Clean water, dirty waste

The desal plant has been dumping too much cleaning fluid into sewer lines.

By Craig Pittman, Times Staff Writer
Published March 1, 2008

Over the past four months, Tampa Bay Water's desalination plant has been hit with three notices of violations of its wastewater dumping permit by Hillsborough County officials.

The most recent notice went out this week. Tampa Bay Water officials say they're hard at work to make sure there isn't a fourth violation.

The $158-million plant in Apollo Beach uses membranes to filter the salt out of seawater taken from Tampa Bay and turn it into drinking water.

The problem is, the membranes have to be cleaned periodically. Then the used cleaning solution, full of chloride, sodium and sulfate, is dumped into the sewer line.

To make sure the sewer plant doesn't get overwhelmed, Hillsborough County put a limit on how much of that stuff can be flushed into its sewer line, and how fast.

But in August, November and January, the plant flushed waste down the line that exceeded the gallons-per-minute limits, county officials say. The first time it happened was Aug. 24 and 25. The second was for a month, Nov. 2 through Nov. 28. And the third time was Jan. 29, 30 and 31.

One of those violations, the one for November, also included a violation for failing to promptly notify Hillsborough officials of the discharge.

The amount of cleaning fluid waste wasn't enough to harm the county's sewer plant, said London Womack of the county's water resources services department. But it was more than the desal plant's permit allowed.

Although the county has threatened to fine the plant, so far it has not done so. Tampa Bay Water operations manager Chuck Carden said the utility's plant operator, American Water Pridesa, is working to fix the problem.

The system that flushes out the cleaning solution is one of the last manually operated systems in the desal plant, which after failing a crucial test in 2003 underwent a lengthy repair process. It finally reopened in January, more than four years late and costing $40-million more than expected.

Carden said all the violations occurred during the repairs, and he blamed operator error and a faulty flow meter for both the discharge problems and the failure to notify Hillsborough County. He said plans are being formulated to switch to an automated system that will be more reliable.

During the switchover, the plant will have to pour the used cleaning solution into tanker trucks and drive its waste to the sewer plant, he said.

The cleaning solution has caused Tampa Bay Water problems before. Four years ago, prior to the repairs, the plant's filters clogged so frequently they needed cleaning more often than expected and with a stronger solution.

When Tampa Bay Water changed and increased the cleaning solution for the membranes, Hillsborough County balked at allowing large quantities of the cleaning solution to be disposed of in its sewer system. So the company that was then operating the plant, Covanta, was forced to store 2-million gallons in tank trucks that remained parked around the site until they could be emptied.