12815 19TH AVE SE 2022-05-06 - Laserfiche WebLink

Roof downspouts at each corner of the portable buildings will discharge to the gravel infiltration facility. PROPOSED PROJECT LIMITS LAND COVER Gravel Infiltration Bed: 2,817 square feet Roof 1,774 square feet (over top infiltration bed) Asphalt Path: 437 square feet Total Area: 3,254 square feet PROPOSED RUNOFF Proposed flow frequency rates from WWHM 2012 (Appendix B): 2 year 0 cfs 10 year 0 cfs 50 year 0 cfs 100 year 0 cfs MINIMUM REQUIREMENT #2: SWPPP A Stormwater Management Plan, including Temporary Erosion and Sedimentation Control BMPs, is included in Appendix A. Stormwater Pollution Prevention Plan elements are described below. Element #1: Preserve Vegetation/Mark Clearing Limits The project site is surrounded by lawn. Only lawn within the construction foot print will be removed. Limits of construction will be marked with silt fence or straw on the downslope side and by surveyor's tape, cones, paint or temporary fencing, or other methods on the upslope side. Element #2: Establish Construction Access Access to the site will be through lawn from an asphalt parking lot. Due to the small area of disturbed soils, there is not room to install a gravel construction entrance within the disturbed site area. Due to the low square footage of the disturbed site, construction equipment will operate from the lawn area and traverse the lawn to enter and exit the site. Element #3: Control Flow Rates Stormwater from this project will be infiltrated. Gravel building pads will be placed at the beginning of construction and will serve as infiltration facilities during and after construction. No temporary facilities are proposed. Element #4: Install Sediment Controls Silt fence will be installed on the downslope side of the project before the existing lawn is removed for the gravel building pads. The disturbed site will be stabilized by the gravel building pads within a few days of lawn removal. Stormwater Site Plan, Including SWPPP 5 Silver Lake Elementary School Portables