National Program for Inspection of Non-Federal Dams. Bearhole Reservoir (MA 00073), Westfield River Basin, West Springfield, Massachusetts. Phase I Inspection Report

摘要

Bearhole Reservoir Dam is a 270 foot long, 34 foot high, earth embankment dam built in 1956 to provide storage and regulate its release as part of the water supply system for the City of West Springfield, Massachusetts. The dam is reported to have a core of select impervious material founded on existing impervious material. The spillway, which is located near the right abutment, is a rectangular concrete box with discharge over the walls on three sides. The spillway weir lengths and elevations are as follows: 6 feet long, El 163.75; 50 feet long, El 165.0; 60 feet long, El 165.25. The outlet conduit for the spillway is a 12 by 12 foot concrete box sluice which discharges to a channel near the downstream toe of the slope. Bearhole Reservoir has a storage capacity of 600 acre-feet with the water level at the top of the dam. The following deficiencies were observed at the site: spalling concrete in the spillway and outlet structure; seepage emanating from the toe drainage system and on both sides of the box outlet structure; brush growth, and tree growth on the downstream slope of embankment; depression in riprap slope on the left side of the outlet channel downstream of the box outlet structure; and broken pavement at the crest of the dam. Generally, the dam is in fair condition. Hydraulic analyses indicate that the spillway, without flashboards, can discharge 6425 cfs which is greater than the total routed test flood of 4770 cfs.