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Home My WebLink AboutCOM2021-00007 Stormwater Site Plan - COM Permit / Conditions - 3/4/2021 MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER Shelton, Washington 98584 H DATE: March 2, 2021 INTER-DEPARTMENTAL COMMUNICATIONS TO: Trish Woolett PARCEL # 42004-10-00000 / 24-00000 FROM: Fred Perryman — E&C Asst manager PERMIT #: COM2021-00007 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. Sincerely, _------- APPROVED AS SUBMITTED REVISE/RESUBMIT red Perry an� REJECTED Eng. & Const Asst Manager APPROVED W/ REVISIONS SHOWN BY: DATE:3L4 �oZ Engineering DESIGN -3 PERMIT -3 MANAGE Technical Memo 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 X alfi and ontrol for the addition of the new roof runoff from the proposed hot pit garages. elli PE Enclosures: Drainage Site Map wit W��t�F 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 • Construction vehicle access will utilize paved surfaces. 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 sediment 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 3. Characteristics of the Area. The area is characterized as forest land and rural 1 properties with low density residential and commercial forestry uses. A County solid 2 waste transfer station is located across Eelss Hill Road. The property is zoned Rural Residential-20. 3 4. SEPA Review. Pursuant to Title 8 MCC (Environmental Policies) a 4 Determination of Nonsignificance (DNS) was issued on July 14, 2010 for the purpose of considering the release of the forest practices moratorium. No SEPA appeal was 5 filed. (Exhibit H) The Staff s review of the site found that it is generally flat with a 6 bench and slope of 44%. There were no critical areas on the site besides the steep slope. A review of the site under the County's critical areas regulations, geotechnical 7 review and stormwater and erosion control plan revealed no instability issues and found that the proposal met the County's requirements. (Exhibit 1-Staff Report; 8 Exhibit H). During the comment period, WDFW notified the County of the existence of the Mazama Pocket Gophers on the site. Although the gophers are not listed under 9 the Federal Endangered Species Act, they are listed as a priority species by the 10 WDFW (as "threatened" due to habitat loss). In response, the applicant has hired a biologist and will propose a protection and habitat mitigation plan for the Mazama 11 Pocket Gophers. Additional SEPA review may be required for other permits, approvals or rezones where required by the County Code. 12 5. Development Re atii luirements of 13 SEPA, the application is /' ►.040 (Forest 14 Practices Act), MCC 15.01. —J��n) ;C 11.04.130 (Moratorium Release crite r(�' ;h applicable 15 County regulation as desc s 15 r ram �r�' N° . 2-4). The Examiner finds that the st a d application 16 against the criteria set fort S ��f lh Staff Report (Exhibit 1 is therefore ad p 17 ) d v �, �.�,�- erein by this reference as if set forth in fi h V ''`dy application's 18 compliance with the Forest 19 20 1. Procedural: 21 A. The Hearing Examiner is authorized to review this application for the release of a 22 forest practices moratorium pursuant to MCC 11.04.130 and MCC 15.03.050. 23 B., Notice of the application was properly given under the Mason County Code. 24 C. The requirements of SEPA, including public notice and an opportunity to comment 25 have been met in this case. No appeal was filed. D. The Hearing Examiner concludes that the consideration of the release of the moratorium is a condition-precedent to a landowner's ability to apply for a rezone pursuant to MCC 17.05.080. Manke Timber Company-VAR 2010-00005 Release of Forest Practices Moratorium p.4 Findings,Conclusions and Decision