National Program for Inspection of Non-Federal Dams. Ashford Lake Dam (CT 00462), Thames River Basin, Ashford, Connecticut. Phase I Inspection PDF Download
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Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 85
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Book Description
The dam, built in 1949, consists of an earth embankment with a spillway at the right end and a low-level outlet at the central portion. The dam has a maximum impoundment capacity of 715 acre-feet and is approximately 450 feet long, 20 feet wide at the top (elevation 667.8) and 26.5 feet in height above the streambed of the outlet discharge channel at the toe of the dam. The top of the dam is an unpaved road, the downstream slope is covered with brush and the upstream slope has dumped riprap to within 3 feet of the top with a growth of weeds on the remaining portion. The spillway is a 15 foot wide earth and gravel channel with 6 foot high concrete abutment walls, and is located at the right end of the dam. The outlet is located at the central portion of the dam, is gated upstream, and has a rectangular outlet measuring 2.0 feet by 1.5 feet, downstream invert elevation 641.3. Based upon the visual inspection at the site and past performance, the dam appears to be in fair condition. There are signs of settlement of the concrete gate structure and extensive cracking and horizontal movement at the spillway concrete abutment walls. There are also areas requiring maintenance and monitoring such as seepage at the toe of the dam, erosion of the upstream slope above the riprap, potholes and ruts in the top of the dam and depression area on the downstream slope. The spillway capacity with the lake level to the top of the dam is 650 cfs, which is greater than 100% of the routed test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 85
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Book Description
The dam, built in 1949, consists of an earth embankment with a spillway at the right end and a low-level outlet at the central portion. The dam has a maximum impoundment capacity of 715 acre-feet and is approximately 450 feet long, 20 feet wide at the top (elevation 667.8) and 26.5 feet in height above the streambed of the outlet discharge channel at the toe of the dam. The top of the dam is an unpaved road, the downstream slope is covered with brush and the upstream slope has dumped riprap to within 3 feet of the top with a growth of weeds on the remaining portion. The spillway is a 15 foot wide earth and gravel channel with 6 foot high concrete abutment walls, and is located at the right end of the dam. The outlet is located at the central portion of the dam, is gated upstream, and has a rectangular outlet measuring 2.0 feet by 1.5 feet, downstream invert elevation 641.3. Based upon the visual inspection at the site and past performance, the dam appears to be in fair condition. There are signs of settlement of the concrete gate structure and extensive cracking and horizontal movement at the spillway concrete abutment walls. There are also areas requiring maintenance and monitoring such as seepage at the toe of the dam, erosion of the upstream slope above the riprap, potholes and ruts in the top of the dam and depression area on the downstream slope. The spillway capacity with the lake level to the top of the dam is 650 cfs, which is greater than 100% of the routed test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 119
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The dam completed in 1963 to impound a recreation pond, is an earth embankment approximately 650 feet in length with an emergency spillway at its left end. It is approximately 40.5 feet in height and is capable of impounding 600 acre-feet of water. The principal spillway is a drop inlet type structure consisting of a reinforced concrete riser with a 42 inch diameter reinforced concrete outlet pipe which discharges to the natural streambed of Goss Brook at the downstream toe of the embankment. A 30-inch diameter low-level intake and sluice gate are also included in the principal spillway structure. The grass-bottomed emergency spillway channel is cut into natural ground at the left end of the dam and has a crest length of 120 feet. The upstream slope of the embankment includes an 8 foot wide berm at the normal pool elevation and is protected by riprap to 2 feet above the berm. The top and slopes of the dam are grass covered, with a filter blanket at the toe of the downstream slope. Based upon the visual inspection and past performance, the project is judged to be in fair condition. There are items which require maintenance or evaluation, such as possible slight tilting of the concrete principal spillway structure and potential for erosion of the emergency spillway embankment. The combined spillway capacity with the pond level to the top of the dam is 4,700 cfs, which is equivalent to 150% of the routed test flood outflow.
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Category : Science
Languages : en
Pages : 492
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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.
