National Program for Inspection of Non-Federal Dams. Porter Reservoir Dam (CT 00014), Hockanum River Basin, Manchester , Connecticut. Phase I Inspection Report.
CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV
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Porter Reservoir Dam is an earth embankment approximately 680 feet long with a maximum height of about 32 feet. The upstream slope of the embankment is approximately 2H1V and is riprap-lined to within 3 feet of the top of the dam. The crest width of the dam is about 15 feet. The spillway consists of a concrete weir located about 75 feet downstream of the reservoir in a 20-foot wide stone-lined channel. The purpose of the dam, which is believed to have been constructed around 1902, is to impound a water supply for the City of Manchester water distribution system. Porter Reservoir Dam has a drainage area of approximately 0.6 square miles, with only about 0.15 square miles draining directly to the reservoir. The maximum storage capacity of the reservoir is 100 acre-feet. The peak inflow and outflow rates for the test flood at Porter Reservoir were computed to be 600 cfs and 570 cfs, respectively. The peak outflow corresponds to a stage of 4.2 feet above the spillway crest, or 1.8 feet below the top of dam elevation. The spillway is capable of discharging 970 cfs and can pass 100 percent of the test flood without overtopping of the embankment. The dam appears to be in fair condition. The upstream and downstream slopes of the embankment are overgrown with brush and trees and the crest of the dam is unprotected from erosion. The masonry of the appurtenant structures is in need of minor repairs at several locations and seepage was observed during the inspection at the outlet structure. Several of the gate valves associated with operations of the dam were inoperable at the time of the inspection.
- Hydrology, Limnology and Potamology
- Civil Engineering