NC0004979_316 (b) Alternate Schedule Request_20141015

316 (b)Alternate
Schedule Request

Alternate Schedule Request§316(b)of the Clean Water Act
Allen Steam Station
Final regulations to establish requirements for cooling water intake structures at existing facilities were
published in the Federal Register on August 15, 2014(i.e. regulations implementing§316(b)of the Clean
Water Act)with an effective date of October 14, 2014. Allen Steam Station is subject to the regulations.
The design intake flow of the station is greater than 2 million gallons per day (MGD) and the historical
actual intake flows are greater than 125 MGD; therefore, the following submittals are expected to be
required:
— §122.21(r)(2)Source Water Physical Data
— §122.21(r)(3)Cooling Water Intake Structure Data
— §122.21(r)(4)Source Water Baseline Biological Characterization Data
— §122.21(r)(5)Cooling Water System Data
— §122.21(r)(6)Chosen Method(s)of Compliance with the Impingement Mortality Standard
— §122.21(r)(7) Entrainment Performance Studies
— §122.21(r)(8)Operational Status
— §122.21(r)(9) Entrainment Characterization Study
— §122.21(r)(10)Comprehensive Technical Feasibility and Cost Evaluation Study
— §122.21(r)(11)Benefits Valuation Study
— §122.21(r)(12) Non-water Quality and Other Environmental Impacts Study
As allowed under §125.95(a)(2), Duke Energy would like to request an alternate schedule for the
submittals listed above. Allen Steam Station was not subject to the remanded Phase II Rule due to the
intake velocity; therefore, none of the above submittals were prepared. Duke Energy will need at least
60 months to prepare the necessary submittals.This timeframe includes complying with the peer review
requirement for submittals§122.21(r)(10), §122.21(r)(11), and§122.21(r)(12).
The rule requires the necessary submittals to be included with the permit renewal application for
permits with an effective date after July 14, 2018. Duke Energy, therefore, would like to request the
316(b) submittals, with the exception of §122.21(r)(6) Chosen Method(s) of Compliance with
Impingement Mortality Standard, for Allen Steam Station to be required with the subsequent permit
renewal application after July 14, 2018. Since Allen Steam Station is subject to the entrainment best
technology available (BTA) determination, a compliance schedule to complete §122.21(r)(6) Chosen
Method(s) of Compliance with Impingement Mortality Standard will be requested to be included in the
permit upon issuance of the entrainment BTA determination.

Fish Tissue Monitoring

Allen Steam Station
NPDES Permit No. NC0004979
Monitoring of Arsenic,Selenium and Mercury in Fish Muscle Tissue from Upper
Lake Wylie,NC
Duke Energy
2014

Table of Contents
Page
1.0 Introduction 1
2.0 Study Site Description and Sampling Locations 1
3.0 Target Species 1
4.0 Field Sampling Methods 1
5.0 Laboratory Processing and Arsenic,Selenium and Mercury Analysis 2
6.0 Data Analysis and Reporting 2
7.0 References 2
List of Tables
Page
Table
1 Arsenic,selenium and mercury concentrations in axial muscle of fish from Lake
Wylie during April 2014. 3
List of Figures
Page
Figure
1 Lake Wylie arsenic,selenium and mercury monitoring locations 4

1.0 Introduction
Duke Energy owns and operates the Allen Steam Station located on upper Lake Wylie in Gaston
County, Belmont, NC. The Allen Station's National Pollutant Discharge Elimination System
(NPDES) Permit (No. NC0004977 Section A 16) requires monitoring of trace elements (arsenic,
selenium and mercury) in fish tissues near the discharge once per permit cycle. Fish were collected
according to the submitted study plan(dated December 4, 2013). The resulting data are submitted in
this report.
2.0 Study Site Description and Sampling Locations
Fish were collected from three locations in upper Lake Wylie (Figure 1). These locations were
adjacent to the Allen Station discharge (DI), 6.2 kilometers upstream (UP) and 10.9 kilometers
downstream of the discharge(DN).
3.0 Target Species
The target species of fish were largemouth bass and redear sunfish. As recommended by the US
Environmental Protection Agency (EPA), an attempt was made to limit the smallest fish to 75%
of the largest fish total length by species depending on availability(US EPA 2000).
4.0 Field Sampling Methods
Fish were collected using electrofishing according to our Biology Program Procedures Manual
(Procedure NR-00080, Rev. 1), which is approved by the NC Division of Water Resources under
the Company's NC Biological Laboratory Certification (# 006), located at New Hill, NC. Only
live fish that showed little or no signs of deterioration were retained for analysis. Retained fish
were individually tagged(Floy tags), identified to species,measured for total length(mm), weight
(g),placed on ice until frozen and transferred to a freezer within 24 hours of collection.
Water quality data consisting of temperature, pH, dissolved oxygen, specific conductance and
turbidity were recorded daily at the surface at each sampling location. Other noteworthy
environmental conditions including river flow conditions and weather conditions were noted and
are available upon request.
1

