Planning ahead at Central Peninsula Landfill

There’s a lot going on at Central Peninsula Landfill.

Up the hill from the big blue building where most members of the public drop off their trash, workers with excavators and soil compactors are busy putting together infrastructure to last the landfill into the next decade and beyond. At the center of that activity is an enormous pit that is much more than a pit.

Cell 3, which covers approximately 5.4 acres, will serve as the main disposal point for the Kenai Peninsula Borough’s municipal solid waste in the future. The contractors building it should be done by the end of the summer, said Kenai Peninsula Borough Solid Waste Director Jack Maryott.

The cell contains a lot of careful engineering, from the slight grade tipping it downhill to the multilayered liner that goes on the bottom and side slopes to the pipes connecting it into the landfill’s multi-cell system. It cost about $3.4 million to build, with $300,000 in design and engineering alone, Maryott said.

The liner has a number of components meant to contain the leachate — liquid generated by decomposing trash — and allow the managers to actively treat waste to help it decompose rather than burying it dry. Beneath the layer of soil is a fabric layer, a geotextile meant to transport liquid, a thick plastic layer and a cloth layer that contains clay, meant as a stopper in case any liquid gets through the plastic. That is all required by the U.S. Environmental Protection Agency.

The new cell should serve the borough for five to seven years, if not longer, he said. Beyond that, the landfill managers are already working on the plans to build cells 4 and 5, the final two in the initial design for the system. And it’s possible that even after the initial capacity in Cell 3 is filled, they may get to go back and fill it in a little more, too.

That’s what the landfill workers are doing with Cell 1, the first lined cell, which hasn’t been actively used in several years. Brian Smith, who manages the operations at Central Peninsula Landfill, said the active decomposition of waste beneath the liner due to the treatment they do has given them some capacity back in the cell, which they are actively using. The solid waste department conducts a capacity study each year.

“(Each cell) has a design capacity and an actual capacity, and we’ll be able to determine that,” he said.

Central Peninsula Landfill is taking the bull by the horns on waste-handling technology. Instead of accepting trash and simply burying it they way landfills once did, Central Peninsula Landfill collects leachate and sprays the waste they’re burying with it. The wet garbage compacts better, giving the landfill more capacity out of each cell, and helps the trash decompose faster.

That leachate comes out of the cells through the buried pipe systems to a storage tank and lagoon nearby. Some of it is collected by trucks to treat the waste going into the cells; the rest is evaporated either by the sun or by a specific piece of machinery meant for just that. In July, it was sunny enough that the landfill was able to evaporate the majority of its leachate without having to actually burn gas to do so, Smith said.

On a warm day in early August, the leachate lagoon was nearly empty. The extra space essentially acts a buffer in case of a large rain event where they’d need to store a lot of liquid, Maryott said.

“I look at that (low level in the lagoon), and that makes me happy,” he said.

The leachate evaporator is part of the long-term plan to handle the landfill’s leachate and the gas generated by decaying garbage. Along the edges of the closed Cell 1, which is covered by black tarp, tall black pipes passively vent gas to the atmosphere. The borough is currently working with utility Homer Electric Association to study how to use that gas, primarily looking to use it as an alternative source of energy to operate the evaporator instead of natural gas, Maryott said.

Central Peninsula Landfill is one of two landfills in the state with a Research, Development and Demonstration permit through the Alaska Department of Environmental Conservation via the U.S. Environmental Protection Agency. Fairbanks also has one, and Anchorage and the Mat-Su Valley have also had them in the past but have since let the permits lapse, said Lori Aldrich, who manages the state’s landfill permitting program.

Though using leachate recirculation and evaporation system with lined cells isn’t brand new, it is technically still experimental and requires a research project, Aldrich said.

“You’re trying to show something with your project,” she said. “Basically, you propose a project, and in most cases, the purpose of it was to be able to recirculate their leachate and ultimately have less cost for managing the leachate.”

EPA originally allowed three renewals of the permits, for a period of up to 12 years. Soldotna, which has had the permit since 2006, is now coming to the end of its 12th year. EPA has extended the program renewals and is currently considering developing an advanced notice of rulemaking requesting information and data on the performance of wet landfills and bioreactors as well as requesting comments on whether the agency should make changes to the current regulations on wet landfills, said EPA spokesperson Tricia Lynn in an email.

If the EPA amends its rules, that would eliminate the need for a project demonstration permit and cut down on the documentation landfills doing what Central Peninsula Landfill is doing, Aldrich said.

The main cell isn’t the only thing Central Peninsula Landfill has been working on, though. Down the hill from the cell construction is a newly completed stormwater handling system, which will handle stormwater runoff that the landfill managers aren’t required to evaporate because it hasn’t come in direct contact with waste. Down another road toward Arc Lake is a site under preparation for an expansion of the construction and demolition waste cell as well, which should meet the landfill’s needs for another 12–15 years, Maryott estimated.

“We’re always thinking into the future here,” he said.

Reach Elizabeth Earl at eearl@peninsulclarion.com.