The Honolulu Board of Water Supply is concerned that Oahu’s next landfill could contaminate drinking water.

“Although there are mechanisms and technologies available to try to protect the environment … such systems can fail and contaminants from landfills have been found in the groundwater,” Erwin Kawata, head of BWS water quality division, said at Tuesday’s Landfill Advisory Committee meeting. “We are 100% dependent on groundwater. It is our only source of drinking water.”

But the Honolulu Department of Environmental Services said its options are limited because a 2020 state law eliminated almost all of the sites it was previously considering. Now, there are only four areas that comply with local, state and federal regulations. And all four are above drinking water aquifers.

“The areas that we are showing, those are not preferred areas or anything like that,” Wesley Yokoyama, director of the Department of Environmental Services, said. “These are the areas that are left.”

Senate Bill 2386, signed into law in 2020 as Act 73, said that landfills can’t be in conservation zones or within a half-mile of a residential, school or hospital property line. Environmental Services said Act 73 removed every site that wasn’t above a drinking water aquifer, many of which were on the Westside, from consideration. The legislation was proposed by the Association of Hawaiian Civic Clubs in 2019 and championed by the Office of Hawaiian Affairs, Unite Here Local 5, Sierra Club of Hawaii and many Westside residents who are tired of hosting the island’s major public works facilities.

“In terms of trying to prevent contamination of a vital resource, it works against it,” said Ernie Lau, chief engineer at the Honolulu Board of Water Supply.

But Lau said that the recent fuel leak at Red Hill, which contaminated a drinking water aquifer, has opened the door for amending the 2020 law.

“The attention that right now is being focused on our precious drinking water resources and how we can preserve and keep them clean and uncontaminated may be an opportunity to revisit some of the constraints that are created by legislation,” he said.

The Landfill Advisory Committee, a group of nine members selected by Mayor Rick Blangiardi to advise the City and County of Honolulu, has until Dec. 31, 2022, to recommend a site for the island’s next landfill.

Yokoyama, the Environmental Services director, said that the LAC has the power to decline to recommend any of the four available areas, but that would make meeting the Dec. 2022 deadline impossible.

“The strongest alternative would be either an exemption or changing the Act 73 law,” Yokoyama said. “But that’s not something that we really want to do. There’s a lot of people that backed this law for reasons.”

Drinking Water Impact Ranked Highest In Survey

The island’s only municipal waste landfill, Waimanalo Gulch Sanitary Landfill, is required to close by March 2028, and it takes years of construction before landfills can accept any waste.

The LAC members have backgrounds in government, engineering, contracting, community organizing, environmental justice and agriculture and are tasked with rating each potential site based on objective criteria, subjective criteria and community input.

Environmental Services presented the first batch of results from a wide-ranging residential survey. Most of the 476 respondents listed “Distance to Surface and Drinking Water” as the most important criteria to consider.

John Katahira, the LAC meeting facilitator, noted that the survey results were collected before news of the Red Hill fuel leak broke, and said he anticipates that the next batch of respondents will rank drinking water impact even higher.

The distance between the landfill and homes and nearby population density was listed as the second most important factor with distance to important agricultural lands, archaeological and cultural sites and sensitive ecological areas third.

The city is pushing for the island’s next landfill to have two liners, which surpasses federal requirements and could significantly increase costs. Waimanalo Gulch Sanitary Landfill opened with a single-liner system in 1989, but since 2010 all new construction at the site has used a double-liner system.

The Waimanalo Gulch landfill produces about 9,800 gallons of leachate, or contaminated water from the landfill every day. That water is pumped out and transported to wastewater treatment plants. There haven’t been any detected leachate leaks from the Waimanalo Gulch landfill, but the site also doesn’t sit above any drinking water aquifers.

During his presentation, BWS’s Kawata cited a finding from the U.S. Environmental Protection Agency that all landfills eventually leak into the environment. Ash from H-Power, the island’s waste-to-power incinerator, makes up the bulk of waste buried at the Waimanalo Gulch landfill. Kawata said these contaminants present unique challenges.

“Landfills can contain a very complex array of different kinds of pollutants,” he said. “If the contamination is at a level that exceeds the ability to treat then treatment is no longer an option.”

At the next LAC meeting, scheduled for Feb. 7, members will finalize the list of criteria that will be used to score and rank potential landfill sites. The draft list has a site’s potential impact on groundwater evaluated alongside the site’s distance from H-Power, construction costs and landfill capacity among other considerations.

“The Landfill Advisory Committee will have some hard decisions to make,” said Yokoyama. “The criteria and the ranking will reflect what is more important, what the priorities are.”