NATCHEZ — What board of supervisors attorney Bobby Cox thought was just a friendly wave was actually a warning he now wishes he had heeded.

Returning to his office after lunch Monday, Cox made his usual right hand turn from Canal Street to Franklin Street, but this time his truck came to rest in a sinkhole as a portion of Franklin Street collapsed.

“I’ve made that turn 10 to 15 times a day for 35 or 40 years,” Cox said.

Cox said a motorist in front of him hit the damaged area but did not break through the asphalt.

“His tire went off in it, but he was able to drive through it,” Cox said. “When I started to make the turn, he ran out and tried to flag me down.

“I just waved at him, and boom.”

Cox said he was traveling 10 to 12 miles per hour when he hit the sinkhole.

“I came to an instant stop, and luckily I was belted in,” Cox said. “It snapped my head forward, but I’m OK.

“I put the truck in four-wheel drive and it wouldn’t do anything.”

Natchez City Engineer David Gardner said the cause of the road collapse was the presence of a large cavity under the road.

Gardner said the cavity was likely formed years ago by the same water source that damaged a 200-year-old canal that runs under Canal Street.

Repair work on the canal was done in 2007, but the cavity wasn’t discovered until Monday.

Gardner said as water seeps into the ground it flows downhill, taking dirt and soil with it. He believes years of that, left the cavity.

“When we did that other work, we didn’t find this cavity,” Gardner said. “We are an old town, and we don’t know where they all are.”

The cavity is approximately 20-feet long and 8- to 10- feet deep at its deepest point.

Gardner said in the cavity was a gas line, a water line, a sewer line, an abandoned gas line, a storm drain, two traffic cables and old rail road cross ties.

But he said crews were able to determine that none of the utility lines were the cause of collapse and none of the lines were damaged in the collapse.

“If it was the sewer line it would have been wet and the same thing with the water line and storm drain, and if it had been the gas line we would have all smelled gas,” Gardner said. “It was dry as a bone down there.”

The intersection was closed after the collapse and will remain closed until repairs can be made. Gardner estimated repairs would take two to three days.

Natchez Water Works and the public works department will work together on the repairs.

Gardner said crews will use an encapsulated sand blanket to fill the cavity and support the road.

“We will lay down a layer of fabric then fill the cavity with sand and wrap the fabric over the sand,” Gardner said. “What that will allow is for the water to flow through the sand without taking anything with it and creating another cavity.”

On top of the sand blanket, eight inches of gravel will be put down and topped with four inches of asphalt.

Gardner said it is hard to predict where other cavities might be, but said indentions in the asphalt can be the first indicator of a cavity’s presence.

Cox said a small cut on his wrist caused by his watchband is so far the only evidence of the mishap.

“I guess that is a well built truck,” Cox said. “After they pulled it out of the hole it cranked right up and the air conditioner worked and it drove just fine.

“It’s just one of those things that you think ‘how did this happen to me.’ I’m sorry it happened, but at least I was in a big heavy truck and belted in so I didn’t get hurt.”