Challenge

The Mid-Valley Sanitary Landfill in San Bernardino County required the phased construction of seven double composite liner systems to support ongoing expansion while maintaining strict regulatory compliance and long-term environmental protection. The technically complex project involved engineered fills, low-permeability liner systems, geosynthetics installation, leachate collection infrastructure, stormwater controls, and geotechnical evaluation across multiple construction phases. Maintaining liner integrity, verifying material performance, and documenting compliance throughout construction demanded a highly experienced construction quality assurance (CQA) team with deep geotechnical and geosynthetics expertise.

Solution

GLA provided comprehensive CQA services for Unit 3, Phases 1 through 7, and Unit 4, Phase 1, overseeing all aspects of liner system construction and quality verification. Our team conducted stability analyses, geologic mapping, excavation monitoring, subgrade evaluation, and review of design drawings and technical specifications to support constructability and performance objectives.

During construction, GLA implemented an intensive field testing and observation program that included gradation, moisture-density, permeability, and compaction testing of low-permeability soils; observation and documentation of geosynthetics delivery, deployment, and welding; destructive seam testing coordination; and monitoring of LCRS installation and protective cover placement. We also prepared the project-specific CQA plan, evaluated potential liner materials, documented daily construction activities, and compiled comprehensive certification reports for agency review and approval.

Our oversight extended through stormwater retention basin construction, leachate collection infrastructure installation, and subsequent partial closure activities, ensuring each phase met rigorous engineering and regulatory standards.

Results

GLA successfully supported the construction and certification of multiple landfill expansion phases, helping the client deliver compliant, high-performance containment systems designed for long-term environmental protection. Through proactive field oversight, disciplined testing protocols, and detailed regulatory documentation, the project achieved approval from the County of San Bernardino Solid Waste Management Division and the Santa Ana Regional Water Quality Control Board. The completed liner systems provide durable containment performance, operational reliability, and regulatory confidence for one of Southern California’s critical solid waste management facilities.