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DIVISION OF SURFACE WATER



# Antidegradation Addendum

In accordance with Ohio Administrative Code 3745-1-05 (Antidegradation), additiona l information may be required to complete your application for a permit to install o r N P DES permit. For any application that may result in an increase in the level o f pollut ants being discharged (NPDES and/or PTI)or for which there might be activit y taking place within a stream bed, the processing of the permit(s) may be required to go through procedures as outlined in the antidegradation rule. The rule outline s procedures for public not ification and participation as well as procedures pertaining to the levels of review necessary. The levels of review necessary depend on th e degradat ion being considered/requested. The rule also outlines exclusions fro m portions of the applicati on and review requirements and waivers that the Director may grant as specified in Section 3745-1-05(D) of the rule. Please complete the following questions. The answers provided will allow the Ohio EPA to determine if additiona l information is needed. All projects that require both an NPDES and PTI should submit both a p plications simultaneously to avoid going through the antidegradation proces s separately for each permit

.

A. Applicant:

Facility Owner:

Facility Location (city and county):

Application or Plans Prepared By:

Project Name:

NPDES Permit Number (if applicable):

B. Antidegradation Applicability

Is the application for? (check as many as apply):

Application with no direct surface water discharge (Projects that do not meet the applicability section of 3745-1-05(B)1, i.e., on-site disposal, extensions of s anitary sewers, spray irrigation, indirect discharger to POTW, etc.). (Complete Section E)

Rene wal NPDES application or PTI application with no requeste d increase in loading of currently permitted pollutants. (Complet e Section E, Do not complete Sections C or D).
PTI and NPDES application for a new wastewater treatment works that will discharge to a surface water. (Complete Sections C and E)
An expansion/modification of an existing wastewater treatment works disc harging to a surface water that will result in any of th e following (PTI and NPDES):(Complete Section s C and E) addition of any pollutant not currently in the discharge, or

an incr ease in mass or concentration of any pollutan t currently in the discharge, or

an incr ease in any current pollutant limitation in terms o f mass or concentration.

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PTI that involves placement of fill or installation of any portion of a se werage system (i.e., sanitary sewers, pump stations, WWTP , etc.) within 150 feet of a stream bed. Please provide informatio n requested on the stream e valuation addendum (i.e., number of stream crossings, fill placement, etc.) and complete S ection E.

Init ial NPDES permit for an existing treatment works with a wastewater discharge prio r to October 1, 1996. (Complete Sections D and E)

Renewal NPDES permit or modification to an effective NPDES permi t that will result in any o f the following:(Complete Section s C and E) a new permit limitation for a pollutant that previ ously had no limitation, or

an i n crease in any mass or concentration limitation of an y pollutant that currently has a limitation.

C. Antidegradation Information

1. Does the PTI and/or NPDES permit application meet an exclusion as outlined by OAC 3745-1-05(D)(1) of the Antidegradation rule?
Yes (Complete Question C.2)
No (Complete Questions C.3 and C.4)

2. For projects that would be eligible for exclusions provide the following information:

a. Provide justification for the exclusion.

b. Identif y the substances to be discharged, including the amount o f

r e gulated pollutants to be discharged in terms of mass an d concentration.

c. A description of any cons truction work, fill or other structures to occur or be placed in or near a stream bed.

3. Are you requesting a waiver as outlined by OAC 3745-1-05(D)(2-7) of th e Antidegradation rule?

No

Yes
If you wish to pursue one of the waivers, please identify the waiver and submit the necessary information to support the re quest. Depending on the waiver requested, the information required under question C.4 may b e required to complete the application.

4. For a ll projects that do not qualify for an exclusion a report mus t
acco mpany this application evaluating the preferred design alternative , non-degradation alternatives, minimal degradation alternatives, an d mitiga tive techniques/measures for the design and operation of th e activity. The information outlined below should be addressed in thi s report. If a waiver is requested, this section is still required.

a. Describe the availability, cost effectiveness and technica l f e asibility of connecting to existing central or regional sewag e collection and treatment facilities, including long range plans for

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sewer s ervice outlined in state or local water quality managemen t planning documents and applicable facility planning documents.

b. List and describe all government and/or privately sponsore d
conse rvation projects that may have been or will be specificall y targeted to improve water quality or enhance recreationa l opportunities on the a ffected water resource.

c. Provide a brief description below of all treatment/disposa l alternatives evaluated for this application and the i r respectiv e operational and maintenance needs. (If additional space is needed please attach additional sheets to the end of this addendum).
Preferred design alternative:

Non-degradation alternative(s):

Minimal degradation alternative(s):

Mitigative technique/measure(s):

At a minimum, the following information must be in c luded in the report for each alternative evaluated.

d. Outl ine of the treatment/disposal system evaluated, including th e costs associated with the equipment, installation, and continue d operation and maintenance.

e. Identif y the substances to be discharged, including the amount o f

r e gulated pollutants to be discharged in terms of mass an d concentration.

f. Describe the reliability of the treatment/disposal system, including but not limited to the possibility of recurring operation an d maintenance difficulties that would lead to increased degradation.

g. Describe any impacts to human health and the overall quality an d value of the water resource.

h. Descri be and provide an estimate of the important social an d
ec o nomic benefits to be realized through this proposed project

. Inclu de the number and types of jobs created and tax revenue s generated.

i. Describe environmental benefits to be realized th r o ugh this proposed project.
j. Describe and pr ovide an estimate of the social and economic benefits that may be lost as a result of this project. Include the impacts on commercial and recreational use of the water resource.

