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MPCOSTCO.001C/LGH21L134434 Page 3 of 5 December 17, 2021 © 2021 Kleinfelder www.kleinfelder.com KLEINFELDER 24411 Ridge Route Dr., Suite 225, Laguna Hills, CA 92653 p | 949.727.4466 f | 949.727.9242 Soil will be sampled from each borehole using a hand auger for samples collected from depths less than 5 feet bgs and using a DPT drive sampler lined with 0.75-inch diameter polyvinyl chloride (PVC) sample sleeves of up to 4-foot in length for soil samples collected from deeper than 5 feet bgs. Discrete soil samples will be collected from the six 10-foot boreholes at approximate depths of 1 foot, 2.5 feet, 5 feet and 10 feet bgs. Discrete soil samples will be collected from the two 20- foot boreholes at approximate depths of 1 foot, 2.5 feet, 5 feet, 10 feet, 15 feet and 20 feet bgs. The sample depths may be adjusted based field observations, such as the presence of hydrocarbon or chemical staining or odor, which may warrant the retention and submittal of a soil sample from between these depths. Following retrieval of the hand-auger barrel or drive sampler, some of the soil contained within it will be screened in the field for the presence of total volatile organic vapors using a calibrated photo-ionization detector (PID), and the reading obtained will be logged in the field, along with a visual description of the soil. The four discrete soil samples collected at 1 foot, 2.5 feet, 5 feet and 10 feet bgs from each of the six 10-foot borings will be composited 4 to 1 by the laboratory for analysis. The 1 foot, 2.5 feet, 5 feet and 10 feet bgs soil samples from each of the two 20-foot borings will be composited 4 to 1 by the laboratory for analysis. The 15 feet and 20 feet bgs samples from both the deeper borings will be composted by the laboratory into a singe 4 to 1 composite sample. A total of nine 4 to 1 composite soil samples will be submitted for laboratory analysis. Soil samples collected using the hand auger will be transferred into wide-mouthed glass jars provided by the analytical laboratory, whereas samples collected in PVC sample sleeves will be submitted to the laboratory in cut sleeve segments capped with Teflon™ film and securely-fitting plastic end caps. The portion of each soil sample to be submitted for laboratory volatile organic compound (VOC) analysis will be preserved in the field in accordance with United States Environmental Protection Agency (US EPA) Method 5035A. Based on lab capabilities, the soil samples submitted for VOC analysis may not be composited by rather, one soil sample from each of the composite group will be analyzed as a discrete sample. In addition, other groundwater parameters maybe added to support the preparation of a National Pollution Discharge Elimination System (NPDES) permit application. Each sample container to be submitted for analysis will be labeled and placed into a water ice-chilled cooler pending transport to a state-accredited laboratory for analysis. Kleinfelder field staff, under the supervision of a State of California-licensed Professional Geologist, will prepare lithologic logs of the soil encountered during the drilling activities. Soil samples from the borings will be logged in accordance with the Unified Soils Classification System. Additionally, based on groundwater studies completed in the vicinity of the Site, groundwater is anticipated to be encountered between 10 and 20 feet bgs. If groundwater is encountered in the two deeper borings, one discrete “grab” groundwater sample will be collected using disposable bailers from each of the borings. A slotted PVC pipe will be inserted into the open boring and allowed to set for up to two hours to allow for groundwater accumulate. If after two hours, no groundwater accumulates into the borehole, the PVC slotted pipe will be pulled, and the borehole will be grouted from the bottom up with a Portland cement – bentonite mixture. Likewise, the six 10-foot borings will be grouted from the bottom up with a Portland cement – bentonite mixture after the collection of the proposed soil samples.