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Technical Revision 90-06 <br />• ~ Categories for disturbed, reclaimed, and undisturbed sub-areas within the <br />contributing drainage area were identified <br />~ The acreage of individual sub-areas was determined by planimeter using a 1" <br />= 200 topographic map <br />~ For each sub-area category the "Hydrologic Soil Cover Complex" index number <br />(CN) was determined for standard antecedent moisture conditions (AMC-I1) <br />~ Runoff for each sub-area was determine Busing runoff tables from the SCS <br />"National Engineering Handbook, Section 4 -Hydrology" <br />~ A weighted average runoff for each design storm event was calculated for the <br />• <br />contributing drainage area <br />~ The "Hydrologic Soil Cover Complex" index number for the contributing <br />drainage area was determined bycross-referencing the corresponding weighted <br />average runoff figure back to the runoff tables <br />~ The total runoff volume for the design strom event was calculated by <br />multiplying the weighted average runoff value by the total contributing drainage <br />area <br />Peak Discharge <br />The peak discharge resulting from the respective design storm events was determined by <br />utilizing the standard SCS method outlined in Technical release No. 55: <br />• The total contributing drainage area was determined by adding the sub-areas <br />utilized in the runoff calculations and was checked by planimetering the <br />• drainage area boundary on a 1" = 200' topography map <br />TR 90-06 Exhibit 3 - 6 Revised 11 /16/90 <br />