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k. Descri be the environmental benefits lost as a result of thi s project. Include the impact on the aquatic life, wildlife , threatened or endangered species.

l. A description of any cons truction work, fill or other structures to occur or be placed in or near a stream bed.

m. Provide any other informa tion that may be useful in evaluating this application.

D. Discharge Information

1. For treatment/disposal systems constructed pursuan t to a previously issued Ohio EPA PTI, provide the following information:

PTI Number PTI Issuance Date Initial Date of Discharge

2. Has the appropriate NPDES permit application form been submitted including representative effluent data?

Yes (go to E)

No (see below)

If no , submit the information as applicable under a OR b as follows:

a. For entities discharging process wastewater attach a completed 2C form.

b. For entities discharging wastewater of domestic origin attach th e results of at least one chemical analysis of the w astestream for all pollutants for which authorization to discharge is being requested and a measurement of the daily volume (gallons per day) o f wastewaters being discharged.

E. Based on my inquiry of the person or persons who manage the system or thos e persons directly responsi ble for gathering the information, the information is, to the best of my knowledge and belief, true, accurate and complete.

This section must be signed by the same responsible person who signed th e accompanying permit application or certification as per 40 CFR 122.22.

Signature

Date

h:revised.adm June 30, 1997

### Antidegradation Study Wastewater Treatment and Disposal Alternatives

Miami Fort Station – Units 7 & 8 Wet FGD System Retrofit Project North Bend, Hamilton County, Ohio

Prepared for: Duke Energy Ohio, Inc. Cincinnati, Ohio

October 7, 2008 Revision No. 1.1 Project No. 10444-712

Prepared by: Sargent & Lundy, L.L.C.

55 East Monroe Street Chicago, IL 60603-5780 USA

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 2 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 Table of Contents
Table of Contents.............................................................................................................. ........................2
List of Exhibits............................................................................................................... ...........................2
Introduction................................................................................................................... ..............................3
De Minimis Net Inc rease Exclusion.............................................................................................. .............3 Estimated Discharges........................................................................................................... .....................3
Exclusion Justification ........................................................................................................ ......................3
In-Stream Construction Activities .............................................................................................. ..............4 Antidegradation Evaluation for Boron........................................................................................... ..........4 Central or Regional Treatment Facilities ....................................................................................... ...........4 Conservation Projects .......................................................................................................... .....................5 Treatment and Disposal Alternatives............................................................................................ ............5 Preferred Design Alternative ................................................................................................... .............5 Non-Degradation Alternative.................................................................................................... ............6 Minimal Degradation Alternatives............................................................................................... .........7 Mitigative Technique and Measures.............................................................................................. .......8 Other Antidegradation Issues................................................................................................... .................8 Impacts to Human Health and Water Resources...................................................................................8
Social and Economic Benefits ................................................................................................... ...........8
Environmental Benefits ......................................................................................................... ...............9
Social and Economic Losses..................................................................................................... ............9
Environmental Benefits Lost .................................................................................................... ............9
In-Stream Construction Activities .............................................................................................. ........10
Conclusions.................................................................................................................... ............................10

List of Exhibits Exhibit 1 Estimated Discharge Exhibit 2 Net Increase Evaluation Input Data Exhibit 3 Determination of App licable De Minimis Thresholds
Exhibit 4 Net Increase Evaluation

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 3 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 INTRODUCTION
Sargent & Lundy, L.L.C. (Sargent & Lundy), on the behalf of Duke Energy Ohio, Inc. (Duke), has performed an antidegradation study to support the NPD ES Permit renewal application for the Miami Fort Generating Station, specifically addressing wastewater treatment and disposal associated with the Wet FGD System Retrofit Project.
The Ohio Environmental Protection Agency’s (EPA) Antidegradation Rule [Ohio Administrative Code (OAC) 3745-1-05 Antidegradation] generally applies to all new or increased discharges from wastewater treatment facilities into surface waters of the state. For an existing source like Miami Fort, the Ohio EPA Antidegradation Rule generally applies to the re-i ssuance of an NPDES that would result in any net increase of a regulated pollutant. Because the Wet FGD System Retrofit Project will result in a small net increase in the loading of regulated pollutants, th e Antidegradation Rule applies to the NPDES Permit renewal.
The first part of the antidegradation study deals with analysis of the wastewater discharge quality and comparison with applicable water quality criteria, st ream data, and calculated wasteload allocations, to determine which pollutants qualify for an exclusion fr om the antidegradation requirements because of a de minimis net increase, that which is less than 10% of the wasteload allocation. Thirty two regulated pollutants are evaluated. The second part of the antid egradation study provides an analysis of treatment and disposal options for boron, the only regulated pol lutant of the 32 pollutant s evaluated that exceeded the de minimis threshold.

