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HomeMy WebLinkAboutMLA16-00029 - FPA16-00002 Jablonski Stormwater PlanSTORMWATER SITE Parcel # 821333018 Paula J. and Ronald W. Jablonski, Jr. PROJECT OVERVIEW �r (uv r MAP 2 4 2016 D J DEPT n r i .I " ,. -'r . 1. Describe the proposed developed conditions of the site. Indicate position and relative size of proposed improvements on the site map. The developed site conditions will include approximately 650 square feet of driveway, 1800 square feet of parking surface, 2600 square feet of home, 1200 square feet of attached garage, 300 square feet of patio, for an estimated total 6550 square feet of impervious surface upon the completion of development. These developments will be concentrated at the north end of the property, which is the highest elevation of the property. EXISTING CONDITIONS SUMMARY 2. Describe the existing topography. Indicate contours on the site map. The property is at the south end of a long plateau, and slopes downhill on the south, east and west sides. From the highest point on the property (200' elevation) westerly to Teal Lake Road the slope averages 22%. From the same point to the easterly property boundary the slope averages 27%. From the same point southeast to the arrowhead point near Hwy 104 the slope averages 20%, though from the highest point on the property to 150' elevation the slope is 14%, with a steeper 29% slope from 150' to the property boundary. 3. Describe the existing vegetation. Indicate native vegetation areas on the site map. This property was logged in January 2016, so there is very little vegetation left on the property but a consistent layer of logging slash approximately 12" deep exists across the property. The trees that remain are primarily Douglas fir, hemlock, and a few small hardwoods. The arrowhead point of the property (SW corner) has an understory of Himalayan blackberry, Oregon grape, devil's club, holly, and salal. From the high point of the property, looking south • There are no significant geographic features on this parcel. • The DNR stream identified by Jefferson County does not exist. (see letter from DNR officer Ross Goodwin dated 2/26/2016). • The entire parcel is identified by Jefferson County, WA as having "slight landslide hazard." Per the attached Geotechnical Report ... • The entire parcel is identified as having an aquifer recharge rating of SUSC. • The entire parcel is identified as a high risk seawater intrusion protection zone. • The entire parcel has a shoreline slope stability rating of "unstable." 8. Describe the general vicinity of the site, including adjacent land uses and structures, utilities, roads, and sensitivelcritical areas (streams, wetlands, lakes, steep slopes, etc.). This is a triangular-shaped parcel. The south border is shared with the easement for Hwy 104. The west border is shared with the easement for Teal Lake Road. The east border is adjacent to three residential parcels, two of which are included in the adjacent subdivision and one that is zoned ` mral residential." PERMANENT STORMWATER CONTROL PLAN This portion of the Stormwater Site Plan consists of the selection and installation of the appropriate stormwater control BMPs and facilities to remain in place after construction of the project is completed. 9. Describe the developed site hydrology, as proposed. Indicate whether stormwater will be fully dispersed (i.e., per BMP T5.30 in the Manual) or, if not, what types of stormwater flow control will be utilized for the site or specific threshold discharge areas within the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities. o There are currently no facilities on the site, save a rock driveway. All other facilities are "proposed." o Rain water from the proposed facilities will be diverted into a collection tank for stormwater management. o Approximately 6550 square feet of impervious development are proposed within 1 acre (43,560 square feet). The remaining square footage will maintain the characteristics of the site soils, resulting in full dispersal of rain water. 10. If the project requires the use of stormwater treatment facilities, describe the types of stormwater treatment facilities proposed for use on the site. Locate these facilities on the site plan and differentiate proposed facilities from existing facilities. o This project does not require stormwater treatment facilities. 11. Describe the performance goals and standards applicable to the project. 12. Describe the flow control system. o Gutter/downspout system into a rain collection tank. 13. Describe the water quality system. o Gutter/downspout and rain collection tank on developed site; full dispersal through soils on remainder of property. 14. Describe the conveyance system analysis and design. o In general, the typical residential gutter/downspout system to a collection tank will be utilized. The collection tank will be configured so as to allow the rain water to be used for irrigation. The logging slash and emerging vegetation enhance the soil's natural absorption capabilities. Soil stability is not an issue (ref: GeoTech survey) L Protect Slopes Slopes are stable, the soils across the property provide full dispersal of rain water. Logging slash, distributed across the property, provides additional storm water dispersal. g. Protect Drain Inlets None present. h. Stabilize Channels and Outlets None present. i. Control Pollutants All construction debris will controlled and contained at the home construction site. j. Control De -Watering There is no below -ground excavation planned with the construction of this home. The home will be constructed on a concrete slab. k. Maintain Best Management Practices There is not an anticipated need for additional temporary rain water control measures. Existing soil properties, logging slash, and vegetation are expected to provide adequate control. Should the need arise for additional measures (such as straw waddles), they will be put into place for the duration of construction. 1. Manage the Project We are utilizing a highly experienced local General Contractor to plan and implement the project. He is experienced in all aspects of project development and management, is familiar with Jefferson County's BMPs, and employs local Subject Matter Experts for technical expertise and project development. m. Protect Low -Impact Development BMPs N/A 2. Adjacent Areas Description of the adjacent areas that may be affected by site disturbance. o None. Description of the downstream drainage path leading from the site to the receiving body of water. o The property slopes downward to Teal Lake Road and/or Hwy 104. No surface water runs off of the property; all of the rain water is absorbed into the soil. 3. Environmentally Sensitive Areas Description of environmentally sensitive areas that are on or adjacent to the site. o None. Description of special requirements for working in or new environmentally sensitive areas. o N/A 4. Erosion Problem Areas APPLICANT SIGNATURE By signing the Construction SWPPP worksheet, I as the applicant/owner attest that the information provided herein is true and correct to the best of my knowledge. I also certify that this application is eing made with the full knowledge and consent of all owners of the affected property. MAi%