California Refinery Groundwater Collection System
Trihydro revamped an extensive California refinery groundwater collection system that was first commissioned in the 1980s. The inherited facilities were in disrepair and largely unable to achieve sustained and efficient operation. Our project team successfully implemented several rebuilds and new construction contracts, giving the system a dramatic facelift.
The project focused on satisfying regulatory remediation goals while preventing further fluid leaks and discharges. This resulted in a high-integrity groundwater collection system that intercepts shallow groundwater and creates a capture zone along a boundary of over 3,000 feet in length. The final system established boundary control of contaminated groundwater moving toward the facility’s key western property line and recovered vapor from the extraction wells.
Wellhead Controls and Equipment Replacements
The inherited wellhead controls and equipment posed significant maintenance challenges. Technicians were often unable to find spare parts for repairs. The original vapor extraction system was challenging to operate and had reached the end of its life. Flow restrictions and high backpressures made managing the original dual-pump layouts at the wells very difficult.
Our team undertook a phased replacement with a completely new design of materials at each extraction well, from the well caps to the manifolds. We also converted the well layouts to a total fluids system, realizing major cost savings and performance improvements.
Piping Network Replacement
When first installed nearly three decades ago, the collection system’s piping network relied primarily on fiberglass-reinforced plastic (FRP) piping. FRP deterioration weakened headers, which occasionally failed. The need to curtail fluid releases led to an exhaustive risk mitigation study, which prompted the decision to replace all FRP piping with carbon steel over time.
The routing of nearly two miles of FRP lines across the refinery presented major hurdles in certain pipe ways where space is limited and available slots are often at lofty heights next to hazardous process lines. Trihydro acquired an out-of-service steel pipeline to replace 900 feet of FRP line. This saved many months of dangerous construction activities and reduced overall project costs.
Thermal Oxidizer Installation
The original system relied on pneumatically driven downhole pumps that exhausted through hoses into a vent header system that discharged to an outdated thermal oxidizer. Due to the oxidizer’s large fuel requirement and escalating maintenance needs, Trihydro evaluated, permitted, and installed a new thermal oxidizer.
The new oxidizer was permitted under the site’s Title V permit, which required extensive modeling and coordination with the local Air Resources Board. Adding the new thermal oxidizer allowed for removal of a second outdated thermal oxidizer by connecting the existing soil vapor extraction wells to the total fluids system’s vapor recovery lines.
Current Groundwater Collection System Operation
The current total fluids system has been expanded to the site’s interior. It can be configured to recover total fluids from up to 64 wells, with additional vapor recovery from 10 soil vapor extraction wells. The system has recovered up to 120,000 gallons per day of total fluids and 90 pounds per day of hydrocarbon through vapor. The induced groundwater depression area creates a capture zone for total fluids along the site’s boundary.
