NC0004979_Attachment 1_20141015

Attachment 1
Allen Steam Station
NC0004979
Toe drain information

Allen Steam Station
Ash Basin Surface Water and Seep Monitoring
August and September 2014
Introduction
Flow and water quality measurements were collected from nine seep sampling locations(S-1 through S-
9)and two surface water locations near the ash basin (Lake Wylie-Upstream and Lake Wylie-
Downstream)associated with Duke Energy's Allen Steam Station, located in Gaston County, North
Carolina.The purpose of the sampling, which was conducted in late August and early September 2014,
was to measure seepage flows and provide sufficient depth to allow collection of water quality samples for
laboratory analysis. Samples were collected via a combination of methods as described below. See
Figures 1 and 2 for maps of the approximate sampling locations. Descriptions of the seep sampling
locations are provided in Table 1.
A description of the engineering drainage systems for earthen dams at the Cliffside Steam Station Ash
Basin is located in Appendix C.
Seep Flow Measurement Method and Results
A V-notch weir apparatus was utilized at locations S-1, S-2, S-3, and S-4 to impound the seepage in a
channel, which concentrated discharge to a central location that allowed for flow measurements to be
obtained.The weirs were constructed from %-inch-thick Plexiglas board material. Each device was
inspected after installation and prior to sampling to confirm sufficient flow and depth for sampling, and to
verify that only minimal leakage, if any, was present. Sufficient time was allowed for the impounded
seepage flows to reach equilibrium discharge flow before flow measurement and sampling.
Flow measurements at seep sampling locations S-5, S-6, and S-7 were collected by installing a 2-inch-
diameter PVC pipe into the ground surface where the seep emerged. Seepage in these locations was
diffuse,with no defined channel. Each PVC pipe was inserted in the location to direct flow through the
pipe. Flow from the pipe was observed until the discharge appeared to be clear of visible fines prior to
sampling for water quality analysis.
Flow measurements at locations S-8 and S-9 were collected from two outfalls consisting of 12-inch-
diameter corrugated metal pipes(CMP). Based on a conversation with Duke Energy personnel familiar
with the site, the source of water discharging from these pipes is unknown. These outfalls exhibited flow
during a dry-weather visual assessment consisting of least 72 hours prior to a rainfall event. The source
of persistent flow from these outfalls is assumed to be groundwater and not stormwater.
The seepage flows at locations S-1 through S-9 were measured using the timed-volumetric method. A
volume of water was collected from the discharge of the weir directly into an appropriately sized container.
Volumes(in mL)were measured in the field utilizing a graduated container.The amount of time(in
seconds) needed to collect the volume of water was recorded and flows(in MGD)were calculated for the
timed-volume.The calculated flows(in MGD)at each seep location are presented in Appendix A.
Seep Water Quality Sample Collection Method and Results
Water quality samples were collected at locations S-1 through S-9.To minimize potential effects of
stormwater runoff, seep samples were collected during a period with minimal preceding rainfall. Samples
were collected from the discharge flow at the flow measurement devices described above or directly
1

from the seep into sample bottles while minimizing disturbance and entrainment of soil/sediment.
Analytical parameters for analysis were:TSS, TDS, Oil &Grease, Cl, SO4, F, COD,Al,As, B, Ba, Ca, Cd,
Cu, Cr, Fe, Mn, Mo, Mg, Ni, Pb, Sb, Se, TI, Zn, Hardness, and Hg. Storage and preservation techniques
of the samples, after collection and prior to analyses, were followed according to Appendix B.Analyses
were conducted by Duke Energy's Huntersville analytical laboratory(NC Wastewater Certification#248)
and Pace Analytical Laboratories(NC Wastewater Certification#12). Laboratory analytical methods used
for each parameter are provided in Table 2 and analytical results are presented in Appendix A.
Seep In-situ Measurement Method and Results
In-situ field parameters(temperature, pH, and specific conductance)were measured at locations S-1
through S-9 utilizing calibrated field meters either at the discharge of the seep directly,at the discharge of
the flow measurement devices, or in the water pool created behind the device, if sufficient water depth did
not exist at the device discharge.The analytical results are presented in Appendix A.
Lake Wylie Water Quality and In-situ Sample Collection Method and Results
Water quality samples and in-situ measurements from were collected at a location upstream (Lake Wylie-
Upstream) and downstream (Lake Wylie-Downstream)of the ash basin (Figure 2).The grab samples
were collected from the surface(0.3 m)directly into appropriate sample bottles. Preservation and
analyses methods for the lake samples are provided in Table 2 and Appendix B. The analytical results are
presented in Appendix A.
Recommendations
The low volume of flow at each seep location, coupled with the relatively low constituent concentrations in
the samples, suggests that there is little potential for Allen Steam Station to influence water quality in Lake
Wylie. If reasonable potential analyses demonstrate that there is no potential to exceed water quality
standards, then Duke Energy proposes to re-evaluate the seep locations listed in this document annually
over the next 5-year permit cycle. These annual evaluations would be documented and would verify the
condition of the existing seeps and determine the presence of new seeps.
The North Carolina Department of Environment and Natural Resources—Division of Water Resources
(DWR)will be promptly notified if any new seeps are identified or any significant changes are observed
for the existing seeps. If any existing or newly identified seeps are determined to reach Lake Wylie, and
demonstrate reasonable potential to exceed a water quality standard, Duke Energy will do one of the
following: 1)stop the seep, 2)capture and route the seep so that it is discharged through a National
Pollutant Discharge Elimination System (NPDES) permitted outfall, or 3)address the seep using Best
Management Plans approved by DWR.
Most of the analytical results upstream and downstream of the ash basin discharge in Lake Wylie with the
exception of copper and zinc are at, or near, the method detection limits and below limits for water quality
standards. Measured values at these two locations are consistent with historical data from previous
monitoring efforts in Lake Wylie. Duke Energy proposes that the semi-annual in-stream monitoring
frequency be maintained.
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Table 1 —Allen Steam Station Surface Water/Seep Locations and Descriptions
Seep Location Coordinates' Flow
ID Description
Seep Description
Latitude Longitude
S-1 35°10.242' 8100.625' Continuous Located south of Active Ash Basin, north of Nutall Oak Lane.Tributary towards Lake
Wylie.Well-defined stream approximately 3-ft wide.
S-2 35010.426' 8100.344' Continuous Located southeast of Active Ash Basin.Tributary towards Lake Wylie.Well-defined
stream approximately 1-ft wide.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-3 35010.513' 8100.360' Continuous approximately 2-ft wide.Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-4 35010.513' 8100.360' Continuous approximately 1.5-ft wide. Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
S-5 35010.621' 8100.366' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-6 35010.626' 8100.369' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-7 35010.664' 81°0.380' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-8 35010.706' 8100.391' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
S-9 35011.146' 8100.394' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
Notes:
1. Location coordinates(degrees)for seep sampling locations are approximate, and are in NAD 83 datum.
2. Flow description for each seep sample location is based on observation during site visits performed by HDR Engineering, Inc. (HDR)on August
21, 2014. Flow measurements and analytical samples were collected on September 4 and September 9, 2014.
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Table 2—Laboratory Analytical Methods
Parameter Method Reporting Units Laboratory
Limit
Chemical Oxygen HACH 8000 20 mg/L Duke Energy
Demand COD
Chloride(CI) EPA 300.0 1 mg/L Duke Energy
Fluoride(FI) EPA 300.0 1 mg/L Duke Energy
Sulfate(SO4) EPA 300.0 1 mg/L Duke Energy
Oil and Grease EPA 1664B 5 ug/L Pace Analtyical
Mercury(Hg) EPA 245.1 0.05 ug/L Duke Energy
Aluminum(AI) EPA 200.7 0.005 mg/L Duke Energy
Barium(Ba) EPA 200.7 0.005 mg/L Duke Energy
Boron (B) EPA 200.7 0.05 mg/L Duke Energy
Calcium(Ca) EPA 200.7 0.01 mg/L Duke Energy
Hardness EPA 200.7 0.19 mg/L(CaCO3) Duke Energy
Iron(Fe) EPA 200.7 0.01 mg/L Duke Energy
Magnesium(Mg) EPA 200.7 0.005 mg/L Duke Energy
Manganese(Mn) EPA 200.7 0.005 mg/L Duke Energy
Zinc(Zn) EPA 200.7 0.005 mg/L Duke Energy
Antimony(Sb) EPA 200.8 1 ug/L Duke Energy
Arsenic(As) EPA 200.8 1 ug/L Duke Energy
Cadmium (Cd) EPA 200.8 1 ug/L Duke Energy
Chromium (Cr) EPA 200.8 1 ug/L Duke Energy
Copper(Cu) EPA 200.8 1 mg/L Duke Energy
Lead(Pb) EPA 200.8 1 ug/L Duke Energy
Molybdenum (Mo) EPA 200.8 1 ug/L Duke Energy
Nickel (Ni) EPA 200.8 1 ug/L Duke Energy
Selenium (Se) EPA 200.8 1 ug/L Duke Energy
Thallium(TI) Low Level EPA 200.8 0.2 ug/L Duke Energy
TDS SM2540C 25 mg/L Duke Energy
TSS SM2540D 5 mg/L Duke Energy
4

Appendix A
Seep Flows and Analytical Results
Appendix A-1

Allen Steam Station
Surface Water/Seep Monitoring Analytical Results-September 2014
Seep Monitoring Location' Lake Wylie- Lake Wylie-
S-1
Units Y Y
S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 Upstream2'3 Downstream2'3
Oil &Grease mg/I <5 <5 <5.0 <5 <5 <5.0 <5 <5 <5 N/A WA
COD-Chemical Oxygen Demand mg/I <20 <20 20 <20 <20 <20 <20 <20 <20 N/A N/A
Cl-Chloride(00940) mg/I 4.3 49 32 41 59 62 7.8 7.5 9.1 N/A N/A
FI-Fluoride mg/I 0.11 0.1 0.13 <0.1 <0.1 0.11 <0.1 0.17 <0.5 N/A N/A
SO4-Sulfate(00945) moll 1.4 10 26 21 42 55 74 87 180 N/A WA
Hg-Mercury(71900) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
AI -Aluminum (01105) mg/I 0.996 0.467 0.039 0.022 <0.005 0.21 0.083 0.01 0.254 WA N/A
Ba-Barium (01007) mg/I 0.044 0.114 0.044 0.047 0.208 0.307 0.057 0.060 0.029 N/A N/A
B-Boron (01022) mg/1 <0.05 0.871 0.555 0.713 0.927 1.01 0.934 0.606 1.49 WA N/A
Ca-Calcium mg/I 7.34 7.25 61.7 73.4 20.7 19.8 17.8 97.6 138 N/A N/A
Hardness mg/I(CaCO3) 31.9 74.4 203 251 111 112 76 292 413 WA N/A
Fe-Iron (01045) mg/I 1.86 1.25 0.136 0.215 <0.01 0.015 0.113 0.011 0.942 N/A N/A
Mg-Magnesium mg/I 3.29 13.7 12 16.4 14.4 15.2 7.69 11.7 16.5 N/A N/A
Mn-Manganese(01055) mg/I 0.356 0.305 0.131 0.310 1.45 2.25 0.395 <0.005 0.998 N/A N/A
Zn-Zinc(01092) mg/I <0.005 <0.005 <0.005 <0.005 0.011 <0.005 <0.005 <0.005 0.283 3.08 <2
Sb-Antimony(01097) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 N/A N/A
As-Arsenic(01002) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cd-Cadmium (01027) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cr-Chromium(01034) Ng/I 1.42 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cu-Copper(01042) lig/I <1 <1 <1 <1 <1 1.14 <1 <1 1.31 2.80 2.60
Pb-Lead(01051) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Mo-Molybdenum Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 N/A N/A
Ni-Nickel(01067) pgll <1 1.58 <1 <1 8.23 2.29 <1 <1 2.78 N/A N/A
Se-Selenium(01147) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
TI-Thallium(01059) Ng/l <0.2 <0.2 <0.2 <0.2 <0.2 0.273 <0.2 <0.2 <0.2 N/A N/A
TDS-Total Dissolved Solids(70300) mg/I 110 170 300 320 230 220 180 360 500 54 53
TSS-Total Suspended Solids mg/l 38 8 <5 <5 <5 <5 <5 <5 <5 N/A N/A
pH S.U. 6.63 6.33 6.95 6.92 5.56 4.67 5.64 8.11 7.52 N/A N/A
Temperature °C 23.8 20.9 21.5 21.6 17.6 17.6 20.4 23.6 19 N/A N/A
Specific conductance NS/cm 107 229 447 524 326 341 222 555 717 N/A N/A
Flow MGD 0.0004 0.0025 0.0083 0.0008 0.0023 0.0002 0.0002 0.0002 0.0002 N/A N/A
Notes:
1. Flow measurements and analytical samples were collected on September 4 and 9, 2014.
2. WA indicates not applicable.
3. Lake Wylie samples were collected on August 27, 2014.
Appendix A-2

