HomeMy WebLinkAboutBLD2006-00411 - Stormwater Management tormwater
Management
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Owners:
Jody and Rod Mager L. ,i Vi=�.6Pi.iENT
PERMIT # KO _.
Location:
0 6 - 0 4 11 649 Sugar Hill Road
Chimacum, WA 98325
JEFFERSON COUNTY OCU w .
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EXPIRES 05/05/0
APPROVED
Prepared by: $TORMWATER PLAN
Laura Parsons, P.E.
Brostrom Engineering, PLLC AUG 1 7 2006
922 '/2 Washington Street, #6
Port Townsend, WA 98368 JEFFER co TY
Phone & Fax: (360)-379-6402 DEPT.OF i
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Email: laurabparsons@hotmail.com SIGNATUR.. 1II I.,!: 1,A
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July 12, 2006
Brostrom Engineering, PLLC Job No: 06025
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Table of Contents
SECTION 1: INTRODUCTION 3
1.1 PROJECT DESCRIPTION 3
1.2 PROJECT CLASSIFICATION 3
1.3 STORMWATER MANAGEMENT PLAN OVERVIEW 3
SECTION 2: STORMWATER SITE PLAN 5
2.1 STEP 1: COLLECT AND ANALYZE INFORMATION ON EXISTING CONDITIONS 5
2.2 STEP 2: PREPARE PRELIMINARY DEVELOPMENT LAYOUT 6
2.3 STEP 3: PERFORM AN OFF—SITE ANALYSIS 7
2.4 STEP 4: REVIEW THE APPLICABLE MINIMUM REQUIREMENTS 7
2.5 STEP 5: PREPARE A PERMANENT STORMWATER CONTROL PLAN 7
2.6 STEP 6:PREPARE A CONSTRUCTION STORMWATER POLLUTION PREVENTION PLAN
(SWPPP) 8
2.7 STEP 7: COMPLETE THE STORMWATER SITE PLAN 8
2.8 STEP 8: CHECK COMPLIANCE WITH ALL APPLICABLE MINIMUM REQUIREMENTS 9
SECTION 3: CONSTRUCTION STORMWATER POLLUTION PREVENTION 10
ELEMENT 1: MARK CLEARING LIMITS 10
ELEMENT 2: ESTABLISH CONSTRUCTION ACCESS 10
ELEMENT 3: CONTROL FLOW RATES 10
ELEMENT 4: INSTALL SEDIMENT CONTROLS 11
ELEMENT 5: STABILIZE SOILS 11
ELEMENT 6: PROTECT SLOPES 11
ELEMENT 7: PROTECT DRAIN INLETS 11
ELEMENT 8: STABILIZE CHANNELS AND OUTLETS 11
ELEMENT 9: CONTROL POLLUTANTS 12
ELEMENT 10: CONTROL DE—WATERING 12
ELEMENT 11: MAINTAIN BEST MANAGEMENT PRACTICES(BMPS) 12
ELEMENT 12: MANAGE THE PROJECT 12
SECTION 4: SOURCE CONTROL OF POLLUTION 14
SECTION 5: PRESERVATION OF NATURAL DRAINAGE SYSTEMS AND
OUTFALLS 15
SECTION 6: ON—SITE STORMWATER MANAGEMENT 16
APPENDICES — 18 --- —
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JUL �.
Page 2 of 18
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Section 1: Introduction
1.1 Project Description
This stormwater management plan is being presented to the Jefferson County Department
of Community Development as part of the building permit application requirements for
the proposed Mager Residence at 649 Sugar Hill Road in Chimacum, Washington.
The Mager Residence Project includes the construction of a 1684 square foot house and
the installation/extension of water/sewer/stormwater/driveway infrastructure for the new
building. A studio with two bedrooms and a bath was previously constructed on the
property and temporarily serves as a home for the owners. Due to the current occupancy
of the studio, a well and septic system were previously installed. Both the well and septic
system have sufficient capacity to provide water and sewer service to the new house and
the existing studio. Upon completion of the project, the studio will be converted to an
office space upstairs with two guest rooms and a bathroom downstairs.
1.2 Project Classification
Jefferson County categorizes all new development or re-development projects as small,
medium or large. In context of this stormwater management plan, the Mager Residence
Project shall be classified as a New Development "Medium" Project. The stormwater
calculation worksheet, located in Appendix A, was used to determine this classification.
The stormwater calculation worksheet identifies six components which are used to
determine the classification:
1) Parcel Size
2) Land Disturbing Activities
3) Conversion of Native Vegetation
4) Volume of Cut/Fill
5) Total New Impervious Surfaces
6) Total Existing Impervious Surfaces
This project creates less than 5000 square feet of new impervious surfaces, and this is the
primary reason that this project falls into the category of "Medium". A table which
indicates the amounts of impervious/pervious surfaces is included in the stormwater
calculation worksheet (see Appendix A). The new and existing surfaces are also shown
on the accompanying Site Coverage Plan.
1.3 Stormwater Management Plan Overview
This stormwater management plan has been prepared primarily based on the Washington
Department of Ecology 2001 Edition of the Stormwater Management Manual for
Western Washington (called "The Manual" hereafter in this report). Jefferson County
adopted the 2001 Edition in December 2002. In February 2005, a new edition of The
Manual was issued by the Department of Ecology, and although the County has not yet
Page 3 of 18
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Section 2: Stormwater Site Plan
Section 2 satisfies The Manual's Minimum Requirement #1, Preparation of a Stormwater
Site Plan. This section provides the stormwater site plan information in a step-by-step
format, as outlined in The Manual. The format consists of eight steps, which when fully
addressed, result in a stormwater site plan.
2.1 Step 1: Collect and Analyze Information on Existing Conditions
Step One requires that the existing site conditions be reviewed. This includes describing
the existing topography, any critical areas, existing development, existing stormwater
facilities, existing vegetation, and soils. Following these descriptions, the site's
limitations (in terms of stormwater management) are identified.
Existing Topography
The Mager Residence Project is located on a hilltop area, with access provided by Sugar
Hill Road, in the region of Chimacum. The project is located on a parcel that is 5.01
acres, with the east/west property lines extending approximately 1514 feet and the
north/south property lines extending approximately 155 feet. The west portion of the
property slopes downward toward Beaver Valley Road. From the top of bank to the west
property line, the elevation change is approximately 170 feet. A 15 foot building setback
from the top of bank has been identified by Jefferson County. The building site itself is
mostly level and at an elevation of approximately 400-415 feet. To the east of the
building site, the property slopes gradually downward toward Sugar Hill Road and
beyond to the east property line, which is at an approximate elevation of 320 feet.
Critical Area
The west portion of the property from the top of bank to the west property line has been
classified by Jefferson County as an environmentally sensitive area. This area is
categorized as having a "Moderate" landslide hazard. Because of this classification, the
area has been left undisturbed. The area is also heavily vegetated, which helps maintain
stability of the slope. There is no intent, as part of this project, to direct any stormwater
whatsoever over the top of the bank into the critical area. All stormwater will be directed •
to the east.
Existing Development
As elaborated on in the project description, a studio with two bedrooms and a bath was
previously constructed on the property and temporarily serves as a home for the owners.
Due to the current occupancy of the studio, a well and septic system were previously
installed. Both the well and septic system have sufficient capacity to provide water and
sewer service to the new home and the existing studio.
Existing Stormwater Facilities
The recently constructed studio has its downspouts and footing drain tied into two 4"
PVC . . ... .. . .....
pipes. These pipes extend from the northeast corner of the building along the west
side of a curtain drain. This curtain drain intercepts surface flow running'.down the slope -
Page 5 of 18
s
development to the west. And there is no proposed development of the site east of Sugar
Hill Road. Out of the parcel's 5.01 acres, 4.03 acres will be left undeveloped.
2.3 Step 3: Perform an Off-Site Analysis
Step Three is for "Large" projects. This step is directed toward projects which add 5,000
square feet or more of new impervious surface, or that convert 3/4 acres of pervious
surfaces to lawn or landscaped areas, or convert 2.5 acres of forested area to pasture. The
Mager Residence Project is a "Medium" project, and thus this report does not need to
address Step 3.
2.4 Step 4: Review the Applicable Minimum Requirements
Step Four requires that the applicable minimum requirements are reviewed. This review
was previously completed in "Section 1.3 Stormwater Management Plan Overview"
above. Sections 2 through 6 of this report address each of The Manual's minimum
requirements.
2.5 Step 5: Prepare a Permanent Stormwater Control Plan
Step Five requires that stormwater control facilities and Best Management Practices
(BMPs) are selected. BMP options have been identified and numbered by the
Department of Ecology in The Manual. The process for selecting BMPs is part of
Requirement #6 of The Manual. Because this project is "Medium" in size, Requirement
#6 does not apply. Therefore the selection of BMPs as described under Requirement #6
was not used to complete this report. However, other BMPs will be applied to this
project. BMPs are referenced throughout this document in the sections where they are
relevant. All BMPs which apply to this project are included in Appendix C. In reference
to Step Five, after the BMPs are selected, then the following six sections should be
addressed:
Permanent Stormwater Control Plan—Existing Site Hydrology
The existing hydrology has been basically indicated above. In review, the site is at the
top of a hill, so the only stormwater it will receive is from rainfall. The majority of the
site slopes to the east, away from the top of bank which marks the east boundary of the
landslide hazard zone. There are no known natural streams or drainage features on the
property. In the site's predevelopment state, all rainfall was either absorbed by the
vegetation and other permeable terrain features or sheet-flowed off the site.
