The Water Treatment Plant 4 project received about $15.5 million in additional funding Dec. 6 with Austin City Council's unanimous approval.

The initial total cost of the project was about $508 million, with about $359 million allocated for construction. The additional funding approved by council brings the construction contract up to $374 million and the total cost of the project to about $524 million.

Jason Hill, spokesman for Austin Water Utility, said the additional $15.5 million will be built into the utility's debt service bonds.

One of the concerns expressed by council regarded the flexibility of $359 million budgeted for the project. According to council members, many thought the $359 million was a maximum guaranteed price, rather than just an estimate for the construction costs.

"I think we played it just exactly the way we should have, except the council needed to know what the game was," Councilman Bill Spelman said during the meeting. "I did not know what the game was, I know at least a couple of us didn't, and I suspect most of us didn't."

Austin Mayor Lee Leffingwell said he understood from the outset that $359 million for construction costs was an estimated figure and that costs could change.

"I certainly never thought that the guaranteed maximum amount was $359 million," Leffingwell said. "The guaranteed maximum price part was to be based on several different projects, once the final engineering was complete. The $359 [million] was based on preliminary engineering estimates."

Most residents who signed up to speak to the council on the topic chimed in on the vein of "we told you so."

"We said there were going to be cost overruns," said Roy Waley, vice chairman of the Sierra Club Austin Regional Group, who spoke during public comment on the council item. "We said that there were going to be issues with this project that weren't being addressed."

The Austin Sierra Club is a volunteer organization that promotes environmental conservation and education.

The plant is located at the southwest corner of Bullick Hollow Road and RM 620, and 96 percent of the project is bid out and under construction. Greg Meszaros, director of Austin Water Utility, said the project includes 13 construction packages that are be bid out over a multiyear period. There are two remaining aspects of the project that have yet to be bid on, including construction of a backwash pump and final site work.

"As we bid out each package and award that work to our contractor, that particular portion of the contract is guaranteed, once it reaches that stage," Meszaros said.

The two remaining projects are expected to be bid on in 2013. Meszaros said once those contracts are bid, they will be guaranteed maximum-priced contracts.

City officials said some the additional costs for the project have been to address environmental and neighborhood concerns with the project, including tunneling the entire length of the Jollyville transmission line rather than just two-thirds of the line that was called for in the preliminary plan.

"This has been a project that has evolved over several years, and I remember saying at the time, that with a project of this scope, there could be changes as we went along." Leffingwell said.

Meszaros said though he thinks the construction contract including the increase is sufficient for the project, he stressed that there still could be unforeseen circumstances.

"I cannot, nor can anyone, guarantee that this project is not going to have another issue along the way," Meszaros said. "With everything we know today, we don't believe we're going to go over [budget], and our behavior has been very [good], but there are what they would call act of God things that no one can control."

Austin City Manager Marc Ott said despite the breakdown in communication about the project, he feels it is an essential step in providing services as the city continues to grow.

"At the end of the day, I think [the water treatment plant] is going to be successful, and I think it is absolutely necessary in terms of long-term viability of this city and our ability to provide adequate and high-quality water," Ott said.