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April 30, 2018 Page 9 Pilot Study Workplan Diamond Foods Inc. 4.0 PROPOSED SCOPE OF WORK To evaluate the effectiveness of calcium polysulfide at reducing hexavalent chromium site, ATC proposes to conduct additional testing in which a calcium polysulfide solution would be injected into temporary soil borings. 4.1 PLANNING AND PERMITTING Upon approval of the work plan by the RWQCB, ATC will obtain the necessary permits from the San Joaquin County Environmental Health Department (SJCEHD) for advancement of the proposed borings. ATC assumes the scope of work can be performed under the existing NOI and MRP. The Site Specific Health and Safety Plan will be updated to include activities proposed in the work plan. ATC will schedule and supervise a private utility locator to locate underground lines in the area of the proposed drilling. In addition, ATC personnel will conduct a site walk and mark the surface of the site for Underground Services Alert (USA). As required, USA will be contacted at least 48 hours prior to initiating drilling activities to allow time for utility companies to identify underground lines, pipes, or cables that may be affected by the drilling activities. ATC will schedule field personnel, procure injection solution, and perform any other necessary field preparation and job start-up activities. 4.2 SOIL BORING ADVANCEMENT AND INJECTION ACTIVITIES ATC will supervise the advancement of eight soil borings by a C-57 licensed drilling company. ATC proposes to advance four borings near the nested observation wells and four borings near monitoring well MW-5. The proposed boring locations are shown on Figure 3. The borings will be advanced utilizing a truck-mounted Geoprobe® narrow diameter drilling rig employing direct push technology. Soil samples will not be collected from the borings. ATC will arrange for a tank truck with 4,700 gallons of a 29% calcium polysulfide solution to be delivered at the site. The solution will be diluted with additional clean water to approximately 10% calcium polysulfide and then injected directly into the water formation at each point through a temporary screen. In six of the borings, temporary screens will be set at depths from approximately 40 to 55 feet below ground surface. In two of the borings adjacent to the observation wells, the temporary screens will be set at depths from approximately 55 to 75 feet below ground surface. The depth may be adjusted slightly depending on the actual depth to water at the time of injection. The injection will occur simultaneously at 2 or 4 points at a rate of 5-10 gallons per minute. The depth to water and pH will be monitored in the nearby wells during injection activities. The borings will be grouted to the surface following completion of injection. 4.3 POST-INJECTION MONITORING ATC proposes to conduct three post-injection monitoring events at intervals of one, three and six months following injection. These monitoring events are intended to establish an effective treatment area of influence and to determine if a rebound in hexavalent chromium concentrations occurs. In each monitoring event groundwater samples will be collected from the observation wells and monitoring wells using the low-flow sampling methods. Groundwater samples will be analyzed in accordance with the requirements of M RP R5-2015-0012-003.