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## F ACT 

## S HEET
AND 

## P ERMIT 

## R ATIONALE 

### Rationale Page 1 of 44 Permit No. SC0001333



## Voridian August 23, 2004 

## NPDES Permit No. SC0001333

Permitting Engineer: Melanie Kastler

Facility Rating: Major (EPA review required) Minor (EPA review may be required; see below)

Permit application included in Appendix A.

Facility Address: P.O. Box 1782, Columbia SC 29202 (see map, Appendix E) County: Calhoun Watershed: Basin 02 (Saluda-Edisto River Basin)

Issuance (New) Reissuance Modification

If this application is for a new facility or expansion of an existing facility, an antidegradation review may be require d per the requirements of R.61-68.D.

Facility Description (include SIC code): This facility manufactures organic intermediates and plastic material, and co mpounds and extrudes specialty plastics. SIC Codes are 2865, 2821 and 3087.

Does this permit contain more than one out fall, including internal outfalls? Yes Outfalls will be listed in Section III of this rationale with a general description of the discharge, treatment system, stream flows and other pertinent information about each outfall.

→ Is any discharge subject to any of the Primary Industry Categories identified in R.61-9.122, Appendix A as listed at right? Yes (If yes, EPA review required.) Indicate category(ies) applicable and Regula tions governing the discharge: OCPSF, 40 CFR 410 Auto and other laundries

Coal mining Coil coating Copper forming Electrical and electronic components Electroplating Explosives manufacturing Foundries Gum and wood chemicals Inorganic chemicals manufacturing Iron and steel manufacturing Leather tanning and finishing Mechanical products manufacturing N onferrous metal manufacturing Ore mining

Paint and ink formulation Pesticides Petroleum refining

Photographic equipment and supplies Plastics processing

Printing and publishing

Rubber processing Soap and detergent manufacturing

Textile Mills Timber Products Processing Primary Industry Categories Adhesives and sealants Aluminum forming

Battery manufacturing

Organic chemicals manufacturing

Pharmaceutical preparations

Plastic and synthetic materials manufacturing Porcelain enameling

Pulp and paper mills

Steam electric power plants

Receiving Water: Internal Outfalls: 01A, 01B (proposed ), 01D, 01E, 01F, 01G and Outfall 001- Congaree River Receiving Water Classification (see R.61-69 for water classifications): Fresh Water

→ Does any discharge(s) have the potential to affect waters in another state? No (If yes, EPA review required.)

Is any discharge to Impaired Waters?: Yes If Yes, list the monitoring station number and parameter(s) causing impairment: Based on DHEC’s assessment of ambient monitoring data, C-074 is impaired for copper and fecal colifor m, C-007 is impaired for mercury and copper and Lake Marion is impaired for phosphorus at SC-008.

→ Average Discharge Flow from outfa ll with largest average flow: ( Q d ) (MGD): 92.31 (from permit application; including increase in production) (EPA review required for any average discharge exceeding 0.5 MGD)

→ Is this permit for a Federal facility with a daily average fl ow greater than 0.05 MGD (from all sources)? No (If yes, EPA review required.)

Data from Discharge Monitoring Reports (DMRs) and NPDES pe rmit application (including all subsequent data presented) from 1/31/00-1/31/04 has been used to evaluate permit limitations.

### Rationale Page 2 of 44 Permit No. SC0001333

I. GENERAL INFORMATION

A. The effluent from this facility may be subject to the re quirements of any of the following regulations: R.61-9.125, 129, 133, and 403; 40 CFR Part 136; Subchapter N (40 CFR Parts 400 through 402 and 404 through 471); R.61-9.503, R.61-9.504 and R.61-9.505.

B. Authority: This permit is written in accordance with app licable laws and regulations including, but not limited to, Regulation 61-9, Regulation 61-68, Polluti on Control Act and Clean Water Act.

C. Under R.61-9.124.8 (Fact Sheet), a fact sheet shall be prepared for every draft permit for a major NPDES fac ility or activity, for every Class I sludge management facility, for every NPDES draft permit that incorporates a variance or requires an explanation under section 124.56( b), and for every draft permit which the Department finds is the subject of wide-spread public interest or raises major issues.

D. The conclusions noted in the Rationale establish proposed effluent limitations and permit requirements addressed in R.61-9.122.43 (Establishing Permit Conditions), R.61-9.122.44 (Establishing Limitations, Standards and other permit conditions) and other appropr iate sections of R.61-9.

II. RATIONALE GUIDANCE PROCEDURES

A. The receiving waterbody 7Q10, annual average flow or othe r critical flow condition at the discharge point, and 7Q10, annual average flow, or other critical flow condition at the boundary of the source water protection area above a proposed or existing drinking water intake (if applicable ) are determined by the SCDHEC’s Wasteload Allocation Section. The 7Q10, Annual Average Flow or other criti cal flow conditions are based on information published or verified by the USGS, an estimate extrapolation from publishe d or verified USGS data or from data provided by the permittee. These flows may be adjusted by the Wast eload Allocation Section to account for existing water withdrawals that impact the flow. The 7Q10 (or 30Q5 if provided by the applicant), annual average flow at the discharge point, or other critical flow condition or 7Q10 (o r 30Q5 if provided by the applicant), annual average flow or other critical flow condition at the boundary of the SWP area for a proposed or existing drinking water intake will be used to determine dilution factors, as appropriate, in accordance with R.61-68.C.4.a & 4.b for aquatic life, human health, and organoleptic effects respectively.

