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eov <br /> STATE OF CALIFORNIA—ENVIRONMENTAL PROVION AGENCY PETE WILSON,Govemor <br /> CALIFORNIA REGIONAL WATER QUALITY CONTROL BOARD— g�`""�°, <br /> CENTRAL VALLEY REGION , <br /> 3443 ROUTIER ROAD,SUITE A <br /> SACRAMENTO,CA 95827-30984 <br /> FAX: (916)255-3015 000a�.. . <br /> q pp` 1 50 "«.m <br /> 5 April 1994 <br /> Mr. Gabriel Karam <br /> Solid Waste Division <br /> Department of Public Works <br /> County of San Joaquin <br /> P. O. Box 1810 <br /> Stockton, CA 95201 <br /> HARNEY LANE LANDFILL, SAN JOA IN COUNTY (Case No. 2598) <br /> We have reviewed the contract specifications for final closure cover construction at Harney Lane <br /> Landfill. Our comments are limited to the construction methods and construction quality assurance <br /> (CQA) aspects of the specifications. The proposed specifications may lead to a cap that does not <br /> comply with the requirement of Chapter 15 for at least one foot of soil with a permeability of 10-6 <br /> cm/s or less. U. S. EPA has published several documents,including the Subtitle D Technical <br /> Manual (EPA530-R-93-017),that provide soil liner design criteria,construction techniques, and <br /> CQA programs for liner construction. The approach described by EPA has been used extensively to <br /> produce well documented,low permeability liners and should be applied at Harney Lane. <br /> We recommend the specifications be revised as follows: <br /> Sec. 10-1 FOUNDATION LAYER-Section 2581 of Chapter 15 requires the foundation layer <br /> include not less than two feet of soil compacted to the maximum density obtainable at optimum <br /> moisture content. Revise the specifications to reflect this requirement. <br /> Sec. 10-1 CLAY BARRIER LAYER-Page 1: Delete reference to Regional Board. Borrow source <br /> and mixing methods were not"prequalified"by the Board. All materials and construction <br /> methods must comply with the project's design plan and CQA requirements. <br /> Sec. 10-1 CLAY BARRIER LAYER-Page 3: Moisture content is specified as 0 to 3 percent over <br /> optimum during compaction. Revise specification to require a minimum of 2 percent over <br /> optimum. Add a specification requiring a time period(e.g. 24 hours)between soil moisture <br /> conditioning(hydration) and compaction. <br /> The barrier layer needs to be constructed in two lifts to ensure adequate compaction using <br /> standard construction equipment. Revise the specifications to require construction in two lifts. <br /> Add a specification that compaction equipment be fitted with shanks that fully penetrate the lift <br /> thickness. <br />