2016-04-26_PWETC_AgendaPacket - Laserfiche WebLink

Home

Page 16 of 38 Permit No: MNR040000 a) Where industrial facilities are not authorized to infiltrate industrial stormwater under an NPDES/SDS Industrial Stormwater Permit issued by the Agency b) Where vehicle fueling and maintenance occur c) With less than three (3)feet of separation distance from the bottom of the infiltration system to the elevation of the seasonally saturated soils or the top of bedrock d) Where high levels of contaminants in soil or groundwater will be mobilized by the infiltrating stormwater 2) The permittee's Regulatory Mechanism(s) shall restrict the use of infiltration techniques to achieve the conditions for post-construction stormwater management,without higher engineering review, sufficient to provide a functioning treatment system and prevent adverse impacts to groundwater, when the infiltration device will be constructed in areas: a) With predominately Hydrologic Soil Group D (clay) soils b) Within 1,000 feet up-gradient, or 100 feet down-gradient of active karst features c) Within a Drinking Water Supply Management Area (DWSMA) as defined in Minn. R. 4720.5100, subp. 13 d) Where soil infiltration rates are more than 8.3 inches per hour 3) For linear projects where the lack of right-of-way precludes the installation of volume control practices that meet the conditions for post-construction stormwater management in Part.III.D.5.a(2), the permittee's Regulatory Mechanism(s) may allow exceptions as described in Part III.D.5.a(3)(b).The permittee's Regulatory Mechanism(s) shall ensure that a reasonable attempt be made to obtain right-of-way during the project planning process. (b) Exceptions for stormwater discharge volume The permittee's Regulatory Mechanism(s) may allow for lesser volume control on the site of the original construction activity than that in Part III.D.5.a(2) only under the following circumstances: 1) The owner and/or operator of a construction activity is precluded from infiltrating stormwater through a designed system due to any of the infiltration related limitations described above, and 2) The owner and/or operator of the construction activity implements, to the MEP, volume reduction techniques, other than infiltration, (e.g., evapotranspiration, reuse/harvesting, conservation design,green roofs, etc.) on the site of the original construction activity that reduces stormwater discharge volume, but may not meet the conditions for post- construction stormwater management in Part III.D.5.a(2).