5.0 Laboratory Processing and Arsenic,Selenium and Mercury Analysis
All fish samples were processed in the New Hill trace element laboratory according to procedure
NR-00107 (Rev. 4) Trace Element Monitoring Laboratory Procedure. The processed samples
(lyophilized left axial muscle; right muscle occasionally included when needed) were analyzed
for arsenic, selenium and mercury by x-ray spectrophotometry. Quality control was achieved by
analytical standards, replicates and certified reference materials. The remaining fish carcasses
were archived and will be kept at least two years in the event that re-analysis is needed.
6.0 Data Analysis and Reporting
Arsenic, selenium and mercury concentrations(converted to µg/g fresh weight) in the fish muscle
tissue collected during 2014 are shown in Table 1. In addition to the length and weight of each
fish, the dry-to-fresh weight ratios are presented to convert the arsenic, selenium and mercury
concentrations fresh weight values back to dry weight values as desired. All fish collected during
2014 were below the US EPA Screening Values for Recreational Fishermen of 1.2 µg/g (fresh
weight) for arsenic (US EPA 2000). All fish collected during 2014 were below the NC human
consumption advisory level of 10 µg/g(fresh weight) for selenium. All fish collected during 2014
had mercury concentrations below the NC Health Directors Action Advisory Level of 0.4 µg/g
fresh weight(NCDHHS 2006).
References
NCDHHS. 2006. Health effects of methylmercury and North Carolina's advice on eating fish.
North Carolina Occupational and Environmental Epidemiology Branch,Raleigh,NC.
US EPA. 2000. Guidance for assessing chemical contaminant data for use in fish advisories. Vol. 1.
Fish sampling and analysis. Third edition. EPA 823-B-00-007. United States Environmental
Protection Agency,Office of Water,Washington,DC.
2

