Published: October 16, 2007 10:07 am      

Rust to judgment

Corrosion found on dam gate takes it out of commission

By Libby Cluett
lcluett@mineralwellsindex.com

POSSUM KINGDOM LAKE – Post-flood inspections of the floodgates used during the summer release of 85 percent of PK’s water revealed that one gate had areas of corrosion and has subsequently been taken off the list of useable gates, while another gate also used in the operation is slated for rehabilitation and will be out of commission this year.

When opened, water moves through a gate at a rate of 10,000 cubic feet per second. After flooding operations, BRA conducts an inspection of the dam structure, according to Public Information Officer Judi Pierce. This includes inspectors examining the interior and exterior of the metal hollow-core floodgates that were used.

“The finding from the summer’s events was that one of our gates did show some corrosion – which is normal considering the salinity levels of the water at PK,” Pierce said.

This translates into small rusting areas that will eventually grow if untreated. According to Pierce, gate four will be taken off the list gates the authority can use during a flood until it is rehabilitated.

“This gate in particular has not yet received a special sealant coating to protect it against corrosion that we’ve routinely been applying to the dam gates we’ve rehabbed over the last several years. The plan is to put this gate out of commission for releases until the sealant can be applied,” Pierce added.

Pierce explained that when the authority first started replacing the gates in 1995, the sealant coating now being used was not available so the gates replaced first did not receive the coating.

BRA is in the midst of the multi-year project to rehabilitate all nine of the 66-year-old dam’s steel gates that help contain and manage water in PK Lake. More recently replaced gates received a zinc coating to protect them from corrosion.

“There is absolutely no threat to the integrity of the dam from the releases made this past summer. Otherwise, we are still working on the gate rehab program we began seven years ago. This project will be ongoing for many years,” said Pierce.

In addition to gate four, four others are out of commission for varying states of rehabilitation, leaving the dam with four available gates for flood control.

Constant spring and summer rains – locally and in West Texas – led to the release of 85 percent of PK’s water and the historic opening of four Morris Sheppard Dam gates at Possum Kingdom Lake in late June and early July.

Between June 24 and July 6, PK Lake became a river again. During this period, the Brazos River Authority had from one to four gates opened and, according to authorities, released a total of 445,000 acre feet of the lake’s 533,690 acre feet capacity.

Further down the river, floodwaters took their toll on the land. Last week Litchfield and Sons of Tolar, Texas, started cleaning up debris that floated into Lake Granbury.

“We’re pleased to have the process in place to begin cleanup of portions of the lake,” said Kent Rindy, BRA Upper Basin Regional Manager. “Based upon available funds, we’ve identified specific areas that we believe have the greatest need for debris removal out of concern for the public health, safety and welfare as it relates to those particular areas.”

BRA hired the Litchfield and Sons for $98,000 for the project after receiving sealed-bids. Pierce said they are trying to see if BRA can work with the Federal Emergency Management Administration for aid with the Granbury cleanup.

Unlike past floods, which swept trees, logs and other organic material into the lake, this season’s flood presented items such as propane tanks, docks, tires, sunken boats, Styrofoam, storage sheds and refrigerators, according to Pierce. These items preset a safety hazard for boats.

The debris is being removed by barge and transported to four designated areas for disposal

“This is the first time in the history of BRA that we have had to do this [type of cleanup],” she said, adding, “People are building much more often in flood areas.”