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Mr. Ken Gillies <br /> Gillies Trucking <br /> 3931 Newton Road, Stockton <br /> Page 5 of <br /> 5. The hydrogeological model is not clear at this time to the EHD. The <br /> inferred groundwater flow direction depicted on Figure 7 of the QR is <br /> based on two wells screened in the First Riverbank sand interval and two <br /> wells screened in the Second Riverbank sand interval. UEC estimates the <br /> hydrological conductivity of the intervening fine-grained interval to be 1015 <br /> cm/sec. If correct, with such a tight unit separating the sand intervals, it is <br /> likely that groundwater in the two sand units act semi-independently — it is <br /> not surprising that the groundwater elevation isocontours in Figure 7 <br /> should be so contorted. Each sand interval should have at least three <br /> wells screened exclusively in it to properly infer the flow direction and <br /> monitor dissolved contaminants in the down-gradient direction. <br /> 6. An estimate of the sorbed and dissolved contaminant masses remaining <br /> at the site in each hydrological unit incorporating the latest data has not <br /> been presented to the EHD. <br /> 7. An estimate of the sorbed contaminant mass in the vadose zone has not <br /> been prepared and submitted to the EHD. <br /> 8. A fate and transport model for the contaminants has not been presented <br /> which would demonstrate adequate attenuation of the plume of impacted <br /> groundwater such that existing sensitive receptors will not be impacted, <br /> future groundwater supplies will not be threatened, that the plume will not <br /> present a threat to human health, and that the plume will attenuate to <br /> background conditions in a reasonable time frame. <br /> 9. A fate and transport model for the contaminants addressing the items <br /> noted in bullet 8 above under the influence of a rise of groundwater into <br /> the Modesto Formation has not been submitted. <br /> The EHD is also concerned that as of yet, it appears that quarterly groundwater <br /> monitoring of your site has not been performed in 2004; the EHD has no <br /> proposal or record of approving suspension of quarterly monitoring on file. <br /> Failure to perform quarterly monitoring, as has been directed for your site, will put <br /> your site out of compliance with the EHD directives and may adversely affect <br /> your eligibility for reimbursement from the State Cleanup Fund. Please <br /> immediately resume quarterly groundwater monitoring. <br /> Finally, please note that laboratory analytical results for your site are not being <br /> electronically submitted to GeoTracker, the State Water Resources Control <br /> Board database program. Please initiate submission of all required data files to <br /> the GeoTracker system immediately. <br /> By 02 August 2004, please submit to this office a work plan in the context of a <br /> site conceptual model to complete the vertical and lateral delineation of impacted <br /> groundwater on your site, addressing all open or questioned issues noted in this <br />