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Geosyntec CONSTRUCTION MEMORANDUM #2 Area 2A Expansion Foothill TO: Taj Bahadori, P.E. (San Joaquin County) FROM: Krzysztof Jesionek, P.E. (Geosyntec Consultants, Inc.) DATE: 14 July 2015 COPY TO: Awni Taha, P.E. (San Joaquin County) Michael Raub (Advances Earth Sciences, Inc.) SUBJECT: Granular Drainage Material Test Pad Part 2.04.E of Section 02300 of the Construction Specifications' for the Area 2A Expansion at the Foothill Sanitary Landfill in San Joaquin County, California, requires Granular Drainage Material (GDM) particles to be rounded to subrounded in general accordance with ASTM ® D2488; this requirement was developed to minimize the potential for puncturing the HDPE geomembrane under the anticipated construction equipment loading. The GDM proposed by the Contractor is Cemex 5/16" x 1/8" pea gravel (Kerlinger #4409 Tracy) (Submittal 41024-G) and does not meet the rounded to subrounded criterion in the specifications because it has a significant percentage of angular to subangular particles. Therefore, as required by Part 1.04.B.6 of the Specifications, the Contractor performed a field demonstration to evaluate and demonstrate that the proposed GDM materials and construction methods to be used during construction will not result in damage to the HDPE geomembrane (GM). On 13 July 2015, a test pad was constructed in the southwest corner of the Area 2A Expansion over the already -approved "Prepared Foundation Layer." In accordance with Construction Memorandum #1 (CM #1), the Contractor constructed an approximately 50 -ft long x 20 -ft wide test pad consisting of the following materials (from the bottom up): 12 -in. thick prepared foundation layer (Geosyntec understands that this layer was previously approved by the CQA Consultant); geosynthetic clay liner (GCL) — NWL-60 GCL, manufactured by GSE Environmental, Inc.; ' San Joaquin County, "Specifications (Including Special Provisions, Notice to Bidders, Bid and Contract) for the Construction of Area 2A at the Foothill Sanitary Landfill," Department of Public Works, 10 December 2014. P\SJC\l780\Task 6.1\CM #2 (GDM Test Pad) engineers I scientists I innovators