Laserfiche WebLink
The subject study area is located in Probable Maximum Thunderstorm Zone II, <br />which has. a one hour rainfall value of 7.0 inches. Probable Maximum <br />General Storm Six Hour Point Value is determined to be 3.3 inches, since <br />the subject area is in Zone B. <br />Surface soil within the drainage area terminating at the Minnesota Dam is <br />typical of the Pinon-Juniper foothills areas of Western Colorado. Surface <br />soil characteristics are shown on Figure 2 and Table 1. <br />• <br />As can be seen from the cited data, the subject area. consists primarily of <br />.soil group The complex number for Antecedent Moisture Condition II has ~ F r <br />been determined to b 68 in accordance with the procedures outlined in the <br />,.r <br />publication, "Design of Small Dams". Details of this computation are <br />illustrated in Table 1. . <br />Concentration time, Tc, has also been determined in accordance with the <br />publication "Design of Small Dams". Since the study area has no <br />approximate uniform gradient, the concentration time was determined in <br />increments. Calculations, which are illustrated in Table 2, yielded a <br />total concentration time of 1.19 Hrs. or 71.4 minutes. <br />Various criteria were considered in order to determine the most critical <br />type of flood for design of the subject structure. Consideration was given <br />to the purpose of the structure, site location, drainage area size, <br />reservoir surface area, storm potential, and snowmelt potential. Due to <br />the geographic location, it was determined that thunderstorm and snowmelt <br />potential provided critical inflow characteristics. <br />VI-10 <br />