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Stantec <br /> Report of Findings for the Waterfront Towers Separate Phase Hydrocarbon Investigation <br /> and Unocal Extraction Well Pilot Study <br /> Waterfront Towers Parking Lot <br /> March 4, 2011 <br /> and MtBE. Samples were collected in areas of highest headspace PID recordings during field <br /> observations and/or in areas where field staff observed physical changes in lithology or soil <br /> properties. The highest concentrations of TPHd and TPHg (5,900 and 960 mg/kg, respectively), <br /> were observed at approximately 43 feet bgs and within the course sandy layers. These layers <br /> also had the highest PID readings based on field observations. Additional analytical data for DP- <br /> 22 are included in Table 1. <br /> 3.5 UVOST RESULTS <br /> Soil analytical data observed from DP-22 correlated well with UVOST signals from adjacent <br /> borehole DP-23. The highest concentrations of hydrocarbons were observed at 31 and 43 feet <br /> bgs in DP-22 and the highest %RE signals for hydrocarbons using the UVOST were between <br /> 30 and 35 feet bgs and again between 42 and 47 feet bgs in DP-23 as were observed in the <br /> UVOST plots (Table 1 and Appendix D). Additional DP locations at the Waterfront Towers <br /> parking facilities are referenced on Figure 3 and discussed following: <br /> • In DP-24, the highest %RE was observed between 44 and 47 feet bgs using the UVOST <br /> with a maximum %RE of approximately 600. <br /> • In DP-25, based on field observations, there appeared to be refractory interference <br /> between six and ten feet bgs that is not anticipated to be related to hydrocarbons <br /> impacts. A %RE spike (approximately 12%) was also noted at approximately 36 feet <br /> bgs. <br /> • In DP-26, the highest %RE was observed between 25 and 34 feet bgs using the UVOST <br /> with a maximum %RE of approximately 22. <br /> • In DP-27, based on field observations, there appeared to be refractory interference from <br /> just below ground surface to approximately five feet bgs that is not anticipated to be <br /> related to hydrocarbon impacts. A %RE spike (-6%) was also noted at approximately <br /> 40 feet bgs. <br /> • In DP-28, the highest %RE was observed between 42 and 44 feet bgs using the UVOST <br /> with a maximum %RE of approximately 160. There were additional %RE spikes <br /> (approximately 40%) observed between 26 and 36 feet bgs. <br /> • In DP-29, the highest %RE was observed between 34 and 38 feet bgs and again <br /> between 44 and 46 feet bgs using the UVOST with a maximum %RE of approximately <br /> 300. <br /> • In DP-30, based on field observations, there appeared to be refractory interference just <br /> 10 below ground surface that is not anticipated to be related to hydrocarbon impacts. The <br /> highest %RE was observed between 14 and 16 feet bgs using the UVOST with a <br /> maximum %RE of approximately 22. <br /> 3.2 <br />