National Program for Inspection of Non-Federal Dams. Crescent Lake Dam (CT 00277), Connecticut River Basin, Enfield, Connecticut. Phase I Inspection Report PDF Download
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Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
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Category :
Languages : en
Pages : 68
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Crescent Lake Dam is about 600 ft. long, 12 ft. high and has a crest width of about 15 ft. It is an earthen embankment with a downstream slope of about 2 to 1 and a variable upstream slope. There is no orthodox spillway structure, but an unlined channel in the reservoir bank near the right abutment serves as a wasteway for reservoir spills. An outlet canal takes off from the reservoir about 600 ft. upstream from the left abutment, which has a concrete headwall incorporating a 38 in. wide notch with stoplog slots. There appears to be no other outlet structure. Maximum storage capacity is about 335 acre-feet. Crescent Lake, used now for recreational purposes, is less than a mile long, has a surface of about 36 acres and a drainage area of about two square miles. The dam is in fair condition. There is some seepage along the downstream toe of the embankment, which has large mature trees growing on it. The lack of any outlet gate precludes drainage the lake without breaching the dam. The test flood would not overtop the dam but would reach within 1/2 ft. of the crest and overtop areas of reservoir bank adjacent to both left and right abutments, which appear to be as much as 2 ft. lower than the crest of the dam. It appears that the valley area east of the Penn Central Railroad track which is just downstream from the dam would absorb outflows up to the test flood magnitude without major consequences to downstream interests.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 68
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Book Description
Crescent Lake Dam is about 600 ft. long, 12 ft. high and has a crest width of about 15 ft. It is an earthen embankment with a downstream slope of about 2 to 1 and a variable upstream slope. There is no orthodox spillway structure, but an unlined channel in the reservoir bank near the right abutment serves as a wasteway for reservoir spills. An outlet canal takes off from the reservoir about 600 ft. upstream from the left abutment, which has a concrete headwall incorporating a 38 in. wide notch with stoplog slots. There appears to be no other outlet structure. Maximum storage capacity is about 335 acre-feet. Crescent Lake, used now for recreational purposes, is less than a mile long, has a surface of about 36 acres and a drainage area of about two square miles. The dam is in fair condition. There is some seepage along the downstream toe of the embankment, which has large mature trees growing on it. The lack of any outlet gate precludes drainage the lake without breaching the dam. The test flood would not overtop the dam but would reach within 1/2 ft. of the crest and overtop areas of reservoir bank adjacent to both left and right abutments, which appear to be as much as 2 ft. lower than the crest of the dam. It appears that the valley area east of the Penn Central Railroad track which is just downstream from the dam would absorb outflows up to the test flood magnitude without major consequences to downstream interests.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 86
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The 140 foot long dam is an earth embankment, the top of which, at elevation 154.5, is approximately 15 feet above the streambed of Belcher Brook. A drop inlet at a flow line elevation about 4.5 feet below the top of the dam, is the spillway facility. A wooden gate extending the full 7.5 foot depth of the structure is the low level outlet, however it is apparently stuck in a closed position. The inlet structure feeds an arched brick culvert which has an estimated chord length of 7 feet and an effective depth of approximately 3 feet, due to heavy siltation. A recent partial collapse of the brick culvert where it abuts the downstream low-level outlet headwall caused partial blockage of the culvert as well as an approximately six foot wide cavity and sloughing to the crest of the dam on the downstream slope. Based on the visual inspection at the site and past performance, the dam is judged to be in very poor condition. Evidence of instability was noted in the form of a collapse of the outlet conduit and a subsequent failure of the downstream slope of the dam. There are other areas requiring attention as well. Based upon the hydraulics computations, the spillway capacity is 180 cfs to the top of the dam, which is equivalent to 72% of the routed test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 76
