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1 <br /> ElhRit® <br /> W.Margaret Lagorio <br /> ' July 19, 2004 <br /> Page 4 <br /> ' groundwater samples were submitted for analyses of BTEX by EPA Method 8021 and TPHg by <br /> EPA Method 8015 Modified. Laboratory analytical results with chain-of-custody documentation <br /> are included as Attachment C. Graphs of concentrations of TPHg and benzene versus time in <br /> ' wells U-3 and U-10 and piezometers NP-1 and NP-2 are included as Attachment D. There is no <br /> change in the graphs for NP-1-22, NP-1-65, NP-1-111 or NP-2-116 as they were not sampled this <br /> quarter. <br /> ' Discussion <br /> During March 2004, new tubing, valves and fittings were installed on the existing system. Since <br /> ' that time, concentrations of petroleum hydrocarbons in groundwater decreased overall near <br /> wells U-3, U-10, and NP-2-22. The concentrations around these wells and NP-1 have <br /> continued to decrease. Petroleum hydrocarbon concentrations in well U-3 significantly <br /> ' decreased during the 2nd quarter 2004 event; TPHg decreased from 19,000 micrograms per liter <br /> (pg/L) to 2,500 pg/L. <br /> ' Recommendations <br /> ENSR recommends that operation of the Ozone Pilot Test continue and further groundwater <br /> sampling and D.O. monitoring be performed to evaluate the system's effectiveness. <br /> Future Work <br /> ' The third quarter groundwater monitoring and sampling is currently scheduled for August 2004. <br /> 1 <br /> 1 <br /> ' - J:1Projects10694010187-3251FinaAReportsQnd Qtr 04-QMR RSR10187 2nd Qtr 04-QMR RSR.doc <br /> Over 30 Years of Excellence in Environmental Services <br />