Permanent Stormwater Control Plan—Developed Site Hydrology
The developed site hydrology has been basically indicated above. In review, all rainfall
to be intercepted by the roof structures will be directed to downspouts and through 4-inch
PVC pipes to a discharge point on the east side of the property. All other impervious
surface runoff will sheet-flow into the surrounding landscaping and away from all
structures. Surface water which flows in the direction of the septic system's drainfield
will be intercepted by a curtain drain and directed around the drainfield to a location at
the east end of the property. 80% of the site will remain completely undeveloped .and,
this portion will continue to behave hydrologically as in the parcel's pre-development
state.
Page 7of18
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Permanent Stormwater Control Plan
The information required regarding a permanent stormwater control plan can be found
above in Section 2.5 - Step 5: Prepare a Permanent Stormwater Control Plan
Special Reports and Studies
A copy of the soils analysis (by Charles Pollmar, described in 2.1 Step 1: Collect and
Analyze Information on Existing Conditions) has been included in this report in
Appendix B. A copy of the Jefferson County printout, depicting the landslide hazard
zone is also attached. (See Appendix D.) Two geotechnical reports were generated about
the subdivision where the Mager Residence Project is located. The report dated
November 8, 2002 recommended that stormwater generated on-site should be directed to
the east, as is proposed in this project. The geotechnical report dated February 1996
states that footing drains and roof drains should be kept separate, again, as proposed in
this project. Beyond these documents, no other special reports or studies related to the
stormwater management were generated for this project.
Other Permits
There are no other permits for this project which include stormwater management
conditions.
Operations and Maintenance Manual
An operations and maintenance manual is required for projects which include flow
control and treatment facilities. None of the BMPs related to this project have any
maintenance requirements to summarize in a manual. All BMPs listed for this project are
included in Appendix C.
Bond Quantities Worksheet
There is no bond information pertinent to this project.
2.8 Step 8: Check Compliance with all Applicable Minimum Requirements
Per Step Eight, the stormwater site plan as designed and implemented, should specifically
fulfill all minimum requirements applicable to the project. This project is a medium size
project, so the first five minimum requirements of The Manual apply. In reviewing the
stormwater management plan as a whole, all five minimum requirements have been
addressed. These five minimum requirements are listed above in Section 1.3 -
Stormwater Management Plan Overview.
Jefferson County also provides a Stormwater Site Plan Template which can be used in
lieu of generating a report (for "Medium" projects). A copy of this template has been
filled out and signed by the owner. It references sections in this report. The copy is
included in Appendix E.
Page 9 of 18
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Element 4: Install Sediment Controls
Prior to leaving a construction site, stormwater runoff from disturbed areas shall pass
through appropriate sediment removal structures. These structures are identified in The
Manual as Best Management Practices (BMPs). For the Mager Residence Project, a straw
bale barrier, a brush barrier, or silt fence can be installed in order to provide sediment
control. These options are applicable because the drainage area is small, and all
construction stormwater runoff will be overland flows. These sediment controls would
not be appropriate if they were to treat concentrated flows. Any of the three sediment
control methods should be placed downslope of all disturbed areas. Refer to BMP C230—
Straw Bale Barrier, BMP C231 — Brush Barrier, BMP C233 - Silt Fences for additional
details. These details are shown in Appendix C.
Element 5: Stabilize Soils
In order to minimize sediment leaving the construction site via runoff, various soil
stabilization practices may be implemented for all exposed and unworked soils. Jefferson
County recommends several BMPs for stabilizing soils that may be applicable to
different types of construction sites. The BMPs most applicable to the Mager Residence
Project are mulching (BMP C121), and plastic coverings (BMP C123). The mulching
should be used on any disturbed area not to receive vehicular traffic. Plastic covers
should be used on any soils which are stockpiled on the site. Dust control methods
(BMP C 140) are recommended during the dry season. For more detailed information
about each of these BMPs, see Appendix C.
Element 6: Protect Slopes
Element 6 applies to slopes which are 3:1 (horizontal:vertical) or 33%, or.greater. There
are no slopes within the building site which are 33% or more. Therefore, Element 6 does
not apply to this project.
Element 7: Protect Drain Inlets
Element 7 applies to urban construction sites. This project site is located in a rural area.
Surrounding parcels are approximately 5 acres in size. Therefore Element 7 does not
apply to this project.
Element 8: Stabilize Channels and Outlets
It is important to protect pipe outlets in order to minimize erosion. This is done by
reducing the velocity of concentrated stormwater flows. This project's outlet pipes for
the downspouts, footing drains, and curtain drain are all located in the same area.
Currently they discharge to a heavily vegetated area. There are no visible signs of
erosion. Jefferson County recommends using BMP C209 — Outlet Protection when
specifying details for outlet protection. (See Appendix C for details.) For the Mager
Residence Project, the outlet pipes all have a slope of less than one percent at the outfall.
For this type of slope, BMP C209 specifies outlet protection using 2-inch to 8-inch
riprap, a minimum of one foot thick. The Manual alternatively recommends using a rock
lining (per Table 4.4, Vol. V) which is one foot thick. Figure 4.7 in The Manual provides
Pagel 1 of 18
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As part of phasing the project, revegetation of the site is also intended. Revegetation will
enhance soil stabilization.
Season Work Limitations
Because it is the intent of this project to infiltrate all stormwater flows on-site, seasonal
work limitations need not apply. As well, sediment control BMPs, such as strawbale
barriers, branch barriers or silt fences, are to be employed on this project, thus allowing
for more flexibility of the seasons when construction can occur. (See Element 4 and
Appendix C for more details.) Furthermore, this project is surrounded by heavily
vegetated areas, with no signs of active erosion, which also suggests that construction
could occur at any time of the year.
Coordination with Utilities
The stormwater management system for this project site will have minimal complexity.
Due to the system's overall simplicity, very little coordination with utilities will be
necessary. Regarding stormwater, the primary responsibility of the construction
contractor will be to closely follow the stormwater management requirements indicated
on the plans and in this report. It will also be the responsibility of the contractor to select
one of the three identified sediment control BMPs that will be most compatible with their
operations and installation capacity.
Inspecting and Monitoring
As discussed in Element 11, all BMPs shall be inspected, maintained, and repaired as
needed during the construction process. This inspection and monitoring is important in
order to ensure that the BMPs don't fail unexpectedly. In the case of sediment control
BMPs, failure could mean suddenly discharging water and sediment that was previously
trapped and contained by the structure.
Page 13 of 18
0 !
Section 5: Preservation of Natural Drainage Systems and Outfalls
Section 5 satisfies The Manual's Minimum Requirement #4, Preservation of Natural
Drainage Systems and Outfalls. This section reviews the effects of this project on natural
systems and outfalls. For any project, it is preferable to maintain natural drainage
patterns, and discharge from the project shall occur at a natural location. It is also
important that discharged runoff does not cause significant adverse impacts to
downstream waters or surrounding properties. All outfalls require energy dissipation.
As described above, the Mager Residence Project is located at the top of a hill. In the
site's pre-development state, stormwater fell directly on the area, and sheet flowed away
from the high point, primarily toward the east. The intent of the project is to continue
directing stormwater east through the drainage system. All downspouts, footing drains,
and a curtain drain which protects the septic system drainfield will be directed to a
densely vegetated area and be allowed to disperse/infiltrate naturally from that point. (See
Fig. 4.7 in Appendix C for construction specifications.)
Page 15 of 18
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Outfall Protection
The downspout and foundation drains, as well as the curtain drains, are all discharged at
locations next to each other. (See project plans.) This location will have a rock layer
installed which will be large enough to dissipate the energy from all three flows. The
rock area will generally follow the configuration shown in Figure 4.7. Figure 4.7 is
located in Appendix C and comes from Vol. 5, Chapter 4,pg. 4-24 of The 2005 Manual.
Swale:
Beyond the outfall protection area, a small vegetated swale will be constructed, to further
dissipate the concentrated flow, before it sheet-flows into the heavily vegetated
surrounding area. The swale should be constructed per BMP C200 — Interceptor Dike
and Swale. A copy of this BMP can be found in Appendix C.
Page 17of18
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APPENDICES
Appendix A — Stormwater Calculation Worksheet
Appendix B — Soil Log Analysis
Appendix C —Best Management Practices (BMPs)
Appendix D — Jefferson County Landslide Information
Appendix E — Stormwater Site Plan Template
Appendix F — Permeable Surfacing and Catch Basin Detail
Page18of18
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Appendix A
Stormwater Calculation Worksheet
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�?i 1 JEFFERSON COUNTY
DEPARTMENT OF', COMMUNITY DEVELOPMENT
:.,> + 621 Sheridan Street-Port Townsend-Washington98368
1%.114120 . 360/379-4450 .360y379-4.451 Fax
http://www.cojefferson.wa.us/comrridevelopment/
Stormwater Calculation Work:sheet
Pi IEcr/AppticAurMIME: -3'01a MAC V PS, CnJce
DETERMINING STORMWATER MANAGEMENT QIREMENTS:This
stormwater calculation or eet should be
with ato fy the sal as I, 'Medium,'
nedkum,'perr ' The size determines whether a Stormwater Site Plan is required completed first
with
a stand-alonea review. The mabanagement
•baling permit app6�rr,or other land use
information approval apptication*II also be helpful for completing a Site that.
PARCEL SIZE 11.F,,_Sr
Size of parcel S• 2 L acres An acre contains 43,560
square feet. Multiply the acreage by this figure.