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The dam is an earthfill embankment with a concrete and masonry spillway at the central part of the dam. A new highway embankment for Route 263 was constructed in 1976 just downstream from the dam. The old road is now used as an access to the dam lies just below the crest and extends along the dam from the right abutment to the spillway. The dam is approximately 520 feet long an 8 feet wide at the crest, which is 14 feet above the streambed of Sucker Brook. The spillway consists of a 45 foot long broad-crested concrete weir and a concrete apron which is just below the weir and enclosed by masonry training walls. This apron funnels the water into a 60 inch asphalt coated corrugated metal pipe through the new highway embankment. Based upon the visual inspection at the site and past performance, the dam is judged to be in fair condition. No evidence of structural instability was observed, however there are areas requiring attention such as seepage on the right toe of the dam, spalling of the spillway weir and wet areas and lime deposits on the masonry training walls. Peak inflow to the reservoir is 1250 cfs; peak outflow is 550 cfs with the dam overtopped 0.1 feet. The spillway capacity is 410 cfs., which is equivalent to 75% of the routed test flood outflow. The hydraulic/hydrologic calculations do include the effects of the Route 263 highway embankment and 60 inch culvert.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
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Category :
Languages : en
Pages : 134
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Crystal lake is an earthen embankment dam with a maximum height of 50 feet and a length of 130 feet. The upstream and downstream slopes are faced with riprap. The dam has a water control structure with a 36-inch diameter outlet pipe controlled by two sluice gates and a stop log spillway. The dam impounds Crystal lake which is used for recreational purposes. The lake has a storage volume of 350 acre-feet. Based upon the height of the dam, the size classification is intermediate. The dam is judged to be in generally fair condition. The crest is level, and no lateral movement was observed. The vertical and horizontal alignment of the dam is good. Some minor erosion along the dam adjacent to the left abutment was noted. The riprap paving on the upstream face is in good condition. The rockfill downstream face is also in good condition. Small trees and scrub brush are growing on the upstream and downstream slopes and could cause problems if not removed. The total capacity of the water control structure and the 36-inch diameter outlet pipe is adequate to pass the spillway test flood with a freeboard of 0.8 feet.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 123
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Upper Lake Phipps is impounded by Dam No. 1, an earth embankment dam with a stone masonry corewall, located at the eastern end of the Lake, and Dam No. 2, a stone masonry, concrete, and earth structure located near the southwest end of the Lake. A low causeway located on the north side of the Lake separates the Lake from a smaller pond. Dam NO. 1 has a top width of 10 feet, a maximum height of 29 feet, and a length of 345 feet. The dam consists of two sections separated by a bedrock knob located near the center of the dam. Dam No. 2 consists of a stone masonry and concrete buttress wall with an upstream earth embankment. The dam has a maximum height of 14 feet and an overall length of 190 feet, including a 20 foot long overflow spillway located at the right end of the dam. The spillway consists of a concrete cap on a stone masonry weir with 2.7 feet of freeboard from spillway crest to the top of Dam No. 2; Dam No. 1 is another 0.3 feet higher. Based on the visual inspection, the dams are judged to be in poor condition. Features that could affect the future integrity of the dams are seepage downstream of Dam No. 1 and through the masonry wall of Dam No. 2; brush and trees present on the crests and slopes of both dams; continued erosion and slumping of the upstream slope of both dams; deterioration and movement of the masonry portions of Dam No. 2; and the unknown condition or existence of a low level outlet or blowoff line. The Test Flood inflow of 390 cfs results in a routed outflow of 240 cfs and a freeboard from water surface to the top of Dam No. 2 of 0.4 feet.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
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ISBN:
Category :
Languages : en
Pages : 68
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The dam is located on a tributary of the Connecticut River on the town line of Bolton and Vernon, Tolland County, Connecticut. It is an earthfill structure approximately 625 ft. long with a maximum depth at its center of 26 ft. The crest width varies from 12 to 15 feet. A vertical granite masonry wall extends from the downstream side of the crest to the bed of Lydall Brook below. The visable part of the upstream embankment has a 1 on 2 to 1 on 3 slope with a riprap face. The downstream embankment consists of cobbles and boulders piled against the face of the masonry wall on an approximate 1 on 1.5 slope. The dam is in generally good condition. It appears to be structurally stable at the present time under normal conditions. Based on its small size and high hazard classification in accordance with the Corps' guidelines, the test flood is 1/2 the PMF. The spillway will pass only about 44 percent of the test flood and is considered inadequate. Recommendations to improve dam safety are: (1) Increase spillway capacity; (2) Replace 6-in. discharge pipe and relocate valve; (3) Add riprap near the center on the downstream side; (4) Divert spillway discharge away from the toe of the dam.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 91
