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Currently, groundwater at the site is monitored by network of six monitoring wells: Wells MW -4, MW -5, MW -8, and SB -1 monitor a shallow aquifer. Wells MW -6 and MW ® 7 monitor a deeper aquifer. In August 2011, the County submitted an EMP Workplan to further characterize the nature and extent of VOCs migrating from the CHSL in accordance with the Order. The workplan outlined a program for temporary and permanent well construction, sampling, analysis, and data evaluation. This Workplan was approved by RWQCB staff in late August 2011. A revision to this EMP workplan allowing the use of Hydropunch'"° sampling methods for temporary well construction was submitted and approved by RWQCB staff in September 2011. 3.1 Well Construction Methods In accordance with the workplan, the County's drilling contractor, Gregg Drilling, Inc., drilled three temporary boreholes - MW -9, MW -10, and MW -11— at the locations shown on Figure 1. Boreholes were drilled using eight -inch diameter hollow stem auger techniques under the direct field supervision of a State of California Certified Engineering Geologist and Certified Hydrogeologist. Lithologic samples were collected at five-foot intervals and logged by the field geologist to ensure proper stratigraphic correlation with existing site monitoring wells. Boreholes were advanced through the Holocene alluvium and into the Pleistocene Corcoran Clay member of the Tulare Formation. Logs of boreholes are presented in Attachment 1. Once the Corcoran Clay was reached, drilling stopped to prepare the Hydropunch'"^ sampler. Attempts to drive the Hydropunch'" into the Corcoran Clay were unsuccessful as a result of the density and stiffness of the formation. Under the advisement of the field geologist and in accordance with the first version of our approved workplan, the driller was directed to advance the borehole into the Corcoran Clay until water was encountered. A one -inch diameter Schedule 40 PVC casing with 0.010 -inch slots was installed at this depth, and the borehole was backfilled with No. 2/12 sand until the perforated section of the casing was surrounded by the sand pack. The temporary wells were secured at the ground surface using plywood weighted down with sand bags. Temporary well construction information is summarized on the following table: Well Completion ReportIC Page ■ 2 Corral Hollow Sanitary Landfill A S S O 6 1 A T H 3 December 15, 2011