Officials with Mayor Kirk Caldwell’s administration told the City Council Public Works, Infrastructure and Sustainability Committee on Wednesday that they will look at ways of expanding sewer capacity on Oahu in response to concerns that applicants for accessory dwelling units are being turned away because of the limitation.

The committee advanced Resolution 17-193, which calls on the administration to speed up expansion of Oahu’s sewer system. Committee Chairwoman Carol Fukunaga added language asking that city officials provide an update on the situation within 90 days of the resolution being adopted.

City officials told the Hono­lulu Star-Advertiser last week, and then reiterated Wednesday, that 344 preliminary applications were rejected because sewer capacity in their neighborhoods was inadequate to add new dwellings.

ADUs are “second dwellings” on residential lots that are approved outside the city’s standard building and land use regulations. Mayor Kirk Caldwell initiated the program, approved in 2015, as a means of increasing the number of affordable housing units on Oahu.

Councilman Ernie Martin said he introduced the resolution in response to a complaint he received from a Kailua family about being denied an ADU permit when other families in their neighborhood had already received their permits.

Environmental Services Director Lori Kahikina told committee members that the family was denied because of a recent change in the methodology her agency uses to determine capacity. While the methodology usually allows for greater capacity in a neighborhood, that was not the case in the Mapuana-Hele streets area.

The area is scheduled to get a sewage pipe expansion, but it won’t be completed for another four or five years, Kahikina said.

Kahikina said Monday that her agency’s priority was to complete $5 billion in mandatory wastewater system improvement projects by 2020, a requirement that is tied to a federal consent decree. Many of those projects will increase sewage capacity, but they are nonetheless driven by and prioritized by the mandate, not housing demand, she said.

On Wednesday, Kahikina said Caldwell has asked her to work with the Department of Planning and Permitting, which issues ADU permits, to look at what could be done across the island.

“I want to get from DPP … where are the areas being denied,” Kahikina said, adding that the Environmental Services Department wants to install flow monitors into the pipe system and see how much can be handled during heavy rain. If it’s determined that the city’s estimates were not accurate, a denial may be overturned, she said.

DPP Acting Director Kathy Sokugawa said there are several types of denials for ADU pre-applications: absolute denials, applications that are pending expansion that’s “on the books,” and those that are pending active city sewer projects and are “just a matter of months.”

The city’s Kaneohe-Kailua gravity tunnel project, scheduled to be completed next year, will help Windward ADU applicants, Sokugawa said.

Another earlier barrier to obtaining an ADU permit, the high cost of sewage hookup fees, was taken care of when the Council passed a waiver on such fees last year.

Martin said he appreciated the administration’s willingness to improve the ADU program. “As much as possible, we want those who can benefit to benefit from the program,” he said.

Fukunaga suggested that the city should make public a map showing “infrastructure deficiencies” around the island.

Sokugawa acknowledged that the information available to the public is also “not very user-friendly” and will try to make improvements to it.