Matawan dam bill to run about $10MDespite poor
condition,
mayor says no danger of failure
Matawan taxpayers are not going to have to foot the estimated $10 million repair bill for the Lake Lefferts and Lake Matawan dams, according to Mayor Robert Clifton.
Clifton also said neither dam is in danger of imminent failure, despite recent inspections that show the two dams to be in poor condition and in need of repair. Needed repairs to each dam are expected to run about $5 million.
"We’re going to look into some state grant money," Clifton said Monday. "At this point it should not cost the borough any money, aside from engineering staff.
"We’ve known since before I became mayor [in the mid-1990s] that there were problems with the dams," he said.
Clifton is not sure why inspection reports have not been submitted to the state since 1993, but noted that the borough engineer and public works employees "have always kept an eye on them."
As far as the delay in submitting reports, the mayor said, "The engineer was told by the Department of Environmental Protection that most towns don’t do them, and they were happy to get ours."
Some restoration plans have already been prepared by the engineering firm of French & Parrello Associates, according to the mayor.
Longtime Councilman James Shea said the county and state were supposed to share in the $900,000-plus cost of the engineering design plans for work on the Lake Lefferts plan, but did not.
"There’s been no neglect," he said, agreeing with Clifton. The restoration "was too costly, and no one else would join us in paying for it."
Shea added that some work was done on both dams following the devastating 1992 nor’easter.
"We’re not concerned that there is going to be any collapse," Clifton said, pointing out that there has been no increase in the dams’ deterioration over the past seven years since the last inspection was conducted, and that the dams "are constantly monitored by the borough."
"If anything does occur," he said, "we will make sure there is no loss of life or property."
The Borough Council planned to discuss the two dam inspection reports, prepared by Borough Engineer Robert Bucco and submitted to the state Dec. 1, at last night’s council meeting, Clifton said.
According to the reports, which are based on Nov. 6 visual inspections and borough information, the two dams are in "poor" condition and in need of repair, but in order to determine the overall stability of both structures, a detailed analysis must be performed.
The biennial dam reports, the first since 1993, were submitted to the DEP’s Division of Dam Safety Dec. 1 in compliance with that agency’s request.
The two dams, Lake Lefferts and Lake Matawan, are the joint responsibility of the borough and the county, according to John Moyle, Dam Safety Section chief.
"They knew there were problems. They were hoping they would go away," Moyle said Friday about why the borough failed to comply with a biennial dam inspection requirement.
In large part because of the failure of eight state dams this year and last — four during Hurricane Floyd in 1999 and four in August in the Sparta area — the state agency sent letters to 700 of the state’s recorded dam owners who have not submitted inspection reports, directing them to do so, Moyle said. There are about 1,600 dams in the state, he said.
As of Friday, about 369 responses had been received, according to Moyle, and were continuing to trickle in. About mid-January the agency will begin reviewing the reports.
John Ritchey, a supervising engineer with the state Dam Safety Section, said the state can order dam owners to make repairs. Legislation that would provide $100 million in loans for dam restoration projects is currently pending in the state Senate, he said. The DEP also has an eight-year-old dam restoration loan program, according to Ritchey, but because of the high number of recent failures, that revolving pot of money is currently empty.
Both of Matawan’s dams were built in the late 1920s and underwent reconstruction. They are both classified as Type I, high hazard, dams because failure of either could result in loss of life. According to the ranking system, failure of Type II, significant hazard, dams, could result in significant property damage, and failure of Type III, low hazard, dams could result in loss of the dams.
Ritchey said both Matawan dams are significant because roadways form the dam embankments. Of the state’s 1,600 dams, 186 are classified as high hazard, he said.
Failure of either dam would damage major roadways and inundate residential areas. With the Lake Matawan dam "there appears to be potential for loss of life and property damage downstream," according to the report.
The Lake Lefferts dam has been overtopped by lake water several times in the past 50 years. The Matawan dam has never been overtopped, according to the report.
Lake Lefferts, named for developer Jacob Lefferts, was created in 1928 by damming Matawan Creek, which flows into Raritan Bay.
The earth-embankment dam is about 16 feet deep and 480 feet wide, with a concrete arch dam spillway tied to a concrete bridge and abutments spanning approximately 24 feet. Ravine Drive runs across the top. The upstream side is supported by a timber bulkhead and the downstream side by a pile-supported timber retaining wall.
The dam has a drainage area of approximately six square miles. Lake Lefferts spans 65 acres.
Should it overflow, "the floodwaters would inundate the downstream flood plain as well as a residential area downstream of the dam," according to the report, and damage two of the borough’s major transportation roadways, Ravine Drive and Aberdeen Road.
Clifton said he planned to ask Bucco for clarification of the residential area at Tuesday’s council meeting.
While the report indicates the designer and actual builder of the Lake Lefferts dam are unknown, it was reconstructed in 1930, 1958 and as recently as 1980. The last formal inspection was in 1988 and the last regular inspection in 1993. The last Phase I inspection was in 1978.
According to Ritchey, a Phase I inspection is done by the U.S. Army Corps of Engineers; a regular inspection is visual, such as the recent one by T&M Associates, Middletown; and a formal inspection is a "step higher" than a regular inspection, with an in-depth look.
Lake Matawan was created in 1923 by damming Gravelly Brook Creek, which flows into Matawan Creek downstream of the Lefferts dam. The dam, which is located across Main Street not far from the train station, was reconstructed in 1925. The builder is unknown.
The Lake Matawan dam is also an earth embankment structure, supported on the upstream side by a timber bulkhead and on the downstream side by a pile-supported timber retaining wall.
The dam is approximately 19.5 feet high and 275 feet wide, with a spillway tied to a concrete bridge and sandstone abutments spanning approximately 38 feet. The abutments are left over from an older stone masonry bridge, according to the report.
According to the report, the dam has a drainage area of 2.6 square miles. The lake is approximately 19 acres in size, about a third the size of Lake Lefferts. A flood inundation map shows that the floodwaters would inundate a residential area downstream of the dam and damage Main Street and Aberdeen Road.
The dam reports, prepared by Bucco’s engineering firm, T&M Associates, recommend several immediate repairs, including underwater inspections of the concrete spillways and low level outlets, and repair of the gate valve and appurtenances for low level outlets.
The reports also recommend immediate removal and repair of deteriorated concrete on the spillways and bridges; removal of vegetation and debris from the Lake Matawan dam embankment areas, spillway and bridge structure; and removal of vegetation and animal burrows from the Lake Lefferts dam embankment areas, and compacting and stabilizing berms.
They also recommend the immediate replacement of the Lake Lefferts dam timber bulkhead and deteriorated timber piles, and planks for the timber retaining wall.
The Lake Matawan dam report recommends the immediate removal of debris from the downstream channel and apron, repair of the downstream concrete apron and the stone wall at the bridge abutments, as well as a geotechnical study to determine the source of seepage through the timber retaining wall.
The reports also recommend long-term improvements to the Ravine Drive sidewalk, roadway and shoulder on the Lake Lefferts dam; and stabilizing downstream roadway drainage outfalls for the Matawan dam.
Finally, they recommend additional studies to ascertain the condition of the dam cutoff and foundation stability of the Lefferts dam; and the dam cutoff, and foundation and structural stability of the Matawan dam.
The Lefferts dam also requires a geotechnical study to determine the source of seepage through the timber retaining walls, as well as an updated emergency action plan and an operation and maintenance manual.