HomeMy WebLinkAbout05- StormwaterSON oo
DEPARTMENT OF COMMUNITY DEVELOPMENT
621 Sheridan Street, Port Toxvnsend, WA 98368
Tel: 360.379.4450 1 Fax: 360.379.4451
Web:\i,wu•.co.jefferson.wa.us/comnwnitvdevetopnient
] :-mail: dcd(&co.iefferson.wa.us
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STORMWATER CALCULATION WORKSHEET
PARCEL# 001334021 PROJECT/APPLICANT NAME: CHARLES SOUTHARD - SFR
Scan the QR
code to access
the digital form
DETERMINING STORMWATER MANAGEMENT REQUIREMENTS: This stormwater calculation worksheet should be completed first to
classify the proposal as "small," "medium," or "large." The size determines whether a Stormwater Site Plan is required in
conjunction with a stand-alone stormwater management permit application, building permit application, or other land use approval
application that involves stormwater review. The basic information will also be helpful for completing a Stormwater Site Plan, if
reauired.
PARCEL SIZE (I.E., SITE)
Size of parcel 10.31 acres An acre contains 43,560 square feet. Multiply the acreage by this figure.
Size of parcel in square feet 449,104 sq/ft
Land -disturbing activity is any activity that results in movement of earth, or a change in the existing soil cover (both vegetative and
non -vegetative) and/or the existing soil topography. Land disturbing activities include, but are not limited to clearing, grading, filling,
excavation, and compaction associated with stabilization of structures and road construction.
Native vegetation is vegetation comprised of plant species, other than noxious weeds, which reasonably could have been expected
to naturally occur on the site. Examples include species such as Douglas fir, western hemlock, western red cedar, alder, big -leaf
maple, and vine maple; shrubs such as willow, elderberry, salmonberry, and salal; herbaceous plants such as sword fern, foam
flower, and fireweed.
LAND DISTURBING ACTIVITY, CONVERSION OF NATIVE VEGETATION, AND VOLUME OF CUT/FILL
Calculate the total area to be cleared, graded, filled,
excavated, and/or compacted for proposed development
project. Include in this calculation the area to be cleared for:
Construction site for structures 3,441 sq/ft
Drainfield, septic tank, etc. 1,440 sq/ft
Well, utilities, etc.
1,000
sq/ft
Driveway, parking, roads, etc. 3,830 sq/ft
Lawn, landscaping, etc. 6,099 sq/ft
Other compacted surface, etc.
Temporary construction area
Total Land Disturbance
15,810
sq/ft
sq/ft
Answer the following two questions related to
conversion of native vegetation:
Does the project convert % acres or more of
native vegetation to lawn or landscaped areas?
Circle: Yes No
Does the project convert 2'/2 acres or more of
native vegetation to pasture?
Circle: Yes No
Indicate Total Volumes of Proposed:
(Includes BMP T5. 13 Fill Volume)
sq/ft Cut 260 Fill 260 (cu/yd)
stormwater talc worksheet OR code — REV. 5/31/2019 page 1 of 2
STORMWATER CALCULATIONS — IMPERVIOUS SURFACE
Impervious surface is a hard surface that either prevents or slows the entry of water into the soil 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 roof 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.
NEW
Structures (all roof area) 3,066 sq/ft
Sidewalks sq/ft
Patios
375 sq/ft
Solid Decks sq/ft
(without infiltration below)
Driveway, parking, roads, etc 3,830 sq/ft
Other
Total New 7,271 sq/ft
EXISTING
Structures (all roof area) 735 sq/ft
Sidewalks sq/ft
Patios
Solid Decks
(without infiltration below)
sq/ft
sq/ft
Driveway, parking, roads, etc 7,455 sq/ft
Other sq/ft
Total Existing 8,190 sq/ft
TOTAL NEW + TOTAL EXISTING* 15,461 sq/ft *This amount will be used to check total lot coverage.
DEVELOPMENT v. REDEVELOPMENT
Divide the total existing ♦ Does the site have > 35% or more no
impervious surface above by the existing impervious surface?
size of the parcel and convert to
a percentage. 3.44
The proposal is considered new development. Answe
yes questions in Figure 2.4.1 Flow Chart for New
*00 (�eveIopment to determine project size (next page).
The proposal is considered redevelopment Answer
questions in Figure 2.4.2. Flow Chart for
Redevelopment to determine project size (next page).
— Applicants for "small" projects must comply only with Minimum Requirement #2—Construction Stormwater Pollution Prevention.
Please submit the Small Project Certification (Worksheet "s). The proponent is responsible for employing the 12 Elements to control
erosion and prevent sediment and other pollutants from leaving the site during the construction phase of the project. Pick up the
Construction Stormwater Pollution Prevention (SWPPP) Best Management Practices (BMPs) Fact Sheet.
— Applicants for "medium" projects —those that must meet only Minimum Requirements #1 through #5 must submit Worksheet Al
and B1, a stormwater site plan and a construction stormwater pollution prevention site plan (See Reference A1A and 61A for
guidance).).
— "Large" projects —those that must meet all 9 Minimum Requirements— must submit Worksheet Al and 61, a stormwater site plan
and a construction stormwater pollution prevention site plan (See Reference A1A and 131A for guidance). Large projects also may
require engineering. See Worksheet L to determine additional large project requirements.
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.
U)ez;agi2 , PE (Weinberg Engineering) 6/24/22
(LANDOWNER OR AUTHORIZED REPRESENT (iVESIGNATURE) (DATE)
stormwater calc worksheet QR code — REV. 5/31/2019 page 2 of 2
Figure 2.4.1 Flow Chart for New Development
Start Here
Does the site have 1
35% or more of
existing impervious
coverage?
No)
Does the project
result in 5,000
square feet, or
greater, of new plus
replaced hard
surface area?
es
All Minimum
Requirements apply
to the new and
replaced hard surfaces
and converted
vegetation areas.
This is a "large" project.
Large projects refer to
Worksheet L for submittal
requirements. At a
minimum all large Project
Yes
Does the project convert
3/4 acres or more of
vegetation to lawn or
landscaped areas, or
No convert 2.5 acres or more
of native vegetation to
pasture?
Yes
Minimum Requirements
#1 through #5 apply to
the new and replaced
hard surfaces and the
land disturbed.
See Redevelopment
Minimum
Requirements and
Flow Chart
(Figure 3.3)
Does the project
No result in 2,000 square
feet, or greater, of
new plus replaced
hard surface area?
Yes ' No
/ Does the project have
land disturbing
activities of 7,000
Yes square feet or greater?
No
must submit Worksheet Minimum '
Al, Bl, and C or Requirement #2
equivalent. applies.
Complete "SmallProject C:ertii-ication VVor
Project must follow Construction Pollution
Figure 2.4.1 — Flow Chart for Determining Requirements for New Development
Volume 1—Minimum Technical Requirements —August 2012
2-10
Fact Sheet
>_ Worksheet L
J
%s 0 Large Projects
Large Projects subject to Minimum Requirements #1 Does the project discharge to a sub basin draining to salt water,
-9 must complete Worksheet Al as applicable. Also y
Dosewallips River, or Hoh River?
complete Worksheet B1.
no
Does the project meet feasibility criteria
for full dispersion (see Worksheet Cl)?I- no
Yes
No Further action needed.
