The Austin City Council is scheduled to vote Dec. 6 on whether to increase the budget for the Water Treatment Plant 4 project by $15.5 million.

Austin Water Utility Director Greg Meszaros said 96 percent of the project has been bid and is under construction, with many of the components nearing completion. The plant, located at the southwest corner of Bullick Hollow Road and RM 620, will be able to treat 50 million gallons of water per day when it opens in summer 2014.

The initial total project cost was $508 million for the construction, design, land purchase, easement and permitting process, with $359 million allocated just for construction. Meszaros said the final 4 percent of the project and the contingencies for unexpected costs are carrying the project over budget. However, he said the final project cost could be between $506 million and $512 million.

"We still may be at our total budget or slightly above," he said, because the city may not need to use all the contingencies or allowance budgets.

One of the final two aspects of the project is to construct a backwash pump station that will aid in cleaning the backwash filters and, on rare occasions, pump water into the system.

Meszaros said that normally the system will use the flow of gravity to distribute water into the system but occasionally the aid of a pump will be needed. This component will cost about $9.5 million; the contract for the work will be awarded in 2013.

The remainder of the money will help finish out the site by paving the roads at the treatment plant, back-filling dirt and getting the occupancy permit, he said.

During the city's Nov. 19 Audit and Finance Committee meeting, council members expressed concern that they did not know when the project was approved, and that the $359 million budgeted just for the construction was not capped.

"One of disturbing things for me is when I voted for that contract, I thought that was the number," committee Chairwoman Sheryl Cole said. "I thought that as you built contingencies and allowances and value engineering, I thought that would all work out and eventually be that number or below."

Meszaros said that with any project, staff completes what is called value engineering to determine how to achieve project goals at a lower cost.

The total project includes 13 individual packages, each with its own budget. He said that some of the packages went over budget—such as the raw water system that cost $14.6 million more than estimated—while other packages came in under budget.

Council member Laura Morrison said that there has been a lot of confusion with budget numbers since the beginning of the project and that being off budget is not acceptable.

"It seems like a pretty bad guesstimate record," she said.

At the meeting, city audit staff said Austin Water Utility already made $24 million in cuts and deferred $20 million worth of projects.

One of the deferred projects was the construction of a secondary water transmission line that would carry water for distribution to Austin Water's system. Meszaros said the decision to defer the work came after the utility decided to fully bury the 7-mile Jollyville transmission line that will run from the plant to the Jollyville water tank at McNeil Drive and Research Boulevard.

"The risk of Jollyville having a problem, like a contractor hitting it, is virtually zero now," he said.

Meszaros said Austin Water Utility cannot complete the project without council authorizing the additional $15.5 million.

"In my opinion, we have taken all the appropriate steps that we can ... and additional steps would result in a plant that did not meet its original design goals," he said at the Nov. 19 meeting. "We would endanger, potentially, the environment by making cuts that reduced our flexibility to respond to environmental concerns. We would have a project that would not work."