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M • <br /> 2.0 Field Investigations <br /> This section outlines the rationale and field activities that are planned for the ten-year <br /> sampling event and the additional investigation at the former bagging plant near <br /> Monitoring Well KP-3. <br /> 2.1 Ten-Year Sampling Event <br /> 2.1.1 Rationale for the Ten-Year Sampling Event <br /> As discussed in the previous section,the purpose of this ten-year soil sampling event is to <br /> assess the success of phytoremediation in removing nitrogen from soil.The results from this <br /> ten-year sampling event will be compared to data collected during the 2006 five-year <br /> sampling event and to baseline concentration data collected in 2000.The ten-year evaluation <br /> will also include an evaluation of ten years of groundwater monitoring and analytical data. <br /> As presented in the RAP,the criteria for success of phytoremediation at ten years are <br /> (CH2M HILL,2000): <br /> • Stabilized and possibly decreased concentrations of nitrogen in groundwater <br /> • An indication that natural processes continue to affect nitrogen concentrations in soil <br /> 2.1.2 Field Procedures <br /> During the ten-year sampling event,composite soil samples will be collected from seven <br /> sampling areas.One sampling area is located north of the warehouse.Two sampling areas <br /> are located at each of the former bagging plant,stormwater pond,and the original test <br /> grove/turnaround area planting locations.Figures 2 through 5 show the approximate <br /> locations of the seven sampling areas(shown as 35-foot diameter circular areas and <br /> numbered 1K through 7K). Within each circular area,borings will be advanced using a <br /> hand-auger or direct-push technology rig at eight locations to a total depth of 6 feet Soil <br /> samples from each boring will be divided into three depth intervals,0 to 2 feet,2 to 4 feet, <br /> and 4 to 6 feet.The eight samples from each depth interval will be composited and <br /> submitted to a laboratory for analysis.The soil samples will be analyzed for Total Kjehldahl <br /> nitrogen(TKI),nitrogen as nitrate,nitrogen as ammonia,and pH,in accordance to the RAP <br /> (CH2M HILL,2000).Soil samples from areas 3K and 4K,near the former bagging plant <br /> shown on Figure 4,will also be analyzed for exchangeable and soluble ammonium. <br /> 2.2 Additional Investigation at Former Bagging Plant <br /> 2.2.1 Rationale for Conducting Additional Investigation at the Former Bagging <br /> Plant <br /> Data recorded since third quarter 2002 indicate that nitrate,ammonia,and conductivity <br /> measurements at Monitoring Well KP-3 fluctuate,but have generally increased over <br /> concentrations historically detected at this well (CH2M HILL,2010). Additional <br /> investigation activities are proposed to determine if there is a nitrate source area and to <br /> define its extent at the former bagging plant near Monitoring Well KP-3.This proposed field <br /> ai <br />