Appendix B
Sample Preservation and Hold Times
Appendix B-1

Parameter Name Container' Preservation z,3 Maximum 4
Holding Time
Table IB—Inorganic Tests
1. Acidity P, FP, G Cool, 56 OC14 days
2.Alkalinity P, FP, G Cool, 56°C16 14 days
4.Ammonia P, FP, G Cool, s6°C'J, H2SO4 to pH <2 28 days
9. Biochemical oxygen demand P, FP, G Cool, s6°C16 48 hours
10. Boron P, FP, or HNO3 to pH<2 6 months
Quartz
11. Bromide P, FP, G None required 28 days
14. Biochemical oxygen demand, P, FP G Cool, 56 °C'' 48 hours
carbonaceous
15.Chemical oxygen demand P, FP, G Cool, 56 00, H2SO4 to pH <2 28 days
16.Chloride P, FP, G None required 28 days
17. Chlorine,total residual P, G None required Analyze within 15
minutes
21. Color P, FP, G Cool, 56 0C16 48 hours
23-24. Cyanide,total or available P, FP, G Cool, 56 °C'', NaOH to pH 14 days
(or CATC)and free >105,6 reducing agent if oxidizer
present
25. Fluoride P None required 28 days
27. Hardness P, FP, G HNO3 or H2SO4to pH<2 6 months
28. Hydrogen ion(pH) P, FP, G None required Analyze within 15
minutes
31,43. Kjeldahl and organic N P, FP, G Cool, 56 00, H2SO4 to pH<2 28 days
Table IB—Metals?
18. Chromium VI P, FP, G Cool, 56 DO, pH =9.3-9.720 28 days
35. Mercury(CVAA) P, FP, G HNO3 to pH <2 28 days
35. Mercury(CVAFS) FP, G;and FP- 5 mUL 12N HCI or 5 mUL 90 days17
lined cap17 BrCl17
3, 5-8, 12, 13, 19,20,22,26,29, 30, P, FP, G HNO3 to pH <2, or at least 24 6 months
32-34, 36, 37,45,47, 51, 52, 58-60, hours prior to analysis19
62,63,70-72, 74,75. Metals,
except boron,chromium VI,and
mercury
38. Nitrate P, FP, G Cool, 56°C16 48 hours
39. Nitrate-nitrite P, FP, G Cool, 56°C16, H2SO4 to pH <2 28 days
40. Nitrite P, FP, G Cool, 56°C16 48 hours
41. Oil and grease IG Cool to 56 00, HCI or H2SO4 to 28 days
pH<2
Appendix B-2

Parameter Name Container' Preservation Z,3 Maximum 4
Holding Time
42.Organic Carbon P, FP, G Cool to 56 °C'', HCI, H2SO4, or 28 days
H3PO4 to pH <2
44.Orthophosphate P, FP, G Cool,to 56 °C'a'24 Filter within 15
minutes; analyze
within 48 hours
46. Oxygen, Dissolved Probe G, Bottle and None required Analyze within 15
top minutes
47.Winkler G, Bottle and Fix on site and store in dark 8 hours
top
48. Phenols G Cool, 56 00, H2SO4 to pH <2 28 days
49. Phosphorous(elemental) G Cool, 56°C'II 48 hours
50. Phosphorous,total P, FP, G Cool, s6°C13, H2SO4 to pH <2 28 days
53. Residue,total P, FP, G Cool, 56°C'' 7 days
54. Residue, Filterable P, FP, G Cool, 56°C'' 7 days
55. Residue, Nonfilterable(TSS) P, FP, G Cool, 56°C'a 7 days
56. Residue, Settleable P, FP, G Cool, 56 00' 48 hours
57. Residue,Volatile P, FP, G Cool, 56°C13 7 days
61. Silica P or Quartz Cool, <_6 °C'' 28 days
64. Specific conductance P, FP, G Cool, 56°C13 28 days
65. Sulfate P. FP, G Cool, s6°C" 28 days
66. Sulfide P, FP, G Cool, s6 °C'', add zinc acetate 7 days
plus sodium hydroxide to pH >9
67. Sulfite P, FP, G None required Analyze within 15
minutes
68. Surfactants P, FP, G Cool, 56 °C'' 48 hours
69.Temperature P, FP, G None required Analyze
73.Turbidity P, FP, G Cool, 56 °C'" 48 hours
Notes:
1. "P"is for polyethylene;"FP" is fluoropolymer(polytetrafluoroethylene(PTFE);Teflon®), or other
fluoropolymer, unless stated otherwise in this table; and"G" is glass.
2. Except where noted in this table and the method for the parameter, preserve each grab sample within 15
minutes of collection. For a composite sample collected with an automated sample(e.g., using a 24-hour
composite sample; see 40 CFR 122.21(gx7)(i)or 40 CFR Part 403, Appendix E), refrigerate the sample at
56°C during collection unless specified otherwise in this table or in the method(s). For a composite sample
to be split into separate aliquots for preservation and/or analysis, maintain the sample at 56 °C, unless
specified otherwise in this table or in the method(s), until collection, splitting, and preservation is completed.
Add the preservative to the sample container prior to sample collection when the preservative will not
compromise the integrity of a grab sample, a composite sample, or aliquot split from a composite sample
within 15 minutes of collection. If a composite measurement is required but a composite sample would
compromise sample integrity, individual grab samples must be collected at prescribed time intervals(e.g., 4
samples over the course of a day, at 6-hour intervals). Grab samples must be analyzed separately and the
concentrations averaged. Alternatively, grab samples may be collected in the field and composited in the
laboratory if the compositing procedure produces results equivalent to results produced by arithmetic
averaging of results of analysis of individual grab samples. For examples of laboratory compositing
Appendix B-3

procedures, see EPA Method 1664 Rev. A(oil and grease)and the procedures at 40 CFR 141.34(f)(14)(iv)
and (v)(volatile organics).
3. When any sample is to be shipped by common carrier or sent via the U.S. Postal Service, it must comply
with the Department of Transportation Hazardous Materials Regulations (49 CFR part 172).The person
offering such material for transportation is responsible for ensuring such compliance. For the preservation
requirement of this table, the Office of Hazardous Materials, Materials Transportation Bureau, Department of
Transportation has determined that the Hazardous Materials Regulations do not apply to the following
materials: Hydrochloric acid (HCI) in water solutions at concentrations of 0.04% by weight or less(pH about
1.96 or greater; Nitric acid(HNO3)in water solutions at concentrations of 0.15% by weight or less(pH about
1.62 or greater); Sulfuric acid (H2SO4) in water solutions at concentrations of 0.35% by weight or less(pH
about 1.15 or greater); and Sodium hydroxide(NaOH)in water solutions at concentrations of 0.080% by
weight or less(pH about 12.30 or less).
4. Samples should be analyzed as soon as possible after collection.The times listed are the maximum times
that samples may be held before the start of analysis and still be considered valid. Samples may be held for
longer periods only if the permittee or monitoring laboratory has data on file to show that,for the specific
types of samples under study, the analytes are stable for the longer time, and has received a variance from
the Regional Administrator under Sec. 136.3(e). For a grab sample, the holding time begins at the time of
collection. For a composite sample collected with an automated sampler(e.g., using a 24-hour composite
sampler; see 40 CFR 122.21(g)(7)(i)or 40 CFR part 403,Appendix E), the holding time begins at the time of
the end of collection of the composite sample. For a set of grab samples composited in the field or
laboratory, the holding time begins at the time of collection of the last grab sample in the set. Some samples
may not be stable for the maximum time period given in the table. A permittee or monitoring laboratory is
obligated to hold the sample for a shorter time if it knows that a shorter time is necessary to maintain sample
stability. See 136.3(e)for details.The date and time of collection of an individual grab sample is the date
and time at which the sample is collected. For a set of grab samples to be composited, and that are all
collected on the same calendar date, the date of collection is the date on which the samples are collected.
For a set of grab samples to be composited, and that are collected across two calendar dates,the date of
collection is the dates of the two days; e.g., November 14-15. For a composite sample collected
automatically on a given date,the date of collection is the date on which the sample is collected. For a
composite sample collected automatically, and that is collected across two calendar dates, the date of
collection is the dates of the two days; e.g., November 14-15. For static-renewal toxicity tests, each grab or
composite sample may also be used to prepare test solutions for renewal at 24 h, 48 h, and/or 72 h after
first use, if stored at 0-6 °C, with minimum head space.
5. ASTM D7365-09a species treatment options for samples containing oxidants(e.g., chlorine).Also, Section
9060A of Standard Methods for the Examination of Water and Wastewater(20th and 21 st editions)
addresses dechlorination procedures.
6. Sampling, preservation and mitigating interferences in water samples for analysis of cyanide are described
in ASTM D7365-09a.There may be interferences that are not mitigated by the analytical test methods or
D7365-09a.Any technique for removal or suppression of interference may be employed, provided the
laboratory demonstrates that it more accurately measures cyanide through quality control measures
described in the analytical test method.Any removal or suppression technique not described in D7365-09a
or the analytical test method must be documented along with supporting data.
7. For dissolved metals,filter grab samples within 15 minutes of collection and before adding preservatives.
For a composite sample collected with an automated sampler(e.g., using a 24-hour composite sampler; see
40 CFR 122.21(g)(7)(i)or 40 CFR Part 403, Appendix E), filter the sample within 15 minutes after
completion of collection and before adding preservatives. If it is known or suspected that dissolved sample
integrity will be compromised during collection of a composite sample collected automatically over time
(e.g., by interchange of a metal between dissolved and suspended forms), collect and filter grab samples to
be composited (footnote 2)in place of a composite sample collected automatically.
8. Guidance applies to samples to be analyzed by GC, LC, or GC/MS for specific compounds.
9. If the sample is not adjusted to pH 2, then the sample must be analyzed within seven days of sampling.
10. The pH adjustment is not required if acrolein will not be measured. Samples for acrolein receiving no pH
adjustment must be analyzed within 3 days of sampling.
11. When the extractable analytes of concern fall within a single chemical category, the specified preservative
and maximum holding times should be observed for optimum safeguard of sample integrity(i.e., use all
necessary preservatives and hold for the shortest time listed).When the analytes of concern fall within two
or more chemical categories, the sample may be preserved by cooling to s6°C, reducing residual chlorine
with 0.008% sodium thiosulfate, storing in the dark, and adjusting the pH to 6-9; samples preserved in this
manner may be held for seven days before extraction and for forty days after extraction. Exceptions to this
optional preservation and holding time procedure are noted in footnote 5(regarding the requirement for
Appendix B-4

