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• II <br /> 27 May 1992 <br /> (GeoAudit MDC Ukiah-1. 9) <br /> Page 2 of 5 <br /> OVERESCAVATION <br /> 300 South State Street <br /> Ukiah, California <br /> PROCEDURES <br /> Excavation of contaminated soil at 300 South State Street was <br /> performed in three phases. The first phase was performed between 12 <br /> and 15 August 1991. The second and third phases took place on 1 <br /> April and 29 April 1992, respectively. This approach was necessary <br /> due to limited space. <br /> During the excavation process, the soil was screened for the <br /> presence of organic vapors utilizing a photo-ionization detector <br /> (PID: Thermo--Environmental 580A, lamp energy 10. 0 eV, calibrated to <br /> isobutylene) . Soil which did not indicate the presence of organic <br /> vapor was segregated from soil that did indicate elevated organic <br /> vapor readings. <br /> PHASE I EXCAVATION <br /> During this phase, approximately 2 , 200 cubic yards of contaminated <br /> soil were excavated from the eastern half of the property and <br /> stockpiled on the western portion of the property. The soil was <br /> removed to a depth of 14 f eet. As per the request of Ms. Janice <br /> Goebel of the RWQCB, the excavation was limited to 3 feet along the <br /> eastern property line. The approximate limits of the excavation is <br /> depicted on Figure 3 . The soil was stockpiled on and covered with <br /> 10 mil polyethylene sheeting pending treatment. <br /> To confirm the successful removal and to document the level of <br /> remaining contaminated soils, samples were collected from the base <br /> of each of the three sidewalls at 10-foot lineal intervals (Figure <br /> 3) . These samples were analyzed for total petroleum hydrocarbons <br /> (TPH) in accordance with DHS method-gasoline and for purgeable <br /> aromatic hydrocarbons (BTE&X) in accordance with EPA method 8020. <br /> To suppress the release of volatile organic compounds into the <br /> atmosphere, the excavated soil was sprayed with water. Nutrients, <br /> consisting of nitrogen, phosphoric acid and soluble potash were <br />. added during this soil removal process. <br /> During the excavation process, monitoring wells MW-1, MW-3 and MW-5 <br /> were destroyed. <br />