HAMILTON TOWNSHIP - For nearly a decade, a growing pile of inspection reports has detailed key problems with the Lake Lenape Dam. Officials took steps to fix problems, but the work essentially stalled as officials and contractors traded blame for partial collapse of the repair structure in a February 2011 incident that led to an emergency evacuation of downstream residents.

Now, Atlantic County and Hamilton Township refuse to allow the public to see a publicly funded engineering report that in June described the Lake Lenape Dam as "unsafe."

The state Department of Environmental Protection's Bureau of Dam Safety and Flood Control in Trenton, however, has allowed open access to the report and older files. These files show:

•A hole in the western embankment, nearest the ruins of a former factory, identified by Atlantic County inspectors in 2010 has grown to about 16 inches high and 25 feet wide, extending about 11 feet into the dam. This embankment also may have moved.

•The century-old flood control gates that were replaced during a $1.1 million rehabilitation in 1991 were already only partially functional by 2004. These have not been repaired, and they limit the ability of dam operators to respond to lake water levels.

•The state has had to remind the county and township five times during the past 13 years to make mandatory inspections.

•When they inspected, the county and the township missed their own later deadlines to fix the problems the reports identified, including the flood control gates.

•Once state dam regulators saw the most recent report, the Bureau of Dam Safety and Flood Control in July declared the dam unsafe, ordered the county to start carefully monitoring it, and ordered water levels lowered before significant storms. Township officials said in August the damaged gates made lowering water levels more difficult.

•Any dam failure would affect properties in four communities: Hamilton Township, Egg Harbor Township, Weymouth Township and Corbin City.

John H. Moyle, Dam Safety's manager, said the dam is not in imminent risk of failure. He said the mandated monitoring program includes steps should the dam appear to move.

The structure was classified as "unsafe," he said, to err on the side of caution. About 1,600 dams are in New Jersey, and about six, on average, are declared unsafe every year.

Estimates vary on the impact of dam failure.

In a best-case scenario, the Mill Street Bridge would face a torrent of water running for almost two hours, flowing several feet higher than high tide, according to a 1991 dam break analysis by O'Brien & Gere Engineers of Blue Bell, Pa. Once it reached the broader reaches of Great Egg Harbor River, it would spread out and dissipate.

A 1981 engineering analysis said 52 people lived and more than 525 people worked in the affected area.

The report also identified 18 properties at risk, mostly on streets near the dam. These properties currently include the former mill, a Masonic Lodge, several businesses and 13 residences. Hamilton Township assesses these at just less than $4 million.

The current Emergency Action Plan is broader.

Should the dam fail without a storm - a so-called "sunny-day dam breach" - floodwaters "would impact approximately 75 residential homes and as many as many as one dozen commercial properties."

O'Brien & Gere wrote the worst-case scenario would follow 32.3 inches of rain falling over three days. Atlantic County's flood maps enclosed a broad swath of ground around the dam, including parts of Corbin City and Hamilton, Egg Harbor and Weymouth Townships.

Most of that ground is already within the limits of the Federal Emergency Management Agency's 500-year storm - a storm of such magnitude that it has a 0.2 percent chance of happening any given year.

The township and county acquired the lake and dam in the 1980s from private owners and now share costs. A small portion near the ruins of the factory is controlled by Cotton Mill Associates, a Rumson-based firm that owns that property. An agreement left the township in charge of daily maintenance and the county responsible for more substantial repairs, such as these.

Confronted by the reports, Atlantic County officials said they were working on addressing the problems.

Atlantic County Executive Dennis Levinson said a dispute between the county and the contractor, Agate Construction of Dennis Township, have hampered repairs. The dispute is now in mediation.

Agate was hired in July 2010 to make $1.1 million in repairs, but work largely stopped after a failed sheet piling in March 2011 briefly touched off fears of dam collapse.

"We don't believe the job was done how it had been expected to be done, and we're blaming them," Levinson said.

Records show Agate has said the prepared plans were inadequate, but it did not respond to a request for comment.

Joseph D'Abundo, the Atlantic County engineer, said the county has filed its monitoring reports with the state since being ordered to do so. He expected the engineering firm it hired, URS Corp., to file plans to stabilize the embankment by the end of January or early February.

The Lake Lenape Dam was built between 1846 and 1847. For decades, it powered adjacent mills. When this first structure broke in 1878, the ensuing floodwaters washed away Mays Landing's uptown bridge.