thiosulfate reduction), and footnotes 12, 13(regarding the analysis of benzidine).
12. If 1,2-diphenylhydrazine is likely to be present, adjust the pH of the sample to 4.0 t0.2 to prevent
rearrangement to benzidine.
13. Extracts may be stored up to 30 days at<0 °C.
14. For the analysis of diphenylnitrosamine, add 0.008% Na2S2O3 and adjust pH to 7-10 with NaOH within 24
hours of sampling.
15. The pH adjustment may be performed upon receipt at the laboratory and may be omitted if the samples are
extracted within 72 hours of collection. For the analysis of aldrin, add 0.008% Na2S2O3.
16. Place sufficient ice with the samples in the shipping container to ensure that ice is still present when the
samples arrive at the laboratory. However, even if ice is present when the samples arrive, immediately
measure the temperature of the samples and confirm that the preservation temperature maximum has not
been exceeded. In the isolated cases where it can be documented that this holding temperature cannot be
met, the permittee can be given the option of on-site testing or can request a variance.The request for a
variance should include supportive data which show that the toxicity of the effluent samples is not reduced
because of the increased holding temperature.Aqueous samples must not be frozen. Hand-delivered
samples used on the day of collection do not need to be cooled to 0 to 6 °C prior to test initiation.
17. Samples collected for the determination of trace level mercury(<100 ng/L)using EPA Method 1631 must be
collected in tightly-capped fluoropolymer or glass bottles and preserved with BrCI or HCI solution within 48
hours of sample collection. The time to preservation may be extended to 28 days if a sample is oxidized in
the sample bottle.A sample collected for dissolved trace level mercury should be filtered in the laboratory
within 24 hours of the time of collection. However, if circumstances preclude overnight shipment, the sample
should be filtered in a designated clean area in the field in accordance with procedures given in Method
1669. If sample integrity will not be maintained by shipment to and filtration in the laboratory, the sample
must be filtered in a designated clean area in the field within the time period necessary to maintain sample
integrity.A sample that has been collected for determination of total or dissolved trace level mercury must
be analyzed within 90 days of sample collection.
18. Aqueous samples must be preserved at s6 °C, and should not be frozen unless data demonstrating that
sample freezing does not adversely impact sample integrity is maintained on file and accepted as valid by
the regulatory authority. Also,for purposes of NPDES monitoring, the specification of"s°C" is used in place
of the"4°C"and "<4 °C"sample temperature requirements listed in some methods. It is not necessary to
measure the sample temperature to three significant figures (1/100th of 1 degree); rather, three significant
figures are specified so that rounding down to 6 °C may not be used to meet the 56 °C requirement.The
preservation temperature does not apply to samples that are analyzed immediately(less than 15 minutes).
19. An aqueous sample may be collected and shipped without acid preservation. However, acid must be added
at least 24 hours before analysis to dissolve any metals that adsorb to the container walls. If the sample
must be analyzed within 24 hours of collection, add the acid immediately(see footnote 2). Soil and sediment
samples do not need to be preserved with acid.The allowances in this footnote supersede the preservation
and holding time requirements in the approved metals methods.
20. To achieve the 28-day holding time, use the ammonium sulfate buffer solution specked in EPA Method
218.6.The allowance in this footnote supersedes preservation and holding time requirements in the
approved hexavalent chromium methods, unless this supersession would compromise the measurement, in
which case requirements in the method must be followed.
21. Holding time is calculated from time of sample collection to elution for samples shipped to the laboratory in
bulk and calculated from the time of sample filtration to elution for samples filtered in the field.
22. Sample analysis should begin as soon as possible after receipt; sample incubation must be started no later
than 8 hours from time of collection.
23. For fecal coliform samples for sewage sludge(biosolids)only, the holding time is extended to 24 hours for
the following sample types using either EPA Method 1680(LTB-EC)or 1681 (A-1): Class A composted,
Class B aerobically digested, and Class B anaerobically digested.
24. The immediate filtration requirement in orthophosphate measurement is to assess the dissolved or bio-
available form of orthophosphorus(i.e., that which passes through a 0.45-micron filter), hence the
requirement to filter the sample immediately upon collection(i.e., within 15 minutes of collection). [38 FR
28758, Oct. 16, 1973].
Appendix B-5

Appendix C
Description of Engineered Drainage Systems for Earthen Dams
At the Allen Steam Ash Basin
Appendix C-1

Description of Engineered Drainage Systems for Earthen Dams at the Allen Active Ash Basin
All earth dams are subject to seepage through the embankment,foundation, and abutments. Seepage control
is necessary to prevent excessive uplift pressures, instability of the downstream slope, piping through the
embankment and/or foundation, and erosion of material by migration into open joints in the foundation and
abutments. The control of seepage is performed by the use of engineered drains such as blanket drains,trench
drains, and/or toe drains. In certain cases horizontal pipes may be installed into the embankment to collect and
control seepage. It is standard engineering practice to collect and convey seepage away from the dam.
The text below provides a description of the engineered drainage systems for the active ash basin dams.
GASTO-061 Allen Active Ash Basin Dam
The Allen active ash basin dam consists of an embankment oriented approximately east-to-west, referred to as
the north dike, and an embankment oriented approximately north-to-south, along the Catawba River, referred to
as the east dam.
The east dam was not constructed with any internal seepage drains at the foundation.As shown on Duke
drawing A-3550-2, revision 3, section M-M, a drainage system consisting of washed stone encased in filter
fabric was installed on the north slope of this dike with the top at elevation 627 feet(approximate). The drainage
system terminates at a toe drain which is covered by filter fabric and#67 stone.
The north dam embankment was originally constructed in 1973. In 1982 an additional berm was constructed to
elevation 620 feet against the downstream slope of the original 1973 embankment.The drainage system for the
original 1973 embankment consists of a zoned trench drain, a zoned ladder drain with perforated pipe, and a
zoned blanket drain as shown on drawing A-3350-1 A, revision 19, section C-C.This drainage system was
installed where the embankment foundation elevation was between 575.0 feet to 600.0 feet.
The zoned trench drain and zoned ladder drain with perforated pipe extend from the downstream toe of the
1973 embankment towards the center of the dam, covering the downstream 1/3 of the embankment foundation.
The ladder drains consist of trenches or raised drains filled with a minimum of 12-inches of coarse filter material
surrounded by minimum 9-inch thick layer of fine filter material.A 4-inch diameter perforated pipe is located in
the center of the coarse filter material.These trenches(or raised drains)are spaced at 50 foot centers and are
oriented perpendicular to the zoned trench drain, which is located at the upstream end of the ladder drain. The
trench drain consists of a trench excavated below the foundation grade 4-foot 6 inches deep and filled with a
minimum width of 2-feet of coarse filter material. The coarse filter is surrounded by a minimum 10-inch-thick
layer of fine filter material.A blanket drain of 9-inches of fine filter material is continuous across and between the
ladder trenches or drains of the ladder drain system.
The north dam has a zoned blanket drain and a zoned toe drain constructed under the portions of the dike
constructed in 1982. The zoned blanket drain was constructed to be continuous with the downstream end of the
drainage system constructed under the 1973 embankment. The zoned blanket drain consists of a 12-inch thick
layer of coarse filter material surrounded by 9-inch thick layers of fine filter material above and below the coarse
filter.
The zoned toe drain was constructed where the foundation elevation was from 600 feet to 615 feet(Duke
drawing A-3550-1A Revision 19, Section 13-6). The zoned drainage blanket terminates into the zoned toe drain
and consists of unclassified rip-rap, surrounded by filter fabric, placed underneath the extension of the drainage
blanket. The final cover for the zoned toe drain is 15-inches of type C rip-rap.
Appendix C-2

ALLEN sTEAm
NPIDES 001NPOES 114
STATION
2 s
AS-lR PLANT ALLEN
• N
INACTIVE
ASH BASIN
DUKE ENERGY PROPER rY ASH STORA
INACTIVE RETIRED ASH 13ASIN
ASH BASIN ASH STORAGE ASH LANDFILL
PERMIT NO.3612
RIVER RIJN
AB-14D Ar AB-9S
IF IIAB
•1
• -
IKE
THNOLAKE W"YLIE
1
IFARMS •
AB-4 Uj
LEGEND:
� DUKE ENERGY PROPERTY BOUNDARY
ACTIVE ASH BASIN S-6 ASH BASIN WASTE BOUNDARY
ASH STORAGE AREA BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
1 COINCIDENT WITH DUKE PROPERTY BOUNDARY
1/ .. . - — STREAM
Woo•_; ► •' DISCHARGE TOWER --–––– TOPOGRAPHIC CONTOUR(4-FT INTERVAL)
NPDES 002
ASH BASIN COMPLIANCE GROUNDWATER
•* MONITORING WELL
•
• SEEP SAMPLE LOCATION
. NPDES OUTFALL LOCATION
•
•
•'
NOTES: IDENTIFIED SEEPS AND WATER QUALITY
�oo� SCALE (FEET)Ll DATE
1.PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE. SAMPLE LOCATION MAP OCTOBER 2014
2.WASTE BOUNDARY IS APPROXIMATE. B00'
3.AS-BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP. DUKE ENERGY CAROLINAS, LLC
4.TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM(GIS)WEB SITE(DATED 2007). ALLEN STEAM STATION ASH BASIN FIGURE
S.AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 17,2014. F)l
6.THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 15A NCACO2L.0107(a). GASTON COUNTY, NORTH CAROLINA 1
7.SEEP SAMPLING LOCATIONS ARE APPROXIMATE.
S.NPDES OUTFALL LOCATIONS PROVIDED BY DUKE ENERGY. NPDES PERMIT#NC0004979
9.SEE REPORT"ALLEN STEAM STATION ASH BASIN SURFACE WATER AND SEEP MONITORING-OCTOBER 2014,APPENDIX C"FOR DESCRIPTION OF DAM DRAINAGE SYSTEM.

Attachment 1
Allen Steam Station
NC0004979
Toe drain information

Allen Steam Station
Ash Basin Surface Water and Seep Monitoring
August and September 2014
Introduction
Flow and water quality measurements were collected from nine seep sampling locations (S-1 through S-
9)and two surface water locations near the ash basin (Lake Wylie-Upstream and Lake Wylie-
Downstream)associated with Duke Energy's Allen Steam Station, located in Gaston County, North
Carolina.The purpose of the sampling, which was conducted in late August and early September 2014,
was to measure seepage flows and provide sufficient depth to allow collection of water quality samples for
laboratory analysis. Samples were collected via a combination of methods as described below. See
Figures 1 and 2 for maps of the approximate sampling locations. Descriptions of the seep sampling
locations are provided in Table 1.
A description of the engineering drainage systems for earthen dams at the Cliffside Steam Station Ash
Basin is located in Appendix C.
Seep Flow Measurement Method and Results
A V-notch weir apparatus was utilized at locations S-1, S-2, S-3, and S-4 to impound the seepage in a
channel, which concentrated discharge to a central location that allowed for flow measurements to be
obtained.The weirs were constructed from %-inch-thick Plexiglas board material. Each device was
inspected after installation and prior to sampling to confirm sufficient flow and depth for sampling, and to
verify that only minimal leakage, if any, was present. Sufficient time was allowed for the impounded
seepage flows to reach equilibrium discharge flow before flow measurement and sampling.
Flow measurements at seep sampling locations S-5, S-6, and S-7 were collected by installing a 2-inch-
diameter PVC pipe into the ground surface where the seep emerged. Seepage in these locations was
diffuse, with no defined channel. Each PVC pipe was inserted in the location to direct flow through the
pipe. Flow from the pipe was observed until the discharge appeared to be clear of visible fines prior to
sampling for water quality analysis.
Flow measurements at locations S-8 and S-9 were collected from two outfalls consisting of 12-inch-
diameter corrugated metal pipes(CMP). Based on a conversation with Duke Energy personnel familiar
with the site, the source of water discharging from these pipes is unknown. These outfalls exhibited flow
during a dry-weather visual assessment consisting of least 72 hours prior to a rainfall event.The source
of persistent flow from these outfalls is assumed to be groundwater and not stormwater.
The seepage flows at locations S-1 through S-9 were measured using the timed-volumetric method. A
volume of water was collected from the discharge of the weir directly into an appropriately sized container.
Volumes(in mL)were measured in the field utilizing a graduated container.The amount of time(in
seconds)needed to collect the volume of water was recorded and flows(in MGD)were calculated for the
timed-volume. The calculated flows(in MGD)at each seep location are presented in Appendix A.
Seep Water Quality Sample Collection Method and Results
Water quality samples were collected at locations S-1 through S-9.To minimize potential effects of
stormwater runoff, seep samples were collected during a period with minimal preceding rainfall. Samples
were collected from the discharge flow at the flow measurement devices described above or directly
1

from the seep into sample bottles while minimizing disturbance and entrainment of soil/sediment.
Analytical parameters for analysis were: TSS,TDS, Oil &Grease, Cl, SO4, F, COD,Al, As, B, Ba, Ca, Cd,
Cu, Cr, Fe, Mn, Mo, Mg, Ni, Pb, Sb, Se, TI, Zn, Hardness, and Hg. Storage and preservation techniques
of the samples, after collection and prior to analyses, were followed according to Appendix B.Analyses
were conducted by Duke Energy's Huntersville analytical laboratory(NC Wastewater Certification#248)
and Pace Analytical Laboratories(NC Wastewater Certification#12). Laboratory analytical methods used
for each parameter are provided in Table 2 and analytical results are presented in Appendix A.
Seep In-situ Measurement Method and Results
In-situ field parameters(temperature, pH, and specific conductance)were measured at locations S-1
through S-9 utilizing calibrated field meters either at the discharge of the seep directly, at the discharge of
the flow measurement devices, or in the water pool created behind the device, if sufficient water depth did
not exist at the device discharge.The analytical results are presented in Appendix A.
Lake Wylie Water Quality and In-situ Sample Collection Method and Results
Water quality samples and in-situ measurements from were collected at a location upstream (Lake Wylie-
Upstream) and downstream (Lake Wylie-Downstream)of the ash basin (Figure 2).The grab samples
were collected from the surface(0.3 m)directly into appropriate sample bottles. Preservation and
analyses methods for the lake samples are provided in Table 2 and Appendix B.The analytical results are
presented in Appendix A.
Recommendations
The low volume of flow at each seep location, coupled with the relatively low constituent concentrations in
the samples, suggests that there is little potential for Allen Steam Station to influence water quality in Lake
Wylie. If reasonable potential analyses demonstrate that there is no potential to exceed water quality
standards, then Duke Energy proposes to re-evaluate the seep locations listed in this document annually
over the next 5-year permit cycle.These annual evaluations would be documented and would verify the
condition of the existing seeps and determine the presence of new seeps.
The North Carolina Department of Environment and Natural Resources—Division of Water Resources
(DWR)will be promptly notified if any new seeps are identified or any significant changes are observed
for the existing seeps. If any existing or newly identified seeps are determined to reach Lake Wylie, and
demonstrate reasonable potential to exceed a water quality standard, Duke Energy will do one of the
following: 1)stop the seep, 2)capture and route the seep so that it is discharged through a National
Pollutant Discharge Elimination System (NPDES) permitted outfall, or 3)address the seep using Best
Management Plans approved by DWR.
Most of the analytical results upstream and downstream of the ash basin discharge in Lake Wylie with the
exception of copper and zinc are at, or near, the method detection limits and below limits for water quality
standards. Measured values at these two locations are consistent with historical data from previous
monitoring efforts in Lake Wylie. Duke Energy proposes that the semi-annual in-stream monitoring
frequency be maintained.
2

