FLOOD10480 - Laserfiche WebLink

Home Browse Search

I I I I I I I I I I I I I I I I I I I In addition, containment of water during construction would be needed for the construction of toe protection at scour depth. Historical records of minimum flows along the Arkansas River at Cafton City show a typical low flow depth of about 3 feet across the entire channel width. The estimates include removal of the existing levee prior to the construction of the soil cement levee, WRC assumed that suitable sandy soil is available nearby for use in the preparation of coil cement (excavated channel bank soil may be suitable). If suitable soil is not available, RCC could be used. Soil cement is laid out in lifts which are poured in-place and compacted. Typical lift heights are 0.5 feet but can vary. The top width of the highest lift should not be less than 8 feet. WRC found that 1 (horizontal) to 1 (vertical) side slopes would fit the base lift between the channel bank and Riverview Drive for the 11,350 cfs flood event. The larger magnitude floods would require slightly steeper slopes in some areas where the distance between the channel bank and the road is more constricted. WRC evaluated the estimated cost of riprap lined channel/soil cement levee option for three separate flood events of increasing magnitude. Exhibit C shows the extent of improvements required along the south channel bank for flows of 11,350, 12,265, and 13,220 cfs. The 11,350 cfs event corresponds to the magnitude of the flood event that the southern bank could sustain before the weir was constructed assuming the existing levee did not fail. The two larger flows correspond to water levels 0.5 and 1.0 feet higher than the 11,350 cfs flood. Table 3 shows the approximate return periods and estimated costs of improvements for the base case and the three evaluated flows. Flow (cfs) Return Period (yrs) 9 18 ------2r--- 25 100 Levee Height Estimated Cost ($) at Section 2.0 7000 (base case) N/A $ 0 4.4 $ 400,000 - 4.9--- - -$"- -499~00(j ------ - 5.4 $ 608,000 ~.__._._----_.. ---...--..- -~ -- 11350 _____u -- '-12265-- -, 13220 20,500 * 7.4 * levee height does not include 3-feet of freeboard 6