Size of parcel in square feet ..2. 8 2 3 scy'ft
Lan dim is any Y that result in movement of
non-vegetative)and/or the existing sal ,or a change in the enot li soil oar , are,
excavation,and compaction associated with of and
construction.are qt d to clearing, grddng, s
structures Bing,
Native vegetation is Vega wised on plant species,other than noxious Pacific Northwest and which reasonably could have beenweeds,that are to the coastal region of as
Douglas fir,western hemlock,western red alder expected to naturally occur on the site. Examples include species such as
and said!:herbaceous plants such as sword cedar,fern foam flower,and 1-leaf i maple;shrubs such as willow,sldetbenY.sahnonberrY,
LAND DISTURBING ACTIVITY,CONVERSION OF NATIVE VEGETATION,AND VOLUME OF CUT/FILL
Calculate the total area to be cleared,graded,fled,
excavated,and/or compacted for proposed developmentconversion
o e n er the ffpowve two questions related to
project. Include in this calculation the area to be cleared tar sion of nati►n vegetation:
Constructionsite for structures Z�� O Does the projectconvert%acres or more of
scyft native vegetation to lawn or landscaped areas?
D rainfield,septic tank,etc. sgrit Circle: Yes 0
Well,utats,etc.
Does the project convert 2 3c acres or more of
Driveway,parking,etc. o't,(„5® sent
native vegetation to pasture?
Lawn,landscaping,etc. 32.7 0 Ci : Yes
Other compacted surface,etc. l n sq/It Indicate Total Volumes of Proposed:
Total Land Disturbancecif G S o
sqat Cut (03 _fill--.7 __.___,-_-.
•
v
[over]
1
!mpervfous surface is a hard surface that either prevents or retards the entry of water into the soil mantle as under natural conditions
prior to development. A hard surface area which causes water to run off the surface in greater quantities or at an increased rate of flow
from the flow present under natural conditions prior to development. Common impervious surfaces include,but are not limited to.Teo
tops, walkways, patios,driveways, parking lots or storage areas,concrete or asphalt paving, gravel roads, packed earthen materials,
and oiled,macadam or other surfaces which similarly impede the natural infiltration of stormwater.
STORMWATER CALULATIONS—IMPERVIOUS SURFACE
NEW EXISTING
Structures(all roof area) 24 S Cc sq/ft Structures(all roof area) i C J7 sq/ft
Sidewalks 17 3 tc sq/ft Sidewalks
Patios 3 G& sq/ft Patios . sq/ft
Solid Decks sq/ft Solid Decks
_.(without infiltration below) (without infiltration below)
Driveway sq/ft Driveway 2 3 14 sq/It
Other sq/ft Other (01(4t;e1 roxis) 34 6
Total New E5 CDC sq/ft Total Existing 7 C 2 stet
TOTAL NEW+TOTAL EXISTING' i i . 5 i-)1 sq/ft This amount will be used to check total lot coverage.
The following questions will help determine whether the proposed project is considered development or redevelopment.
DEVELOPMENT v.REDEVELOPMENT
..,, -:_ a he•total;exsting;inpervious surface above by the size of the parcel and convert to a percentage: 3•2 %
Does the site have 35%or more of existing impervious surface? Circle: Yes
•
FURTHER INSTRUCTIONS: If the answer is yes, the proposal is considered redevelopment and the attached Figure 2 should be
used to determine the applicable Minimum Requirements. If the answer is no,the proposal is considered new development and the
attached Figure 1 should be used. At this juncture,the applicant should refer to the applicable Flow Chart to determine the Minimum
Requirements for stormwater management. DCD staff will help verify the classification of the project and the application requirements.
For proponents of "small" projects who must comply only with Minimum Requirement..#2—Construction Stormwater Pollution
Prevention—an additional submittal is not required. The proponent is responsible for employing the 12 Elements to control erosionlind
prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the Construction
Stormwater Pollution Prevention(SWPP) Best Management Practices (BMPs) Packet. Proponents of"medium"projects—those
that must meet only Minimum Requirements #1 through #5—and for large" projects—those that must meet all 10 Minimum
Requirements—are required to submit a Stormwater Site Plan. DCD has prepared a submittal template of a Stormwater Site Plan,
principally for rural residential projects. Complete the template in the Stormwater Site Plan Instructions and Submittal Template or
prepare a Stormwater Site Plan using the step-by-step guidance in the Stormwater Management Manual.
APPLICANT SIGNATURE
By signing the Stormwater Calculation Worksheet, I as the applicant/owner attest that the information provided herein is true and
correct to the best of my knowledge. I also certify that this application is being made with the full knowledge and consent of all
owners of the affected property.
•
to/A - ----
(LANDOWNER 09kUTHORIZED REPRESENTATIVE SIGNATURE) •
•
stormwater cats wodcshee t—REV.10112003 2
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FIGURE 1: NEW DEVELOPMENT
Start Here
i -
Does the site have Yes See Redevelopment
35%or more of
existing impervious
coverage? Requirements and
Flow Chart
o Does the project convert 34 �i 2)
acres or more of native
vegetation to lawn or
Does the project add 4 o) landscaped areas,or
5,000 square feet or convert 2.5 acres or more
more of new of native vegetation to
impervious surfaces?
pasture?
Yes IA Yes
\No
Does the project have
7 1 "LARGE"PROJECT 2,000 square feet or
All Minimum Requirements more of new,replaced,
IN*
to tl anew mpervi us
pervious surfaces. - __- -- - or-new-plus-replaced _--.
surfaces and converted impervious surfaces?
CfeyN®
= . "MEDIUM"PROJECTes the project have
Minimum Requirements#1 land-disturbing
through#5 apply to the new 4 es activities of 7,000
and replaced impervious square feet or more?
surfaces and the land
disturbed. No
- - "SMALL"PROJECT _
•
See Minimum
Requirement#2,
Construction Stormwater
Pollution Prevention
1
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Appendix B
Soil Log Analysis
II
rAKUtL IF 3(.11-1.55 IS Client: MAGER
SOIL AND SITE INFORMATION
SOIL LOG ANALYSIS
SOIL LOG# I SOIL TYPE: 4 APPLICATION RATE: 60 ROOTS TO: 48„
DEPTH 0-18"± LOOSE, DARK BROWN, SANDY LOAM TOPSOIL
18-48" LOOSE, TAN, FINE GRAIN, SILTY, SANDY LOAM SUBSOIL
a 48" COMPACTED, HEAVILY MOTTLED, FINE SANDS & SILTS
SOIL LOG#2 SOIL TYPE: 4 . APPLICATION RATE: .60 ROOTS TO: 38„+
PTH DE 0-12" BROWN, SANDY, TOPSOIL
12-52" LOOSE TO- FAIRLY LOOSE, LIGHT BROWN, FINE GRAIN, SANDY LO
& FINE GRAIN, SAND - BECOMING SOMEWHAT MORE SILTY & TIGHT
52-60"+ . . SEMI-COMPACTED, HEAVILY MOTTLED, SILTS/SANDS W/DEPTH`
SOIL LOG#3 SOIL TYPE:4 APPLICATION RATE: .60 ROOTS TO: 38"
DEPTH 0-38" LOOSE, DARK BROWN, SANDY, TOPSOIL & DARK BROWN TO BROWN, .
MEDIUM TO -FINE GRAIN, SANDY LOAM
38-42"+ COMPACTED, MOTTLED, LIGHT BROWN, LIGHTLY CEMENTED, SAND i
W/SILTS !
SOIL LOG## SOIL TYPE: 4 APPLICATION RATE: .60 ROOTS TO: - 39"+
DEPTH -0-13" DARK BROWN, SANDY, TOPSOIL
13-28" FAIRLY LOOSE, FINE GRAIN, TAN, SANDY LOAM
28-35" LOOSE, LIGHT BROWN, FINE GRAIN, LOAMY SAND W/ROCKS
35-39" COMPACTED, MOTTLED, TAN, SAND W/ROOT PENETRATION THROUGH
BOTTOM OF HOLE
SOIL.LOG#5 SOIL TYPE APPLICATION RATE: .60 ROOTS TO 38"
DEPTH 0-8" DARK BROWN, SANDY, TOPSOIL
8-38�. LOOSE TO FAIRLY LOOSE, FINE GRAIN, TAN, � i
SANDY. LOAM r �
38-42"+ COMPACTED, TAN, SILTY SAND W/MOTTLING - #'frsS/
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f r 11 le
4
i•= 5100203 - '".�
ADDITIONAL INFORMATION " -: +14.43 ��
WELLS OR SURFACE WATER
DEPTH O WIIN'H0F1OOF N.CH N 0NATIVE DISTANCE
MAXIMUM OR PROPOSED TREN IN SOIL= IN. asvxED TO TRE�resBorrom)
REQUIRED BOTTOM ABSORPTION AREA= -ion* sq.fL LINEAL YE OF TRENCH REQUIRED: 100*
METHOD OF ON-SITE E SEWAGE DISPOSAL SYSTEM PROPOSED: *(W/50% REDUCTION FOR SAND
A.)XXX36 WIDE TRENCH B.) EXTRA GRAVEL DEPTH TRENCH C.) MOUND SYSTEM F I LTE
D.)XXXSAND FILTER PRE-TREATMENT E.) OTHER
XXX rye LINER/ CONCRETE RECEPTACLE)
METHOD OF DISTRIBUTION: D-BOX XXX SERIAL XXXXEQUAL(RRFSSURE DITRIBUTION)
COVER REQUIRED: YES DEPTH: 12" NATIVE SOIL SVTTABLL FORME AS-COVER? NO
FILL REQUIRED: NO . DEPTH: TYPE OF FILL MATERIA[. MEDIUM TO COARSE SAND ;_
DATETESTS CONDUCTED: 4/14, 4/28, 5/6, & 5/17/2005 At
• •
Appendix C
Best Management Practices (BMPs)
BMP C 101 — Preserving Natural Vegetation
BMP C 102 — Buffer Zone
BMP C 120 — Temporary and Permanent Seeding
BMP C121 — Mulching
BMP C123 — Plastic Covering
BMP C140 — Dust Control
BMP C 151 — Concrete Handling
BMP C162 — Scheduling
BMP C200 — Interceptor Dike and Swale
BMP C209 — Outlet Protection
Table 4.4 — Rock Protection at Outfalls
Figure 4.7 — Pipe Outfall Discharge Protection
BMP C230 — Straw Bale Barrier
BMP C231 — Brush Barrier
BMP C233 — Silt Fence
BMP T5.10 — Downspouts
• 4110
4.1 Source Control BMPs
BMP C101: Preserving Natural Vegetation
Purpose The purpose of preserving natural vegetation is to reduce erosion wherever
practicable. Limiting site disturbance is the single most effective method
for reducing erosion. For example, conifers can hold up to about 50
percent of all rain that falls during a storm. Up to 20-30 percent of this rain
may never reach the ground but is taken up by the tree or evaporates.
