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Wright has made estimates of residual dissolved TPHD and TPHG contaminant in the <br /> vicinity of MW-3. An assumed area and volume of groundwater (about 37,900 gallons) in <br /> the former tank area using an average concentration yields estimates of about 0.004 gallons <br /> of TPHD and about 0.00058 gallons of TPHG as residual dissolved near the former tank <br /> pit. In our opinion,the residual contaminant of TPHD is very small and depleted in volatile <br /> constituents, and the last TPHD detection did not match the diesel standard quantification. <br /> TPHG is negligible and has not been detected since 2001. Previous sampling of nearby <br /> water wells showed that these contaminants were not detected. <br /> On the basis of this information and estimate,it is our opinion that further monitoring is not <br /> warranted since; the tank sources have been removed and the dissolved TPHD residual <br /> contaminants are degraded at concentrations of less than 1,000 ug/I over three years. <br /> Wright recommends that site closure is appropriate at this time. <br /> The site is scheduled for continued quarterly sampling pending SJC EHD review and <br /> comment of this report. <br /> 6.0 Limitations <br /> This report has been prepared specifically for M&M Builders site at 8111 West Eleventh <br /> Street in Tracy, CA and was done according to the State and local agency suggested <br /> guidance documents for these investigations. The interpretations, conclusions and <br /> recommendations made herein are based on professional judgment of the data and analysis <br /> for the soil and water samples collected on-site and should be reviewed in the context of this <br /> report and other site reports. Wright Environmental Services, Inc. is not responsible for <br /> errors in laboratory analysis and reporting, or for information not available during the <br /> course of the study,and no warranty or guarantee is expressed or implied therein. <br /> If you have any questions,please call. <br /> Sincerely, E p <br /> Wright Environmental Services,Inc. � . <br /> �1ER M p �O <br /> 01"i'af <br /> fd° 1262 <br /> tYA CERTIFIED <br /> John L ch Christopher M. Palmer EG1��Fa RI`iG <br /> President HG 246,CEG 1262 GEOLCUST <br /> e yRy1 <br /> Attachments: '"'0 <br /> Table 1. Groundwater Well Water Levels,December 23,2004 <br /> Table 2. Groundwater Chemical Data,December 23,2004 <br /> Table 3. Historic Groundwater Chemical Data for Monitoring Wells <br /> Table 4. Historic Groundwater Data for Off-site Water Wells <br /> Figure 1. Groundwater Elevation Contours,December 23,2004 <br /> Figure 2. Groundwater Monitoring Well Sample Data,December 23,2004 <br /> IAW.. <br /> Page 4 of 6 <br />