Advanced Earth Sciences (AES) provided construction quality assurance (CQA) services for earthworks, composite liner and Liquids Collection and Removal System (LCRS) for a 32-acre cell for Canyon 3 expansion. This is the largest single lined cell undertaken by the Riverside County for this 4,000 tons/day landfill. The expansion involved excavation of 5.7 million cu. yds. of bedrock and creation of 1.5:1 side slopes up to 350 feet high above the canyon floor. The lined area included about 7 acres of canyon floor and 25 acres of side slopes. The composite liner system construction involved placement of about 20,000 cu. yds. of clay liner on canyon floor and over 5 million sq. ft. of geosynthetics on floor and side slopes. AES’ scope of services included geologic mapping of cut slopes, preparation of design modifications as warranted by exposed geologic conditions, and performing CQA services for earthwork and geosynthetics. The scope also included geologic observation and documenting abandonment of three groundwater monitoring wells.

AES performed field observation and testing services to verify compliance with project plans and specifications and to prepare CQA documentation for the regulatory agencies. The key CQA activities for earthworks included observations and geologic mapping of cut slopes, design and construction of buttress fills to stabilize major landslide areas and areas with out-of-slope bedding, installation of seepage control measures on side slopes including drainage geocomposite and subdrain system and observation and testing of over 200,000 cu. yds. of engineered fills and 20,000 cu. yds. of clay liner material. The geosynthetics included installation of HDPE, GCL, geotextile and geocomposite.

The key CQA activities for geosynthetics include: review of manufacturer’s quality control (MQC) data for compliance with specifications; collection of representative samples for conformance testing; observations during deployment and installation; field observation during seaming and non-destructive seam testing at site; collecting HDPE samples for destructive seam testing at site; and documenting all field and laboratory test results. At the completion of CQA services, AES prepared an as-built report documenting as-graded geologic conditions and presenting results of field and laboratory CQA tests. The report was reviewed and approved by the Regional Water Quality Control Board (RWQCB) without any comments.