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LIGHT, AIR & SPACE CONSTRUCTION <br /> ENVIRONMENTAL SERVICES COMPANY <br /> State Contractor's License Number 445403 <br /> State EPA R.E_A.Number 04072 ' <br /> Office 408-979-0661 <br /> Highest Levels of Soil and Groundwater Contaminants Observed <br /> SOIL GROUNDWATER <br /> Contaminant Pre- Post Pre Excavation Post Excavation Monitoring Wells <br /> Excavation Excavation- <br /> Treatment Pad <br /> TPHG 690 M&jg ND ND NA 69 Ug/1 <br /> TPHD 28,000 M 72 M 5,200 U911 NA ND _ <br /> Benzene ND ND ND NA ND <br /> Toluene ND ND ND NA ND <br /> Eth ]benzene ND ND ND NA ND <br /> Xylenes 730 U ND ND NA ND <br /> MTBE ND ND ND NA 4 U <br /> ND—None detected NA—None analyzed. Mg/kg—Milligrams per kilogram. Ug/l—Micrograms per liter. <br /> The 2006 extremity soil sample data show that the TPHG and TPHD contaminants were <br /> removed by soil excavation and post excavation treatment pad soil samples indicated almost <br /> complete removal of contaminants(see Tables 4,5 and 6). <br /> The October 2008 groundwater monitoring well sampling data showed that TPHD was not <br /> detected, and only 69 Ug/1 TPHG and 3.99 Ug/l MTBE were present in 2008. The March 2009 <br /> second round of monitoring well sampling showed that neither TPHD or TPHG were detected <br /> and only MTBE was detected at 4.0 Ug/l was present,below the current MTBE MCL of 13 Ug/l. <br /> 9.0 Concentrations and Mass Changes- Groundwater <br /> Groundwater samples collected from the former UST pits showed a range of TPHD of 81 to <br /> 5,200 Ug/l in 2006. Groundwater wells installed in 2008 showed that TPHD was not detected in <br /> any well. Only 69 Ug/l TPHG was detected in MW-1 and, 3.99 Ug/1 MTBE in MW-3 in <br /> December 2008. A second set of well samples in March 2009 showed no detection of TPHG or <br /> TPHD and 4.0 Ug/l MTBE in Well MW-3 (see Figures 4, 5, 6 and 7). BTEX and fuel <br /> oxygenates ETBE,TAME,DIPS,TBA, 1,2-DCA and EDB were not detected in any well. <br /> This is interpreted as a very small residual dissolved fuel plume given the lack of any other <br /> detections on TPHG or TPHD. The dissolved contaminant mass of TPHG and TPHD has <br /> decreased to essentially zero. The MTBE detections are below the current MCL and occur in the <br /> downgradient well. It is our opinion that natural degradation processes have operated on the <br /> residual fuel contaminants and will continue to degrade the remaining MTBE. <br /> Page 7 of 16 <br /> MAIN OFFICE • 1707 LITTLE ORCHARD STREET,SUITE A •SAN JOSE•CA•95125 <br /> MAILING ADDRESS•P.O.Box 36303•SAN JOSE.CA•95158.6303•4081979-0661-4081979-0621 FAX-LASCONSTQAOL.COM E-MAIL <br /> GENERAL AND ENGINEERING CONTRACTOR-HAZARDOUS SUBSTANCE REMOVAL CONTRACTOR-SiTE ENVIRONMENTAL ASSESSMENTS <br /> WETLAND AND RIPARIAN HABITAT—ASSESSMENT-DESIGN—RESTORATION—CONSTRUCTION—MITIGATION MONITORING <br />