarry spalls at entrances to construction sites.
Conditions of Use Construction entrances shall be stabilized wherever traffic will be leaving
a construction site and traveling on paved roads or other paved areas
within 1,000 feet of the site.
On large commercial, highway, and road projects, the designer should
include enough extra materials in the contract to allow for additional
stabilized entrances not shown in the initial CSWPPP. It is difficult to
determine exactly where access to these projects will take place; additional
materials will enable the contractor to install them where needed.
Design and • See Figure 4.2 for details. Note: the 100' minimum length of the
Installation entrance shall be reduced to the maximum practicable size when the
Specifications size or configuration of the site does not allow the full length (100').
• A separation geotextile shall be placed under the spalls to prevent
fine sediment from pumping up into the rock pad. The geotextile
shall meet the following standards:
Grab Tensile Strength (ASTM D4751)
200 psi min.
Grab Tensile Elongation (ASTM D4632)
30% max.
Mullen Burst Strength (ASTM D3786-80a)
400 psi min.
AOS (ASTM D4751)
20-45 (U.S. standard sieve size)
• Consider early installation of the first lift of asphalt in areas that will
paved; this can be used as a stabilized entrance. Also consider the
installation of excess concrete as a stabilized entrance. During large
concrete pours, excess concrete is often available for this purpose.
• Hog fuel (wood -based mulch) may be substituted for or combined with
quarry spalls in areas that will not be used for permanent roads. Hog
fuel is generally less effective at stabilizing construction entrances and
should be used only at sites where the amount of traffic is very limited.
Hog fuel is not recommended for entrance stabilization in urban areas.
The effectiveness of hog fuel is highly variable and it generally
requires more maintenance than quarry spalls. The inspector may at
any time require the use of quarry spalls if the hog fuel is not
preventing sediment from being tracked onto pavement or if the hog
fuel is being carried onto pavement. Hog fuel is prohibited in
permanent roadbeds because organics in the subgrade soils cause
degradation of the subgrade support over time.
• Fencing (see BMPs C 103 and C 104) shall be installed as necessary to
restrict traffic to the construction entrance.
Clearing & Grading Development Standards Page 86
• Whenever possible, the entrance shall be constructed on a firm,
compacted subgrade. This can substantially increase the effectiveness
of the pad and reduce the need for maintenance.
Maintenance • Quarry spalls (or hog fuel) shall be added if the pad is no longer in
Standards accordance with the specifications.
• If the entrance is not preventing sediment from being tracked onto
pavement, then alternative measures to keep the streets free of
sediment shall be used. This may include street sweeping, an increase
in the dimensions of the entrance, or the installation of a wheel wash.
• Any sediment that is tracked onto pavement shall be removed by
shoveling or street sweeping. The sediment collected by sweeping
shall be removed or stabilized on site. The pavement shall not be
cleaned by washing down the street, except when sweeping is
ineffective and there is a threat to public safety. If it is necessary to
wash the streets, the construction of a small sump shall be considered.
The sediment would then be washed into the sump where it can be
controlled.
• Any quarry spalls that are loosened from the pad, which end up on the
roadway shall be removed immediately.
• If vehicles are entering or exiting the site at points other than the
construction entrance(s), fencing (see BMPs C 103 and C 104) shall be
installed to control traffic.
• Upon project completion and site stabilization, all construction
accesses intended as permanent access for maintenance shall be
permanently stabilized.
Driveway shall meet the
requirements of the
permitting agency
It is recommended that
the entrance be
crowned so that runoff
cad drains off the pad
EyJsi�r9 F i
j00.
7
Install driveway culvert
if there is a roadside
ditch present
4"-8" quarry spalls
Geotextile
7
12" min. thickness _T
Provide full width of
ingress/egress area
Figure 4.2 — Stabilized Construction Entrance
Clearing & Grading Development Standards Page 87
BMP C233: Silt Fence
Purpose Use of a silt fence reduces the transport of coarse sediment from a
construction site by providing a temporary physical barrier to sediment
and reducing the runoff velocities of overland flow. See Figure 4.19 for
details on silt fence construction.
Conditions of Use Silt fence may be used downslope of all disturbed areas.
Silt fence is not intended to treat concentrated flows, nor is it intended
to treat substantial amounts of overland flow. Any concentrated flows
must be conveyed through the drainage system to a sediment pond.
The only circumstance in which overland flow can be treated solely by
a silt fence, rather than by a sediment pond, is when the area draining
to the fence is one acre or less and flow rates are less than 0.5 cfs.
• Silt fences should not be constructed in streams or used in V-shaped
ditches. They are not an adequate method of silt control for anything
deeper than sheet or overland flow.
Joints in filter fabric shall be spliced at
posts. Use staples, wire rings or 2"x2" by 14 Ga. wire or
equivalent to attach fabric to posts equivalent if standard
strength 6bric used
Filter fabric
II I =
E
N
-
1=1 I I III III-1 I I-1 I I-1 I I-1 I I-1 11=1I 1=1 11=1 11=1 11=1 I I III I I IJ I II I II I I --"�-1 I1=1 ;?
