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PPP" EDMUND G.BROWN JR. 0rodeo GOVERNOR 0 CALIFORNIA MATTHEW RODRIOUEZ V-; SECRETARY IDI Water Boards ENVIRONMENTAL PROTECTION Central Valley Regional Water Quality Control Board 3 May 2017 R E C&Em-I V E 1) Taj M. Bahadori, P.E. MAY 10 2017 San Joaquin County Department of Public Works ENVIRONIMEN'TAL HEALTH P.O. Box 1810 PERMIPSERVICES Stockton, California 95201 REVIEW OF DESIGN REPORT FOR FILL AREAS 5B & 6, NORTH COUNTY LANDFILL, SAN JOAQUIN COUNTY Central Valley Water Board Permitting staff reviewed the March 2017 design report for construction of Fill Areas 5B and 6 at the North County Landfill (Engineering Design Report, Areas 5B and 6. North County Recycling Center and Sanitary Landfill, prepared by Geo-Logic Associates). The report provides design plans, construction drawings, project specifications, construction quality assurance (CQA), drainage analysis, and slope stability analysis for these fill areas, which will comprise about 11.7 and 11 acres, respectively. The landfill is regulated under Waste Discharge Requirements (WD s) Order R5-2010-0016. The first phase of Module 5 (Area 5A) was constructed in 2014 in accordance with a design report approved by Water Board staff in November 2014 (approval letter enclosed). The Discharger plans to construct the second phase of Module 5 (Area 5B) during the 2017 construction season. Area 5B will have the same engineered alternative containment system as Area 5A (see Enclosure 1), extending Module 5 to the east and south. Area 6 will be similarly constructed immediately south of Module 5 in the southwest corner of the landfill after filling Module 5 to interim grades. The leachate collection and removal system (LCRS) for each fill area will be constructed contiguous with Area 5A, and will share Area 5A's LCRS sump. As such, no separate LCRS sump will be constructed for Area 5B and/or Area 6. The LCRS for both fill areas will include east-west lateral piping draining to a header pipe along the western side of the landfill. The header pipe will drain north to Module 5's LCRS sump. See Enclosure 2. Monitoring systems installed for the two fill areas will include pan lysimeters (VZs-1 1 through 16) in trenches beneath the foundation layer at various locations, including beneath the liner blanket, lateral piping, and lateral-header pipe junctions. All pan lysimeters will be accessed by riser pipes extending along the western side of the landfill. A soil gas collection trench will also be installed beneath each fill area to allow for future connection to the LFG extraction system, if needed. A new groundwater monitoring well (G-9) will also be installed down gradient of both fill areas along the southwestern perimeter of the site. (A work plan for this well has not yet been submitted or approved). See Enclosures 2 and 3. Both fill areas will have a maximum interim waste elevation of 200 feet MSL and maximum interim slopes of 3.5H:1V with side slope benching for slope stability. Static slope stability analysis performed on Areas 5B and 6 based on the interim fill plan indicated stable interim slopes in both areas with safety factors of at least 1.5 for both areas. Global stability of the KARL E. LONGLEY SCD, P.E., CHAIR I PAMELA C. CREEDON P.E., BCEE, EXECUTIVE OFFICER 11020 Sun Center Drive#200,Rancho Cordova,CA 95670 www.waterboards.ca.gov/centralvalley C'p RECYCLED PAPER