Table 1 —Allen Steam Station Surface Water/Seep Locations and Descriptions
Seep Location Coordinates' Flow
ID Latitude Longitude Description Seep Description
S-1 35°10.242' 81 00.625' Continuous Located south of Active Ash Basin, north of Nutall Oak Lane.Tributary towards Lake
Wylie.Well-defined stream approximately 3-ft wide.
S-2 35010.426' 8100.344' Continuous Located southeast of Active Ash Basin.Tributary towards Lake Wylie.Well-defined
stream approximately 1-ft wide.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-3 35010.513' 8100.360' Continuous approximately 2-ft wide. Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-4 35010.513' 8100.360' Continuous approximately 1.5-ft wide. Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
S-5 35010.621' 81°0.366' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-6 35010.626' 8100.369' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-7 35010.664' 8100.380' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-8 35010.706' 8100.391' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
S-9 35011.146' 8100.394' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
Notes:
1. Location coordinates(degrees)for seep sampling locations are approximate, and are in NAD 83 datum.
2. Flow description for each seep sample location is based on observation during site visits performed by HDR Engineering, Inc. (HDR)on August
21, 2014. Flow measurements and analytical samples were collected on September 4 and September 9, 2014.
3

Table 2—Laboratory Analytical Methods
Parameter Method ReportingLimit Units Laboratory
Chemical Oxygen HACH 8000 20 mg/L Duke Energy
Demand COD
Chloride(CI) EPA 300.0 1 mg/L Duke Energy
Fluoride(FI) EPA 300.0 1 mg/L Duke Energy
Sulfate(SO4) EPA 300.0 1 mg/L Duke Energy
Oil and Grease EPA 16646 5 ug/L Pace Analtyical
Mercury(Hg) EPA 245.1 0.05 ug/L Duke Energy
Aluminum(AI) EPA 200.7 0.005 mg/L Duke Energy
Barium(Ba) EPA 200.7 0.005 mg/L Duke Energy
Boron(B) EPA 200.7 0.05 mg/L Duke Energy
Calcium (Ca) EPA 200.7 0.01 mg/L Duke Energy
Hardness EPA 200.7 0.19 mg/L(CaCO3) Duke Energy
Iron (Fe) EPA 200.7 0.01 mg/L Duke Energy
Magnesium (Mg) EPA 200.7 0.005 mg/L Duke Energy
Manganese(Mn) EPA 200.7 0.005 mg/L Duke Energy
Zinc(Zn) EPA 200.7 0.005 mg/L Duke Energy
Antimony(Sb) EPA 200.8 1 ug/L Duke Energy
Arsenic(As) EPA 200.8 1 ug/L Duke Energy
Cadmium(Cd) EPA 200.8 1 ug/L Duke Energy
Chromium(Cr) EPA 200.8 1 ug/L Duke Energy
Copper(Cu) EPA 200.8 1 mg/L Duke Energy
Lead (Pb) EPA 200.8 1 ug/L Duke Energy
Molybdenum (Mo) EPA 200.8 1 ug/L Duke Energy
Nickel (Ni) EPA 200.8 1 ug/L Duke Energy
Selenium(Se) EPA 200.8 1 ug/L Duke Energy
Thallium (TI)Low Level EPA 200.8 0.2 ug/L Duke Energy
TDS SM2540C 25 mg/L Duke Energy
TSS SM2540D 5 mg/L Duke Energy
4

Appendix A
Seep Flows and Analytical Results
Appendix A-1

Allen Steam Station
Surface Water/Seep Monitoring Analytical Results-September 2014
Parameter Units Lake Wylie- Lake W
Seep Monitoring Location Wylie-
S-1 S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 Upstream2,3 Downstream2,3
Oil&Grease mg/I <5 <5 <5.0 <5 <5 <5.0 <5 <5 <5 N/A N/A
COD-Chemical Oxygen Demand mg/I <20 <20 20 <20 <20 <20 <20 <20 <20 N/A N/A
Cl-Chloride(00940) mg/I 4.3 49 32 41 59 62 7.8 7.5 9.1 N/A N/A
FI-Fluoride mg/I 0.11 0.1 0.13 <0.1 <0.1 0.11 <0.1 0.17 <0.5 N/A N/A
SO4-Sulfate(00945) mg/I 1.4 10 26 21 42 55 74 87 180 N/A N/A
Hg- Mercury(71900) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Al -Aluminum(01105) mg/I 0.996 0.467 0.039 0.022 <0.005 0.21 0.083 0.01 0.254 WA N/A
Ba- Barium (01007) mg/I 0.044 0.114 0.044 0.047 0.208 0.307 0.057 0.060 0.029 N/A N/A
B-Boron (01022) mg/I <0.05 0.871 0.555 0.713 0.927 1.01 0.934 0.606 1.49 N/A N/A
Ca-Calcium mg/I 7.34 7.25 61.7 73.4 20.7 19.8 17.8 97.6 138 N/A N/A
Hardness mg/I(CaCO3) 31.9 74.4 203 251 111 112 76 292 413 N/A WA
Fe-Iron (01045) mg/I 1.86 1.25 0.136 0.215 <0.01 0.015 0.113 0.011 0.942 N/A N/A
Mg-Magnesium mg/I 3.29 13.7 12 16.4 14.4 15.2 7.69 11.7 16.5 N/A N/A
Mn-Manganese(01055) mg/I 0.356 0.305 0.131 0.310 1.45 2.25 0.395 <0.005 0.998 N/A N/A
Zn-Zinc(01092) mgA <0.005 <0.005 <0.005 <0.005 0.011 <0.005 <0.005 <0.005 0.283 3.08 <2
Sb-Antimony(01097) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 NIA N/A
As-Arsenic(01002) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cd-Cadmium (01027) Ng/1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cr-Chromium(01034) pwi 1.42 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cu-Copper(01042) pg/l <1 <1 <1 <1 <1 1.14 <1 <1 1.31 2.80 2.60
Pb-Lead(01051) NgA <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Mo-Molybdenum Ng/1 <1 <1 <1 <1 <1 <1 <1 <1 <1 N/A WA
NI-Nickel(01067) Ng/I <1 1.58 <1 <1 8.23 2.29 <1 <1 2.78 N/A WA
Se-Selenium (01147) Ng/l <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
TI-Thallium(01059) Ng/l <0.2 <0.2 <0.2 <0.2 <0.2 0.273 <0.2 <0.2 <0.2 N/A N/A
TDS-Total Dissolved Solids(70300) mg/I 110 170 300 320 230 220 180 360 500 54 53
TSS-Total Suspended Solids mg/I 38 8 <5 <5 <5 <5 <5 <5 <5 N/A N/A
pH s.u. 6.63 6.33 6.95 6.92 5.56 4.67 5.64 8.11 7.52 N/A N/A
Temperature °C 23.8 20.9 21.5 21.6 17.6 17.6 20.4 23.6 19 N/A WA
Specific conductance NS/cm 107 229 447 524 326 341 222 555 717 N/A N/A
Flow MGD 0.0004 0.0025 0.0083 0.0008 0.0023 0.0002 0.0002 0.0002 0.0002 N/A N/A
Notes:
1. Flow measurements and analytical samples were collected on September 4 and 9, 2014.
2. N/A indicates not applicable.
3. Lake Wylie samples were collected on August 27, 2014.
Appendix A-2

Appendix B
Sample Preservation and Hold Times
Appendix B-1

Parameter Name Container' Preservation 2,3 Maximum 4
Holding Time
Table IB—Inorganic Tests
1.Acidity P, FP, G Cool, 56`C15 14 days
2.Alkalinity P, FP, G Cool, 56°C1tl 14 days
4. Ammonia P, FP, G Cool, 56°C1", H2SO4 to pH <2 28 days
9. Biochemical oxygen demand P, FP, G Cool, s6°C15 48 hours
10. Boron P, FP, or HNO3 to pH <2 6 months
Quartz
11. Bromide P, FP, G None required 28 days
14. Biochemical oxygen demand, P, FP G Cool, 56°C1" 48 hours
carbonaceous
15. Chemical oxygen demand P, FP, G Cool, 56°C18, H2SO4 to pH <2 28 days
16. Chloride P, FP, G None required 28 days
17. Chlorine,total residual P, G None required Analyze within 15
minutes
21. Color P, FP, G Cool, 56°C1a 48 hours
23-24. Cyanide,total or available P, FP, G Cool, 56°C'", NaOH to pH 14 days
(or CATC)and free >105,6 reducing agent if oxidizer
present
25. Fluoride P None required 28 days
27. Hardness P, FP, G HNO3 or H2SO4to pH<2 6 months
28. Hydrogen ion (pH) P, FP, G None required Analyze within 15
minutes
31,43. Kjeldahl and organic N P. FP, G Cool, s6 OC"', H2SO4 to pH <2 28 days
Table IB—Metals
18.Chromium VI P, FP, G Cool, 56°C18, pH =9.3-9.720 28 days
35. Mercury(CVAA) P, FP, G HNO3 to pH <2 28 days
35. Mercury(CVAFS) FP, G; and FP- 5 mUL 12N HCI or 5 mUL 90 days17
lined cap17 BrCI"
3, 5-8, 12, 13, 19, 20,22, 26,29, 30, P, FP, G HNO3 to pH<2, or at least 24 6 months
32-34, 36, 37,45, 47, 51, 52, 58-60, hours prior to analysis19
62, 63, 70-72, 74, 75. Metals,
except boron, chromium VI,and
mercury
38. Nitrate P, FP, G Cool, 56°C15 48 hours
39. Nitrate-nitrite P, FP, G Cool, s6°C15, H2SO4 to pH <2 28 days
40. Nitrite P, FP, G Cool, 56 00' 48 hours
41.Oil and grease G Cool to 56 00, HCl or H2SO4 to 28 days
pH<2
Appendix B-2

