Clovis Sanitary Landfill, Clovis, California. Client: City of Clovis

BSK’s environmental and geotechnical engineering services to the City at the Clovis Landfill date back to the mid-1970s with the preparation of a Landfill Master Plan, Design, Drainage, Liners and Seepage Control. Subsequent services included the installation of groundwater and soil gas monitoring network, monitoring identified releases of volatile organic compounds and the Evaluation Monitoring Program (EMP) was developed and implemented to investigate the extent of the problem.  The site hydrogeology is complex; groundwater containing VOCs was found in fractured bedrock, metamorphic rock, decomposed metamorphic rock and alluvium.  A creek at the base of the landfill effectively acts as a boundary to horizontal migration of VOCs. The extent of VOCs in groundwater has been defined.

Additional issues confronting the City included excessive levels of methane at the landfill boundary, limited air space (active life) and shortage of cover material.  To address these issues, BSK recommended in 1996 that a feasibility study be performed to evaluate the viability of reconstructing the unlined portion of the landfill (comprising about 20 acres with 2.5 million cubic yards of landfill materials).  The feasibility study concluded that reconstruction would generate sufficient materials for daily cover needs, add an additional 15 years to the active life, and address landfill releases to groundwater through source elimination.  Subsequent monitoring has identified concurrent declines in groundwater VOCs and in landfill gas methane concentrations.  The landfill reclamation was completed in 2010 and extended the useful life of the landfill by an estimated 35 years.

BSK currently performs the following Detection and Correction Action Monitoring Program tasks at the Clovis Landfill:

• Monthly sampling of landfill leachate
• Quarterly perimeter screening of methane monitoring wells
• Quarterly water level measurements
• Semi-annual groundwater monitoring
• Semi-annual monitoring of pan lysimeters/vadose zone
• Surface water sampling
• Preparation of Semi-Annual Monitoring Reports
• Five-Year Sampling for groundwater, leachate, and surface water
• Installation of groundwater monitoring wells

BSK also has provided the following services to Clovis Landfill:

• Evaluation Monitoring Program
• Sampling and Analysis Plan
• Non-Water Release Corrective Action Plan
• Water Release Corrective Action Financial Assurance Plan
• Subsurface Drainage Collection Design Consultation and Construction Oversight
• Liner Construction Earthwork Observation and Field Testing
• Geologic and Hydrogeologic Investigations
• Storm Water Pollution Prevention Plans
• Investigations of Subsurface Drainage Discharge Treatment and Reuse
• Soil Gas Monitoring Well Destruction