Demonstrate full dispersion
on site plan.
1
Is the project in the Urban
Growth Area?
F
o
1
Yes
Use List #3 on Worksheet Al page 6.
No further action is needed.
Fthe project on a parcel 5 acres or larger?
Yes F
o
The proponent must submit
a stormwater report and site
plan prepared by a licensed
engineer that complies with
the 2012 Department of
Ecology Stormwater Man-
agement Manual for West-
ern Washington as amended
in 2014.
The report prepared by the
engineer must demonstrate
compliance with the LID
Performance Standard and
all minimum requirements.
For each surface consider
the BMPs in the order listed
in List #1 page 5 in
Worksheet Al, except,
raingardens may not be
used. This process is equiva-
lent to List #2 in the 2012
Department of Ecology
Stormwater Management
Manual for Western
Washington as amended in
2014.
Yes
Worksheet Al
,! t.------ . Medium & Large Project Report
Minimum Requirement # 1 : Preparation of Stormwater Site Plan
Complete the following:
Submit a site plan demonstrating the project. Refer to REFERENCE A1A for examples of Best Management
Practices (BMP's) that you can use. Remember that all site plans submitted for the project must be consistent
and accurate.
X❑ Describe both existing and proposed site conditions for the following items as applicable in the space below each
bullet point. Attach additional pages if needed.
• structures
• Existing driveway, shed and barn. Proposed driveway addition, house, carport, and shop.
• Night Owl Rd runs across the NW property corner and adjacent to the west property line, west of the site
11fility Inrntinnc
• I Proposed water service line and power on northwestern portion of site.
• Proposed drainfield and septic tank.
• storm waer run-on from neighOoring properties
None observed. Surrounding properties and project site are very flat.
• expected excavation depths an vo umes
• 1-2 feet
None
Minimum Requirement # 2 : Construction Stormwater Pollution Prevention Plan (SWPPP
A SWPPP is designed to be a stand-alone document that addresses construction stormwater management concerns. This
document is required to be kept by the contractor performing the work at the jobsite for reference and update during
the life of the project. Construction BMP's must be indicated on the stormwater site plan. REFERENCE B1A includes
diagrams of common BMP's that may be used on the site plan.
XO My completed SWPPP (WORKSHEET B1 or equivalent) is included in this application packet!
Minimum Requirement # 3 : Source Control of Pollution (not construction related)
The intent of source control is to prevent stormwater from coming in contact with pollutants. Source control BMPs
can be operational or structural in nature. A roof over a material storage area is an example of a structural source
control BMP. Washing your vehicle on the lawn rather than in the street is an operational BMP. This requirement
is generally not applicable to Single Family Residences (SFRs); however, ways to minimize pollution from moving
downstream should be considered during the design phase of every project. Specifications on standard source control
BMPs that are applicable to various commercial and industrial -type facilities can be found in Volume IV of the 2014
Stormwater Management Manual for Western Washington (SWMMWW) (continued on page 2).
page 1 of 6
Worksheet Al
-- _ Medium & Large Project Report
Minimum Requirement # 3 : Source Control of Pollution (continued from page 1)
Check one of the following boxes that best represents your project with regards to MR #3.
My project is a Single Family Residence (SFR) and after considering operational and structural measures to prevent
stormwater from coming in contact with pollutants, I have:
® determined this MR to not be applicable. ❑ made appropriate adjustments to my project.
❑ My project is not a SFR and after reviewing Vol. IV of the SWMMWW, I have determined that this MR is not
applicable because of the following reason:
❑My project is not a SFR and after reviewing Vol. IV of the SWMMWW, I have determined that the following source
control BMPs are applicable to my project and shall be incorporated into the project design and operation.
page 2 of 6
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(J� Worksheet Al
,!4---~ Medium & Large Project Report
Minimum Requirement # 4 : Preservation of Natural Drainage Systems
Creating new drainage patterns results in more site disturbance and more potential for erosion and sedimentation during
and after construction. to the maximum extent possible, proponents must 1) maintain the natural on -site drainage
pattern and concentrated discharge location at the downstream property boundary, and 2) prevent erosion at and
downstream of the discharge location.
NOTE: All outfalls require energy dissipation. See Table 4.5.1 in Vol. V of the SWMMWW for minimum design standards
for rock protection at outfalls.
Choose the option below that best describes your project:
The project site does not currently have any intermittent, seasonal, or continuous concentrated water
moving across any part of the property and the proposed improvements to the site will not create new
concentrated flow paths or not discharging to existing drainage systems.
X❑ The project site has existing concentrated flow drainage systems and outfalls. (NOTE: These items must
be graphically shown on the Site Plan or equivalent, to include: type, slope, dimensions, channel lining,
direction of flow, buffer, etc.) Select below how it will be addressed.
® This project will not alter the existing drainage system in any way. If the existing outfall(s) show
signs of erosion and scour, energy dissipation measures will be installed or improved upon.
Construction activity of any kind will not occur within at least 10 ft. of the edge of the channelized
flow. BMP C102: BUFFER ZONES will be implemented during the life of the project to include visible
flagging or other demarcation technique.
The existing concentrated drainage system traversing the property will be impacted as part
of this project, as described in the space below and shown on the site plans. Engineering
calculations are required that show the altered drainage design can accommodate the existing
flows and the added runoff contributed by the project.
page 3 of 6
i` Cl \
a Worksheet Al
r
-- Medium & Large Project Report
Minimum Requirement # 5 : On -site Stormwater Management
On -site stormwater management techniques shall be implemented where possible to accommodate the permanently
added stormwater runoff being generated by development. Some on -site stormwater management techniques provide
better stormwater detention and treatment than others; however, they are not always appropriate for use due to varying
individual site characteristics. Therefore, techniques are presented to applicants on the next pages in a hierarchical order
and shall be considered for use in the order listed. The first technique on the list that is determined to be possible shall
be implemented. See WORKSHEET C to determine which techniques are feasible.
Runoff from developments occurring in drainage basins that drain directly or indirectly to a creek require a higher level
of stormwater management, thus, the techniques are presented in three lists below:
All properties will be in one of these three categories:
❑My project is located in a drainage subbasin that 0 My Project will discharge to a subasin draining to
drains to directly or indirectly to freshwater. salt water, Dosewallips River, or Hoh River.
PROCEED to Page 5 to use LIST #1. PROCEED to Page 6 to use LIST #3.
❑My project is a large project. Refer to Worksheet L. If full dispersion isn't feasible, use LIST #1
(List #2 and List #1 are the same except raingardens are not permitted in List #2).
page 4 of 6
,:,ON
Worksheet Al
_ Medium & Large Project Report
Minimum Requirement # 5 : On -site Stormwater Management (continued)
LIST # 1 : Applicable to projects that directly or indirectly drain to freshwater.
For each category below, proceed through the LIST from top down. Use WORKSHEET C to determine if the BMP
can be used. If number 1 on the list is not possible, document why on WORKSHEET C and move down to number
2, and so on.
INSTRUCTIONS: Check the first option that will work for Each Category Below:
Category A: Lawn and Landscape Areas
My project does not have disturbed soils not covered by impervious
surfaces.