6' max= R- Minimum 4"x4" trench IM, -11 11-11 E
g N
Backfill trench with native soil
Post spacing may be increased or 3/4"-1.5" washed gravel
to 8' if wire backing is used
2"x2" wood posts, steel fence
posts, or equivalent
Figure 4.19 — Silt Fence
Design and • Drainage area of 1 acre or less or in combination with sediment basin
Installation in a larger site.
Specifications . Maximum slope steepness (normal (perpendicular) to fence line) 1:1.
• Maximum sheet or overland flow path length to the fence of 100 feet.
• No flows greater than 0.5 cfs.
• The geotextile used shall meet the following standards. All geotextile
properties listed below are minimum average roll values (i.e., the test
result for any sampled roll in a lot shall meet or exceed the values
shown in Table 4.10):
Clearing & Grading Development Standards — Appendix A2 Page 173
Table 4.10
Geotextile Standards
Polymeric Mesh AOS
0.60 mm maximum for slit film wovens (#30 sieve). 0.30
(ASTM D4751)
mm maximum for all other geotextile types (#50 sieve).
0.15 mm minimum for all fabric types (#100 sieve).
Water Permittivity
0.02 sec-1minimum
(ASTM D4491)
Grab Tensile Strength
1801bs. Minimum for extra strength fabric.
(ASTM D4632)
100 lbs minimum for standard strength fabric.
Grab Tensile Strength
30% maximum
(ASTM D4632)
Ultraviolet Resistance
70% minimum
(ASTM D4355)
• Standard strength fabrics shall be supported with wire mesh, chicken
wire, 2-inch x 2-inch wire, safety fence, or jute mesh to increase the
strength of the fabric. Silt fence materials are available that have
synthetic mesh backing attached.
• Filter fabric material shall contain ultraviolet ray inhibitors and
stabilizers to provide a minimum of six months of expected usable
construction life at a temperature range of 0°F. to 120°F.
• 100 percent biodegradable silt fence is available that is strong, long
lasting, and can be left in place after the project is completed, if
permitted by local regulations.
• Standard Notes for construction plans and specifications follow. Refer
to Figure 4.19 for standard silt fence details.
The contractor shall install and maintain temporary silt fences at the
locations shown in the Plans. The silt fences shall be constructed in
the areas of clearing, grading, or drainage prior to starting those
activities. A silt fence shall not be considered temporary if the silt
fence must function beyond the life of the contract. The silt fence
shall prevent soil carried by runoff water from going beneath, through,
or over the top of the silt fence, but shall allow the water to pass
through the fence.
The minimum height of the top of silt fence shall be 2 feet and the
maximum height shall be 2%2 feet above the original ground surface.
The geotextile shall be sewn together at the point of manufacture, or at
an approved location as determined by the Engineer, to form geotextile
lengths as required. All sewn seams shall be located at a support post.
Alternatively, two sections of silt fence can be overlapped, provided
the Contractor can demonstrate, to the satisfaction of the Engineer, that
the overlap is long enough and that the adjacent fence sections are
close enough together to prevent silt laden water from escaping
through the fence at the overlap.
Clearing & Grading Development Standards — Appendix A2 Page 174
The geotextile shall be attached on the up -slope side of the posts and
support system with staples, wire, or in accordance with the
manufacturer's recommendations. The geotextile shall be attached to
the posts in a manner that reduces the potential for geotextile tearing at
the staples, wire, or other connection device. Silt fence back-up
support for the geotextile in the form of a wire or plastic mesh is
dependent on the properties of the geotextile selected for use. If wire
or plastic back-up mesh is used, the mesh shall be fastened securely to
the up -slope of the posts with the geotextile being up -slope of the
mesh back-up support.
The geotextile at the bottom of the fence shall be buried in a trench to
a minimum depth of 4 inches below the ground surface. The trench
shall be backfilled and the soil tamped in place over the buried portion
of the geotextile, such that no flow can pass beneath the fence and
scouring can not occur. When wire or polymeric back-up support
mesh is used, the wire or polymeric mesh shall extend into the trench a
minimum of 3 inches.
The fence posts shall be placed or driven a minimum of 18 inches. A
minimum depth of 12 inches is allowed if topsoil or other soft
subgrade soil is not present and a minimum depth of 18 inches cannot
be reached. Fence post depths shall be increased by 6 inches if the
fence is located on slopes of 3:1 or steeper and the slope is
perpendicular to the fence. If required post depths cannot be obtained,
the posts shall be adequately secured by bracing or guying to prevent
overturning of the fence due to sediment loading.
Silt fences shall be located on contour as much as possible, except at
the ends of the fence, where the fence shall be turned uphill such that
the silt fence captures the runoff water and prevents water from
flowing around the end of the fence.
