FIELD DOCUMENTS AND WORK PLANS 1992-1999

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' HARGIS-ASSOCIATES, INC. • ' Timothy J. Verhagen, Esq. July 16, 1993 Page 5 1 period April 27 through May 6, 1993. Instantaneous pumping rates for reclamation wells ranged from 9 gallons per minute (gpm) to 108 gpm. Average pumping rates ' for reclamation wells during the previous quarter were estimated from totalizer data recorded on February 2 and April 27, 1993, except for intermediate zone reclamation well I-5. The average pumping rate for this well could not be ' determined due to inconsistency of totalizer data. Average pumping rates for reclamation wells ranged from 4 gpm to 62 gpm. 4.0 DISCUSSION Comparison of water level data obtained in January-February 1993 with data ' obtained in April -May 1993 from shallow zone, 100-foot sand, intermediate zone, and deep monitor wells and nonpumping reclamation wells indicates that water levels increased in the site vicinity during this period. Increases in water levels during this period ranged from approximately 1.6 feet in deep zone monitor ' well MW-462 to approximately 5.9 feet in shallow zone monitor well MW-7. Hydraulic gradients and directions of groundwater flow in the 100-foot ' sand, intermediate zone, and deep zone in April -May 1993 were similar to those in January-February 1993 (H+A, 1993) . The analytical results for groundwater samples collected during April -May 1993 from shallow zone wells, 100-foot sand wells, and deep zone monitor wells and reclamation wells indicate that concentrations of total dissolved chromium detected in groundwater samples are generally within the range ' of concentrations detected historically in groundwater samples collected from these wells with the following exceptions. Concentrations of total dissolved chromium detected in groundwater samples from intermediate zone reclamation ' wells I-9 (MW-321) and I-10 (MW-324) , and from intermediate zone monitor well MW-326 increased from 0.921 mg/l , 0.512 mg/1 , 0. 128 mg/l in January-February 1993 to 1 .23 mg/l , 0.723 mg/l , and 1 .96 mg/1 , respectively in April -May 1993 (Figures 5 through 7) . Total dissolved chromium was detected for the first time in the groundwater sample collected from the Cuneo domestic well at a concentration of 0.016 mg/l ' (Figure 8) . This result should be compared with the data to be collected during the July 1993 quarterly groundwater and performance monitoring event to confirm the potential presence of total dissolved chromium. The Cuneo domestic well is located on Walker Lane south of the Mormon Slough (Figure 3) . The increases in total dissolved chromium concentrations detected in groundwater samples collected from intermediate zone reclamation wells I-9 and I-10, intermediate zone monitor well MW-326, and the Cuneo domestic well may 1