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The dam is an earth embankment approximately 10 feet wide at the top and 400 feet long with the top approximately 10 feet above the streambed of an unnamed tributary to Raymond Brook. A central portion of the earth dam is comprised of a high area of natural ground to within a horizontal distance of 20 feet from the left spillway abutment. The spillway is a 15 foot long broad crested concrete weir of trapezoidal cross-section with vertical concrete training walls. The low level outlet is an approximately 1 foot square conduit through the spillway section. The flow through the conduit is regulated by a hand operated submerged gate mechanism adjacent to the upstream face of the spillway section. Based upon the visual inspection at the site and past performance, the dam is judged to be in poor condition. There was erosion evident on the upstream slope and crest of the dam, as well as numerous footpaths on the downstream slope. There were also significant amounts of seepage observed on the downstream slope and along the downstream toe of the dam. Other deficiencies include trees and brush on the dam embankment and a low beach area adjacent to the left end of the dam. Based upon hydraulics computations, the spillway capacity is 180 cfs which is equivalent to 113 percent of the routed Test Flood outflow. It should be noted that the above figures assume the low area at the left end of the dam to be raised to the top of the dam.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 117
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The dam is an earthfill dam about 370 ft. long and 31 ft. high. There are no operable appurtenant structures. The dam is judged to be in fair to poor condition. The test flood falls between the 1/2 PMF and the PMF. There are various significant conditions which should be corrected. Alternatively, the lake should be lowered to a safe level until such time as repairs can be made.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 105
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The dam is approximately 450 feet long on the paved roadway running along the axis of the dam which serves as a town street and is approximately 40 feet wide. With a maximum height of approximately 14 feet, the dam is composed of a downstream dry-laid stone masonry wall with an upstream earth fill. The upstream slopes are inclined gently into the lake and are protected by dumped riprap. The two spillways are actually lowered portions of the roadway. The spillways, each 75 feet long, discharge over the downstream masonry wall and onto a dumped riprap splash apron. The low level outlet is a culvert through the dam from 2 low level sluice gates located at the upstream face of the dam. From this outlet, water is routed either to a small generator in the Union Pin Company factory immediately downstream of the dam, or to a discharge channel alongside the factory and back into the stream. Based on the visual inspection at the site and past performance, the dam is judged to be in fair condition overall. No evidence of instability was observed in the dam or its appurtenances, and the condition of the earth dikes was good. Based upon the size (Intermediate) and hazard classification (High) of the dam in accordance with Corps of Engineers Guidelines, the test flood will be equivalent to the Probable Maximum Flood (PMF). Peak inflow to the lake is 9,500 cubic feet per second (cfs); peak outflow is 6,000 cfs with a freeboard of 1.0 feet to the top of the project. Based on our hydraulics calculations, the spillway capacity is 8,600 cfs, which is equivalent to 143% of the routed test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 66
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Lake Winnemaug Dam is an earth embankment approximately 500 feet long with a maximum height of about 15 feet. The upstream slope of the embankment is approximately 1H:1V and the downstream slope is about 1.5H:1V. The top of the dam is about 20 feet wide and it is a paved road. The overflow drop spillway is located about 100 feet from the right abutment and consists of an 18.5-foot long concrete weir, a cascading step section and a 4-foot high by 10-foot wide culvert through the embankment. The original purpose of the dam is unknown; however, the lake is currently used for recreation purposes. The peak test flood inflow for Lake Winnemaug Dam is 3,460 cfs. The routed test flood outflow of 2,010 cfs overtops the dam by about 0.8 feet. The spillway is capable of discharging 770 cfs or about 38 percent of the routed test flood outflow prior to overtopping of the dam. A breach of the dam would result in a 7.8-foot increase in the stream depth (3.8 feet above the channel banks) at the initial downstream damage area. The dam appears to be in poor condition. Numerous structural deficiencies, such as slope failures, seepage, and toe erosion were observed during the visual inspection. The embankment is overgrown with brush and trees and contains a number of rodent holes. The reservoir cannot be drained in an emergency because the outlet pipe control valve is inoperable.
