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Page 12 of 26 <br />Permit No: 1MN R100001 <br />g. Adequate maintenance access must be provided (typically 8 .Ft. ,vide) along with a <br />maintenance plan identifying whom will be performing fixture maintenance of the infiltration <br />or filtration system. <br />h. Use of designed infiltration systems from industrial areas with exposed significant materials <br />or from vehicle fueling and maintenance areas is prohibited. <br />3. Regional Ponds <br />Regional ponds can be used provided that they are constructed ponds, not a natural wetland or <br />waterbody, (wetlands used as regional ponds must be mitigated for, see Appendix A) and <br />designed in accordance with this permit's design requirements (see Part III.C. l) for all water from <br />impervious surfaces that reach the pond. Permittees shall not construct regional ponds in <br />wetlands, regardless of their condition, quality or designation by local plans, unless the <br />mitigative sequence in Appendix A. D.2 of this permit has been completed. There must be no <br />significant degradation of the waterways between the project and the regional pond. The owner <br />must obtain written authorization from the applicable local governmental unit (LGU) or private <br />entity that owns and maintains the regional pond. The LGU's or private entity's written <br />authorization must identify that the regional pond will discharge the water quality volume ('/2 <br />inch of runoff from the impervious watershed area) at no more than 5.66 cfs per acre of surface <br />area of the pond. The owner must include the LGU's or private entity's written authorization in <br />the SWPPP. The LGU's or private entity's written authorization must be obtained before the <br />owner finalizes the SWPPP and before any application for this permit is made to the MPGA. <br />4. Combination of Practices <br />A combination of practices, including those required by a LGU, which meet the requirements of <br />Part III.C.1, 2 and 3 respectively, (i.e., wet sedimentation basins, infiltration/filtration, and <br />regional ponds) may be used such that the water quality volume of '/2 inch of runoff from the <br />new impervious surfaces created by the project is accounted for in the owner's permanent <br />storm water management system (e.g., '/4 inch infiltrated and '/4 inch treated through a wet <br />sedimentation basin). If any combination of these practices is used, the SWPPP must contain <br />documentation (e.g., LGU or private entity's authorization, infiltration computer model results or <br />calculations, etc.) identifying the volume that each practice addresses. <br />5. Alternative Method <br />Where an alternative, innovative treatment system is proposed and demonstrated by calculation, <br />design or other independent methods to achieve approximately 80% removal of total suspended <br />solids on an annual average basis, the Commissioner will approve the method if the process <br />outlined in Part II.B.3.c. is completed, and the following information is submitted: <br />a. All calculations, drainage areas, plans, and specifications for the proposed alternative method <br />and a graphic representation of the area to be served by the method. These items must be <br />included in the SWPPP and submitted to the MPCA at least 90 days prior to the proposed <br />starting date of the construction activity. <br />b. A 2 year monitoring plan to sample runoff from the proposed method. The plan must include <br />a discussion of the methods used to collect samples, location where samples will be taken <br />(upstream and downstream of the proposed method), frequency of samples (minimum of six <br />wq-smn2-51 <br />