Laserfiche WebLink
<br />II1-IO <br /> <br />D & RGW Railroad and Tennyson Street overtops Tennyson Street and flows east <br />either along the railroad tracks or into the Crestview water supply pond. <br />Based upon the amount of overflow volume, the overflow would be retained <br />by the Crestview ponds and therefore would not combine with the flows along <br />Lowell Boulevard. <br />In the Bates Lake Planning Basin, two flow splitting conditions were <br />identified, one at 60th and Depew Street and one at Sheridan Boulevard and the <br />D & RGW Railroad. The splitting of flows at these locations is due to the <br />capacity of the existing storm sewers at the locations which carry some of the <br />storm water a different direction than the direction the ground contours carry <br />the flow on the surface. The degree of flow splitting was estimated by comparing <br />the maximum capacity of the storm sewer to the appropriate storm hydrograph. <br />A hydrograph of the storm sewer flow was then estimated, assuming a similar <br />shape of the rise and falling leg of the total hydrograph. The overflow <br />hydrograph is then the subtraction of the storm sewer hydrograph from the total <br />hydrograph. <br />5. Comparison With Flood Records <br />The stage discharge and rainfall gauge at 69th and Sheridan Boulevard <br />(U.S.G.S. #06/7197.70) recorded the runoff from the storm of May 5 and 6, 1973 <br />as well as the five-minute incremental rainfall values. The resulting hydrograph <br />from the storm is presented in Figure 111-9 and includes the hyetograph for one- <br />hour increments. The maximum 24-hour total precipitation was 2.61 inches, <br />which resulted in 140 acre-feet of runoff. Based on a tributary area of 933 <br />acres, as defined in this study, the excess precipitation was 1.8 inches or <br />69% of the total precipitation. The maximum five-minute incremental precipi- <br />tation value was 0.04 inches, which resulted in a peak runoff rate of 193 cfs. <br />