1. Post -Construction Soil Quality and Depth
Disturbed soils shall be amended (BMP T5.13: ).
Category B: Roofs
My project does not have Roof areas.
1. Full Dispersion (BMP T5.30)
OR
Downspout Full Infiltration (BMP T5.10A)
2. Rain Garden (LARGE PROJECTS CANNOT USE)
(BMP T5.14A)
3. Downspout Dispersion System (BMP T5.1013)
1-1 4. Perforated Stub -Out Connection (BMP T5.10)
5. Each BMP above is infeasible, see WORKSHEET C. STOP.
COMPLETE AND SUBMIT WORKSHEET B1. NO OTHER
INFORMATION REQUIRED AT THIS TIME.
Category C: Other Hard Surfaces, e.g. gravel and paved
driveways, solid decks and patios without infiltration below
❑ My project does not have Other Hard Surface areas
1. Full dispersion (BMP T5.30)
2. Permeable Pavement (BMP T5.15)
OR
Rain Garden (LARGE PROJECTS CANNOT USE) (BMP T5.14A)
3. Sheet Flow Dispersion (BMP T5.12)
OR
Concentrated Flow Dispersion (BMP T5.11)
4. Each item above is infeasible, see WORKSHEET C. STOP.
COMPLETE AND SUBMIT WORKSHEET B1. NO OTHER
INFORMATION REQUIRED AT THIS TIME.
•J
Worksheet Al
--a- _ Medium & Large Project Report
Minimum Requirement # S : On -site Stormwater Management (continued)
LIST # 3 :Applicable to project that discharges to a subbasin draining to saltwater, the DosewaIIips River, or the Hoh
River.
INSTRUCTIONS: For each category, choose one option. Use Worksheet C to determine if the BMP can be used on the
site.
Category A: Lawn and Landscape Areas
My project does not have disturbed soils not covered by impervious surfaces.
1. Post -Construction Soil Quality and Depth
Disturbed soils shall be amended (BMP T5.13: ).
Category B: Roofs
My project does not have Roof areas.
1. Downspout Full Infiltration (BMP T5.10A)
*Optional - may elect to install BMP T5.14A Rain Garden*
2. BMP T5.10B: Downspout Dispersion System
❑ 3. BMP T5.10C: Perforated Stub -Out Connection
4. Each BMP above is infeasible, see WORKSHEET C.
Category C: Other Hard Surfaces
My project does not have Other Hard Surface areas
*Optional - may elect to install BMP T5.15: Permeable Pavement OR BMP T5.14A:
Rain Garden*
X❑ 1. BMP T5.12: Sheet Flow Dispersion
2. BMP T5.11: Concentrated Flow Dispersion
3. Each item above is infeasible, see WORKSHEET C. STOP. COMPLETE AND SUBMIT
WORKSHEET B1. NO OTHER INFORMATION REQUIRED AT THIS TIME.
page 6 of 6
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Worksheet B1
Construction Protection: Medium and Large Projects
(SWPPP: Stormwater Pollution Prevention Plan)
Submit a site plan demonstrating the construction protective measures or best management practices that will
be used for the project during the construction phase.
Refer to REFERENCE 131A for examples of Construction Best Management Practices (BMP's) that you can use. The
activities that take place during construction are the highest risk for stormwater problems such as erosion and
sediment control (you may need to provide an additional site plan with greater detail for stormwater features. If so,
make sure it is consistent with the primary site plan. Remember that all site plans submitted for the project must
be consistent and accurate).
Element 1: Preserve Vegetation / Mark Clearing Limits
The goal of this element is to preserve native vegetation and to clearly show the limits of disturbance.
Choose any of the following that apply:
XD The perimeter of the area to be cleared shall be marked prior to clearing operation with visible flagging, orange
plastic barrier fencing and/or orange silt fencing as shown on the SWPPP site plan. Vehicles will only be allowed
in the areas to be graded, so no compaction of the undeveloped areas will occur. If this option is selected check
the BMPS you will use below:
C 10 1 Preserving Natural C102 Buffer C103 High Visibility
Zones Fence
Vegetation
It is necessary to disturb the entire property during this project due to existing site conditions, property
constraints, and proposed design. I understand that all disturbed land not covered by hard surface at the end of
the project is subject to soil amendment requirements per BMP T5.13 Post -Construction Soil Quality and Depth.
The site was cleared as part of clearing activity that is subject to an enforcement action and will be re -vegetated.
Restoration may be necessary to comply with Critical Area Regulations or stormwater requirements. Buffer Zones-
BMP C102 may apply if Critical Areas exist on -site and buffer zones shall be protected.
Element 2: Construction Access
The goal of this element is to provide a stabilized construction entrance/exit to prevent or reduce or sediment
track out.
Choose one of the following:
X❑ The driveway to the construction area already exists and will be used for construction access. All equipment and
vehicles will be restricted to staying on that existing impervious surface. If sediment is tracked off site, the road-
way will be cleaned thoroughly at the end of each day.
A stabilized construction entrance will be installed prior to any vehicles entering the site, at the location
shown on the SWPPP site plan. If sediment is tracked off site, the roadway will be cleaned thoroughly at the end
of each day. If this option is selected check the BMPS you will use below:
C105 Stabilized C106 Wheel EJ C107 Construction
Construction Entrance / Wash Road / Parking Area
Exit Stabilization
page 1 of 6
u ! Worksheet B1
---- . Construction Protection: Medium and Large Projects
-�,S��Itl N Cs (SWPPP: Stormwater Pollution Prevention Plan)
��
Element 3: Control Flow Rates
The goal of this element is to construct retention or detention facilities when necessary to protect properties
and waterways downstream of development sites from erosion and turbid discharges.
This element does not apply to my project because (check any that apply):
0 Site is mildly sloped (<5%),
There are no individually sloped sections greater than 10%,
The bulk of the project is scheduled to occur during dry season (May 1-Sept 30)
Element 4: Sediment Control
The goal of this element is to construct sediment control BMPs that minimize sediment discharges from the
site.
Select one of the two statements applicable to the project.
X❑ The site has already been stabilized and re -vegetated.
Sediment control BMPs shall be placed at the locations shown on the SWPPP Site Plan. If this option is selected
check the BMPS you will use below:
❑ C231 Brush Barrier ❑ C233 Silt Fence ❑ C235 Wattles
C232 Gravel Filter C234 Vegetated
Berm Strip
Element 5: Stabilize Soils
The goal of this element is to stabilize exposed and unworked soils by implementing erosion control BMPs.
Select one of the three statements applicable to the project.
® My project will ensure the following:
• Soil stockpiles will be located within the disturbed area shown on the SWPPP Site Plan.
• Soil excavated for the foundation will be backfilled against the foundation and graded to drain away from the
building.
• No soils shall remain exposed and unworked for more than 7 days from May 1 to September 30 or more than
2 days from October 1 to April 30.
• Once the disturbed landscape areas are graded, the grass areas will be amended.
• All stockpiles will be covered with plastic or burlap if left unworked.
