FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Mr.M. Scott Mansholt—CEMC First Quarter 2007 Groundwater Monitoring and Sampling Report April 24,2007 US Can-Welty Road Page 5 of 6 QUARTERLY OLEOPHILIC SOCK REPLACEMENT An oleophilic sock was installed in well MW-1 due to the presence of SPO in the well, and an oleophilic sock was placed in MW-2 due to the petroleum odor detected from the well. The socks in MW-1 and MW-2 have been monitored and replaced as necessary on a quarterly basis. During the recent monitoring event,the oleophilic sock from MW-1 was replaced and approximately 4 ounces (0.03 gallon) of SPO was absorbed. The oleophilic sock from MW2 was not replaced due to the lack of SPO. A total of approximately 0.34 gallon of SPO has been removed since June 1999. A summary of SPO thickness measurements is included in Table 1. QUALITY ASSURANCE/QUALITY CONTROL All field procedures were conducted in accordance with SAIC's Quality Assurance and Quality Control Sample Collection, Handling, and Analysis6 procedures. Based on SAIC's evaluation, all analytical data are usable as qualified for the purpose of determining chemical concentrations in groundwater at the site. Qualified data with applicable reason codes are shown in Table B-1 of Attachment B. Unless noted otherwise,analytical data collected in support of this investigation are considered precise, accurate,representative,complete, and comparable, and they may be used for their intended purposes. CONCLUSIONS AND RECOMMENDATIONS The groundwater elevation varied between 71.26 and 71.60 feet above MSL with a gradient toward the east at 0.001 ft/ft. PAH concentrations remained stable and low. SPO has been observed in wells MW-I and MW-2 since 1999. Oleophilic socks in wells MW-1 and MW-2 will be monitored quarterly and replaced as necessary The dissolved-phase TPHd appear to be stable and not migrating, except in the vicinity of off-site well WFSMW-1. Samples from well WFSMW-1 continue to show elevated levels of TPHd. Results from the fuel-fingerprint analysis show that dissolved gasoline is present in the water samples from WFSMW-1 and heavier-end,gasoline-range hydrocarbons may be giving the appearance of increasing TPHd concentrations. SAIC recommends terminating all monitoring and sampling at the site except for collecting one additional split sample from WFSMW-1. The field sample will be split for analysis and submitted to Lancaster Laboratories and ETC to confirm the presence of gasoline-range hydrocarbons and the lack of diesel-range hydrocarbons. SAIC is preparing a work plan to properly destroy wells MW-3 and MW-4 because the water volumes in these wells are insufficient for adequate sample collection. In addition, SAIC proposes to advance seven soil borings constructed of temporary,pre-packed well screens and collect soil groundwater samples to further define the extent of petroleum hydrocarbons in the soil and groundwater at the site. The work plan for additional site characterization and well destruction will be submitted during the second quarter of 2007. 6. SAIC,2007. Quality Assurance and Quality Control Sample Collection,Handling,and Analysis. April (Update).