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Table l <br />Peak Runoff Analysis Summary <br />For Access Road <br />Basin <br />No. <br />Basin <br />Area, Sq <br />Ft <br />Length of <br />Flow Path, <br />Feet <br />Average <br />Surface <br />Slope of <br />Basin, % <br />Time of <br />Concentration, <br />Min <br />25 -Year <br />/24 -Hour <br />Runoff Q, <br />CFS <br />50 -Year <br />/24 -Hour <br />Runoff Q, <br />CFS <br />100 -Year <br />/24 -Hour <br />Runoff Q, <br />CFS <br />1 <br />286,673 <br />1600 <br />14.84 <br />19.8 <br />8.4 <br />12.7 <br />17.6 <br />2� <br />502,310 <br />1600 <br />15.63 <br />19.4 <br />14.9 <br />22.6 <br />31.2 <br />3 <br />199,394 <br />1450 <br />12.93 <br />20.0 <br />5.8 <br />8.8 <br />12.2 <br />4 <br />1 75,639 <br />900 <br />17.50 <br />15.0 <br />2.6 <br />3.9 <br />5.4 <br />5 <br />95,244 <br />825 <br />18.10 <br />14.8 <br />3.2 <br />4.8 <br />6.7 <br />6 <br />29,206 <br />275 <br />18.16 <br />11.5 <br />1.1 <br />1.7 <br />2.4 <br />7 <br />10,736 <br />300 <br />20.83 <br />11.7 <br />0.4 <br />0.6 <br />0.9 <br />8 <br />41,415 <br />475 <br />18.42 <br />12.6 <br />1.5 <br />2.3 <br />3.2 <br />9 <br />68,863 <br />400 <br />20.63 <br />12.2 <br />2.6 <br />3.9 <br />5.5 <br />10 <br />156,592 <br />600 <br />15.63 <br />13.3 <br />5.7 <br />8.6 <br />11.9 <br />11 <br />69,474 <br />350 <br />25.00 <br />11.9 <br />2.7 <br />4.0 <br />5.6 <br />12 <br />17,034 <br />275 <br />18.18 <br />12.1 <br />0.6 <br />1.0 <br />1.4 <br />13 <br />30,526 <br />320 <br />11.72 <br />11.8 <br />1.2 <br />l.8 <br />2.5 <br />» Drainage Basins l and 2 are shown in this Table; however, the runoff from these areas do not cross or <br />impact the access road. Runoff from these areas is managed with retention ponds on the Operations Site. <br />(NOTE: Although the basins are not urbanized; however, as a "check ", and for the purposes of <br />establishing a minimum Time of Concentration, the equation from the Manual of t,= L/I 80+10 was used. <br />If the calculated Time of Concentration for Overland and Channelized flow was less than the "check ", the <br />check value was used.) <br />The calculations for determining the culvert sizes to convey drainage water under the roadway were <br />completed using the software package Culvert Master. All culvert structures were sized based on the 100 - <br />year peak runoff rate presented in Table 1 above. Culvert material, for sizing purposes, is assumed to be <br />corrugated metal pipe (CMP) and smooth interior HDPE culvert material. Headwater depth for sizing the <br />culvert for the design Q was restricted to not more than the depth or diameter of the culvert. Maximum <br />capacity of the culvert was based on allowing the headwater to be at a one foot depth above the culvert's <br />inlet top of pipe. This assumes that the culvert would have a minimum cover depth over the pipe of one <br />foot, allowing the water to submerge the inlet without over topping the road. Lengths for the culverts <br />were assumed to be 50 -feet, final culvert length will be determined from the topographic data collected by <br />SMA. Velocities greater than 2 fps were targeted to be maintained to ensure that the culvert would be <br />self - cleaning. Minimum culvert size considered was 18 -inch diameter, Presented below in Table 2- <br />Culvert Requirements Resulting from 100- year /24 -Hr Rainfall Event for Access Road, are the culvert <br />sizes required to convey water under the roadway at the locations identified on the plans. The detailed <br />analytical parameters and the results of the calculations are presented in Appendix 2 - Culvert Analysis. <br />17 <br />