This element does not apply to my project because:
My project must implement specific BMP's to ensure compliance. (Check BMP's you will use on the next page).
page 2 of 6
Worksheet B1
,rw - Construction Protection: Medium and Large Projects
(SWPPP: Stormwater Pollution Prevention Plan)
C120 Temlorary & C122 Nets & Blankets C124 Sodding 0 C131 Gradient
Permanent Seeding Terraces
C121 Mulching C123 Plastic Covering C125 Topsoil 0 C140 Dust Control
Composting
C235 Wattles
Element 6: Protect Slopes
The goal of this element is to design and construct cut -and -fill slopes in a manner to minimize erosion.
Select one of the two statements applicable to the project.
Q No cut slopes over 4 feet high or slopes steeper than 2 feet horizontal to 1 foot vertical, and no fill slopes over
4 feet high will exceed 3 feet horizontal to 1 foot vertical. Therefore, there is no requirement for additional
engineered slope protection.
❑The above checkbox is not checked. My submittal is designed by a licensed geologist to protect slopes. Based on
the licensed professionals recommendation (please attach their evaluation), the following BMP's will be used:
C120 Temporary & Permanent F C205 Subsurface C207 Check Dams
Seeding Drains
C204 Pipe Slope Drains C206 Level Spreader C208 Triangular Silt Dike
(Geotextile-Encased Check Dam)
Element 7: Protect Permanent Drain Inlets
The goal of this element is to protect storm drain inlets during construction to prevent stormwater runoff from
entering the conveyance system without being filtered or treated.
Select one of the three statements applicable to the project.
❑ The site has open ditches in the right-of-way or private road right-of-way.
❑ X There are no catch basins on or near the site.
Catch basins on the site or immediately off site in the right-of-way are shown on the SWPPP Site Plan. Storm drain
inlet protection shall be installed. If this option is selected check the BMPS you will use below:
C220 Storm Drain Inlet Protection
page 3 of 6
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Worksheet B1
J
Construction Protection: Medium and Large Projects
I'S/f IN G �L (SWPPP: Stormwater Pollution Prevention Plan)
Element 8: Stabilize Channels and Outlets
The goal of this element is to design, construct, and stabilize on -site conveyance channels to prevent erosion
from entering existing stormwater outfalls and conveyance systems.
Select one of the three statements applicable to the project.
X❑ Construction will occur during the dry weather. No storm drainage channels or ditches shall be constructed either
temporary or permanent.
There are no existing or proposed stormwater conveyance channels on the project site.
A wattle shall be placed at the end of the Swale to prevent erosion at the outlet of the Swale. If this option is
selected check the BMPS you will use below:
C202 Channel Lining C207 Check Dams C209 Outlet Protection ❑ C235 Wattles
Element 9: Control Pollutants
The goal of this element is to design, install, implement and maintain BMPS to minimize the discharge of
pollutants from material storage areas, fuel handling, equipment cleaning, management of waste materials, etc.
This element does not apply to my project because (circle any that apply - If any box is unchecked this element applies.
There will be no concrete work,
❑ There will be no sawcutting work,
0 There will be no hazardous materials on -site,
aThere will be no fertilizer or pesticide application,
There will be no heavy equipment associated with this project,
1771
IA I There will be no pressure washing, equipment maintenance or dewatering
If one or more of the checkboxes above are unchecked. Any and all pollutants, chemicals, liquid products and other
materials that have the potential to pose a threat to human health or the environment will be covered, contained, and
protected from vandalism. All such products shall be kept under cover in a secure location on -site. Concrete handling
shall follow BMP C151 C154. If this option is selected check the BMPS you will use below:
C151 Concrete Handling (OFF -SITE DISPOSAL) M C152 Sawcutting and Surfacing
Pollution Prevention
C153 Material Delivery, Storage, and Containment C154 Concrete Washout Area
page 4 of 6
�Z�,O N
Worksheet B1
J
Construction Protection: Medium and Large Projects
1ffNCI'�
o ` (SWPPP: Stormwater Pollution Prevention Plan)
Element 10: Control De -watering
The goal of this element is to handle turbid or contaminated water from dewatering (removal of water)
separately from stormwater.
Select one of the two statements applicable to the project.
® No dewatering of the site is anticipated.
Dewatering of the site is anticipated. If this option is selected check the BMPS you
will use below:
C203 Water Bars C236 Vegetated Filtration ❑ C206 Level Spreader
Element 11: Maintain Best Management Practices
The goal of this element is to maintain and repair all temporary and permanent erosion and sediment control
BMPs to assure continued performance.
Describe the steps you will take:
❑Best Management Practices or BMPs shall be inspected and maintained during construction and removed within
X 30 days after the County Inspector or determines that the site is stabilized, provided that they maybe removed
when they are no longer needed.
Element 12: Manage the Project
The goal of this element is to ensure that the owner and those performing the site work comply with the
SWPPP and properly coordinate to ensure that all BMPs are deployed at the proper time to achieve full
compliance with county regulations throughout the project.
The SWPPP will be implemented at all times. If applicable to the project, erosion control BMPs will be
implemented in the following sequence:
1. Mark clearing limits
2. Install stabilized construction entrance
3. Install protection for existing drainage systems and permanent drain inlets
4. Establish staging areas for storage and handling polluted material and BMPs
5. Install sediment control BMPs
6. Grade and install stabilization measures for disturbed areas
7. Maintain BMPs until site stabilization, at which time they may be removed
page 5 of 6
(! Worksheet 131
_ Construction Protection: Medium and Large Projects
�o . (SWPPP: Stormwater Pollution Prevention Plan)
Element 13: Protect Low Impact Development BMPs
The goal of this element is to protect permanent stormwater management BMPs from siltation and compaction
during construction. The permanent stormwater management BMPs used for runoff from roofs and other hard
surfaces include: full dispersion, roof downspout full infiltration or dispersion systems, perforated stubout
connections, rain gardens, bioretention systems, permeable pavement, sheetflow dispersion, and concentrated
flow dispersion.
Methods that will be used to protect permanent stormwater management BMPs include:
Sequencing the construction in a fashion to install these permanent BMPs at the latter part of the
construction grading operations,
XI Excluding equipment from the BMPs and the associated areas,
❑Using the erosion and sedimentation control BMPs listed below to protect facilities such as drywells,
raingardens, permeable pavement, or bioretention from accumulating sediment during construction and
before site restoration. If this option is selected check the BMPS you will use below:
C102 Buffer Zone
C233 Silt Fence
❑ C231 Brush Barrier
❑ C103 High Visibility Fence
❑ C2 34 Vegetated Strip
Other
Applicant or Representative Signature �?�u.,Gc%6 ,PE
WEINBERG ENGINEERING
page 6 of 6
Worksheet C
What's the best option for your site?
Minimum Requirement #5 (On -Site Stormwater Management)
The following tables summarize the criteria that can be used to justify why you cannot use various stormwater
management best management practices (BMPs) for consideration for Minimum Requirement #5. This information is also
included under the detailed descriptions of each BMP in the Department of Ecology's Stormwater Management Manual for
Western Washington (SWMMWW [2014]). Where any inconsistencies or lack of clarity exists, the requirements in the main
text of the SWMMWW shall be applied.