If the fence must cross contours, with the exception of the ends of the
fence, gravel check dams placed perpendicular to the back of the fence
shall be used to minimize concentrated flow and erosion along the
back of the fence. The gravel check dams shall be approximately 1-
foot deep at the back of the fence. It shall be continued perpendicular
to the fence at the same elevation until the top of the check dam
intercepts the ground surface behind the fence. The gravel check dams
shall consist of crushed surfacing base course, gravel backfill for
walls, or shoulder ballast. The gravel check dams shall be located
every 10 feet along the fence where the fence must cross contours.
The slope of the fence line where contours must be crossed shall not
be steeper than 3:1.
Wood, steel or equivalent posts shall be used. Wood posts shall have
minimum dimensions of 2 inches by 2 inches by 3 feet minimum
length, and shall be free of defects such as knots, splits, or gouges.
Steel posts shall consist of either size No. 6 rebar or larger, ASTM A
120 steel pipe with a minimum diameter of 1-inch, U, T, L, or C shape
Clearing & Grading Development Standards — Appendix A2 Page 175
steel posts with a minimum weight of 1.35 lbs./ft. or other steel posts
having equivalent strength and bending resistance to the post sizes
listed. The spacing of the support posts shall be a maximum of 6 feet.
Fence back-up support, if used, shall consist of steel wire with a
maximum mesh spacing of 2 inches, or a prefabricated polymeric
mesh. The strength of the wire or polymeric mesh shall be equivalent
to or greater than 180 lbs. grab tensile strength. The polymeric mesh
must be as resistant to ultraviolet radiation as the geotextile it supports.
• Silt fence installation using the slicing method specification details
follow. Refer to Figure 4.20 for slicing method details.
The base of both end posts must be at least 2 to 4 inches above the top
of the silt fence fabric on the middle posts for ditch checks to drain
properly. Use a hand level or string level, if necessary, to mark base
points before installation.
Install posts 3 to 4 feet apart in critical retention areas and 6 to 7 feet
apart in standard applications.
Install posts 24 inches deep on the downstream side of the silt fence,
and as close as possible to the fabric, enabling posts to support the
fabric from upstream water pressure.
Install posts with the nipples facing away from the silt fence fabric.
Attach the fabric to each post with three ties, all spaced within the top
8 inches of the fabric. Attach each tie diagonally 45 degrees through
the fabric, with each puncture at least 1 inch vertically apart. In
addition, each tie should be positioned to hang on a post nipple when
tightening to prevent sagging.
Wrap approximately 6 inches of fabric around the end posts and secure
with 3 ties.
No more than 24 inches of a 36-inch fabric is allowed above ground
level.
The rope lock system must be used in all ditch check applications.
The installation should be checked and corrected for any deviation
before compaction. Use a flat -bladed shovel to tuck fabric deeper into
the ground if necessary.
Compaction is vitally important for effective results. Compact the soil
immediately next to the silt fence fabric with the front wheel of the
tractor, skid steer, or roller exerting at least 60 pounds per square inch.
Compact the upstream side first and then each side twice for a total of
four trips.
• Any damage shall be repaired immediately.
Maintenance 0 If concentrated flows are evident uphill of the fence, they must be
Standards intercepted and conveyed to a sediment pond.
• It is important to check the uphill side of the fence for signs of the
fence clogging and acting as a barrier to flow and then causing
channelization of flows parallel to the fence. If this occurs, replace the
fence or remove the trapped sediment.
Clearing & Grading Development Standards — Appendix A2 Page 176
• Sediment deposits shall either be removed when the deposit reaches
approximately one-third the height of the silt fence, or a second silt
fence shall be installed.
• If the filter fabric (geotextile) has deteriorated due to ultraviolet
breakdown, it shall be replaced.
Ponding height POST SPACING:
max. 24- 7' max. on open runs
11 4' max. on pooling areas
Attach fabric to
upstream side o1 post
FLOW
Drive over each side of
.,Itfence 2 to 4 times
POST DEPTH:
As much below ground
with davl ce exerting
60 p.s.l. or greater
as fabric above ground
100%cornpacudw
100%compaction
//\
%\
No more than 24" of a 36" fabric
is allowed above ground.
Roll of sift fence
Silt Fence
t a..
Wmm
1
Horizontal chtrel point Slicing blade
(76 mm WdtN (18 mm width)
Vibratory plow is not acceptable because of horizontal compaction
Post
installed
after
compaction
Completed Installation
Figure 4.20 — Silt Fence Installation by Slicing Method
Clearing & Grading Development Standards — Appendix A2 Page 177
BMP C235: Straw Wattles
Purpose Straw wattles are temporary erosion and sediment control barriers
consisting of straw that is wrapped in biodegradable tubular plastic or
similar encasing material. They reduce the velocity and can spread the
flow of rill and sheet runoff, and can capture and retain sediment. Straw
wattles are typically 8 to 10 inches in diameter and 25 to 30 feet in length.
The wattles are placed in shallow trenches and staked along the contour of
disturbed or newly constructed slopes. See Figure 4.21 for typical
construction details.
