National Program For Inspection Of Non Federal Dams Kelleys Falls Dam Nh 00299 Nhwrb No 15002 Merrimack River Basin Manchester New Hampshire Phase I Inspection Report

Kelleys Falls Dam is a run of the river type dam, with an overall length of 503 feet. Visual inspection of the dam indicated that the dam is in poor condition. The inspection revealed a number of leaks through the mass concrete spillway section, considerable loss of concrete from the spillway section, seepage around the concrete wall on the right side of the dam, and general deterioration of concrete on the abutments and hydro-building. Based on the intermediate size of the dam and the significant hazard classification and in accordance with Corps of Engineers guidelines, the test flood is one half the Probable Maximum Flood (PMF) or 55,900 cfs. The one half PMF outflow overtops the dam by 6.8 feet. With the water level at the top of the dam, the spillway will pass 38 percent of the test flood outflow. It is recommended that the owner engage a qualified engineer to make thorough investigation of the condition of the foundation of the spillway section of the dam, investigate the structural stability of the spillway section and ways to increase the spillway capacity. Also, the owner should remove the flashboards on the dam immediately. Additional keywords: Merrimack River Basin, Manchester, and New Hampshire.

The dam is a gravity structure constructed of split masonry. It is about 80 ft. long and 17 ft. high. The dam is small in size with a significant hazard potential. The dam is in poor condition at the present time. There are remedial measures and studies which should be implemented by the owner as soon as possible. (Author).

The dam is a run of the river type dam. It is 633 ft. long with a maximum height of 35.9 ft. The visual inspection of the dam revealed that the dam is in generally fair condition. Noted were some minor cracking and spalling of concrete on the abutments and the poor condition of the gates and mechanical operators. It is intermediate in size with a significant hazard potential. Keywords include: DAMS, INSPECTION, DAM SAFETY, Merrimack River Basin, Concord, New Hampshire, and Merrimack River.

The dam is a large concrete and stone masonry dam with earth embankments. The overall length is about 500 ft. with a maximum height of 27 ft. The dam is assessed to be in poor condition. Problems include structural cracking of an unknown origin, embankment seepage, and low spillway capacity. A test flood of 23,700 cfs inflow into the reservoir would overtop the dam by about 3.2 ft. (Author).

The earth embankment and concrete gravity dam is considered to be in good condition. It is believed to be safe under normal operating conditions. Based on size and hazard classifications in accordance with Corps guidelines, the test flood is the Probable Maximum Flood. In addition to the long term recommendations, there are several remedial measures which should be implemented immediately. (Author).

The dam is a concrete lined earth and rock fill embankment that is used as a water supply. The dam has a maximum height of 35 ft. It is small in size with a high hazard potential. In the event of a failure, several downhill residences would be threatened. The reservoir is in good condition. No displacement settlement, or other signs of major distress were observed at the reservoir. (Author).

The Souhegan River Watershed Dam No. 13 consists of two earth embankment sections known as the main dam and the east dike. The main dam is 500 ft. long and 13.5 ft. high with a drop inlet service spillway structure and a 30 inch outlet conduit. The east dike is 620 ft. long and 9.5 ft. high with no outlet facilities. An earth emergency spillway 112 ft. wide is cut into the right abutment. It is small in size with a significant hazard potential. The dam is in good condition at the present time. No conditions were observed which require further investigation. There are various remedial measures which must be implemented by the owner. Keywords include: Visual inspection; Dam safety; Merrimack River Basin; New Ipswich, New Hampshire; and Unnamed tributary of the Souhegan River.

The concrete dam is about 180 ft. long and is constructed on a circular arc. It is small in size with a low hazard potential classification. The dam is in fair condition. At the present time, there is no way to draw down the level of the reservoir. A program of annual technical inspections of the dam should be undertaken.

The dam is an earthen embankment structure with a central concrete core wall about 147 ft. in overall length and 9 ft. high from the crest of the dam to downstream toe. The dam is considered to be in fair condition. It is classified as small in size and significant in its hazard classification. (Author).

The dam is an earth embankment structure. The dam is 286 ft. long and 22 ft. high. The condition of the dam is fair in spite of a continued history of seepage through the dam that has not been eliminated by refacing the upstream side of the dam. The estimated PMF would overtop the dam by 6.6 ft. (Author).