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l7 <br />+i <br />GF.oSYNTT•c ComulTANTS <br />Mr. Ronald Brooks <br />10 2 March 2040 <br />Page 3 <br />+ one soil sample will be collected from each boring using Encore samplers and <br />will be analyzed for volatile organic compounds by EPA Method 8260; and <br />one groundwater sample will be collected from each boring and will be <br />analyzed for purgeable halocarbons and aromatics by EPA Method 8021. <br />Additional details regarding the sampling methodologies, screening intervals, <br />boring locations, etc. are provided within Section 5.2 of the PRAP and in the response <br />letter. The results of the source assessment will be summarized in a technical <br />memorandum. This memorandum will be submitted to FDEP through Indian River <br />County. <br />Trask 3. Initial Site Screening for hfNA <br />Under Task 3, an initial site screening for monitored natural attenuation (MNA) <br />will be conducted in accordance with Sections 5.3.1 through 5.3.2 of the PRAP. Site <br />screening for natural attenuation parameters will include sampling of: (i) 15 scicctcd <br />existing monitoring wells (as shown in figure 5-2 of the PRAP, with the addition of <br />monitoring wells GR -MW -05B and GR -MW -05C per FDEP's request); and (ii) one <br />additional monitoring well to be constricted (GR -MW -1363). During field activities, as <br />baseline evaluation of naturally occurring biodegradation parameters will be performed. <br />As part of this evaluation, the following field measurements will be obtained from each <br />of the 16 wells just prior to sampling: pl1, dissolved oxygen (DO), redox potential, <br />turbidity, temperature, and specific conductance. The selected wells will then be <br />sampled and analyzed for chlorinated VOCs and common indicators of reductive <br />dechlorination processes, including-, electron acceptors (nitrate and sttlfatc); electron <br />donors (sulfide, ferrous iron, and dissolved organic carbon); degradation reaction <br />products (chloride, ethenc, ethane, and inethanc); and alkalinity. When available, IPA <br />methods will be used to analyze for the natural attenuation ntonitoring paranrcters <br />presented in 'fable 5-2 of the PRAP. Results from natural attenuation parameter <br />sampling will be used to assess biodegradation pathways and processes. If the initial <br />site screening indicates that a significant level of natural attenuation is occurring, then a <br />XR991701R000067.doc <br />