Conditions of Use • Disturbed areas that require immediate erosion protection.
• Exposed soils during the period of short construction delays, or over
winter months.
• On slopes requiring stabilization until permanent vegetation can be
established.
• Straw wattles are effective for one to two seasons.
• If conditions are appropriate, wattles can be staked to the ground using
willow cuttings for added revegetation.
• Rilling can occur beneath wattles if not properly entrenched and water
can pass between wattles if not tightly abutted together.
Design Criteria • It is critical that wattles are installed perpendicular to the flow
direction and parallel to the slope contour.
• Narrow trenches should be dug across the slope on contour to a depth
of 3 to 5 inches on clay soils and soils with gradual slopes. On loose
soils, steep slopes, and areas with high rainfall, the trenches should be
dug to a depth of 5 to 7 inches, or 1/2 to 2/3 of the thickness of the
wattle.
• Start building trenches and installing wattles from the base of the slope
and work up. Excavated material should be spread evenly along the
uphill slope and compacted using hand tamping or other methods.
• Construct trenches at contour intervals of 3 to 30 feet apart depending
on the steepness of the slope, soil type, and rainfall. The steeper the
slope the closer together the trenches.
• Install the wattles snugly into the trenches and abut tightly end to end.
Do not overlap the ends.
• Install stakes at each end of the wattle, and at 4-foot centers along
entire length of wattle.
• If required, install pilot holes for the stakes using a straight bar to drive
holes through the wattle and into the soil.
• At a minimum, wooden stakes should be approximately 3/4 x 3/4 x 24
inches. Willow cuttings or 3/8-inch rebar can also be used for stakes.
Clearing & Grading Development Standards — Appendix A2 Page 179
Maintenance • Stakes should be driven through the middle of the wattle, leaving 2 to 3
Standards inches of the stake protruding above the wattle.
• Wattles may require maintenance to ensure they are in contact with soil
and thoroughly entrenched, especially after significant rainfall on steep
sandy soils.
• Inspect the slope after significant storms and repair any areas where
wattles are not tightly abutted or water has scoured beneath the wattles.
3'-4'
(1.2m)
Straw Rolls Must �\
Be Placed Along �j\\
Slope Contours \
Adjacent rolls shall
\ tightly abut
\y
/
10'-25' (3-8m)
Spacing Dependson \\�\
Slope 'l Type Se
Steepness /\��\\ \ and nativs anic ter,
eseeds
captured behind the rolls.
Y-5" (75-125mm)
(200-250mm)
Live Stake\\
�Y-
��\ 1" X 1" Stake
i not to scale (25 x 25mm)
I �\
NOTE:
1. Straw roll installation requires the placement and secure staking of the roll in a trench, Y-5" (75-125mm)
deep, dug on contour. runoff must not be allowed to run under or around roll.
Figure 4.21 — Straw Wattles
Clearing & Grading Development Standards — Appendix A2 Page 180
BMP C121: Mulching
Purpose The purpose of mulching soils is to provide immediate temporary
protection from erosion. Mulch also enhances plant establishment by
conserving moisture, holding fertilizer, seed, and topsoil in place, and
moderating soil temperatures. There is an enormous variety of mulches
that can be used. Only the most common types are discussed in this
section.
Conditions of Use As a temporary cover measure, mulch should be used:
• On disturbed areas that require cover measures for less than 30 days.
• As a cover for seed during the wet season and during the hot summer
months.
• During the wet season on slopes steeper than 3H:1 V with more than 10
feet of vertical relief.
• Mulch may be applied at any time of the year and must be refreshed
periodically.
Design and For mulch materials, application rates, and specifications, see Table 4.7.
Installation Note: Thicknesses may be increased for disturbed areas in or near
Specifications sensitive areas or other areas highly susceptible to erosion.
Mulch used within the ordinary high-water mark of surface waters should
be selected to minimize potential flotation of organic matter. Composted
organic materials have higher specific gravities (densities) than straw,
wood, or chipped material.
Maintenance • The thickness of the cover must be maintained.
Standards • Any areas that experience erosion shall be remulched and/or protected
with a net or blanket. If the erosion problem is drainage related, then
the problem shall be fixed and the eroded area remulched.
Clearing & Grading Development Standards Page 99
Table 4.7
Mulch Standards and Guidelines
Mulch
Application
Material
Quality Standards
Rates
Remarks
Straw
Air-dried; free from
2"-3" thick; 5
Cost-effective protection when applied with adequate
undesirable seed and
bales per 1000 sf
thickness. Hand -application generally requires greater
coarse material.
or 2-3 tons per
thickness than blown straw. The thickness of straw may be
acre
reduced by half when used in conjunction with seeding. In
windy areas straw must be held in place by crimping, using a
tackifier, or covering with netting. Blown straw always has
to be held in place with a tackifier as even light winds will
blow it away. Straw, however, has several deficiencies that
should be considered when selecting mulch materials. It
often introduces and/or encourages the propagation of weed
species and it has no significant long-term benefits. Straw
should be used only if mulches with long-term benefits are
unavailable locally. It should also not be used within the
ordinary high-water elevation of surface waters (due to
flotation).
