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HomeMy WebLinkAboutNC0022406_Appx F_SW and Sediment Characterization_20150909nNNci iu in Surface Water and Sediment Characterization • Sampling Procedures • Sampling Variances Sampling Procedures Surface Water Samples WITHIN ASH BASIN Surface water samples were collected from the ash basin at the approximate open water locations (SW-AB1 through SW-AB9). At each location, two water samples were collected — one sample close to the surface (i.e., 0 to 1 foot from surface) and one sample at a depth just above the ash surface (i.e., 1 foot to 2 feet above the ash to avoid suspending the ash within the sample). Prior to sampling, the depth to ash was measured by slowly lowering a measuring stick or tape until the ash surface is encountered, being careful to avoid suspending the ash. The depth to ash was noted, and a sample thief will be slowly lowered to the desired depth to collect the sample. The sample thief and sample was retrieved and the sample was transferred to the appropriate sample containers provided by the laboratory. In areas where the water body was less than 5 feet deep, one water sample was collected from the location at a depth just above the ash surface. Ash basin surface water samples were analyzed for the same constituents as groundwater samples. Select constituents will be analyzed for total and dissolved concentrations. OUTSIDE ASH BASIN Four surface water samples were collected from outside of the ash basin. Two samples were collected from the Dan River. Samples SW-DR-U and SW-DR-D will be obtained upstream and downstream, respectively, from the confluence of Little Belews Creek with the Dan River. Two samples were also obtained from Belews Lake. Samples SW-BL-U and SW-BL-D were obtained upstream and downstream, respectively, of the BCSS (including the steam station, ash basin, Pine Hall Road Ash Landfill, and structural fill). The upstream samples were considered background surface water samples. These surface water samples were analyzed for the same constituents as groundwater samples. Select constituents were analyzed for total and dissolved concentrations. Analytical results for surface water samples collected from outside the ash basin were compared to 15A NCAC 213 .0200 Classifications and Water Quality Standards Applicable to Surface Waters and Wetlands of North Carolina (213 Standards), from the DWR, and EPA Criteria Table, last amended on May 15, 2013. Seep Samples Water samples were collected from the seep sample locations. These seep sample locations (designated as S-1 through S-11) were collected near the time of the monitoring well sampling to minimize concerns about potential temporal variability between surface water and groundwater and analyzed for the same constituents as groundwater monitoring wells. Select constituents were analyzed for total and dissolved concentrations. In March 2014, DENR conducted sampling of seeps and surface water locations at the site. HDR has included the analytical results from this sampling event herein and will review the data and determine if changes in the proposed seep or surface water locations is needed. Sediment Samples Sediment samples were collected from the bed surface of the four surface water sample locations outside of the ash basin (designated as SD-DR-U, SD-DR-D, SD-BL-U, and SD-BL-D) and the seep sample locations (designated as S-1 through S-11). The SD-DR-U and SD-BL-U locations were considered background sediment samples. The sediment samples were analyzed for total inorganics using the same constituents list proposed for the soil and ash samples. Sampling Variances 4 3 Variances from Groundwater Assessment Work Plan Surface Water and Sediment Characterization • . . - - . Collect and analyze sediment Sediment samples were not samples at each CSA and NCDENR collected. seep location. Collect surface water sample SW- AB3 within ash basin. Collect surface water sample SW-10 at base of ash basin dam. Sample was not collected Sample was not collected Oversight. Sediment samples at the CSA and NCDENR seep locations will be collected and analyzed during the next CSA sampling event and submitted for analysis. Safety issues related to collecting sample where shown on Work Plan Figure 3. Surface water sample location SW-AB2 should provide adequate representation of water quality in ash basin main pond. Location of SW-10 is nearly identical to NCDENR seep location ABW that was collected.