On Dec. 6, Austin City Council approved a $15.5 million increase to the budget for Water Treatment Plant 4 to accommodate the remaining construction.

The increase brings the project cost to $524 million, up from $508 million, for the construction, design, land purchase, easement and permitting process. Austin Water Director Greg 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.

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.

Meszaros said the remaining projects include construction of the backwash pump station that will aid in cleaning the backwash filters and, on rare occasions, pump water into the system.

Throughout 2013 and into 2014, Meszaros said construction will continue on the 7-mile Jollyville transmission line that runs at a depth of 100 feet or more underground from the treatment plant to McNeil Drive and Research Boulevard, where it connects to the Jollyville water tank and distributes water into the utility's system. He said crews are now more than 50 feet underground and residents should not hear or see much activity.