Both dam and bridge were rebuilt. A powerhouse next to the mill opened in 1920. It has needed repairs intermittently though the years.

A 1975 analysis found severely cracked pipes, damage to the spillway and an eroded riverbed. Lake Lenape was essentially drained for several years while crews repaired the dam.

The U.S. Army Corps of Engineers classified the dam as "high hazard" in 1979, during part of a national series of dam inspections. The classification meant its failure probably would kill at least one person and cause widespread damage.

It is Atlantic County's only high-hazard dam. State law requires high-hazard dams to be inspected every two years, or risk being drained and dismantled. However, these inspection reports show many of the same issues, year after year, unrepaired.

In November 2004, a group including Atlantic County civil engineers Douglas DiMeo and Michael N. Ingram, Hamilton Township Public Works employees Oliver Theis and Chuck Faisst, and Atlantic County engineering intern Harold Edwards inspected the dam. Their report found eight issues.

Primarily, only one of the three hand-cranked gates that controlled water flow through the three 48-inch pipes at the base of the dam completely worked. The west gate was stuck shut, they wrote, and the middle gate would not completely close.

Inspectors found cracks, missing stones and erosion, but concluded the dam was safe, needing repairs no later than April 30, 2006.

In December 2007, DiMeo, Assistant Engineer John A. Conover and engineering intern Samuel Pagano found the gates still broken. They also found 11 other issues, including cracks, missing stones and erosion, and wrote repairs should be done by Nov. 30, 2008.

Contract documents showed the county took steps to make repairs in 2008. However, an August 2010 county report showed the dam gates still were broken, and the cracks, missing stones and erosion were unaddressed.

Inspectors also encountered a foot-deep hole by the foot of the fish ladder and observed some of the steel sheeting pushing out.

The county approved a $1 million contract with Agate in August 2010 to repair the gates and fix other problems. Work began several months later.

By late February 2011, Agate crews had installed part of the cofferdam, the artificial structure needed to wall off the lake water and enable workers to fix the pipes.

On Feb. 28, 2011, a Hamilton Township Public Works employee went to the job site and told Agate the lake levels were flooding nearby roads, according to the daily engineering report. After county, township and company officials talked, they decided to lower the water levels by driving the pilings down by 2 feet.

The bottom of the piling buckled about 4:30 p.m., and crews soon saw water rushing down into a new void on top of the dam. Agate crews quickly used a crane to pile three dump truck loads of riprap stone, along with sand-filled sacks, into the opening. Riprap is loose rock that is used to protect embankments from erosion.

Problems worsened the next day. Agate opened auxiliary gates to drain the lake and reduce the volume of water going over the dam. Fearing a dam collapse, local police evacuated downstream residents for several hours.

Agate crews dropped another seven truckloads of riprap stone into three new openings, only stopping when the dam appeared stable after 3:30 p.m.

A report two months later by Agate's engineer Duffield Associates blamed the collapse on the design.

Once the sheet pilings were partially in, water moved quicker in the constricted space, undermining them. The holes that developed on top of the dam were unrelated to the partial collapse, they wrote.

Atlantic County rejected the report as an insufficient explanation, and work has remained largely stalled in the years since.

Township and county officials stonewalled requests for records throughout the year.

Hamilton Township officials initially mentioned this year's URS Corp. survey of the dam in passing at an early May township meeting.

Malcolm Ian McPherson, the assistant county counsel, denied a request to see the report on May 16 because the report was not yet final. Robert S. Sandman, Hamilton Township's solicitor, called it "a preliminary report obtained in anticipation of litigation" when he similarly denied access on June 6.

McPherson again called the report a draft document when he denied access on Sept. 13.

On that same day, Rita Martino, Hamilton Township's deputy clerk, wrote that the county and contractor were in mediation. Consequently, she wrote, any report was protected by "attorney client privilege, work product privilege, the mediation laws and statutes and/or the mediation agreement."

In late October, Hamilton Township Mayor Amy Gatto said the report still was confidential and referred questions to Township Administrator Michael Jacobs.

Jacobs did not return two subsequent calls seeking comment.

On Wednesday, Atlantic County Executive Dennis Levinson said he was shocked that his staff decided the report was off-limits.

"You had to go to Trenton? I want to find out why you had to do that," Levinson said. "We don't have anything to hide. You do those things when you have something to hide."

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