HOW TO USE:
Evaluate the feasibility of the BMPs in priority order based on Worksheet Al page 5 (List #1) or 6 (List #3) or
Worksheet L for Large Projects (List #2). Only one criterion needs to be selected for a BMP before evaluating the
next BMP on the list.
Lawn and Landscaped Areas
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Post -construction
Lawn and landscape area is on till slopes greater than 33
Soil Quality
❑ percent.
and Depth
(BMP T5.13
SWMMWW Volume V,
❑ Siting and design criteria cannot be achieved on site.
Section 5.3)
List #1, #2 and #3
None of the above boxes are checked. This is the BMP that must be used for lawn and landscaped areas. On
® WorksheetA1, indicate that this will be the BMP used. CONTINUE to complete the form for other surface types
applicable to the project. If none, STOP.
Roofs
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Full Dispersion
® A 65 to 10 ratio of forested or native vegetation area to
impervious area cannot be achieved.
BMP T5.30,
SWMMWW Volume V,
A minimum forested or native vegetation flowpath length of
Section 5.3
® 100 feet (25 feet for sheet flow from a non-native pervious
surface) and protected by easement cannot be achieved.
List #1 and #2
❑Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet Al, indicate that
❑
this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none,
STOP.
Downspout Full
❑ There is an alternatie septic system on this lot or an adjacent
Infiltration
lot (mound, sand filter pressure distribution, Glendon, aerobic
treatment unit). Therefore, there is not at least 3 feet or
BMP T5
SWMMWW Vol
Volume
more of permeable soil from the proposed final grade to the
ill, Section 3.1.1
seasonal high groundwater table or other impermeable layer.
Impermeable/restrictive layer
There is not at least 1 foot or more of permeable soil from
found less than 3 feet below
List #1, #2
the proposed bottom of the infiltration system to the seasonal
grade. Perched groundwater
and #3
high groundwater table or other impermeable layer.
found less than 3 feet below
grade. 1
(10
Worksheet C
_ What's the best option for your site?
-7,5• j fl l� G �
Roofs (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Downspout Full
Infiltration
Slopes steeper than 25% or less than 200' from slope
❑
(cont.)
steeper than 40%.
BMP T5.10A,
Siting and design criteria cannot be achieved on site.
SWMMWW Volume
None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet Al, indicate that
this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none,
STOP.
Note: Criteria with setback distances are as measured from the
N/A
Bioretention or
bottom edge of the bioretention soil mix.
Rain Gardens
Citation of any of the following infeasibility criteria must be
BMP T7.30 or T5.14A
based on an evaluation of site -specific conditions and a written
SWMMWW Volume V,
recommendation from an appropriate licensed professional (e.g.,
Section 7.4
engineer, geologist, hydrogeologist):
Where professional geotechnical evaluation recommends
infiltration not be used due to reasonable concerns about
List #1 (both)
erosion, slope failure, or down -gradient flooding.
and List #2
(bioretention
Within an area whose ground water drains into an erosion
only)
hazard, or landslide hazard area.
❑ Where the only area available for siting would threaten the
safety or reliability of pre-existing underground utilities, pre-
existing underground storage tanks, pre-existing structures,
or pre-existing road or parking lot surfaces.
❑Where the only area available for siting does not allow for
a safe overflow pathway to stormwater drainage system or
private storm sewer system.
❑Where there is a lack of usable space for bioretention areas
at re -development sites, or where there is insufficient space
within the existing public right-of-way on public road projects.
❑Where infiltrating water would threaten existing below grade
basements.
ElWhere infiltrating water would threaten shoreline structures
such as bulkheads.
/
l f. Worksheet C
J
What's the best option for your site?
Roofs (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
The following criteria can be cited as reasons for infeasibility
without further justification (though some require professional
services to make the observation):
❑Within setback provided for BMP T7.30 (SWMMWW Volume
V, Section 7.4)
❑Where they are not compatible with surrounding drainage
system as determined by the county (e.g., project drains to
an existing stormwater collection system whose elevation
or location precludes connection to a properly functioning
bioretention area).
❑Where land for bioretention is within an erosion hazard, or
landslide hazard area (as defined by PAMC 15.20).
Where the site cannot be reasonably designed to locate
bioretention areas on slopes less than 8 percent.
Bioretention or
Rain Gardens
Within 50 feet from the top of slopes that are greater than 20
(cont.)
percent and over 10 feet of vertical relief.
BMP T7.30 or T5.14A
SWMMWW Volume V,
For properties with known soil or groundwater contamination
Section 7.4
(typically federal Superfund sites or state cleanup sites under
the Model Toxics Control Act [MTCA]):
• Within 100 feet of an area known to have deep soil
contamination.
• Where groundwater modeling indicates infiltration
will likely increase or change the direction of the
migration of pollutants in the groundwater.
• Wherever surface soils have been found to be
contaminated unless those soils are removed within
10 horizontal feet from the infiltration area.
El
Within 100 feet of a closed or active landfill.
❑Within 10 feet of an underground storage tank and
connecting underground pipes when the capacity of the tank
and pipe system is 1,100 gallons or less. As used in these
criteria, an underground storage tank means any tank used
to store petroleum products, chemicals, or liquid hazardous
wastes of which 10 percent or more of the storage volume
(including volume in the connecting piping system) is
beneath the ground surface.
Within 100 feet of an underground storage tank and
connecting underground pipes when the capacity of the tank
and pipe system is greater than 1 100 gallons.
Worksheet C
J
- What's the best option for your site?
.5111 T Ci �
Roofs (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
❑ Where the minimum vertical separation of 1 foot to the
seasonal high groundwater or other impermeable layer would
not be achieved below bioretention that would serve a drainag
area less than the above thresholds
❑Where field testing indicates potential bioretention/rain
garden sites have a measured (a.k.a., initial) native soil
saturated hydraulic conductivity less than 0.30 inches per
hour. A small-scale or large-scale PIT in accordance with
SWMMWW Volume III, Section 3.3.6 (or an alternative
small scale test specified by the local government) shall
be used to demonstrate infeasibility of bioretention areas.
If the measured native soil infiltration rate is less than 0.30
in/hour, bioretention/rain garden BMPs are not required
to be evaluated as an option in List #1 or List #2. In these
Bioretention or
slow draining soils, a bioretention area with an underdrain
Rain Gardens
may be used to treat pollution -generating surfaces to help
(cont.)
meet Minimum Requirement #6, Runoff Treatment. If the
underdrain is elevated within a base course of grave, it will
also provide some modest flow reduction benefit that will help
achieve Minimum Requirement #7.
Where the minimum vertical separation of 3 feet to the
®
seasonal high groundwater elevation or other impermeable
layer would not be achieved below bioretention that would
serve a drainage area that exceeds the following thresholds
(and cannot reasonably be broken down into amounts
smaller than indicated):
o 5,000 square feet of pollution -generating impervious
surface (PGIS)
o 10,000 square feet of impervious area
o 0.75 acres of lawn and landscape.
Any area where these facilities are prohibited by an approved ❑
cleanup plan under the state MTCA or Federal Superfund
Law, or an environmental covenant under Chapter 64.70
RCW.
Within 100 feet of a drinking water well, or a spring used for
drinking water supply.
i�,O N ,
Worksheet C
What's the best option for your site?
