State Directs County To Fix Flaws In Central Maui Landfill Phase IV

posted in: June 2004 | 0

“The DOH cannot give a permit for a landfill, constructed without a permit, if things are already failing…. It’s like driving your new car with a spare tire already.” – Gary Siu, Department of Health Solid Waste Branch

For years, the state has been a stone wall to Maui County’s pleas for a permit to operate Phase IVA of the central Maui landfill, construction of which was finished in 1999. Earlier phases of the landfill had been filled to overflowing even before Phase IVA was built. Since then, the county has begged, argued, and thrown engineering reports at the DOH in an effort to open the new unit.

All to no avail. The $7.2 million facility remains closed.

At a glance, Phase IV looks good. It’s a 10-acre pit in the ground, lined with plastic and blanketed with a cushioning layer of dirt. An underground pipe pokes through the pit’s bottom to carry leachate from the sump to a plastic holding tank. From there, leachate can be pumped into a nearby lagoon, where evaporation reduces its volume.

To the man on the street, the design might appear sound, and according to DOH solid waste engineer Gary Siu, that’s been a major problem: Non-experts making judgments on the fitness of the landfill.

Siu is the lone engineer in the DOH’s Solid Waste Branch and is solely responsible for ensuring that all of Hawai’i’s landfills comply with state and federal solid waste laws. That lack of staff, too, has contributed to Maui’s problems in opening the landfill.

John Harder, once head of the DOH Solid Waste Branch and now Maui County’s solid waste director, believes the DOH – that is to say, Siu – should provide technical assistance and guidance to the counties. But with one man to do the job, Harder says, it’s difficult.

Arguments over blame aside, the conclusions contained in an independent consultant’s report last November suggest that the Department of Health’s long-standing reluctance to grant a permit may have been justified.

Garbage In…

Phase IV of the Central Maui Landfill was a mess practically from the start. In 1996, the county first hired local engineering firm Masa Fujioka & Associates to design the new phase, which, according to MFA’s final plans, was to span 26 acres and cost $5.7 million. But after the construction contract had been awarded to Rojac Construction, Inc., the county invited in another engineering firm, Parametrix, Inc., which argued that the MFA design didn’t adequately provide for leachate, the liquid at the bottom of the landfill that is caused by rain and other fluids in the fill percolating through the tamped down garbage.

In 1998, through a process called “value engineering,” Parametix redesigned the landfill to include a large leachate lagoon. But instead of saving the county money, as the project was intended to do, construction costs under the new design ballooned to $7.2 million while the size of the landfill shrank to 10 acres.

The fact that Rojac was working on the landfill at the same time Parametrix was redesigning it didn’t help matters. Impatient with the DOH’s review of the new, constantly changing plans, the county allowed Rojac to build the 10-acre landfill cell in 1999 without a DOH permit. Since then, the cell has sat idle while the DOH has fought to correct what it sees as critical flaws in the landfill’s design assumptions and construction. (For additional background, see articles on the landfill in the [url=/members_archives/archives_more.php?id=678_0_25_0_C]April 1999[/url] and [url=/members_archives/archives_more.php?id=386_0_22_0_C]September 2002[/url] editions of [i]Environment Hawai’i[/i].)

As Peter Fuller, a geologist with California’s Land Disposal Program, wrote in a review of the Parametrix value engineering study and a May 2002 report by county engineer Elaine Baker defending the Parametrix work, “Overall, the two reviewed documents … do not provide useful information justifying the design and do not show the kind of professional competence that is necessary for a good landfill design. If these documents were submitted to the State of California, they would be returned as incomplete and inaccurate. The level of competence shown by this design is below the minimum qualifications for a review by the state of California.”

So in March 2003, Masa Fujioka & Associates met with Maui’s solid waste staff to discuss the facility’s technical problems. In July 2003, at Maui County’s request, MFA submitted a proposal to “develop technical and regulatory solutions to the ongoing issues preventing the Central Maui Landfill from being placed in service.” MFA planned to work with A-Mehr, Inc., of Laguna Hills, California, a consultant that specializes in the design and operation of solid waste landfills and has worked on landfills on O’ahu and Hawai’i.

A-Mehr completed its evaluation of Phase IVA in November 2003 and in February 2004, the DOH followed up with a list of 21 recommendations to the county addressing corrective actions, operations and future cell construction.

Isolation Given all the problems found in Phase IVA, A-Mehr issued a harsh recommendation. Although the cell is “generally acceptable for use following additional recommended testing and revisions,” its report states, “due to certain aspects of the design, issues related to construction quality and uncertainties in the [quality assurance] documentation, we recommend certain limitations on use and future development of the cell. Specifically, we recommend that Phase IVA be designated an isolated unit with its liners and LCRS [leachate collection system] to operate independent of future additional cells.”

Some of the obvious problems A-Mehr identified had already been called out by the Department of Health, including:

An Unstable Berm: Sloping earthen berms surround the Phase IV’s boundary. A-Mehr found that the berm separating the landfill cell from the leachate lagoon was never fully compacted and is potentially unstable. Once Phase IVA is opened, trash will pile up, and the weight pressing against the berm may cause it to shift. If it shifts, the landfill’s liner could tear in the worst possible place – the sump. To keep the liner from tearing, Siu says the county may one day have to inject cement into the berm to firm it up. In the meantime, the DOH recommended that the county equip the berm with so-called “monuments” that can be used to monitor any settling, and that it provide regular reports on settlement to the DOH for at least five years.