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ISBN:
Category :
Languages : en
Pages : 1140
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Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 103
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Andover Lake Dam is an earth embankment dam with a concrete parapet wall along most of its crest. The dam is about 454 ft. long and 20 ft. high. To the right of the dam the reservoir rim has a saddle whose low point is 1.25 ft. below the level of the parapet. A 39 ft. wide concrete spillway with a 7 ft. wide stop-log notch is located about 50 ft. from the left abutment. A 24 in. dia. outlet pipe through the embankment is controlled by a gate valve, which at the time of the inspection was completely submerged. The dam is judged to be in generally fair condition. At the time of the inspection vegetative growth had invaded the embankment, there were cracks in the abutment walls of the spillway, and the spillway's discharge channel was encroaching on the toe of the dam embankment for a distance of about 150 ft. The discharge channel for the low level outlet was in need of repair and had an area of persistent seepage. The top of the embankment was lower than the top of the concrete parapet wall. There was some displacement of riprap on the upstream slope and areas of local erosion on the downstream slope. The spillway can pass about 280 cfs or about 9 percent of the routed test flood outflow without overtopping the low point near the right abutment.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 95
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Eagleville Lake Dam is an earth embankment structure with a masonry spillway. The impoundment, Eagleville Lake, was formerly used for industrial power and process water but is now used for recreation only. The dam was constructed around 1860. Records indicate failure of the right embankment by overtopping from storms in 1938 and 1955. Reconstruction followed each failure. The dam is 22 feet in height and approximately 350 feet in length (including the spillway). The masonry spillway has a crest length of 170 feet. The outlet works is located at the left abutment of the spillway and is constructed of mortared stone masonry. A recently installed 42 inch square gate (1970) is the outlet works for the reservoir. Due to its age, Eagleville Lake Dam was neither designed nor constructed by present state-of-the-art procedures. Based upon the visual inspection at the site and the lack of engineering, operational and maintenance data, there are areas of concern which must be corrected to assure the long-term performance of this dam. The dam is considered to be in FAIR condition. Deficiencies include trees growing on the dam embankment, the potential for overtopping due to the limited discharge capacity of the overflow spillway, and erosion areas on the embankments. All these deficiencies can cause failure of the dam. The maximum spillway discharge of 11,300 CFS represents only 31 percent of the test flood outflow.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 89
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The dam at Deep River Reservoir is a zoned earth embankment approximately 900 feet long, 62 feet high with an average crest width of 20 feet. It was originally constructed in 1926, 7 and raised in 1971, 2 to its present configuration. It is owned by the City of Norwich, Connecticut and operated by the Department of Public Utilities as the main surface water supply of the City. The dam has an agee overflow spillway at the right abutment. The spillway is a converging chute type with a drop to a stilling basin at the toe of the dam. The outlet works and control tower are centered on the embankment and discharges from the tower's wet well flow through a reinforced 42 inch diameter condiut beneath the dam. An earth embankment dike 240 feet long in an adjacent cove of the reservoir contains an erodable fuse plug emergency spillway. As a result of the visual inspection and the review of available data regarding this facility, the dam is considered to be in GOOD condition. To assure the long-term performance of this structure, several items of concern require attention: modifications need to be made to the existing relief well monitoring system in order to more accurately record the seepage flow, a localized erosion immediately upstream of the left abutment of the dam must be repaired, and vegetable growth in the downstream channel of the emergency spillway should be removed. The maximum outflow capacity of the spillway under a stillwater condition is equal to 18,860 CFS which represents more than 100 percent of the test flood.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 85
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North Grosvenordale Pond Dam is a composite masonry and earth dam consisting of two downstream stepped, ashlar faced masonry overflow sections, a granite block and earth fill right abutment and an earth fill right abutment and and earthfill dike on the left abutment. The entire length of the dam is about 2,400 ft. It is a run-of-the-river dam which once served the industrial needs of the downstream mill. Outflows through the millrace are now used for fire protection of the mill. North Grosvenordale Pond is about 1.5 miles long and has a surface area at spillway level of about 60 acres. The drainage area above the dam is about 99 sq. mi. and the maximum storage to the top of the dam is estimated at about 840 acre-ft. The dam is judged to be in generally fair condition. At the time of the inspections, water was flowing over the right spillway, so that it was not possible to observe the condition of the downstream ashlar face, or to determine whether there is any erosion at the toe of the spillways. The crest of the left spillway is higher than the right spillway. The difference is less than 6 in. The sluiceway through the left spillway is inoperative. Some of the left spillway stones have been dislodged and displaces. Several joints in the training walls are in need of repointing. The bridges over the spillways are in a deteriorating condition. Tree and brush growth is abundant along the left abutment dike. The spillways are not adequate to pass the 1/2 PMP test flood of 25,400 cfs without overtopping the non-overflow sections of the dam. The test flood would overtop the dike by about 2.2 ft. The spillway can pass 4,950 cfs or about 20 percent of the test flood without overtopping the dike.
Author: CORPS OF ENGINEERS WALTHAM MA NEW ENGLAND DIV.
Publisher:
ISBN:
Category :
Languages : en
Pages : 110
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The dam consists of a concrete principal spillway, embankments to the right and left of this spillway and an emergency spillway near the right end of the dam. The principal spillway is a concrete chute with weir-boards at the upstream end and the emergency spillway is an unlined channel cut into the right end of the embankment. A swale, which will overflow to the toe of the dam at approximately the same elevation as the auxiliary spillway, exists at the left end of the dam. There is no low-level outlet at the dam. Based upon the visual inspection at the site and past performance, the dam appears to be in fair condition with items which require repair, maintenance and monitoring. These include spalling of the concrete walls at the principal spillway, seepage through the embankments, trees and brush on the embankments and in the emergency spillway, erosion of the upstream slopes, extending the embankment to fill the swale at left end of the dam, and debris and overhanging brush in the spillway discharge channels. The total spillway capacity at the same pool level is 820 cfs, which is greater than 100% of the routed test flood outflow.
