NC0004987_Appendix F_Surface Water and Sediment Characterization_20150908

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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-1 through SW-5). At each location, two water samples were collected —one
sample close to the surface (i.e., 0 foot to 1 foot from surface) and one sample at the
approximate middle depth of the water body. Prior to sampling, the depth to ash was measured
by slowly lowering a measuring stick or tape until the ash surface was 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 was transferred to the appropriate sample containers provided by the
laboratory. The middle depth sample varied based on the water level in the water body. In areas
where the water body is less than 5 feet deep, one water sample was collected from the location
at the approximate middle depth of the water body. Ash basin surface water samples were
analyzed for the same constituents as groundwater samples. Select constituents will be
analyzed for total and dissolved concentrations.
Ash is located beneath the water in the ash basin at the proposed locations for surface water
samples SW-1 and SW-2. The water body where surface water sample SW-3 is proposed was
used for the plant's ash handling system and the water level fluctuates daily. Surface water
samples SW-4 and SW-5 were proposed in water bodies that contain mainly pyrites beneath the
water. It was expected that some ash is located beneath the ponded water where SW-3, SW-4,
and SW-5 were proposed.
OUTSIDE ASH BASIN
One water sample will be collected from the surface water located southeast of the ash basin
(SW-6). This surface water sample will be analyzed for the same constituents as groundwater
samples. Select constituents will be analyzed for total and dissolved concentrations.
A water sample was previously collected from the proposed location SW-6 in September 2014
as part of Duke Energy's NPDES permit renewal application package. The sample location was
referred to as S-1 for the September 2014 sampling event. The analytical results indicated
exceedances of 213 Standards for several constituents: iron, manganese, sulfate, and TDS.
Duke Energy collects surface water samples from Lake Norman from upstream and
downstream locations for their existing NPDES permit requirements. If water sample analytical
results indicate potential for impacts to Lake Norman, then surface water quality data collected
in Lake Norman will be reviewed.
Analytical results for surface water samples collected from outside the ash basin were
compared to 15A NCAC 2B .0200 Classifications and Water Quality Standards Applicable to
Surface Waters and Wetlands of North Carolina (2B Standards), from the DWR, and EPA
Criteria Table, last amended on May 15, 2013.

Seep Samples
A potential seep sample location was previously identified east of the ash basin dam (S-2).
During the July and August 2014 seep sampling event performed as part of Duke Energy's
NPDES permit renewal application, there was no flow and, therefore, the potential seep
sampling location was not sampled. If there is seep flow that will allow for proper sample
collection at the time of this assessment work, a seep sample was proposed to be collected
from the S-2 location. If collected, the seep sample was proposed to be analyzed for the
constituents listed in Table 5 of the Work Plan. Select constituents will be analyzed for total and
dissolved concentrations.
Sediment Samples
Due to the exceedances of 2B Standards at surface water sample location SW-6 (referred to as
S-1 for September 2014 sampling event), one sediment sample was collected from the bed
surface of the surface water at this location. The streambed sediment sample was analyzed for
total inorganics using the same constituents list proposed for the soil and ash samples.
In addition, a sediment sample was collected in conjunction with seep sample S-2 if seep flow
allowed for a proper seep sample to be collected. If collected, the sediment sample was
analyzed for total inorganics using the same constituents list proposed for the soil and ash
samples.
Due to safety concerns, sediment samples were not collected where open water or ponded
water was present within the ash basin.

Sampling Variances

4
Variances from Groundwater Assessment Work Plan
Surface Water and Sediment Characterization
As Proposed . - -.
Seep S-2
Surface water SW-5
Not Applicable Turbidity of seep sample was greater than 10 NTUs
Not Applicable Turbidity of surface water sample was greater than
10 NTUs