A company drilling a natural gas pipeline route under Tampa Bay this summer spilled a chemical that has killed about 2 acres of sea grass, according to the state Department of Environmental Protection.
"We are investigating the sea grass die-off," DEP spokeswoman Pamala Vazquez said Monday.
The spill by Gulfstream Pipeline killed sea grass beds about 1,500 feet due east of the Progress Energy power plant on Weedon Island, she said. Investigators have snorkeled through that area of the bay several times, including last week trying to chart the extent of the die-off.
Earlier this month, the company finished removing the chemical that leaked, said Gulfstream spokesman Christopher Stockton. The company's experts say the sea grass die-off may not be as extensive as the DEP fears.
Six years ago, Gulfstream built a $1.6-billion pipeline that stretched for more than 400 miles under the Gulf of Mexico to carry natural gas from Mississippi and Alabama to Port Manatee, just south of the Sunshine Skyway bridge. It then ran about 300 miles of pipeline overland to power plants throughout Central Florida.
Then Progress Energy announced plans to modify its Pinellas County plant to double its generating capacity and switch it from burning fuel oil to cleaner-burning natural gas. In January Gulfstream began digging a 17-mile branch from the Manatee County end of its pipeline to connect to the refurbished plant. Work on the new 20-inch diameter pipeline wrapped up this week, Stockton said.
Gulfstream used a technique called horizontal direct drilling, cutting its hole for the pipeline a minimum of 3 feet down from the bay's bottom. To lubricate the drill, the company uses a chemical called bentonite, which is made from volcanic ash.
On June 25, the bentonite broke out of the hole being drilled, Vazquez said.The company notified the DEP within 30 minutes, but the damage was done.
The bentonite that leaked into the bay did not poison the sea grass, she said, but slowly smothered it by blocking off sunlight that it needs to live.