HomeMy WebLinkAboutBLD2021-00050 - 05 STORMWATER PLANDescribe both existing and proposed site conditions for the following items as applicable in the space below each
bullet point. Attach additional pages if needed.
structpres
Ale)..3 ba Rtykiel norme. Q041
roads
no m0.1
septic am:itilla locations and type
011/4 Jr m
l sys-ten locce.e_el otts-11) ho
stormg er run- neigh n g properties
utility locations
potaer 1)01c CS toCA:Fr 6 o1 /4:Ir 40e-S+ RAS, WIll'il.eS QM 94, eaf
weilhead Locations i
A
expected excavation depths and volumes
A k- •Nbk-eibs1 01 5 Gtifit- icaks- Cl'. expec a work to e aone in iliciht-of-w m a Ku
Worksheet Al
Medium & Large Project Report
Minimum Requirement # 1 : Preparation of Stormwater Site Plan
C of,lete the following:
Submit a site plan demonstrating the project. Refer to REFERENCE AlA 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.
A
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 BlA includes
dia ams of common BMP's that may be used on the site plan.
R 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 (SERs); however, ways to minimize pollution from moving
downstream should be consideeed 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
Feb 01 2021
Feb 01 2022
Worksheet Al
Medium & Large Project Report
Minimum Requirement #3 : Source Control of Pollution (continued from page 1)
Ch ck 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 con 'clering operational and structural measures to prevent
stormwater from coming in contact with pollutants, I hav
p determined this MR to not be applicable. made appropriate adjustments to my project.
D 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:
n 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
Feb 01 2021
Worksheet Al
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 pdon 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.
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
Feb 01 2021
Worksheet Al
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:
fl My project is located in a drainage subbasin that
drains to directly or indirectly to freshwater.
PROCEED to Page 5 to use LIST #1.
My Project will discharge to a subasin draining to
salt water, Dosewallips River, or Hoh River.
PROCEED to Page 6 to use 1.!S
fl 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
Feb 01 2021
Worksheet Al
Medium St Large Project Report
veti N o
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 ion 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:
4ary A: Lawn and Landscape A
My project does not have disturbed soils not covered by impervious
surfaces.
n 5. Each BMP above is infeasible, see WORKSHEET C. STOP.
COMPLETE AND SUBMIT WORKSHEET Bl. 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
111 My project does not have Other Hard Surface areas
Li 1. Full dispersion (BMP T5.30)
2. Permeable Pavement (BMP T5.15)
OR
Rain Garden (LARGE PROJECTS CANNOT USE) (BMP 15.14A)
3. Sheet Flow Dispersion (BMP 15.12)
OR
Concentrated Flow Dispersion (BMP T5.11)
4. Each item above is infeasible, see WORKSHEET C. STOP.
COMPLETE AND SUBMIT WORKSHEET Bl. NO OTHER
INFORMATION REQUIRED AT THIS TIME.
L11. Post-Construction Soil Quality and Depth
Disturbed soils shall be amended (BMP T5.13: ).
Category B: Roofs
fl My project does not have Roof areas.
E 1. Full Dispersion (BMP T5.30)
OR
Downspout Full Infiltration (BMP T5.10A)
Fi 2. Rain Garden (LARGE PROJECTS CANNOT USE)
(BMP T5.14A)
Downspout Dispersion System (BMP T5.10B)
4. Perforated Stub-Out Connection (BMP T5.10)
Feb 01 2021
El 74 E
Construction Protection: Medium and Large Projects
(SWPPP:Stormwater Pollution Prevention Plan)
Worksheet B1
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 BlA 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:
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.1_92.Entfer_ E Ho visibility
D 0.01 Preserving Natural El
Zones Fence
YegetatiOn
fl 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.
D 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.
Ch ose one of the following:
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 0 ci 0(2 wiicti_ LII c107 Cons' ruction
Construction Entrance / Wash Road / Pa rkingAresr
Exit Stabilization
page 1 of 6
Feb 01 2021
oN
Worksheet B1.
Construction Protection: Medium and Large Projects
(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):
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.
Ei The site has already been stabilized and re-vegetated.
D Sediment control BMPs shall be placed at the locations shown on the SWPPP Site Plan. If this option is selected
E C235 Wattles
C232 Gravel Filter C;234 Vegetated
Berm Strip
Element 5: Stabilize Soils
The goal of this element is to stabilize exposed and unworked soils by implementing erosion control BMPs.
Se ect 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.
Ell This element does not apply to my project because:
LI
My project must implement specific BMP's to ensure compliance. (Check BMP's you will use on the next page).
check the BMPS you will use below:
E C231 Brush Barrier C233 Silt Fence
page 2 of 6
Feb 01 2021Feb 01 2021
Worksheet B1
Construction Protection: Medium and Large Projects
(SWPPP:Stormwater Pollution Prevention Plan)
n C120 Temporary & C122 Nets & Blankets C124 sodding CI31 Gradient
Permanent_Seeciling Terraces
C121 Mulching 3 Plastic Coverim:,, C125 Topsoil / nt Dust control
Composting
7 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.
Se! ct one of the two statements applicable to the project.
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 1foot vertical. Therefore, there is no requirement for additional
engineered slope protection.
fl 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 n C205 Subsurface C207 Check Dams
Seeding Drains
111 C204 Pipe Slope Drains n C206 Level Spreader 7 C208 Triangular Silt Dike
Lccolextile-lincased 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.
N
elect 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.
D 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:
7 C220 Storm Drain Inlet Protection
There are no catch basins on or near the site.
page 3 of 6
Feb 01 2021
oN
Worksheet 81
Construction Protection: Medium and Large Projects
(SWPPP: Stormwater Pollution Prevention Plan)
1/IN
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 outfails and conveyance systems.
Sel ct one of the three statements applicable to the project.
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:
fl C202 Channel Lining 7 C207 Check Dams n C209 Outlet Protection 7 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.
_I There will be no concrete work,
rift here here will be no sawcutting work,
There will be no hazardous materials on-site,
There will be no fertilizer or pesticide application,
There will be no heavy equipment associated with this project,
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 C1.51. C1.54. If this option is selected check the BMPS you will use below:
C151 Concrete Handling
CI53 Material Delivery, Storage, and Containment
D cl5Z S4Wc: Su rticjng
Pollution Prevention
C154 Concrete Washout Area
page 4 of 6
Feb 01 2021
Worksheet B1
Construction Protection: Mie.diunand Large Projects
(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)
sep rately from stormwater.
Sel ct 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: n C203 Water Bars C2,3 ... Vegeta teci_Filtration c2p. gni Spret4(14.
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.
E._. De cribe the steps you will take:
Best Management Practices or BMPs shall be inspected and maintained during construction and removed within
30 days after the County Inspector or determines that the site is stabilized, provided that they may be 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
Feb 01 2021
002 Buffer Zone
C233 Silt Fence
C231 Brush Barrier
fl CaVisibility Fence
n C234 Vegetated Strip
ri Other
Worksheet 31
Construction Protection: 11/lediur
(SWPPP:Stormwater Pollution Prevention Plan)
nd Large Projects
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.
Me hods that will be used to protect permanent stormwater management BMPs include:
Lg Sequencing the construction in a fashion to install these permanent BMPs at the latter part of the
construction grading operations,
D Excluding equipment from the BMPs and the associated areas,
D 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:
Applicant or Representative Signature
pai;e. 6 of 6
Feb 01 2021