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May 25, 2018
<br />Page 6
<br />Pilot Study Workplan
<br />Diamond Foods Inc.
<br />2.5 PILOT TESTING — CALCIUM POLYSULFIDE INJECTION
<br />In accordance with Cardno ATC's Pilot Study Workplan and Notice of Intent (N01) dated November 7,
<br />2014, and subsequently approved by the RWQCB, Cardno ATC installed two observation wells and
<br />performed pilot testing activities at the site.
<br />On June 3 and June 4, 2015, Cardno ATC field staff supervised the installation of two groundwater
<br />nested observation wells, OBSW-S and OBSW-D. The wells were constructed to the depths of
<br />approximately 55 feet below ground surface (bgs) and 75 bgs, respectively. Shallow observation well
<br />OBSW-S was constructed with 10 feet of 0.010-inch slotted Schedule 40 2-inch diameter PVC casing
<br />extending from approximately 45 to 55 feet bgs. Deep observation well OBSW-D was constructed with
<br />5 feet of 0.010-inch slotted Schedule 40 2-inch diameter PVC casing extending from approximately 70
<br />to 75 feet bgs. On June 9, 2015, each observation well was developed using surge and bail
<br />techniques.
<br />On June 15, 2015, Cardno ATC personnel conducted pre-injection baseline monitoring and sampling
<br />from wells OBSW-S, OBSW-D, MW-1, MW-3, MW-6, MW-7 and MW-8. Wells were gauged, purged,
<br />and sampled in accordance with the RWQCB Monitoring and Reporting Program No. R5-2015-0012-
<br />003 for Diamond Foods, Inc., issued March 26, 2015.
<br />On June 16 and June 17, 2015, Cardno ATC supervised the injection of 1,500 gallons of calcium
<br />polysulfide (CPS), known commercially as Cascade® or Calmet®, into the water bearing formation
<br />below the site via existing well MW-3. To ensure that the calcium polysulfide solution was fully injected
<br />into the formation, approximately 100 gallons of clean chase water was subsequently injected into MW-
<br />3.
<br />On July 15, 2015, Cardno ATC personnel conducted the first of three post-injection monitoring and
<br />sampling events at the subject site. Cardno ATC monitored and collected samples from wells MW-3,
<br />MW-6, OBSW-S, and OBSW-D. Because the laboratory analyzed the samples for hexavalent
<br />chromium outside the EPA recommended holding time, the wells were resampled for hexavalent
<br />chromium on August 5, 2015. Results were presented in Cardno ATC's Well Installation and Pilot
<br />Study Report, dated October 2, 2015.
<br />Based on the results of the first round of injection, a second round was recommended and approved in
<br />2016. On February 14 through 16, 2017, ATC supervised the injection of 4,700 gallons of CPS into the
<br />water bearing formation below the site. Injection was conducted by Gregg Drilling & Testing (C57
<br />485165) using a specialized truck-mounted pumping rig connected to a temporary tank. Eight
<br />temporary injection tools were installed in soil borings advanced with a direct push rig. During the first
<br />day of injection operations, a tanker truck delivered 4,700 gallons of a 29% calcium polysulfide solution.
<br />The calcium polysulfide was transferred to a temporary tank and diluted with clean water on site to
<br />reduce it to a 15% calcium polysulfide solution prior to injection.
<br />On February 14, 2017, injection activities were initiated in the vicinity of monitoring well MW-6. A five
<br />foot injection tool was advanced using a direct push rig at boring I6-A to the target depth of 67 feet bgs.
<br />When the injection tool was set at the proper depth, a second injection tool was advanced in boring 16-
<br />B at a depth of 67 feet bgs. A total of 588 gallons of CPS was injected into each borehole mixed with
<br />725 gallons of water. After injection, a combined amount of 60 gallons of water was introduce to flush
<br />the lines and injection manifold of remaining solution. The total volume of liquid injected on February
<br />14, 2017 was 2,688 gallons.
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