ARCHIVED REPORTS XR0009904 - Laserfiche WebLink

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Corrective Action Plan Page 8 for excavation or de-watering operations to induce surface settlement over an extended area, the limitations that the shallow water table and the public streets on the down- gradient and co-gradient boundaries of the site impose on excavations intended to remove contaminated soil from the subsurface, and the regulatory limits on discharges to surface waters and to the air Strategic Design Considerations The following issues were identified to have strategic influence on the selection of a remediation technology for this site ❑ The soil strata beneath the water table include extensive formations of loose to very loose, highly permeable sands ❑ Two old, un-reinforced, brick structures (i a the RAS Car Wash building at 124 East 11th Street and the Tracy Auto Parts building at 208 East 11th Street) are located less than 60 ft beyond the boundaries of the site ❑ Gasoline contanunation in groundwater has moved down gradient from the ' location where the underground storage tanks formerly on the site were situated, (see Figure 2 for location) and has crossed the boundaries of the property along its frontages on East 11th and "F" Streets 0 The preponderance of highly contaminated soil in the subsurface is at, or close to, the elevation of the water table Concentrations of components of ' hydrocarbons in soil decrease rapidly with depth below the water table It is suspected that localized pockets of contaminated soil may be present in the zone between the subsurface and the water table in the area beneath and immediately adjacent to the structure that served as the pump island (see Figure 2 for location) when a service station was operated at the site ❑ East 11th Street is a principal thoroughfare in the City of Tracy, is heavily trafficked and has recently been reconstructed The subsurface beneath the streets and sidewalks is extensively populated with underground utilities The City of Tracy's engineering staff have indicated that excavation in the streets would not be permitted r ❑ The City of Tracy's waste water treatment plant is operating at its full hydraulic capacity The City will not permit any groundwater from a remediation program, either untreated or treated, to be discharged to the sanitary sewer ❑ The City of Tracy will permit discharge of treated ground water to the municipal storm-water sewers subject to the discharge being controlled by a National Pollutant Discharge Elimination System (NPDES) permit, or other discharge authorization, issued by the CRWQCB