Parameter Name Container' Preservation 2,3 Maximum 4
Holding Time
42.Organic Carbon P, FP, G Cool to 56 °C", HCI, H2SO4, or 28 days
H3PO4 to pH <2
44.Orthophosphate P, FP, G Cool, to 56 °C'"'24 Filter within 15
minutes; analyze
within 48 hours
46.Oxygen, Dissolved Probe G, Bottle and None required Analyze within 15
top minutes
47.Winkler G, Bottle and Fix on site and store in dark 8 hours
top
48. Phenols G Cool, 56 °C'", H2SO4 to pH <2 28 days
49. Phosphorous(elemental) G Cool, s6°C" 48 hours
50. Phosphorous,total P, FP, G Cool, 56°C", H2SO4 to pH <2 28 days
53. Residue,total P, FP, G Cool, 56 °C" 7 days
54. Residue, Filterable P, FP, G Cool, 56°C" 7 days
55. Residue, Nonfilterable(TSS) P, FP, G Cool, 56 °C" 7 days
56. Residue, Settleable P, FP, G Cool, 56 °C", 48 hours
57. Residue,Volatile P, FP, G Cool, 56°C" 7 days
61. Silica P or Quartz Cool, s6°C'" 28 days
64. Specific conductance P, FP, G Cool, 56°C" 28 days
65. Sulfate P, FP, G Cool, 56°C" 28 days
66.Sulfide P, FP, G Cool, 56°C'", add zinc acetate 7 days
plus sodium hydroxide to pH >9
67. Sulfite P, FP, G None required Analyze within 15
minutes
68. Surfactants P FP G Cool 56°C" 48 hours
69.Temperature P, FP, G None required Analyze
73.Turbidity P, FP, G Cool, 56'C'" 48 hours
Notes:
1. "P"is for polyethylene; "FP"is fluoropolymer(polytetrafluoroethylene(PTFE);Teflon®), or other
fluoropolymer, unless stated otherwise in this table; and"G" is glass.
2. Except where noted in this table and the method for the parameter, preserve each grab sample within 15
minutes of collection. For a composite sample collected with an automated sample(e.g., using a 24-hour
composite sample; see 40 CFR 122.21(g)(7)(i)or 40 CFR Part 403, Appendix E), refrigerate the sample at
56'C during collection unless specified otherwise in this table or in the method(s). For a composite sample
to be split into separate aliquots for preservation and/or analysis, maintain the sample at 56°C, unless
specified otherwise in this table or in the method(s), until collection, splitting, and preservation is completed.
Add the preservative to the sample container prior to sample collection when the preservative will not
compromise the integrity of a grab sample,a composite sample, or aliquot split from a composite sample
within 15 minutes of collection. If a composite measurement is required but a composite sample would
compromise sample integrity, individual grab samples must be collected at prescribed time intervals(e.g., 4
samples over the course of a day, at 6-hour intervals). Grab samples must be analyzed separately and the
concentrations averaged.Alternatively, grab samples may be collected in the field and composited in the
laboratory if the compositing procedure produces results equivalent to results produced by arithmetic
averaging of results of analysis of individual grab samples. For examples of laboratory compositing
Appendix B-3

procedures, see EPA Method 1664 Rev. A(oil and grease)and the procedures at 40 CFR 141.34(f)(14)(iv)
and (v)(volatile organics).
3. When any sample is to be shipped by common carrier or sent via the U.S. Postal Service, it must comply
with the Department of Transportation Hazardous Materials Regulations(49 CFR part 172).The person
offering such material for transportation is responsible for ensuring such compliance. For the preservation
requirement of this table, the Office of Hazardous Materials, Materials Transportation Bureau, Department of
Transportation has determined that the Hazardous Materials Regulations do not apply to the following
materials: Hydrochloric acid (HCI) in water solutions at concentrations of 0.04% by weight or less(pH about
1.96 or greater; Nitric acid (HNO3)in water solutions at concentrations of 0.15% by weight or less(pH about
1.62 or greater); Sulfuric acid (H2SO4)in water solutions at concentrations of 0.35% by weight or less(pH
about 1.15 or greater); and Sodium hydroxide(NaOH)in water solutions at concentrations of 0.080% by
weight or less(pH about 12.30 or less).
4. Samples should be analyzed as soon as possible after collection. The times listed are the maximum times
that samples may be held before the start of analysis and still be considered valid. Samples may be held for
longer periods only if the permittee or monitoring laboratory has data on file to show that,for the specific
types of samples under study, the analytes are stable for the longer time, and has received a variance from
the Regional Administrator under Sec. 136.3(e). For a grab sample, the holding time begins at the time of
collection. For a composite sample collected with an automated sampler(e.g., using a 24-hour composite
sampler; see 40 CFR 122.21(g)(7)(i)or 40 CFR part 403, Appendix E), the holding time begins at the time of
the end of collection of the composite sample. For a set of grab samples composited in the field or
laboratory, the holding time begins at the time of collection of the last grab sample in the set. Some samples
may not be stable for the maximum time period given in the table. A permittee or monitoring laboratory is
obligated to hold the sample for a shorter time if it knows that a shorter time is necessary to maintain sample
stability. See 136.3(e)for details.The date and time of collection of an individual grab sample is the date
and time at which the sample is collected. For a set of grab samples to be composited, and that are all
collected on the same calendar date, the date of collection is the date on which the samples are collected.
For a set of grab samples to be composited, and that are collected across two calendar dates, the date of
collection is the dates of the two days; e.g., November 14-15. For a composite sample collected
automatically on a given date, the date of collection is the date on which the sample is collected. For a
composite sample collected automatically, and that is collected across two calendar dates, the date of
collection is the dates of the two days; e.g., November 14-15. For static-renewal toxicity tests, each grab or
composite sample may also be used to prepare test solutions for renewal at 24 h, 48 h, and/or 72 h after
first use, if stored at 0-6°C, with minimum head space.
5. ASTM D7365-09a specifies treatment options for samples containing oxidants(e.g., chlorine).Also, Section
9060A of Standard Methods for the Examination of Water and Wastewater(20th and 21 st editions)
addresses dechlorination procedures.
6. Sampling, preservation and mitigating interferences in water samples for analysis of cyanide are described
in ASTM D7365-09a. There may be interferences that are not mitigated by the analytical test methods or
D7365-09a.Any technique for removal or suppression of interference may be employed, provided the
laboratory demonstrates that it more accurately measures cyanide through quality control measures
described in the analytical test method.Any removal or suppression technique not described in D7365-09a
or the analytical test method must be documented along with supporting data.
7. For dissolved metals,filter grab samples within 15 minutes of collection and before adding preservatives.
For a composite sample collected with an automated sampler(e.g., using a 24-hour composite sampler; see
40 CFR 122.21(g)(7)(i)or 40 CFR Part 403, Appendix E),filter the sample within 15 minutes after
completion of collection and before adding preservatives. If it is known or suspected that dissolved sample
integrity will be compromised during collection of a composite sample collected automatically over time
(e.g., by interchange of a metal between dissolved and suspended forms), collect and filter grab samples to
be composited (footnote 2) in place of a composite sample collected automatically.
8. Guidance applies to samples to be analyzed by GC, LC, or GC/MS for specific compounds.
9. If the sample is not adjusted to pH 2, then the sample must be analyzed within seven days of sampling.
10. The pH adjustment is not required if acrolein will not be measured. Samples for acrolein receiving no pH
adjustment must be analyzed within 3 days of sampling.
11. When the extractable analytes of concern fall within a single chemical category, the specified preservative
and maximum holding times should be observed for optimum safeguard of sample integrity(i.e., use all
necessary preservatives and hold for the shortest time listed).When the analytes of concern fall within two
or more chemical categories, the sample may be preserved by cooling to s6 °C, reducing residual chlorine
with 0.008% sodium thiosulfate, storing in the dark, and adjusting the pH to 6-9; samples preserved in this
manner may be held for seven days before extraction and for forty days after extraction. Exceptions to this
optional preservation and holding time procedure are noted in footnote 5(regarding the requirement for
Appendix B-4

thiosulfate reduction), and footnotes 12, 13(regarding the analysis of benzidine).
12. If 1,2-diphenylhydrazine is likely to be present, adjust the pH of the sample to 4.0 t0.2 to prevent
rearrangement to benzidine.
13. Extracts may be stored up to 30 days at<0 °C.
14. For the analysis of diphenyinitrosamine, add 0.008% Na2S2O3 and adjust pH to 7-10 with NaOH within 24
hours of sampling.
15. The pH adjustment may be performed upon receipt at the laboratory and may be omitted if the samples are
extracted within 72 hours of collection. For the analysis of aldrin, add 0.008% Na2S203.
16. Place sufficient ice with the samples in the shipping container to ensure that ice is still present when the
samples arrive at the laboratory. However, even if ice is present when the samples arrive, immediately
measure the temperature of the samples and confirm that the preservation temperature maximum has not
been exceeded. In the isolated cases where it can be documented that this holding temperature cannot be
met, the permittee can be given the option of on-site testing or can request a variance.The request for a
variance should include supportive data which show that the toxicity of the effluent samples is not reduced
because of the increased holding temperature. Aqueous samples must not be frozen. Hand-delivered
samples used on the day of collection do not need to be cooled to 0 to 6°C prior to test initiation.
17. Samples collected for the determination of trace level mercury(<100 ng/L)using EPA Method 1631 must be
collected in tightly-capped fluoropolymer or glass bottles and preserved with BrCI or HCI solution within 48
hours of sample collection. The time to preservation may be extended to 28 days if a sample is oxidized in
the sample bottle. A sample collected for dissolved trace level mercury should be filtered in the laboratory
within 24 hours of the time of collection. However, if circumstances preclude overnight shipment, the sample
should be filtered in a designated clean area in the field in accordance with procedures given in Method
1669. If sample integrity will not be maintained by shipment to and filtration in the laboratory,the sample
must be filtered in a designated clean area in the field within the time period necessary to maintain sample
integrity.A sample that has been collected for determination of total or dissolved trace level mercury must
be analyzed within 90 days of sample collection.
18. Aqueous samples must be preserved at s6°C, and should not be frozen unless data demonstrating that
sample freezing does not adversely impact sample integrity is maintained on file and accepted as valid by
the regulatory authority.Also,for purposes of NPDES monitoring, the specification of"s°C" is used in place
of the"4°C"and "<4 °C"sample temperature requirements listed in some methods. It is not necessary to
measure the sample temperature to three significant figures(1/1 00th of 1 degree); rather, three significant
figures are specified so that rounding down to 6°C may not be used to meet the s6 °C requirement.The
preservation temperature does not apply to samples that are analyzed immediately(less than 15 minutes).
19. An aqueous sample may be collected and shipped without acid preservation. However, acid must be added
at least 24 hours before analysis to dissolve any metals that adsorb to the container walls. If the sample
must be analyzed within 24 hours of collection, add the acid immediately(see footnote 2). Soil and sediment
samples do not need to be preserved with acid.The allowances in this footnote supersede the preservation
and holding time requirements in the approved metals methods.
20. To achieve the 28-day holding time, use the ammonium sulfate buffer solution specified in EPA Method
218.6. The allowance in this footnote supersedes preservation and holding time requirements in the
approved hexavalent chromium methods, unless this supersession would compromise the measurement, in
which case requirements in the method must be followed.
21. Holding time is calculated from time of sample collection to elution for samples shipped to the laboratory in
bulk and calculated from the time of sample filtration to elution for samples filtered in the field.
22. Sample analysis should begin as soon as possible after receipt; sample incubation must be started no later
than 8 hours from time of collection.
23. For fecal coliform samples for sewage sludge(biosolids)only, the holding time is extended to 24 hours for
the following sample types using either EPA Method 1680(LTB-EC)or 1681 (A-1): Class A composted,
Class B aerobically digested, and Class B anaerobically digested.
24. The immediate filtration requirement in orthophosphate measurement is to assess the dissolved or bio-
available form of orthophosphorus (i.e., that which passes through a 0.45-micron filter), hence the
requirement to filter the sample immediately upon collection (i.e., within 15 minutes of collection). [38 FR
28758, Oct. 16, 1973].
Appendix B-5

Appendix C
Description of Engineered Drainage Systems for Earthen Dams
At the Allen Steam Ash Basin
Appendix G1

Description of Engineered Drainage Systems for Earthen Dams at the Allen Active Ash Basin
All earth dams are subject to seepage through the embankment,foundation, and abutments. Seepage control
is necessary to prevent excessive uplift pressures, instability of the downstream slope, piping through the
embankment and/or foundation, and erosion of material by migration into open joints in the foundation and
abutments. The control of seepage is performed by the use of engineered drains such as blanket drains,trench
drains, and/or toe drains. In certain cases horizontal pipes may be installed into the embankment to collect and
control seepage. It is standard engineering practice to collect and convey seepage away from the dam.
The text below provides a description of the engineered drainage systems for the active ash basin dams.
GASTO-061 Allen Active Ash Basin Dam
The Allen active ash basin dam consists of an embankment oriented approximately east-to-west, referred to as
the north dike, and an embankment oriented approximately north-to-south, along the Catawba River, referred to
as the east dam.
The east dam was not constructed with any internal seepage drains at the foundation. As shown on Duke
drawing A-3550-2, revision 3, section M-M, a drainage system consisting of washed stone encased in filter
fabric was installed on the north slope of this dike with the top at elevation 627 feet(approximate). The drainage
system terminates at a toe drain which is covered by filter fabric and#67 stone.
The north dam embankment was originally constructed in 1973. In 1982 an additional berm was constructed to
elevation 620 feet against the downstream slope of the original 1973 embankment.The drainage system for the
original 1973 embankment consists of a zoned trench drain, a zoned ladder drain with perforated pipe, and a
zoned blanket drain as shown on drawing A-3350-1 A, revision 19, section C-C.This drainage system was
installed where the embankment foundation elevation was between 575.0 feet to 600.0 feet.
The zoned trench drain and zoned ladder drain with perforated pipe extend from the downstream toe of the
1973 embankment towards the center of the dam, covering the downstream 1/3 of the embankment foundation.
The ladder drains consist of trenches or raised drains filled with a minimum of 12-inches of coarse filter material
surrounded by minimum 9-inch thick layer of fine filter material.A 4-inch diameter perforated pipe is located in
the center of the coarse filter material.These trenches(or raised drains)are spaced at 50 foot centers and are
oriented perpendicular to the zoned trench drain,which is located at the upstream end of the ladder drain. The
trench drain consists of a trench excavated below the foundation grade 4-foot 6 inches deep and filled with a
minimum width of 2-feet of coarse filter material. The coarse filter is surrounded by a minimum 10-inch-thick
layer of fine filter material. A blanket drain of 9-inches of fine filter material is continuous across and between the
ladder trenches or drains of the ladder drain system.
The north dam has a zoned blanket drain and a zoned toe drain constructed under the portions of the dike
constructed in 1982. The zoned blanket drain was constructed to be continuous with the downstream end of the
drainage system constructed under the 1973 embankment. The zoned blanket drain consists of a 12-inch thick
layer of coarse filter material surrounded by 9-inch thick layers of fine filter material above and below the coarse
filter.
The zoned toe drain was constructed where the foundation elevation was from 600 feet to 615 feet(Duke
drawing A-3550-1A Revision 19, Section B-B). The zoned drainage blanket terminates into the zoned toe drain
and consists of unclassified rip-rap, surrounded by filter fabric, placed underneath the extension of the drainage
blanket. The final cover for the zoned toe drain is 15-inches of type C rip-rap.
Appendix C-2

