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i. To the maximum extent practicable, volume control shall be fully met onsite <br />(Section 2, Subsection 2b). Site conditions may make infiltration undesirable or <br />impossible. The applicant must make soil corrections and/or investigate other <br />locations on the site for feasible infiltration locations. Infiltration practices are not <br />allowed: <br />1. For runoff from fueling and vehicle maintenance areas; <br />2. Within hydrologic soil group D type soils; <br />3. Within some Wellhead Protection Areas (Review Wellhead Protection <br />Plans for additional guidance); <br />4. Within 50 feet of a septic tank or drain field; <br />5. On areas with less than three (3) feet vertical separation from the <br />bottom of the infiltration system to the elevation of seasonal high <br />groundwater or top of bedrock. <br />If the applicant claims that infiltration is not feasible or allowed onsite, the <br />applicant must provide supporting documentation and follow Section 2, <br />Subsection 4. <br />22.2.4 Alternative Compliance Sequencing. For sites where infiltration practices are <br />determined infeasible as described in Section 22.2.3(i), the following Alternative <br />Compliance Sequencing steps shall be taken in the order shown: <br />a. Use of alternative volume control practices as described in the Minnesota <br />Stormwater Manual, 2005, and as amended, sized according to Section 22.2.2(b). <br />b. Use of on -site filtration practices and biofiltration using an impermeable liner <br />and under drain, sized to filter a volume of runoff according to Section 22.2.2(b). <br />c. Use of off -site volume control practices sized according to Section 22.2.2(b). <br />Off -site volume control practices can be used to provide for stormwater <br />management based on the following criteria: <br />1. Off -site practices shall be constructed within the same drainage area or <br />subwatershed as the project site. <br />2. Off -site practices are required to be constructed and operational prior to <br />constructing imperviousness within the contributing drainage area. <br />d. Use of wet sediment basins sized per the standard described within the MPCA <br />General Permit for Construction Activities, 2008, and as amended. <br />22.2.5 Volume Control Credits. <br />a. Volume control credits will be awarded as described in the Minnesota <br />Stormwater Manual, 2005, and as amended. <br />b. Volume control credits must be determined based on the methods outlined <br />within Chapter 11 of the Minnesota Stormwater Manual, 2005, and as amended, <br />for the Adjusted Water Quality Volume. <br />