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Church Ditch Water Authority October 18, 2013 (Updated October 21, 2013) Page 3 of 4 Project Description Agenda Item 8j The goal of this project is to reestablish the operational function of the Church Ditch as a water supply structure and to ensure the continuation of future deliveries. Ecological Resource Consultants, Inc. has been retained to design a suitable repair for the Leyden Creek Crossing and to provide engineering services for the other locations as needed. Alternative 1 — Do Nothing: This alternative is considered unacceptable. With the inability to cross Leyden Creek and safely convey water in areas of the other areas of damage, Church Ditch would be unable to deliver to its contractual users and would eliminate a critical raw water supply source for the cities of Arvada, Northglenn, Westminster, and Broomfield. Alternative 2 — Rebuilding Collaboratively with Improvements: The Leyden Crossing is located in unincorporated Jefferson County in planned open space away from other development or infrastructure. The other smaller areas of damage are limited to the Church Ditch itself. Collaboration with other agencies is not feasible. Selected Alternative 3 — Church Ditch Flood Repairs: This alternative entails restoring the Church Ditch to pre -flood conditions. The Leyden Creek Crossing Structure will be rebuilt with this section of the ditch piped to prevent the uncontrolled diversion of flood waters in potential future events. For all areas of the ditch, sediment that was deposited by the flood will be removed and the ditch banks will be reshaped where sloughing occurred. Riprap will be added to portions of the reconstructed ditch banks to prevent erosion and increase protection to the ditch. This solution provides for the most cost effective solution that can be completed in the available construction schedule to restore water supply deliveries. The estimated engineering and construction cost of this Alternative is $600,000 and is further broken down as follows: TABLE 2: PROJECT COST SUMMARY Task Cost Leyden Crossing Engineering, Design and Construction Management $22,000 Leyden Crossing Testing, Survey, & Permitting $15,000 Leyden Crossing Construction $182,000 Cleaning and Sediment Removal Projects $225,500 Subtotal $444,500 Contingency (35 %) $155,500 Total $600,000 Schedule: Construction is expected to commence October 2013 with Project completion by March 2014.