Hydromulch
No growth
Approx. 25-30
Shall be applied with hydromulcher. Shall not be used
inhibiting factors.
lbs per 1000 sf
without seed and tackifier unless the application rate is at
or 1500 - 2000
least doubled. Fibers longer than about 3/4-1 inch clog
lbs per acre
hydromulch equipment. Fibers should be kept to less than 3/4
inch.
Composted
No visible water or
2" thick min.;
More effective control can be obtained by increasing
Mulch and
dust during
approx. 100 tons
thickness to 3". Excellent mulch for protecting final grades
Compost
handling. Must be
per acre (approx.
until landscaping because it can be directly seeded or tilled
purchased from
800 lbs per yard)
into soil as an amendment. Composted mulch has a coarser
supplier with Solid
size gradation than compost. It is more stable and practical
Waste Handling
to use in wet areas and during rainy weather conditions.
Permit (unless
exempt).
Chipped Site
Average size shall
2" minimum
This is a cost-effective way to dispose of debris from
Vegetation
be several inches.
thickness
clearing and grubbing, and it eliminates the problems
Gradations from
associated with burning. Generally, it should not be used on
fines to 6 inches in
slopes above approx. 10% because of its tendency to be
length for texture,
transported by runoff. It is not recommended within 200
variation, and
feet of surface waters. If seeding is expected shortly after
interlocking
mulch, the decomposition of the chipped vegetation may tie
properties.
up nutrients important to grass establishment.
Wood -based
No visible water or
2" thick; approx.
This material is often called "hog or hogged fuel." It is
Mulch
dust during
100 tons per acre
usable as a material for Stabilized Construction Entrances
handling. Must be
(approx. 800 lbs.
(BMP C105) and as a mulch. The use of mulch ultimately
purchased from a
per cubic yard)
improves the organic matter in the soil. Special caution is
supplier with a Solid
advised regarding the source and composition of wood -
Waste Handling
based mulches. Its preparation typically does not provide
Permit or one
any weed seed control, so evidence of residual vegetation in
exempt from solid
its composition or known inclusion of weed plants or seeds
waste regulations.
should be monitored and prevented (or minimized).
Clearing & Grading Development Standards Page 100
BMP C123: Plastic Covering
Purpose Plastic covering provides immediate, short-term erosion protection to
slopes and disturbed areas.
Conditions of Plastic covering may be used on disturbed areas that require cover
Use measures for less than 30 days, except as stated below.
• Plastic is particularly useful for protecting cut and fill slopes and
stockpiles. Note: The relatively rapid breakdown of most polyethylene
sheeting makes it unsuitable for long-term (greater than six months)
applications.
Clear plastic sheeting can be used over newly -seeded areas to create a
greenhouse effect and encourage grass growth if the hydroseed was
installed too late in the season to establish 75 percent grass cover, or if
the wet season started earlier than normal. Clear plastic should not be
used for this purpose during the summer months because the resulting
high temperatures can kill the grass.
• Due to rapid runoff caused by plastic sheeting, this method shall not be
used upslope of areas that might be adversely impacted by
concentrated runoff. Such areas include steep and/or unstable slopes.
• While plastic is inexpensive to purchase, the added cost of installation,
maintenance, removal, and disposal make this an expensive material,
up to $1.50-2.00 per square yard.
Whenever plastic is used to protect slopes, water collection measures
must be installed at the base of the slope. These measures include
plastic -covered berms, channels, and pipes used to covey clean
rainwater away from bare soil and disturbed areas. At no time is clean
runoff from a plastic covered slope to be mixed with dirty runoff from
a project.
• Other uses for plastic include:
1. Temporary ditch liner;
2. Pond liner in temporary sediment pond;
3. Liner for bermed temporary fuel storage area if plastic is not
reactive to the type of fuel being stored;
4. Emergency slope protection during heavy rains; and,
5. Temporary drainpipe ("elephant trunk") used to direct water.
Clearing & Grading Development Standards Page 105
Design and Plastic slope cover must be installed as follows:
Installation 1. Run plastic up and down slope, not across slope;
Specifications
2. Plastic may be installed perpendicular to a slope if the slope length
is less than 10 feet;
3. Minimum of 8-inch overlap at seams;
4. On long or wide slopes, or slopes subject to wind, all seams should
be taped;
5. Place plastic into a small (12-inch wide by 6-inch deep) slot trench
at the top of the slope and backfill with soil to keep water from
flowing underneath;
6. Place sand filled burlap or geotextile bags every 3 to 6 feet along
seams and pound a wooden stake through each to hold them in
place;
7. Inspect plastic for rips, tears, and open seams regularly and repair
immediately. This prevents high velocity runoff from contacting
bare soil which causes extreme erosion;
8. Sandbags may be lowered into place tied to ropes. However, all
sandbags must be staked in place.
