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Monitoring Well Installation Work Plan — March 2017 <br />SIERRA LUMBER CASE #2 <br />375 West HazeIton Avenue, Stockton, California <br />1.0. INTRODUCTION <br />At the request of Mr. Bob Long of Sierra Lumber Manufacturers, Advanced <br />GeoEnvironmental, Inc. (AGE) has prepared this Monitoring Well Installation Work Plan <br />for the property located at 375 West HazeIton Avenue, Stockton, California (site). A site <br />location map is included as Figure 1. Historical soil borings, UST locations and proposed <br />monitoring well locations are illustrated in Figure 2. The lateral and deep extent of <br />petroleum hydrocarbon impacted groundwater is illustrated in Figures 3 and 4, <br />respectively. Well construction details for existing monitoring and remediation wells are <br />summarized in Table 1. Historical soil and groundwater analytical data are included in <br />Tables 2, 3 and 4. <br />AGE previously performed additional on-site and off-site assessment in March 2015 and <br />in May 2016 by advancing five (5) soil borings (B8, B9, B10, B11 and B12) to depths of <br />145 feet bsg. Results of the investigation detected gasoline impact (i.e. benzene) in grab <br />groundwater samples collected from borings B8, B10, B11 and B12. Due to the <br />groundwater impact encountered at B8, B10, B11 and B12, the Central Valley Regional <br />Water Quality Control Board (RWQCB) directed by letter dated 23 February 2017 <br />(Appendix A) that groundwater monitoring wells were needed to confirm previous grab <br />groundwater sample results from soil borings, to establish groundwater trends and to <br />evaluate the stability of the plume. <br />This work plan has been prepared in accordance with guidelines established by RWQCB <br />for the subsurface investigation of UST sites. This monitoring well installation work plan <br />details procedures for the installation of one deep groundwater monitoring well to <br />potentially fully assess hydrocarbon impact from leaking underground storage tanks <br />(USTs) previously located at the site. <br />2.0. SCOPE OF WORK <br />The scope of the work includes the drilling and installation of one (1) deep-screened <br />groundwater monitoring well at depths between 120 and 130 feet below surface grade <br />(bsg). The proposed well will assess the southward extent of deep groundwater <br />hydrocarbon impact resulting from leaking UST's. The scope of work will include the <br />following tasks: <br />Permitting and pre-field work activities; <br />Pilot drilling and soil sample collection; <br />Monitoring well installation and development;