National Program for Inspection of Non-Federal Dams. Grupes Reservoir Dam (CT 00057), Connecticut Coastal Basin, New Canaan, Connecticut. Phase I Inspection Report PDF Download
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Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Book Description
The dam, built in 1871, is a 225 foot long stone and mortar masonry gravity dam used for water supply. There are two spillways; a main spillway section at the left end of the dam and an auxiliary spillway approximately 40 feet upstream from the right end of the dam. The two outlets are 24 inch and 16 inch cast iron pipes. The 24 inch pipe is located at the left end of the dam and serves as a low-level outlet or a supply line. The 16 inch pipe is located at the right end of the dam and is used as an emergency supply line. Based upon the visual inspection at the site and past performance, the dam is judged to be in fair condition. The masonry of the dam and training walls appears to be in fair condition. There are areas requiring maintenance and monitoring such as cracks in the mortar joints of the masonry in the dam and spillway walls and seepage at the right end and central portion of the dam. The spillway capacity with the reservoir level to the top of the dam is 2900 cfs, which is equivalent to 18% of the PMF outflow. The spillway capacity does not include flow over the low area in the service road.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 124
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Book Description
The dam, built in 1871, is a 225 foot long stone and mortar masonry gravity dam used for water supply. There are two spillways; a main spillway section at the left end of the dam and an auxiliary spillway approximately 40 feet upstream from the right end of the dam. The two outlets are 24 inch and 16 inch cast iron pipes. The 24 inch pipe is located at the left end of the dam and serves as a low-level outlet or a supply line. The 16 inch pipe is located at the right end of the dam and is used as an emergency supply line. Based upon the visual inspection at the site and past performance, the dam is judged to be in fair condition. The masonry of the dam and training walls appears to be in fair condition. There are areas requiring maintenance and monitoring such as cracks in the mortar joints of the masonry in the dam and spillway walls and seepage at the right end and central portion of the dam. The spillway capacity with the reservoir level to the top of the dam is 2900 cfs, which is equivalent to 18% of the PMF outflow. The spillway capacity does not include flow over the low area in the service road.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 103
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Book Description
The dam at New Canaan Reservoir is an earth embankment approximately 445 feet long, 37 feet high and having a top width of 21 feet. Built originally about 1898 with subsequent modification from 1929 to 1942, this dam impounds water used by New Canaan, Connecticut. The New Canaan Water Company presently owns and operates the dam including its water works facilities. Based on the visual inspection and past operational performance, the dam is judged to be in fair condition. Seepage was noted on the downstream face. The emergency outlet works have not been operated in some time. The two service bridges were found to be in need of repair. Trees were recently cut on the downstream face and the slope is in an unvegetated state. This dam is classified as small in size and a high hazard potential structure in accordance with the recommended guidelines established by the Corps of Engineers. The test flood for this dam is the Probable Maximum Flood (PMF). The test flood has an outflow discharge equal to 1820 cfs and will overtop the dam by 1.1 feet in a stillwater condition. The maximum outflow capacity of the spillway under stillwater conditions is 240 cfs, which is approximately 13 percent of the test flood. It is recommended that the following items be studied further: The location, condition, and operability of various outlet works; downstream seepage; the composition and adequacy of the dam embankment; the stumps from recently cut trees on the downstream face of the dam; and the deteriorated condition of the service bridge to the gate house.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 91
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Book Description
The project, built in 1904, consists of an earthfill dam, a spillway and an earthfill dike. The total length of the project is 760 feet. Both earthfill structures have a concrete corewall which is founded on bedrock. The spillway, located 60 feet from the left side of the dam is a 30 foot long rubble masonry weir with a 12 to 16 inch thick concrete cover and concrete training walls. The outlet facilities are a 30 inch diameter low-level outlet and a gatehouse located on the downstream toe of the dam. The gate valve is operable. The dam is judged to be in fair condition and the dike to be in poor condition. No evidence of instability of the dam embankment or appurtenant structures was observed. There are areas requiring attention, maintenance and monitoring, such as seepage problems which may occur or may be occuring with the new water surface now to the top of the recently installed stop-planks, which is very close to or higher than the corewall. No evidence of instability of the dike embankment was observed. However, brush and trees on the crest and downstream slope could cause seepage through the embankment. The spillway capacity with the stop-planks removed is 1120 cfs or 23% of the routed test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 95
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Book Description
The 560 foot long dam is an earth embankment with a masonry and concrete corewall. The top of the dam is 10 feet wide and, at elevation 299, is roughly 29 feet above the streambed of an unnamed tributary to the Menunketesuck River. Upstream and downstream slopes are at two horizontal to one vertical and three horizontal to one vertical inclinations, respectively. A stone filter and underdrain runs along the downstream toe of the dam on both sides of the spillway. The 40 foot wide spillway may be described as a broadcrested concrete weir of trapezoidal cross-section. The concrete spillway wingwalls were extended vertically and horizontally by means of gabions when the downstream slope was flattened in 1973. The channel bottom below the concrete spillway apron is lined with gabions, as are the channel sides. There is also a 16 inch diameter low level outlet pipe and a 6 inch diameter low level outlet pipe through the dam from the concrete intake structure to the downstream channel. There is also a 16 inch diameter low level outlet pipe which runs directly from the reservoir through the intake structure and dam to the downstream channel. Based upon the visual inspection at the site and its past performance, the dam appears to be in good condition. No evidence of instability was observed in the dam or it appurtences. There are some areas of seepage requiring monitoring. Based upon our hydraulics computations, the spillway capacity is 920 cubic feet per second (cfs), which is equivalent to 36 percent of the routed Test Flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 74
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The dam is a linear concrete gravity structure with a central spillway. The upstream face of the dam is vertical. The stream face is vertical for 7.5 feet below the top of the dam and then slopes of 7 horizontal to 10 vertical. The spillway is concrete with an ogee shape. Based on the visual inspection of the site, review of available information and past performance of the dam, the dam is judged to be in good condition. The spillway will pass the test flood without overtopping the dam, and therefore the spillway capacity is adequate. Additional investigations to further assess the adequacy of the dam and appurtenant structures do not appear necessary. Patching of deteriorated concrete, initiated by the owner, should be continued. Additionally, during periods of unusually high precipitation, round the clock surveillance should be provided.