B. Water and organism consumption a nd drinking water MCL data will be ev aluated as human health values when calculating dilution factors. “The Department may, after Notice of Intent included in a notice of a proposed NPDES permit in accordance with Regulation 61-9.124.10, determine that drinking water MCLs or W/O shall not apply to discharges to those waterbodies where there is: no potential to affect an existing or proposed drinking water source and no state-approved source water protection area.” Fo r permitting purposes, a proposed drinking water source is one for which a complete permit application, including plan s and specifications for the intake, is on file with the Department at the time of consideration of an NPDES perm it application for a discharge that will affect or has the potential to affect the drinking water source.” See R.61- 68.E.12.c(5). The Department defines the source water protection (SWP) area to be the primary SWP area delineated by the Source-Water Assessment and Protection (SWAP) Program initiated by the EPA and required by th e states to identify SWP areas to protect drinking water sources. Using the procedure described in the documen t entitled, “Determination of the Primary and Secondary Source-Water Protection Areas for Selected Surface-Water Public-Supply Systems in South Carolina, 1999,” USGS Water Resource Investigations Report 00-4097, the primary SWP area for a drinking water intake is the area which encompasses all 14-digit Hydrologic Unit Code (HUC) basins that adjoin streams, tributaries, and reservoirs between an intake and the upstream 10-percent exceedance, 24-hour travel distance (TOT 10 ). The entire basin above a drinking water intake has been designated as the SW P area where the drainage area is equal to or less than one HUC basin or is estimated to have less than 24-hours of instream travel tim e between the intake and the HUC basin in the headwaters of the drainage basin.

### Rationale Page 3 of 44 Permit No. SC0001333

C. Application of numeric criteria to protect human hea lth: If separate numeric criteria are given for organism consumption, water and organism c onsumption (W/O), and drinking water Maximum Contaminant Levels (MCLs), they shall be applied as appropriate. The most stringent of the criteria shall be applied to protect the existing and classified uses of the waters of the State. See R.61-68.E.12.b(1).

D. Numeric criteria have been established in R.61-68 based on organoleptic data (prevention of undesirable taste and odor). For those substances which have aquatic life a nd/or human health numeric criteria and organoleptic numeric criteria, the most stringent of the three shall be used for derivation of permit effluent limitations. See R.61-68.E.11.

E. Sampling Frequency: Samples and measurements taken for the purpose of monitoring shall be representative of the monitored activity. Monitoring results must be conducted according to test procedures approved under 40 CFR Part 136, unless other test procedures have been specified in the permit (R.61-9.122.41). Typically requirements to report monitoring results shall be est ablished on a case-by-case basis with a frequency dependent on the nature and effect of the discharge but in no case less than once a year (R.61-9.122.44)

F. Compliance Schedules:

1. A person issued an NPDES permit by the Department who is not in compliance with applicable effluent standards and limitations or other requirements contained therein at th e time the permit is issued, shall be required to achieve compliance within a period of time as set forth by the Depa rtment, with effluent standa rds and limitations, with water quality standards, or with specific requirements or conditions set by the Department. The Department shall require compliance with terms and conditions of the permit in the s hortest reasonable period of time as determined thereby or within a time schedule for compliance which sh all be specified in the issued permit.

2. If a time schedule for compliance specified in an NPD ES permit which is established by the Department, exceeds nine (9) months, the time schedule shall provide for inte rim dates of achievement for compliance with certain applicable terms and conditions of the permit. (R.61-9.122.47)

G. Procedure for establishing effluent limitations:

1. Effluent limits (mass and concentration) for Five day Biochemical Oxygen Demand (BOD 5 ), Ultimate Oxygen Demand (UOD), Dissolved Oxygen (DO), Total Ammonia Nitrogen (as N), and Nutrients are established by the Wasteload Allocation (WLA) Section, with cons ideration given to technology-based limitations.

a. Five day Biochemical Oxygen Demand BOD 5 , Ultimate Oxygen Demand UOD, Dissolved Oxygen DO:

Effluent limits for conventional oxygen demanding constituents (BOD 5 , UOD and DO) are established to protect in-stream water quality and uses, while utilizing a portion of the assimilative capacity of the receiving water. The ability of a water body to assimilate oxy gen-demanding substances is a function of its physical and chemical characteristics above and below the dischar ge point. Various mathematical techniques, called models, have been developed to estimate this capacity. The Department follows the procedures as outlined in the “State/EPA Region IV Agreement on the Developm ent of Wasteload Allocations/Total Maximum Daily Loads and NPDES Permit Limitations” dated October 30, 1991 (as updated) for determining the assimilative capacity of a given water body. Mathematical mode ls such as QUAL2E and QUAL2E-UNCAS are used in accordance with “Enhanced Stream Water Quality Models QUAL2E and QUAL2E-UNCAS: Documentation and Users Manual” (EPA/600/3-87/007; dated May 1987) as updated. BOD 5 and UOD values determined from modeling results will be used in permitting as monthly average derived limits (C wla ). Daily maximum derived limits will typically be determined by multiplying the monthly average value by two.

For facilities subject to effluent guidelines limita tions or other technology-based limitations, BOD 5 will also be evaluated in accordance with the applicable industr ial categorical guidelines. These parameters will be identified in Part III of this rationale wh en they are applicable to the permit.

