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GrEOMATMIX SUE HEALTH & SAFETY PLAN 3.1 SITE HISTORY Simplot operates one stormwater pond and three Class II surface impoundments at a fertilizer manufacturing plant in Lathrop. Discharge to these impoundments is regulated by the California Regional Water Quality Control Board—Central Valley Region (RWQCB) under Waste Discharge Requirements (WDRs) Order 97-229. Simplot regularly collects samples and water level measurements from existing groundwater monitoring wells surrounding the impoundments, inspects and collects samples and inflow data from each impoundment and from leachate collec- tion and recovery systems, and collects samples from lysimeters that monitor the vadose zone. These data are reported to the RWQCB on a quarterly basis. The monitoring program is regulated by the RWQCB under the WDRs and Monitoring and Reporting Program No. 97-229, which was adopted as a part of the WDRs. The Class II surface impoundments and the associated water quality monitoring programs must also comply with the provisions of Title 27. The current groundwater monitoring network consists of four groundwater monitoring wells and six suction lysimeters. Wells LP-1, LP-2, and LP-3 are considered compliance wells, and well PW-1-48 is considered a background well. The compliance wells are apparently screened below the uppermost part of the aquifer, and may be screened in two different water bearing zones, which are separated by a thick clay layer. In a December 18, 2000 meeting with RWQCB staff, Simplot proposed to install a new moni- toring well system to more fully comply with the detection monitoring provisions of Title 27. The RWQCB requested the submission of a work plan by March 1, 2001 for the installation of additional monitoring wells and a background well. 3.2 SITE PHYSICAL DESCRIPTION The facility is located on the south end of the City of Lathrop in San Joaquin County, California (Figure 1). The site includes four existing groundwater monitoring wells, six suction lysimeters, a stormwater pond, and three Class II surface impoundments (North, South, and West Ponds). 3.3 TYPE OF FIELD WORK The scope of work consists of drilling, installing, developing, and sampling four groundwater monitoring wells. 3.4 SCOPE OF FIELD ACTIVITIES List and number all field tasks for project: 1. Drilling and Well Installation 2. Well Development 3. Initial Well Sampling I:IPROJEM6741.00016741-07.doc 2