DE MINIMIS NET INCREASE EXCLUSION
Estimated Discharge Sargent & Lundy estimated the amount of 32 regul ated pollutants for which the Wet FGD System Retrofit Project could result in a new or increased discharge. Exhibit 1 provides the amount of the 32 regulated pollutants that are discharged as a result of the Wet FGD System Retrofit Project, based on an analysis of actual effluent data , in terms of concentration.

Exclusion Justification For general high quality waters, such as the Ohio Rive r, a de minimis net increase in the discharge of a regulated pollutant, that which is less than 10% of the wasteload allocation (WLA), is excluded from the Ohio EPA antidegradation submittal and review requirements, provided the proposed lowering of water quality does not exceed 80% of the WLA.
Sargent & Lundy evaluated 32 regulated pollutants for which the Wet FGD System Retrofit Project could result in a new or increased discharge, following the requirements of the Ohio EPA Antidegradation Rule and published guidance documents. Exhibit 2 provides a detailed listing of input data used in the evaluation. Exhibit 3 provides additional input da ta, such as applicable water quality criteria and background water quality, and the calculated wasteload allocation and de minimis threshold for each of the 32 regulated pollutants.

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 4 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 The de minimis net increase exclusion evaluation included the following steps:

• Determination of the net wasteload increase as a result of the wet FGD process, and the total wasteload being discharged after the increase (Exhibit 1);

• Determination of the applicable water quality criteri a (WQC) at the point of the discharge (Exhibit 3);

• Tabulation of the background pollutant load, based on available backgrou nd water quality data, for each regulated pollutant (Exhibit 3);

• Calculation of the wasteload allocation (WLA) required to maintain water quality standards, calculated using Ohio EPA total maximum daily load procedures, for each WQC (Exhibit 3);

• Determination of both the 10% WLA threshold and the 80% WLA threshold for the lowest applicable WQC for each regulated pollutant (Exhibit 3); and finally,

• Comparison (Exhibit 4) of:

– The net wasteload increase to the 10% WLA threshold; and,

– The total wasteload to the 80% WLA threshold.
Of the 32 regulated pollutants, only one parameter, boron, exceeds the 10% WLA threshold. None of the 32 parameters exceed the 80% WLA threshold. Ther efore, based on the exclusion at OAC 3745-1-05 (D)(1)(b)(i) for general high quality waters, the disch arge of all regulated pollutants except boron is excluded from the submittal and review require ments in the Ohio EPA Antidegradation Rule.

In-Stream Construction Activities Construction of the Preferred Design Alternative fo r wastewater treatment and disposal, which is described below, did not include any construction work, fill or other structures in or near a stream bed. The Wet FGD System Retrofit Project itself required construction work, fill and mooring structures in the Ohio River and adjacent wetlands. This aspect of the Project was addressed in the applications for a 404 Permit and a 401 Water Quality Certification, and in the antidegradation assessment submitted with the 401 application.

ANTIDEGRADATION EVALUATION FOR BORON
This section of the Miami Fort antidegradation stud y evaluates the Preferred Design Alternative, NonDegradation Alternatives, Minimal Degradation A lternatives, and Mitigative Techniques and Measures for the design and operation of the Wet FGD Retr ofit Project. This section specifically addresses the treatment, disposal and discharge of boron, the single regulated pollutant that does not qualify for the de minimis discharge exclusion.
Central or Regional Treatment Facilities The wastewater stream from the Wet FGD Retrofit Project is treated and discharged via the existing Miami Fort wastewater treatment system (e.g. th e existing Ash Basins) to existing Outfall No. 002. Therefore, the project has not resulted in the creation of an additional new point source.

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 5 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 The plant is not located close to any other central or regional sewage collection and treatment facilities. The nearest publicly owned treatment facility is th e Indian Creek WWTP, operated by the Metropolitan Sewer District of Greater Cincinnati (MSD), which is located approximately 3.5 miles from the Miami Fort Station.
Conservation Projects There are no known government or privately sponsored conservation projects that may have been or will be specifically targeted to improve water quality of the Ohio River or it’s tributaries with respect to boron. There are, however, several projects intended to improve general water quality and to enhance the recreational opportunities of the affected water resources.
For example, Oxbow, Inc. (Oxbow) is a Cincinna ti-based wetland preservation organization that was established to protect seasonal wetlands and floodplai ns from development along the Great Miami River and Ohio River. To date, Oxbow has acquired 960 acr es of fee title or easement property within these two river basins. Duke and the Miami Fort Generating Station have demonstrated their commitment to preserving wetland areas near the station by donating a 20-acre parcel of land on the east side of an island located in the mouth of the Great Mi ami River to Oxbow in perpetuity.
Treatment and Disposal Alternatives Preferred Design Alternative System DescriptionThe Preferred Design Alternative for the FGD wastewater treatment system consists of a physicalchemical process to remove suspended solids and heavy metals. The treatment system consists of a series of reaction tanks that have the optimum mixing en ergy, retention time and chemical conditions to equilibrate the calcium sulfate in the wastewater and to render the various contaminants insoluble, using both hydroxide and sulfide precipitation. The preci pitated contaminants are then removed through clarification of the wastewater.
The preferred FGD wastewater treatme nt system is designed to treat 200 gallons per minute (gpm), which is approximately 125% of the combined wet FGD bl eed stream from both wet FGD systems. The design basis raw wastewater quality is based on the characteristics of the coal, limestone, makeup water and cycles of concentration associated with an FGD chloride limit of 20,000 parts per million (ppm).
The physical-chemical treatment system includes the following processes:

