NC0004961_RBSS CSA Report_Appendix F_SW and Sediment Characterization_20150818

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Surface Water and Sediment
Characterization
• Sampling Procedures
• Sampling Variances

Sampling Procedures
Surface Water Samples
There are eight surface waters located in the anticipated groundwater flow direction at the site
between the ash basin and Mountain Island Lake.
WITHIN ASH BASIN
Surface water samples will were collected from the Primary and Secondary Cells at the
approximate open water locations (SW-AB1 and SW-AB2). 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 was slowly lowered
to the desired depth to collect the sample. The sample thief and sample was retrieved and the
sample will be transferred to the appropriate sample containers provided by the laboratory. In
areas where the water body is less than 5 feet deep, water samples was collected from the
location at a depth just above the ash surface. Ash basin surface water samples will be
analyzed for the same constituents as groundwater samples. Select constituents will be
analyzed for total and dissolved concentrations and speciation.
Seep Samples
Water samples were collected from the seep sample locations as described herein. These seep
sample locations (designated as S-1 through S-13) 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 laboratory analysis. Select constituents will be
analyzed for total and dissolved concentrations as well as speciation.
In March 2014, DENR conducted sampling of seeps and surface water locations at the site.
HDR received the analytical results from this sampling event and provided the data herein.
Analytical results from the seep sampling were reviewed to determine if similar speciation
analyses were to be performed for selected seep locations.
After analytical results for seep samples are reviewed, a determination will be made concerning
collection of off -site seep samples. If it is determined that off site seep samples are to be
collected, the DWR regional office will be contacted.
Sediment Samples
Sediment samples will be collected from the bed of the seep sample locations as described
herein (designated as S-1 through S-13). The S-13 location will be considered a background
sediment sample. The sediment samples were analyzed for total inorganics using the same
constituents list proposed for the soil and ash samples. Due to safety concerns, sediment

samples will not be collected at this time where open water or ponded water is present within
the ash basin.

Sampling Variances

Variances from Groundwater Assessment Work Plan
Surface Water and Sediment Characterization