Another benefit is that the rain held in the tree can be released slowly to the
ground after the storm.
Conditions of Use • Natural vegetation should be preserved on steep slopes, near
perennial and intermittent watercourses or swales, and on building
sites in wooded areas.
• As required by local governments.
Design and Natural vegetation can be preserved in natural clumps or as individual
Installation trees, shrubs and vines.
Specifications
The preservation of individual plants is more difficult because heavy
equipment is generally used to remove unwanted vegetation. The points
to remember when attempting to save individual plants are:
• Is the plant worth saving? Consider the location, species, size,age,
vigor,and the work involved. Local governments may also have
ordinances to save natural vegetation and trees.
• Fence or clearly mark areas around trees that are to be saved. It is
preferable to keep ground disturbance away from the trees at least as
far out as the dripline.
Plants need protection from three kinds of injuries:
• Construction Equipment- This injury can be above or below the
ground level.`Damage results from scarring, cutting of roots, and
compaction of the soil. Placing a fenced buffer zone around plants to
be saved prior to construction can prevent construction equipment
injuries.
• Grade Changes- Changing the natural ground level will alter grades,
which affects the plant's ability to obtain the necessary air, water, and
minerals. Minor fills usually do not cause problems although
sensitivity between species does vary and should be checked. Trees
can tolerate fill of 6 inches or less. For shrubs and other plants, the fill
should be less.
When there are major changes in grade, it may become necessary to
supply air to the roots of plants. This can be done by placing a layer of
gravel and a tile system over the roots before the fill is made. A the
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• • •
Pacific dogwood, and Red alder can cause serious disease problems.
Disease can become established through damaged limbs, trunks, roots,
and freshly cut stumps. Diseased and weakened trees are also
susceptible to insect attack.
Maintenance • Inspect flagged and/or fenced areas regularly to make sure flagging or
Standards fencing has not been removed or damaged. If the flagging or fencing
has been damaged or visibility reduced, it shall be repaired or
replaced immediately and visibility restored.
• If tree roots have been exposed or injured, "prune" cleanly with an
appropriate pruning saw or lopers directly above the damaged roots
and recover with native soils. Treatment of sap flowing trees (fir,
hemlock, pine, soft maples) is not advised as sap forms a natural
healing barrier.
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BMP C102: Buffer Zones
Purpose An undisturbed area or strip of natural vegetation or an established
suitable planting that will provide a living filter to reduce soil erosion and
runoff velocities.
Conditions of Use Natural buffer zones are used along streams, wetlands and other bodies of
water that need protection from erosion and sedimentation. Vegetative
buffer zones can be used to protect natural swales and can be incorporated
into the natural landscaping of an area.
Critical-areas buffer zones should not be used as sediment treatment areas.
These areas shall remain completely undisturbed. The local permitting
authority may expand the buffer widths temporarily to allow the use of the
expanded area for removal of sediment.
Design and • Preserving natural vegetation or plantings in clumps, blocks, or strips
Installation is generally the easiest and most successful method.
Specifications • Leave all unstable steep slopes in natural vegetation.
• Mark clearing limits and keep all equipment and construction debris
out of the natural areas. Steel construction fencing is the most
effective method in protecting sensitive areas and buffers.
Alternatively, wire-backed silt fence on steel posts is marginally
effective. Flagging alone is typically not effective.
• Keep all excavations outside the dripline of trees and shrubs.
• Do not push debris or extra soil into the buffer zone area because it
will cause damage from burying and smothering.
• Vegetative buffer zones for streams, lakes or other waterways shall be
established by the local permitting authority or other state or federal
permits or approvals.
Maintenance • inspect the area frequently to make sure flagging remains in place
Standards and the area remains undisturbed.
February 2005 Volume II— Construction Storm water Pollution Prevention 4-5
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BMP C120: Temporary and Permanent Seeding
Purpose Seeding is intended to reduce erosion by stabilizing exposed soils. A
well-established vegetative cover is one of the most effective methods of
reducing erosion.
Conditions of Use • Seeding may be used throughout the project on disturbed areas that
have reached final grade or that will remain unworked for more than
30 days.
• Channels that will be vegetated should be installed before major
earthwork and hydroseeded with a Bonded Fiber-Matrix. The
vegetation should be well established (i.e., 75 percent cover) before
water is allowed to flow in the ditch. With channels that will have
high flows, erosion control blankets should be installed over the
hydroseed. If vegetation cannot be established from seed before water
is allowed in the ditch, sod should be installed in the bottom of the
ditch over hydrornulch and blankets.
• Retention/detention ponds should be seeded as required.
• Mulch is required at all times because it protects seeds from heat,
moisture loss,and transport due to runoff.
• All disturbed areas shall be reviewed in late August to early September
and all seeding should be completed by the end of September.
Otherwise, vegetation will not establish itself enough to provide more
than average protection.
• At final site stabilization, all disturbed areas not otherwise vegetated or
stabilized shall be seeded and mulched. Final stabilization means the
completion of all soil disturbing activities at the site and the
establishment of a permanent vegetative cover, or equivalent
permanent stabilization measures (such as pavement, riprap, gabions
or geotextiles) which will prevent erosion.
Design and • Seeding should be done during those seasons most conducive to
Installation growth and will vary with the climate conditions of the region.
Specifications Local experience should be used to determine the appropriate
seeding periods.
• The optimum seeding windows for western Washington are April 1
through June 30 and September 1 through October 1. Seeding that
occurs between July 1 and August 30 will require irrigation until 75
percent grass cover is established. Seeding that occurs between
October 1 and March 30 will require a mulch or plastic cover until
75 percent grass cover is established.
• To prevent seed from being washed away, confirm that all required
surface water control measures have been installed.
February 2005 Volume II-Construction Storm water Pollution Prevention 4=13
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• Mulch is always required for seeding. Mulch can be applied on top of
the seed or simultaneously by hydroseeding.
• On steep slopes, Bonded Fiber Matrix(BFM) or Mechanically Bonded
Fiber Matrix (MBFM) products should be used. BFM/MBFM
products are applied at a minimum rate of 3,000 pounds per acre of
mulch with approximately 10 percent tackifier. Application is made
so that a minimum of 95 percent soil coverage is achieved. Numerous
products are available commercially and should be installed per
manufacturer's instructions. Most products require 24-36 hours to
cure before a rainfall and cannot be installed on wet or saturated soils.
Generally, these products come in 40-50 pound bags and include all
necessary ingredients except for seed and fertilizer.
BFMs and MBFMs have some advantages over blankets:
• No surface preparation required;
• Can be installed via helicopter in remote areas;
• On slopes steeper than 2.5:1, blanket installers may need to be roped
and harnessed for safety;
• They are at least$1,000 per acre cheaper installed.
In most cases,the shear strength of blankets is not a factor when used on
slopes, only when used in channels. BFMs and MBFMs are good
alternatives to blankets in most situations where vegetation establishment
is the goal.
• When installing seed via hydroseeding operations, only about 1/3 of
the seed actually ends up in contact with the soil surface. This reduces
the ability to establish a good stand of grass quickly. One way to
overcome this is to increase seed quantities by up to 50 percent.
• Vegetation establishment can also be enhanced by dividing the
hydromulch operation into two phases:
1. Phase l- Install all seed and fertilizer with 25-30 percent mulch
and tackifier onto soil in the first lift;
2. Phase 2- Install the rest of the mulch and tackifier over the first lift.
An alternative is to install the mulch, seed, fertilizer, and tackifier in one
lift. Then, spread or blow straw over the top of the hydromulch at a rate of
about 800-1000 pounds per acre. Hold straw in place with a standard
tackifier. Both of these approaches will increase cost moderately but will
greatly improve and enhance vegetative establishment. The increased cost
may be offset by the reduced need for:
1. Irrigation
2. Reapplication of mulch
3. Repair of failed slope surfaces --
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February 2005 Volume II—Construction Stormwater Pollution Prevention 4-15
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Table 4.1 represents the standard mix for those areas where just a
temporary vegetative cover is required.
