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Musco Family Olive Company - 18 - 12 December 2006 Staff's evaluation of on-site constitutent occurrences is discussed above. The Report evaluates well MW-1, MW-3, MW-5, MW-11, MW-13 through MW-16, and W-2. The primary COCs evaluated are TDS, chloride, and sodium. Many of the wells discussed in the Report indicate increasing trends of COCl: Wells MW-1, MW-3, MW-5, MW-14, MW-16, and W-2. Those with no significant changes in COCs were MW-11, MW-13, and MW-15. The Report does not offer any explanation of the elevated concentrations of several constituents in the wells and fails to address the issue of long-term degradation of groundwater due to spray irrigation. The Report does not address the fact that Musco has been land applying high strength wastewater to their fields since at least 1991, which has elevated the COCs in groundwater above background groundwater concentrations. The Report identifies well MW-1 with increasing trends of COCs that cannot be explained without up-gradient data_ When the Time Series Plot and TDS plot of MW-1 are reviewed it appears that concentrations of COCs were initially low. However, as the well was purged and sampled over time and more formation water was brought into the well, the COCs began to rise sharply as indicated in the plots. It is staff's opinion the Reports explanation is invalid and an approximate 800 mg/L increase in TDS from early 2002 to mid-2003 is not representative of natural background conditions. The Report does not mention impacts of groundwater by spray irrigation as a possible source of contaminants to well MW-1. The Report discusses increasing trends in wells MW-3, MW-5, MW-14, MW-16, and W-2. The Report's discussion provides little understanding as to the source of constituents detected in groundwater. It provides no comparison to groundwater outside the impact zone nor does it look at other possible constituents such as bicarbonate as a chemical signature of wastewater. According to the Report, wells MW-11, MW-13, and MW-15 show no significant changes over time. Again, the Report's only focus is on the constituent trend and not the elevated TDS, chloride, and sodium concentrations and provides no explanation for the elevated concentrations in groundwater. It makes no comparison to offsite groundwater quality nor does it look at other possible constituents such as bicarbonate as a chemical signature of wastewater_ Groundwater quality was also evaluated by plotting isoconcentration maps for the COCs detected in the shallow/intermediate zones (as one) and deep zone. Upon review of the primary COCs (TDS, chloride, and sodium) isoconcentration maps, it is evident'that elevated concentrations exist in groundwater. The Report suggests these concentration levels are "both naturally occurring and some of them are detected in the process water." However, the Report does not provide any information of naturally occurring concentrations or background water quality. The isoconcentration maps indicate elevated concentrations of CDCs in a pattern that stretches from the uplands to the lowlands. Based upon review of the June 2006 Potentiometric map, the shallow groundwater flow is not completely defined offsite, and although the current wells appear to have elevated COCs, the current well network is inadequate for defining the limits of the contaminants. The Reports overall theme concerning constituents of concern is that the swale funnels groundwater and is holding the CDCs, allowing them to buildup over time. The Report asserts that background concentrations are more accurately defined as "ambient concentrations. "Ambient concentrations include both naturally occurring constituents in aquifers and changes