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I I I I I I I I I I I I I I I I I I I east half where the leaks occur was constructed with a blocky clay that was placed in loose, uncompacted lifts. The 1913 report states, "The water was allowed to rise three feet more to elevation 43, when the seepage through the dam became rather alarming". The dam is in the same condition today and when the water was allowed to rise above gage height 42 feet in 1996 it was still alarming and prompted the irrigation company to seek some solution to the problem. The spillway for the dam is located on the east side of the reservoir (right abutment) and is approximately 300 feet in width. The spillway crest varies from gage height 47.4 feet to 43.3 feet. The spillway is a depressed area with an earth channel. There are no erosion control measures at the spillway and the spillway crest is not controlled with a concrete wall or any other measures that would maintain a constant crest elevation. The historic drainage path for the basin and that for the current spillway are not the same. The discharge from the reservoir spillway is across Boulder County Road 10 then on to the north toward the St. Vrain River. The existing spillway diverts the flows across private property prior to the discharge meeting the St. Vrain flood plain. The historic drainage path was through the reservoir basin and discharged into the St. Vrain flood plain approximately Ih mile to the west of the current location. The deficiencies for the dam associated structures is as follows. 1. Seepage through the dam embankment and dam foundation. 2. Uncontrolled spillway crest with no erosion control measures. 3. Spillway that does not meet the State Engineer's requirements to discharge into the historic drainage basin. The intent of the Company is to address the above deficiencies and rehabilitate the dam such that it meets current standards and requirements of the State Engineer. A more complete discussion of the dam, its associated structures, and recommended repairs is included in Appendix H of this report. ALTERNATIVES EVALUATED A range of alternatives were considered as outlined below. Alternative 1) Includes placing a drainage blanket over the upstream face of the dam from approximately gage height 40 feet to the dam toe, installing a toe drain at the downstream toe, and constructing a spillway which meets the State Engineer's requirements. Alternative 2) Includes placing a pve liner on the upstream face of the dam, a toe drain at the downstream toe, a narrow drainage blanket at the downstream toe, and constructing a spillway that meets the State Engineer's requirements. Foothills Dam- 96.014 Page 4