NPDES001
NPDES11
STATION
ABIR po"IT ALLEN RD
N
INACTIVE
•
ASH BASIN
Ak
DUKE ENERGY PROPER FY ASH STORAGE
INACTIVE RETIRED ASH BASIN
ASH BASINA ASH STORAGE ASH LANDFILL
PERMIT
.3612
RIVER RUN
AB-14D J11, AB-9S
_ 9.
NORTH
DIKELAKE WYLIE
Aw
likotaG
LEGEND:
AB-4D
DUKE ENERGY PROPERTY BOUNDARY
ACTIVE ASH BASIN S-6 ASH BASIN WASTE BOUNDARY
Lu ASH STORAGE AREA BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
AB-10S
COINCIDENT WITH DUKE PROPERTY BOUNDARY
1• — STREAM
TOWERNPDES002
TOPOGRAPHIC CONTOUR(4-Fr INTERVAL)
ASH BASIN COMPLIANCE GROUNDWATER
MONITORING WELL
SEEP SAMPLE LOCATION
- NPDES OUTFALL LOCATION
•
AB
SCALE (FEET) DATE
NOTES: 4L, 40U, Boo• IDENTIFIED SEEPS AND WATER QUALITY
1.PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE. SAMPLE LOCATION MAP
2.WASTE BOUNDARY IS APPROXIMATE. -800' OCTOBER 2014
3.AS-BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP. DUKE ENERGY CAROLINAS, LLC
4.TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM(GIS)WEB SITE(DATED 2007). ALLEN STEAM STATION ASH BASIN FIGURE
S.AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 17,2014.
6.THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINrnON FOUND IN 15A NCACO2L.0107(a). GASTON COUNTY, NORTH CAROLINA 1
7.SEEP SAMPLING LOCATIONS ARE APPROXIMATE.
S.NPDES OUTFALL LOCATIONS PROVIDED BY DUKE ENERGY. NPDES PERMIT#NCO004979
9.SEE REPORT"ALLEN STEAM STATION ASH BASIN SURFACE WATER AND SEEP MONITORING-OCTOBER 2014,APPENDIX C'FOR DESCRIPTION OF DAM DRAINAGE SYSTEM.

Attachment 1
Allen Steam Station
NC0004979
Toe drain information

Allen Steam Station
Ash Basin Surface Water and Seep Monitoring
August and September 2014
Introduction
Flow and water quality measurements were collected from nine seep sampling locations(S-1 through S-
9)and two surface water locations near the ash basin (Lake Wylie-Upstream and Lake Wylie-
Downstream)associated with Duke Energy's Allen Steam Station, located in Gaston County, North
Carolina.The purpose of the sampling, which was conducted in late August and early September 2014,
was to measure seepage flows and provide sufficient depth to allow collection of water quality samples for
laboratory analysis. Samples were collected via a combination of methods as described below. See
Figures 1 and 2 for maps of the approximate sampling locations. Descriptions of the seep sampling
locations are provided in Table 1.
A description of the engineering drainage systems for earthen dams at the Cliffside Steam Station Ash
Basin is located in Appendix C.
Seep Flow Measurement Method and Results
A V-notch weir apparatus was utilized at locations S-1, S-2, S-3, and S-4 to impound the seepage in a
channel,which concentrated discharge to a central location that allowed for flow measurements to be
obtained.The weirs were constructed from '/.-inch-thick Plexiglas board material. Each device was
inspected after installation and prior to sampling to confirm sufficient flow and depth for sampling, and to
verify that only minimal leakage, if any, was present. Sufficient time was allowed for the impounded
seepage flows to reach equilibrium discharge flow before flow measurement and sampling.
Flow measurements at seep sampling locations S-5, S-6, and S-7 were collected by installing a 2-inch-
diameter PVC pipe into the ground surface where the seep emerged. Seepage in these locations was
diffuse,with no defined channel. Each PVC pipe was inserted in the location to direct flow through the
pipe. Flow from the pipe was observed until the discharge appeared to be clear of visible fines prior to
sampling for water quality analysis.
Flow measurements at locations S-8 and S-9 were collected from two outfalls consisting of 12-inch-
diameter corrugated metal pipes (CMP). Based on a conversation with Duke Energy personnel familiar
with the site, the source of water discharging from these pipes is unknown. These outfalls exhibited flow
during a dry-weather visual assessment consisting of least 72 hours prior to a rainfall event.The source
of persistent flow from these outfalls is assumed to be groundwater and not stormwater.
The seepage flows at locations S-1 through S-9 were measured using the timed-volumetric method.A
volume of water was collected from the discharge of the weir directly into an appropriately sized container.
Volumes(in mL)were measured in the field utilizing a graduated container.The amount of time(in
seconds)needed to collect the volume of water was recorded and flows(in MGD)were calculated for the
timed-volume. The calculated flows(in MGD)at each seep location are presented in Appendix A.
Seep Water Quality Sample Collection Method and Results
Water quality samples were collected at locations S-1 through S-9.To minimize potential effects of
stormwater runoff, seep samples were collected during a period with minimal preceding rainfall. Samples
were collected from the discharge flow at the flow measurement devices described above or directly
1

from the seep into sample bottles while minimizing disturbance and entrainment of soil/sediment.
Analytical parameters for analysis were:TSS,TDS, Oil &Grease, Cl, SO4, F, COD, Al, As, B, Ba, Ca, Cd,
Cu, Cr, Fe, Mn, Mo, Mg, Ni, Pb, Sb, Se, TI, Zn, Hardness, and Hg. Storage and preservation techniques
of the samples, after collection and prior to analyses, were followed according to Appendix B.Analyses
were conducted by Duke Energy's Huntersville analytical laboratory(NC Wastewater Certification#248)
and Pace Analytical Laboratories(NC Wastewater Certification#12). Laboratory analytical methods used
for each parameter are provided in Table 2 and analytical results are presented in Appendix A.
Seep In-situ Measurement Method and Results
In-situ field parameters(temperature, pH, and specific conductance)were measured at locations S-1
through S-9 utilizing calibrated field meters either at the discharge of the seep directly, at the discharge of
the flow measurement devices, or in the water pool created behind the device, if sufficient water depth did
not exist at the device discharge.The analytical results are presented in Appendix A.
Lake Wylie Water Quality and In-situ Sample Collection Method and Results
Water quality samples and in-situ measurements from were collected at a location upstream (Lake Wylie-
Upstream) and downstream (Lake Wylie-Downstream)of the ash basin(Figure 2).The grab samples
were collected from the surface(0.3 m)directly into appropriate sample bottles. Preservation and
analyses methods for the lake samples are provided in Table 2 and Appendix B.The analytical results are
presented in Appendix A.
Recommendations
The low volume of flow at each seep location, coupled with the relatively low constituent concentrations in
the samples, suggests that there is little potential for Allen Steam Station to influence water quality in Lake
Wylie. If reasonable potential analyses demonstrate that there is no potential to exceed water quality
standards, then Duke Energy proposes to re-evaluate the seep locations listed in this document annually
over the next 5-year permit cycle. These annual evaluations would be documented and would verify the
condition of the existing seeps and determine the presence of new seeps.
The North Carolina Department of Environment and Natural Resources—Division of Water Resources
(DWR)will be promptly notified if any new seeps are identified or any significant changes are observed
for the existing seeps. If any existing or newly identified seeps are determined to reach Lake Wylie, and
demonstrate reasonable potential to exceed a water quality standard, Duke Energy will do one of the
following: 1)stop the seep, 2)capture and route the seep so that it is discharged through a National
Pollutant Discharge Elimination System (NPDES) permitted outfall, or 3)address the seep using Best
Management Plans approved by DWR.
Most of the analytical results upstream and downstream of the ash basin discharge in Lake Wylie with the
exception of copper and zinc are at, or near, the method detection limits and below limits for water quality
standards. Measured values at these two locations are consistent with historical data from previous
monitoring efforts in Lake Wylie. Duke Energy proposes that the semi-annual in-stream monitoring
frequency be maintained.
2

Table 1 —Allen Steam Station Surface Water/Seep Locations and Descriptions
Seep Location Coordinates' Flow
ID Description
Seep Description
Latitude Longitude
S-1 35010.242' 8100.625' Continuous Located south of Active Ash Basin, north of Nutall Oak Lane.Tributary towards Lake
Wylie.Well-defined stream approximately 3-ft wide.
S-2 35010.426' 8100.344' Continuous Located southeast of Active Ash Basin.Tributary towards Lake Wylie.Well-defined
stream approximately 1 ft wide.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-3 35010.513' 8100.360' Continuous approximately 2-ft wide.Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
Located east of Active Ash Basin.Tributary towards Lake Wylie.Well-defined stream
S-4 35010.513' 8100.360' Continuous approximately 1.5-ft wide.Seep collection point may be representative of toe drainage
system downstream of Ash Basin dike.
S-5 35010.621' 81°0.366' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-6 35010.626' 8100.369' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-7 35010.664' 8100.380' Continuous Located east of Active Ash Basin. Unconfined diffuse flow towards Lake Wylie.
S-8 35010.706' 8100.391' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
S-9 35°11.146' 8100.394' Continuous Located east of Active Ash Basin. Flow through is concentrated through a 12-inch CMP.
Notes:
1. Location coordinates(degrees)for seep sampling locations are approximate, and are in NAD 83 datum.
2. Flow description for each seep sample location is based on observation during site visits performed by HDR Engineering, Inc. (HDR)on August
21, 2014. Flow measurements and analytical samples were collected on September 4 and September 9,2014.
3

Table 2—Laboratory Analytical Methods
Parameter Method Reporting Units Laboratory
Limit
Chemical Oxygen HACH 8000 20 mg/L Duke Energy
Demand COD
Chloride(CI) EPA 300.0 1 mg/L Duke Energy
Fluoride(FI) EPA 300.0 1 mg/L Duke Energy
Sulfate(SO4) EPA 300.0 1 mg/L Duke Energy
Oil and Grease EPA 1664B 5 ug/L Pace Analtyical
Mercury(Hg) EPA 245.1 0.05 ug/L Duke Energy
Aluminum (AI) EPA 200.7 0.005 mg/L Duke Energy
Barium (Ba) EPA 200.7 0.005 mg/L Duke Energy
Boron (B) EPA 200.7 0.05 mg/L Duke Energy
Calcium(Ca) EPA 200.7 0.01 mg/L Duke Energy
Hardness EPA 200.7 0.19 mg/L(CaCO3) Duke Energy
Iron (Fe) EPA 200.7 0.01 mg/L Duke Energy
Magnesium (Mg) EPA 200.7 0.005 mg/L Duke Energy
Manganese(Mn) EPA 200.7 0.005 mg/L Duke Energy
Zinc(Zn) EPA 200.7 0.005 mg/L Duke Energy
Antimony(Sb) EPA 200.8 1 ug/L Duke Energy
Arsenic(As) EPA 200.8 1 ug/L Duke Energy
Cadmium (Cd) EPA 200.8 1 ug/L Duke Energy
Chromium (Cr) EPA 200.8 1 ug/L Duke Energy
Copper(Cu) EPA 200.8 1 mg/L Duke Energy
Lead (Pb) EPA 200.8 1 ug/L Duke Energy
Molybdenum (Mo) EPA 200.8 1 ug/L Duke Energy
Nickel(Ni) EPA 200.8 1 ug/L Duke Energy
Selenium (Se) EPA 200.8 1 ug/L Duke Energy
Thallium(TI) Low Level EPA 200.8 0.2 ug/L Duke Energy
TDS SM2540C 25 mg/L Duke Energy
TSS SM2540D 5 mg/L Duke Energy
4