Table 4.1
Temporary Erosion Control Seed Mix
%Weight %Purity %Germination '
Chewings or annual blue grass 40 98 90
Festuca rubra var. commutata or Poa anna
Perennial rye- 50 98 90
Lolium perenne
Redtop or colonial bentgrass 5 92 85
Agrostis alba or Agrostis tenuis
White dutch clover 5 98 90
Trifolium repens
Table 4.2 provides just one recommended possibility for landscaping seed.
Table 4.2
Landscaping Seed Mix
\\-eight %Purity %Germination
Perennial rye blend 70 98 90
Lolium perenne
Chewings and red fescue blend 30 98 90
Festuca rubra var. commutata
or Festuca rubra
This turf seed mix in Table 4.3 is for dry situations where there is no need
for much water. The advantage is that this mix requires very little
maintenance.
Table 4.3
Low-Growing Turf Seed Mix
% Weight %Purity %Germination
Dwarf tall fescue(several varieties) 45 98 90
Festuca arundinacea var. _
Dwarf perennial rye(Barclay) 30 98 90
Lolium perenne var. barclay
Red fescue 20 98 90
Festuca rubra
Colonial bentgrass 5 98 90
Agrostis tenuis
'Cable 4.4 presents a mix recommended for bioswales and other
intermittently wet areas.
Table 4.4
Bioswale Seed Mix*
%Weight %Purity °A Germination
Tall or meadow fescue 75-80 98 90
Festuca arundinacea or Festuca elatior
Seaside/Creeping bentgrass 10-15 92 85
Agrostis palustris
Redtop bentgrass 5-I0 90 80
Agrostis alba or Agrostis gigantea
*Modified Briargreen, Inc. Hydroseeding Guide Wetlands Seed Mix
February 2005 Volume 11—Construction Stormwater Pollution Prevention -°I_ s 4 1 t"'
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• After adequate cover is achieved, any areas that experience erosion
shall be reseeded and protected by mulch. If the erosion problem is
drainage related, the problem shall be fixed and the eroded area
reseeded and protected by mulch.
• Seeded areas shall be supplied with adequate moisture, but not watered
to the extent that it causes runoff.
February 2005 Volume II—Construction Stormwater Pollution Prevention 4-19
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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.
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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.
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BMP C140: Dust Control
Purpose Dust control prevents wind transport of dust from disturbed soil surfaces
onto roadways, drainage ways,and surface waters.
Conditions of Use • In areas (including roadways) subject to surface and air movement of
dust where on-site and off-site impacts to roadways, drainage ways,or
surface waters are likely.
Design and • Vegetate or mulch areas that will not receive vehicle traffic. In areas
Installation where planting, mulching,or paving is impractical, apply gravel or
Specifications landscaping rock.
• Limit dust generation by clearing only those areas where immediate
activity will take place, leaving the remaining area(s) in the original
condition, if stable. Maintain the original ground cover as long as
practical.
• Construct natural or artificial windbreaks or windscreens. These may
be designed as enclosures for small dust sources.
• Sprinkle the site with water until surface is wet. Repeat as needed. To
prevent carryout of mud onto street, refer to Stabilized Construction
Entrance(BMP C105).
• Irrigation water can be used for dust control. Irrigation systems should
be installed as a first step on sites where dust control is a concern.
• Spray exposed soil areas with a dust palliative, following the
manufacturer's instructions and cautions regarding handling and
application. Used oil is prohibited from use as a dust suppressant.
Local governments may approve other dust palliatives such as calcium
chloride or PAM.
• PAM (BMP C126) added to water at a rate of 0.5 lbs. per 1,000
gallons of water per acre and applied from a water truck is more
effective than water alone. This is due to the increased infiltration of
water into the soil and reduced evaporation. In addition, small soil
particles are bonded together and are not as easily transported by wind.
Adding PAM may actually reduce the quantity of water needed for
dust control, especially in eastern Washington. Since the wholesale
cost of PAM is about $4.00 per pound, this is an extremely cost-
effective dust control method.
Techniques that can be used for unpaved roads and lots include:
• Lower speed limits. High vehicle speed increases the amount of dust
stirred up from unpaved roads and lots.
• Upgrade the road surface strength by improving particle size, shape,
and mineral types that make up the surface and base'materials: '
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BMP C151: Concrete Handling
Purpose Concrete work can generate process water and slurry that contain fine
particles and high pH, both of which can violate water quality standards in
the receiving water. This BMP is intended to minimize and eliminate
concrete process water and slurry from entering waters of the state.
Conditions of Use Any time concrete is used, these management practices shall be utilized.
Concrete construction projects include, but are not limited to, the
following:
• Curbs
• Sidewalks
• Roads
• Bridges
• Foundations
• Floors
• Runways
Design and • Concrete truck chutes, pumps, and internals shall be washed out only
Installation into formed areas awaiting installation of concrete or asphalt.
Specifications • Unused concrete remaining in the truck and pump shall be returned to
the originating batch plant for recycling.
• Hand tools including, but not limited to, screeds, shovels, rakes, floats,
and trowels shall be washed off only into formed areas awaiting
installation of concrete or asphalt.
• Equipment that cannot be easily moved, such as concrete pavers, shall
only be washed in areas that do not directly drain to natural or
constructed stormwater conveyances.
• Washdown from areas such as concrete aggregate driveways shall not
drain directly to natural or constructed stormwater conveyances.
• When no formed areas are available, washwater and leftover product
shall be contained in a lined container. Contained concrete shall be
disposed of in a manner that does not violate groundwater or surface
water quality standards.
Maintenance Containers shall be checked for holes in the liner daily during concrete
Standards pours and repaired the same day.
h its:
February 2005 Volume I!—Construction Stormwater Pollution Prevention 4-43
BMP C162: Scheduling
Purpose Sequencing a construction project reduces the amount and duration of soil
exposed to erosion by wind, rain, runoff, and vehicle tracking.
Conditions of Use The construction sequence schedule is an orderlylistingof all major q J
land-
disturbing activities together with the necessary erosion and sedimentation
control measures planned for the project. This type of schedule guides the
contractor on work to be done before other work is started so that serious
erosion and sedimentation problems can be avoided.
Following a specified work schedule that coordinates the timing of land-
disturbing activities and the installation of control measures is perhaps the
most cost-effective way of controlling erosion during construction. The
removal of surface ground cover leaves a site vulnerable to accelerated
erosion. Construction procedures that limit land clearing, provide timely
installation of erosion and sedimentation controls, and restore protective
cover quickly can significantly reduce the erosion potential of a site.
Design • Avoid rainy periods.
Considerations • Schedule projects to disturb only small portions of the site at any one
time. Complete grading as soon as possible. Immediately stabilize the
disturbed portion before grading the next portion. Practice staged
seeding in order to revegetate cut and fill slopes as the work
progresses.
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4.2 Runoff Conveyance and Treatment BMPs
BMP C200: Interceptor Dike and Swale
Purpose Provide a ridge of compacted soil, or a ridge with an upslope swale, at the
top or base of a disturbed slope or along the perimeter of a disturbed
construction area to convey stormwater. Use the dike and/or swale to
intercept the runoff from unprotected areas and direct it to areas where
erosion can be controlled. This can prevent storm runoff from entering the
work area or sediment-laden runoff from leaving the construction site.
Conditions of Use Where the runoff from an exposed site or disturbed slope must be conveyed
to an erosion control facility which can safely convey the stormwater.
• Locate upslope of a construction site to prevent runoff from entering
disturbed area.
• When placed horizontally across a disturbed slope, it reduces the
amount and velocity of runoff flowing down the slope.
• Locate downslope to collect runoff from a disturbed area and direct it
to a sediment basin.
Design and • Dike and/or swale and channel must be stabilized with temporary or
Installation permanent vegetation or other channel protection during construction.
Specifications . Channel requires a positive grade for drainage; steeper grades require
channel protection and check dams.
• Review construction for areas where overtopping may occur.
• Can be used at top of new fill before vegetation is established.
• May be used as a permanent diversion channel to carry the runoff.
• Sub-basin tributary area should be one acre or less.
• Design capacity for the peak flow from a 10-year, 24-hour storm,
assuming a Type IA rainfall distribution, for temporary facilities.
Alternatively, use 1.6 times the 10-year, 1-hour flow indicated by an
approved continuous runoff model. For facilities that will also serve
on a permanent basis, consult the local government's drainage
requirements.
Interceptor dikes shall meet the following criteria:
Top Width 2 feet minimum.
Height 1.5 feet minimum on berm.
Side Slope 2:1 or flatter.
Grade Depends on topography, however, dike system minimum is
0.5%, maximum is 1%.
Compaction Minimum of 90 percent ASTM D698 standard proctor.
February 2005 Volume 11—Construction Stormwater Pollution Prevention 4-57
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BMP C209: Outlet Protection
Purpose Outlet protection prevents scour at conveyance outlets and minimizes the
potential for downstream erosion by reducing the velocity of concentrated
stormwater flows.
Conditions of use Outlet protection is required at the outlets of all ponds, pipes,ditches, or
other conveyances,and where runoff is conveyed to a natural or manmade
drainage feature such as a stream, wetland, lake, or ditch.
Design and The receiving channel at the outlet of a culvert shall be protected from
Installation erosion by rock lining a minimum of 6 feet downstream and extending up
Specifications the channel sides a minimum of 1—foot above the maximum tailwater
elevation or 1-foot above the crown,whichever is higher. For large pipes
(more than 18 inches in diameter), the outlet protection lining of the
channel is lengthened to four times the diameter of the culvert.
