Awaiting repair STAFF PHOTO BY DAN PARKER Some of the rocky revetment at the Port Aransas Nature Preserve at Charlie’s Pasture has slumped toward the Corpus Christi Ship Channel, exposing black sheets of fabric that normally serve as underlying parts of the structure. The revetment is being undercut by erosion, and engineers are surveying the scene to determine what to do about the problem. Engineers are surveying the rocky revetment along the shore at the Port Aransas Nature Preserve at Charlie’s Pasture because city officials are concerned that it is slumping and in need of repair.

About 4,500 feet of revetment was installed in 2007 to protect the shoreline against erosion. The revetment, composed largely of limestone rocks, stretches from a section of concrete bulkheads to Piper Channel.

The $2.5 million cost was funded by grants from the National Oceanic and Atmospheric Administration and the Texas General Land Office.

Portions of the revetment are being undercut by erosion, and sections of rock are shifting away from shore, said Dave Parsons, the planning and projects director for the city.

Thirty to 40 percent of an 800-foot section of the revetment is slumping downward, exposing black sheets of fabric that normally are an underlying part of the structure, Parsons said.

In front of the revetment, water that was only three feet deep in 2007 is now five to six feet deep, Parsons said. It’s being caused by erosion from water movement in the channel, both from ship traffic and tidal influences, Parsons said.

The revetment was installed because up to 15 feet each year was being lost due to water movement.

The project’s design engineer was Shiner-Moseley of Corpus Christi. Engineers from the firm, now known as HDR/Shiner-Moseley, have been surveying the revetment for the past few weeks to determine what has happened, whether more slumping is continuing to take place, how fast it’s happening and where else it could take place, Parsons said. Engineers also will propose what should be done in response to the situation, Parsons said.

“We are working very closely with the city of Port Aransas on the shoreline revetment and consider it a routine maintenance item,” said Jackie Fox, media relations manager at HDR’s corporate office in Omaha, Neb.

“Routine maintenance was anticipated due to frequent surge from passing ships and possibly aggravated by effects of Hurricane Ike,” Fox said. “We are working with the city to see if there is any FEMA funding available due to Hurricane Ike, and whether there might be state funding available as well.”

Parsons said it’s hard to tell how much repairs could cost, but he estimated it could be $200,000 to $300,000.

Engineers will do some more surveys in a few months to see what changes, if any, are taking place, Parsons said.

The city asked the engineering firm to check out the revetment after city hall got calls from observers who said the contour of the revetment looked like it had changed.

The GLO actually owns the revetment, but the city is involved because construction of the structure was a partnership between the city and the GLO. It was the city that won the NOAA grant that partially funded the revetment construction.