Table 1. Arsenic, selenium and mercury concentrations (fresh weight) in axial muscle of
fish from upper Lake Wylie during April 2014.
Length Weight As Se Hg Dry-to-fresh
Fish species Location Month (mm) (g) (pg/g) (pg/g) (pg/g) weight ratio*
Largemouth bass UP April 377 630 0.21 0.37 <0.05 0.193
Largemouth bass UP April 411 878 0.08 0.40 <0.05 0.190
Largemouth bass UP April 408 822 0.14 0.45 <0.06 0.205
Largemouth bass UP April 316 381 0.18 0.47 <0.05 0.195
Largemouth bass UP April 338 550 0.08 0.35 <0.06 0.205
Largemouth bass UP April 422 952 <0.03 0.27 <0.03 0.127
Redear sunfish UP April 235 263 <0.04 0.70 <0.06 0.211
Redear sunfish UP April 224 195 0.04 0.79 <0.05 0.202
Redear sunfish UP April 218 162 0.04 0.52 <0.05 0.192
Redear sunfish UP April 261 283 0.06 0.52 <0.05 0.187
Redear sunfish UP April 214 161 <0.04 0.52 <0.05 0.200
Redear sunfish UP April 206 154 0.06 0.68 <0.05 0/00
Largemouth bass DI April 332 427 0.18 0.36 <0.05 0.198
Largemouth bass DI April 325 450 0.19 0.46 <0.06 0.209
Largemouth bass DI April 371 635 0.23 0.42 <0.06 0.209
Largemouth bass DI April 348 514 0.23 0.41 <0.06 0.206
Largemouth bass DI April 321 354 0.15 0.53 <0.05 0.190
Largemouth bass DI April 374 671 0.14 0.65 <0.05 0.198
Redear sunfish DI April 228 193 0.16 0.81 <0.05 0/03
Redear sunfish DI April 240 233 0.14 0.62 <0.05 0.194
Redear sunfish DI April 209 132 0.06 0.64 <0.06 0.207
Redear sunfish DI April 260 284 0.15 0.65 <0.05 0.191
Redear sunfish DI April 219 162 0.11 0.63 <0.05 0.185
Redear sunfish DI April 223 166 0.04 0.52 <0.05 0.186
Largemouth bass DN April 344 491 0.29 0.35 <0.05 0.196
Largemouth bass DN April 361 558 0.26 0.32 <0.06 0.214
Largemouth bass DN April 365 559 0.21 0.38 <0.06 0.213
Largemouth bass DN April 355 610 0.20 0.36 <0.05 0.197
Largemouth bass DN April 362 580 0.18 0.44 <0.05 0.198
Largemouth bass DN April 349 551 0.24 0.40 <0.05 0.200
Redear sunfish DN April 219 150 0.09 0.44 <0.05 0.185
Redear sunfish DN April 246 253 0.10 0.51 <0.05 0.198
Redear sunfish DN April 215 172 0.04 0.43 <0.05 0.195
Redear sunfish DN April 210 150 <0.04 0.46 <0.05 0.201
Redear sunfish DN April 203 146 0.04 0.49 <0.05 0.197
Redear sunfish DN April 209 155 0.04 0.53 0.05 0.203
*To convert to a dry weight,divide the fresh weight concentrations by the dry-to-fresh weight ratio.
3

ON
Lake

Metals Sampling in the Vicinity
Of Ash Basins

Allen Steam Station In-Stream Monitoring Plan 2011 -
Present
In-stream Monitoring Requirement
A requirement to sample locations in Lake Wylie, semi-annually,upstream and downstream of the Allen
Steam Station(AS) ash basin discharge was implemented in the March 1, 2011 AS National Pollutant
Discharge Elimination System permit under section A.17 of the permit. The following document details
methods and analyses of the monitoring program and provides the monitoring data to meet this
requirement.
In-stream Sampling Locations
Lake Wylie water sampling locations are depicted in Figure 1. The upstream location(250) is
approximately two miles upstream of the AS ash basin discharge. The downstream location(235) is
approximately 3.0 miles downstream of the AS ash basin discharge.
Sampling and Analytical Methods
Grab samples collected from the surface(0.3 m) of the upstream and downstream locations in Lake
Wylie were analyzed for the following parameters: arsenic(As), cadmium(Cd), chromium(Cr), copper
(Cu), mercury(Hg), lead(Pb), selenium(Se),zinc(Zn), and total dissolved solids (TDS). Storage and
preservation techniques of the samples after collection, and prior to analyses,were followed according
to Appendix A. Analyses were conducted by Duke Energy's Huntersville analytical laboratory(NC
Wastewater Certification#248). Methods of analysis and results for each parameter are in Table 1.
Results/Recommendations
Most of the analytical results upstream and downstream of the ash basin discharge with the exception of
copper and zinc are at, or near,the method detection limits and below 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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Figure 1. Map of Lake Wylie with ash basin discharge and in -stream monitoring locations
depicted.

