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ERI 227903 R02 Former Unocal Service Station 5098,Stockton,California July 30, 1999
<br /> FIELD WORK
<br /> ScQW of Work
<br /> ERI obtained an encroachment permit from the City to drill in a City of Stockton right-of-way, and
<br /> obtained a permit from the County to drill the borings and install groundwater monitoring wells
<br /> Copies of the permits are provided in Attachment B ERI performed the field work in accordance with
<br />' ERI's Work Plan and Addendum, a site-specific Health and Safety Plan which was kept on site during
<br /> field operations, and ERI's field protocol {Attachment C)
<br />' Soil Borings and Monitoring-Well InAgUation
<br /> On January 25 through February 2, 1999, ERI observed Woodward Drilling Company, Inc
<br /> 1 (Woodward) of Rio Vista, California, drill seven 8-inch soil borings (Bl, B2, MW10A, MW14A,
<br /> MW 18, MW 195, and MW 19D) The soil borings were advanced to depths ranging from approximately
<br /> 50 to 81 5 feet bgs During the field work, ERI discovered that the remaining monitoring wells
<br /> (MW21S, MW21D, MW22S, and MW22D) could not be installed in their proposed locations due to
<br /> conflicts with underground utilities The proposed locations of the wells were moved onto the adjacent
<br /> Firestone Tire property located at 5545 Pacific Avenue in Stockton,California The project was delayed
<br /> while Unocal acquired an access agreement with Bridgestone/Firestone, Inc ERI and Woodward
<br /> returned to the site on May 18 though 21, 1999, to drill five 8-inch soil borings (MW21S, MW21D,
<br /> MW22S, MW22D, and HPI) The soil borings were advanced to depths ranging from 49 to 66 feet bgs
<br /> Drilling was performed under the guidance of an ERI geologist who collected soil samples from the
<br /> borings during drilling Soil samples were collected at approximately 5-foot intervals in borings Soil
<br /> samples were not collected from shallow borings MW 195, MW21S, or MW22S, due to the proximity
<br /> of the corresponding deep borings Three discrete grab groundwater samples were collected from
<br /> depths of approximately 34, 45, and 63 feet bgs in boring HP1, utilizing Hydropuncho technology
<br /> ERI's geologist described the soil lithology of the soil samples collected from the bonngs using visual
<br /> and manual classification methods The samples were classified using the Unified Soil Classification
<br /> System (Attachment D) Descriptions of the materials encountered are presented in the Boring Logs
<br /> (Attachment D)
<br /> Soil cuttings generated during each drilling event were stockpiled in a storage bin and covered with
<br /> plastic sheeting Stockpiled soil from the first and second drilling events were temporarily stored on the
<br /> subject site and on the K-Mart property, located at 5757 Pacific Avenue, Stockton, California,
<br /> respectively,pending appropriate disposal by Unocal ERI collected one composite soil sample (four
<br /> brass sleeves per composite) from stockpiled drill cuttings during each drilling event for laboratory
<br /> 1 analyses
<br /> Monitoring Well Construction, Development, Surveying, and Sampling
<br /> Woodward constructed monitoring wells MW10A, MW14A, MW18, MW19S, MW19D, MW21S,
<br /> MW21D, MW22S, and MW22D, in the respective borings Soil borings B1 and B2 were drilled
<br /> exclusively for the collection of soil samples Details of monitoring well construction are shown on the
<br /> Boring Logs (Attachment D)
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