When Sacramento County officials said two years ago that they would have to spend more than $2 billion to meet more stringent environmental requirements to treat wastewater, state regulators responded that the cost was much less.
Now, the county has essentially agreed, and sewer rates should be much lower than expected.
The Sacramento Regional County Sanitation District, which provides service to 400,000 customers in Sacramento County and West Sacramento, released cost estimates for treatment improvements this month that are as much as 48 percent lower than the original estimate.
For homeowners, the average monthly sewer bill is expected to rise from $24 to $45 or $46 in seven years. Previously, the district expected the monthly rate to rise to $68. (Those figures do not include separate costs added by local agencies.)
District board members expressed qualified relief about the lowered estimates.
"I don't know how good we should feel about this," said Don Nottoli, a Sacramento County supervisor. "It's the difference between the doubling and tripling of rates, but at least it's going in the right direction."
While the costs aren't finalized, the district's updated plans are expected to save hundreds of millions of dollars over earlier plans. The money will pay for treatment technology at the district's wastewater treatment plant near Elk Grove.
The improvements are needed to meet the requirements of a wastewater discharge permit issued by the Central Valley Regional Water Quality Control Board in December 2010.
The requirements, regulators say, are necessary to protect the Sacramento River from pollution that hurts people and aquatic life as far as 30 miles downstream from discharge released near the Freeport Bridge.
The district has already started raising rates to pay for the improvements, and those raises will continue, although not as much as originally planned. District staff will ask the board, made up of elected officials in the region, to raise rates again sometime next year.
The district was able to lower cost estimates for the upgrades because of a pilot project that tested treatment options in three locations, said Prabhakar Somavarapu, director of policy and planning for the district.
The permit required the district to do three things, he said: remove ammonia, put in filtration and put in a higher level of disinfection. They can be done in quite a few different ways.
The pilot project tested different options and revealed, for instance, that using sand for filtration instead of synthetic membrane costs hundreds of millions of dollars less and is still effective, Somavarapu said.
The pilot project, paid for by the district's initial rate increases, was conducted over 12 months through April 2012 at a cost of $18 million.
It confirmed the expectations of the Central Valley Regional Water Quality Control Board, said Ken Landau, assistant executive officer at the board.
"We felt they were being overly conservative and offering the worst-case scenario," he said.
The original estimate, which the district used while fighting the permit requirements, was completed by a nationally renowned consultant it hired, Carollo Engineers.
The state board, in turn, hired its own consulting firm, PG Environmental, to review the Carollo estimate. The review determined that the district's cost was likely to be 35 percent lower than Carollo had projected.
The district's estimates were also higher than what was spent to make the same improvements at wastewater plants in Tracy, Lodi, Stockton and Manteca, said Landau.
Pat Hume, an Elk Grove City Council member, said he and other directors on the sanitation district board will continue to press for cost reductions. The board's staff expects to continue to make revisions before the project goes out to bid. The improvements must be finished by December 2021, when the permit requirements go into effect.
"The savings if realized are significant, but this is still a very big expense," Hume said.
Reggie Jardon, an Elk Grove retiree and ratepayer, agreed.
"For people on a fixed income, this is going to be a lot of money," he said. "Any significant raise and I would call this significant is going to hurt."