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• • Draft Supplemental Environmental Impact Report Page IV.G-12 • Forward Inc. Landfill 2018 Expansion Project compliance wells MW-2A,MW-16, and MW-17. In addition, concentration limits (CLs) for several inorganic constituents have also been consistently exceeded in well MW-10, MW-18, and MW-19. The VOCs and inorganic CL exceedances are believed to be associated with landfill gas. • GLA performed an investigation to assess the source and potential impacts of low-level VOCs • in groundwater adjacent to the Forward Landfill (GLA 2017c,d). The investigation concluded that the low-level VOCs in groundwater(and lysimeter samples) at the original Forward • Landfill are most likely due to landfill gas from unlined unit WMU B. This is based on the fact that WMU B is the only unlined landfill cell and VOCs have typically been concentrated near it; the VOCs measured are typically erratic, low concentrations, characteristic of fluctuating • landfill gas conditions;the detected VOCs are typical of landfill gas constituents, VOCs have been detected in upgradient and downgradient wells; and generally there is an absence of notable inorganic constituents that would be associated with a liquid release. The most prevalent chemicals of concern that affect groundwater quality at typical landfill sites are chlorinated solvents (referred to as VOCs), common to hundreds of consumer products. The • origin of the VOCs in landfills is likely the result of a long process of degradation of household hazardous waste, containing common solvents such as tetrachloroethene (PCE), and • trichloroethene (TCE). The VOCs can be retained in solid state media (by adhering to clay particles as they move down in the unsaturated zone), in soluble form (as a dissolved fraction in • surface water or groundwater), or in the form of a gas (circulating in the flux of the other common landfill gases, methane and carbon dioxide). The VOCs can transform easily from the • solid, soluble, or gas form depending on the circumstances. • As part of the southern FU-19 expansion project,Forward Landfill requested the closure of wells that would be impacted in the footprint of that area (Lewis Engineering 2017). RWQCB • staff reviewed the January 23, 2018 Request for Relocation and Abandonment of MW-17, MW- 18, MW-19 (Republic Services 2017). The request included a groundwater monitoring well installation workplan that proposed to install replacement groundwater monitoring wells MW- 17R and MW-19R prior to properly destroying groundwater monitoring wells MW-17,MW-18, • and MW-19. Monitoring wells MW-17,MW-18, MW-19 would remain in place and continue to be sampled • until 30 days before construction of the new WMU, which is anticipated to occur in the spring . of 2019. The Request was approved by the RWQCB in their March 23, 2018 letter, stipulating • that the monitoring wells should be installed, developed, and sampled no later than the 3rd • Quarter of 2018. The Monitoring Well Installation Report should be submitted within 45 days of completing the wells. Once installed, the wells would be sampled in accordance with • Monitoring and Reporting Program R5-2014-0006. All data would be included in the quarterly • monitoring reports. A minimum of eight independent sampling events for monitoring wells • MW-17R and MW-19R are required by the RWQCB to build a statistical valid data set necessary for developing the Water Quality Protection Standard for FU-19. Accelerating the collection of • the data interval (more frequently than the normal quarterly monitoring) was permitted. • Forward is proposing to relocate MW-17 approximately 575 feet further west to be outside the • western limit of WMU FU-19 and rename this well MW-17R. MW-19 is planned to be relocated • approximately 180 feet east to be outside the eastern limit of WMU FU-19, and the well renamed MW-19R.As there are existing WNIUs to the north and south of WMU FU-19 and • • • •