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Former Vernalis Pump Station -5 - 19 March 2004
<br /> Bellini and Arcos Properties
<br /> San Joaquin and Stanislaus Counties
<br /> the former pump house, boiler house, heater house, rubbish pits, sumps, bulk storage tanks, and/or former
<br /> pipelines.
<br /> The former structures, except for a few concrete foundations, have been removed from the site. The site
<br /> is now used for storage of trailers, construction equipment, miscellaneous debris, and there is an onsite
<br /> office trailer and a private residence. One domestic water well is located approximately 75 feet east of
<br /> the former heater house. Construction records or pertinent information was not available for the well.
<br /> Reportedly, water from the well is used primarily at the office and not for domestic consumption.
<br /> Soil
<br /> Soil borings, ranging from 40 to 55 feet deep were advanced at twelve different locations. Shallow soil -
<br /> samples were obtained from most of the borings at 1, 5. and/or 10 feet. The 1 and 5 foot samples (none �
<br /> visually affected) were analyzed for PAHs and the 10 foot and deeper samples were submitted for TPH-c, f£
<br /> BTEX, and PAH analysis. Samples were collected from intervals of the most visually impacted soil, first
<br /> groundwater and at the bottom of each boring where affected soil was not observed.
<br /> Impacted soil was present in three borings (ASB-1, 2, and 4) from 7 feet to at least 40 feet, with TPH-c
<br /> detected at intervals coinciding with visually impacted soils. TPH-c was detected in ASB-1 (43.5 feet),
<br /> ASB-2 (29 feet) and ASB-4 (40 feet), at 55, 17,000, and 14,000 mg/kg, respectively. TPH-c was not
<br /> detected in the other nine borings. Benzene at 0.95 mg/kg was reported in one sample at 29 feet in
<br /> ASB-2. Toluene, ethylbenzene and xylene constituents were detected at low concentrations in three
<br /> samples- 29 feet, 10.5 feet, and I foot,in borings ASB-1, 4, and 10, respectively.
<br /> t
<br /> PAH compounds were detected at various depths in samples from ASB-1 (1 and 43.5 feet), ASB-2 (1 and
<br /> 29 feet), ASB-4 (5, 10.5, and 40 feet), and ASB-7 (1 foot). Generally, the PAH concentrations were less
<br /> than 1 mg/kg. Higher concentrations of PAHs present at 10.5 to 40 feet in ASB-2 and ASB-4, also
<br /> contained elevated TPH-c concentrations.
<br /> Shallow soil samples (1, 5, and 10 feet) were collected and submitted for Title 22 metals analysis. One of
<br /> the samples, obtained from ASB-7 on a portion of the site not directly associated with former pump
<br /> station activities, was used for comparison purposes as representative background metals values. The
<br /> results for the other samples were comparable or less than the values reported for ASB-7. Various metals
<br /> P
<br /> were detected in the samples, but none were considered hazardous and all were less than the US EPA
<br /> PRGs for residential and/or industrial soils.
<br /> According to the field observations and analytical results, the extent of impacted soil has not been
<br /> adequately delineated on the Arcos property.
<br /> Groundwater
<br /> Depth to first unconfined groundwater during the August and October 2003 investigation was
<br /> approximately 32 to 37 feet, similar to the Bellini property to the north, and flow direction is generally
<br /> east-northeast. Eight grab groundwater samples were collected for analysis. TPH-d was detected in five
<br /> of the samples at concentrations ranging from 110 to 2,900 µg/L, some of which coincide with borings
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