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<br /> CHECKLIST OF REQUIRED DATA FOR NO FURTHER ACTION REQUESTS AT
<br /> UNDERGROUND TANK SITES
<br /> Barnyard Site, 8960 W Walnut Grove Rd, Thornton, CA
<br /> Page 2
<br /> 10 Reports/information
<br /> URF--unknown date
<br /> QMRs--see Ground Zero Analysis, Inc Groundwater Monitoring and Sampling Reports
<br /> dated, October 15, 2001, February 11, 2001, May 15, 2002, August 8, 2002, October 23,
<br /> 2002, January 27, 2003 April 29, 2003, and August 8, 2003
<br /> Other reports-see Ground Zero Analysis, Inc Workplan for Conducting a Limited
<br /> Subsurface Assessment, November, 25, 1996, Limited Subsurface Assessment, January 23,
<br /> 1997, Workplan for Subsurface Investigation, June 29, 1999, Subsurface Investigation
<br /> Summary Report, October 19, 2999, Workplan Addendum for Interim Soil and Groundwater
<br /> Corrective Action, February 15, 2000, Workplan Addendum #2, March 14, 2000, Interim Soil
<br /> and Groundwater Corrective Action Summary Report, December 29, 2000, Addendum to
<br /> Interim Soil and Groundwater Corrective Action Summary Report, January 8, 2001,
<br /> Groundwater Monitoring Well Installation Report, August 9, 2001, Workplan for Additional
<br /> Subsurface Investigation, August 8, 2002, Groundwater Monitoring Well Installation Report,
<br /> January 8, 2003
<br /> 11 Best available technology AT used Soil Excavation and aeration, groundwater extraction
<br /> and disposal and natural attenuation
<br /> 12 Reason why background was unattainable using BAT Soil was excavated to non-detect
<br /> except for one location (11 ppm TPHD) Groundwater concentrations reduced from 37,000
<br /> ppb MTBE to 100 ppb MTBE, and levels continue to decline Only two wells contain MTBE
<br /> above method detection limits (MW3 at 100 ppb, MW5 at 4 5 ppb)
<br /> 13 Mass balance of treated versus remaining contaminants Based on analytical results from soil
<br /> samples collected subsequent to excavation activities, no significant amount of soil
<br /> contamination remains It is estimated that approximately 450 cubic yards of contaminated
<br /> soil were removed from the UST pit excavation in January 1999, and approximately 2,650 cy
<br /> of contaminated soil and 1,100 cy of clean overburden were removed during interum remedial
<br /> activities in March 2000 Based upon the average concentrations detected in soil samples
<br /> collected before and after the excavation, we estimate that 7,931 pounds of gasoline, 5,731
<br /> pounds of diesel, 21 pounds of benzene, 45 pounds of toluene, 137 pounds of ethylbenzene,
<br /> 772 pounds of xylenes, and 95 5 pounds of MTBE were removed by soil excavation We
<br /> estimate that a maximum of 3 6 pounds of gasoline, 26 2 pounds of diesel, 0 12 pounds of
<br /> benzene, and 0 04 pounds of MTBE remains in the soil (Attachment D)
<br /> WFp -ckhst doc 2
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