National Program For Inspection Of Non Federal Dams Indian Orchard Ma 00722 Connecticut River Basin Springfield Ludlow Massachusetts Phase I Inspection Report

The dam is generally comprised of a 401-foot long, 10 to 28 foot high main spillway, a head gate building, an overflow canal spillway and a canal leading to two 8 foot diameter penstocks used in electrical power generation. There are two inoperable gates located in the main dam. The dam is normally operated with two feet of flashboards above the spillway crest. The visual inspection did not disclose any findings that indicate an immediate unsafe condition. The 1 /2 PMF test flood used will produce an inflow/outflow of 70,830 cfs. The dam is a run-of-the-river type and the spillway crest would be overtopped by about 14 feet. The spillway has a capacity of 29,500 cfs (42 percent of 1/2 PMF outlfow) at elevation 166.6, top of non-overflow section. The non-overflow section is overtopped by about six feet. This flow would not overtop the upstream training walls which are at elevation 174.0. The overall condition of the dam is considered fair due to the lack of adequate draw down capacity. Remedial measures consist of removing vegetation from the downstream face of the dam, further observation of seepage at the right abutment, repair the wooden crest cover, and develop a formal warning system to warn downstream areas in case of an emergency.

It is a 1900 ft. long earthfill embankment having a maximum height of 26 ft. There are deficiencies which must be corrected to assure the continued performance of the dam. The dam has been classified as small in size having a high hazard potential. Repair of the existing animal burrows should be conducted immediately by the owner. (Author).

Silver Lake Dam is an earthfill embankment about 85 feet long, 12 feet high with a crest width averaging about 30 feet. The project appears to be in fair condition. Since the dam is classified as small in size, with a significant hazard potential, the test flood is one half the PMF. (Author).

The Van Horn Park Upper Dam is an earth dam about 550 feet long with a maximum height of 32 feet and crest width of 50 feet. The upstream and downstream slopes of the embankment as observed are approximately 1(V): 1.5(H) and 1(V): 2(H), respectively. Both slopes are covered with a heavy growth of trees, bushes, shrubs and ground cover. Located approximately at the center of the dam is an uncontrolled outlet for the pond consisting of a reinforced concrete double box culvert and spillway chute. There is also an uncontrolled low level outlet located at the north abutment. (Author).

Chicopee Reservoir Dam is a 545-foot long, 47-foot high earth embankment dam constructed circa 1926. The spillway is a 44-foot long ogee crest which si located at the right abutment of the dam and has a crest elevation (El) 168.0. The outlet conduits are a 24-inch cast-iron former water supply line and a 30-inch cast-iron blowoff. The following deficiencies were observed at the site: high degree of erosion of the principal spillway chute structure and outlet training walls; erosion gullies on the right abutment above the dam crest; brush growth on the downstream slope of the embankment; and seepage from the left abutment downstream of the dam. Generally, the dam is in fiar condition. The adopted spillway Test Flood is equal to the Probable Maximum Flood which yields a peak test flood inflow of 7565 cfs. Hydraulic analyses indicate that the spillway, without flashboards, with the water surface at the top of the dam can discharge 3,950 cfs which is less than the total routed test flood outflow of 6,450 cfs. Thus, the spillway can discharge 60% of the routed test flood outflow.

North Silver Dam is about 1550 feet long with a maximum height of 76 feet. The dam has a chimney drain and a rock toe for internal drainage. The dam has been classified as intermediate in size with a high hazard potential. The dam is considered to be in fair condition. A major breach of the dam could cause appreciable damage to roads, bridges and residences in the downstream area.

The dam is a run-of-the-river type structure consisting of a 17 ft. high concrete overflow spillway and a 13 ft. high rockfill dike. The total height of the structure is 23 ft. from the top of the dike to the streambed at the toe of the spillway. There are deficiencies which must be corrected to assure the continual performance of this dam. The dam has been classified as intermediate in size with a hazard potential of high.

The dam is basically comprised of 2 stone masonry vertical faced spillways. The main spillway has a length of 69 ft. and a structural height of 32 ft. The secondary spillway has a length of 30 ft. and a height of about 9 ft. The visual inspection did not disclose any findings that indicate an immediate unsafe condition. The size classification is small with a hazard potential of significant. Due to the lack of drawdown capabilities, the dam is considered in fair condition. (Author).