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Third Adequacy Review Letter — Environmental Protection Plan - Dated September 6, 2013 <br />Comment ib General Comments — Drawing lacks construction and material specifications for 1.5 foot <br />secondary containment berm. <br />Response: <br />Construction and material specifications have been added to the drawing and the drawing has been <br />modified to reduce dependence on this structure. It was included in the original plan was to show <br />significant overdesign. However, since the secondary volume is not needed to contain the 10 -year <br />event, and the only requirement for it is to provide one inch of additional freeboard above the primary <br />(reference removed) storage surface, the need for elaborate engineering specifications is not necessary. <br />The design calls for a specific type of material, that it be loader placed (compaction not necessary), and <br />that the height and width of the berm be maintained. <br />Comment 3ai General Comments —The 5,100 square foot area appears to have been excluded from <br />the runoff calculation of the diversion channel. <br />Response: <br />The 5,100 square foot disturbed area was included in the calculations. That is the reason the runoff <br />curve shown on the engineering drawing has the two odd - looking highs. The first is from early runoff <br />generated from the disturbed area, and the second is the result of the runoff following surficial <br />saturation of the grass area. The words "grassed and disturbed areas" have been added to the 4 I line <br />below the title "Results of Calculations" to improve clarity. <br />Comment 3aii General Comments —Applicant needs to demonstrate the south run-on diversion is <br />adequate <br />Response: <br />The area has been added to the engineering drawing. For details, see the response to Comment 3c <br />Comment 3b A discrepancy exists between peak flow numbers and SCS curve number (CN) of 42 <br />yields an ratio of initial abstraction number greater than 0.5, therefore suggesting that the SCS <br />method not be appropriate. DRMS estimates the flow to be 1.55 cfs instead of the number of .02 cfs. <br />Response: <br />The reviewer is correct that a discrepancy exists in the drawings with respect to the Q values of 0.02 and <br />1.55 cfs. The 1.55 cfs number was produced from an early calculation and was not changed (corrected) <br />3 <br />