Appendix A
Sample Preservation and Hold times

parameter name Containerl Preservation2 3 Maximum
noldina time
Table 1BihOrgali Tests:
1.Acidity P,FP,G Cool,56°C18 14 days.
2.Alkalinity P,FP,G Cool,56°C18 14 days.
4.Ammonia P,FP,G Cool,56°CrB,H2SO4 to pH<2 28 days.
9.Biochemical Oxygen demand P.FP,G Cool,56°C18 48 hours.
10.Boron P,FP,or Quartz HNO3 to pH<2 6 months.
11.Bromide P,FP,G None required 28 days.
14.Biochemical oxygen demand,carbonaceous P,FP G Cool,56°C18 48 hours.
15.Chemical oxygen demand P,FP,G Cool,56'Ct8,HTSO,,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'C18 48 hours.
23-24.Cyanide,total or available(or CATC)and P,FP,G Cool,56°C18,NaOH to pH 14 days.
free >1056,reducing agent if
oxidizer present
25.Fluoride P None required 28 days.
27.Hardness P,FP,0 HNO3 or HaSQ06;PHH,<2 6 months.
28.Hydrogen ion(pH) P,FP,G None required Analyze within 15
minutes.
31,43.Kjeldahl iiiidiiiiiiiic N P.FP.0 Co9T`S¢',CC tb <2 28 days.
Table IB—Metals:'
18.Chromium VI P.FP,0 Cool,56'Cts pH*.93:9.72Q 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 days.'
lined cap" BrCl17
3,5-8,12,13,19,20,22,26,29,30,32-34,36,37, P,FP,G HNO3 to pH<2,or at least 24 6 months.
45,47,51,52,58-60,62,63,70-72,74,75.Metals, hours prior to analysis19
except boron,chromium VI,and mercury
38.Nitrate P,FP,G Cool,56°Ct6 48 hors.
39.Nitrate-nitrite P,FP,G Cool,56°C18,H2SO4 to pH<2 28 days.
40.Nitrite P,FP,G Cool,56°C18 48 NOV.
41.Oil and grease G Cool to 56°C16,HCI or H2SO4 28 days.
to pH<2
42.Organic Carbon P,FP,G Cool to 56'C1',HCI,H2SO4, 28 days.
or H3PO4 to pH<2
44.Orthophosphate P,FP,G Cool,to 56°C1824 Filter within 15
minutes;Analyze
within 48 hours.
46.Oxygen,Dissolved Probe G,Bottle and top None required Analyze within 15
minutes.
47.Winkler G,Bottle and top Fix on site and store in dark 8 hours.
48.Phenols G Cool,56°C16,H2SO4 to pH<2 28 days.
49.Phosphorous(elemental) G Cool,56°C18 48 hours.
50.Phosphorous,total P.FP,G Cool,56°C18,Hi.SO4jci pH<2 28 days.
53.Residue,total P,FP,G Cool,s6°C18 7 days.
54.Residue,Filterable P,FP,G Cool,s6°Ct8 7 days.
55.Residue,Nonfilterable(TSS) P,FP,G Cool,s6°C18 7 days.
56.Residue,Settleable P,FP.G Cool,56°C18 48 hours.
57.Residue,Volatile P,FP,G Cool,56°C18 7 days.
61.Silica P or Wertz Cool,56°Ct8 28 days.
64.Specific conductance P,FP,G Cool,56°C18 28 days.
95.Sulfate P.FP,0 Cool,56°Ct0 28 days.
66.Sulfide P,FP,G Cool,56°C18,add zinc 7 days.
acetate plus sodium hydroxide
to pH>9
67.Sulfite P,FP,G None required Analyze within 15
minutes.
68.Surfactants P,FP,G Cool,56°C18 48 hours.
69.TemPeratum P,FP,G None required Analyze.
73.Turbidity P,FP,G Cool,56°C18 48 hours.
'"P"is for polyethylene;"FP"is fluoropolymer(polytetrafluoroethylene(PTFE);Teflon"),or other fluoropolymer,unless stated
otherwise in this Table II;"G"is glass;"PA"is any plastic that is made of a sterilizable material(polypropylene or other autocavable
plastic);"LDPE"is low density polyethylene.
2Except where noted in this Table II 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(gx7Hi)or 40 CFR Part 403,Appendix E),refrigerate the sample at 56°C during collection unless specified otherwise in this

