Laserfiche WebLink
Evaluation of Natural Attenuation: 7500 West Eleventh Street, Tracy, CA. Page 52 <br /> r_ <br /> Xi <br /> f-� 10.0 RECONOMNDATIONS <br /> SJC has the following recommendations for future environmental management of the <br /> 7500 West Eleventh Street site. <br /> ' 10.1 Technology for Groundwater Remediation. <br /> Monitored natural attenuation should be selected as the technology for remediation of the <br /> 7500 West Eleventh Street site. <br /> 10.2 Groundwater-quality Monitoring Program <br /> Having established that processes of natural attenuation are acting to decrease the <br /> contaminant load in the plumes of affected groundwater at the 7500 West Eleventh Street <br /> f site, guidance taken from ASTM Standard E 1943-98 indicates that an appropriate future <br /> groundwater-quality monitoring program should involve annual recovery of samples <br /> from Monitoring Wells MW-3, MW-13, MW-7, MWhP-3, MW-14, MW-16, MW-18, <br /> MW-11 and MW-19 which wells lie along the longitudinal axis of the primary plume of <br /> -' contaminated groundwater, and from Monitoring Well MW-12 in the secondary plume. <br /> However, the results of the statistically defensible MAROS analysis that are presented in <br /> Section 8.2.2.5 of this report, use of which the US-EPA advocates to ensure that <br /> monitoring programs are statistically efficient, calls for temporarily continuing to monitor <br /> groundwater quality in Monitoring Wells MW-3, MW-7 and MW-13 on a quarterly <br /> -r' schedule, but to reduce the sampling frequency for all other wells in the monitoring array <br /> to a maximum of once per year. <br /> 10.2.1 June 2005 -March 2006 Ouarterly Monitoring <br /> Given the guidance developed above, SJC recommends that, for the period June 2005 <br /> through March 2006, samples be recovered from the following wells on a quarterly <br /> schedule: <br /> • MW-3, MW-13, MW-7, MWFP-3, MW-14, MW-16, MW-18, MW- <br /> 11 and MW-19, all of which are located along the longitudinal axis <br /> of the primary plume. <br /> • MW-2, MW-5 and MW-17, located on the western periphery of the <br /> primary plume (the latter to monitor the migration of MTBE into <br /> that area which appears to be associated with development of the <br /> groundwater mound in the vicinity of Monitoring Well MW-16 that <br /> is described in Section 2.1 of this report). <br /> • MW-4 and MW-10, which are located on the eastern periphery of <br /> the primary plume; <br /> v , <br /> SJC <br />