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(3) For alternative Stormwater BMPs not found in Table C1 or to deviate from TP <br />Removal Factors found in Table C1, the applicant may submit a TP Removal <br />Factor, expressed as annual percentage removal efficiency, based on supporting <br />technical data, for District approval. <br />(4) Stormwater runoff treated by the BMP during a rain event will not be credited <br />towards the treatment requirement. <br />TABLE C1. TP REMOVAL FACTORS FOR PROPERLY DESIGNED BMPS. <br />BMP <br />BMP Design Variation <br />TP Removals Factor <br />Infiltration ** <br />Infiltration Feature <br />1.00 <br />Water Reuse ** <br />Irrigation <br />1.00 <br />Biofiltration <br />Underdrain <br />0.65 <br />Filtration <br />Sand or Rock Filter <br />0.50 <br />Stormwater Wetlands <br />Shallow Wetland <br />Pond/Wetland <br />0.40 <br />0.55 <br />Stormwater Ponds *** <br />Wet Pond <br />Multiple Pond <br />0.50 <br />0.60 <br />Source: Adapted from Table 7.4 from the Minnesota Stormwater Manual, MPGA. <br />* Refer to MPCA Stormwater Manual for additional information on BMP performance. <br />Removal factors shown are average annual TP percentage removal efficiencies intended <br />solely for use in comparing the performance equivalence of various BMPs. <br />** These BMPs reduce runoff volume. <br />*** Stormwater ponds must also provide 2.5" of dead storage as required by Section 9(d)(2). <br />(d) BMP LOCATIONAL SITING. <br />(1) BMPs shall be located either on-site to treat runoff at the point of generation, or <br />regionally within the Resource of Concern Drainage Area. <br />(2) If infiltration is feasible on site (see Table C2), on-site or regional BMPs must <br />provide volume control to meet the standard of subsection 6(c). If infiltration is not <br />feasible, any BMP may be used. <br />(3) Off-site and/or regional BMPs must be sited in the following priority order: <br />(i) In a downstream location that intercepts the runoff volume leaving the <br />project site prior to the Resource of Concern. <br />(H) Anywhere within the same Resource of Concern Drainage Area (see Figures <br />CIA -CIE) that results in no greater mass of Total Phosphorus reaching <br />the resource of concern than on-site BMPs. <br />17 <br />