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• ROAD.WK1 <br />LILLYLANDS INC. <br />PROTECTION OF THE HYDROLOGIC BALANCE <br />ACCESS & HAUL ROAD CULVERTS AND BORROW DITCHES <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 will be used. <br />The following calculations are for the culverts to be <br />under the access roads. Only 18" and 24 culverts will <br />be utilized even though the calculations indicate that <br />in many areas a 12" diameter CMP will suffice. This is <br />done becuuse of the difficulty of keeping a 12" CMP from <br />silting up. <br />The location of the haul and access roads is shown on Drawing <br />Number 114. Detaials of the roads are presented on Drawing <br />Noa. 121, 122, 123 & 124. <br />Following is a table that lists the culvert numbers and <br />the road station where each culvert is located. <br />CMP# ROAD CMP# ROAD CMP# ROAD <br /> STATION STATION STATION <br />1 00+70 5 84+70 9 120+40 <br />2 38+65 6 100+20 10 126+35 <br />• 3 78+15 7 104+30 11 141+30 <br />4 82+80 8 113+90 12 146+30 <br />9-24 July 1991 <br />