• Wastewater equalization

• Gypsum desaturation, with sludge reci rculation to aid desaturation process

• Hydroxide precipitation of heavy metals, using lime

• Sulfide precipitation of heavy metals, using an organosulfide compound or sodium hydrosulfide

• Coagulation with ferric chloride

• Polymer dosing to aid flocculation

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 6 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 • Clarification

• Sludge dewatering with plate and frame filter presses

Treated effluent from the FGD wastewater treatment system is pumped to the existing Ash Basins. The Ash Basins are designed to manage several wastewat er streams, and provide settling prior to discharge through Outfall No. 002 to the Ohio River. The f ilter cake produced by the FGD wastewater treatment system consists primarily of gypsum solids and lim estone inert solids which are trucked offsite for disposal at a properly permitted landfill.
System Costs The actual cost for the Preferred Design Alternative for treatment and disposal of FGD wastewater is $11 million. The cost includes approximately $5.5 m illion for equipment and materials, $3.3 million for labor, and $2.2 million for constr uction management, subcontractor indirects, engineering, and miscellaneous project costs. The estimated annual ope rating cost for the treatment system is $800,000, which includes chemicals, contract labor, sludge disposal and maintenance parts.

Boron Removal The Preferred Design Alternative for treatment and disposal of FGD wastewater successfully removes substantial amounts of most of the 32 regulated pollutants. The system, however, only removes approximately 10% of the boron entering the system. Th e exact mechanism of this removal is not known. Boron is known in the power and wast ewater treatment industries to be difficult to remove from process streams.
Reliability and O&M Issues There are approximately a twelve treatment systems of this type operating in the U.S. and 36 operating in Europe. Available data shows that hydroxide a nd organosulfide wastewater treatment systems consistently remove most metals to very low levels.
The operation of the Preferred Design Alternative requi res 11⁄2 operators during the day shift and 1⁄2 of an operator during the night shift. The chemicals used in this type of plant are common industrial chemicals and readily available. The solid w aste from the preferred system is disposed of in a properly permitted landfill.
Non-Degradation Alternative System Description The Non-Degradation Alternative is to add a zero-li quid discharge (ZLD) system to the Preferred Design Alternative to achieve a near-zero discharge of boron. The ZLD system would consist of a brine concentrator and a brine crystallizer to further treat the 200-gpm effluent from the heavy metals precipitation process. The ZLD process would produce approximately 196 gpm of distillate for reuse and a salt cake for disposal, so no liquid wastewater w ould be discharged. Other zero-discharge technology options, such as evaporation ponds or ion exchange processes, are either not technically feasible for Miami Fort or are not commercially proven at this time.

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Sargent & Lundy, L.L.C. Project No. 10444-712 The ZLD treatment system would include the following processes:

• Regenerative feedwater preheater;

• Deaerator to remove dissolved gases;

• Brine concentrator to initiate crystal growth;

• Brine crystallizer to produce a concentrated slurry of salt crystals;

• Rotary dryer to minimize the moisture in the slurry and produce the salt cake;

• Auxiliary boiler to provide steam to the brine concentrator; and

• Fabric filter collector to remove fine soli d particles from the rotary dryer’s exhaust.

The selection of the brine concentrator option involves several processes and waste management activities. Essentially, this alternativ e results in “zero liquid discharge”. All constituents of the Miami Fort FGD wastewater would be removed: Borates and othe r dissolved salts, trace metals (both dissolved and particulate), and suspended solids. Because this option seeks to achieve “zero liquid discharge”, considerable amounts of solid waste would need to be disposed of in properly permitted landfills. The effluent water produced by the system will be of suffici ent high-quality to be reused in the plant, rather than discharged. System Costs The estimated total cost for the Non-Degrada tion Alternative is $37.8 million, which includes $13.0 million for equipment and materials and $24. 8 million for labor, construction management, subcontractor indirects, engineering, and miscellane ous project costs. The equipment costs include the evaporator, crystallizer, dewatering equipment and the auxiliary boiler. The miscellaneous project costs include site-specific site development costs for the Miami Fort station. The estimated annual operating cost for the Non-Degradation Alternative is $2.5 million.
Boron Removal A wastewater treatment system that incorporates a brine concentrator will not discharge any boron. Any boron in the wastewater will be concentrated in to a solid form for disposal in a landfill.
Reliability and O&M Issues Brine concentrator treatment syst ems are known for having significant operation and maintenance issues. The operation of brine concentrators typically requir es 4 to 5 dedicated trained operators and a managing engineer whose sole job is troubleshooting the equipmen t. Due to the down-time associated with this type of system and the inability of the generating plant to operate without a working brine concentrator, the ability of the Miami Fort Station to produce electric power would be closely tied to brine concentrator availability.
Minimal Degradation Alternatives Minimal degradation alternatives are treatment and di sposal alternatives, including pollution prevention alternatives, that would result in a lesser lowe ring of water quality with respect to boron.

