Laserfiche WebLink
BMP and <br />Infeasibility description <br />applicable lists <br />Infeasibility criteria <br />and rationale for each <br />BMP not selected <br />T514A <br />The following criteria can becited as reasons for infeasibility without <br />Infl ltration BMPS <br />Bioretention <br />furtherjustification(though some require professional services to <br />or Rain Gardens <br />make the observation): <br />are not <br />(continued) <br />EI Within 100 factor an underground storagetankand connecting <br />recommended, <br />underground pipes when the capacity of the tank and pipe system <br />see Previous <br />is greater than 1,100 gallons. <br />Comments. <br />❑ Where field testing indicates poterdial bioretention/rain garden <br />sites have a measured(a.k.a., intual) native soil saturated <br />hydraulic conductivity less than 0.30 inches per hour. A small-scale <br />or largescale PIT in accordance with SWMMWW, Section V 5A <br />shall be used to demonstrate infeasibility of bioretention areas. If <br />the measured native soil infiltration rate is less than 0.30 in/hour, <br />bioretention/rain garden BMPS are not required to be evaluated as <br />an option In List pt or List Al <br />Where the minimum vertical separation of 3 feet to the seasonal <br />high groundwater elevation or other impermeable layer would not <br />be achieved below bioretention that would serve a drainage area <br />that exceeds the following thresholds(and cannot reasonably be <br />broken down into amounts smaller than Indicated): <br />• 5,000 square feet of pollution generating impervious <br />surface(PGIS) <br />• 10,000 square feet of impervious area <br />• 0J5 acres of lawn and landscape. <br />❑ Wherethe minimum vertical separation of l foot to the seasonal <br />high groundwater, Hardpan layer, or other impermeable layer would <br />not be achieved below hioreterdion that would serve a drainage <br />area less than the above thresholds. <br />❑ Within 100 feet of a drinking water well, or a spring used for <br />drinking water supply. <br />❑ Within 10 feet of small on site sewage disposal drain0eld, <br />including reserve areas, and grey water reuse systems. For <br />setbacks from a°large on site sewage disposal system,"see <br />Chapter 246272B WAC. <br />City of Everett Public Works <br />Small Project Stormwater Site Plan Report Dan 2019 <br />