FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Report for Monitor WelP%jwf6ling and Groundwater Investigation Pilkington North America July 23,2003 Page 6 SUMMARY AND RECOMMENDATIONS On July 2, 2003, Condor conducted fieldwork at the site of a 1997 UST removal. Four borings were installed around the location of the former UST to collect one soil and one groundwater sample per boring. Field observations made during the installation of the borings did not indicate the presence of petroleum hydrocarbons. Laboratory analytical results of the soil and groundwater samples indicate that gasoline constituents were not present at or above laboratory reporting limits. Based on the results of the current and historical data, Condor recommends, on behalf of PNA, site closure. On July 9, 2003, Condor conducted monitor well surveying, water level measurements, and sampling at the site of the 1986 and 1987 UST removals. The resulting groundwater elevation measurement data indicate that the groundwater gradient was southwest at 0.0037 foot/foot on July 9, 2003.The direction of groundwater flow on that date indicates that monitor wells MW-17 and MW-18 were down to cross- gradient of the UST source area. Field observations during the monitor well sampling activities did not indicate the presence of petroleum hydrocarbons. Laboratory analytical results of the groundwater samples indicate that gasoline constituents were not present at or above the laboratory reporting limits. Historical data collected by WCC for the 1986/1987 UST removal site indicate that relatively low concentrations of petroleum hydrocarbons were present in site soil and groundwater during the time that the investigation was conducted. Subsequent WCC data and the results of the current work indicate that there is no groundwater impact in the location of MW-17 and MW-18 at or above laboratory reporting limits. Current groundwater flow data and groundwater flow data associated with other groundwater investigation activities in the vicinity indicate that the groundwater gradient at the site may vary from southeast to southwest, probably as a result of groundwater extraction both at the facility and off-site. It is Condor's opinion that samples collected from MW-17 and MW-18 would indicate some impact from the source area if a substantial impact were present at the site. However, because the current data do not indicate an impact at MW-17 and MW-18 at or above laboratory reporting limits, Condor recommends, on behalf of PNA, that the site be considered for closure. If you have any questions or need additional information,please call us at(209)234-0518. Respectfully submitted, CONDOR EARTH TECHNOLOG S,INC. ID Donald F. Kresse No.6430 1 Lee H. Morse California Registered q Associate Geologist Geologist#6430 �Of CA��4©� Attachments: A (Figures 1 through 5), B (Boring Logs and Sampling Forms), and C (Laboratory Analytical Reports) cc: Mr. Roger Bishop,Pilkington North America P:\3151 Pilkinton PLOF\3151J UST Review\Reports\Reports\3151 MWSamplingGeoprobe Rpt doc ow W CONDOR