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Ms. Foley-Gannon - 2 - September 25, 2006 Pulte Homes, 'Manteca t Calcium Soluble Nitrate Iron Chloride Sulfate Manganese Sodium "Background" 4,510 20 11,100 180 330 303 200 Pond Sample#1 36,600 991 15,600 730 600 324 2480 Pond Sample#2 20,000 193 11,600 970 760 2390 2480 Based on the limited data set provided by Kleinfelder that shows elevated and, for some constituents, soluble wastes remaining in the pond soils, these remaining waste constituents in the ponds soils could adversely affect groundwater quality. Furthermore, there is no data or any assessment regarding the potential of the wastes to impact the health of future residents . at the site. Groundwater data was presented in Kleinfelder's May 18, 2006 report and was discussed by Kleinfelder personnel and Regional Board Staff on June 8, 2006. Kleinfelder asserted that groundwater was not impacted at the site due to the lack of waste constituents in the former monitoring wells, MW-1 and MW-2, and presented a hydraulic gradient map showing MW-2 directly downgradient of the former wastewater pond. We note that sample results presented were from 2006 with a very limited suite of analytes3, the gradient information was inconclusive and, in fact, other quarters of data show gradients inconsistent with the map presented. Also, the adjacent unlined irrigation ditch could have influenced the water quality in those two shallow wells. Groundwater grab samples from November 2005 were also presented in the May 18, 2006 report. Three samples, GP-4, GP-5 and GP-6, were in areas potentially affected by the waste pond. Again, the analytical suite performed on the samples was very limited. Even so, all three samples contained elevated levels of iron in excess of the water quality standard. One sample, GP-6 located in the vicinity of the former location of MW-2, had elevated levels of total dissolved solids (970 mg/I) and manganese (1.53 mg/1), both of which exceed the water quality standard. Again, based on the limited data set provided by Kleinfelder that shows elevated levels of known pond wastes in the groundwater, some of which exceed the water quality standards, we can only conclude that the ponds may have adversely affected water quality at the site. Regional Water Board staff suggested to Kleinfelder in early June of this year, that this issue could be addressed with a shallow groundwater sample taken from groundwater beneath the former pond. The cost of this type of investigation is minimal. In the case groundwater is impacted additional work maybe necessary to identify the extent of any impacts and develop remedial plans. To proceed with development of the pond area without further information could result in greater costs at a later date. As was our previous understanding, Pulte Homes should complete the cost recovery acknowledgement form and provide a work plan for testing the residual waste in the former 'No laboratory data sheets were provided; Iron,TDS, chloride and sodium are not reported,inanganese values appear to be misreported.