### Rationale Page 4 of 44 Permit No. SC0001333

b. Total Ammonia Nitrogen (as N):

Ammonia limitations based on oxygen demand will be de termined from modeling information as described above. These values will be used as monthly average de rived limits and a daily maximum will typically be determined by multiplying the monthly average derived limit by two. These values will be compared with the ammonia water quality criteria for protection of aqua tic life from Regulation 61-68, Attachment 3 and any categorical limitations. The more stringent of the limita tions will be imposed. Calculations for aquatic life criteria and other wasteload recommendations will be shown later in Part III of this rationale when ammonia is a pollutant of concern.

c. Discharges of Nutrients:

In order to protect and maintain lakes and other waters of the State, consideration is given to the control of nutrients reaching the waters of the State. Th erefore, in accordance with regulation R.61-68.E.9 , the Department controls the nutrients as prescribed below. Nutrient limitations will be determined from the best available information and/or modeling performed by the Wasteload Allocation Section to meet these water quality standards.

i. Discharges of nutrients from all sources, including point and nonpoint, to waters of the State shall be prohibited or limited if the discharge would result in or if the waters experience growths of microscopic or macroscopic vegetation such that the water quality standards would be violated or the existing or classified uses of the waters would be impaired. Load ing of nutrients shall be addressed on an individual basis as necessary to ensure compliance with the narrative and numeric criteria.

ii. Numeric nutrient criteria for lakes are based on an ecoregional approach which takes into account the geographic location of the lakes within the State and are listed below. These numeric criteria are applicable to lakes of 40 acres or more. Lakes of l ess than 40 acres will continue to be protected by the narrative criteria.

1. for the Blue Ridge Mountains ecoregion of the State, total phosphorus shall not exceed 0.02 mg/l, chlorophyll a shall not exceed 10 ug/l, and total nitrogen shall not exceed 0.35 mg/l

2. for the Piedmont and Southeastern Plains ecoregions of the State, total phosphorus shall not exceed 0.06 mg/l, chlorophyll a shall not exceed 40 ug/l, and total nitrogen shall not exceed 1.50 mg/l

3. for the Middle Atlantic Coastal Plains ecoregion of the State, total phosphorus shall not exceed 0.09 mg/l, chlorophyll a shall not exceed 40 ug/l, and total nitrogen shall not exceed 1.50 mg/l.

iii. In evaluating the effects of nutrients upon the qua lity of lakes and other waters of the State, the Department may consider, but not be limited to, such factors as the hydrology and morphometry of the waterbody, the existing and projected trophic state, characteristics of the loadings, and other control mechanisms in order to protect the ex isting and classified uses of the waters.

iv. The Department shall take appropriate action, to include, but not limited to: es tablishing numeric effluent limitations in permits, establishing Total Maximum Daily Loads, establishing waste load allocations, and establishing load allocations for nutrients to ensure th at the lakes attain and maintain the above narrative and numeric criteria and other app licable water quality standards.

v. The criteria specific to lakes sha ll be applicable to all portions of the lake. For this purpose, the Department shall define the applicable area to be th at area covered when measured at full pool elevation.

### Rationale Page 5 of 44 Permit No. SC0001333

2. Effluent concentration limits (C efflim ) for parameters other than th e parameters listed inG.1.aabove are established using the following procedures:

Q 7Q10 7Q10 or other critical flow condition of the receiving water at the discharge point in mgd. (may require adjustment for withdrawals) AAF d Average Annual Flow (AAF) or other critical flow condition of the receiving water at the discharge point in mgd. (may require adjustment for withdrawals) Q 7Q10i 7Q10 or other critical flow condition of the receiving water at the SWP Area boundary in mgd. AAF i Average Annual Flow (AAF) of the receiving water at the SWP Area boundary in mgd. Q d Long term average discharge flow in mgd.

a. Determine dilution factors: The following information is to be used (where a pplicable) for establishing effl uent concentration limits:

DF 1 : Dilution factor based on 7Q10 or other critical flow condition of the receiving water at the discharge point ( Q 7Q10 ). This dilution factor is used to determine the derived limits for protection of the following aquatic life and human hea lth concerns for the reasons indicated:

i. Aquatic Life (see R.61-68.C.4.a(1)). Prot ection of aquatic life on a short-term basis is needed at the point where aquatic orga nisms become exposed to the discharge.

ii. Human Health – Organism Consumption fo r parameters identified as non-carcinogens per R.61-68.C.4.b(1). Protection for human health on a short-term basis for consumption of aquatic organisms is needed at the point th e aquatic organisms become exposed to the discharge.



### Q Q d 

### ⎛ ⎞ ⎟ ⎟ + 7 Q 10 

### ⎜ ⎜ ⎝ = DF 1 

### Q d 

### ⎠

DF 2 : Dilution factor, at the discharge point, based on the Average Annual Flow of the receiving water at the discharge point ( AAF d ). This dilution factor is used to determine the derived limits for protection of the following human health and or ganoleptic concerns for the reasons indicated:

i. Human Health – Organism Consumption fo r parameters identified as carcinogens per R.61- 68.C.4.b(1). Protection for human health on a long-term basis to prevent cancer due to consumption of aquatic organisms is needed at the point the aquatic organisms become exposed to the discharge where it enters the receiving water.

ii. Organoleptic effects per R.61-68.C.4.b(1). Pr otection for taste and odor issues related to the discharge is needed at the point where th e discharge enters the receiving water. 

