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HomeMy WebLinkAboutStormwater Site Plan for FPA2006-00020 - FPA Storm Water Plan - 12/6/2007 MASON COUNTY PUBLIC WORKS DIRECTOR/COUNTY ROAD ENGINEER Shelton, Washington 98584 DATE: December 6, 2007 INTER-DEPARTMENTAL COMMUNICATIONS TO: Michael MacSems PARCEL # 32134-23-00020, 321343100000, 32134-24-00020, 32134-31-00020, 32134-32-00000 FROM: John Sliva, Programs Engineer-PW PERMIT NUMBER: FPA2006-00020 SUBJECT: Stormwater Site Plan NAME: Keith Schouviller Michael The proposed timber thinning plan has been received and reviewed by Public Works. A review of the timber harvest plan shows approximately 10 acres to be thinned. The plan does not address stormwater runoff. No erosion and sediment control (ESC) plan was submitted. The geological assessment does recommend some erosion control measures. Mason County Code Title 14 Buildings and Construction Chapter Section 14.48.140 states that Non residential development exceeding 5000 square feet of impervious surfacing, and land disturbing activities of one acre or more must have the large parcel Erosion and Control Plan (if required) and the permanent stormwater quality control (PSQC) plan (if required) prepared and stamped by a licensed civil engineer. More than one acre of land disturbing activity will take place with the thinning of trees. I recommend that a Stormwater Site Plan be developed which conforms to the Chapter 14.481401 (A) of the Mason County Code and the 1992 Department of Ecology Stormwater Manual for the Puget Sound Basin. The SSP must be by a licensed civil engineer in the State of Washington. 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 724 if you have any questions regarding these comments, or if you feel any features need further discussion or attention. Si c rel , Jo n Siva rograms Engineer Keith Schouviller Site Management Plan and Map 1 . Unite 1 , less than . 5 acres . is marked by Timber Harvest Flagging . Unit #2 - Harvest boundaries are shown on the map. The north line is a five year old clearcut with flagging. The east line is marked with Timber Harvest Boundary flagging , while the southwest line is access road with Timber Harvest flagging . Since the stand is being thinned. all residual trees are retention trees . 2 . See Map . old shed and barn on east side of Unit #1 . 3 . Major skid trail is located on map with landing in the northwest corner of -property . There are no proposed streets . Access for logging truck directly on to East Mason Lake County road NW corner of project . 4 . There is no scheduled ft.ttUre land development . The operation is a commercial thinning with a 40 % harvest of the understory and removal of some larger trees because of damage or spacing- reasons . A wetlands or so called lake is over 350 feet to the east . No btiffer required. To the east of the timber sale boundary is a seasonal . rtrnoff area that only tinder the heaviest of 24 hour storms collects water . As stated in the geotech assessment dated March 19 . 2007 by David C. .Strong, the water infiltrates the permeable outwash sands and gravels and shows up east in the seasonal runoff . There is no signs of any water ever being present on the surface in any form. Visiting the area on March 24. 2007 after 1 . 75 inches of rain (over 24 hours) and a total of 3 inches for the previous week , there wasn ' t standing water in the timber sale area. A small amount showed up in seasonal runoff area to the east . 5. Site topography contours at 20' . Mason County' s GIS only shows 20' contours. 6 . N/A 7 . There will be no drainage ways or culverts . Main skid trail will have water bars upon completion and seeded. 8. There are no plans of future harvesting or development under present ownership . Only if timber stand is damaged because of wind, ice or others would there be a another harvest . 9. Scale on map is 1 " = 172 feet . Using the Mason County GSI ' s Map Mason Map Viewer this is the best I can do. 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