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§eofogicafTecfwks Inc. Page 4 <br /> Groundwater Monitoring Report <br /> Project No. 723.2 <br /> April 20,2001 <br /> f'3.0 CONCLUSIONS & RECOMMENDATIONS <br /> 1 <br /> Conclusions <br /> 1. The groundwater contaminant plume is not defined vertically or laterally. <br /> 2. Groundwater flow trends to the northeast to east. The southerly flow direction on <br /> December 4, 2000 appears to be anomalous. <br /> 3. High levels of BTEX and TPH-G are present in the groundwater of all six water table <br /> monitoring wells. Low concentrations of BTEX and TPH-G are present in the deep <br /> well. <br /> . 4. The main OFCs (MTBE, DIPS, ETBE, TAME & TBA) appear not to be present in the <br /> groundwater at concentrations above detection limits listed in the data table. <br /> 5. Oxidation-Reduction Potential measurement (Table 3) shows that all seven wells are <br /> screened in areas of the groundwater plume that are affected by the biodegradation <br /> reactions occurring within the plume. This corroborates well with the laboratory data. <br /> Recommendations <br /> 1. Investigate the vertical and lateral extent of the groundwater plume. GTI submitted a <br /> L0 "Vertical Definition Work Plan" to SJC PHS/EHD by facsimile on August 24, 2000 <br /> (Original sent certified mail and received/signature receipt by SJC PHS/EHD on August <br /> 29, 2000). We request that the County review this work plan.and provide approval or <br /> L comments by mid May 2001 so that this project can move forward. <br /> 2. Continue quarterly groundwater monitoring, with the next monitoring event scheduled <br /> in June 2001. <br /> r 3. Due to the infrequent detection of the oxygenated fuel compounds at this site, future <br /> quarterly monitoring events will not include analysis by EPA method 8260. However, <br /> testing for.MTBE by 8020/602 is justified. <br /> 4.0 LIMITATIONS <br /> This report was prepared in accordance with the accepted standards and practices of the <br />€ j field of environmental geology, groundwater hydrology and good business practices. It <br /> ' should be recognized that definition and evaluation of environmental conditions is a <br /> difficult and inexact science. Judgments leading to conclusions and recommendations are <br /> generally made with an incomplete knowledge of the site-specific conditions present. <br /> u <br /> The tasks proposed and completed during this project were reviewed and approved by the <br /> Llocal regulatory agency for compliance with the law. No warranty, expressed or implied, <br /> is made. <br /> �1 <br />