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model will replace the currently approved Prospect Pond model for the 10 year, 24-hour <br />storm event. <br />The Division will not approved hydrologic soil cover complex (CN) values of 56 for 3 <br />year and older reclamation within the Prospect watershed. In the Division's opinion <br />and in the absence of significant, site-specific supporting evidence or documentation, <br />a curve number this low does not accurately represent the hydrologic soil cover <br />conditions for these more mature reclaimed areas. The Division is aware of a pending <br />technical revision (TR-73), yet to be approved, that proposed changes to curve <br />number values from specific values to a range of values. Please review this pending <br />revision for proposed curve number ranges and considering revising the Prospect <br />Pond 10 year, 24-hour model. <br />2. Please submit SEDCAD modeling that demonstrates that the Prospect Pond spillway <br />system will safely pass the 25 year, 24-hour storm event. Unless ditches A, B, and C <br />are designed to divert the 25 year, 24 hour storm event, 25 year storm runoff will also <br />need to be included in the Prospect Pond spillway design run. <br />3. Based on soils information from the approved permit, the majority of the soils in the <br />Prospect watershed are comprised of one of the following soils shown in the table <br />below. Selection of CN values should reflect these fine textured soils having a slow <br />infiltration rate. With the potential for compaction upon reapplication of soils, <br />considering all soils as category C is preferred. <br />Soil name Hydrologic Soil Group <br />Burnett loam [C <br />Campsass -B <br />Work loam 1C <br />If you have any questions, please let me know.