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 8 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 There is a general consensus in the power and wastew ater treatment industries that boron treatment is very difficult, if not technically infeasible for many applications. Wastewater treatment options, including selective ion-exchange, hot or cold lime softening, bioremediation, precipitation, and adsorption, are mentioned in the literature, but the references are few and the results are conflicting. Lab and pilot studies are needed to verify the performa nce of these processes. As a result, there are no commercially available treatment technologies capable of removing significan t amounts of boron that do not have impractical construction costs and requirements, high operating costs, or the creation of significant waste streams.
There are no known pollution prevention alternatives to reduce boron in the FGD wastewater stream. The presence of boron in the wastewater is a fundamental r esult of the scrubbing of the plant’s flue gas in the FGD system.
Mitigative Techniques and Measures Mitigative Techniques and Measures include alternativ e on-site or off-site cont rol measures designed to offset all or part of the lowering of water quality with respect to boron, preferably within the same watershed. No such mitigative techniques or measures are proposed for this project, due, in part, to the fact that boron is not generally considered to be present at significant levels in the Ohio River or the watershed. Furthermore, as previously discussed, bor on is extremely difficult to treat from any source.
Duke has demonstrated its commitment to preser ving wetlands and improving water quality near the Miami Fort Generating Station, through its suppor t of the Oxbow organization, as discussed above.
Other Antidegradation Issues Impacts to Human Health and Water Resources The Wet FGD System Retrofit Project with the Preferred Design Alternative for wastewater treatment will result in a very minor lowering of water quality w ith respect to boron, but should have no impact to human health, overall water quality or the value of th e water resource. The lowering of water quality will not result, either individually or cumulatively with other discharges, in the ex ceedance of any applicable water quality standards, including human health, agricu ltural use, and aquatic life, or interfere with the achievement of any designated beneficial uses of the Ohio River.
Social and Economic Benefits The Miami Fort Generating Station site has been criti cal to the long-term generation of electric power in southwestern Ohio since the 1920’s. The need for electric power has increas ed with the increased urbanization and development of the service region. Gi ven the site history and increased regional need for electricity, it would be economically infeasible to move the existing generating operations to a site remote from the existing location. The Wet FGD System Retr ofit Project has had a substantial positive impact on maintaining the ability of the plant to continue to meet the electric power needs of the region as well as meeting the increasingly stringent air quality requirements.
The Wet FGD System Retrofit Project increased the tax assets of the Miami Fort Generating Station property and provides potential future tax incentives. Additionally, the project has the potential to increase the property values of the surrounding parcels as a result of improved ambient air quality.

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 9 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 Construction of the Project has had a positive impact on the local economy, as a result of the jobs and state income tax revenues that were generated, local trade for goods and services that occurred (e.g. food, fuel, lodging, etc.), and the local materials that we re required for construction activities. The original estimated tax income is provided in the following table.

Item Calculation Basis Estimated Tax Income Construction Jobs Created 250 jobs x 2,000 hours x 2 years x $25/hour = $25,000,000 $1,125,000

Permanent Staff Created 6 jobs x 2,000 hours x 30 years x $35/hour = $12,600,000 $567,000

TOTAL $1,692,000

Environmental Benefits Since being placed in operation, the Wet FGD System Retrofit Project has substantially reduced air emissions of sulfur dioxide (SO 2 

### ), acid gases, and metals, such as mercury, from the Miami Fort Generating Station, thereby improving air quality within the greater tri-state region and the Ohio River Valley. From an air quality standpoint, the implemen tation of the Project with the Preferred Design Alternative has had a significant positive environmental impact on the environment and the overall health of people living and working within in the southwest Ohio region.

Social and Economic Losses There have been no jobs or revenues lost from th e implementation of the Wet FGD System Retrofit Project with the Preferred Design Alternative. The commercial and recreational uses of the Ohio River have not been impacted by the project. The constructi on, operation, and maintenance of the project have had positive impacts to the socioeconomic characteristi cs of the project area (see Social and Economic Benefits, above).
Environmental Benefits Lost No existing environmental benefits have been lost as a result of the implementation of the project with the Preferred Design Alternative, nor would any be lo st as a result of the implementation of the NonDegradation Alternative. The existing uses of the Oh io River have been and would be maintained. The project has not had an impact on aquatic life, wildlife, threatened or endangered species.
As discussed above, the Wet FGD System Retrofit Proj ect itself required construction work, fill and other structures in the Ohio River and adjacent wetlands . This aspect of the Project was addressed in applications for a 404 permit and a 401 Water Qua lity Certification, including the antidegradation assessment submitted with the 401 application. Neith er the Preferred Design Alternative nor the NonDegradation Alternative would result in additional impacts.

