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Draft Supplemental Environmental Impact Report Page IV.G-14 Forward Inc. Landfill 2018 Expansion Project vertically on the east by wells AMW-5R,AMW-30S and AMW-30 and partially to the west by wells AMW-28,AMW-32S,AMW-32, and AMW-2. The north and west side EMPs are being performed to define the non-detection or zero. The zero line for the vertical and lateral extent of the plume to the northwest,north, and north-northeast is also under investigation. The overall shape of the VOC-affected plume with respect to groundwater contours and the distribution of VOCs between the shallow and deeper zones indicate the lateral and vertical limits of the VOC affected groundwater have likely been affected by regional flow conditions (agricultural/industrial pumping, recharge rates,etc.). In addition to the sampling at the CDCR, groundwater samples were collected from 51 residences between February 7 and May 18, 2018. Six of the 51 residential wells showed detected VOCs in the wells as reported by GLA(2018). Forward is continuing to assess landfill gas and groundwater issues at the Austin Road Unit and complying with RWQCB requirements for the CAP. The April 2009 installation of two new groundwater extraction wells at Forward increases the volume of groundwater being extracted and treated"at the source" and to an extent draws back the groundwater plume migrating offsite. Leachate Generation, Treatment, and Monitoring The northeast and southern WMU expansions proposed in this project would have Class II lining and leachate collection designs that comply with current requirements. The Forward Class II Surface Impoundments (i.e, leachate ponds)would be lined with high density polyethylene (HDPE)geomembrane. Both new areas would have the leachate collection and monitoring required (by the RWQCB)of the landfill operations, as described in the project description of the expansion. The new units would have blanket LCRS. The components of the LCRSs are summarized in the Project Description. The blanket LCRS described would be placed on both the base and slopes of the landfill expansion modules. The LCRS is the first line of defense for the protection of groundwater from any leachate generated from the landfill. There are currently two Class II surface impoundments at the Forward Landfill: WMU F-West and WMU F-North. An additional Class II impoundment,WMU F-South, is permitted but has not yet been constructed. A Compost Pond is located in the southern portion of the site (southern expansion area). Both Class II impoundments have 1:1 (horizontal:vertical)slopes, contain a sump with a side slope riser and a double liner system consisting of, from top to bottom: • 60-mil HDPE primary geomembrane • Geonet • 60-mil HDPE secondary geomembrane.