//INC
Roofs (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
Lists
N/A for this project
If needed
❑ Within 10 feet of small on -site sewage disposal drainfield,
including reserve areas, and grey water reuse systems. For
setbacks from a "large on -site sewage disposal system," see
Chapter 246-272B WAC.
None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet Al, indicate that
❑
this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none,
STOP.
Downspout
❑ For splash blocks, a vegetated flowpath at least 50 feet in
Dispersion
length from the downspout to the downstream property line,
Systems
structure, stream, wetland, slope over 15 percent, or other
impervious surface is not feasible.
BMP T5.1013
SWMMWW Volume
For trenches, a vegetated flowpath of at least 25 feet in
Section 3.1.2
❑ill,
between the outlet of the trench and any property line,
List #1, #2
structure, stream, wetland, or impervious surface is not
and #3
feasible. A vegetated flowpath of at least 50 feet between the
outlet of the trench and any slope steeper than 15 percent is
not feasible.
❑ Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for roofs. On WorksheetA1, indicate that
® this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none,
STOP.
For sites with septic systems, the only location available for
Perforated
❑ the perforated portion of the pipe is located up -gradient of
Stub -Out
the drainfield primary and reserve areas. This requirement
Connections
can be waived if site topography will clearly prohibit flows
BMP T5.10C
from intersecting the drainfield or where site conditions (soil
SWMMWW Volume
permeability, distance between systems, etc.) indicate that
III, Section 3.1.3
this is unnecessary.
There is a mound, sandfilter, Glenden or aerobic treatment
List #1, #2
device on this or an adjacent lot. Therefore, there is not at
and #3
least 1 foot of permeable soil from the proposed bottom (final
grade) of the perforated stub -out connection trench to the
highest estimated groundwater table or other impermeable
layer.
❑The
only location available for the perforated stub -out
connection is under impervious or heavily compacted soils.
❑ The only location available is on or above slopes greater than
20%
❑
Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for roofs. On Worksheet Al, indicate that
❑
this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the project. If none,
STOP.
'Worksheet C
What's the best option for your site?
Other Hard Surfaces
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Full Dispersion
® A 65 to 10 ratio of forested or native vegetation area to
impervious area cannot be achieved.
BMP T5.30
SWMMWW Volume
V, Section 5.3
A minimum forested or native vegetation flowpath length of
® g p g
100 feet (25 feet for sheet flow from a non-native pervious
List #1 and #2
surface) cannot be achieved.
Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet Al,
indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the
project. If none, STOP.
Citation of any of the following infeasibility criteria must be
based on an evaluation of site -specific conditions and a written
N/A
recommendation from an appropriate licensed professional (e.g.,
engineer, geologist, hydrogeologist):
professional geotechnical evaluation recommends
❑Where
infiltration not be used due to reasonable concerns about
erosion, slope failure, or downgradient flooding.
Permeable
Pavement
❑ Within an area whose ground water drains into an erosion
hazard, or landslide hazard area.
BMP T5.15,
SWMMWW Volume
Where infiltrating and ponded water below the new permeable
V, Section 5.3
pavement area would compromise adjacent impervious
List #1 and #2
pavements.
* Note that
❑ Where infiltrating water below a new permeable pavement
Raingardens
area would threaten existing below grade basements.
may be used
in lieu of
❑ Where infiltrating water would threaten shoreline structures
permeable
such as bulkheads.
pavement if
subject to
Down slope of steep, erosion prone areas that are likely to
List #1.
deliver sediment to the area of pervious pavement.
❑Where fill soils are used that can become unstable when
saturated.
Excessively steep slopes where water within the aggregate ❑
base layer or at the subgrade surface cannot be controlled
by detention structures and may cause erosion and structural
failure, or where surface runoff velocities may preclude
adequate infiltration at the pavement surface.
,;) f C fl,
Worksheet C
What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
❑Where permeable pavements cannot provide sufficient
strength to support heavy loads at industrial facilities such
as ports.
❑Where installation of permeable pavement would threaten
the safety or reliability of pre-existing underground utilities,
per -existing underground storage tanks, or pre-existing road
subgrades.
The following criteria can be cited as reasons for infeasibility without
further justification (though some require professional services to
make the observation):
❑Within an area designated as an erosion hazard, or
landslide hazard.
Permeable
Within 50 feet from the top of slopes that are greater than
Pavement
20 percent.
(cont.)
BMP T5.15;
❑ For properties with known soil or groundwater
swMMww voi-
contamination (typically federal Superfund sites or state
ume v, section
cleanup sites under MTCA):
5.3
Within 100 feet of an area known to have deep soil
* Note that
contamination.
Raingardens
may be used
m
Where groundwater modeling indicates infiltration
in lieu of
will likely increase or change the direction of the
permeable
migration of pollutants in the groundwater.
pavement
pavement if
subject
subject
Wherever surface soils have been found to be
List
contaminated unless those soils are removed
within 10 horizontal feet from the infiltration area.
• Any area where these facilities are prohibited by
an approved cleanup plan under the state MTCA
or Federal Superfund Law, or an environmental
covenant under Chapter 64.70 RCW.
Within 100 feet of a closed or active landfill.
❑Within 100 feet of a drinking water well, or a spring used
for drinking water supply, if the pavement is a pollution -
generating surface.
' Worksheet C
What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
—ETWithin 10 feet of a small on -site sewage disposal drainfield,
including reserve areas, and grey water reuse systems. For
setbacks from a "large on -site sewage disposal system,"
see Chapter 246-272B WAC.
❑Within 10 feet of any underground storage tank and
connecting underground pipes, regardless of tank size. As
used in these criteria, an underground storage tank means
any tank used to store petroleum products, chemicals, or
liquid hazardous wastes of which 10 percent or more of the
storage volume (including volume in the connecting piping
system) is beneath the ground surface.
❑ At multi -level parking garages, and over culverts and
bridges.
❑ Where the site design cannot avoid putting pavement
Permeable
in areas likely to have long-term excessive sediment
Pavement
deposition after construction (e.g., construction and
(cont.)
landscaping material yards).
BMP T5.15,
SWMMWW
❑ Where the site cannot reasonably be designed to have a
Volume v,
porous asphalt surface at less than 5 percent slope, or a
Section 5.3
pervious concrete surface at less than 10 percent slope, or
a permeable interlocking concrete pavement surface (where
appropriate) at less than 12 percent slope. Grid systems
* Note that
upper slope limit can range from 6 to 12 percent; check with
Raingardens
manufacturer and local supplier.
may be used
in lieu of
® Where the subgrade soils below a pollution -generating
permeable
permeable pavement (e.g., road or parking lot) do not
pavement if
meet the soil suitability criteria for providing treatment.
subject to
See soil suitability criteria for treatment in the SWMMWW
List #1.
Volume III, Section 3.3.7. Note: In these instances, the
county may approve installation of a 6 inch sand filter layer
meeting county specifications for treatment as a condition of
construction.
Where underlying soils are unsuitable for supporting traffic
loads when saturated. Soils meeting a California Bearing
Ratio of 5 percent are considered suitable for residential
access roads.
