National Program For Inspection Of Non Federal Dams Red Dam Ma 00170 Charles River Basin Wrentham Massachusetts Phase I Inspection Report

Weston Reservoir Dam is an earth embankment approximately 1,000 feet long with a maximum height of about 32 feet. Discharge from the reservoir is controlled by a system of 5 stop log bays, which are located in the stone masonry screen chamber and flow control building located about 50 feet to the right of the left abutment. A 16-inch low level discharge pipe, located about 500 feet to the left of the right abutment, provides additional discharge capacity. No spillway exists for this structure. The test flood peak inflow to Weston Reservoir was computed to be 1,880 cfs. The routed test flood outflow was computed to be 1,100 cfs and would result in overtopping of the embankment to 0.5 feet. The reservoir is capable of storing approximately 60 percent of the test flood in surcharge storage prior to overtopping of the embankment.

Chestnut Hill Reservoir Dam is an 82-year old earth embankment structure used as a reserve source of water for the City of Boston water distribution system. The embankment is approximately 2,000 feet long with a maximum height of about 18 feet and a top width of 20 feet. The dam is considered to be in fair condition. Saplings have been recently planted on the downstream face, it is not known if the gates and gate valves in Effluent Gatehouses 1 and 2 are operable, many animal burrows were observed on the downstream face and the catch basin system at the downstream toe of the embankment appears to be completely plugged. The test flood for the facility is 22.9 inches of rainfall falling directly on the reservior. Since the reservior surface level is constantly maintained as close as possible to the normal level, which is 4 feet below the top of the dam, chances of the embankment being overtopped during the test flood event are extremely remote.

The embankment surrounds the reservoir for a distance of about 1100 ft. The dam is small in size with a hazard potential of high. The dam is judged to be in fair condition at the present time owing to the apparently inoperative lower sluice gate, riprap failures in the interior face and excessive vegetation on the interior and exterior faces. (Author).

Cedar Swamp Pond dam, which was constructed in 1939, consists of an 11 foot high concrete spillway combined with an 8 foot high earthfill embankment. The concrete ogee-type spillway is about 100 feet long. The outlet control is comprised of two 4-foot square steel slide gates located in the left abutment of the spillway section. Based on the visual inspection, drawings available for the dam, and past operational performance, it is judged that Cedar Swamp Pond Dam is in good condition. However, there are a number of problems which should be corrected. These include: local erosion of the dam slopes, large trees on the dam embankment, spalling of the spillway concrete, and an accumulation of weeds, soil, and debris in the downstream channel. It was also noted that the access plates to the flashboards on the spillway deck are welded shut. Hydraulic analyses indicate that the existing spillway can discharge a flow of 2,840 cubic feet per second (cfs) at Elevation (El) 272.5 which is the minimum top of the dam. The spillway is adequate to discharge the inflow test flood of 3,513 cfs (one-half of the probable maximum flood) without significantly overtopping the main dam.

Patch Reservoir Dam consists of a stone masonry spillway and earth dike. The spillway is about 6 feet high and 70 feet long. The earth dike has a maximum height of 11 feet and is about 200 feet long. Generally, the dike and spillway are considered to be in fair condition. Based on size and hazard classification, the test flood is considered to be one half of the PMF.

The dam is a 830 foot long, 32 foot high earth dam with a 40 foot wide stone masonry spillway near its right. The dam is in fair condition. The size of the dam is intermediate and the hazard classification is high. Also various remedial measures should be taken by the owner.