Author:
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ISBN:
Category : Science
Languages : en
Pages : 1176
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Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 105
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The dam at Gorton Pond is an earth embankment with the crest approximately 225 feet in length including a spillway length of 62 feet. The dam consists of a 120 foot long main embankment, an overflow spillway and a 1-2 foot high earthen berm to the right of the spillway. The main embankment has a riprap crest and a downstream rock shell to a 1 1/2:1 slope. This section was reportedly designed to withstand occasional overtopping during high flows, however, no design data was found in the available files to substantiate this. The maximum height of the dam is 10 feet. The spillway is an uncontrolled concrete ogee weir and is located about 43 feet from the right dam abutment. The outlet works consists of a sluice gate controlled 36 inch square outlet and is located near the center of the embankment section. The sluice gate is manually operated. The dam has a storage capacity of 450 Ac-Ft at the spillway elevation of 27.0 NGVD and the reservoir and dam are used for recreation. The maximum spillway capacity is equal to 450 CFS which represents only 11% of the test flood outflow, therefore, the spillway capacity is considered inadequate.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 96
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Book Description
Being one of two structures impounding water at the Farm Brook Site 2 Reservoir (See Farm Brook Site 2A Dam CT-01546 Report) the Farm Brook Site 2B Dam consists of an earth embankment approximately 1,000 ft. long with a top width of 14 ft. and a maximum height of 28 ft. The low level outlet for the project is the principal spillway which consists of a three-stage reinforced concrete intake riser, a 30-inch reinforced concrete pipe and a 16 ft. long impact basin. In addition to the low-level outlet, there is a 90 ft. wide, grassed trapezoidal channel at the east end of the dam serving as the emergency spillway. Based on the visual inspection and review of available plans and reports, Farm Brook Site 2B Dam is judged to be in good condition, with the exception of the seepage observed flowing from the 8-in. outlet at the west side of the impact basin. Since the reservoir level was very low at the time of inspection, any possible embankment seepage at the dam could not be ascertained. With the water level at the top of the site 2B Dam, the maximum spillway capacity is 3800 cfs which is 205% of its routed outflow 1850 cfs. The storage capacity of the reservoir at the top of the dam is 1190 ac. ft.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 131
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The Lake Naraneka Dam, constructed in 1937 for recreational purposes, is a 156-foot-long and 18-foot-high concrete gravity dam which is arched in plan. The dam is 4 feet wide at the crest; has a 0.1H:1V sloped upstream face; and a downstream face which is inclined at approximately 0.65 H:1V. The spillway is incorporated into the left side of the dam. The 11-foot-long spillway, located about 30 feet from the left abutment, discharges into a 60-foot-long stone paved channel. Discharge from the site may also pass through the manually controlled 14-inch diameter low level outlet of the 2-inch and 8-inch diameter conduits that supply and drain the small masonry pool at the downstream toe of the dam. The visual inspection of the dam indicated that the structure is in fair condition. Seepage and wet areas were observed on the downstream face of the dam. Extensive efflorescence, cracking and spalling of the concrete was noted at many areas on top, upstream, and downstream faces of the dam. The Lake Naraneka Dam has a top of dam storage capacity of 675 acre-feet (ac-ft) and is approximately 18 feet in height. The capacity of the spillway, with the water surface at the top of the dam, is 215 cfs or 43 percent of the routed test flood outflow. As a result, the dam will be overtopped by 0.7 feet.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 121
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The entire structure is 235 feet long and consists of a 90-foot-long, 14-foot-high earth embankment extending from the right abutment, a 25-foot-long, 10-foot-high concrete broad-crested spillway weir, and a 120-foot-long 14-foot-high embankment span between the spillway and the left abutment. The top of the embankment is approximately 14 feet wide and is 4 feet above the spillway crest elevation of 327 NGVD. The outlet facilities consist of a 24-inch gated conduit at the base of the concrete spillway and an 18-inch ungated conduit in the left embankment. Visual inspection of the dam indicated that the dam is in poor condition. The inspection revealed considerable spalling and efflorescence of the spillway training walls, an inoperable low-level outlet, heavy vegetation on the dam, and evidence of seepage along the toe of the embankments. The test flood outflow is approximately 1,670 cfs; and the capacity of the spillway, with the water surface at the top of the dam, is 620 cfs or 37 percent of the routed test flood outflow. Therefore, the dam will be overtopped by about 1.2 feet.
