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Abdelwahed Facility, Ultramar Site No. 13792 May 9, 2013 Stockton California NFAR Request and Well Destruction Work Plan f shown on Figure 4. Isoconcentration contours for TPHg, benzene and DCA in groundwater are shown on Figures 4, 5 and 6, respectively. Historical groundwater monitoring data are summarized in Table 1. ADDITIONAL GROUNDWATER INVESTIGATION Second quarter 2012 monitoring data for well MW -1 continued to indicate high hydrocarbon groundwater concentrations. Well MW -1 is located in area of the southeast -dispenser -island area which has been identified as the source area for hydrocarbon impacts to soil and groundwater. The recalcitrant hydrocarbon concentrations detected in MW -1 groundwater were likely due, in part, to hydrocarbon and biological fouling of the then 9 -year-old well. Horizon recommended that well MW -1 be drilled out and replaced with a well (MW -13) in close proximity which would yield data representative of source area groundwater conditions and possibly be used for dual-phase extraction, if necessary. Horizon obtained EHD well permit SR# 0065067 to destroy well MW -1 and install replacement well MW -13. A copy of the EHD permit is contained in Attachment A. Underground Services Alert was contacted to mark underground utility locations. Fieldwork conducted during this investigation included: drill out of well MW -1 and backfill of the boring; installation of replacement well MW -13; well development; and collection of groundwater sample from well MW -13. The MW -13 location is shown on Figure 2. Fieldwork was conducted according to, where applicable, California Well Standards Bulletins 74-81 and 74-90, EHD Well Standards, and Horizon Field Methods and Procedures (Attachment Q. Well Destruction and Well Installation Fieldwork Well destruction and well installation fieldwork was conducted on 2 and 3 July 2012. Horizon oversaw All Well Abandonment (AWA) of Sacramento, California (C-57 license #848359) destroy well MW -1 and install well MW -13. Mr. Harlin Knoll of the EHD was present to witness grouting of the well MW -1 over -bore and installation of well MW -13. Well MW -1 (55 feet total drilled depth) was destroyed by over-drilling with 8 -inch diameter hollow -stem augers to 56 feet below surface grade (bsg). Neat grout cement was emplaced in the bore hole via a tremie pipe set to within three feet of the bottom of the bore hole. The grout was brought up to within one foot of the surface. The MW -1 well box was left in place and will be removed at a later time. The upper foot of the bore hole inside the well box was backfilled to the surface with native soil. The well MW -13 boring was advanced utilizing 8 -inch diameter augers to a total depth of 61 feet bsg. Soil samples were collected at 5 -foot intervals from 5 feet bsg to the total depth of the boring with a slit -spoon sampler. Soil samples were field screened using a photo - ionization detector (PID). Groundwater was first encountered at 40 feet bsg. The well MW - 13 boring soil descriptions, soil field screening data, soil sampling information and well construction details were recorded on a field boring log. Soils were described in the Unified Soil Classification System (USCS). Drill cuttings from the well destruction and the MW -13 1792 NFAR rpt.doc Project No. 1792.26 2 HORIZON ENVIRONMENTAL INC.