• Plastic sheeting shall have a minimum thickness of 0.06 millimeters.
• If erosion at the toe of a slope is likely, a gravel berm, riprap, or other
suitable protection shall be installed at the toe of the slope in order to
reduce the velocity of runoff.
Maintenance • Torn sheets must be replaced and open seams repaired.
Standards • If the plastic begins to deteriorate due to ultraviolet radiation, it must
be completely removed and replaced.
• When the plastic is no longer needed, it shall be completely removed.
• Dispose of old tires appropriately.
Clearing & Grading Development Standards Page 106
BMP C206: Level Spreader
Purpose
To provide a temporary outlet for dikes and diversions consisting of
an excavated depression constructed at zero grade across a slope. To
convert concentrated runoff to sheet flow and release it onto areas
stabilized by existing vegetation or an engineered filter strip.
Conditions of Use
Used when a concentrated flow of water needs to be dispersed over a
large area with existing stable vegetation.
• Items to consider are:
1. What is the risk of erosion or damage if the flow may become
concentrated?
2. Is an easement required if discharged to adjoining property?
3. Most of the flow should be as ground water and not as surface
flow.
4. Is there an unstable area downstream that cannot accept
additional ground water?
• Use only where the slopes are gentle, the water volume is
relatively low, and the soil will adsorb most of the low flow
events.
Design and
Use above undisturbed areas that are stabilized by existing vegetation.
Installation
If the level spreader has any low points, flow will concentrate, create
Specifications
channels and may cause erosion.
• Discharge area below the outlet must be uniform with a slope
flatter than 511:1 V.
• Outlet to be constructed level in a stable, undisturbed soil profile
(not on fill).
• The runoff shall not re -concentrate after release unless intercepted
by another downstream measure.
• The grade of the channel for the last 20 feet of the dike or
interceptor entering the level spreader shall be less than or equal
to 1 percent. The grade of the level spreader shall be 0 percent to
ensure uniform spreading of storm runoff.
• A 6-inch high gravel berm placed across the level lip shall consist
of washed crushed rock, 2- to 4-inch or 3/4-inch to 1 %2-inch size.
• The spreader length shall be determined by estimating the peak
flow expected from the 10-year, 24-hour design storm. The length
of the spreader shall be a minimum of 15 feet for 0.1 cfs and shall
increase by 10 feet for each 0.1 cfs thereafter to a maximum of
0.5 cfs per spreader. Use multiple spreaders for higher flows.
0 The width of the spreader should be at least 6 feet.
• The depth of the spreader as measured from the lip should be at
least 6 inches and it should be uniform across the entire length.
• Level spreaders shall be setback from the property line unless
there is an easement for flow.
• Level spreaders, when installed every so often in grassy swales,
keep the flows from concentrating. Materials that can be used
include sand bags, lumber, logs, concrete, and pipe. To function
properly, the material needs to be installed level and on contour.
Figures 4.2.5Figure425 and 4.2.6 provide a cross-section and a
detail of a level spreader. A capped perforated pipe could also be
used as a spreader.
Maintenance The spreader should be inspected after every runoff event to ensure that
Standards it is functioning correctly.
• The contractor should avoid the placement of any material on the
structure and should prevent construction traffic from crossing
over the structure.
• If the spreader is damaged by construction traffic, it shall be
immediately repaired.
Densely vegetated fora
Min. of 100' and slope
less than 5:1
Pressure -Treated 2"x10"
ti
V Min.
hI� 11=
_T
3' Min.
Figure 4.2.5 — Cross Section of Level Spreader
Treated 2"x10" may be abutted end to
Spreader must be level end for max. spreader length of 50'
6" min. 1"min.
6" min. III
IIIIIII IIIIIII
iillllllllli illliiillliiillliiillliiill�illlliillliilllliiillliiilllii Illiitlliiitlliii
18" min. rebar supports
8' max. spacing
Figure 4.2.6 — Detail of Level Spreader
BMP C220: Storm Drain Inlet Protection
Purpose To prevent coarse sediment from entering drainage systems prior to
permanent stabilization of the disturbed area.
Conditions of Use Where storm drain inlets are to be made operational before permanent
stabilization of the disturbed drainage area. Protection should be provided
for all storm drain inlets downslope and within 500 feet of a disturbed or
construction area, unless the runoff that enters the catch basin will be
conveyed to a sediment pond or trap. Inlet protection may be used
anywhere to protect the drainage system. It is likely that the drainage
system will still require cleaning.
Table 4.9 lists several options for inlet protection. All of the methods for storm
drain inlet protection are prone to plugging and require a high frequency of
maintenance. Drainage areas should be limited to 1 acre or less. Emergency
overflows may be required where stormwater ponding would cause a hazard. If
an emergency overflow is provided, additional end -of -pipe treatment may be
required.
