ANTIOCH -- Looking not to be left high and dry by an underperforming water treatment system upgrade, the city has sued the contractors that built and designed the new facility.

The dewatering system, or treatment that separates sludge from the water through filtration and dries the remaining solid product, has shown performance problems and defects because of misrepresentations and omission of information by Black & Veatch, F.D. Deskins Co. and Miscowater, according to the Jan. 28 suit filed in Contra Costa Superior Court.

The multimillion dollar suit says Black &Veatch, hired in 2004 to design a water treatment plant expansion, recommended use of a system provided by Deskins, but miscalculated the amount of dry solids generated by the plant by almost 33 percent, accounting for an average of 11,500 pounds per day instead of the actual average of 15,209 pounds.

Installed sand drying beds are unable to drain 487,610 gallons of sludge in one bed in one day.

Black & Veatch did not perform any pilot study or bench test to confirm it could process the quantities of sludge promised in the December 2005 proposal or if the system had been installed at a treatment plant that used the same aluminum-based chemicals as Antioch's, according to the suit.

"After much time and effort trying the resolve the problem with the involved parties to no avail, (Antioch) has been forced to file a lawsuit to recover its damages because the upgrades simply do not work," City Attorney Lynn Tracy Nerland wrote in an email to this newspaper.

Antioch is seeking damages for the purchase of the system, the construction of infrastructure, the cure for the system so it works properly, or a replacement, and the cost to hire experts to analyze the system's problems, and legal costs.

It remains uncertain how much the city is seeking. However, each drying bed cost about $490,000 and Antioch's system had four installed.

Black & Veatch spokesman Patrick MacElroy responded to an inquiry about the complaint in an email, saying: "The issues raised in the litigation relates to the performance of the dewatering system, which was provided and guaranteed by a supplier under direct contract with the city. Since this matter is in litigation, it is our policy to not publicly discuss further details."

Kerry Shea, the attorney representing Deskins, said the system works and that it's "unfortunate" the city cannot work out its issues with its engineers and that it is spending so much in legal costs. The Deskins company tried to assist, she said.

"We hope the city and its engineer can work this out," Shea said.

Representatives with Miscowater did not return phone calls seeking comment.

Antioch water customers should know that the problem relates only to waste treatment, and that the quality of the city's potable water remains high, Nerland said.

Contact Paul Burgarino at 925-779-7164. Follow him at Twitter.com/paulburgarino.