MIDDLETOWN — Protection of south Lake County groundwater is at the hub of a long-term Pacific Gas & Electric project involving the cleaning up and closure of a former 40-acre geothermal waste site on Butts Canyon Road.
The Central Valley Regional Control Board as the lead agency and a number of other agencies, said Project Manager Sally Goodin, has achieved the closure, with regulatory oversight.
“There were two objectives for the closure,” Goodin said. “One was to take the waste and consolidate it into as small an area as possible. The second was to create separation from ground water. We must achieve separation from the bottom of the waste and ground water.
“We really wanted to provide as much separation as we could,” she added. “That”s what provides protection to the overall environment.”
Goodin was one of several representatives of PG&E present for a public meeting at the Calpine Visitor Center on Wednesday to lay out the work that the utility has completed in its project to mitigate environmental problems created by the waste site.
The site was the GI facility from 1976 until it lost its permit to operate a dump in 1986. Shortly thereafter, the company went bankrupt.
“They took the mixture of solids and fluids and dug trenches to bury them,” said Goodin. “Later on in the 80s, they simply allowed the waste to accumulate in the bottom of a pond.”
After the bankruptcy, closing the facility became the responsibility of companies that had worked with GI. These companies developed a committee, Goodin said, and implemented the purchase and takeover of the waste site by PG&E. In short, that”s how PG&E became the sole owner of the site and the sole party responsible for its cleanup.
Central to the cleanup has been the creation of a landfill in which 186,000 cubic yards about 14 acres of waste that was excavated out has been buried, said Kerry Parkinson, another PG&E representative.
To ensure that the sludge and contaminants did not leak into the ground water beneath the site 20-by-200 feet plastic sheets that were welded together were laid about 50 feet down in the landfill.
“Our job was to make sure the welds were performed properly and were watertight,” Parkinson said.
Clean soil was then placed on top.
“There”s no way it (contaminants) could penetrate,” Goodin said. “First it would have to get through the soil, and even if it did, there”s the plastic cover.”
Another important step was the solar evaporation of wastewater in ponds.
Eucalyptus trees were planted around the site because of their effectiveness in sucking up moisture. Additionally, about 2,000 trees were replanted.
Solidifying the soil required borrowing clean dirt from areas near the site to mix with existing soil.
“We brought in the dirt because you can”t move this stuff (waste) because it”s dripping,” said Parkinson. “We don”t want to have it dripping across the road.”
As another touch, PG&E has brought in a herd of goats which nibble away at the ground cover.
“We brought them in for weed abatement to create a fire break, actually,” said Goodin. “So far, they”ve been pretty good employees.”
The structural part of the project involving these components, she added, took about three years to complete.
Michael Raub, another of the PG&E representatives present, said he has been monitoring the project so thoroughly that he rented a house in Hidden Valley for a while.
ENV America, an engineering company, has provided oversight. CH2M Hill has provided permitting, construction and environmental monitoring. Locus was the prime construction contractor and Geomatrix developed the closure plan and groundwater supervision.
If the PG&E project is successful, a minimum vacuum of about 10 feet will separate groundwater and the ground covering over it. About 70 wells on the site, some close to the landfill, will provide ground water samples and depth readings.
“We”ll be monitoring the site for about two years,” Goodin said. “We have a lot more to do to make sure that what we”ve done and what we want to do is working.”
Said Marti Steiner, another PG&E spokesperson, “We will be back. We are not going away. We will have it set up where we can report on various activities.”
Goodin said the advantage of the PG&E project is that it will keep working without requiring maintenance.
“The approach is preferable to a lot of people,” she said.
Asked if he was comfortable with the PG&E way of doing things, District 1 Supervisor Ed Robey replied, “Hmm … Comfortable? I don”t know about that adjective. I”ve been watching this project ever since I”ve been on the board and I am confident that PG&E is doing the best job they can.
“But comfortable? I”d like to wait another year or two until they have enough data on the groundwater level. I”m optimistic, but I don”t get comfortable very often.”
Contact John Lindblom at jlwordsmith@mchsi.com.
