Laserfiche WebLink
5.0 RECOMMENDATIONS <br /> Based on the preceding evaluation of current groundwater monitoring results and trends, JDS offers <br /> the following recommendations: <br /> • Based on the declining and low concentrations of TPH and BTEX in the vicinity of well MW-1, <br /> the declining concentrations of MtBE to levels below the CA secondary MCL of 5 ug/l, and the <br /> lack of potential receptors at this site, the RWQCB should consider closure with respect to the <br /> former UST and petroleum hydrocarbon impacts to groundwater. <br /> • Although the concentrations of nitrate in groundwater indicate continued impacts from off-site <br /> sources,they have decreased in virtually all the wells to levels approaching or levels below the CA <br /> primary MCL of 45,000 ug/l (Figure 7). As such, it is recommended that Mr. Hof should no <br /> longer be responsible to monitor for nitrate in groundwater, and that the RWQCB should <br /> consider closure with respect to nitrate. <br /> • Concentrations of the pesticide compound b-BHC appear to have decreased to levels at or below <br /> 0.1ug/l since April 2002 (Figure 8). The RWQCB has expressed that site closure will be <br /> considered when it can be shown concentrations of b-BHC are declining to acceptable water <br /> quality standards. Several conservative risk-based regulatory values have been established for b- <br /> BHC ranging from 0.02 ug/I (USEPA Integrated Risk Information System [IRIS])to 0.25 ug/1 <br /> (CA Prop 65, No Significant Risk LeveUl in 100,000 cancer risk). Since concentrations of b- <br /> BHC in well MW-3 occur within the range of regulatory values, appear to be in decline, and do <br /> not appear to pose a threat to human health or the environment, the RWQCB should close this <br /> site with respect to b-BHC. <br /> • It is understood that the RWQCB has requested plans to abandon wells MW-8 and MW-9, and <br /> that Mr. Hof has been denied access to well MW-8 by the neighboring property owner. The <br /> RWQCB has agreed to allow Mr. Hof to abandon all wells concurrently pending a site-wide <br /> ruling for no further action to which JDS recommends. <br /> CMfmm_Ggtrll 8 iu spm C..�Wb�Is Ml <br />