National Program for Inspection of Non-Federal Dams. Cheshire Reservoir Dam (CT 00303), Quinnipiac River Basin, Prospect, Connecticut. Phase I Inspection Report

摘要

Cheshire Reservoir Dam is an embankment dam 168 feet long having a maximum height of 18 feet, with a centrally located concrete and stone fill spillway section. The spillway is semi-circular in plan and 74 feet long. The overflow cascades over a series of 16-inch-high steps that discharge to Mixville Brook. The spillway is flanked at each end by concrete training walls. An earth embankment section is on each side of the spillway connecting to high ground at either side. The embankment side slopes are 1 vertical on 2 horizontal. The embankments are grass covered gravel and clay. A 24-in diameter blow-off pipe passes through the dam embankment and outlets at the right spillway training wall. Based on the visual inspection, the Cheshire Reservoir Dam appears to be in fair condition. The grassed slopes are well maintained. The vertical and horizontal alignment of the dam is good. Some erosion and slumping was noted adjacent to both training walls of the centrally located spillway. Several animal holes were noted on both downstream slopes (right and left of spillway). No upstream slope protection was noted along the right side of dam. A wet and spongy area was observed near the downstream toe along the left side of the dam. No piping or boils were noted. The concrete spillway is in poor condition. The surface has areas of extensive spalling, efflorescence, and erosion. The training walls have deteriorated and aggregate is visible. The gatehouse is in good condition. The test flood would overtop the dam by about 1.1 feet. The spillway is adequate to pass about 47 percent of the spillway test flood outflow without overtopping the dam.