### Duke Energy Ohio, Inc. Antidegradation Study Rev. 1.1 Miami Fort Station – Units 7 & 8 October 7, 2008 Wet FGD System Retrofit Project Page 10 of 10

Sargent & Lundy, L.L.C. Project No. 10444-712 Duke has evaluated threatened and endangered species habitat adjacent to the Ohio River and along Dark Hollow Creek, which flows to the Ohio River near the eastern boundary of the site. Based on an on-site monitoring program, literature review, and correspon dence with the Ohio Department of Natural Resources – Natural Areas and Preserves (ODNR-DNAP) and the U.S. Fish and Wildlife Service (USFWS), there are no unique habitats on the site nor is there indication of the presence of any threatened and endangered wildlife species.

In-Stream Construction Activities Construction of the Preferred Design Alternative for wastewater treatment and disposal did not include any construction work, fill or other structures in or near a stream bed. Due to the congestion of the Miami Fort site, the Non-Degradation Alternative would requ ire site development activities in or near the Ohio River stream bed.
As discussed above, the Wet FGD System Retrofit Proj ect itself required construction work, fill and other structures in the Ohio River and adjacent wetlands. This aspect of the Project was addressed in the application for a 401 Water Quality Certification, including the antidegradation assessment submitted with the 401 application.

CONCLUSIONS
The Wet FGD System Retrofit Project has had a subs tantial positive impact on maintaining the ability of the Miami Fort Generating Station to continue to m eet the electric power needs of the region as well as the applicable air quality requirements.
With the implementation of the Preferred Design A lternative, only one parameter, boron, out of 32 regulated pollutants evaluated by Sargent & Lundy, exceeds the 10% WLA threshold, and none of the 32 parameters exceed the 80% WLA threshold. Therefore, the discharge of all regulated pollutants except boron is excluded from the submittal and review re quirements in the Ohio EPA Antidegradation Rule.
The Preferred Design Alternative for the treatment a nd disposal of wastewater from the FGD system, a hydroxide and sulfide precipitation process for removal of metals, results in the least lowering of water quality with respect to all regulated pollutants, includ ing boron. There are no cost-beneficial, technically feasible, and commercially available treatment and di sposal alternatives that would result in a lesser lowering of water quality with respect to boron.Duke Energy Ohio, Inc. Miami Fort – Units 7 & 8 Wet FGD System Retrofit Project Exhibit 1 Estimated Discharge Anti-Degradation Study Rev. 1.1 10/7/2008 Page 1 of 1

Discharge Parameter Estimated Discharge

Parameter Units
Aluminum, total μ g/L 0.016 0.664 Ammonia, summer mg/L 0.017 0.1 Ammonia, winter mg/L 0.017 0.1 Antimony, total μ g/L 0.01 0.01 Arsenic, total μ g/L 37.56 37.56 Barium, total μ g/L 180.2 180.2 Beryllium, total μ g/L 0.000037 0.005 Boron, total μ g/L 3,601 4,418 Cadmium, total μ g/L 0.309 2.38 Chloride, total mg/L 90.06 147.5 Chromium, total μ g/L 0.495 7.67 Cobalt, total μ g/L 0.05 0.05 Copper, total μ g/L 6.19 10.8 Iron, total μ g/L 7.43 271 Lead, total μ g/L 0.198 9.5 Magnesium, total mg/L 50.68 70.74 Manganese, total μ g/L 0.134 0.184 Mercury, total μ g/L 0.0124 0.0172 Molybdenum, total μ g/L 0.00495 0.17 Nickel, total μ g/L 1.24 20.7 Nitrate + Nitrite mg/L 0.225 2.149 Nitrite mg/L 0.00124 0.115 Phosphorus, total mg/L 0.00495 0.1467 Selenium, total μ g/L 12.38 17.984 Silver, total μ g/L 0.005 0.005 Solids, dissolved mg/L 411.73 972 Sulfate, total mg/L 140.26 408.67 Thallium, total μ g/L 0.000111 0.01 Tin, total μ g/L 0.1 0.1 Titanium, total μ g/L 0.05 0.05 Vanadium, total μ g/L 0.198 25.5 Zinc, total μ g/L 0.470 27.9 Total Wasteload after Increase Net Wasteload Increase from FGD

Sargent & Lundy, L.L.C. Project No. 10444-712Duke Energy Ohio, Inc. Miami Fort – Units 7 & 8 Wet FGD System Retrofit Project Exhibit 2 Net Increase Evaluation Input Data Anti-Degradation Study Rev. 1.1 10/7/2008 Page 1 of 1

Parameter Season Value Basis

Stream Flows

1Q10 annual 8,670 cfs ORSANCO 2006 7Q10 annual 10,600 cfs " 7Q10 summer 10,600 cfs " 7Q10 winter 10,600 cfs " 30Q10 summer 10,600 cfs " 30Q10 winter 10,600 cfs " HMQ annual 45,300 cfs "