• Standard wingwalls, and tapered outlets and paved channels should
also be considered when appropriate for permanent culvert outlet
protection. (See WSDOT Hydraulic Manual, available through
WSDOT Engineering Publications).
• Organic or synthetic erosion blankets, with or without vegetation, are
usually more effective than rock, cheaper, and easier to install.
Materials can be chosen using manufacturer product specifications.
ASTM test results are available for most products and the designer can
choose the correct material for the expected flow.
• With low flows, vegetation(including sod) can be effective.
• The following guidelines shall be used for riprap outlet protection:
1. If the discharge velocity at the outlet is less than 5 fps(pipe slope
less than 1 percent), use 2-inch to 8-inch riprap. Minimum
thickness is 1-foot.
2. For 5 to 10 fps discharge velocity at the outlet(pipe slope less than
3 percent), use 24-inch to 4-foot riprap. Minimum thickness is 2
feet.
3. For outlets at the base of steep slope pipes (pipe slope greater than
10 percent), an engineered energy dissipater shall be used.
• Filter fabric or erosion control blankets should always be used under
riprap to prevent scour and channel erosion.
• New pipe outfalls can provide an opportunity for low-cost fish habitat
improvements. For example, an alcove of low-velocity water can be
created by constructing the pipe outfall and associated energy
dissipater back from the stream edge and digging a channel, over-
widened to the upstream side, from the outfall. Overwintering juvenile
and migrating adult salmonids may use the alcove as shelter during
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Table 4.4—Rock Protection at Outfalls
Discharge Velocity Required Protection
at Design Flow in feet Minimum Dimensions
per second(fps) Type Thickness Width Length Height
8 feet or
4 x diameter,
Diameter whichever is Crown
0—5 Rock lining�'� 1 foot +6 feet greater + 1 foot
Diameter
+6 feet or 12 feet or
3 x diameter, 4 x diameter,
whichever is whichever is Crown
5+- 10 Riprap(2) 2 feet greater greater + 1 foot
Crown
10+-20 Gabion outfall As required As required As required + 1 foot
Engineered energy
20+ dissipater required
Footnotes:
(') Rock lining shall be quarry spalls with gradation as follows:
Passing 8-inch square sieve: 100%
Passing 3-inch square sieve: 40 to 60%maximum
Passing 3/4-inch square sieve: 0 to 10%maximum
(2) Riprap shall be reasonably well graded with gradation as follows:
Maximum stone size: 24 inches(nominal diameter)
Median stone size: 16 inches
Minimum stone size: 4 inches
Note:Riprap sizing governed by side slopes on outlet channel is assumed to be approximately 3:1.
Option A--Anchored Plate(Figure 4.3)
• An anchored plate flow spreader must be preceded by a sump having a
minimum depth of 8 inches and minimum width of 24 inches. If not
otherwise stabilized, the sump area must be lined to reduce erosion and
to provide energy dissipation.
• The top surface of the flow spreader plate must be level, projecting a
minimum of 2 inches above the ground surface of the water quality
facility, or V-notched with notches 6 to 10 inches on center and 1 to 6
inches deep (use shallower notches with closer spacing). Alternative
designs may also be used.
• A flow spreader plate must extend horizontally beyond the bottom
width of the facility to prevent water from eroding the side slope. The
horizontal extent should be such that the bank is protected for all flows
up to the 100-year flow or the maximum flow that will enter the Water
Quality(WQ)facility.
• Flow spreader plates must be securely fixed in place.
• Flow spreader plates may be made of either wood, metal, fiberglass
reinforced plastic,or other durable material. If wood,pressure treated
4 by 10-inch lumber or landscape timbers are acceptable.
• Anchor posts must be 4-inch square concrete, tubular stainless steel, or
other material resistant to decay.
February 2005 Volume V—Runoff Treatment BMPs 4-17
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BMP C230: Straw Bale Barrier
Purpose To decrease the velocity of sheet flows and intercept and detain small
amounts of sediment from disturbed areas of limited extent, preventing
sediment from leaving the site. See Figure 4.17 for details on straw bale
barriers.
Conditions of Use Below disturbed areas subject to sheet and rill erosion.
• Straw bales are among the most used and least effective BMPs. The
best use of a straw bale is hand spread on the site.
• Where the size of the drainage area is no greater than 1/4 acre per 100
feet of barrier length; the maximum slope length behind the barrier is
100 feet; and the maximum slope gradient behind the barrier is 2:1.
• Where effectiveness is required for less than three months.
• Under no circumstances should straw bale barriers be constructed
in streams, channels,or ditches.
• Straw bale barriers should not be used where rock or hard surfaces
prevent the full and uniform anchoring of the barrier.
Design and Bales shall be placed in a single row, lengthwise on the contour, with ends
Installation of adjacent bales tightly abutting one another.
Specifications All bales shall be either wire-bound or string-tied. Straw bales shall be
installed so that bindings are oriented around the sides rather than along
the tops and bottoms of the bales in order to prevent deterioration of the
bindings.
• The barrier shall be entrenched and backfilled. A trench shall be
excavated the width of a bale and the length of the proposed barrier to
a minimum depth of 4 inches. The trench must be deep enough to
remove all grass and other material that might allow underflow. After
the bales are staked and chinked (filled by wedging), the excavated
soil shall be backfilled against the barrier. Backfill soil shall conform
to the ground level on the downhill side and shall be built up to 4
inches against the uphill side of the barrier.
• Each bale shall be securely anchored by at least two stakes or re-bars
driven through the bale. The first stake in each bale shall be driven
toward the previously laid bale to force the bales together. Stakes or
re-bars shall be driven deep enough into the ground to securely anchor
the bales. Stakes should not extend above the bales but instead should
be driven in flush with the top of the bale for safety reasons.
• The gaps between the bales shall be chinked (filled by wedging) with
straw to prevent water from escaping between the bales. Loose straw
scattered over the area immediately uphill from a straw bale barrier
tends to increase barrier efficiency. Wedging must be clone carefully
in order not to separate the bales.
February 2005 Volume II—Construction Stormwater Pollution Prevention 4-89
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Section A - A
5' 6,
( .5 1.8m) jJ/r-1/ 77-..TT7.... ..
• Ponding Height
S\oij7
—+- —} Zt4\`�� _ Embed Straw Bale
• %��' \\,�\/\\/�// 4"(100mm)Minimum
// into Soil
it
Angle Stake Toward
Previous Bale to
Section B - B A Provide Tight Fit
I
t• I;
II
Wooden Stake
or Rebar Driven
Through Bale.
Plan �
B
r IIG XL
Mr �.
NOTES:
I.The straw bales shall be placed on slope contour.
2.Bales to be placed in a row with the ends tightly abutting.
3.Key in bales to prevent erosion or flow under bales.
Figure 4.17 Straw Bale Barrier
February 2005 Volume 11—Construction Stomiwater Pollution Prevention 4-91
s .
BMP C231: Brush Barrier
Purpose The purpose of brush barriers is to reduce 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.
Conditions of Use • Brush barriers may be used downslope of all disturbed areas of less
than one-quarter acre.
• Brush barriers are not intended to treat concentrated flows, nor are
they 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 barrier, rather than by a sediment pond, is when the
area draining to the barrier is small.
• Brush barriers should only be installed on contours.
Design and • Height 2 feet (minimum) to 5 feet (maximum).
Installation • Width 5 feet at base (minimum) to 15 feet(maximum).
Specifications
• Filter fabric (geotextile) may be anchored over the brush berm to
enhance the filtration ability of the barrier. Ten-ounce burlap is an
adequate alternative to filter fabric.
• Chipped site vegetation, composted mulch, or wood-based mulch (hog
fuel) can be used to construct brush barriers.
• A 100 percent biodegradable installation can be constructed using 10-
ounce burlap held in place by wooden stakes. Figure 4.18 depicts a
typical brush barrier.
Maintenance • There shall be no signs of erosion or concentrated runoff under or
Standards around the barrier. If concentrated flows are bypassing the barrier, it
must be expanded or augmented by toed-in filter fabric.
• The dimensions of the barrier must be maintained.
If required,drape filter fabric
over brush and secure in 4"x4"
min.trench with compacted `'�"� ,. ,�M ,;,+�`#�+„.4f#4.
backfill. Z►......
+"~•+�`•�•�� .. -Anchor downhill edge of
�. %. #++,+#++•� / „� filter fabric with stakes,
�"°" "~�+'�+:;4+i•�' sandbags,or equivalent.
riV
.IZ ,,,,,,L 2'Min_Height
Min. 5'wide brush barrier with I
max.6"diameter woody debris. .
Alternatively topsoil strippings
may be used to form the barrier. •
Figure 4.18-Brush Barrier
4-92 Volume II-Construction Stormwater Pollution Prevention February 2005
. •
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 fabric used
'i®ieiiiiiniiii i'I B —__{
•
—wiiraioEia:re2o
•ieiii iiiiin C4iiiCi I Filter fabric
=EEEBEPJ MN I E
'iv'eie;iiie N
!nouu HMI
ieimn i i iEinaminie, I I ini
-ii,u ,i e. 48W ni s i „, L Ii iii p i,I,ii u�—��, lL
E
6'max -"--I I Minimum 4"x4"trench ' 1 _
// Backfill trench with native soil/ N
Post spacing may be increased or 3/4"-1.5"washed gravel JI
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):
4-94 Volume 11-Construction Stormwater Pollution Prevention February 2005
•
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.
