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As-Built CQA Report for the Construction of Area 2A at the Foothill Sanitary Landfill San Joaquin County,California • 5.0 FOUNDATION AND SUBGRADE LAYER PREPARATION FOR GEOSYNTHETICS INSTALLATION 5.1 GENERAL Preparation of excavated native material, earthfill and foundation layer soil subgrade for the installation of geosynthetics for composite liner for Area 2A liner construction was completed by R. J. Gordon prior to the start of liner construction. R.J. Gordon prepared the subgrade (foundation layer on the floor and sides lope subgrade) for the geosynthetic liner to provide a smooth, firm, and unyielding surface and to keep the protrusions/surface irregularities to within Y2-inch above the prepared surface. In general, the finish subgrade for geosynthetics construction was prepared immediately prior to installation of liner. Any rework, as deemed necessary, such as filling any slope irregularities or erosion rills with fine-grained material and compacting it, was performed prior to final subgrade acceptance. The limits of subgrade released for liner installation were recorded on subgrade acceptance forms, which were signed by the Geosynthetics Subcontractor (GBE) and the AES CQA Monitor. These forms are included in Appendix E.8 as documentation for accepted subgrade. 5.2 FLOOR SUBGRADE (FOUNDATION LAYER) PREPARATION • A CAT 14H motorgrader and CAT CS54B smooth drum roller were used to prepare finish surface and the subgrade was continuously watered until covered by geosynthetics materials. Grades were controlled by the motorgrader equipped with GPS controls. The Contractors surveying firm, F3, verified lines and grades to document that they conformed to the design grades. Surface irregularities were minimized by compacting finish surface with a CAT CS54B smooth drum roller. Minor repairs to the surface were made as needed during geosynthetics placement. Particles protruding more than 1/z inch above finish surface were picked out manually. 5.3 SIDE SLOPE SUBGRADE PREPARATION The Contractor's personnel prepared side slope subgrade by raking and picking out oversized particles from the graded slope surface. Following slope preparation, the slope surface was moisture conditioned by a water truck and the surface was rolled by a smooth drum roller with a side boom attached to a CAT dozer. Following initial preparation and rolling of the surface, the laborers corrected and maintained the slope surface until the geosynthetic materials were deployed. • PA14 Projects114-101(SJCDPW North County and Foothillffoothill CQAIReport\Final ReportToothill CQA Rport-Final.docx 10 16