### ⎛ ⎞ ⎟ ⎟ AAF d 

### + Q d 

### ⎜ ⎜ ⎝ = DF 2 

### Q d 

### ⎠

DF 3 : Dilution factor based on the 7Q10 or other criti cal flow condition at the source water protection area boundary for protection of a proposed or exis ting water intake downstream of the discharge ( Q 7Q10i ). This dilution factor is used to determine the derived limits for protection of the following human health concerns for the reasons indicated:

### Rationale Page 6 of 44 Permit No. SC0001333

i. Human Health – Water and Organism C onsumption for parameters identified as noncarcinogens per R.61-68.C.4.b(1) and E.12.c(5) to protect for short-term health effects when the discharge is above any drinking water inta ke. Protection of human health relative to drinking the water from the waterbody and consuming aquatic organisms from the same waterbody is provided by this criterion, but drinking the water withdrawn from the waterbody may require a potentially higher level of protection in terms of applicable dilution than consumption of organisms. In addition, to satisfy the requirements of R.61-68.C.10(a), the Department has determined that dilution at the boundary of the Source Water Protection area will protect the drinking water intake to meet this requirement.

For discharges affecting the primary SWP area, dilution will be determined using the largest TOT 10 flow along the SWP area boundary upstream of the drinking water intake of concern. If multiple drinking water intakes are present below the discharge, the SWP area of the intake closest to the discharge will be protect ed. If the entire basin is designated as the SWP area, the boundary will be the TOT 10 at the beginning of the basin, even if it is outside the State boundaries (e.g. North Carolina).

ii. Human Health - Drinking Water Maximum Contaminant Level (MCL) for parameters identified as non-carcinogens per R.61-68.C.4.b(1) and E.12.c(5) to protect for short-term health effects when the discharge is above an y drinking water intake. Protection of human health relative to drinking the water from th e waterbody after conventional treatment per R.61-68.G.8 and 10 is provided by this criterion. In addition, to satisfy the requirements of R.61-68.C.10(a), the Department has determined that dilution at the boundary of the Source Water Protection area will protect the drinking wa ter intake to meet this requirement.

For discharges affecting the primary SWP area, dilution will be determined using the largest TOT 10 flow along the SWP area boundary upstream of the drinking water intake of concern. If multiple drinking water intakes are present below the discharge, the SWP area of the intake closest to the discharge will be protect ed. If the entire basin is designated as the SWP area, the boundary will be the TOT 10 at the beginning of the basin, even if it is outside the State boundaries (e.g. North Carolina).



### Q Q d 

### ⎛ ⎞ ⎟ ⎟ + 7 Q 10 i 

### ⎜ ⎜ ⎝ = DF 3 

### Q d 

### ⎠

DF 4 : Dilution factor based on the Average Annual Flow at the source water protection area boundary for protection of a proposed or existing wa ter intake downstream of the discharge ( AAF i ) This dilution factor is used to determine the derived limits for protection of the following human health concerns for the reasons indicated:

i. Human Health–Water and Organism Consum ption for parameters identified as carcinogens per R.61-68.C.4.b(1) and E.12.c(5) to protect for long-term health effects due to cancer when the discharge is above any drinking water inta ke. Protection of human health relative to drinking the water from the waterbody and consuming aquatic organisms from the same waterbody is provided by this criterion, but drinking the water withdrawn from the waterbody may require a potentially higher level of protection in terms of applicable dilution than consumption of organisms. In addition, to satisfy the requirements of R.61-68.C.10(a), the Department has determined that dilution at the boundary of the Source Water Protection area will protect the drinking water intake to meet this requirement.

### Rationale Page 7 of 44 Permit No. SC0001333

For discharges affecting the primary SWP area, dilution will be determined using the largest TOT 10 flow along the SWP area boundary upstream of the drinking water intake of concern. If multiple drinking water intakes are present below the discharge, the SWP area of the intake closest to the discharge will be protect ed. If the entire basin is designated as the SWP area, the boundary will be the TOT 10 at the beginning of the basin, even if it is outside the State boundaries (e.g. North Carolina).

ii. Human Health - Drinking Water Maximum Contaminant Level (MCL) for parameters identified as carcinogens per R.61-68.C.4.b(1) and E.12.c(5) to protect for long-term health effects due to cancer when the discharge is a bove any drinking water intake. Protection of human health relative to drinking the wate r from the waterbody and consuming aquatic organisms from the same waterbody is provided by this criterion, but drinking the water withdrawn from the waterbody may require a pot entially higher level of protection in terms of applicable dilution than consumption of organisms. In addition, to satisfy the requirements of R.61-68.C.10(a), the Department has determined that dilution at the boundary of the Source Water Protection area will protect the drinking water intake to meet this requirement.

For discharges affecting the primary SWP area, dilution will be determined using the largest TOT 10 flow along the SWP area boundary upstream of the drinking water intake of concern. If multiple drinking water intakes are present below the discharge, the SWP area of the intake closest to the discharge will be protect ed. If the entire basin is designated as the SWP area, the boundary will be the TOT 10 at the beginning of the basin, even if it is outside the State boundaries (e.g. North Carolina). 

### ⎛ AAF i 

### + Q d 

### ⎞ ⎟ ⎟ DF 4 

### ⎜ ⎜ ⎝ = Q d 

### ⎠

b. Determine monthly average derived limits using the following procedures:

WQS al Freshwater Standard (based on an established cr iteria or other published data per R.61-68) for protection of Aquatic Life; may be a CCC or CMC as defined below WQS org Standard (based on an established criteria or ot her published data per R.61-68), for protection of Human Health – Organism Consumption WQS wo Standard (based on an established criteria or ot her published data per R.61-68), for protection of Human Health – Water & Organism Consumption. Applicable only if any portion of the mixing zone for this discharge is in a state-approve d source water protection area for a proposed or existing water intake downstream of the wastewater treatment plant discharge point. WQS mcl Standard (based on an established criteria or other published data per R.61-68), for Drinking Water MCL (Maximum Contaminant Level). Applicable only if any portion of the mixing zone for this discharge is in a state-approved sour ce water protection area for a proposed or existing water intake downstream of the wastewater treatment plant discharge point. WQS ol : Standard (based on an established criteria or other published data per R.61-68), based on Organoleptic Data. C aqlife Concentration limit derived from aquatic life data C