❑
Where replacing existing impervious surfaces unless the
existing surface is a non -pollution generating surface over
an outwash soil with a saturated hydraulic conductivity of 4
inches per hour or greater.
„O
Worksheet C
What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
N/A
❑Where appropriate field testing indicates soils have a
measured (a.k.a., initial) subgrade soil saturated hydraulic
conductivity less than 0.3 inches per hour. Only small-
scale PIT or large-scale PIT methods in accordance with
SWMMWW Volume III, Section 3.3.6 (or an alternative small
scale test specified by the local government) shall be used to
evaluate infeasibility of permeable pavement areas. (Note: In
these instances, unless other infeasibility restrictions apply,
roads and parking lots may be built with an underdrain,
preferably elevated within the base course, if flow control
benefits are desired.)
❑Roads that receive more than very low traffic volumes, and
areas having more than very low truck traffic. Roads with
a projected average daily traffic volume of 400 vehicles
or less are very low volume roads (AASHTO 2001) (U.S.
Department of Transportation, 2013). Areas with very low
Permeable
truck traffic volumes are roads and other areas not subject
Pavement
to through truck traffic but may receive up to weekly use by
(cont.)
utility trucks (e.g., garbage, recycling), daily school bus use,
BMP T5.15,
and multiple daily use by pick-up trucks, mail/parcel delivery
SWMMWW
trucks, and maintenance vehicles. Note: This infeasibility
Volume V,
criterion does not extend to sidewalks and other non -traffic
Section 5.3
bearing surfaces associated with the collector or arterial.
* Note that
Raingardens
At sites defined as "high -use sites” (refer to the Glossary in
may be used
the SWMMWW Volume 1).
in lieu of
permeable
In areas with "industrial activity" as identified in 40 CFR
pavement if
122.26(b)(14).
subject to
List #1.
❑ Where the risk of concentrated pollutant spills is more likely
such as gas stations, truck stops, and industrial chemical
storage sites.
❑Where routine, heavy applications of sand occur in frequent
snow zones to maintain traction during weeks of snow and
ice accumulation.
Where the seasonal high groundwater or an underlying ®
impermeable/low permeable layer would create saturated
conditions within 1 foot of the bottom of the lowest gravel
base course.
None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet Al,
indicate that this will be the BMP used. (List #1 may use Raingardens in lieu of Permeable Pavement). CONTINUE t
complete the form for other surface types applicable to the project. If none, STOP.
c,()
C -)
' Worksheet C
- What's the best option for your site?
'sttlNO,
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Note: Criteria with setback istances are as measured from the
bottom edge of the bioretention soil mix.
N/A
Citation of any of the following infeasibility criteria must be
based on an evaluation of site -specific conditions and a written
recommendation from an appropriate licensed professional (e.g.,
engineer, geologist, hydrogeologist):
Where professional geotechnical evaluation recommends
infiltration not be used due to reasonable concerns about
erosion, slope failure, or down -gradient flooding.
❑ Within an area whose ground water drains into an erosion
hazard, or landslide hazard area.
Bioretention or
Rain Gardens
Where the only area available for siting would threaten the
safety or reliability of pre-existing underground utilities, pre-
SWMMWW Volume BMP T7.30,
Volume V,
existing underground storage tanks, pre-existing structures,
Section 7.4
or pre-existing road or parking lot surfaces.
List #1 (both)
and List #2
Where the only area available for siting does not allow for
(bioretention
a safe overflow pathway to stormwater drainage system or
only)
private storm sewer system.
❑Where there is a lack of usable space for bioretention areas
at re -development sites, or where there is insufficient space
within the existing public right-of-way on public road projects.
❑Where infiltrating water would threaten existing below grade
basements.
❑Where infiltrating water would threaten shoreline structures
such as bulkheads.
The following criteria can be cited as reasons for infeasibility
without further justification (though some require professional
services to make the observation):
❑Within setback provided for BMP T7.30 (SWMMWW Volume
V, Section 7.4)
ElWhere they are not compatible with surrounding drainage
system as determined by the county (e.g., project drains to
an existing stormwater collection system whose elevation
or location precludes connection to a properly functioning
bioretention area).
l\ Cr
Worksheet C
What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
land for bioretention is within an erosion hazard, or
❑ere
landslide hazard area (as defined by PAMC 15.20).
❑Where the site cannot be reasonably designed to locate
bioretention areas on slopes less than 8 percent.
❑Within 50 feet from the top of slopes that are greater than 20
percent and over 10 feet of vertical relief.
❑For properties with known soil or groundwater contamination
(typically federal Superfund sites or state cleanup sites under
the Model Toxics Control Act [MTCA]):
• Within 100 feet of an area known to have deep soil
contamination.
Bioretention or
0 Where groundwater modeling indicates infiltration
Rain Gardens
will likely increase or change the direction of the
(coat.)
migration of pollutants in the groundwater.
• Wherever surface soils have been found to be
BMP T7.30,
contaminated unless those soils are removed within
SWMMWW Volume V,
Section 7.4
10 horizontal feet from the infiltration area.
Within 100 feet of a closed or active landfill.
Within 10 feet of an underground storage tank and
connecting underground pipes when the capacity of the tank
and pipe system is 1,100 gallons or less. As used in these
criteria, an underground storage tank means any tank used
to store petroleum products, chemicals, or liquid hazardous
wastes of which 10 percent or more of the storage volume
(including volume in the connecting piping system) is
beneath the ground surface.
100 feet of an underground storage tank and
❑Within
connecting underground pipes when the capacity of the tank
and pipe system is greater than 1,100 gallons.
Where the minimum vertical separation of 1 foot to the
seasonal high groundwater or other impermeable layer
would not be achieved below bioretention that would serve a
drainage area less than the above thresholds
�,O
i�
Worksheet C
, What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
NIA
If needed
Lists
❑erefield testing indicates potential bioretention/rain
garden sites have a measured (a.k.a., initial) native soil
saturated hydraulic conductivity less than 0.30 inches per
hour. A small-scale or large-scale PIT in accordance with
SWMMWW Volume III, Section 3.3.6 (or an alternative
small scale test specified by the local government) shall
be used to demonstrate infeasibility of bioretention areas.
If the measured native soil infiltration rate is less than 0.30
in/hour, bioretention/rain garden BMPs are not required
to be evaluated as an option in List #1 or List #2. In these
slow draining soils, a bioretention area with an underdrain
may be used to treat pollution -generating surfaces to help
meet Minimum Requirement #6, Runoff Treatment. If the
underdrain is elevated within a base course of gravel, it will
also provide some modest flow reduction benefit that will help
achieve Minimum Requirement #7.
Bioretention or
Rain Gardens
Where the minimum vertical separation of 3 feet to the
®
(cont.)
seasonal high groundwater elevation or other impermeable
layer would not be achieved below bioretention that would
SWMMWW Volume BMP T7.30,
Volume V,
serve a drainage area that exceeds the following thresholds
Section 7.4
(and cannot reasonably be broken down into amounts
smaller than indicated):
o 5,000 square feet of pollution -generating impervious
surface (PGIS)
o 10,000 square feet of impervious area
o 0.75 acres of lawn and landscape.
