CT2015-027 Increase 2 Approval Letter

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Pisgah Reservoir and Ditch Company Agenda Item 12a July 15-16, 2015 Board Meeting(Updated July 17,2015) Page 2 of 4 Background The Company owns and operates Wrights Reservoir and Pisgah Dam (Pisgah), located in Teller County, for the benefit of its shareholders. The reservoir is an on-channel reservoir along Fourmile Creek and has a normal storage capacity of 2,192 acre-feet (AF). After release from the reservoir, Fourmile Creek conveys the Company's water to the Arkansas River, where it passes through Pueblo Reservoir before being diverted to shareholders through the Catlin Canal. Pisgah was originally constructed in 1911. It is classified as a significant hazard dam and stands 69 feet high, 610 feet long, and 12 feet wide at the crest. As the result of an upstream slope failure in 1928, a new outlet conduit was constructed through the right abutment, and the original outlet works were abandoned. In 1988, the spillway was enlarged to pass the 100-yr, 24-hr rain event in accordance with the State Engineer's Office (SEO) guidelines. An additional spillway study began in 2010 using the SEO's Extreme Precipitation Analysis Tool (EPAT) but is on hold in the expectation that the SEO will resolve the errors and inconsistencies which have been found in EPAT. The SEO inspected Pisgah in June 2011. The Engineer's Inspection Report issued by the SEO identified multiple deficiencies and safety concerns and placed conditional requirements on the full storage capacity of the reservoir. To avoid a storage level restriction order, the Company is required to modify the outlet works and replace the existing control valves. Project Update The Project is intended to improve the safety and operation of the dam's low level outlet works through the right abutment and properly abandon the dam's original outlet conduits. Final design and construction plans were completed and approved by the SEO in October 2014. Project changes between the preliminary and final design included: replacing both gate valves instead of eliminating one and only replacing one; using the new upstream sluice gate as solely a guard gate and using new mid-dam knife gate valves for flow control; and properly abandoning the old outlet works. With the exception of the proper abandonment of the old outlet works which was identified as a need during a 2013 SEO inspection of the old outlet, these elements were identified as alternatives in the original 2012 Feasibility Study. Because of the specialized underwater construction work, bids were solicited from pre-qualified contractors. The Company's design engineer, RJH Consultants, Inc., reviewed the three bids received, and the low-bidder, Inland Potable Services (Contractor), was awarded the contract. The Contractor has divided the work into three separate phases which includes the following: Phase I-Abandoned Outlet Works: Proper abandonment of the dual non-functioning 16-inch diameter outlet conduits originally abandoned in 1928. Includes grouting the conduits and installing a filter diaphragm and drainage system at the discharge end of the conduits. Phase II- Sluice Gate: Installation of an upstream gate to allow for an unpressurized outlet. Includes installation of a sluice gate on the intake structure, hydraulic cylinder, hydraulic control and vent piping, and removal and replacement of the trash rack. Phase III- Gate Valves: Replacement of the outlet control valves. Includes the removal of existing gate valve operators and valve stems, installation of discharge pipe liners, installation of new knife gate valves, installation of hydraulic controls and piping, replacement of the access ladder, replacement of the valve operator building, and concrete tunnel repairs. The updated Project cost, updated by the Contractor's bid amount, is shown in Table 1.