Laserfiche WebLink
SEDAI.WK1 <br />LILLYLANDS INC. <br /> PROTECTION OF THE HYDROLOGIC BALANCE <br /> STORM EVENTS <br /> 10 YEAR 24 HOUR EVENT 1.6 INCHES <br /> 25 YEAR 24 HOUR EVENT 2.0 INCHES <br /> 100 YEAR 24 HOUR EVENT 2.4 INCHES <br />The run-off calculations presented below are calculated based <br />on the manual - Procedures for Determining Peak Flows in <br />Colorado - published by the Soil Conservation Service March <br />1984. <br />Curve numbers were developed using soil caracteristics and <br />run-off control techniques. The soil types that are present <br />on the site are caracterized as having moderate permeability. <br />According to the definition of the hydrologic soil groups, <br />the soils on the site fall into the B hydrologic soil group. <br />According to availabe vegetation studies the existing <br />vegetation cover ranges from 20% to 24%. From Figure S-3 on <br />page 23 of the referenced handbook the curve number for the <br />existing undisturbed vegetation is 64. <br />• The areas where the soil is void of vegetation because of <br />topsoil has been redistributed is characterized as poor pasture <br />or range. It should be noted that these areas will be seeded <br />mulched at least once per year. From Figure S-4 on page 24 <br />of the referenced handbook the curve number for poor range <br />is 79. A curve number of 80 caill be used. <br />SEDIMENT POND A CAPACITY <br />Sediment pond A is to be constructed north of the disturbed <br />areas. It will contain the run-off from the central portion <br />of Mining Area No. 1 and the topsoil stockpile. <br />RUN-OFF VOLUME - - POND A <br />PRECIP DIRECT RUN-OFF <br />ACRES CURVE AMOUNT RUN-OFF VOLUME AF <br />78.8 80 1.6 0.34 2.21 <br />• TOTAL REQUIRED WATER VOLUME 2.21 <br />9-1 <br />