HH Concentration limit derived from human hea lth data as determined from organism ( C org ), water/organism ( C wo )and MCL ( C mcl ) data C

ol Concentration limit derived from organoleptic data

### Rationale Page 8 of 44 Permit No. SC0001333

C

b Background concentration of the concerned pa rameter in mg/l determined from ambient monitoring data or data provided by applicant. The 90 th percentile of ambient monitoring data for aquatic life protection for the parameters identified in the Appendix (Water Quality Numeric Criteria) to Regulation 61-68 from the last 3 years, or whatever is available if less than 3 years, will typically be used per the procedures used for 303(d) listing. The median value of ambient monitoring data for human health protection for th e parameters identified in the Appendix (Water Quality Numeric Criteria) to Regulation 61-68 from the last 3 years, or whatever is available if less than 3 years, will typically be used pe r the procedures used for 303(d) listing. The background concentration is assumed to be zero (0) in the absence of actual data based on Departmental guidance and EPA recommendation.

i. Determine the derived limit for protection of Aquatic Life ( C aqlife )

1. The following guidelines apply to determining aquatic life limits:

a. Typically, the Criterion Maximum Concentration (CMC) is applied as a daily maximum derived limit and the Criterion Continuous Con centration (CCC) is applied as a monthly average derived limit, after consideration of dilution and background concentrations. Exceptions exist based on EPA criteria and are indicated for specific parameters. The CMC and CCC for specific metals will be adjusted using the procedures in 60 FR 22229, “Water Quality Standards; Establishment of Numeric Cr iteria for Priority Toxic Pollutants; States’ Compliance-Revision of Metals Criteria,” May 4, 1995 and the “Technical Guidance on Interpretation and Implementation of Aquatic Life Metals Crite ria,” Oct. 1, 1993 and applied as a daily maximum and monthly average, respectively, after consideration of dilution and background concentrations.

b. If only a CMC exists for a particular para meter, a daily maximum derived permit limit only (no monthly average) will be set using that value, after consideration of dilution and background concentrations. If only a CCC is given, it will be used as a monthly average derived limit and the daily maximum derived limit will be two (2) times the value obtained for the monthly average based on a simplified statistical procedure for determining permit limits recommended in Section 5.4.2 of the US EPA’s “Technical Support Document for Water Quality-based Toxics Control”, EPA/505/2-90-001, March 1991 (hereafter known as the TSD) considering an assumed coefficient of variation (CV) of 0.6 and 95 th percentile occurrence probability.

c. If only an acute toxicity effect concentration for a number of species for a particular pollutant is given as a LC 50 , the lowest concentration should be divided by an acute-tochronic ratio (ACR) of 10 and a sensitivity factor of 3.3, for an acceptable instream concentration in order to protect against ch ronic toxicity effects (from R.61-68.E.14.a(1)). Other acute toxicity data will be handled sim ilarly. The value obtained from this calculation will be used as a monthly average derived limit after consideration of dilution and background concentrations. The daily maximum will be two (2) times the value obtained for the monthly average based on a simplified statistical procedure for determining permit limits recommended in Section 5.4.2 of the TSD considering an assumed coefficient of variation (CV) of 0.6 and 95 th percentile occurrence probability.

### Rationale Page 9 of 44 Permit No. SC0001333

d. If a chronic toxicity effect concentration for a number of species for a particular pollutant is given as a no observed effect concentration (NOEC), the lowest concentration should be divided by a sensitivity factor of 3.3 in order to protect against chronic toxicity to the most sensitive species (from R.61-68.E.14.a(2)). Other chronic toxicity data will be handled similarly. The value obtained from this calculati on will be used as a monthly average derived limit after consideration of dilution and b ackground concentrations. The daily maximum will be two (2) times the value obtained for the monthly average based on a simplified statistical procedure for determining permit lim its recommended in Section 5.4.2 of the TSD considering an assumed coefficient of variation (CV) of 0.6 and 95 th percentile occurrence probability.

e. If both acute and chronic data are available for a particular pollutant, monthly average derived limit will be calculated as in c and d above for each acute and chronic, respectively. The more stringent of the monthly average derived limits will be the monthly average derived limit used after consideration of dilu tion and background concentrations. The daily maximum will be two (2) times the value obtained for the monthly average based on a simplified statistical procedure for determin ing permit limits recommended in Section 5.4.2 of the TSD considering an assumed coeffi cient of variation (CV) of 0.6 and 95 th percentile occurrence probability.

2. Consider the background concentration ( C b ) of the parameter of concern. If the background concentration is equal to or greater than the applicable standard ( WQS, as defined above) for the parameter of concern, then the derived concentration limit ( C aqlife ) for that parameter and for the protection of that standard, is established equal to the standard ( WQS ). An exception exists where the naturally occurring instream concentra tion for a substance is higher than the derived permit effluent limitation. In those situations , the Department may establish permit effluent limitations ( C efflim ) at a level higher than the derived limit, but no higher than the natural background concentration. In such cases, the Department may require biological instream monitoring and/or whole effluent toxicity (WET) testing (See R.61-68.E.12.c.2). i.e.

If C b is not based on naturally occurring concentrations and



### C b 

### ≥ WQS

Then



### C

aqlife 

### = WQS

.

