|
August 11,2000 - 3 - 003-7170
<br /> In February 1994,the RWQCB requested that Owens-Brockway prepare and submit a workplan for a
<br /> ground water monitoring system to characterize the first water-bearing zone underlying the process
<br /> wastewater ponds(RWQCB 1994).
<br /> In July 1994, Nolte and Associates, Inc. (Nolte) prepared a workplan in response to the RWQCB
<br /> request(Nolte 1994). The workplan included a review of regional hydrogeologic conditions,land use,
<br /> locations of water supply wells, water balance analysis of the process wastewater ponds, and a
<br /> proposed ground water monitoring plan.
<br /> In April 1995, Clark Well, Inc., under contract to Nolte, installed four ground water monitoring wells
<br /> (MW-1 through MW-4). Two ground water monitoring wells (MW-1 and MW-2) were installed to
<br /> monitor upgradient water quality and two wells (MW-3 and MW-4) were installed to monitor
<br /> downgradient water quality. The locations of the monitoring wells are shown on Figure 2. Table 1
<br /> presents a summary of the well construction details.
<br /> Following installation, ground water samples were collected from wells MW-2,MW-3 and MW-4 and
<br /> analyzed for general minerals, metals and volatile organic compounds (VOCs). Well MW-1 was not
<br /> sampled due to insufficient water to obtain a sample.
<br /> Nolte concluded that upgradient ground water quality was poor with several constituents exceeding
<br /> secondary drinking water standards. Well MW-3 located immediately downgradient of the ponds
<br /> showed relatively higher concentrations of total dissolved solids (IDS), chloride, zinc and sulfate.
<br /> Low concentrations [less than 0.007 milligrams per liter (mg/L)] of 1,1 dichloroethylene (1,1 DCE)
<br /> were reported in samples collected from wells MW-3 and MW-4. 1,1 DCE and metals concentrations
<br /> were reported below maximum contaminant levels (MCLs). Nolte concluded that the combined
<br /> process water/stormwater percolation ponds were not adversely impacting the uppermost ground water
<br /> aquifer(Nolte 1995).
<br /> In August 1996,in response to a request from the RWQCB,Nolte sampled and analyzed ground water
<br /> from monitoring wells MW-2, MW-3, and MW-4 (Nolte 1996). During the sampling event,
<br /> monitoring well MW-1 was found to have an insufficient volume of water to collect a sample. Poor
<br /> ground water quality was reported in ground water samples collected from well MW-2 with electrical
<br /> conductivity (EC), and TDS exceeding secondary drinking water standards. Increases in EC, TDS,
<br /> calcium, magnesium, potassium, sodium, sulfate, chloride, nitrate, and mercury were observed in
<br /> ground water samples collected from well MW-3. No 1,1-DCE was detected and metal concentrations
<br /> were below MCLs. Ground water samples collected from well MW4 showed a slight increase in EC,
<br /> TDS, calcium, magnesium, and sulfate compared to samples collected from well MW-2. Nolte again
<br /> concluded that the combined process water/stormwater percolation ponds were not adversely
<br /> impacting the uppermost ground water aquifer(Nolte 1996).
<br /> In May 1998 and September 1999, Golder measured water levels and collected ground water samples
<br /> from monitoring wells MW-2, MW-3, and MW-4. Ground water samples were analyzed for general
<br /> minerals. Monitoring well MW-1 was dry during both sampling events. The results of the May 1998
<br /> and September 1999 sampling events are presented in the reports prepared by Golder, "May 1998
<br /> Ground Water Monitoring Report, Owens-Brockway Glass Containers, Tracy, California, dated June
<br /> 30, 1998" (Golder, 1998), and "September 1999 Ground Water Monitoring Report, Owens-Brockway
<br /> Glass Containers,Tracy, California, dated November 29, 1999"(Golder, 1999), respectively.
<br /> In accordance with the WDR's, ground water and process pond monitoring is currently being
<br /> conducted by Golder on a quarterly and monthly basis, respectively. The most recent quarterly
<br /> Roo-37.doc Golder Associates
<br />
|