MIDDLETOWN ? The public was invited Friday to tour a former geothermal waste site in Middletown. PG&E representatives guided tours explaining ongoing closure procedures for the past 10 years.
PG&E assumed responsibility of the 40-acre landfill site, which was once owned by Geothermal Inc. The GI Facility, located about three miles southeast of Middletown on Butts Canyon Road, operated from 1976 to 1986. It consisted of evaporation ponds and solid waste disposal trenches where numerous companies disposed of geothermal waste from drilling and power generation operations at the Geysers.
Following the bankruptcy of Geothermal Inc. a group of former customers who sent waste to the facility funded its closure. According to Sally Goodin, consulting project manager for PG&E, there were 17 cooperating entities when the closure initiated.
“Just the closure of the landfill was about $14 million. That doesn”t include investigation and permit and maintenance and monitoring costs,” she said. “This isn”t hazardous waste but it is Class 2 waste. There are affects on groundwater so we definitely had to do something.”
From 2003 to 2006, PG&E worked in coordination with local and state regulatory agencies to accomplish several tasks in order to clean and close the site. Procedures included solar evaporation of 21 million gallons of pond water and the excavation and solidification of 186,000 cubic yards of waste. It also included the closure of 30 acres of former waste evaporation ponds. “There were seven waste handling ponds but one of those had been cleaned and closed prior to (Geothermal Inc.) going bankrupt,” Goodin said. Closure and clean up of the ponds included the removal of sludge, grading, infill and the installation of impermeable barriers that will prevent rain water from reaching the landfill waste below. Remediation efforts include the grading of 90 acres to promote drainage and the planting of 32 acres of eucalyptus and poplar trees.
Goodin said eucalyptus trees were chosen to assist in lowering the water table. “Eucalyptus trees act as pumping wells,” she said they grow fast and consume water year round whereas most tree species go dormant in the winter.
Construction of four acres of new wetlands and additional habitat restoration was included in the project. The United States Army Corps of Engineers requires new wetlands be created when existing wetlands are impacted. A wetland mitigation program was developed and implemented in 2004. The mitigation program included the creation of about four acres of seasonal wetlands and vernal pools, the preservation of the newly created wetlands and about six acres of existing onsite wetlands via a conservation easement.
“This is our fifth year monitoring the hydrology. We come out four times a year,” Amy Hiss, biologist with CH2M Hill said. “What we want to do is make sure it is similar to the wetlands that exist on the site.”
Other efforts included the installation of a water supply and irrigation systems. The irrigation systems, Goodin said, operate via satellite. Provisions of fire breaks, fire water supply and fire access roads were also included in the clean up project.
