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I I I I I I I I I I I I I I I I I I I Alternate A: Enlarge Crescent Lake, Install New Raw Water Transmission Line, and Upgrade the Existing Water Treatment Plant This alternative involves enlarging the volume of the existing Crescent Lake and combining it with a reservoir to be constructed on the adjacent Powelson property. The existing dam would be extended along the west bank of the Little Thompson River until it could be anchored in bedrock at the south end of the proposed Powelson Reservoir. The dam at this point would exceed 10 feet in height, thereby making this a jurisdictional dam. Water would be drained from the low point of the combined reservoir, transferred to a nearby pump station, and then be transmitted via a new raw water transmission line to the existing water treatment plant. The treatment plant would be expanded with the addition of a second, micro-filtration train to meet the 50 gpm output requirement The combined reservoir would be filled by means of an existing diversion point approximately 200 feet north of Kiowa Road. Crescent Lake would be enlarged and sealed with a liner. The transfer line would extend from the low point near the south end of Powelson Reservoir to a pump station located at the north end of Crescent Lake. From there the transmission line to the existing treatment plant would generally follow Kiowa Road, Wichita, and Cree Court. A surge tank is included in this altemative. This will provide consistent inlet conditions at the water treatment plant, since the transmission line goes over a high point and water flows to the existing treatment plant site may be somewhat variable. Altemate A includes expansion of the water treatment plant at the existing site which is of adequate size to accommodate the expansion and is now zoned for this use. The District has an existing infiltration gallery in use at the treatment plant, which would continue to supply the existing micro- filtration unit. The additional raw water from Crescent Lake/Powelson Reservoirwould be pumped to a high point in Cree Court where it will be discharged into a concrete structure at atmospheric pressure. The water will then flow by gravity to the surge tank. This altemate provides minimal capacity for filling the storage tanks at build-out. It is designed to provide the average daily flow of 50 gpm. The maximum capacity of the expanded water treatment plant is 64 gpm, and the firm capacity is 32 gpm. Firm capacity is defined as the total capacity of a facility minus the largest unit out of operation. Thus, the expanded plant only has capacity to fill the treated water storage tanks if both treatment modules are operational. Land acquisition costs do not apply to the existing Crescent Lake site; and the Powelson site may be available at no cost to the District. 3