If C b is based on naturally occurring concentrations and



### C b 

### ≥ WQS

Then



### C aqlife 

### < C eff lim 

# ≤ C b .

Otherwise, the limits are established as described in Item 3 or 4 below.

### Rationale Page 10 of 44 Permit No. SC0001333

3. For the parameters listed in Table A below, Regulation R.61-68 Section E.12 provides for the use of the EPA Office of Water Policy and "Technical Guidance on Interpretation and Implementation of Aquatic Life Metals Criteri a", October 1, 1993. A subsequent revision published in the Federal Register (60 FR 22229) on May 4, 1995 updated the data in the original report. See R.61-68 Attachment 1 “Conversion Factors for Dissolved Metals” and Attachment 2 “Parameter for Calculating Freshwater Dissolved Metals Criteria that are Hardness-Dependent”. The following equations and constants will be used to calculate aquatic life metals limits based on the Federal Register data. The water quality standard for these metals (CCC or CMC) will also be adjusted using this approach in accordance with Regulation 61-68.E.12.d(3) for evaluation of ambient water quality.

TSS e Effluent Total Suspended Solids (TSS) c oncentration in mg/l from actual or proposed monthly average permit limits. TSS b Background or in-stream Total Suspended Solids (TSS) concentration. The background TSS is assumed to be 1 mg/l in the absence of actual instream data based on the 5th percentile of ambient TSS data on South Carolina waterbodies from 1993-2000. TSS avg Average in-stream (mixed) TSS concentration. CF Conversion factor considered most relevant in fresh water for aquatic life as defined by EPA in dissolved metals documents for each listed metal H Hardness in mg/l of CaCO 3 . Per R.61-68.E.12.a(3), the CMC and CCC are based on a hardness of 25 mg/l if the ambient hardness is less than 25 mg/l. Concentrations of hardness less than 400 mg/l may be based on the actual mixed stream hardness if it is greater than 25 mg/l and less than 400 mg/l and 400 mg/l if the ambient hardness is greater than 400 mg/l. The background hardness is assumed to be 25 mg/l in the absence of actual stream data. Mixed stream ha rdness may be determined using effluent hardness and actual stream hardness. K

po Metal-specific equilibrium constant

a Metal-specific constant K

p Linear partition coefficient K

pb Linear partition coefficient for use in the deri vation of an adjusted water quality standard C

d Dissolved phase metal concentration C t Total metal concentration S a constant to represent the CCC or CMC

The following table lists the values for the c onstants, the CCC and CMC, and the recommended values of the conversion factors (CF).

Table A Parameter k po a CMC CF CMC CCC CF CCC (μg/l) (μg/l) Arsenic 0.48 x 10 6 -0.7286 340 100 150 100 Cadmium 4.00 x 10 6 -1.1307 0.95* 100* 0.83* 96.7* Chromium+3 3.36 x 10 6 -0.9304 580* 31.6 28* 86 Chromium+6 3.36 x 10 6 -0.9304 16 98.2 11 96.2 Copper 1.04 x 10 6 -0.7436 3.8* 96 2.9* 96 Lead 0.31 x 10 6 -0.1856 14* 99.3* 0.54* 99.3* Mercury 2.91 x 10 6 -1.1356 1.6 85 0.91 85 Nickel 0.49 x 10 6 -0.5719 150* 99.8 16* 99.7 Zinc 1.25 x 10 6 -0.7038 37* 97.8 37* 98.6

### Rationale Page 11 of 44 Permit No. SC0001333

* The equations for calculating the CCC, CMC, a nd conversion factors are given in the Appendix to Regulation 61-68 and Attachments 1and 2 for each parameter. The values given for the CMC and CCC and CF in the table are based on 25 milligrams/liter (mg/l) hardness (as expressed as CaCO 3 ).

From Technical Guidance Manual for Performing Wast e Load Allocations Book II, Rivers and Streams , EPA/440/484/022:



### S = CMC or CCC

C d 

### = S × CF

To determine the adjusted water quality standard ( WQS al ), use S and the equation for C d above and the following equations:



### K = K a 

### ( 

### TSS ) b 

### × p b po 

# )

− 

### 1 K 10 6 

# }

To determine the effluent limit ( C aqlife ) , use S and the equation for C d above and the following equations: 

# { ( + WQS C TSS × × × = al d pb b



# ( Q Q × TSS b 

# ) Q TSS ( ) × + d 7 Q 10 e 

### TSS avg 

### = Q d 

### + 7 Q 10



### K K a 

### ( TSS avg 

### ) × = p po 

# )

− 

# { 1 10 6 

# }

Once C t has been calculated, it is multiplied by DF 1 and background concentrations are accounted for to obtain the monthly average derived limit ( C aqlife ): 

# ( K p 

### C C TSS × + × × = d t avg



### ⎪ ⎨ ⎧ C ⎪ ⎬ ⎫ Q 7 Q 10 

### ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ C aqlife 

### = ( C t 

### × DF 1 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

4. For all other parameters not included in paragraph 3, Table A, monthly average derived limits ( C aqlife ) for aquatic life protection are calculated as follows: 

### ⎪ ⎨ ⎧ C ⎪ ⎬ ⎫ Q 7 Q 10 

### ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ C

aqlife 

### = ( DF 1 

### × WQS al 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

ii. Determine derived limit for protection of Human Health

1. The following guidelines apply to determining human health limits:

### Rationale Page 12 of 44 Permit No. SC0001333

a. The human health criterion given by Regula tion 61-68 will be applied as a monthly average derived limit after consideration of d ilution and background concentrations ( C HH-avg ). Exceptions exist based on EPA criteria and are i ndicated for specific parameters. No limits on human health based on water and organism consumption or drinking water MCLs will be imposed if there is no potential to affect a dr inking water intake or source water protection area (i.e., if there is no intake downstream of the discharge).

b. The daily maximum permit limit will be determined from the monthly average value from (a) above and a multiplier ( M) determined using a statistical procedure recommended in Section 5.5 using average = 95 th percentile from Table 5-3 in the TSD. The permitted or proposed number of samples per month (n) is used with the coefficient of variation (CV) to determine M

. CV is assumed to be 0.6 as a defau lt value if information is not known.

