FLOOD06965 - Laserfiche WebLink

Home Browse Search

.' I I I II I I I I, I I I I I) I I I I I 7. Drawing GH-7 (Sheet 9 of 30), Grange Hall Creek Sta. 130+00 to 100+00 The main channel in this reach is narrow and incised with a relatively steep, longitudinal slope. The majority of the storm flows are carried in the main channel with high flow velocities. Overbank flooding also occurs which increases the flood plain width. The channel is crossed by the Colorado Agricultural Canal (pipe). The potential flood damages in the reach consist of erosion and clean-up, vegetal growth wash-out, and potential loss of livestock. The improvements consists of the construction of four concrete check drop structures along the main channel to control erosion. 8. Drawing GH-8 (Sheet 10 of 30), Grange Hall Creek Sta. 100+00 to 70+00 The main channel in this reach is narrow and incised with a steep longitudinal slope from Station 100+00 to Riverdale Road. Below Riverdale Road the channel has been altered by numerous years of farming with the resulting Grange Hall Creek flood plain being very broad and shallow. A low flow or pilot channel below Riverdale Road is in evidence through this reach, although it appears to be used as an irrigation drainage ditch. The potential flood damages consist of erosion, loss of crops and livestock, damage to farm equipment, and limited residential inundation. The improvements in this reach consist of the following: (I) Two concrete check drop structures above Riverdale Road. (2) Construction of a triple wide 4' x 8' RCBC culvert (60') and the 40' extension of the existing bridge at the Riverdale Road crossing (20' each side of Riverdale Road). (3) Construction of a 30' extension on the north end of the existing Lower Clear Creek Canal siphon at approximately Station 79+30. (4) A channelization of the area of the Grange Hall Creek from Riverdale Road to Station 70+00. The channel is designed to keep the 100-year flood within a 2('0' right-of-way below Riverdale Road. The channelization improvements below Riverdale Road are to be the responsibility of the private property owners in the area, if the property owners determine that the improvements are economically justified when considering potential flood damage costs. The confluence of the Undefined Tributary with Grange Hall Creek occurs just above Riverdale Road. The investigation of the flood hazards and drainage improvements for the tributary were not part of this study. 9. Drawings GH-9 (Sheet II of 30), GH-I 0 (Sheet 12 of 30), and GH-II (Sheet Q of 30), Grange Hall Creek Station 70+00 to 0+00 The channel in this reach has been altered by numerous years of farming with the resulting Grange Hall Creek flood plain being very broad and shallow. A low flow or pilot channel is in evidence through this reach, although it appears to be used as an irrigation or drainage ditch. The potential flood damages consist of erosion, loss of crops, loss of livestock, damage to farm equipment, limited residential inundation, and interrupted operation of the sand and gravel plant along the banks of the South Platte River. A portion of this reach is also subject to flooding from the South Platte River and lies within the currently defined South Platte River flood plain. The improvements in the area included on the GH-9, GH-IO, and GH-II drawings consist of channelization for the area of Grange Hall Creek from Station 70+00 to 4+00. The channel is designed to keep the 100-year flood within a 200' right-of-way in this area. The channelization improvements below Riverdale Road are to be the responsibility of the private property owners in this area if the property owners determine that the improvements are economically justified when considering potential flood damage costs. No public monies are to be allocated to the improvements below Riverdale Road. 16