National Program for Inspection of Non-Federal Dams. Deep River Reservoir Dam (CT 00346), Thames River Basin, Colchester, Connecticut. Phase I Inspection Report

摘要

The dam at Deep River Reservoir is a zoned earth embankment approximately 900 feet long, 62 feet high with an average crest width of 20 feet. It was originally constructed in 1926, 7 and raised in 1971, 2 to its present configuration. It is owned by the City of Norwich, Connecticut and operated by the Department of Public Utilities as the main surface water supply of the City. The dam has an agee overflow spillway at the right abutment. The spillway is a converging chute type with a drop to a stilling basin at the toe of the dam. The outlet works and control tower are centered on the embankment and discharges from the tower's wet well flow through a reinforced 42 inch diameter condiut beneath the dam. An earth embankment dike 240 feet long in an adjacent cove of the reservoir contains an erodable fuse plug emergency spillway. As a result of the visual inspection and the review of available data regarding this facility, the dam is considered to be in GOOD condition. To assure the long-term performance of this structure, several items of concern require attention: modifications need to be made to the existing relief well monitoring system in order to more accurately record the seepage flow, a localized erosion immediately upstream of the left abutment of the dam must be repaired, and vegetable growth in the downstream channel of the emergency spillway should be removed. The maximum outflow capacity of the spillway under a stillwater condition is equal to 18,860 CFS which represents more than 100 percent of the test flood.