( Z σ

− 5. 0 σ 2 )

m 

### M = e
( Z a σ n − 5. 0 σ 2 ) n 

### e

where:

2 

### ⎞



### σ 2


### = 

### ln ⎜ ⎜ ⎛ CV + 

### 1 ⎟ ⎟

n



### σ ⎝ n ⎠

2 2



### = ln 

# ( CV + 1 

# )

Std

. Deviation CV = coefficient of variation of the effluent concentration = 

### Mean

n = the number of effluent samples per month (where frequency is less than 1/month, n =1)

z m = the percentile exceedance probability for the daily maximum permit limit (=2.326 for 99 th percentile basis)

z a = the percentile exceedance probability for the monthly average permit limit (=1.645 for 95 th percentile basis)

C

HH-max = M * C HH-avg

2. Consider the background concentration ( C b ) of the parameter of concern. If the background concentration is equal to or greater than the applicable standard ( WQS, as defined above) for the parameter of concern, then the derived concentration limit ( C HHe ) for that parameter and for the protection of that standard, is established equal to the standard ( WQS ). An exception exists where the naturally occurring instream concentra tion for a substance is higher than the derived permit effluent limitation. In those situations , the Department may establish permit effluent limitations ( C efflim ) at a level higher than the derived limit, but no higher than the natural background concentration. In such cases, the Department may require biological instream monitoring and/or whole effluent toxicity (WET) testing (See R.61-68.E.12.c.3).

If C b is not based on naturally occurring concentrations and 

### C b 

### ≥ WQS
Then 

### C

HH 

### = WQS

. If C b is based on naturally occurring concentrations and 

### C b 

### ≥ 

### WQS

### Rationale Page 13 of 44 Permit No. SC0001333

Then 

### C HH 

### < C eff lim 

# ≤ C

. b

Otherwise, the limits are established as described in Items 3-6 below.

3. Human Health – Organism Consumption ( C org ).

a. For Carcinogens The Monthly Average is calculated as follows: 

### ⎪ ⎬ ⎫ 

### C ⎪ ⎨ ⎧ ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### AAF d 

### C

org 

### = 

### ( DF 2 

### × 

### WQS org 

### )

− × b 

### Q d 

### ⎪ ⎭ ⎪ ⎩ ⎝ ⎠

b. For Non-carcinogens The Monthly Average is calculated as follows:


### ⎪ ⎨ ⎧ 

### C ⎪ ⎬ ⎫ 

### Q 7 Q 10 

### ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### C

org 

### = 

### ( DF 1 

### × 

### WQS org 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

4. Human Health – Water and Organism Consumption ( C wo )

a. For Carcinogens The Monthly Average is calculated as follows: 

### ⎪ ⎨ ⎧ 

### C ⎪ ⎬ ⎫ ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### AAF i 

### C

wo 

### = 

### ( DF 4 

### × 

### WQS

wo 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

b. For Non-carcinogens The Monthly Average is calculated as follows: 

### ⎪ ⎨ ⎧ 

### C ⎪ ⎬ ⎫ 

### Q 7 Q 10 i 

### ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### C

wo 

### = 

### ( DF 3 

### × 

### WQS

wo 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

5. Human Health – Drinking Water Maximum Contaminant Level (MCL) ( C mcl ).

a. For Carcinogens The Monthly Average is calculated as follows:


### ⎪ ⎨ ⎧ 

### C ⎪ ⎬ ⎫ ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### AAF i 

### Q

d 

### C

mcl 

### = 

### ( DF 4 

### × 

### WQS mcl 

### )

− × b 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

b. For Non-carcinogens The Monthly Average is calculated as follows:


### ⎪ ⎨ ⎧ 

### C Q 7 Q 10 i 

### ⎪ ⎬ ⎫ ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### C

mcl 

### = 

### ( DF 3 

### × 

### WQS mcl 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

### Rationale Page 14 of 44 Permit No. SC0001333

6. Organoleptic criteria ( C ol ). The Monthly Average is calculated as follows:



### C ⎪ ⎨ ⎧ ⎪ ⎬ ⎫ ⎛ ⎜ ⎜ ⎞ ⎟ ⎟ 

### AAF d 

### C

ol 

### = 

### ( DF 2 

### × 

### WQS ol 

### )

− × b 

### Q d 

### ⎪ ⎩ ⎪ ⎭ ⎝ ⎠

c. Determine most stringent of applicable data us ing the monthly average derived limits determined or calculated above:

C

efflim = minimum of ( C aqlife , C org , C wo , C mcl , C ol, C wla )

Note: If a CMC is present for the parameter of c oncern, the daily maximum derived limit obtained from that calculation must also be considered under reasonable potential.

d. Determine whether the discharge causes, has the reasonable potential to cause or contributes to a water quality violation.