4-96 Volume II—Construction Stormwater Pollution Prevention February 2005
•
• Any damage shall be repaired immediately.4111
Maintenance • 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.
• 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.
Pending height POST SPACING:
max.24" 7'max.en open nsas
s Top of Fabric
4'max,on melding areas
:.�' ,n Belt
Attach fabric I. 1 L.
upstream side of post ; 1 I
tOp b it
FLOW--.- I'♦
drive ova,•ach Nero of { POST DEPTH:
slit fence 2 to 4 awes y As much Ml•w ground
with deHce Meeting C as fabric above'retied
60 p.s.l.or greater
co too^/, rnpaetlo` toot/eantpaca.n Otagonat ettacfvrwrt
` doubles strength
/ :r /j//\/A,
/ /\/\,'\� \\�/ /•�\\ ATTACHMENT DEWS:
�j� .%1�'• .j///\\/. . •Gather fabric al posts,r needed.
/\./\j\ \\\/\\/ \ \ •Utilize three ties per post.all within top e'of fabric.
/ /\\% \' •Position each tie diagonally,pta'sroaing holes vertically✓/�/ /�/ /// a minimum of 1'apert-
•Hang each tie an a post nipple end tigtxen yecuety.
No more than 24"of a 36"fabric use cable ties(sans)or soft wio-
is allowed above ground.
Roll of silt fence
.4 Oppration
:44:4111&......... 1111
Post
__ • installed
afterb. _ compaction
�� Fabric
liabove Sift Fence
tr&tic
.rib/ 41, d
v •r/$'� �,,,� \\\\
��1cz t� `t ij 200 30(}rnmft,.:;.0" t ..f.,..,,....e;:,:,,,,,,...:,:,..., ..:,..,,,,..,,,
v i
:{,.; ',�,; :/C.f_: :,,1\lit\\\\\\1\\\\�!\\\ t
Horizontal chisel point Siting blade
(76 nim ektit4 (18 mm width)
Completed installation
Vibratory plow is not acceptable because of horizontal compaction
Figure 4.20—Silt Fence Installation by Slicing Method
4-98 Volume II—Construction Stormwater Pollution Prevention February 2005
! r
5.3.1 Dispersion and Soil Quality BMPs (Required for Manual
Equivalency)
The following BMPs pertain to dispersion and soil quality applications.
BMP T5.10 Downspout Dispersion
Purpose and Definition
Downspout dispersion BMPs are splashblocks or gravel-filled trenches
that serve to spread roof runoff over vegetated pervious areas. Dispersion
attenuates peak flows by slowing entry of the runoff into the conveyance
system, allows for some infiltration, and provides some water quality
benefits.
Applications and Limitations
• Downspout dispersion is required on all subdivision single family lots
which meet one of the following criteria:
1. Lots greater than or equal to 22,000 square feet where downspout
infiltration is not being provided according to the requirements in
Volume III, Chapter 3.
2. Lots smaller than 22,000 square feet where soils are not suitable
for downspout infiltration as determined in Volume III, Chapter 3
and where the design criteria below can be met.
• All other projects required to apply Roof Downspout BMPs must
provide downspout dispersion if downspout infiltration is not feasible
or applicable as determined in Volume III, Chapter 3, and if the design
criteria below can be met.
Flow Credit for Roof Downspout Dispersion
If roof runoff is dispersed according to the requirements of this section on
single-family lots greater than 22,000 square feet, and the vegetative
flowpath' is 50 feet or larger through undisturbed native landscape or
lawn/landscape area that meets BMP T5.13, the designer may click on the
"Credits" button in the WWHM and enter the percent of roof area that is
being dispersed.
General Design Guidelines
• Dispersion trenches designed as shown in the Figures 5.1 and 5.2 shall
be used for all downspout dispersion applications except where
* Vegetative flow path is measured from the downspout or dispersion system discharge point to the downstream
property line,stream,wetland,or other impervious surface.
February 2005 Volume V—Runoff Treatment BMPs 5-3
• •
house
I I .I I 1.........TI
roof
downspout
serves up
to o rod J J
50'min. L... 1 1
vegetated I L.............
gm,/path ""' L J
9
spas L _..
dock �. ..
downspout extension
NTS
splash
block
Figure 5.3—Typical Downspout Splashblock Dispersion
Additional Design Criteria for Dispersion Trenches
• A vegetated flowpath of at least 25 feet in length must be maintained
between the outlet of the trench and any property line, structure,
stream, wetland, or impervious surface. A vegetated flowpath of at
least 50 feet in length must be maintained between the outlet of the
trench and any steep slope. Sensitive area buffers may count towards
flowpath lengths.
• Trenches serving up to 700 square feet of roof area may be simple 10-
foot-long by 2-foot wide gravel filled trenches as shown on Figure 5-1.
For roof areas larger than 700 square feet, a dispersion trench with
notched grade board as shown in Figure 5-2 may be used as approved
by the Local Plan Approval Authority. The total length of this design
must provide at least 10 feet of trench per 700 square feet of roof area
and not exceed 50 feet.
• A setback of at least 5 feet must be maintained between any edge of
the trench and any structure or property line.
• No erosion or flooding of downstream properties may result.
February 2005 Volume V-Runoff Treatment BMPs 5-7
• •
Appendix D
Jefferson County Landslide Information
Map Output • Page 1 of 1
FEATURES NOT SURVEYED
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FOR INFORMATIONAL PURPOSES ONLY-
Jefferson County does not attest to the accuracy of the data contained herein and makes no warranty with
respect to its correctness or validity. Data contained in this map is limited by the method and accuracy of its
collection. Mon Jul 03 10:18:34 2006
http://gisserver/servlet/com.esri.esrimap.Esrimap?ServiceName=ovmap&ClientV ersion=4.0&Form=True... 7/3/2006
• •
Appendix E
Stormwater Site Plan Template
* •
,. SoN C4
ker%r,%, JEFFERSON COUNTY
7 DEPARTMENT OF COMMUNITY DEVELOPMENT
p,.t 621 Sheridan Street • Port Townsend • Washington 98368
4 O 360/379-4450 • 360/379-4451 Fax
N http://www.co.fefferson.wa.us/comrndevelopment/
STORMWATER SITE PLAN SUBMITTAL TEMPLATE
MLA# PROJECT/APPLICANT NAME: M T, -- aesicIence, roie(t
Please answer all of the following questions to the best of your ability. Where the question calls for depiction on a site map, the
applicant may choose to either incorporate the elements into the general plot plan for the Master Land Use Application or to submit a
separate stormwater site plan map.
Ali reIei-encLS ore', tc: -tbo WI t&i" f,)Ian: Bnrne f 1-1 ii h•;i i-i`- oreHior
Project Overview
1. Describe the proposed developed conditions of the site. Indicate position and relative size of proposed improvements on the
site map.
See_ Sc-c h t,i 1. I - Prop t- Darn r,?h r:-)
J
Existing Conditions Summary
2. Describe the existing topography. Indicate contours on the site map.
SeC_ .ScrfiE "'t 2 .( - EEx101'd1( .463(-1;17)il\./
3. Describe the existing vegetation. Indicate native vegetation areas on the site map.
;1 ;` 5 [tiiY 2. 1 - E\fiShfQ I;PCr&+,ll11()
,J
4. Describe the existing soils. Indicate soil type on the site map.
5. Describe the existing site hydrology(i.e.,drainage; behavior of water on the site—above, below, and on the ground). Indicate
existing stormwater drainage to and from the site on the site map. Depict separate drainage basins on the site map, if
applicable,and indicate acreage of each.
<S c e .CPC 11 on 2-.5 - 1PPr r11("111 e 1 t ,Sir I al Id )t_e►" (t 11 m I iV izi-, - E X 1 s:tl tl n Sift i-1,1drrAcrrii
J
6. Describe any excess levels of noise generated by the proposed use or activity:
On e.
stormwater site plan template—rev.10/1/2003 5
•
13. Describe the water quality system.
rfi(h) 2..5 - I i cv!Orin
14. Describe the conveyance system analysis and design.
nil 1Qf r)i2t ).C.
52n - �'c c 'cfl G - - i fe S;Twin(;),- -C r M a"ro-.er;rn+
J_
15. Describe the source of fill material,physical characteristics of fill material,and deposition of excess material.
1711 (;: . nE t;:;- i1-z,"hvf m)t-rrDi
16.• Proposed methods of placement and compaction consistent with the applicable standards on Appendix Chapter 33 of the
Uniform Building Code.
f
l f l _,t 2T1 r S 1121( 'in i-' c r"'rn if&r
17. Describe the proposed surfacing material.
i;7 C:r) . G S'S (ltz-. )ble l� iti'i"j cr(•r)SS°Jip Ir.rtc t-C, C'1a.;�i
a
18. Describe methods for restoration of the site.
Tied t-lori'd <-i2',,)`, 1,0ji Futter be hi.iii]" cr') i"'t'(l?[Yi(-- d u r
Cr C.:r D iee St)el it"rl sL-P A . C.
. .
19. An Operation and Maintenance Manual is required for each flow control and treatment facility. [This is normally required for
"large"projects only and only those for which facilities are required to control flow or treat runoff.] If included,list the Manuals
here.
Solt Seft on 2- 1 Ci ;To(ate(.-- wice f-''1.asilf,-)1 .
