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BMP and Infeasibility description applicable lisp Infeasibility criteria and rationale for each BMP not selected T5.14A The fallowing criteria can be cited as reasons for infeasibility without NO ROOFS Bioretention further justification (though some require professional services to or Rain Gardens make the observation): (continued) p Where field testing indicates potential himetention/rain garden sites have measured! (a.ka., initial) native soil saturated hydraulic conductivity less than 0.30 inches per hour. A small scale or largescale PIT in acc9rdance with SWMMWW Volume Ill, Section V 5.4 shall be used to demonstrate infeasibility of bioretention areas. If the measured native sail infiltration rate is less than 0.30 in/hour, bioretentiommin garden BMPs are not required to be evaluated as an option in List d1 or List d2. ❑ Wherethe minimum vertical separation of 3 feet to the seasonal high groundwater elevation, hardpan layer, or other impermeable layer would not be achieved below bioretention that would serve a drainage area that exceeds the following thresholds(and cannot reasonably be broken down into amounts smaller than indicated). • 5,000 square feet of pollution generating immersion surface(PGIS) • 10,000 square feet of impervious area • 0.75 acres of lawn and landscape. ❑ Where the minimum vertical separation of l foot to the sa sonalhigh groundwater or other impermeable layer would not be achieved below bioretention that would serve a drainage area less than the above thresholds. ❑ Within 100feet of a drinking water well, or a spring used for drinking water supply. ❑ Within 10 feet of small on site sewage disposal drainfield, including reserve areas, and grey water reuse systems. For setbacks from a'large onsite sewage disposal system; see Chapter 246272B WAG. City of Everett Public Works Small Project Stormwater Sue Plan Report Dec 2019