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<br />then calculated. The percentage of pervIous and impervious areas <br /> <br /> <br />was determined for each area for present and proposed land use hy <br /> <br /> <br />uLllizing the information presented c,Hlier on the prescnt land use <br /> <br /> <br />map, Plate 1, Volume 2 and proposed L,nd use map, Plate 2, Volume 2. <br /> <br /> <br />T<lble 2..1 in the runoff section of tlw Criteria Manual was used as a <br /> <br /> <br />guide for l<Jnd use versus percent of perviOUS-Impervious, Depression <br /> <br /> <br />,lnd detention losses were determined [rom Table 2..2. An infiltration <br /> <br /> <br />r;de of one-half inch per hour was used as recollllilended by the Cri teri eJ <br /> <br /> <br />~l;lJlu;:l. Actual field infiltration te~;ts \Vere not conducted, since <br /> <br /> <br />detailed information on soils churo.cteristic; (See Section Ii), slope <br /> <br /> <br />o[ land, ground cover, etc. were rCc1dLly a,.ailable to make the inril- <br /> <br /> <br />tration rate determination. <br /> <br /> <br />The following Table 111-1 and calculations are presented us an <br /> <br /> <br />eXClmple for Area I (lOa-year frequency storm) of the Big Dry Creek <br /> <br /> <br />Basin for determining the effective precipitation, defined as th;lt <br /> <br /> <br />portion of rainfall that becomes runoff. The sample G]]culatiolls <Ire <br /> <br />based on proposed land use. <br /> <br />- 2i ,., <br />