Appendix A
Seep Flows and Analytical Results
Appendix A-1

Allen Steam Station
Surface Water/Seep Monitoring Analytical Results-September 2014
Parameter Units Y Y
Seep Monitoring Location Lake Wylie- Lake W lie-
S-1 S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 Upstream2,3 Downstream2.3
Oil&Grease mg/1 <5 <5 <5.0 <5 <5 <5.0 <5 <5 <5 N/A N/A
COD-Chemical Oxygen Demand mg/I <20 <20 20 <20 <20 <20 <20 <20 <20 N/A N/A
Cl-Chloride(00940) mg/I 4.3 49 32 41 59 62 7.8 7.5 9.1 N/A N/A
FI-Fluoride mg/l 0.11 0.1 0.13 <0.1 <0.1 0.11 <0.1 0.17 <0.5 N/A N/A
SO4-Sulfate(00945) mg/l 1.4 10 26 21 42 55 74 87 180 N/A N/A
Hg-Mercury(71900) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
AI-Aluminum (01105) mg/I 0.996 0.467 0.039 0.022 <0.005 0.21 0.083 0.01 0.254 WA N/A
Ba- Barium (01007) mg/I 0.044 0.114 0.044 0.047 0.208 0.307 0.057 0.060 0.029 N/A N/A
B-Boron(01022) mg/l <0.05 0.871 0.555 0.713 0.927 1.01 0.934 0.606 1.49 N/A N/A
Ca-Calcium mg/I 7.34 7.25 61.7 73.4 20.7 19.8 17.8 97.6 138 N/A N/A
Hardness mg/1(CaCO3) 31.9 74.4 203 251 111 112 76 292 413 N/A N/A
Fe-Iron (01045) mg/I 1.86 1.25 0.136 0.215 <0.01 0.015 0.113 0.011 0.942 N/A N/A
Mg-Magnesium mg/l 3.29 13.7 12 16.4 14.4 15.2 7.69 11.7 16.5 N/A WA
Mn-Manganese(01055) mg/I 0.356 0.305 0.131 0.310 1.45 2.25 0.395 <0.005 0.998 N/A NIA
Zn-Zinc(01092) mg/l <0.005 <0.005 <0.005 <0.005 0.011 <0.005 <0.005 <0.005 0.283 3.08 <2
Sb-Antimony(01097) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 N/A N/A
As-Arsenic(01002) twi <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cd-Cadmium (01027) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cr-Chromium(01034) Ng/l 1.42 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Cu-Copper(01042) Ng/I <1 <1 <1 <1 <1 1.14 <1 <1 1.31 2.80 2.60
Pb-Lead (01051) Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
Mo-Molybdenum Ng/I <1 <1 <1 <1 <1 <1 <1 <1 <1 N/A N/A
Ni-Nickel(01067) Ng/I <1 1.58 <1 <1 8.23 2.29 <1 <1 2.78 N/A N/A
Se-Selenium(01147) pg/I <1 <1 <1 <1 <1 <1 <1 <1 <1 <1 <1
TI-Thallium(01059) Ng/I <0.2 <0.2 <0.2 <0.2 <0.2 0.273 <0.2 <0.2 <0.2 WA WA
TDS-Total Dissolved Solids(70300) mg/I 110 170 300 320 230 220 180 360 500 54 53
TSS-Total Suspended Solids mg/I 38 8 <5 <5 <5 <5 <5 <5 <5 N/A N/A
pH s.u. 6.63 6.33 6.95 6.92 5.56 4.67 5.64 8.11 7.52 N/A N/A
Temperature °C 23.8 20.9 21.5 21.6 17.6 17.6 20.4 23.6 19 N/A WA
Specific conductance NS/cm 107 229 447 524 326 341 222 555 717 N/A N/A
Flow MGD 0.0004 0.0025 0.0083 0.0008 0.0023 0.0002 0.0002 0.0002 0.0002 WA N/A
Notes:
1. Flow measurements and analytical samples were collected on September 4 and 9,2014.
2. N/A indicates not applicable.
3. Lake Wylie samples were collected on August 27, 2014.
Appendix A-2

Appendix B
Sample Preservation and Hold Times
Appendix B-1

Parameter Name Container' Preservation 2.3 Maximum
Holding Time4
Table IB—Inorganic Tests
1. Acidity P, FP, G Cool, 56 °C'' 14 days
2.Alkalinity P, FP, G Cool,56°C'6 14 days
4.Ammonia P, FP, G Cool, 56°C16, H2SO4 to pH<2 28 days
9. Biochemical oxygen demand P, FP, G Cool, 56°C16 48 hours
10. Boron P, FP, or HNO3 to pH <2 6 months
Quartz
11. Bromide P, FP, G None required 28 days
14. Biochemical oxygen demand, P, FP G Cool, s6 °C'3 48 hours
carbonaceous
15. Chemical oxygen demand P, FP, G Cool, 56°C18, H2SO4 to pH <2 28 days
16.Chloride P, FP, G None required 28 days
17.Chlorine,total residual P, G None required Analyze within 15
minutes
21. Color P, FP, G Cool, 56°C76 48 hours
23-24. Cyanide,total or available P, FP, G Cool, s6°C16, NaOH to pH 14 days
(or CRTC)and free >105,6 reducing agent if oxidizer
present
25. Fluoride P None required 28 days
27. Hardness P, FP, G HNO3 or H2SO4to pH<2 6 months
28. Hydrogen ion (pH) P, FP, G None required Analyze within 15
minutes
31,43. Kjeldahl and organic N P, FP, G Cool, s6 00, H2SO4 to pH <2 28 days
Table IB—Metals
18. Chromium VI P, FP, G Cool, 56°C15, pH=9.3-9.720 28 days
35. Mercury(CVAA) P, FP, G HNO3 to pH<2 28 days
35. Mercury(CVAFS) FP, G; and FP- 5 mUL 12N HCI or 5 mUL 90 daysl7
lined cap17 BrCl17
3, 5-8, 12, 13, 19, 20,22,26,29,30, P, FP, G HNO3 to pH<2, or at least 24 6 months
32-34, 36, 37, 45,47, 51, 52, 58-60, hours prior to analysis19
62, 63,70-72, 74, 75. Metals,
except boron, chromium VI, and
mercury
38. Nitrate P, FP, G Cool, 56 00 48 hours
39. Nitrate-nitrite P, FP, G Cool, 56°C16, H2SO4 to pH <2 28 days
40. Nitrite P, FP, G Cool, 56°C16 48 hours
41. Oil and grease G Cool to 56 °C75, HCI or H2SO4 to 28 days
PH<2
Appendix B-2

Parameter Name Container' Preservation 2'3 Maximum
Holding Time4
42. Organic Carbon P, FP, G Cool to s6°C'', HCI, H2SO4, or 28 days
H3PO4 to pH<2
44.Orthophosphate P, FP, G Cool,to 56 °C111'!4 Filter within 15
minutes; analyze
within 48 hours
46.Oxygen, Dissolved Probe G, Bottle and None required Analyze within 15
top minutes
47.Winkler G, Bottle and Fix on site and store in dark 8 hours
top
48. Phenols G Cool, s6°C'", H2SO4 to pH <2 28 days
49. Phosphorous(elemental) G Cool, 56 °C'' 48 hours
50. Phosphorous,total P, FP, G Cool, s6 °C'', H2SO4 to pH<2 28 days
53. Residue,total P, FP, G Cool, 56°C'' 7 days
54. Residue, Filterable P, FP, G Cool, 56°C'' 7 days
55. Residue, Nonfilterable(TSS) P, FP, G Cool, s6°C" 7 days
56. Residue, Settleable P, FP, G Cool, s6°C13 48 hours
57. Residue,Volatile P, FP, G Cool, 56°C13 7 days
61. Silica P or Quartz Cool, 56°C" 28 days
64. Specific conductance P, FP, G Cool, s6°C"' 28 days
65. Sulfate P, FP, G Cool, s6°C'' 28 days
66. Sulfide P, FP, G Cool, s6 00, add zinc acetate 7 days
plus sodium hydroxide to pH >9
67. Sulfite P, FP, G None required Analyze within 15
minutes
68. Surfactants P, FP, G Cool, 56°C"3 48 hours
69.Temperature P, FP, G None required Analyze
73.Turbidity P, FP, G Cool, 56 °C'' 48 hours
Notes:
1. "P"is for polyethylene; "FP" is fluoropolymer(polytetrafluoroethylene(PTFE);Teflon®), or other
fluoropolymer, unless stated otherwise in this table; and "G" is glass.
2. Except where noted in this table and the method for the parameter, preserve each grab sample within 15
minutes of collection. For a composite sample collected with an automated sample(e.g., using a 24-hour
composite sample; see 40 CFR 122.21(g)(7)(i)or 40 CFR Part 403,Appendix E), refrigerate the sample at
56°C during collection unless specified otherwise in this table or in the method(s). For a composite sample
to be split into separate aliquots for preservation and/or analysis, maintain the sample at 56°C, unless
specified otherwise in this table or in the method(s), until collection, splitting, and preservation is completed.
Add the preservative to the sample container prior to sample collection when the preservative will not
compromise the integrity of a grab sample, a composite sample, or aliquot split from a composite sample
within 15 minutes of collection. If a composite measurement is required but a composite sample would
compromise sample integrity, individual grab samples must be collected at prescribed time intervals(e.g., 4
samples over the course of a day, at 6-hour intervals). Grab samples must be analyzed separately and the
concentrations averaged. Alternatively, grab samples may be collected in the field and composited in the
laboratory if the compositing procedure produces results equivalent to results produced by arithmetic
averaging of results of analysis of individual grab samples. For examples of laboratory compositing
Appendix B-3

procedures, see EPA Method 1664 Rev.A(oil and grease)and the procedures at 40 CFR 141.34(f)(14)(iv)
and (v)(volatile organics).
3. When any sample is to be shipped by common carrier or sent via the U.S. Postal Service, it must comply
with the Department of Transportation Hazardous Materials Regulations(49 CFR part 172). The person
offering such material for transportation is responsible for ensuring such compliance. For the preservation
requirement of this table, the Office of Hazardous Materials, Materials Transportation Bureau, Department of
Transportation has determined that the Hazardous Materials Regulations do not apply to the following
materials: Hydrochloric acid (HCI) in water solutions at concentrations of 0.04% by weight or less (pH about
1.96 or greater; Nitric acid (HNO3)in water solutions at concentrations of 0.15% by weight or less(pH about
1.62 or greater); Sulfuric acid (H2SO4)in water solutions at concentrations of 0.35% by weight or less (pH
about 1.15 or greater); and Sodium hydroxide(NaOH)in water solutions at concentrations of 0.080% by
weight or less(pH about 12.30 or less).
4. Samples should be analyzed as soon as possible after collection. The times listed are the maximum times
that samples may be held before the start of analysis and still be considered valid. Samples may be held for
longer periods only if the permittee or monitoring laboratory has data on file to show that,for the specific
types of samples under study, the analytes are stable for the longer time, and has received a variance from
the Regional Administrator under Sec. 136.3(e). For a grab sample, the holding time begins at the time of
collection. For a composite sample collected with an automated sampler(e.g., using a 24-hour composite
sampler; see 40 CFR 122.21(g)(7)(i)or 40 CFR part 403, Appendix E), the holding time begins at the time of
the end of collection of the composite sample. For a set of grab samples composited in the field or
laboratory, the holding time begins at the time of collection of the last grab sample in the set. Some samples
may not be stable for the maximum time period given in the table. A permittee or monitoring laboratory is
obligated to hold the sample for a shorter time if it knows that a shorter time is necessary to maintain sample
stability. See 136.3(e)for details. The date and time of collection of an individual grab sample is the date
and time at which the sample is collected. For a set of grab samples to be composited, and that are all
collected on the same calendar date, the date of collection is the date on which the samples are collected.
For a set of grab samples to be composited, and that are collected across two calendar dates, the date of
collection is the dates of the two days; e.g., November 14-15. For a composite sample collected
automatically on a given date, the date of collection is the date on which the sample is collected. For a
composite sample collected automatically, and that is collected across two calendar dates, the date of
collection is the dates of the two days; e.g., November 14-15. For static-renewal toxicity tests, each grab or
composite sample may also be used to prepare test solutions for renewal at 24 h, 48 h, and/or 72 h after
first use, if stored at 0-6°C, with minimum head space.
5. ASTM D7365-09a specifies treatment options for samples containing oxidants (e.g., chlorine). Also, Section
9060A of Standard Methods for the Examination of Water and Wastewater(20th and 21 st editions)
addresses dechlorination procedures.
6. Sampling, preservation and mitigating interferences in water samples for analysis of cyanide are described
in ASTM D7365-09a.There may be interferences that are not mitigated by the analytical test methods or
D7365-09a.Any technique for removal or suppression of interference may be employed, provided the
laboratory demonstrates that it more accurately measures cyanide through quality control measures
described in the analytical test method.Any removal or suppression technique not described in D7365-09a
or the analytical test method must be documented along with supporting data.
7. For dissolved metals, filter grab samples within 15 minutes of collection and before adding preservatives.
For a composite sample collected with an automated sampler(e.g., using a 24-hour composite sampler; see
40 CFR 122.21(g)(7)(i)or 40 CFR Part 403, Appendix E),filter the sample within 15 minutes after
completion of collection and before adding preservatives. If it is known or suspected that dissolved sample
integrity will be compromised during collection of a composite sample collected automatically over time
(e.g., by interchange of a metal between dissolved and suspended forms), collect and filter grab samples to
be composited(footnote 2) in place of a composite sample collected automatically.
8. Guidance applies to samples to be analyzed by GC, LC, or GC/MS for specific compounds.
9. If the sample is not adjusted to pH 2, then the sample must be analyzed within seven days of sampling.
10. The pH adjustment is not required if acrolein will not be measured. Samples for acrolein receiving no pH
adjustment must be analyzed within 3 days of sampling.
11. When the extractable analytes of concern fall within a single chemical category, the specified preservative
and maximum holding times should be observed for optimum safeguard of sample integrity(i.e., use all
necessary preservatives and hold for the shortest time listed).When the analytes of concern fall within two
or more chemical categories, the sample may be preserved by cooling to s6 °C, reducing residual chlorine
with 0.008%sodium thiosulfate, storing in the dark, and adjusting the pH to 6-9; samples preserved in this
manner may be held for seven days before extraction and for forty days after extraction. Exceptions to this
optional preservation and holding time procedure are noted in footnote 5(regarding the requirement for
Appendix B-4

