National Program For Inspection Of Non Federal Dams Lower Roberts Meadow Reservoir Dam Ma 00753 Connecticut River Basin Northampton Massachusetts Phase I Inspection Report

Lower Roberts Meadow Reservoir Dam is an earthfill embankment with a maximum height of 22.7 feet and a greatly curved crest, 550 feet long and 10 feet wide. A concrete and stone masonry spillway about 50 feet long, 14 feet high, and a freeboard of 9.3 feet is located near the northeast end of the embankment. Concrete and stone masonry training walls flank the spillay. A concrete low level intake structure with a manully controled slide gate is located about 180 feet west of the spillway. Phase I inspection and evaluation of the Lower Roberts Meadow Reservoir Dam does not indicate conditions which would constitute an immediate hazard to human life or property. Based on engineering judgment and the performance of the earth embankment and the outlet works, the project is considered to be in good condition. The project has a number of deficiencies which, if not remedied, have the potential for developing into hazardous conditions. It is estimated that 23% of the PMF over the combined drainage area could be processed by the combined Middle and Lower Reservoir storage and spillway capacities without overtooping the Lower Dam.

This dam is a 403 foot long, 42 foot high stone masonry structure. The visual inspection did not disclose any findings that indicated an immediate unsafe condition. The city is in the midst of a program of pressure grouting this dam to stop leaking which was extensive. At the time of the inspection, water was still leaking through the dam but at a much lesser rate than previously reported. The dam's spillway will not pass either the PMF or 1/2 PMF without overtopping the dam, and the spillway is not considered adequate. There is an area of standing water existing below the right abutment of the dam. This area should be cleaned and a surface drainage system installed.

Roberts Meadow Upper Reservior Dam is a cut stone masonry and earth gravity dam having a hydraulic height of 35 feet, length of 305 feet including a 150 foot long dike. The stone masonry section is approximately 65 feet wide, is slightly arched in an upstream ddirection, has a crest width of 4.5 feet and serves as the spillway. The 1/2 PMF test flood inflow for Roberts Meadow Upper Reservior Dam, having a drainage area of 8.8 square miles was determined to be 7480 cfs which would overtop the dam by about 3.4 ft. The spillway capacity at the top of the dam is 1500 cfs which is 20 percent of the test flood discharge. The dam itself is in poor condition. The major concerns are: The large amount of leakage through the stone masonry section which has the potential for freezing and dislocating stone blocks in the face of the dam; internal erosion of the earth embankment at the southerly end of the spillway; brush and tree growth on the embankment sections; and a large unstable mass of bedrock overhanging the downstream channel at the northerly abutment.

This dam is a 940 foot long earth embankment dam with a concrete spillway. It is recommended that the areas of erosion both on the upstream and downstream faces where the abutments and embankment interface be repaired. Surface water in these areas should be redirected to prevent future erosion. The riprap on the upstream face should be extended to the dam's crest. The water exiting from the toe and core wall drains should be directed to a control channel and weir where the flow can be periodically measured. The 20-in capped pipe running beneath the dam to the downstream toe should be uncapped and extended to the lower reservoir. This will prevent the potential of a pressurized pipe (should the outlet gate be left open) from bursting and undermining the dam. Although the spillway can not discharge the test flood without overtopping the dam, the spillway capacity is comparatively large. Because of the hydrologic and safety relationships between this dam and the lower reservoir, it is necessary that future hydrologic studies concerning spillway capacities at either project should simultaneously encompass studies for both projects.

The dam is a 1200 ft. long, 23 ft. high earth embankment dam. The visual inspection of the dam did not disclose any immediate stability problems. It is recommended that the seepage condition below the toe of the dam be investigated and an adequate collection and monitoring system be designed.

