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Mr. Jim Barton RWQCB March 29, 2013 Page 3 were reported from boring B-7 (TPHg at 2,300 micrograms per liter [µg/L] and TPHd at 5,300,000 µg/L): In September 2012, URS advanced five borings using direct push technology (B-36 through B-39, and B-41) to further characterize petroleum impacts in the areas of boring B-7. Four Shallow Borings (B-36 through B-39) Four shallow borings (B-36 through B-39) were advanced in the area surrounding boring B-7 to characterize the lateral extent of impacts reported during the 2005 investigation., Borings were drilled to first encountered-groundwater or approximately 20 to 24 feet bgs, and groundwater grab samples were collected from each boring. Groundwater samples and one soil sample from each boring were analyzed for TPHg, TPHd, and volatile organic compounds (VOCs). One Deep Boring(B-41) One deep boring (B-41) was advanced in the immediate vicinity of former Boring B-7 to a total depth of approximately 57 feet.bgs. Groundwater.grab samples were collected from the approximate depths of 15 feet, 45 feet, and 57 feet bgs to assess the vertical extent of TPHd impacts previously reported at this location .in 2005. Groundwater samples and one soil sample were analyzed for TPHg, TPHd, and VOCs. The groundwater sample collected from 15 feet bgs was also analyzed for nitrate, sulfate, sulfide, manganese, iron, and total dissolved solids to aid in the evaluation of future remedial options for the site, should that become necessary. Analytical Results. The soil sample collected from Boring B-41 had concentrations of TPHd at 40 mg/kg.No other soil samples from the borings in the vicinity of boring B-7 had concentrations of any of the constituents of concern above laboratory detection limits. Groundwater samples from this area had'concentrations of TPHg (up to 990 µg/L) in two borings and TPHd (up to 350,000 pg/L) in four borings, with the highest-concentrations found in sample B-41-15W(taken from boring B-41 at 15 feet bgs). Groundwater concentrations decreased significantly both laterally and vertically away from this sample location. Boring B-36, approximately 100 feet northwest of boring B- 41, did not report detectable concentrations of TPHg or TPHd .at first groundwater. Boring B-37, approximately 100 feet northeast of Boring B-41, reported only TPHd at 130 µg/L at first groundwater.. Boring B-38, approximately 80 feet southwest of Boring B-41, reported only TPHd at 130 µg/L at first groundwater. Boring B-39, drilled at the property boundary with the Union Pacific Railroad (UPRR) approximately 100 feet southeast of Boring B-41,reported TPHg at 430 µg/L and TPHd at 63,000 µg/L.