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Mr.M. Scott Mansholt—CEMC Annual 2009 Groundwater Monitoring and Sampling Report April 3,2009 US Can-Welty Road Page 3 of 5 (SPO). MW-3 was not sampled from May 2006 until January 2008 due to insufficient water accumulation in the well. • Depth to Groundwater at Site: Ranged from 34.80 feet below top of casing (btoc) in MW-2 to 36.47 feet btoc in MW-1. Depth-to-groundwater measurements collected to date indicate that the average depth to groundwater at the site is 34.15 feet btoc. • Calculated Groundwater Elevation: Ranged from 69.91 feet above mean sea level (MSL) in MW-1 to 70.21 feet above MSL in MW-2. Groundwater elevation measurements collected to date indicate that the average groundwater elevation at the site is 71.46 feet above MSL. • Approximate Groundwater Flow Direction/Gradient: The groundwater flow direction and gradient could not be calculated due to an insufficient number of data points (less than three). Historical data for the site indicates that the groundwater flow direction is inferred to be to the east at 0.001 feet per foot. Depth to groundwater was measured in MW-1, MW-2, and MW-3 on February 11, 2009, using an oil/water interface probe. These measurements are provided in Table 1 along with historical depth-to-groundwater measurements, groundwater elevations, and product thickness. A map showing the February 2009 groundwater elevations is shown on Figure 3. Field data sheets are included as Attachment B. SAMPLING On February 11, 2009, following depth-to-groundwater measurements, MW-3 was purged using the three well casing-volume purge method due to a slow recharge rate. A disposable bailer was used for sampling. The pH, specific conductance, temperature, turbidity, and dissolved oxygen water-quality parameters were recorded during the purge process. Groundwater samples were collected at MW-3 following the three well casing- volume purge, and after the groundwater recharged to 80 percent of the static depth-to- groundwater level. Samples were not collected from MW-1 and MW-2 due to the historical presence of SPO. Samples were not collected from WFSMW-1 due to a concurrence by the RWQCB to discontinue monitoring and sampling in an August 2007 letter to CEMC2. Field data sheets are included as Attachment B. Laboratory-provided bottles were used to preserve the samples. The bottles were labeled, sealed, and placed immediately into an ice-cooled chest for delivery to Lancaster Laboratories, Inc. (Lancaster)under SAIC chain-of-custody protocol. Lancaster is a California-certified laboratory (ELAP #2116). 2. RWQCB—Central Valley Region,2007. Review of Second Quarter 2007 Groundwater Monitoring and Sampling Report—US Can-Welty Road Property,Vernalis,San Joaquin County. August 16.