Okhissa dam focus of dispute
Published 12:00 am Tuesday, February 17, 2004
NATCHEZ &045; A former contractor on the Lake Okhissa project has alleged a federal agency’s unwillingness to remove an extra four feet of soil from the dam has damaged the structure &045; and could lead to its failure.
&uot;As a contractor, I’m obligated to build a safe structure,&uot; said John Parker of Natchez, who was terminated in April as contractor on the dam and has worked on several other dam projects in the past. &uot;But (the NRCS) has cut corners, and when you add it up, it presents a dangerous situation.&uot;
An official of the Natural Resources Conservation Service, however, denied the charges and said the agency will bring engineers in no later than early March to review soil conditions and verify the structure is safe.
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NRCS and DEQ officials will then meet to discuss the findings and decide what actions to take, said the NRCS’ Kim Harris.
The agency’s actions follow a study commissioned by the state Department of Environmental Quality and finished in December on the project, a 1,051-acre recreational lake being built by the NRCS near Bude in Franklin County. Following an October site visit, Schnabel Engineering drafted a study recommending repairs of joints and cracks in the conduit, soil borings of the foundation and monitoring the structure to spot any future movement.
Next, the NRCS is expected to respond in writing to the DEQ’s concerns.
How important is the dam’s integrity?
The DEQ’s Jamie Crawford noted that, as the second-highest dam in the state, &uot;it’s qualified as a high hazard dam, meaning there could be loss of life (if it broke). Š There’s going to be a lot of water stored behind that thing.&uot;
An emergency action plan by the U.S. Department of Agriculture states that, in case of dam failure, morgue facilities should be supplied for up to five people and first-aid facilities for up to 75 people.
Such failure, the plan stated, could close bridges as far south as the U.S. 61 bridge north of Doloroso.
But Harris disputes that lives are at stake and said the NRCS is working to reassure Franklin County residents and the DEQ &uot;that we understand dam safety is an issue that is a top priority.
&uot;And, as we’ve always done in the past, NRCS will make both those entities sure the dam will be constructed safely and properly and will last for many years to come.&uot;
But Parker has compiled a file more than four inches thick on the project, including NRCS documents and correspondence between him and the agency and detail concerns regarding the project, including the soil on which it sits.
Documenting the dispute
As far back as March 1998, project engineers noted the dam’s design would have to be revised as excavation uncovered the extent of soft soil.
The NRCS’ project plan noted that &uot;excavation Š will require continuous inspection&uot; and that a regional soil mechanics engineers should be invited for inspections.
That wasn’t done, Harris said, &uot;because we had Š what we determined to be good foundation material,&uot; although a geologist was later brought it to review the project. The agency also noted in its reports that dispersive clay was found in foundation soils and a &uot;higher than normal Š settlement is estimated.&uot;
In February 2001 memos to the agency, Parker said four more feet of
soft soil should be removed. But the agency indicated later that month that the contract &uot;did not provide for payment for more than 12 inches&uot; of soil to be removed.
Parker hired an engineer, Clyde Pritchard of Starkville, to analyze the project, with Pritchard noting the agency had said the soil should be compacted 100 percent. The soil was actually compacted at 95 percent, which Pritchard said significantly lowered safety factors.
Harris said the agency decided 95 percent compaction was completely safe, especially since the soil under the dam would be compacted as construction went on.
After expressing concern about soft soil, Parker told NRCS officials the design of concrete blocks placed along the side of the dam was faulty, allowing water to channel into the sandy soil. In a subsequent letter, the DEQ also expressed concerns with the blocks and suggested its own changes. The agency has said Parker did not lay the blocks properly. Although a change order was issued for that part of the project in February 2003, Parker said the agency took 115 days to make its decision, during which time he could work on the project.
The agency wrote back that there were only 48 days when Parker couldn’t work due to weather conditions.
In April 2003, the NRCS terminated Parker’s contract for default &uot;due to failure to perform.&uot;
Lawsuit in works?
Declaring default &uot;is the worst thing you can do to a contractor, Š placing them in default,&uot; Parker said. Parker said he plans to sue in federal court to get a &uot;termination of convenience&uot; for the contract.
In a March 2003 letter to NRCS, Parker said he found settlement of the spillway, cracks and water leaks in the conduit and deformed dowels. Due to Parker’s concerns, the DEQ contracted with Schnabel to evaluate the safety concerns. Among Schnabel’s findings:
Two of the conduit’s joints have &uot;significant separation,&uot; and another &uot;had also settled differentially,&uot; causing the breaking away of concrete and the exposing of dowels and waterstop material.
The engineers said settlement may be continuing and could be made worse by the weight of water to be added to the reservoir.
Harris said the settling that has already taken place is very close to that predicted by the NRCS &045; a little more than 1.2 feet, compared to a predicted 1.3 feet &045; and repairing the joints due to that settlement was already in the agency’s plans several years ago.
Hairline cracks in the conduit appear to be minor but should be grouted and monitored. The cracks, Harris said, will be repaired with epoxy cement.
Borings should be made into the foundation to determine the presence of soft soil beneath the conduit and the potential for future settlement.
But the NRCS won’t bore the soil because other studies show it could weaken the dam, Harris said. If engineers arriving later this month or in early March determine it’s necessary, a penetration test could be done with a steel rod to determine soil resistance. If soft soil is found in the foundation, the agency will continue to monitor settlement &uot;to see what the outcome is,&uot; Harris said.
DEQ Director Charles Chisholm said Thursday the state will not require a new type of dam face or soil borings at the dam, but depending instead on &uot;extraordinary monitoring&uot; to make sure the dam is safe, the Associated Press reported.
The joints and reservoir drainpipe should be inspected, and joints should be repaired in a way that will allow for future movement. But Harris said the conduit was inspected Jan. 29, &uot;and the survey indicated that the movement has virtually subsided.&uot;
The conduit should be monitored for additional movement during and after completion and filling of the reservoir. &uot;The NRCS and DEQ are in agreement that the dam safety issues are of the utmost importance, and we are both working together to resolve these issues,&uot; Harris said. &uot;We will inform DEQ as to what measures we will take to insure dam safety.&uot;
Crawford said this week he is confident the NRCS will work in good faith to address safety concerns. Starting in March, contractor Pickett Industries, which has a $2.2 million contract, will begin smoothing the dam’s slope and reinstalling concrete blocks to help shore up the slope, and eight feet of fill will be added to the dam. The project should be finished late this year.