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(x) Must provide at least one soil boring test pit or infiltrometer test in the <br /> location of the infiltration practice for determining infiltration rates; <br /> (xi) For design purposes, divide field measured infiltration rates by 2 as a safety <br /> factor or use soil-boring results with the infiltration rate chart in the Minnesota <br /> Stormwater Manual to determine design infiltration rates. When soil borings <br /> indicate type A soils, field measurements should be performed to verify the <br /> rate is not above 8.3 inches per hour. <br /> (xii) Must employ appropriate on-site testing to ensure a minimum of three(3) feet <br /> of spparation from the seasonally saturated soils(or from bedrock) and the <br /> bottom of the proposed infiltration system; <br /> (xiii) Must design a maintenance access, typically eight (8) feet wide; <br /> (xiv) Infiltration Systems are prohibited in the following areas (See "higher level of <br /> engineering review" in the Minnesota Stormwater Manual for more <br /> information): <br /> i. Areas that that receive runoff from vehicle fueling and maintenance <br /> areas; <br /> ii. Areas where infiltrating stormwater may mobilize high levels of <br /> contaminants in soil or groundwater; <br /> iii. Areas where soil infiltration rates are field measured at more than 8.3 <br /> inches per hour unless the soils are amended to slow the infiltration <br /> rate below 8.3 inches per hour; <br /> iv. Areas with less than three(3) feet of separation distance from the <br /> bottom of the infiltration system to the elevation of the seasonally <br /> saturated soils or the top of bedrock; <br /> v. Areas of predominately Hydrologic Soil Group type D soils(clay); <br /> vi. The following areas within a Drinking Water Suppler eg ment <br /> Area(DWSMA) as defined in Minn. R. 4720.5100, subp. 13: <br /> 1. In an Emergency Response Area(ERA) within a DWSMA <br /> classified as having high or very high vulnerability as defined <br /> by the Minnesota Department of Health; or <br /> 2. In an ERA within a DWSMA classified as moderate <br /> vulnerability unless a higher level of engineering review <br /> sufficient to provide a functioning treatment system and to <br /> prevent adverse impacts to groundwater has been approved by <br /> the City of Arden Hills; or <br /> 3. Outside of an ERA within a DWSMA classified as having high <br /> or very_high vulnerability unless a higher level of en ineering <br /> review sufficient to provide a functioning treatment system and <br /> to prevent adverse impacts to groundwater has been approved <br /> by the City of Arden Hills. <br /> Page 4 of 7 <br />