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Remedial Action Plan June 14, 2017 Project#Z054000052 Page 7 3.0 PROPOSED SCOPE OF WORK ATC recommends the installation and operation of a proposed Soil Vapor Extraction System (SVE) to evacuate three existing Vapor Extraction Wells (VE-1, VE-2, and VE-3). Please refer to Figure 2. To maximize the effectiveness of this SVE system ATC recommends installing and operating a proposed Air Sparge System (AS) connected to seven air sparge wells. These seven wells consist of one existing shallow air sparge well (AS-1), three proposed shallow air sparge wells and three proposed deep air sparge wells (proposed wells AS- 2, AS-3, AS-4, AS-5, AS6 and AS-7) to be installed as part of this scope. Locations of the proposed wells are shown on Figures 2 and 3. The tasks required to perform the proposed scope of work are presented below. Site Safety Plan. As required by the Occupational Safety and Health Administration (OSHA) Standard "Hazardous Waste Operations and Emergency Response" guidelines (29 CFR 1910.120), and by the California OSHA (Cal-OSHA) "Hazardous Waste Operations and Emergency Response" guidelines (CCR Title 8, Section 5192), a Health and Safety Plan (HASP) will be prepared. The HASP will be reviewed by the field staff and contractors before beginning field operations at the site. Permitting. Permits for the proposed air sparge wells will be obtained from the SJCEHD prior to commencing with the field work. An Authority to Construct/Permit to Operate (ATC/PTO) will be obtained for the SVE System from the SJVAPCD and a Building Permit will be obtained from the City of Stockton prior to construction. Utility Locating. Prior to drilling, ATC will mark the locations of the proposed air sparge wells and trenching. A private utility locator will clear these locations. Underground Service Alert (USA) will be called to allow the local underground utility companies to identify the location of any utilities in the area of the proposed work. The air sparge wells will be cleared to a minimum depth of 5 feet bgs by air knifing. Shallow and Deep Air Sparge Well Installation. ATC will contract with a C-57 licensed drilling company to advance a total of six soil borings to be completed as three shallow-screened air sparge wells (AS-2 through AS-4) and three deep-screened air sparge wells (AS-5 through AS-7). The boreholes will be advanced to a total depth of 60 feet bgs for the shallow air sparge wells and to a total depth of 80 feet bgs for the deep air sparge wells using 8-inch diameter Hollow Stem Auger drilling equipment. The actual depth will be based on lithology encountered in the field. The wells will be completed using 2-inch diameter Schedule 40 PVC with 0.020-inch slot screen extending from 55 to 60 feet bgs or from 75 to 80 feet bgs. Once the well casing is installed, a filter pack consisting of#2/12 sand or equivalent will be emplaced in the annular space, extending up approximately two feet above the top of the well screen. A 3-foot thick layer of hydrated bentonite chips will be placed above the filter pack, and the remainder of the annular space will be backfilled with cement grout to a depth of approximately one foot bgs. The well casings will be set within flush-mounted traffic-rated well vaults. Soil samples for lithological description will be collected at 5- foot intervals to the total depth explored. Soil samples will be screened using a photo-ionization detector (PID) and any noticeable staining will be noted. At least two soil samples from each boring will be submitted for chemical analyses. The newly installed wells will be surveyed by a licensed surveyor to a local benchmark relative to mean sea level. Survey data including elevation, longitude, and latitude will be uploaded to the state GeoTracker database. Prior to operation of the remediation system, the air sparge wells will be developed by rigorously surging the well over the length of the screen interval and by purging until the extracted groundwater is deemed