National Program for Inspection of Non-Federal Dams. Old Quincy Reservoir Dam (MA 00827), Massachusetts-Rhode Island Coastal Basin, Braintree, Massachusetts. Phase 1 Inspection Report

摘要

Old Quincy Reservoir Dam is an earth embankment with a masonry core wall. The dam is approximately 550 feet long and has a maximum height of 37 feet. The stone masonry channel at the right abutment forms the spillway. The outlet works for this facility consists of a stone masonry intake structure within the reservoir and two 20 inch pipes passing underneath the dam and valved at both ends. The facility is considered in poor condition. Seepage was observed immediately downstream of the toe of the dam. The downstream face of the dam contains stumps, trees and eroded areas. Hydrologic analysis indicates that the routed test flood outflow would be 2,120 cfs at a water surface elevation of 84.10. Due to the irregularities at the crest of the shoreline, the dam would not be overtopped at the test flood stage, but only 400 cfs would be discharged through the spillway while the remaining 1,720 cfs would overflow the northern shoreline of the reservoir. This overbank flow would cause flooding in developed areas.