Mixing assumptions average 10% OAC 3745-2-05(A)(2)(f) maximum 1% "

Stream Water Quality Parameters

Instream hardness (H) annual 133.1 mg/L n=102 Instream pH summer 7.5 S.U. n=10 Instream pH winter 7.5 S.U. n=6 Instream temp summer 17 °C Instream temp winter 13 °C

Background Water Quality

Data See Exhibit 3 Data Source STORET: Station OR502.2M Ohio River at Anderson Ferry, OH Organization 31ORWUNT (ORSANCO) Available data, August 2008

Effluent Parameters

Discharge Flow - Outfall 002 average 23.05 cfs Miami Fort NPDES permit application 14.90 mgd

maximum 27.23 cfs Miami Fort NPDES permit application 17.60 mgd

Effluent hardness 400 mg/L Maximum hardness value per Table 7-9, footnote 6 (The reported average effluent hardness = 561 mg/L)

De minimis net increase exclusion

Receiving waters Ohio River at River Mile 490.5 Designated uses Agricultural water supply OAC 3745-1-32 Bathing waters " Industrial water supply " Public water supply " Warmwater habitat "

Antidegradation classification General high quality waters OAC 3745-1-05(A)(10)

De minimis net increase 10% % of WLA OAC 3745-1-05(D)(1)(b)(i) "Total impact limit" 80% % of WLA "

Sargent & Lundy, L.L.C. Project No. 10444-712Duke Energy Ohio, Inc.Miami Fort – Units 7 & 8Wet FGD System Retrofit ProjectExhibit 3Determination of Applicable De Minimis ThresholdsAnti-Degradation StudyRev. 1.110/7/2008Page 1 of 1Discharge Parameter Applicable Water Quality Criteria Background Pollutant Load Calculated Wasteload Allocations (WLA) ApplicableDe Minimis ThresholdsOutside Mixing ZoneOutside Mixing ZoneAverage Background Water Quality AverageParameter Units Human Health Agriculture Aquatic Life Value / Number of Samples Human Health Agriculture Aquatic Life Basis10% WLAThreshold80% WLAThresholdAluminum, totalμg/L -- -- -- -- -- 1209 n=48 -- -- -- -- -- -- -- -- --Ammonia, summer* mg/L -- -- 2.2 13 49 0.08778 n=27 -- -- 99 63 49 49 IMZM 4.9 39Ammonia, winter* mg/L -- -- 6.0 13 54 0.1371 n=28 -- -- 276 63 54 54 IMZM 5.4 43Antimony, totalμg/L 14 -- 190 900 1800 0.1388 n=48 6,388 -- 8,921 4,403 1,800 1,800 IMZM 180 1,440Arsenic, totalμg/L 50 100 150 340 680 1.214 n=54 22,485 19,514 6,992 1,659 680 680 IMZM 68 544Barium, totalμg/L -- -- 220 2,000 4,000 51.94 n=55 -- -- 7,949 9,583 4,000 4,000 IMZM 400 3,200Beryllium, totalμg/L 16 100 15 130 250 0 No Data Available 7,374 19,753 705 636 250 250 IMZM 25 200Boron, totalμg/L -- -- 950 8,500 17,000 0 No Data Available -- -- 44,638 41,589 17,000 17,000 IMZM 1,700 13,600Cadmium, total†μg/L -- 50 3.08 6.24 43.2 0.1050 n=63 -- 9,856 140 30 43 30 OMZM 3.0 24Chloride, total mg/L 250 -- -- -- -- 31.19 n=55 100,876 -- -- -- -- 100,876 OMZA 10,088 80,701Chromium, total†μg/L -- 100 109 2,279 11,223 2.251 n=55 -- 19,310 5,015 11,143 11,223 5,015 OMZA 502 4,012Cobalt, totalμg/L -- -- 24 220 440 0 No Data Available -- -- 1,128 1,076 440 440 IMZM 44 352Copper, total†μg/L 1300 500 11.9 18.3 103.4 3.731 n=63 597,415 98,031 388 75 103 75 OMZM 7.5 60Iron, totalμg/L -- 5000 -- -- -- 2183 n=63 -- 558,716 -- -- -- 558,716 OMZA 55,872 446,973Lead, total†μg/L -- 100 9.24 176 1,430 2.894 n=53 -- 19,184 301 851 1,430 301 OMZA 30 241Magnesium, total mg/L -- -- -- -- -- 10.98 n=63 -- -- -- -- -- -- -- -- --Manganese, totalμg/L -- -- -- -- -- 155.5 n=63 -- -- -- -- -- -- -- -- --Mercury, totalμg/L 0.012 10 0.91 1.7 3.4 0.005178 n=53 3.15 1,974 42.5 8.30 3.40 3.15 OMZA 0.31 2.52Molybdenum, totalμg/L -- -- 110 2,400 4,700 0 No Data Available -- -- 5,169 11,743 4,700 4,700 IMZM 470 3,760Nickel, total†μg/L 610 200 66.5 598 3,031 4.575 n=55 279,027 38,607 2,912 2,907 3,031 2,907 OMZM 291 2,325Nitrate + Nitrite mg/L 10 100 -- -- -- 1.052 n=55 4,125 19,546 -- -- -- 4,125 OMZA 412 3,300Nitrite mg/L 1.0 -- -- -- -- 0 No Data Available 461 -- -- -- -- 461 OMZA 46 369Phosphorus, total mg/L -- -- -- -- -- 0.1547 n=55 -- -- -- -- -- -- -- -- --Selenium, totalμg/L 170 50 5.0 -- -- 0.6190 n=55 78,063 9,755 206 -- -- 206 OMZA 21 165Silver, totalμg/L 50 -- 1.3 2.2 4.4 0.09365 n=55 23,000 -- 57 10 4.4 4.4 IMZM 0.44 3.5Solids, dissolved mg/L -- -- 1,500 -- -- 63 n=20 -- -- 67,583 -- -- 67,583 OMZA 6,758 54,067Sulfate, total mg/L 250 -- -- -- -- 69.07 n=55 83,456 -- -- -- -- 83,456 OMZA 8,346 66,764Thallium, totalμg/L 1.7 -- 17 79 160 0 Non-Detect 783 -- 799 387 160 160 IMZM 16 128Tin, totalμg/L -- -- -- -- -- 0 No Data Available -- -- -- -- -- -- -- -- --Titanium, totalμg/L -- -- -- -- -- 0 No Data Available -- -- -- -- -- -- -- -- --Vanadium, totalμg/L -- -- 44 150 300 0 No Data Available -- -- 2,067 734 300 300 IMZM 30 240Zinc, total†μg/L 9,100 25,000 153 153 776 14.86 n=62 4,187,080 4,935,311 6,491 689 776 689 OMZM 69 551* Aquatic life OMZA and OMZM are temperature and pH dependent Stream design flows and percentages [per 3745-2-05 (A)(2)(f)]:†Aquatic life OMZA, OMZM and IMZM are hardness (H) dependent:OMZA (human health) : 100% of 7Q10the OMZA and OMZM WQC are based on instream-H; IMZM WQC are based on effluent-H OMZA (agriculture) : 10% of HMQOMZA = outside mixing zone average.OMZA (aquatic life) : 10% of 7Q10OMZM = outside mixing zone maximum;OMZM (aquatic life) : 1% of 7Q10IMZM = inside mixing zone maximum;IMZM no mixing consideredLowestWasteloadAllocationMaximumAquatic LifeInside MixingZoneMaximumInside MixingZoneMaximumMaximumAquatic LifeSargent & Lundy, L.L.C.Project No. 10444-712Duke Energy Ohio, Inc. Miami Fort – Units 7 & 8 Wet FGD System Retrofit Project Exhibit 4 Net Increase Evaluation Anti-Degradation Study Rev. 1.1 10/7/2008 Page 1 of 1