Table 4.9
Storm Drain Inlet Protetion
Applicable for
Type of Inlet
Emergency
Paved/ Earthen
Protection
Overflow
Surfaces
Conditions of Use
Drop Inlet Protection
Excavated drop inlet
Yes,
Earthen
Applicable for heavy flows. Easy
protection
temporary
to maintain. Large area
flooding will
Requirement: 30' X 30'/acre
occur
Block and gravel drop
Yes
Paved or Earthen
Applicable for heavy concentrated
inlet protection
flows. Will not pond.
Gravel and wire drop
No
Applicable for heavy concentrated
inlet protection
flows. Will pond. Can withstand
traffic.
Catch basin filters
Yes
Paved or Earthen
Frequent maintenance required.
Curb Inlet Protection
Curb inlet protection
Small capacity
Paved
Used for sturdy, more compact
with a wooden weir
overflow
installation.
Block and gravel curb
Yes
Paved
Sturdy, but limited filtration.
inlet protection
Culvert Inlet Protection
Culvert inlet sediment
1S month expected life.
trap
Clearing & Grading Development Standards — Appendix A2 Page 161
Design and Excavated Drop Inlet Protection - An excavated impoundment around the
Installation storm drain. Sediment settles out of the stormwater prior to entering the
Specifications storm drain.
• Depth 1-2 ft as measured from the crest of the inlet structure.
• Side Slopes of excavation no steeper than 2:1.
• Minimum volume of excavation 35 cubic yards.
• Shape basin to fit site with longest dimension oriented toward the
longest inflow area.
• Install provisions for draining to prevent standing water problems.
• Clear the area of all debris.
• Grade the approach to the inlet uniformly.
• Drill weep holes into the side of the inlet.
• Protect weep holes with screen wire and washed aggregate.
• Seal weep holes when removing structure and stabilizing area.
• It may be necessary to build a temporary dike to the down slope side
of the structure to prevent bypass flow.
Block and Gravel Filter - A barrier formed around the storm drain inlet
with standard concrete blocks and gravel. See Figure 4.14.
• Height 1 to 2 feet above inlet.
• Recess the first row 2 inches into the ground for stability.
• Support subsequent courses by placing a 2x4 through the block
opening.
• Do not use mortar.
• Lay some blocks in the bottom row on their side for dewatering the
pool.
• Place hardware cloth or comparable wire mesh with 1/2-inch openings
over all block openings.
• Place gravel just below the top of blocks on slopes of 2:1 or flatter.
• An alternative design is a gravel donut.
• Inlet slope of 3:1.
• Outlet slope of 2:1.
• 1-foot wide level stone area between the structure and the inlet.
• Inlet slope stones 3 inches in diameter or larger.
• Outlet slope use gravel %2- to 3/4-inch at a minimum thickness of 1-foot.
Clearing & Grading Development Standards — Appendix A2 Page 162
Plan View A
Drain
Grate D amao�o00.o ��o. 2
n'
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o° o o°
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00 ado
Gravel
a o
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°ado°�°��a°
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Section A - A Concrete Block Wire Screen or
Filter Fabric
Gravel BackfillOverflow
Water Ponding Height
p 0 a
oo DSo�� Water o0o�a 1��'00
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\\\\\\\\\ Drop Inlet \\\\\\\\\\
Notes:
1. Drop inlet sediment barriers are to be used for small, nearly level drainage areas. (less than 5%)
2. Excavate a basin of sufficient size adjacent to the drop inlet.
3. The top of the structure (ponding height) must be well below the ground elevation downslope to prevent
runoff from bypassing the inlet. A temporary dike may be necessary on the dowslope side of the structure.
Figure 4.14 — Block and Gravel Filter
Gravel and Wire Mesh Filter - A gravel barrier placed over the top of the inlet.
This structure does not provide an overflow.
• Hardware cloth or comparable wire mesh with %2-inch openings.
• Coarse aggregate.
• Height 1-foot or more, 18 inches wider than inlet on all sides.
• Place wire mesh over the drop inlet so that the wire extends a
minimum of 1-foot beyond each side of the inlet structure.
• If more than one strip of mesh is necessary, overlap the strips.
• Place coarse aggregate over the wire mesh.
Clearing &Grading Development Standards -Appendix A2 Page 163
• The depth of the gravel should be at least 12 inches over the entire
inlet opening and extend at least 18 inches on all sides.
Cacchbasin Filters - Inserts should be designed by the manufacturer for
use at construction sites. The limited sediment storage capacity increases
the amount of inspection and maintenance required, which may be daily
for heavy sediment loads. The maintenance requirements can be reduced
by combining a catchbasin filter with another type of inlet protection.
This type of inlet protection provides flow bypass without overflow and
therefore may be a better method for inlets located along active rights -of -
way.
• 5 cubic feet of storage.
• Dewatering provisions.
• High -flow bypass that will not clog under normal use at a construction
site.
• The catchbasin filter is inserted in the catchbasin just below the
grating.
Curb Inlet Protection with Wooden Weir — Barrier formed around a curb
inlet with a wooden frame and gravel.
