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Brownfields Site Assessment June 2014 South Gifford Road Landfill, Vero Beach,Florida 3. ASSESSMENT METHODOLOGIES 3.1 Overview Our understanding of conditions and potential exposure pathways that may impact health and safety of the community guided development of the assessment activities described herein. These exposure pathways included: • Surface soils—it is important to evaluate the thickness of the landfill cover soils to ensure sufficient cover to prevent direct exposure to the waste. It is also important to evaluate the chemical compositions of the soil cover to verify that the cover soils are"clean". • Landfill Gas — waste materials decompose as they age and typically generate methane. Methane can be an explosion hazard under certain conditions. For an explosive condition to exist, landfill gas must accumulate in a confined space. If buildings or other potential confined spaces are a part of the development plan, a properly designed and constructed control system should be in place to minimize potential hazards. • Groundwater — groundwater is being investigated, remediated, and monitored separate from this assessment under the purview and with oversight from the FDEP. Much of the groundwater has been cleaned up; however, there are residual levels of certain contaminants above cleanup target levels. Limiting groundwater use until it is cleaned up to levels that allow unrestricted use will minimize potential exposure to contamination in the groundwater. The sampling strategy was designed to screen for potential constituents of concern (CDCs) typical of sites with similar historical uses, including: semi-volatile organic compounds (SVOCs); Resource Conservation Recovery Act (RCRA) metals; VOCs; organochlorinated pesticides (OCPs); organophosphorous pesticides (OPP); and herbicides. The assessment area and sampling locations completed as part of the activities described herein are shown on Figure 4. Soil and soil gas samples were collected pursuant to the EPA Region 4-approved Site- Specific Quality Assurance Project Plan (QAPP). Field forms are included in Appendix A. 3.2 Soil Sampling The soil sampling methodology was designed to characterize surface soils from the ground surface to 2 ft BLS. Soil samples were collected on an approximate 225 ft-spaced grid (between points) from 29 locations using a decontaminated hand auger (locations provided on Figure 4). Prior to mobilizing, Sunshine State One Call of Florida, Inc. was notified of the proposed subsurface activities to locate utilities in the vicinity of proposed soil boring locations. Two soil samples were collected at each soil boring location at depth intervals of 0 to 0.5 and 0.5 to 2 ft FR0766H 6 7/8/2014