❑Any area where these facilities are prohibited by an approved
cleanup plan under the state MTCA or Federal Superfund
Law, or an environmental covenant under Chapter 64.70
RCW.
Within 100 feet of a drinking water well, or a spring used for
drinking water supply.
❑Within 10 feet of small on -site sewage disposal drainfield,
including reserve areas, and grey water reuse systems. For
setbacks from a "large on -site sewage disposal system," see
Chapter 246-272B WAC.
None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet Al,
indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the
project. If none, STOP.
IV,
`;~C) Cr
3.
Worksheet C
1
-� - What's the best option for your site?
Other Hard Surfaces (cont.)
BMP and
Reason why the BMP will not work on site.
Additional Comments
Applicable
If needed
Lists
Sheet Flow
❑ Positive drainage for sheet flow runoff cannot be achieved.
Dispersion
❑ Area to be dispersed (e.g., driveway, patio) cannot be graded
BMP T5.12,
to have less than a 15 percent slope.
SWMMWW Volume
V, Section 5.3
List #1, #2
For flat to moderately sloped areas, at least a 10 foot -wide
❑
and #3
vegetation buffer for dispersion of the adjacent 20 feet of
contributing surface cannot be achieved. For variably sloped
areas, at least a 25 foot vegetated flowpath between berms
cannot be achieved.
❑ Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet Al,
indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the
project. If none, STOP.
Concentrated
❑ A minimum 3 foot length of rock pad and 50 foot flowpath
Flow
OR a dispersion trench and 25 foot flowpath for every 700
Dispersion
sq. ft. of drainage area followed with applicable setbacks
cannot be achieved.
BMP T5.11,
SWMMWW Volume
More than 700 sq. ft. drainage area drains to any dispersion
V, Section 5.3
❑ device.
List #1, #2
and #3
❑ Siting and design criteria cannot be achieved on site.
None of the above boxes are checked. This is the BMP that must be used for hard surfaces. On Worksheet Al,
❑ indicate that this will be the BMP used. CONTINUE to complete the form for other surface types applicable to the
project. If none, STOP.
13
PROP. POWER LINE
PROP.
WATER
EASEMENT
WATER MAIN--�
PROP. WATER
METER &�
SUPPLY LINE
DOWNSPOUT TO
SPLASH BLOCK
(TYP.)
PROPOSED
30'x4O' SHOP
(1,200 SF)
I' I� wz
I
w Io �
U K
I I
JI I I N
WR
I \ I I I TRAN �4-9
10'x20' LEAN TO
I I
(200 SF)
F
I -
EX, BARN
(525 SF)
_ 1 o
REVISIONS
DESCRIPTION
I
LEGAL DESCRIPTION
PROP.
10' WIDE GRAVEL
I
S33 T30N R1W TX 56 PARCEL
2 OF SURVEY
DRIVEWAY
ADDITION
V16/1'116
APPROX.
325' LONG
(3,600
SF)
SITE DATA
688.960'
1
SITE ADDRESS:
155 NIGHT OWL RD, PORT TOWNSEND, WA
— _ 20' FRONT SETBACK N8T 32' 39.00"W
TAX ACCOUNT NUMBER:
001334021
-- --
_
SITE AREA:
10.31 AC
_ _ _
ZONING:
RR-20 - RURAL RESIDENTIAL
2' WIDE DRIVEWAY TRANSITION ZONE
SHEET FLOW DISPERSION
I
(SEE DETAIL 'F',
I
OWNER/APPLICANT
CIVIL ENGINEER
REF. AtA SHEET)
I
CHARLES & HEATHER SOUTHARD RACHEL A. WEINBERG, PE
155 NIGHT OWL RD
WEINBERG ENGINEERING, LLC
17 LF DISPERSION TRENCH
60' EASEMENT I
PORT TOWNSEND, WA 98368
228.217.7224
(SEE DETAIL 'E',
FOR INGRESS, EGRESS,
RACHEL®WEINBERG-ENG.COM
REF. ALA SHEET)
& UTILITIES
35- DIAMETER W/
COVERED CARPORT
(1,666 SF ROOF AF
PROP.
SEPTIC TANK
PROPOSED
15' WIDE X 13' LONG
GRAVEL ADDITION
(230 SF)
EX. 10' WIDE DRIVEWAY
(S=1.2%)
EX. SHED
(192 SF)
EX. OUTHOUSE
(18 SF)
N86' 13' 26 .1
EX. FLOW
ARROW
r(S-1 %)
,Po jtq R SOUTHARD
8, HEATHRD
CHARLEj55 NIGHT 3340)
Weinberg Engineering
A Civil Engineering Company
WEINBERG ENGINEERING, LLC
PHONE 1 228-217-7224
RACH EL@WEINBERG-ENG.COM
aKINGSTON. WA I OCEAN SPRINGS, MS
"FAR
SOILS GRADING QUANTITIES
SILT CLAY LOAM OVER CUT = 480 CY
TOTAL NEW
COARSE SANDS FILL = 480 CY
IMPERVIOUS
GRADING QUANTITIES ESTIMATED
7,271 'J
BASED ON CURRENT SITE
VEGETATION INFORMATION & ASSUMED
LOGGING OCCURRED IN 2017 EXCAVATIONS NECESSARY FOR
UNDER FPA 2615192. EXISTING PROPOSED IMPROVEMENTS.
SHEET
VEGETATION MOSTLY CONSISTS
INDEX
OF GRASS AND REGROWTH.
1. SITE PLAN
2. STORMWATER SITE PLAN
'
3. SWPPP
IMPERVIOUS SURFACES SUMMARY TABLE
NPGIS (sf)
PGIS (sf)
TOTAL (sf)
EXISTING IMPERNOUS
7351
7,455
1 819
NEW IMPERVIUU.S
3,530
TOTAL IMP. SURFACESI
4176
1 11 285
1 15 461
' ROOF IMPERVIOUS SURFACE AREAS INCLUDE ROOF
OVERHANG.
NPGIS=NON-POLLUTION GENERATING IMPERVIOUS SURFACES
0 50' 100,
(ROOF AREAS, PATIOS)
SCALE: 1' -100'
PGIS=POLLUTION GENERATING IMPERVIOUS SURFACES
(DRIVEWAYS, PARKING)
EXISTING CONDITIONS NOTE
ALL EXISTING SITE INFORMATION SHOWN
IS APPROXIMATE AND BASED ON SITE
OBSERVATIONS OR INFORMATION
AVAILABLE ON THE JEFFERSON COUNTY
GIS IMAP. NO TOPOGRAPHIC OR
—BOUNDARY SURVEY HAS BEEN PROVIDED
FOR THIS PROJECT. PROPERTY
BOUNDARY LINES ARE SHOWN PER
RECORD OF SURVEYS FOUND ON
JEFFERSON COUNTY WEBSITE,
SITE PLAN
CHARLES SOUTHARD SFR
155 NIGHT OWL RD, PORT TOWNSEND, WA 98368
PARCEL #: 001 334 021
SECTION 33, TOWNSHIP 301 N, RANGE 01 W, W M.
Know what's below.
Call two business
days before you dig.
DATE:
!r1k. W'11,,
6/27/22
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SHEET NUMBER
JOB NO.:
" ®
22006
1
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