Beginning next month, the Honouliuli Wastewater Treatment Plant in Ewa will receive additional truckloads of raw sewage sludge from Sand Island as the city begins testing for a long-term plan of hauling waste to reduce intake at the over-capacity Honolulu site.

The city ultimately plans to haul the sludge to plants in Kailua and Waianae — in addition to Honouliuli — as it deals with delays in the expansion of facilities at Sand Island, which takes in sewage within the urban core from Aina Haina to Halawa. Test runs are not being made to Kailua and Waianae at this time because of mechanical issues at those plants, officials said.

Mayor Peter Carlisle has ordered a formal environmental assessment be conducted on the plan to haul sewage to all three waste-water treatment plants.

"Since it may be inevitable, it would be a waste of time to wait until we are ordered to do it," Carlisle said in announcing the hauling plans at a news conference Wednesday. "Therefore, we will do it now."

Hauling sewage sludge to the other plants is seen as a temporary means of relieving the over-capacity "digester" at Sand Island while the administration and City Council work out plans for the safest, most cost-effective way to expand the facility.

"I do look forward to working with the administration to finding a long-term solution and I think the Council is committed to that end," said City Councilman Ikaika Anderson.

Anderson, whose district includes Kailua, said he is pleased with the decision to conduct an environmental assessment. Reaction from lawmakers in affected communities was mixed, as some appreciated the environmental study but remained wary of sludge being trucked through residential areas.

"The fact that they’re doing an environmental assessment, at the very least, is commendable and certainly should be done," said state Sen. Will Espero, whose district includes the Honouliuli plant where about 111,600 gallons of sludge is trucked per week. "We’ll see what comes of that. It’s just unfortunate that this whole situation has gotten to this point."

Councilman Tom Berg, whose district includes the Honouliuli and Waianae plants, was among those more critical not only of the trucking, but also of current and former mayoral administrations for what he called the prioritizing of the proposed $5.3 billion rail transit project ahead of dealing with aging sewers and other infrastructure needs.

"Everyone in District 1 that is upset with sludge being shipped to their backyard and being in receipt of the island’s woes, needs to re-evaluate the pursuit of rail that is killing our quality of life even before the rail has even begun," Berg, a vocal rail opponent, said in an email statement. "It’s that simple — fund sewers or rail, and the voters want rail, and this is the result.

"Now we have to live with it — a misdirection of priorities sold to us by a previous adminstration, or raise taxes to flush in confidence."

Carlisle said the test runs could not immediately be made to Waianae because that plant’s digester remains full of silt from flooding in January, or to Kailua, where the plant is in the midst of upgrades.

Rep. Cynthia Thielen, who was among the first to raise the prospects of a formal environmental assessment, said she is pleased with the steps the city is taking and she expects the assessment to back her contention that added sludge at the Kailua plant would affect students at nearby Aikahi Elementary School.

"I believe that the assessment will show there would be a significant impact on the elementary school students who go to school right next to the sewage facility and on neighboring residents," she said, noting that over the years students have been sickened and sent home because of odor from the plant.

"You can’t be trucking raw sewage and disgorging it into the plant without additional odor problems," she said.

Test runs will involve no more than one 5,000-gallon tanker a day on intermittent days for no more than 30 days, and the city will use "all available means," Carlisle said, to reduce odor. A hotline for reporting problems also will be set up.

The city will evaluate effects at both Honouliuli and Sand Island, Carlisle said, noting that wastewater takes 28 days to go through the treatment process.

"Once we have that analysis, what happens will depend on what we learn," Carlisle said. "We may begin testing the feasibility of Waianae and Kailua treatment plants or we may do further capacity testing at Honouliuli."

Carlisle said he does not know how long the existing digester at Sand Island could operate without the diversion, but expects test runs to give officials a better idea.

Without it, Carlisle said the city would have to impose a moratorium on new sewer hookups in the urban Honolulu area, possibly stifling construction projects and economic growth.