20. List here and include any special reports or studies conducted to prepare the Stormwater Site Plan.
Sec) 2 - tip(l-1i (dpprr1i- and,
21. List other necessary permits and approvals as required by other regulatory agencies. If those permits or approvals include
conditions that affect the drainage plan or contain more restrictive drainage-related requirements,describe those conditions or
restrictions here.
Sec Si'C-_h on 2=1 - (''Thee, Perm n r i s
stormwater site plan template-rev.10/1/2003 7
• •
12 Required Elements—Construction SWPPP(continued)
8. Stabilize Channels and Outlets.
See Se(fThf ? - Herne:of
9. Control Pollutants.
36,2 1t'C1ion E t rin �i
10. Control De-Watering(the act of pumping groundwater or stormwater away from an active construction site).
SccJi'un 3 -- El-rmle,--)f IC
11. Maintain Best Management Practices(BMPs).
('k r h Lie t'Yme(J i it
•
12. Manage the Project.
- Ci erne I-1t 12
2. Adjacent Areas.
a. Description of the adjacent areas that may be affected by site disturbance (e.g., streams, lakes, wetlands, residential
areas,roads).
t'i`its
,>I .-?nv �C(ic�Ct'',7� �4(' S G,til j,t�' .?�fc�C' C1 _ ivilT
CCb :rc !:: L(ChA !"el' hc. ii1J1c-?1ff Ci DC( i Gi�T .�tl�l t�z'.' l7r� .; ( Z,
C 231 or`"
b. Description of the downstream drainage path leading from the site to the receiving body of water(minimum distance of 400
yards).
\ic it, i\ii,nc t,),��Et S _�Ct 1Cr�1 I Ill', C?i-r o r11r` Cr cri fT�
3. Environmentally Sensitive Areas.
a. Description of environmentally sensitive areas that are on or adjacent to the site.
See 5cr-hcn 2_ i - ('rih(t-Di
stormwater site plan template-rev.10/1/2003 9
i •
SECTION II—EROSION AND SEDIMENT CONTROL PLAN
Sediment and erosion control measures may be depicted on the master land use application plot plan,a stormwater site plan,and/or a
separate Construction SWPPP site plan. This is a checklist to ensure that the following are depicted on a site plan:
1. General.
a. Vicinity Map
b. Jefferson County Approval Block
c. Erosion and Sediment Control Notes
2. Site Plan.
a. Legal description of subject property.
b. North arrow.
c. Indicate boundaries of existing vegetation(e.g.,tree lines,pasture areas,etc.).
d. Identify and label areas of potential erosion problems.
e. Identify FEMA base flood boundaries and Shoreline Management boundaries(if applicable).
f. Show existing and proposed contours.
g. Indicate drainage basins and direction of flow for individual drainage areas.
h. Label final grade contours and identify developed condition drainage basins.
i. Delineate areas that are to be cleared and graded.
j. Show all cut and fill slopes indicating top and bottom of slope catch lines.
3. Conveyance Systems.
a. Designate locations for swales,interceptor trenches,or ditches.
b. Show all temporary and permanent drainage pipes,ditches, or cut-off trenches required for erosion&sediment control.
c. Provide minimum slope and cover for all temporary pipes or call out pipe inverts.
d. Shows grades,dimensions, and direction of flow in all ditches,swales,culverts and pipes.
e. Provide details for bypassing off-site runoff around disturbed areas.
f. Indicate locations and outlets of any dewatering systems.
- • 4. Location of Detention Best Management Practices(BMPs). Identify location of detention BMPs.
5. Erosion and Sediment Control Facilities.
a. Show the locations of sediment trap(s),pond(s), pipes and structures.
b. Dimension pond berm widths and inside and outside pond slopes.
c. Indicate the trap/pond storage required and the depth,length,and width dimensions.
d. Provide typical section views through pond and outlet structure.
e. Provide typical'details of gravel cone and standpipe,and/or other filtering devices.
f. Detail stabilization techniques for outlet/inlet.
g. Detail controVrestrictor device location and details.
h. Specify mulch and/or recommended cover of berms and slopes.
i. Provide rock specifications and detail for rock check dam(s), if applicable.
j. Specify spacing for rock check dams as required.
k. Provide front and side sections of typical rock check dams.
I. Indicate the locations and provide details and specifications for silt fabric.
m. Locate the construction entrance and provide a detail.
6. Detailed Drawings. Any structural practices used that are not referenced in the Ecology Manual should be explained and
illustrated with detailed drawings.
7. Other Pollutant BMPs. Indicate on the site plan the locations of BMPs to be used for the control of pollutants other than
sediment(e.g.,concrete wash water).
8. Monitoring Locations. Indicate on the site plan the water quality sampling locations to be used for monitoring water quality on
the construction site. Sampling stations should be located upstream and downstream of the project site.
stormwater site plan template—rev.10/1/2003 11
Appendix F •
Permeable Surfacing and Catch Basin Detail
Invisible Structures - Grass ve2 Page 1 of 2
•
StR uctu e,s,znc.
State of the Earth formation'
�rar€ctt 2 brain 2 Grass 2 Gravel- 2 Rain 2 Slope 2
Tech Specs Grasspave2 Brochure Design Details Project Profiles Large Rolls Installation(Flash)
Data Sheet Competitive Advantages Material Safety Hydrogrow Roll Sizes Sand Root Zone
Product Data Sheet- Grasspave2
Grasspave2 is an exciting,"invisible"porous paving technology that combines recycled raw materials,sound structural
engineering,efficient production and installation techniques,and proven horticultural methods to give designers a living turfgrass
alternative to asphalt and concrete for traffic-bearing surface applications.
Grasspave2 protects and enhances the environment in three ways:First,made from 100%recycled plastic,Grasspave2 keeps
common consumer and industrial products from going into landfills.Second,grass paving directly improves the environment by
recharging water tables on site(reducing flooding hazards downstream),reducing sources of oils and solvents from asphalt,
absorbing carbon dioxide,and creating oxygen.Third,it enhances the beauty and quality of the built environment--replacing hot
asphalt-paved areas with cool,sparkling green lawn-like spaces.
Product Description
Grasspave2 has thin-walled independent plastic rings connected by an interlocking geogrid structure,which,because it is installed
below the surface,is invisible in the completed project.While the rings are rigid,the grid itself is flexible,which makes it easy to
install on uneven grades,and reduces usual cut and fill requirements.
The rings transfer loads from the surface to the grid structure and engineered base course material below,thus preventing
compaction of the upper root zone of the grass.Small loads,such as shoes,are supported by a single ring;tires and large loads are
supported by several rings.
The rings also act to contain the root zone medium(usually sand)and prevent lateral migration away from tires,feet,or other
loads.This protects and stabilizes the grass root system,enabling roots to grow deep into the porous base course.The result is
healthy,green turf at the surface.
Mats can be rolled out in minutes! 600 m2(6,000 st)per two-person hour,plus time for base course preparation and grass
installation(seeding,sod,or sprigging). Step-by-step instructions are included in our Installation Instructions,which accompany
each order.
Features and Benefits
• Allows 100%grass coverage
• Made from 100%post-consumer recycled plastic
• High strength to weight load-bearing capacity
• Supports vehicular and pedestrian traffic
o parking lots
O firelanes
O overflow and event parking
o golf cart paths
O residential driveways
o maintenance and utility access
• Maximum porosity
o zero to low runoff
o free air/water movement
• Permits more trees in parking areas
http://www.invisiblestructures.com/GP2/grasspave_data.htm 7/11/2006
0 •
U,, n i Eco -Stone 0 .
, The Uni Eco-Stone paving system is an innovative,environmentally-beneficial
-
pavement system designed to reduce stormwater runoff.When installed,the
Tommmilaw...Ns'` a �" unique patented design creates drainage openings in the pavement surface
"�_ `. ` which facilitate rainwater infiltration. Uni Eco-Stone is a true interlocking
` �„•, ' concrete paver that can support heavy vehicular loads, unlike some other
�w__..,.,. :,r;_ > types of permeable pavement systems. Uni Eco-Stone can be installed in
it �:ipx several patterns and used in a variety of applications.
"'"� __.___-----""yam~~ Uni Eco-Stone pavers are perfect for residential,municipal,commercial and
."- industrial applications,including:
r' ., „� •Driveways •Industrial plants
•Parking lots •Industrial yards
•Gas stations •Factory streets
•Bridge abutments •Highway ramps
•Crosswalks •Bridge underpasses
•Street medians •Bus terminals
•Intersections • Industrial/Commercial ports
lip8 cmx 22.9 cmx ll.4cm
„, 4."`� 3'ls"x9"x4'V
Product Data*
Coverage Pieces per Pallet Coverage per Pallet Weight per Piece Weight per Pallet
3.52 pcs/ft2 (37.9 pcs/m2) 320 90.8 ft2(8.44 m2) 10 lb. (4.5 kg.) 3,250 lbs.
All Weight per Pallet noted above include a 50 lb pallet weight.
All metric dimensions are soft converted to Imperial.Dimensions and coverage include 1.5 mm('/.re"J joint.
9
.-2y
# IN. N
' 2/4
I 47h
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Height/Thickness Width Length Stones/sq ft of Void
3.125 inch(80 mm) 4.5 inch (115 mm) 9 inch (230 mm) 3.55 12.18%
All Weight per Pallet noted above include a 50 lb pallet weight.
All metric dimensions are soft converted to Imperial.Dimensions and coverage include 1.5 mm('/:.")joint.
Standard Specification
Uni Eco-Stone pavers are manufactured to Mutual Materials standard specifications as well as ASTM:C 936.
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