HomeMy WebLinkAboutCOM2021-00006 Stormwater Site Plan - COM Permit / Conditions - 3/4/2021 MASON COUNTY
PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER
3 Shelton, Washington 98584
N fu0
DATE: March 2, 2021
INTER-DEPARTMENTAL COMMUNICATIONS
TO: Trish Woolett PARCEL # 42004-10-00000 / 24-00000
FROM: Fred Perryman — E&C Asst manager PERMIT #: COM2021-00006
SUBJECT: Stormwater Site Plan (SSP) NAME: Ridge Motorsports Park
Trish:
The stormwater site plan and narrative for Ridge Motorsports Park off of Eels Hill Rd was received
and reviewed by Public Works.
The plan notes the building will add 4,800 square feet of new impervious surfaces. The permanent
stormwater facilities include a series of catch basins that will convey the stormwater to a pond
and grass swales.
The stormwater plan is considered acceptable.
Permit Conditions:
• A Declaration of Covenants Associated with Privately Maintained Storm Drainage Facilities
(O&M) should be executed and recorded with Mason County prior to permit being finalized.
• The stormwater drainage plan should be incorporated into the site-plans and be a condition
of permit issuance.
• Record drawings shall be drawn and recorded with the county at the completion of the
project
Adequate erosion and sediment control features need to be implemented during land disturbing
activities to protect neighboring properties and State waters from adverse stormwater runoff
impacts. The migration or release of silty water or mud from the applicant's property will be
considered a violation of County and State water quality protection regulations.
Please feel free to contact me at 625 if you have any questions.
Since ly,
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To: Fred Perryman
From: Bob Balmelli PE
CC: Project File,Client via email
Date: 3.2.21
Re: RBE No. 14050—Ridge Motorsports Park Hot Pit Garages
Project Summary
This following information is in support of the above referenced project.The existing storm system in place will
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ait and e ontrol for the addition of the new roof runoff from the proposed hot pit garages.
elli PE
Enclosures: Drainage Site Map
32107
91 SW 13th Street - Chehalis,WA 98532 - Office (360)740-8919 - Email Civilpros@RBEngineers.com
Page 2 of 3
Project Data Summary
Property Owner: Ridge Motorsport Park
1060 W. Ells Hill Road
Shelton, WA 98584
(360)427-7223
Parcel No.: 42004-24-00000,42004-10-00000,42004-14-00000
Sec/Twn/Rng: Section 4,Twn. 20N, Rng 4W
New Building Size: 2—30'x 60' buildings
Grading: 120 CY
Project Modeling Area Summary
The project includes construction of two new 30 x 60 hot pit garages.The roof runoff from the buildings
will be tight lined to the existing storm line east of the buildings via a 6"smooth walled PVC pipe at min.
0.5% slope.
Temporary Sediment & Erosion Control
The project limits currently consist of gravel in the new building area. Minimal erosion control will be
needed to control sediment during construction. Below the list of elements for the TESC plan.
Element 1: Mark Clearing Limits
• Prior to beginning land disturbing activities, including clearing and grading, clearly mark all
clearing limits for the work to be performed.There are no critical areas to protect for this project.
Element 2: Establish Construction Access
• Construct
ion vehicle access
will utilize paved sur
faces.rfaces. No exposed soils will be driven in by
construction vehicles and construction entrance should not be needed.
Element 3: Control Flow Rates
• There will be no increases in the volume,velocity, and peak flow rate of stormwater runoff from
the new roof area and asphalt surrounding the new buildings. The existing paved paddock area
has a capture and conveyance system to collect runoff from the new asphalt area. This runoff
will be discharged to the water quality infiltration swale along the southern property limits. Roof
runoff will be tight lined to a nearby storm line that feeds into the water quality infiltration swale.
Element 4: Install Sediment Controls
• BMPs intended to trap sediment include catch basin silt sacks inserts. Not other se
diment
controls are needed for this project.
Element 5: Stabilize Soils
• All adjacent exposed excavations around the building will be paved, so there are no exposed
soils remaining upon completion of the project.
• From October 1 through April 30, no soils shall remain exposed and unworked for more than 2
days. From May 1 to September 30, no soils shall remain exposed and unworked for more than
7 days. This stabilization requirement applies to all soils on site, whether at final grade or not.
91 SW 131h Street - Chehalis, WA 98532 - Office(360) 740-8919 - Email Civilpros@RBEngineers.com
Page 3 of 3
These time limits may be adjusted by the local permitting authority if it can be shown that the
from May 1 to September 30, no soils shall remain exposed and unworked for more than 7 days.
Element 6: Protect Slopes
• There are no cut and fill slopes associated with this project.The site limits are flat.
Element 7: Protect Drain Inlets
• Storm drain inlets operable during construction shall be protected so that stormwater runoff does
not enter the conveyance system without first being filtered or treated to remove sediment.
Element 8: Stabilize Channels and Outlets
• No channels or outlets are being constructed for this project. Element does not apply.
Element 9: Control Pollutants
• All pollutants, including waste materials and demolition debris, that occur on site during
construction shall be handled and disposed of in a manner that does not cause contamination of
stormwater. Concrete cleanout will be completed at the designated wash out area as shown on
the plans.
Element 10: Control De-Watering
• No de-watering will be necessary for this project. Soils are well draining.
Element 11: Maintain BMPs
• Temporary and permanent erosion and sediment control BMPs shall be maintained and repaired
as needed to assure continued performance of their intended function. Maintenance and repair
shall be conducted in accordance with BMPs.
• Sediment control BMPs shall be inspected weekly or after a runoff-producing storm event during
the dry season and daily during the wet season. The inspection frequency for stabilized, inactive
sites shall be determined by the local permitting authority based on the level of soil stability and
potential for adverse environmental impacts.
Element 12: Manage the Project
• Proposed erosion and sediment control measures.The proposed project limits are almost
completely surrounded by paved surfaces. Project erosion and sediment control inspections and
maintenance will consist of cleaning catch basin insert and sweeping any sediment from the
surrounding paved surfaces.
91 SW 131h Street - Chehalis, WA 98532 - Office(360)740-8919 - Email Civilpros@RBEngineers.com