thiosulfate reduction), and footnotes 12, 13(regarding the analysis of benzidine).
12. If 1,2-diphenylhydrazine is likely to be present, adjust the pH of the sample to 4.0 t0.2 to prevent
rearrangement to benzidine.
13. Extracts may be stored up to 30 days at<0 °C.
14. For the analysis of diphenylnitrosamine, add 0.008% Na2S2O3 and adjust pH to 7-10 with NaOH within 24
hours of sampling.
15. The pH adjustment may be performed upon receipt at the laboratory and may be omitted if the samples are
extracted within 72 hours of collection. For the analysis of aldrin, add 0.008% Na2S203.
16. Place sufficient ice with the samples in the shipping container to ensure that ice is still present when the
samples arrive at the laboratory. However, even if ice is present when the samples arrive, immediately
measure the temperature of the samples and confirm that the preservation temperature maximum has not
been exceeded. In the isolated cases where it can be documented that this holding temperature cannot be
met, the permittee can be given the option of on-site testing or can request a variance.The request for a
variance should include supportive data which show that the toxicity of the effluent samples is not reduced
because of the increased holding temperature. Aqueous samples must not be frozen. Hand-delivered
samples used on the day of collection do not need to be cooled to 0 to 6 °C prior to test initiation.
17. Samples collected for the determination of trace level mercury(<100 ng/L)using EPA Method 1631 must be
collected in tightly-capped fluoropolymer or glass bottles and preserved with BrCI or HCI solution within 48
hours of sample collection. The time to preservation may be extended to 28 days if a sample is oxidized in
the sample bottle.A sample collected for dissolved trace level mercury should be filtered in the laboratory
within 24 hours of the time of collection. However, if circumstances preclude overnight shipment, the sample
should be filtered in a designated clean area in the field in accordance with procedures given in Method
1669. If sample integrity will not be maintained by shipment to and filtration in the laboratory, the sample
must be filtered in a designated clean area in the field within the time period necessary to maintain sample
integrity. A sample that has been collected for determination of total or dissolved trace level mercury must
be analyzed within 90 days of sample collection.
18. Aqueous samples must be preserved at s6°C, and should not be frozen unless data demonstrating that
sample freezing does not adversely impact sample integrity is maintained on file and accepted as valid by
the regulatory authority. Also,for purposes of NPDES monitoring, the specification of"s°C" is used in place
of the"4 °C"and "<4 °C"sample temperature requirements listed in some methods. It is not necessary to
measure the sample temperature to three significant figures(1/1 00th of 1 degree); rather, three significant
figures are specified so that rounding down to 6°C may not be used to meet the 56°C requirement.The
preservation temperature does not apply to samples that are analyzed immediately(less than 15 minutes).
19. An aqueous sample may be collected and shipped without acid preservation. However, acid must be added
at least 24 hours before analysis to dissolve any metals that adsorb to the container walls. If the sample
must be analyzed within 24 hours of collection, add the acid immediately(see footnote 2). Soil and sediment
samples do not need to be preserved with acid.The allowances in this footnote supersede the preservation
and holding time requirements in the approved metals methods.
20. To achieve the 28-day holding time, use the ammonium sulfate buffer solution specified in EPA Method
218.6.The allowance in this footnote supersedes preservation and holding time requirements in the
approved hexavalent chromium methods, unless this supersession would compromise the measurement, in
which case requirements in the method must be followed.
21. Holding time is calculated from time of sample collection to elution for samples shipped to the laboratory in
bulk and calculated from the time of sample filtration to elution for samples filtered in the field.
22. Sample analysis should begin as soon as possible after receipt; sample incubation must be started no later
than 8 hours from time of collection.
23. For fecal coliform samples for sewage sludge(biosolids)only, the holding time is extended to 24 hours for
the following sample types using either EPA Method 1680(LTB-EC)or 1681 (A-1): Class A composted,
Class B aerobically digested, and Class B anaerobically digested.
24. The immediate filtration requirement in orthophosphate measurement is to assess the dissolved or bio-
available form of orthophosphorus(i.e., that which passes through a 0.45-micron filter), hence the
requirement to filter the sample immediately upon collection(i.e., within 15 minutes of collection). [38 FR
28758, Oct. 16, 1973].
Appendix B-5

Appendix C
Description of Engineered Drainage Systems for Earthen Dams
At the Allen Steam Ash Basin
Appendix C-1

Description of Engineered Drainage Systems for Earthen Dams at the Allen Active Ash Basin
All earth dams are subject to seepage through the embankment,foundation, and abutments. Seepage control
is necessary to prevent excessive uplift pressures, instability of the downstream slope, piping through the
embankment and/or foundation, and erosion of material by migration into open joints in the foundation and
abutments. The control of seepage is performed by the use of engineered drains such as blanket drains, trench
drains, and/or toe drains. In certain cases horizontal pipes may be installed into the embankment to collect and
control seepage. It is standard engineering practice to collect and convey seepage away from the dam.
The text below provides a description of the engineered drainage systems for the active ash basin dams.
GASTO-061 Allen Active Ash Basin Dam
The Allen active ash basin dam consists of an embankment oriented approximately east-to-west, referred to as
the north dike, and an embankment oriented approximately north-to-south, along the Catawba River, referred to
as the east dam.
The east dam was not constructed with any internal seepage drains at the foundation.As shown on Duke
drawing A-3550-2, revision 3, section M-M, a drainage system consisting of washed stone encased in filter
fabric was installed on the north slope of this dike with the top at elevation 627 feet(approximate). The drainage
system terminates at a toe drain which is covered by filter fabric and#67 stone.
The north dam embankment was originally constructed in 1973. In 1982 an additional berm was constructed to
elevation 620 feet against the downstream slope of the original 1973 embankment.The drainage system for the
original 1973 embankment consists of a zoned trench drain, a zoned ladder drain with perforated pipe, and a
zoned blanket drain as shown on drawing A-3350-1 A, revision 19, section C-C.This drainage system was
installed where the embankment foundation elevation was between 575.0 feet to 600.0 feet.
The zoned trench drain and zoned ladder drain with perforated pipe extend from the downstream toe of the
1973 embankment towards the center of the dam, covering the downstream 1/3 of the embankment foundation.
The ladder drains consist of trenches or raised drains filled with a minimum of 12-inches of coarse filter material
surrounded by minimum 9-inch thick layer of fine filter material. A 4-inch diameter perforated pipe is located in
the center of the coarse filter material.These trenches(or raised drains)are spaced at 50 foot centers and are
oriented perpendicular to the zoned trench drain, which is located at the upstream end of the ladder drain. The
trench drain consists of a trench excavated below the foundation grade 4-foot 6 inches deep and filled with a
minimum width of 2-feet of coarse filter material. The coarse filter is surrounded by a minimum 10-inch-thick
layer of fine filter material. A blanket drain of 9-inches of fine filter material is continuous across and between the
ladder trenches or drains of the ladder drain system.
The north dam has a zoned blanket drain and a zoned toe drain constructed under the portions of the dike
constructed in 1982. The zoned blanket drain was constructed to be continuous with the downstream end of the
drainage system constructed under the 1973 embankment. The zoned blanket drain consists of a 12-inch thick
layer of coarse filter material surrounded by 9-inch thick layers of fine filter material above and below the coarse
filter.
The zoned toe drain was constructed where the foundation elevation was from 600 feet to 615 feet(Duke
drawing A-3550-1A Revision 19, Section B-B). The zoned drainage blanket terminates into the zoned toe drain
and consists of unclassified rip-rap, surrounded by filter fabric, placed underneath the extension of the drainage
blanket. The final cover for the zoned toe drain is 15-inches of type C rip-rap.
Appendix C-2

NPDES00l
STATION
I
AjtN
RETIREDINACTIVEASH BASIN-\
DUKE ENERGY PROPERTY ASHSTORAGE _j 4
INACTIVE ASH BASIN
ASH ; . 1
.• ,
NO.3612
RIVER RUN
IF .,
NORTH
s
DIKE
LAKE WYLIE
(CATAWBA RIVER)
1
LEGEND:
AB-4 uj
AB-4D S-7
DUKE ENERGY PROPERTY BOUNDARY
ACTIVE ASH BASIN S-6 ASH BASIN WASTE BOUNDARY
Lu ASH STORAGE AREA BOUNDARY
ASH BASIN COMPLIANCE BOUNDARY
_ ASH BASIN COMPLIANCE BOUNDARY
COINCIDENT WITH DUKE PROPERTY BOUNDARY
1
1• - . .. — STREAM
OOD; 1 011 DISCHARGE TOWER - ------- TOPOGRAPHIC CONTOUR(4FT INTERVAL)
•. 11
J'� ASH BASIN COMPLIANCE GROUNDWATER
�J" MONITORING WELL
• SEEP SAMPLE LOCATION
- NPDES OUTFALL LOCATION
•
AB-11D A•
ow
• vt
'
NOTES: adoSCALE (FEET)4na Boo, IDENTIFIED SEEPS AND WATER QUALITY DATE
' `
1.PARCEL DATA FOR THE SITE WAS OBTAINED FROM DUKE ENERGY REAL ESTATE AND IS APPROXIMATE. SAMPLE LOCATION MAP OCTOBER 2Q14
2.WASTE BOUNDARY IS APPROXIMATE. !'=800'
3.AS-BUILT MONITORING WELL LOCATIONS PROVIDED BY DUKE ENERGY AND WSP. DUKE ENERGY CAROLINAS, LLC
4.TOPOGRAPHY DATA FOR THE SITE WAS OBTAINED FROM NC DOT GEOGRAPHIC INFORMATION SYSTEM(GIS)WEB SITE(DATED 2007). ALLEN STEAM STATION ASH BASIN FIGURE
S.AERIAL PHOTOGRAPHY WAS OBTAINED FROM WSP DATED APRIL 17,2014. F)l
6.THE COMPLIANCE BOUNDARY IS ESTABLISHED ACCORDING TO THE DEFINITION FOUND IN 1SA NCAC 02L.0107(a). GASTON COUNTY, NORTH CAROLINA 1
7.SEEP SAMPLING LOCATIONS ARE APPROXIMATE.
S.NPDES OUTFALL LOCATIONS PROVIDED BY DUKE ENERGY. NPDES PERMIT#NCO004979
9.SEE REPORT"ALLEN STEAM STATION ASH BASIN SURFACE WATER AND SEEP MONITORING-OCTOBER 2014,APPENDIX C-FOR DESCRIPTION OF DAM DRAINAGE SYSTEM.