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Work Plan for Phase 11 Environmental Site Assessment Page 3 Westlake Villages E, G, H, I, & J WKA No. 13221.02 July 13, 2021 response is suspected of having insufficiently verified buried utility locations or if our information discovers buried utilities. Soil Sample Locations WKA will divide the portion of the Site that is outside of the lakes into 64 cells. Each cell will represent an approximately 1.6-acre area. WKA will use geographic information system (GIS) techniques to identify sample location coordinates and a high-accuracy global positioning system receiver (GPSr)to locate sample coordinates in the field. WKA will collect a maximum of eight additional soil samples from soil stockpiles observed on the Site. Soil Sample Collection WKA will use a small solid stem auger drilling rig mounted on a Gator TM transportation platform to collect soil samples within two intervals at each location. The shallowest sample will be collected within the interval between one and 1'/2 feet below the ground surface, which will represent the soil excavated to construct the lake. The deeper sample will be collected within the six-inch interval beginning at the top of the original grade, which was buried beneath the soil placed as fill from the pond excavation. The deeper sample will represent soil that was at the original grade, and that may have received pesticides applied to the Site prior to the lake having been constructed. The soil borings will not exceed a depth of five feet below ground surface. WKA will use the Gator drilling rig to advance the boring to the required depths. WKA will clean the soil sampling tools before each use by washing them in a solution of clean water and a surfactant, then rinsing the tools in three baths of clean water. WKA will describe soil according to the Unified Soil Classification System (USCS) and will visually monitor soil for evidence of non-soil materials. The sample collection activity will result in WKA having collected 148 soil samples. WKA will place each soil sample into a laboratory-provided container that will be sealed using a Teflon TM-lined lid. WKA will label each sample container to indicate a unique sample number, sample location, time and date collected, and the sampler's identification. Each container will be preserved in a chilled cooler during transportation, with completed chain-of-custody forms, to California Laboratory Services (CLS), a California State Water Resources Control Board Environmental Laboratory Accreditation Program (ELAP) accredited laboratory. Laboratory Analyses The eight soil samples collected from stockpiled soil will be composited using a four-to-one ratio to construct two soil samples for analysis of OCPs and total arsenic. For samples collected using the drilling rig, WKA will request CLS to composite the 64 shallower samples using a four- to-one ratio to construct 16 samples for analyses. CLS will also composite the 64 deeper