Table II 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 II 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 procedures,see EPA Method 1664 Rev.A(oil and grease)and
the procedures at 40 CFR 141.34(f)(14Xiv)and(v)(volatile organics).
3When 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 Table II, 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).
`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(gX7)(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.
5ASTM 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 21st editions)addresses dechlorination procedures.
(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.
'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(gx7xi)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.
(Guidance applies to samples to be analyzed by GC,LC,or GC/MS for specific compounds.
°If the sample is not adjusted to pH 2,then the sample must be analyzed within seven days of sampling.
10The 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.
"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 56°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 thiosulfate reduction),and footnotes
12,13(regarding the analysis of benzidine).
elf 1,2-diphenylhydrazine is likely to be present, adjust the pH of the sample to 4.0 ±0.2 to prevent rearrangement to
benzidine.
13Extracts may be stored up to 30 days at<0°C.
14For the analysis of diphenylnitrosamine, add 0.008% Na2S2O3 and adjust pH to 7-10 with NaOH within 24 hours of
sampling.
"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.
16Place 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.
"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.
"Aqueous samples must be preserved at 56°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"5°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).
1BAn 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.
20To 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.
21Holding 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.
22Sample analysis should begin as soon as possible after receipt;sample incubation must be started no later than 8 hours
from time of collection.
23For 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.
24The 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

Ash Basin Capacity Calculations

Duke Energy Company
Allen Steam Station -Ash Basin Forecasting
2014 Wet Weather Detention Volume Calculation
Determination of Wet Weather Detention Volume: Wet Weather Detention Volume is the sum of the
runoff accumulated in the ash basin which results from a 10-yr 24-hr storm (assuming 100% runoff)plus
the maximum 24-hr dry weather waste stream which discharges to the Ash Basin (refer to NPDES Permit
NC0004979)
I. Estimate Runoff to the Ash Basin from a 10-yr 24-hr storm:
1. Natural Drainage Area of Ash Basin= 288.0 Acres
Station Yard Drainage Area Pumped to Ash Basin= 40.0 Acres
Total= 328.0 Acres
2. Precipitation from 10-yr 24-hr storm= 5.0 Inches
3. Total Stormwater Runoff to Ash Basin= 136.67 Acre-feet
(Assuming 100%runoff)
II. Estimated Maximum 24-hr Dry Weather Waste Stream Discharging to Ash Basin:
1. Maximum recorded Ash Basin Discharge= 21,000,000 Gallons/day
2. Increase maximum daily disharge by 10%for
conservatism and convert units to acre-feet= 70.89 Acre-feet
III. Wet Weather Detention Volume:
Sum of Parts I.and II.= 207.55 Acre-feet
IV. Estimated Quantity of Solids(Ash)to be discharged to Ash Basin through December 31,2020.
Note: NPDES Permit expiration date is 5/31/2015.
Time Period Actual or %Ash Estimated Estimated Ash Estimated Estimated
Estimated Total Ash Sent to Ash Ash
Coal Production Structural Fill Discharged Discharged
Consumption (1000's tons) or Lined Land to Ash basin to Ash basin
(1000's tons) Fill(1000's (1000's tons) (Acre-feet)
bons)
2014(Jun-Dec) 848.41 10.00% 84.84 72.11 12.73 10.62
2015 1283.88 10.00% 128.39 109.13 1926 16.08
2016 489.32 10.00% 48.93 41.59 7.34 6.13
2017 232.88 10.00% 2329 19.79 3.49 2.92
2018 107.53 10.00% 10.75 9.14 1.61 1.35
2019 47.95 10.00% 4.80 4.08 0.72 0.60
2020 77.74 10.00% 7.77 6.61 1.17 0.97
Total 3087.71 10.00% 308.77 262.46 46.32 38.66
* Calculation assumes an in-place ash density of 55 lbs. per cubic foot.

Duke Energy Company
Allen Steam Station -Ash Basin Forecasting
2014 Wet Weather Detention Volume Calculation
V. Estimated Total Storage Volume Required through 2015:
Wet Weather Detention Volume= 207.6 Acre-feet
Estimated Solids to Ash Basin= 38.7 Acre-feet
Required Storage Volume Through 12/31/2020= 246.2 Acre-feet
VI. Results:
Ash Basin @ Pond Elevation 644'+0" = 672.5 Acre-feet
Total Available Storage= 672.5 Acre-feet
Note: Available Storage based on basin survey dated 7/18/2014
Available Storage>Required Storage
Based on these calculations,there is sufficient capacity in the ash basin to provide the retention
volume specified in the permit through the year 2020.