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Monitoring Well Installation Work Plan — August 2017 NOMELLINI CONSTRUCTION CO. 1045 West Charter Way, Stockton, California 1.0. INTRODUCTION Advanced GeoEnvironmental, Inc. (AGE) has prepared this Monitoring Well Installation Work Plan for the site located at 1045 West Charter Way, Stockton, California (site). A site location map is included as Figure 1. Historical soil borings, UST locations and proposed monitoring well locations are illustrated in Figure 2. A proposed well construction monitoring well diagram is included with Figure 3. Historical soil and grab groundwater analytical data are included in Tables 1, 2, 3 and 4. Based on previous soil characteristics data obtained by cone penetrometer testing (CPT) and by soil boring/well drilling, AGE has defined three informal hydrogeologic units at the Nomellini Construction Company (NCC) site. The informal hydrogeologic units are being defined as First Water Zone (15 to 30 feet bsg), Second Water Zone (30 to 60 feet bsg), and Third Water Zone (95 to 115 feet bsg). A Site Assessment Work Plan (dated 20 March 2017) was previously submitted to the Central Valley Regional Water Quality Control Board (RWQCB) for drilling of three (3) soil borings located west (B-23), northwest (B-24) and north-northwest (B-25) of the site. All three soil borings were proposed to total depths of 100 feet below surface grade (bsg) for collection of First Zone, Second Zone and Third Zone grab groundwater samples. However, by letter dated 05 May 2017, the RWQCB directed groundwater monitoring wells should be installed rather than collection of grab samples in the proposed areas of B-23 and B-24. This work plan has been prepared in accordance with guidelines established by RWQCB for the subsurface investigation of UST sites, and is in response to the RWQCB letter, dated 05 May 2017 (Appendix A). 2.0. SCOPE OF WORK The scope of the work includes the drilling and installation of two (2) intermediate- screened groundwater monitoring wells at depths between 35 and 55 feet below surface grade (bsg). The proposed wells will assess off-site Second Water Zone groundwater hydrocarbon impact resulting from leaking UST's. The scope of work will include the following tasks: • Permitting and pre-field work activities; • Pilot drilling and soil sample collection, • Monitoring well installation and development; • Laboratory analysis of soil samples;