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ElIF ® Ardaman & Associates, Inc. <br />MAUGeotechnical, Environmental and <br />Materials Consultants <br />Indian River County <br />Engineering Division <br />1801 27th Street <br />Vero Beach, Florida 32960-3388 <br />Attention: Mr. Michael Nixon, P.E. <br />November 25, 2014 <br />Ardaman File No. 13-5402 <br />Revised February 2, 2015 <br />EKWIE. 07 A <br />Subject: Proposal for Level 3 Contamination Assessment <br />Intersection of State Road 60 (20th Street) and 43rd Avenue <br />Indian River County, Florida <br />Mr. Nixon. <br />As requested, Ardaman & Associates, Inc. (Ardaman) has prepared a scope of work and <br />estimation of costs related to performing additional contamination assessment for possible soil <br />and groundwater subsurface contamination at the above referenced site. This proposal includes <br />soil and groundwater sampling and testing to explore for the presence of soil and/or groundwater <br />contamination along areas of the project site relative to the Contamination Review Memo <br />prepared by FDOT and dated August 12, 2014. <br />BACKGROUND INFORMATION <br />Indian River County plans to improve the intersection of State Road 60 (20th Street) and 43rd <br />Avenue in Indian River County, Florida. The proposed improvements include widening of the <br />roadways from the existing four -lane to provide for a six -lane divided roadway with median, curb <br />and gutter on the median side and resurfacing of the existing pavement. Arcadis completed a <br />Contamination Screening Evaluation Report (CSER) for the project study area in February 2007. <br />The project study area extends up to the existing bridge over the Main Relief Canal to the north <br />and west and for approximately 2,200 feet to the south and east from the intersection. The <br />purpose of the CSER was to identify and evaluate sites with known or potential for contamination <br />within the project study area. Twelve sites were identified in the CSER as having "medium" and <br />"high" potential for contamination. The project study area was later reduced to include nine sites <br />with "high" and "medium" potential for contamination. <br />In 2013, Ardaman performed a limited soil and groundwater assessment in the right-of-way <br />expansion areas adjacent to sites ranked as "high" and "medium". Please refer to our Level 11 <br />Contamination Assessment report dated January 8, 2014 for details of our findings Soil <br />analytical results did not indicate the presence of soil contamination at levels above the residential <br />or commercial soil cleanup target levels (SCTLs) at the sampling locations. However, low levels <br />of contaminants were found at seven of the locations which indicate that higher concentrations <br />could be found nearby. <br />Based on the depth to groundwater encountered during the field work to -date and on the <br />anticipated depths of proposed utility structure installations, dewatering during construction will <br />likely be needed. Given that groundwater contaminants were detected at twelve sampling <br />locations and since many of the source sites have historic documentation of contamination <br />plumes that have migrated offsite, additional groundwater sampling and testing was <br />recommended by FDOT. <br />