Lower Glen (Greenfield) Reservoir Dam is a 46-foot high stone masonry dam, spanning the lower portion of a 300-foot deep V-shaped valley. The dam has a crest approximately 95 feet long, a vertical downstream face, a service spillway and an auxiliary spillway. The upstream face of the dam is submerged, and since no construction data are available, the configuration of the upstream side of the dam is unknown. The dam was constructed around 1904 to provide a water supply reservoir for the Town of Greenfield. The reservoir has not been used for water supply purposes for more than 30 years; therefore, the dam now serves no useful purpose. The dam appears to be in poor overall condition. Several joints have opened due to structural movement of the dam as evidenced by a bulge on the downstream face of the dam located just to the east of the center dam pier at mid-height. A great deal of seepage was observed at the location of the bulge and toward the east side groin area. The test flood peak inflow to Lower Glen (Greenfield) Reservoir was computed to be 3,760 cfs. The test flood peak overflow is also 3,760 cfs, with a discharge 4.8 feet over the top of the dam. The service and auxiliary spillways have a combined discharge capacity of 740 cfs, or 20 percent of the routed test flood outflow, just prior to overtopping of the dam.

Vistron Dam, also known as Pro Brush Dam is a stone masonry gravity dam across the NMill River. The dam has a hydraulic height of 24 feet, 195 feet long, 8 feet wide at the crest with downstream face battered at approximately 1H: 12V. The spillway section of the dam is 140 feet long. The dam is founded on bedrock which is exposed at the southwesterly abutment and along the base of the dam. The dam is presently in good condition with no major problems. The main deficiency noted is the presence of trees growing near the top and out of the side of the dry laid stone retaining wall at the northeasterly abutment. Considering a 20,000 cfs inflow, from the 52 square mile drainage area, and assuming no downstream controls, the dam would be overtopped by approximately 4 feet. Spillway capacity at the top dam is 10,500 cfs which is approximately 4 feet. Spillway capacity at the top of dam is 10,500 cfs which is approximately 52 percent of the 1/2 PMF.

Wright's Reservoir Dam is approximately 1,000 ft long. It consists of a small earth embankment approximately 14 ft high and an ungated concrete ogee spillway and stilling basin. An 800 ft long dike is present at this facility on the west side of the reservoir. Its maximum height is 12 ft. This facility was constructed in 1964 under the direction of the Corps of Engineers. The dam is generally in good to excellent condition. There are no obvious signs of failure or conditions which would warrant urgent maintenance treatment. Hydraulic analysis indicated that the spillway will pass the spillway test flood without overtopping the dam. The spillway test flood selected for this structure was the probable maximum flood. Recommendations for maintenance work include the clearing of brush and mowing of grass, especially at the west dike and the replacement of the operating handle for the reservoir drain at the outlet works. This work should be performed as part of the regular maintenance of the dam.

Westfield Reservoir Dam is an earthen embankment structure about 350 feet long and 40 feet high. It has an uncontrolled overflow spillway located on the left (east) abutment and a 24-inch diameter cast-iron pipe outlet conduit which passes beneath the dam and which is valve controlled at the outlet end. Based on the visual inspection, the dam is judged to be in air condition. The following deficiencies were observed at the dam: minor but widespread slumping on the downstream slope; an animal burrow on the downstream slope; large trees near both abutments; a soft, wet area along the right bank of the downstream channel; a small sinkhole on the right side of the spillway discharge channel; lack of vegetation on the crest of the dam; inoperable valves on the downstream end of the outlet conduit; and no valve or other means of regulating or shutting off flow at the intake end of the outlet conduit. With the stoplog in place, the spillway capacity of Westfield Reservoir Dam is 707 cfs, which is about 15 percent of the routed test flood outflow of 4670 cfs. With the stoplog removed, the spillway capacity is about 994 cfs, which is about 21 percent of the routed test flood outflow. The test flood would cause the dam to be overtopped by about 3.5 feet.

The dam is a 348 foot long, 51 foot high structure, originally designed and constructed as a masonry gravity dam in 1912. Later, an earth embankment was placed against the downstream face of the original masonry dam. The visual inspection indicates the dam is presently in poor condition. The concrete chute spillway is badly weathered, cracked and undermined in several areas. Should the bottom of the chute lift and plug the shallow height chute discharge opening, events could lead to serious undermining and erosion of the earth embankment. Repairs to correct deficiencies with the mechanical elements in the control tower are now being studied by the owner. Effects of reservoir storage would cause the test flood discharge to be 3,600 cfs which would overtop the dam by about 1.6 feet. Spillway capacity at the top of dam is 940 cfs which is 25 percent of the test flood discharge.