THIS STORY HAS BEEN CORRECTED. See below.

The city has broken ground on a second digester at the Sand Island Wastewater Treatment Plant that Mayor Kirk Caldwell and other supporters say is necessary to expand the city’s sewage capacity and clear the way for more housing on Oahu.

Like the existing egglike 100-foot tall digester, the second facility will use bioconversion to transform sewage sludge into fertilizer pellets, which can then be used by agricultural operations, or at least take up less space in the city landfill.

"We’re on the cusp of a major construction boom — much-needed housing that hasn’t happened since 2008 … and we don’t want to hold back on these projects if at all possible," Caldwell told the Honolulu Star-Advertiser on Tuesday.

Scheduled to be completed by mid-2016, the $29.1 million project has met with resistance from key members of the Honolulu City Council who think the city should be holding out for better and more efficient technology.

In June skeptical Council members refused to provide Caldwell’s administration with the $6.2 million it requested to pay the remaining tab for the second digester in this year’s budget, instead agreeing to fund only $1.5 million of it.

But Markus Owens, spokesman for the city Department of Environmental Services, said the reduced funding will not have an impact on the project’s timetable because the city is working with the contractor, Synagro Hawaii, "to fast-track the project and contain costs."

Owens said, however, time delays — due to a Council resolution requiring the city administration to look at alternative technologies and a request to have the state Procurement Office look at the propriety of the city’s contract with Synagro — raised the project’s costs by about $3 million from its original $26 million by resulting in higher costs of materials.

Caldwell told the Star-Advertiser that a second digester is a no-brainer. Groundbreaking was Thursday.

"With the building of a second digester, we add capacity and, in some ways even more importantly, redundancy so if we ever had a problem with the first egg, we could still continue to process sewage," Caldwell said. About 60 percent of sewage generated on Oahu — from Kuliouou to Red Hill — is serviced by the Sand Island treatment plant.

Many major projects planned for Kakaako, including developments by Alexander &Baldwin, the Howard Hughes Corp. and One Ala Moana, already have the full OK for sewer hookups, city officials said. But others, including numerous projects in Waikiki and the transit-oriented development proposals being eyed around the hubs of the city’s $5.26 billion rail line, do not, Caldwell said.

"Timing is really important," Caldwell said, "because with lower interest rates, with the demand and where the market is, these projects go forward. But this window does close at some point, which could drastically impact development in our urban core."

Kalihi-area Councilman Joey Manahan said that he, like Caldwell, is being a pragmatist on the issue. "We need the added capacity to be able to accommodate the growth of our city," he said. Additionally, the first digester is long overdue for major maintenance work, and a second digester needs to be in place to handle the capacity before that can happen, Manahan said.

Manahan’s comments are a departure from the strong anti-digester position of his predecessor, now state Rep. Romy Cachola. Cachola fought against the first digester when it was first proposed by Mayor Jeremy Harris more than a decade ago.

Later he cited public health and safety, impacts on area businesses and residents, marketability of fertilizer pellets, visual blight and cost overruns involved with the building of the initial digester as some of his reasons for opposing a second digester.

Cachola subsequently led the fight against both digesters as proposed by Mayors Mufi Hannemann and Peter Carlisle. He was the lead author of a resolution requiring the city fully examine alternate means of dealing with the sludge before it could spend the initial $21.5 million. A report by a paid third-party consultant concluded that "there may be both conventional and emerging technologies that may be of benefit" to the city, but did not conclude it should nix a second digester. The Council ultimately let the money be used.

In May 2012 Cachola asked the state Procurement Office to look into the propriety of the city’s decision to "expand" its Synagro contract rather than go through the traditional contracting process. The procurement ruled in September 2012 that the city acted properly.

Though Cachola left Honolulu Hale in 2012, other skeptics remain, including Council Chairman Ernie Martin and Council Budget Chairwoman Ann Kobayashi.

Martin said he agrees with Caldwell’s reasoning behind needing to expand capacity at the Sand Island plant. "My reservations are focused more on the type of technology," he said.

Other companies have approached the city with more efficient technologies that would not require the disposal of pellets that would further tax the city’s solid waste disposal facilities.

"I would hope the city would take a step back and consider some of the more cutting-edge technology that can generate electricity while still processing the waste through the facility," the Council chairman said.

Kobayashi said she also believes the city should look at companies that have told the city they can generate electricity with sludge.

Both Martin and Kobayashi also said Council members were told when city officials first chose Synagro’s digester technology more than a decade ago that the sale of the pelletized fertilizer that was the byproduct of the system would be able to pay for the system.

"They told us it would be self-sustaining,"Kobayashi said.

But Owens, the longtime Environmental Services spokesman, said, "We have always stated to the City Council that pelletized fertilizer is not meant to make money."

Acknowledging that little money has been generated, Owens said that 93 percent of the pellets have been distributed to local markets and used at city parks and golf courses, with the remainder disposed of in the landfill and HPOWER.

CORRECTION: The groundbreaking for a second digester at the Sand Island Wastewater Treatment Plant was Thursday. An earlier version of this online story and a story on page A1 of Wednesday’s paper said the groundbreaking was Friday.