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In Parcel 24 and Parcel 3, seven (7) boreholes (Boreholes B-3/MW-3, B-7/MW-7, 3MW-1/1R,
<br />MW-36, DP-8, DP-9, DP-21) have been advanced from which four (4) (Boreholes B-3/MW-3, B-
<br />7/MW-7, 3MW-1/1R, MW-36) were converted into groundwater monitoring wells. The
<br />remaining three (3) boreholes (Boreholes DP-8, DP-9, and DP-21) were sampled both for soil and
<br />groundwater but not converted into wells. Soil sample data could not be located for Wells 3MW-
<br />1/1R or MW-36. Well 3MW-1R is a replacement for Well MW-1, which was installed in 1999
<br />but subsequently destroyed. In addition, two (2) of the monitoring wells (Wells 3MW-1R and
<br />MW-36) were abandoned on 5 April 2004.
<br />In Parcel 24, soil samples were collected during the installation of Wells MW-3 and MW-7.2
<br />Laboratory analytical results indicated that the soil samples collected at depths of 20 feet and 15
<br />feet, respectively, did not contain gasoline or diesel petroleum hydrocarbons above method
<br />detection limits (MDLs). Additionally, benzene was not detected above the reported MDLs.
<br />Other chemicals of concern (COCs) such as VOCs, fuel oxygenates (methyl-t-butyl-ether
<br />[MTBE], tert-butyl-alcohol [TBA]), and metals including arsenic (As) and lead (Pb) were not
<br />analyzed.
<br />In Parcel 3, soil samples collected from Boreholes DP-8, DP-9 and DP-21 identified TPHd
<br />and TPHo, and the metals As and Pb.3
<br />The metals As and Pb in Borehole DP-8 were identified at depths of one (1), three
<br />(3), and five (5) feet, with concentrations of 2.6 mg/kg, 3.2 mg/kg and 6.5 mg/kg for
<br />As, and 40 mg/kg, 20 mg/kg and 200 mg/kg for Pb, respectively. These metals were
<br />also identified in Borehole DP-9 at depths of one (1), three (3), and five (5) feet, with
<br />concentrations of 1.9 mg/kg, 2.4 mg/kg and 2.9 mg/kg for As, and 110 mg/kg, 280
<br />mg/kg and 8.5 mg/kg for Pb, respectively.
<br />Total petroleum hydrocarbons as gasoline (TPHg), TPHd or TPHo, and VOCs were
<br />not detected above their reported MDLs, and fuel oxygenates were not analyzed for
<br />in these samples. TPHd was detected in Borehole DP-21 at a depth of five (5) feet,
<br />and a concentration of 4.1 mg/kg, and at depths of five (5) and 34 feet, with
<br />concentrations of 7.8 mg/kg and 5.0 mg/kg, respectively.
<br />Other COCs such as benzene and other VOCs, and fuel oxygenates (MTBE, TBA)
<br />were not analyzed.
<br />Soil samples collected by Treadwell & Rollo (1999 and 2001) identified TPHd and metals
<br />(including Pb and Hg) in soil.
<br />TPHd was detected at 18 mg/kg at five (5) feet bgs, in Well 3MW-1.
<br />Total Pb concentrations ranged from six (6) to 710 mg/kg, soluble lead using the
<br />California Soluble Threshold Limit Concentration (STLC) method ranged from 0.38
<br />to 24 milligrams per liter (mg/L). Soluble Pb using the U.S. Environmental
<br />2 Applied GeoSystems, 1989 and 1991
<br />3 Clayton Group Services, 2002, Appendix A, December 23"
<br />Golden State Environmental, Inc. - 6 - Los Angeles, San Diego and Houston
<br />Revised Work Plan — Soil and GW Characterization July 2006
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