National Program For Inspection Of Non Federal Dams Highland Lake North Outlet Nh 00238 Nhwrb 24507 Merrimack River Basin Washington New Hampshire Phase I Inspection Report

The dam is intermediate in size with a low hazard potential. The hydraulic analyses indicated that the spillway test flood in Highland Lake is 11800 cfs, of which the North Outlet would experience 3950 cfs. It is recommended that the refined hydrological analyses elsewhere recommended for Highland Lake's South Outlet be undertaken. (Author).

The dam is about 9 ft. high, and is a concrete and stone gravity dam which is founded on rock. The dam is classified as intermediate in size with a significant hazard potential. The condition of the dam is fair, although some preventive maintenance items require attention. The dam has successfully withstood major floods in the past without evident distress. (Author).

The Souhegan River Watershed Dam No. 26 is located on Blood Brook, a tributary of the Souhegan River, approximately 2 miles upstream of West Wilton, New Hampshire. The dam is an earth embankment 692 feet long and 79 feet high with a drop inlet service spillway structure and a 30 inch outlet conduit. An emergency spillway 320 feet wide is cut into the left abutment.

Mountain Pond Dam is located on the north end of Mountain Pond in Sanbornton, N.H., in mountainous terrain two miles south of the village of New Hampton. The dam is an earth embankment, 97 feet long and 14 feet high with a gated 8-inch outlet. The impoundment stores the water supply for the Town of New Hampton and is also the fire protection reserve. It is small in size with a low hazard potential. The test flood is in the range of a 50 to 100 year frequency. The condition of the dam is considered to be fair, requiring that modifications be made by the owner within 1-2 years after receipt of this inspection report. Keywords include: Inspection, Dam safety, Merrimack River Basin, Sanbornton, New Hampshire, and Tributary of Pemigewasset River.

The dam is a 188 ft. long, 16 ft. high earth embankment dam. The condition is fair. The visual inspection did not disclose any immediate safety problems. The dam's spillway will not pass the test flood, therefore it is recommended that the owner engage a qualified engineer to evaluate further the potential for overtopping the inadequacy of the spillway. (Author).

Chase Pond Dam is a rock filled log crib with timber planking overflow structure between stone and concrete embankments. The overall length of the dam is 103 ft. The timber overflow section is approximately 12 ft. high by 50.5 ft. long and 10 ft. wide at the crest. The embankments, which are approximately 5.4 feet higher than the crest of the timber overflow section, are composed of masonry and concrete on the upstream and training wall faces. As a result of the visual inspection of this facility, the dam is considered to be in poor condition. The dam is small in size with a significant hazard classification. The dam at the outlet from Tannery Pond could be overtopped or breached. Keywords include: Inspection, Dam safety, Merrimack River Basin, Wilmot, New Hampshire, and Chase Pond.

Sanborn Pond Outlet dam is an earthen embankment structure about 265 feet in overall length and a maximum height of 16.5 feet from crest of dam to downstream toe. The upstream and downstream faces consists of a 2 feet thick vertical dry stone masonry wall which extends the full height of the dam. Located about 105 feet from the left abutment is the principal spillway which consists of a 19 feet long spillway structure with vertical dry masonry training walls and flashboards. The dam in considered to be in poor condition with some major concern which must be corrected. It is intermediate in size with a significant hazard potential. Keywords include: Visual inspection, Dam safety, Merrimack River Basin, Louden, New Hampshire, and Sanborn Brook.

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 a 404 ft. long, earth-filled rock crib which incorporates a 58 ft. long spillway and a 42 inch diameter steel pipe outlet controlled by a stoplog weir. It is intermediate in size with a significant hazard potential. The dam is in poor condition at the present time. The dam requires considerable maintenance. (Author).

The Souhegan River Watershed Dam No. 10A is located on Mill Brook approximately one mile upstream of Davisville, N.H. The dam is an earth embankment 951 feet long and 59 feet high with a drop inlet service spillway structure and a 30 inch outlet conduit. An earth emergency spillway 220 feet wide is cut into the left abutment. An earth emergency spillway 110 feet wide is cut into the right abutment. The dam is intermediate in size with a high hazard potential. The dam is in good condition at the present time. It is recommended that the owner retain the services of a registered professional engineer to investigate the cracking and erosion of the outlet conduit. Keywords include: Visual inspection, Dam safety, Merrimack River Basin, Wilton, New Hampshire, and Mill Brook, a Tributary of the Souhegan River.