SU0005250 - Laserfiche WebLink

Home Browse Search

Musco Family Olive Company - 21 - 12 December 2006 s g. Staff rejects the Report's assertion that "the most representative background groundwater quality are COC levels detected historically and recently in the offsite area immediately down-gradient of W-2." Background groundwater quality must be determined using well data from the shallow and deep zones within the mid-fan and distal fan facies of the alluvial fan environment. Using offsite wells east of the facility locates the wells in the furthest distal portion of the fan that grades into valley sediments., h. Staff rejects the proposed "Ambient Concentrations" and concludes that a single set of background groundwater concentrations must be established from the shallow and E deep zones being monitored within.the mid-fan and distal fan facies of the alluvial fan Eenvironment. i RECOMMENDATIONS Based on the current average concentrations for COCs detected in groundwater wells shown in Table 8, the majority of the monitoring wells contain elevated concentrations of TDS, € chloride, sodium, and bicarbonate that exceeds the interim limits. This indicates'that spray irrigation and wastewater leaking from the Reservoir and 1-million gallon pond has impacted groundwater. Based on the wastewater COC concentrations presented in Table 1 and Table E 3, the wastewater significantly exceeds background concentrations, applicable water quality objectives and could or has impacted the groundwater beneficial uses, and thereby is a "Designated.Waste per the California Water Code, Division 7, Section 13173(b). Water quality objectives for several parameters are listed in Table10. Table 10 i Water Quality Objectives Constituents/ Water Quality Goals' Parameters Groundwater Surface Water EC (pmhoslcm) 7002 7002 pH 6.5-8.42 6.5-8.42 TDS (mg/1) 4502 4502 Chloride (mg/l) 1062 1062 Sodium (mg/1) 692 'A Compilation of Water Quality Goals (RWQCB-CV, 2004, http://www.swrcb.ca.gov/rwgcb5/) 2Agricultural Water Quality Goals (Food &Ag. Org. of United Nations) Based on the findings discussed in this evaluation, staff has the following recommendations: n • 1. Background concentrations limits must be established for groundwater and surface water in accordance with WDR No. R5-2002-0148 and No. R5-2005-0024. Background groundwater concentrations must be established from locations within the mid-fan and distal fan facies of the alluvial fan environment outside of the impact zone.