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EnviroTech Consultants, Inc. Page 13 Site Investigation: Sampling Report Louise Avenue Water Treatment Facility 4.0 SECONDARY SOIL SAMPLE COLLECTION 4.1 Secondary Sampling (September 12, 2018) Following the initial sampling on April 16, 2018, EnviroTech recommended collecting a resample at COL2- 1 from the surface to 6 inches, collecting an additional background sample and additional sample locations in Area 3 to determine the full vertical and lateral extents of the arsenic impacted soil within the retention pond. On September 12, 2018, soil samples were collected using a hand auger at pre-determined locations. The latitude and longitude of soil sampling locations were determined with a hand-held GPS and coordinates are provided in Attachment 5. The soil sampling locations are identified in Figures 7 and 8. The second background sample was collected from the surface to 6 inches bgs northwest of the retention pond. The resample of COL2-1 was collected from the surface to 6 inches bgs in the same location as the original COL2-1 (Figure 5). At the original sample locations in Area 3, COL3-4 was advanced to 5 feet using a hand auger and samples were collected from 2 to 3 feet bgs, 3 to 4 feet bgs, and at 5 feet bgs. Due to the high density of cobbles and boulders, sample locations COL 3-1, 3-2, 3-3 and 3-5 were not extended to 5 feet, and secondary samples for these locations were not collected. Eight additional sample locations in the retention pond were selected south of COL3-5 and east of COL3- 4 in an area approximately 20 feet by 40 feet. In each sampling location (where possible) the hand auger was advanced to 5 feet bgs. The soil was examined to determine if there is any discoloration or staining. A soil sample was collected from the surface to 6 inches bgs, 1 to 2 feet bgs, 2 to 3 feet bgs, 3 to 4 feet bgs,and 5 feet bgs.At COL3-10 and COL3-12,the hand auger could not be advanced to 5 feet bgs because of the high density of cobbles and boulders. Samples were collected from surface to 6 inches and 1 to 2 feet bgs at COL3-10 and from the surface to 6 inches, 1 to 2 feet bgs, and 2 to 3 feet bgs at COL3-12. The soil sampling equipment was cleaned and washed with a non-phosphate containing detergent, rinsed with water, and dried before use and between each soil sample collection. All soil samples were placed in glass jars capped with Teflon-lined lids, labeled with the soil sample location number, depth, time and date. The labeled jars were placed in zip-lock bags in a cold ice chest and transported under chain-of-custody procedures to BC Laboratories for analysis. All soil samples were analyzed for the presence of arsenic by EPA Method 6010-B, with solubility testing conducted as needed. Analytical testing was accomplished in accordance with the guidelines established in BC Laboratories Quality Assurance Manual, applicable standard operating procedures, and other related documentation. 5400 Rosedale Highway 0 Bakersfield, CA 93308 0 Tel 661.377.0073 Fax 661.377.0074