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<br /> <br />9. The estimated storage volume for the surface facility detention pond is: <br /> Volume, cu. ft. <br /> 10 yr - 24 hr 25 yr - 24 hr 100 yr - 24 hr <br />Storage 5,587 7.988 11,361 <br />Runoff 15,383 2.1.800 35,340 <br />' The estimated dimensions across the top of [he detention pond aze 1 l0 feet by 110 <br />feet. The pond has been sized using a 3:1 slope. <br />' 10. The calculated capacity for the discharge using the historic 25 yr. runoff is a 12" <br />PVC pipe that is fitted with an orifice. The emergency spillway has been sized to <br />handle the 100 yr. event and has the following dimensions: <br />1 <br /> <br /> <br />1 <br /> <br />1 <br /> <br /> <br />1 <br /> <br /> <br />Description Feet <br />Bottom of Ditch 2.50 <br />Depth of Flow I.00 <br />Ditch Width -Top of Flow 7.50 <br />Ditch Width -Top of Ditch 9.00 <br />Freeboazd 0.30 <br />Ditch Side Slope 2.x:1 <br />Velocity, fps 3.14 <br />[t is recommended that the emergency spillway be lined with a riprap having a Dso <br />of 6 inches. A geotextile fabric should be placed between the soil and riprap for <br />all applications. <br />11. [t is recommended that a diversion ditch be constructed in the CDOT right-of way <br />to divert the storm water runoff from the I-70 corridor azound the Dry Creek <br />surface facility area. The diversion ditch contains a flatter section from the <br />culvert inlet to the top of the slough bank and the slough bank. The diversion <br />ditch cross sectional area for the flatter section of the ditch is: <br />Description Feet <br />Bottom of Ditch 3.00 <br />Depth of Flow 1.90 <br />Ditch Width - Top of Flow 14.40 <br />Ditch Width -Top of Ditch 16.20 <br />Freeboazd 0.30 <br />Ditch Side Slope 3:1 <br />Velocity, fps 2.46 <br /> <br />