Side-stream savings tiny, utility hears

Thursday, May 22, 2014

Eliminating the need to build extra storage facilities by using a side-stream treatment method likely won't lower construction costs enough to affect sewer-rate proposals, but it's still beneficial, an engineering firm told the Little Rock Sanitary Sewer Committee on Wednesday.

Previously, Little Rock Wastewater officials had hypothesized that getting approval from state and federal regulatory agencies to use the side-stream method and to no longer build two planned storage facilities would be cheaper and result in lower rate-increase proposals.

The utility plans to request approval for a series of rate increases from the Little Rock Board of Directors in November but hasn't settled on the exact amounts.

Last year, the utility's then-chief executive officer announced the rate-increase package, but after he was fired in January, staff members decided to revisit the proposals. They plan to hire a consultant and will make updated recommendations to the Sanitary Sewer Committee later this year.

The new proposals will likely not be the same as what was previously announced, interim CEO of Administration and Finance John Jarratt said. He added that there are other opportunities -- aside from implementing side-streaming -- that officials have been researching as a possibility to lower the rate-increase amounts.

Though side-streaming isn't the answer to reining in rate increases, it's still beneficial and favored over building extra storage, representatives from Hawkins-Weir Engineers Inc. said.

The method has only recently become an option for Little Rock Wastewater after the 8th U.S. Circuit Court of Appeals ruled in March against the federal Environmental Protection Agency's restriction of side-streaming. The EPA had been curbing its use after permitting it in the past. The court ruled that the agency had in effect created a new rule and didn't follow the proper procedures under law to do so, thus striking down the EPA's rule.

A group of Iowa cities had sued the agency, saying that prohibiting side-streaming would cause them to have to build costly storage facilities to mitigate overflows and handle sewage treatment during peak times when rainfall enters the sewer system and overburdens a treatment facility.

The EPA estimated that its requirement would have cost cities across the nation $150 billion collectively to build new storage facilities that could handle high inflow during rainstorms.

The 8th Circuit's ruling only applies to states in its jurisdiction -- Iowa, Minnesota, Missouri, Nebraska, North Dakota, South Dakota and Arkansas.

The EPA hasn't filed an appeal but has said the ruling does not vacate a rule in the Clean Water Act on bypassing steps in the treatment of sewage when it rains. No treatment plant has been issued a permit to use the side-stream method since the court's decision, and it is unknown whether the agency would approve a proposal to use the method in lieu of additional storage.

Side-streaming is when a plant operator funnels extra flow into a treatment facility during heavy rain around the typical biological treatment process and into a nonbiological, side-stream treatment. The extra flow then is blended back in with the other sewage that was biologically treated, enters a disinfection stage and is released.

Implementing that method at the Little Rock Adams Field Wastewater Treatment Plant, along with adding some additional storage that will still be needed, is estimated to cost about $44.2 million. It would take the place of a $44.5 million project that called for the addition of an off-site 51 million-gallon storage basin and another on-site 14 million-gallon storage basin.

Employing the side-stream method would eliminate the need for the extra storage basin at the Adams Field plant -- a project estimated to cost $13.1 million -- and allow that land to be used for other improvements in the future. While it wouldn't eliminate the need for the 51 million-gallon storage facility at Scott Hamilton Drive, it would reduce it to a 31 million-gallon basin, said Aaron Benzing, principal of Hawkins-Weir Engineers Inc.

This is important because city directors and the community have expressed concerns about building that storage facility so close to the Geyer Springs neighborhood. Reducing the size of the basin will create a larger buffer between it and residential areas, which would likely result in a more favorable response from the public, Benzing said.

The primary benefit of side-streaming versus adding storage is its effect on overflows during heavy rains, Benzing said.

Now, once a certain amount of rainwater enters and a storage basin is full, the flow has to be cut off, resulting in overflows across the city during many storms. But with side-streaming, any inflow to the treatment plant that exceeds the plant's capacity can be side-streamed. Plant operators can side-stream overflow for the duration of the storm.

"Blending with side-stream treatment has been around since the '70s ... and is generally believed to be a cost-effective and good [method]," Benzing said. "A treatment plant is designed for the amount it gets in a typical day, not for peak flows."

The method also would improve plant operations by not stressing the biological agents used to treat sewage and allow for double use of the nonbiological treatment area during nonpeak times to help with disinfection.

Little Rock Wastewater is working on a proposal to submit to the Arkansas Department of Environmental Quality that would seek authorization to use side-streaming. The modification to the utility's plant permit would have to be approved by the EPA.

"There's no certainty with either of these agencies as we move forward," Hawkins-Weir President Fred Oswald said. "The permitting process is rarely simple and in this case it will not be simple."

Little Rock Wastewater's interim CEO of operations, Howell Anderson, told the sewer committee Wednesday that moving forward with side-streaming is "the right thing to do and something we've got to try."

A section on 05/22/2014