The Hawaii Community Development Authority, the state agency that owns the Kewalo Basin small-boat harbor, deferred decision making Wednesday on a $20 million renovation and expansion project over safety concerns about a proposed fuel facility.

HCDA board members were scheduled to vote on a development permit Wednesday for the long-planned project by the Howard Hughes Corp., which last month revised its proposal to include the addition of 70 slips to the 144-slip harbor and a fueling dock that was earlier removed from the plan by the HCDA.

“My concern has to do with traffic in the harbor and potential for spills,” said Beau Bassett, the board’s cultural specialist, who repeatedly asked the developer to justify the fuel dock and the number of estimated boats that would be using it. “I’m thinking about the potential detriment to park users … surfers in the area. The more boats coming to fuel, the more potential for a spill.”

Howard Hughes executives estimate the harbor’s boats use at least 250,000 gallons of gas a year, filled primarily by private fuel trucks. The developer estimates between 15 and 20 boats a day would use a new fueling station that could generate 10 percent of the harbor’s revenue.

“How accurate is your 10 percent figure and where are those people coming from?” Bassett prodded. “I’m confused as to how this number was reached. Is it users coming from outside or is it going to be people renting slips? At the last hearing I asked a few questions regarding the expected use of the fueling facility and who the users are projected to be — something that hasn’t been addressed.”

Steven Scott, HCDA board vice chairman, said he was bothered by the building of the fuel tanks close to sea level, which could make it particularly vulnerable to tsunamis.

“I’m still concerned about having fuel tanks right there because if there’s any type of spill it would destroy Kewalo,” he said.

“If there is a tsunami of any size … we’re going to have the possibility of a fuel spill there that can’t be controlled. It’s 5 feet above sea level and it’s right there at the harbor mouth so I just see problems.”

Besides being a potential hazard, the decision to add a fuel dock also raised concerns of whether Hughes Corp. added it to boost income from harbor operations.

The developer earlier said it added the fuel dock with two 10,000-gallon tanks to improve access to fuel for tenants and to increase oversight compared with the current practice, by which boat operators pump gas and diesel from trucks largely after harbor office hours.

A fuel dock would be operated by harbor management and provide gas to tenants who don’t order enough to make it worth truck deliveries. However, fuel truck deliveries would still be allowed by Hughes Corp.

Kewalo Basin was once home to Hawaii’s aku boat fleet, but shifted to mainly tour, fishing and dive charter boat operations; meanwhile, facilities at the harbor degraded under the state Department of Transportation.

Hughes Corp. said its refinements were made after detailed study of the facilities, and represent improvements on the HCDA’s original vision that will deliver financial benefits to the state and better facilities and services to harbor tenants, which include charter boat operators and some pleasure craft owners.

The HCDA’s board, which supported the rest of the project, agreed to hold a public hearing to get answers on the fuel station on July 6 at 1 p.m. at 547 Queen St.