Laserfiche WebLink
30350 South Tracy <br /> Tracy, CA <br /> Page 2 <br /> impact has occurred to groundwater. Also, due to the highly permeable lithology of the site <br /> which is primarily composed of layers of gravels and sand, and the presence of contaminant <br /> in the soil to as deep as 124 feet bsg (BH2 sample), a potential threat to groundwater still <br /> exists. <br /> EHD is not aware of any quarterly sampling conducted after March 2003. Continuous <br /> quarterly sampling and reporting of the groundwater monitoring wells is required according <br /> Tide 23, Division 3, Chapter 16, Section 2652(d) of California Code of Regulations. Sample <br /> the wells by July 15, 2003 if you have not conducted the second quarter sampling of 2003. <br /> EHD requests at least 48-hour notification of all future sampling events. <br /> The lateral extent of the contamination in the soil around the aggregate base plant (BH-1 to <br /> BH-4) has not been defined. Additional investigation is required. Also, since only two <br /> monitoring wells exist in the area of the rock-processing plant, a third triangulation <br /> monitoring well is needed for calculating local groundwater flow direction. Submit a work <br /> plan that will define the lateral extent of the contamination in the soil and installation of a <br /> third monitoring well in the area of the rock-processing plant to EHD by August 15, 2003. <br /> EHD recommends submitting split samples for the next quarterly monitoring event to <br /> different laboratories in order to verify the non-diesel pattern consistently reported with the <br /> analytical results. <br /> EHD has not determined if over-excavation is required at this time. However, provide an <br /> estimate of when the projected final active phase of the plant is planned to EHD if you wish <br /> to pursue over-excavation as a remediation alternative. You may submit this information in <br /> the next quarterly sampling report. <br /> A copy of the manufacturer's details of the discrete bladder pump that RMC has installed in <br /> the three monitoring wells was submitted to EHD on July 2, 2003. EHD has reviewed the <br /> information and agreed the bladder pumps are suitable for groundwater sampling. <br /> Please direct any questions to Jeffrey Wong at (209) 468-0335. <br /> Donna Heran, REHS, Director <br /> Environmental Health Department <br /> C. <br /> Jeffrey Wong, Senior REHS Margaret Lagorio, REHS <br /> LOP/Site Mitigation Unit N Supervisor <br /> Cc: CRWQCB, Central Valley Region—James L.L. Barton, RG <br />