HomeMy WebLinkAboutBLD2020-00225-3 Sonya Baumstein Stormwater Plan 6-30-2020Sheet 1 of 2
Stormwater Site Plan
Drawn By:
Everett A. Sorensen, PE
Evergreen Engineering
715 Grant Street
Port Townsend, WA 98368-2405
ev_sorensen@hotmail.com
360-821-9960
June 29, 2020
Sonya Baumstein’s Property
522 McMinn Road
Port Townsend, WA 98368
Jefferson County Parcel 001063018
222,600 SF (5.11 acres)
Previous Cases: BLD20 -00225
SEP19 -00004
200 300100 400 Ft0
Actual Size (11 "x17 "): 1 inch = 100 Ft
Proposed ≤4' Tall Dry-Stack
Rock Retaining Wall
Ex. Well
Survey Pin Survey Pin
Subject Parcel consists
of two segments divided
by McMinn Rd
Existing Driveway
approximate route
Ex. Shed
Proposed 40' x 90' (3,600 SF) Pre-Fab Metal Building
Roof to discharge onto concrete perimeter sidewalks
Existing Electric
Transformer Approx.
Position
Existing 1,000 Gal
Septic Tank
SEP19-00004
Existing Gravity-
Discharge Drainfield
Existing Cleared Building Site
Ex. Electric Supply
D-Box Proposed Perimeter Sidewalks (2,450 SF)
Existing Gravel Parking
Existing Vegetated Surfaces
Maintained for Run-Off Treatment
Anticipated Stormwater
Surface Sheet Flow Paths
453'
~160'
Sheet 2 of 2
Minimum Stormwater Requirements 1-9
Construction SWPPP and
Temporary Erosion & Sedimentation Controls
Drawn By: Everett A. Sorensen, PE
Evergreen Engineering
715 Grant Street; Port Townsend , WA 98368-2405
ev _sorensen @hotmail.com 360-821-9960
June 29 , 2020
Minimum Stormwater Requirements 1 – 9 from the Department of Ecology’s Stormwater Management Manual for Western Washington
Minimum Requirement (MR) #1: Preparation of Stormwater Site Plans (contained herein)
MR #2: Construction Stormwater Pollution Prevention and Temporary Erosion & Sediment Controls
Element 1: Preserve Vegetation/Mark Clearing Limits prior to clearing topsoil and vegetation — No additional clearing is required at subject site.
Element 2: Establish Construction Access The existing driveway with a base of quarry spalls will provide vehicle access for all stages of construction . Construction
vehicles shall be free of excess mud upon leaving site.
Element 3: Control Flow Rates – There are no existing concentrated surface flows at the site. Stormwater run-off shall remain dispersed along the length of existing
driveway and building site. These disperse discharges will flow through vegetated surfaces within the subject parcel .
Element 4: Install Sediment Controls -- If additional surfaces are disturbed during construction, install a surface sod berm silt barrier or silt fence downhill of the area.
Element 5: Stabilize Soils -- Stabilize temporarily exposed soils by hand-watering and establishing living cover with grass and ground -covering vegetation as quickly as
possible. Hand-water soil piles as needed during dry season . Divert stormwater discharges away from soil piles during wet season
Element 6: Protect Slopes -- Not applicable for this site.
Element 7: Protect Drain Inlets -- There are no nearby stormwater drain inlets or catch basins needing protection.
Element 8: Stabilize Channels and Outlets -- Not applicable for this site.
Element 9: Control Pollutants -- Prevent discharge or release of all pollutants, including motor oil and construction debris. Instruct all personnel as to this policy.
Element 10: Control De-Watering -- Not applicable for this site; no dewatering expected.
Element 11: Maintain BMPs -- All Temporary Erosion & Sedimentation Control Features must be inspected regularly, and maintained & repaired as needed.
Element 12: Manage The Project -- Assess conditions regularly and adjust construction stormwater management features as needed .
Element 13: Protect Low Impact Development BMPs -- Avoid unnecessary ground disturbances.
MR #3: Source Control of Pollution -- Prevent discharge or release of all pollutants, including motor oil and construction debris. Instruct all personnel as to this policy.
After construction is completed, all unsurfaced ground shall be landscaped with vegetation and/or rockery. Parking areas shall be maintained by immediately cleaning
any releases of oil, other hydrocarbons or chemicals and by collecting debris regularly .
MR #4: Preservation of Natural Drainage Systems and Outfalls — Not applicable for this site.
MR #5: On -site Stormwater Management — disperse and infiltrate stormwater on-site to the maximum practical extent.
MR #6: Runoff Treatment -- Runoff from all impervious surfaces will be naturally treated as it flows through existing vegetated surfaces.
MR #7: Flow Control – Control of stormwater flow shall be achieved by routing run-off through existing vegetated surfaces which will dampen sheet flow.
MR #8: Wetlands Protection -- Not applicable for this site.
MR #9: Operations and Maintenance — Maintain native vegetation in order to provide stormwater flow attenuation and natural treatment.
Baumstein Stormwater Management Plan, 522 McMinn Rd; Port Townsend, WA 98368
Proposed large residential construction project with ample native forest to be preserved
≥40-ft wide native forest vegetated buffers adjacent to all proposed impervious surfaces will receive dispersed stormwater run -off for natural flow
attenuation and treatment
Proposed structure to discharge roof run -off onto perimeter sidewalk in order to disperse stormwater
Stormwater flow control strategy in substantial compliance with Washington Department of Ecology’s Stormwater Management Manual for Western
Washington’s Best Management Practice BMP T5.12: Sheet Flow Dispersion (Volume V – Runoff Treatment BMPs – December 2014 , page 5-6)
For any impervious or pervious surface that is graded to avoid concentrating flows
Dispersed flows traverse a narrow band of adjacent vegetation for effective attenuation and treatment.
For flat or moderately sloping (< 15% slope) surfaces such as driveways,...patios, roofs without gutters, lawns,
Provide a 2-foot-wide transition zone to discourage channeling between the edge of the impervious surface (or building eaves) and the
downslope vegetation. This transition zone may consist of an extension of subgrade material (crushed rock),
Provide a 10-foot-wide vegetated buffer for up to 20 feet of width of impervious surface. Provide an additional 10 feet of vegetated buffer width
for each additional 20 feet of impervious surface width or fraction thereof (ie . – 40 ft wide impervious surface would require at least a 20 ft wide
vegetated buffer).
Sonya Baumstein’s Property
522 McMinn Road; Port Townsend, WA 98368
Jefferson County Parcel 001063018
222,600 SF (5.11 acres)
Previous Cases: BLD20 -00225 SEP19 -00004