Operations Layer: When a lined landfill is built, before it’s put in use, a thick layer of soil must be laid down to prevent the liner from being damaged by the trash or the trucks hauling it in. The industry standard for this layer, called the operations layer, is 36 inches. When Parametrix was redesigning the landfill, it sought to increase the amount of usable volume in the landfill by reducing the operations layer to 18 inches.

Failed Waterproofing: One of the more unusual features of Phase IVA is the leachate manhole, a kind of tank outside the landfill that holds leachate before it’s pumped into the lagoon. The DOH and A-Mehr found in their inspections that the manhole’s waterproofing had failed. Siu says that the epoxy sealant applied inside the concrete manhole is already cracking. To keep the leachate from penetrating the porous concrete, the DOH recommended installing a thick plastic liner in the manhole.

Run-off: In violation of state and federal laws regarding the design of surface water controls in landfills, A-Mehr found, Phase IV has no barriers or other systems that would prevent storm water run-off from entering the landfill.

Leachate Control

The DOH’s biggest concern about the landfill is leachate management. The primary liner in the leachate lagoon leaks. According to A-Mehr, although there appear to be no leaks in the secondary liner, “the absence of a leak cannot be confirmed… The evidence of leakage from the primary liner suggests that some defects may not have been corrected.” In addition to repairs and the addition of a third liner, A-Mehr recommends that the lagoon “be used only as a backup storage unit for leachate. Instead of being pumped to the lagoon, A-Mehr recommends the leachate be pumped into large tanks.

According to a model A-Mehr ran to determine the potential leachate from a 24-hour, 25-year storm, Phase IV could generate 17 gallons of leachate per minute. That’s far below Parametrix’s figure of 1,033 gallons per minute – the estimate that it used to justify substituting the 10,000-gallon holding tank proposed in the MFA design with a multi-million dollar leachate lagoon system.

To allow for overflow capacity in the event of multiple storms, and in light of the fact that it takes time to move leachate from the tanks to a wastewater treatment plant, the DOH recommended the county have enough tanks to contain 100,000 gallons of leachate.

The county originally planned to let leachate pond in the lagoon until it evaporated. “Winter rain will sit there until summer,” Siu says. If the lagoon is used, he says, “it better not leak.” But because the lagoon’s liner is not self-sealing and was found in tests to be leaking, the DOH did not want the lagoon used at all.

The risks are just too high, Siu explains. Water from the aquifer beneath the landfill is used to grow food crops, he says, and as Maui’s population grows, it’s likely the aquifer will be needed for drinking water. Siu adds that EPA studies that show 80 percent of liner damage occurs after the liner is in use. “No liner is perfect. All liners have some damage. That is why they have to be self-sealing,” he says. (A self-sealing liner consists of a plastic liner on top of a clay liner. If the top layer is punctured, moisture will cause the clay beneath to expand and plug the hole.)

Peter Fuller, the California engineering geologist, notes in his 2003 report to the DOH, “Leachate pond liners in California are required to be as, or more protective than landfill liners because of the greater danger presented by the risk of groundwater contamination.”

Harder has taken steps in line with the DOH’s concerns, but does not seem overly concerned about leachate somehow making its way to the aquifer. Based on climate and hydrology of Central Maui, as well as other dry areas like Waimanalo Gulch on O’ahu’s Wai’anae Coast and Kekaha on Kaua’i, he says, “Once you’ve got 10 to 15 feet of trash, you’re not going to see any leachate. The trash acts like a sponge.” Waimanalo Gulch, he says, generates only 5,000 gallons of leachate a year. “Even if the liner fails, its not a total catastrophe,” he says.

Harder also argues that although the DOH says Phase IVA’s double plastic lagoon liner does not meet requirements, “the DOH doesn’t have lagoon liner requirements.” There are no plans to make the lagoon liner self-sealing, but because of the DOH’s concerns, Harder says the lagoon will sit empty, at least until Phase IVB is completed. “It’s more of a technical issue than a real issue,” Harder says. To allay DOH’s concern’s about the lagoon, Harder says, “Maybe we’ll use it for asbestos or other friable products.”

In light of the DOH’s February letter spelling out the totality of its concerns over the lagoon, Harder’s Plan B might make the most sense. The DOH sets the following conditions on use of the lagoon for leachate: “Quarry spalls and drainage rock” must be removed form the access ramp, leveling soil must be placed above the drain rock on the floor, the plastic liner’s side slopes and ramp must be repaired and tested for leaks, a third liner of geosynthetic clay and plastic must be installed on the floor and five feet up the side slopes, and the county must provide a rationale on the “total head and time that leachate may remain in the reconstructed leachate pond. However, the pond shall not be used as an evaporation pond unless the reconstruction consists of a lower composite liner and an upper geosynthetic liner with a drainage layer in between.”

A New Leaf

On March 23, the county agreed, with minor modifications, to all of the DOH’s recommendations, and had already increased the landfill’s operations layer to 36 inches. On April 23, the DOH gave its permission to the county to start remedial construction.

Harder says he thinks he’ll be able to start piling trash in Phase IVA this summer. Siu, on the other hand, is more cautious in his predictions. Once the fixes are done, they must be reviewed by a third party for quality assurance, he says. Only when the DOH accepts that review and has made sure all of its conditions have been met will it issue the county a permit to operate.

— Teresa Dawson

Volume 14, Number 12 June 2004

Leave a Reply

Your email address will not be published. Required fields are marked *