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What's next for the Laytonville landfill

A view of a hill with a belt of riprap with trees behind it and a cloudy sky.

Chris Watt, of the North Coast Regional Water Quality Control Board, shares some details about plans to update the monitoring system at the county's closed landfill in Laytonville.

The closed landfill in Laytonville has long loomed large as a source of grief in the community. Some residents of the unincorporated area and the neighboring Cahto Rancheria are sure that contaminants are causing damage to the environment and their health. The bottom of the landfill is unlined, which means water can percolate into the historic waste and then back out again into the soil and groundwater.

The local water district tests some of the nearby wells and finds that the water is free of the most concerning contaminants. But in the last decade, increased levels of multiple different kinds of salts and minerals that are frequently associated with landfill waste have been found in a well on the southeast corner of the county’s monitoring network, which includes ten wells. And an environmental consultant working for the tribe says two of the three wells he’s working with show troubling indicators. He’s planning to install a half dozen more wells this year. The state has also called for more monitoring wells, as the county prepares for maintenance on the landfill cap, drainage system, and roads on the seven-acre site.

After government-to-government consultations between the tribe and the California Environmental Protection Agency, the county and the tribe have signed an MOU to work together on the project.

Chris Watt, of the North Coast Regional Water Quality Board, shared some context about what’s currently known about the elements in the county’s well, and why more monitoring is needed.

“This well at the southeast corner of the landfill has been monitored for multiple decades,” he said in a recent interview. “Beginning about ten or more years ago, that well, as we looked at the statistics, began to record an increasing trend in what we call indicator parameters. Indicator parameters are minerals and salts that are present in the groundwater. And we are seeing increasing values of those over time. Landfill waste can generate those salts and minerals, so our assumption is that those are originating from the landfill, and show that there is movement of groundwater from the landfill through that well. All of these are found naturally in the groundwater, so they’re not what we would call synthetic contaminants. They can be associated with the landfill waste, and they can originate from either those minerals and salts dissolving into the groundwater as water moves through the waste, or they can be dissolved through the rocks as the landfill waste changes the chemistry of its environment. So these aren’t what we would traditionally call pollutants, per se. They’re indicators that there is movement of groundwater from the landfill in the direction of that well. Some of these have exceeded what we would call secondary drinking water standards. So we are tracking this, and asking the county to expand their monitoring network to determine how far and where this movement of salts and minerals has gone.”

Watt says it’s significant that the southeast corner is most affected by the landfill. “Traditionally, the model for how water has moved in this area of the landfill has been, it’s moved in a northerly direction,” he noted. “However, this trend in indicator parameters, these salts and minerals that we’re finding to the southeast, suggest that there is a component of flow to the southeast. This is going to require an update in our conceptual model of the landfill and in the monitoring program for the landfill, which the county is working on as they prepare their engineering documents to do a fix on the landfill cap…at a minimum, it’s going to be an expansion of the monitoring well network to the southeast. The county’s land that they control ends near this well, so they’re working with their neighbors, the Cahto Tribe, to obtain access and design a monitoring program that’s going to have to be located on the Rancheria property.”

The exact number and location of the new wells hasn’t been worked out yet. The county will hire a contractor, who will meet with the Cahto Tribal Council and the Laytonville Municipal Advisory Council, and then present a proposal to the Water Board for its review, before installing more wells. Nothing will happen in a hurry. Massive cleanup is one of many possible outcomes, but Watt thinks it’s too early to predict what will come of the increased monitoring.

“So there’s a monitoring program that the county implements, that’s a series of wells,” he summarized. “Some of them are for water, some of them are what we call a gas well, so they do gas samples. Landfills can generate gasses, and so they monitor that as well. The monitoring network, I think we’ve established, needs to be changed. The county has been monitoring these wells for decades. There are thousands of data points which we are using in our conceptual model of evaluation…This last ten years of data has said we need to change this. Things with landfills don’t move quickly, in terms of actions. They’re expensive, they’re complicated, they’re technically difficult, they require specialists. So some of this just takes time. But I think we’re going in the right direction now.”

There will be several opportunities for public engagement in the next two years, which is how long Watt and the CalEPA expect it to take to update the monitoring system. In addition to the public meetings with the county’s consultant, the county will prepare an environmental document for the landfill repair, which will include a public comment period. The Water Board will hold a public hearing prior to issuing an updated permit for the landfill. “And that will guide us into the future for this landfill, wherever it goes,” Watt concluded.

Local News
Sarah Reith is the lead reporter for KZYX News. She joined the KZYX News team in 2017, and covers local politics, water, law enforcement and the arts in Mendocino County.