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ameO I sopropyl benzene, naphthalene, n-propylbenzene, and sec-butyl benzene were detected in the groundwater sample collected from boring G-68-OU3 at concentrations of 100, 39, 96, and 25 micrograms per liter(Ng/L), respectively. Polynuclear aromatic hydrocarbons (PAHs)were detected at low concentrations in soil samples collected along the southern boundary of the Rail Yard by AMEC in 2009. With the exception of butylbenzylphthalate at one location, semi-volatile organic compounds were not detected in the samples collected in 2005 and 2006. Low concentrations of certain PAHs were detected in groundwater samples collected by AMEC from TRY-3/313, TRY-6, TRY-7/76, TRY-14/1413, and TRY-18. 2.3.2 Off Site South Area ARCADIS advanced four CPT borings (CPT-10, CPT-11, CPT,21, and CPT-22) in the Off Site South area west of Central Avenue for the collection of groundwater samples. These borings were located on the Tracy Rail Yard property, but south of the area previously defined as the Tracy Rail Yard site. TPH quantified as diesel (TPHd)were detected in groundwater samples collected from all four borings at concentrations of 74 (CPT-10), 210 (CPT-21), 77,000 (CPT-11), and 520,000(CPT-22) pg/L. TPH quantified as gasoline (TPHg) and TPH quantified as motor oil (TPHmo)were also detected in groundwater samples collected from borings CPT-11 and CPT-22. TPHg was detected at concentrations of 1,200 and 1,500 pg/L in CPT-11 and CPT-22, respectively. TPHmo was detected at concentrations of 74,000 and 650,000 pg/L in CPT-11 and CPT-22, respectively. CPT-22, which contained concentrations indicative of separate phase product, is located in the vicinity of the historical pipeline. No soil samples were collected in the Off Site South Area. 3.0 SAMPLING PLAN The objective of the proposed investigation is to: • delineate the extent of affected soil and groundwater previously identified along the southern boundary of the Tracy Rail Yard site east of Central Avenue (e.g., borings TRY-7, TRY-10, and TRY-11), and • assess the presence of affected soil and delineate the extent of previously- identified affected groundwater on the Rail Yard property south of the area previously defined as the Rail Yard site(west of Central Avenue; e.g., borings CPT-11 and CPT-22). To meet this objective, AMEC proposes to advance 10 borings(South-1 to South-10)for the collection of soil and groundwater samples. Additional locations may be added if further soil and/or groundwater sampling is required for lateral delineation of impacted soil or AMEC Geomatrix, Inc. K\16000s\161140\4000 REG ULATORY\South WP 063011\1 txt,cvrs,Itrs\Text.docx 4