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- , Ardaman & Associates, Inc. November 25, 2014 Ardaman File No. 13-5402 Revised February 2, 2015 Geotechnical, Environmental and Materials Consultants Indian River County EXHIBITA Engineering Division 1801 271t' Street Vero Beach, Florida 32960-3388 Attention: Mr. Michael Nixon, P.E. Subject: Proposal for Level 3 Contamination Assessment Intersection of State Road 60 (201 Street) and 43rd Avenue Indian River County, Florida Mr. Nixon: As requested, Ardaman & Associates, Inc. (Ardaman) has prepared a scope of work and estimation of costs related to performing additional contamination assessment for possible soil and groundwater subsurface contamination at the above referenced site. This proposal includes soil and groundwater sampling and testing to explore for the presence of soil and/or groundwater contamination along areas of the project site relative to the Contamination Review Memo prepared by FDOT and dated August 12, 2014. BACKGROUND INFORMATION Indian River County plans to improve the intersection of State Road 60 (20th Street) and 43`d Avenue in Indian River County, Florida. The proposed improvements include widening of the roadways from the existing four -lane to provide for a six -lane divided roadway with median, curb and gutter on the median side and resurfacing of the existing pavement. Arcadis completed a Contamination Screening Evaluation Report (CSER) for the project study area in February 2007. The project study area extends up to the existing bridge over the Main Relief Canal to the north and west and for approximately 2,200 feet to the south and east from the intersection. The purpose of the CSER was to identify and evaluate sites with known or potential for contamination within the project study area. Twelve sites were identified in the CSER as having "medium" and "high" potential for contamination. The project study area was later reduced to include nine sites with "high" and "medium" potential for contamination. In 2013, Ardaman performed a limited soil and groundwater assessment in the right-of-way expansion areas adjacent to sites ranked as "high" and "medium". Please refer to our Level II Contamination Assessment report dated January 8, 2014 for details of our findings. Soil analytical results did not indicate the presence of soil contamination at levels above the residential or commercial soil cleanup target levels (SCTLs) at the sampling locations. However, low levels of contaminants were found at seven of the locations which indicate that higher concentrations could be found nearby. Based on the depth to groundwater encountered during the field work to -date and on the anticipated depths of proposed utility structure installations, dewatering during construction will likely be needed. Given that groundwater contaminants were detected at twelve sampling locations and since many of the source sites have historic documentation of contamination IL plumes that have migrated offsite, additional groundwater sampling and testing was recommended by FDOT. 37