Laserfiche WebLink
• • • . <br /> Site Assessment Work Plan Addendum— August 2017 <br /> SAVE-ON GAS (Former Rainwater Car Wash) <br /> 420 West Yosemite Avenue, Manteca, California <br /> 1.0. INTRODUCTION <br /> At the request of Mr. Satinder Dilawri of Save On Gas, Advanced GeoEnvironmental, Inc. <br /> (AGE) has prepared this Additional Site Assessment Work Plan for 420 West Yosemite <br /> Avenue, Manteca, California (site). A site location map is included as Figure 1. On-site <br /> monitoring wells, soil borings, UST locations are illustrated in Figure 2. Off-site soil boring <br /> locations are illustrated in Figure 3. The lateral and deep extent of methyl tert butyl ether <br /> (MTBE) impact to groundwater is illustrated in Figures 4 through 7. Well construction <br /> details for existing monitoring and remediation wells are summarized in Table 1. Historical <br /> groundwater analytical data are included in Tables 2 and 3. <br /> AGE previously performed additional off-site assessment in January 2017 by advancing <br /> four(4) soil borings (P-11, P-12, P-14, and P-15) to depths of 115 feet bsg. Results of the <br /> investigation detected elevated levels of MTBE to the north and northwest of the site in <br /> grab groundwater samples collected from borings P-12, P14, and P-15 in water bearing <br /> Zone B. The contamination plume in water bearing Zone B remains undefined north and <br /> northwest of offsite borings P-12, P-14 and P-15. Due to the groundwater impact <br /> encountered at P-12, P-14 and P-15, the Central Valley Regional Water Quality Control <br /> Board (RWQCB) directed by letter dated 23 May 2017 (Appendix A) that groundwater <br /> additional deep borings were needed to confirm previous grab groundwater sample <br /> results from soil borings; and the installation of a groundwater monitoring well to establish <br /> groundwater trends and to evaluate the stability of the plume. <br /> Based on RWQCB letter dated 23 May 2017, soil samples have not been collected at the <br /> site at depths shallower than 10 feet below surface grade (bsg) to compare with the <br /> criteria established in the State Water Resources Control Board's Low Threat Closure <br /> Policy (LTCP). <br /> This work plan has been prepared in accordance with guidelines established by RWQCB <br /> for the subsurface investigation of UST sites. This soil boring and monitoring well <br /> installation work plan details procedures for the advancement of three on-site shallow (5- <br /> foot) soil borings, two deep soil borings for collection of grab groundwater samples as <br /> well as installation of one deep groundwater monitoring well to potentially fully assess <br /> hydrocarbon impact from leaking underground storage tanks (USTs) previously located <br /> at the site. <br /> 2.0. SCOPE OF WORK <br /> The scope of work includes the drilling of three (3) on-site shallow soil borings; one (1) <br /> off-site soil boring to a maximum depth of 115 feet for collection of grab groundwater <br />