CT2015-024 Increase Approval Letter

Home Browse Search

North Poudre Irrigation Company Agenda Item 24b September 15-17,2015 Board Meeting(Updated September 18, 2015) Page 2 of 4 Background The North Poudre Irrigation Company serves approximately 28,000 irrigated acres in Larimer County north of Fort Collins near Wellington. The Company owns Fossil Creek Reservoir located in South Fort Collins. There are 5,656 acre-feet of water diverted through the Fossil Creek Reservoir Inlet headgates annually. This water is used by shareholders of 149 preferred water rights to irrigate approximately 2,200 acres of farmland. During the unprecedented flood of September 2013 in the tributaries to the South Platte River, a significant number of diversion structures and dams along the river corridor were damaged, including the Company's river diversion for Fossil Creek Reservoir. The Fossil Creek Reservoir Diversion Structure consists of a concrete structure that spans the Cache la Poudre River and contains a 10-foot wide radial gate at the right abutment. The diversion structure checks the river approximately two feet in elevation to permit delivery to the Fossil Creek Reservoir Canal. The diversion structure ties into the right abutment headgate structure with two eight foot-wide by three-foot high radial gates that control discharge into the Fossil Creek Reservoir Canal which flows to Fossil Creek Reservoir approximately 5 miles downstream. Prior to the 2013 flood, the diversion structure was fully functional and in place. Since point elevations of the structure were surveyed for an unrelated floodplain study in 2013, pre-flood conditions are recorded. During the 2013 flood, the river scoured material beneath the structure leaving a void underneath. The diversion structure broke near the center of the river and collapsed into the void. The diversion structure was not attached to the left abutment structure and was only attached to the right abutment structure by way of the radial gate. The concrete broke in the center so that when the center collapsed into the void, the two abutment ends became elevated. Elevation of the left abutment end of the diversion, combined with scouring and rapid drawdown of water, damaged the left abutment structure. Elevation of the right abutment end of the diversion damaged the radial gate, but there appears to be no damage to the right abutment headgate structure. Water Rights The water rights impacted by this project include TABLE 1: IMPACTED WATER RIGHTS Name Amount (AF) Appropriation Date Adjudication Date Fossil Creek Reservoir 808 3/1/1862 4/11/1882 Fossil Creek Reservoir 808 9/15/1864 4/11/1882 Fossil Creek Reservoir 808 3/15/1868 4/11/1882 Fossil Creek Reservoir 808 3/20/1873 4/11/1882 Fossil Creek Reservoir 808 4/1/1878 4/11/1882 Fossil Creek Reservoir 808 4/25/1881 4/11/1882 Fossil Creek Reservoir 808 9/28/1914 12/18/1945 Average annual diversions of the Company are 44,400 AF. Average annual diversions through the Fossil Creek Reservoir Inlet Diversion Structure are 5,656 AF. Project Update FEMA visited the site on December 17, 2013 to determine the extent of the damages and prepare the Project Worksheet. The worksheet estimated the damage at $659,897 which included $111,880 of mitigation to improve the stability of the structure, $546,600 of repair costs, and $1,417 of direct administration costs. This cost estimate assumed that construction would occur once the river receded to historic pre-flood levels, enabling the river to be diverted through the Fossil Creek Inlet Ditch while repairs were made to the structure. This meant construction prior to the 2014 irrigation season would not be possible. The Project was bid in the fall of 2014 with a stipulation that flows in the river be below 100 cfs for 10 consecutive days prior to December 1. The river level remained near 200 cfs and thus the bidding process was cancelled. In response to the high river flows, the Project was redesigned to allow flows to be bypassed through the construction zone, which requires the Project to be built in two stages which will increase construction cost. The Project was put out to bid in July 2015 and four bids were received