Discharge Parameter Net Increase Evaluation

Parameter Units
Aluminum, total μ g/L 0.016 No 0.664 No Ammonia, summer mg/L 0.017 No 0.1 No Ammonia, winter mg/L 0.017 No 0.1 No Antimony, total μ g/L 0.01 No 0.01 No Arsenic, total μ g/L 37.56 No 37.56 No Barium, total μ g/L 180.2 No 180.2 No Beryllium, total μ g/L 0.000037 No 0.005 No Boron, total μ g/L 3,601 YES 4,418 No Cadmium, total μ g/L 0.309 No 2.38 No Chloride, total mg/L 90.06 No 147.5 No Chromium, total μ g/L 0.495 No 7.67 No Cobalt, total μ g/L 0.05 No 0.05 No Copper, total μ g/L 6.19 No 10.8 No Iron, total μ g/L 7.43 No 271 No Lead, total μ g/L 0.198 No 9.5 No Magnesium, total mg/L 50.68 No 70.74 No Manganese, total μ g/L 0.134 No 0.184 No Mercury, total μ g/L 0.0124 No 0.0172 No Molybdenum, total μ g/L 0.00495 No 0.17 No Nickel, total μ g/L 1.24 No 20.7 No Nitrate + Nitrite mg/L 0.225 No 2.149 No Nitrite mg/L 0.00124 No 0.115 No Phosphorus, total mg/L 0.00495 No 0.1467 No Selenium, total μ g/L 12.38 No 17.984 No Silver, total μ g/L 0.005 No 0.005 No Solids, dissolved mg/L 411.73 No 972 No Sulfate, total mg/L 140.26 No 408.67 No Thallium, total μ g/L 0.000111 No 0.01 No Tin, total μ g/L 0.1 No 0.1 No Titanium, total μ g/L 0.05 No 0.05 No Vanadium, total μ g/L 0.198 No 25.5 No Zinc, total μ g/L 0.470 No 27.9 No Exceeds 10% WLA Threshold? Exceeds 80% WLA Threshold? Total Wasteload after Increase Net Wasteload Increase from FGD

Sargent & Lundy, L.L.C. Project No. 10444-712