• Wire mesh with'/2-inch openings.
• Extra strength filter cloth.
• Construct a frame.
• Attach the wire and filter fabric to the frame.
• Pile coarse washed aggregate against wire/fabric.
• Place weight on frame anchors.
Block and Gravel Curb Inlet Protection — Barrier formed around an inlet
with concrete blocks and gravel. See Figure 4.14.
• Wire mesh with'/2-inch openings.
• Place two concrete blocks on their sides abutting the curb at either side
of the inlet opening. These are spacer blocks.
• Place a 2x4 stud through the outer holes of each spacer block to align
the front blocks.
• Place blocks on their sides across the front of the inlet and abutting the
spacer blocks.
• Place wire mesh over the outside vertical face.
• Pile coarse aggregate against the wire to the top of the barrier.
Curb and Gutter Sediment Barrier — Sandbag or rock berm (riprap and
aggregate) 3 feet high and 3 feet wide in a horseshoe shape. See Figure
4.16.
• Construct a horseshoe shaped berm, faced with coarse aggregate if
Clearing & Grading Development Standards — Appendix A2 Page 164
using riprap, 3 feet high and 3 feet wide, at least 2 feet from the inlet.
• Construct a horseshoe shaped sedimentation trap on the outside of the
berm sized to sediment trap standards for protecting a culvert inlet.
Maintenance Catch basin filters should be inspected frequently, especially after
Standards storm events. If the insert becomes clogged, it should be cleaned or
replaced.
• For systems using stone filters: If the stone filter becomes clogged
with sediment, the stones must be pulled away from the inlet and
cleaned or replaced. Since cleaning of gravel at a construction site
may be difficult, an alternative approach would be to use the clogged
stone as fill and put fresh stone around the inlet.
• Do not wash sediment into storm drains while cleaning. Spread all
excavated material evenly over the surrounding land area or stockpile
and stabilize as appropriate.
Clearing & Grading Development Standards — Appendix A2 Page 165
Plan View
Back of Sidewalk A Catch Basin
2x4 Wood Stud
Back of Curb Concrete Block
Curb Inlet
ff
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�o00
�J
Wire Screen r
Filter Fabric Concrete Block
Section A — A ( Drain Gravel
20mm)
1/4" Drain Gravel
(20mm)
Pending Height
Concrete Block
Overflow
Ej
Curb Inlet X//
Wire Screen or
Filter Fabric
\ Catch Basin \\'
4 Wood Stud
(100x50 Timber Stud) \,
NOTES:
1. Use block and gravel type sediment barrier when curb inlet is located in gently sloping street segment,
where water can pond and allow sediment to separate from runoff.
2. Barrier shall allow for overflow from severe storm event.
3. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed
from the traveled way immediately.
Figure 4.15 — Block and Gravel Curb Inlet Protection
Clearing & Grading Development Standards — Appendix A2 Page 166
Plan View
Back of Sidewalk
NOTES:
1. Place curb type sediment barriers on gently sloping street segments, where water can pond and allow
sediment to separate from runoff.
2. Sandbags of either burlap or woven 'geotextile' fabric, are filled with gravel, layered and packed tightly.
3. Leave a one sandbag gap in the top row to provide a spillway for overflow.
4. Inspect barriers and remove sediment after each storm event. Sediment and gravel must be removed from
the traveled way immediately.
Figure 4.16 — Curb and Gutter Barrier
Clearing & Grading Development Standards — Appendix A2 Page 167
BMP C103: High Visibility Plastic or Metal Fence
Purpose Fencing is intended to: (1) restrict clearing to approved limits; (2) prevent
disturbance of sensitive areas, their buffers, and other areas required to be
left undisturbed; (3) limit construction traffic to designated construction
entrances or roads; and, (4) protect areas where marking with survey tape
may not provide adequate protection.
Conditions of Use To establish clearing limits, plastic or metal fence may be used:
• At the boundary of sensitive areas, their buffers, and other areas
required to be left uncleared.
• As necessary to control vehicle access to and on the site.
Design and High visibility plastic fence shall be composed of a high -density
Installation polyethylene material and shall be at least four feet in height. Posts
Specifications for the fencing shall be steel or wood and placed every 6 feet on
center (maximum) or as needed to ensure rigidity. The fencing shall
be fastened to the post every six inches with a polyethylene tie. On
long continuous lengths of fencing, a tension wire or rope shall be
used as a top stringer to prevent sagging between posts. The fence
color shall be high visibility orange. The fence tensile strength shall
be 360 lbs./ft. using the ASTM D4595 testing method.
• Metal fences shall be designed and installed according to the
manufacturer's specifications.
• Metal fences shall be at least 3 feet high and must be highly visible.
• Fences shall not be wired or stapled to trees.
Maintenance If the fence has been damaged or visibility reduced, it shall be
Standards repaired or replaced immediately and visibility restored.
Clearing & Grading Development Standards Page 84