Regulation 61-9.122.44(d)(1)(i) states: “Limitations must control all pollutants or pollutant parameters (either conventional, nonconventional, or toxic polluta nts) which the Department determines are or may be discharged at a level which will cause, have the reasonable potential to cause, or contribute to an excursion above any State water quality standard, in cluding State narrative criteria for water quality.”

When determining whether a discharge causes, has th e reasonable potential to cause or contributes to an instream excursion, the Department will use proce dures which account for cont rols on point and nonpoint sources of pollution, the variability of the pollutant in th e effluent, the sensitivity of the species to toxicity testing (when evaluating whole effluent toxicity), and, where appropriate, the dilution of the effluent in the receiving water (R.61-9.122.44(d)(1)(ii)).

Based on the above statements, there are three scen arios when limitations are required, as follows:

i. When data provided by the permit applicant indicates values greater than the proposed limitation derived above, that discharge will cause an excursion above a narrative or numeric water quality criterion.

ii. A discharge will be determined to contribute to an excursion of a water quality criterion when the waterbody is impaired (e.g., on the 303(d) list) for the parameter of concern and that parameter is also being discharged at levels a bove the water quality criterion.

iii. Reasonable potential to cause a water quality violation is determined using the following information:

Chapter 3 of the TSD provides information for de termining the need for permit limits based on the regulatory statements above. A statistical proce dure is also presented in Chapter 3 for use in determining reasonable potential from effluent data. Other statistical methods may be used as well to evaluate data sets. “National Guidance for the Permitting, Monitoring, and Enforcement of Water Quality-Based Effluent Limitations Set Below Anal ytical Detection/Quantitation Level” draft dated March 22, 1994, offers recommendations on how to interpret data below detection capabilities to make a reasonable potential analysis.

All pollutants given in a wasteload allocation or an effluent limitation guideline will be limited in the permit.

### Rationale Page 15 of 44 Permit No. SC0001333

When effluent data consists of non-quantifiable/non-detectable valu es or when no effluent data is available, other factors and information are cons idered to determine reasonable potential. In situations where a pollutant is known to be present in the wastestream (due to production data or other information), we know it is being discharged and has the potential to impact even though it may not be quantifiable. The fact that it is present will be enough information to say reasonable potential exists for that pollutant. Therefore, a reasona ble potential decision is based on various data and information, and not just non-quantifiable/non-detect able data. Considerati on is given to existing data, dilution in the waterbody, type of receiving wa ter, designated use, type of industry/wastestream, ambient data, history of compliance, and history of toxic impact. If any source of information indicates reasonable potential to cause, or contribute to an exceedance of the water quality standard, a water quality limit will be developed.

Note: The result of the following calculations may indicate that reasonable potential does not exist. However, as stated above, oth er information may “override” this numerical determination to justify the need for a limit.

1. The procedure for determining reasonable potential from actual effluent data is explained in Box 3-2 on page 53 of the TSD. Multiplying factors are determined from Table 3-2 at a 95% confidence level and 95% probability in Section 3.3.2. The following describes the procedures used for determining reasonable potential for chemical-specific parameters and WET, under certain circumstances. More information on de termining reasonable potential for WET is given in Item 2 below.

Step 1: Data Analysis: The statistical calculations involved in the “Reasonable Potential” analysis require discrete numerical data. The following describes how the effluent data will be used in determining reasonable potential.

Actual analytical results should be used when ever possible. Results less than detection and quantification should be used as follows:

a. If the permittee reports results below the practical quantitation limit (PQL) (as defined by the permit), then the reported “less than PQL” value for a given sample is generally assumed to be zero.

b. If the permittee uses a detection/quantification level that is greater than the PQL, then the reported “less than” value for a given sample is generally assumed to be a discrete value equal to the detection/quantifi cation level used by the permittee.

c. If the reported data consists of both discrete and non-discrete values and/or the data is reported using varying detecti on/quantification levels, then, generally, a combination of the above two approaches is used, or the data is evaluated in a manner that is most appropriate for that data set.

Note: For information on the acceptable analytical methods and PQLs please refer to NPDES permit application attachment titled “Practical Quantitation Limits (PQL) and Approved Test Methods.”

### Rationale Page 16 of 44 Permit No. SC0001333

Step 2: Using data from the permit application, othe r data supplied by the applicant and/or Discharge Monitoring Report (DMR) data, determin e the total number of observations ( n ) for a particular set of effluent data and determine the highest value ( C max ) from that data set. For the monthly average comparison, the data se t will include monthly average results and n will be the number of months in which they sampled in the time period being evaluated. When there is also a daily maximum comparison, the data set will include daily maximum results and n will be the total number of samples in the time period being evaluated. Individual results may not necessarily be used in the calculation.
Step 3: Determine the coefficient of variation ( CV ) for the data set. For a data set where n >10, the CV is calculated as standard deviation divided by mean for the data set being evaluated. For data set where n <10, the CV is estimated to equal 0.6. For less than 10 items of data, the uncertainty in the CV is too large to calculate a standard deviation or mean with sufficient confidence.



### CV = 6.0 for 

### n < 10



### σ 

### CV = for 

### n > 10 

### μ

where: 

### σ = Standard Deviation of the samples 

### μ = Mean of the samples

Step 4: Determine the appropriate multiplying factor ( MF ) from either Table 3-2 or using the formulae in Section 3.3.2 of the TSD.

a. Determine the percentile represented by th e highest concentration in the sample data.

1/ n 

### p = 

### (1

− 

### Level Confidence 

### )

n where: p n = Percentile represented by the highest concentration in the data

n = number of samples Confidence Level = 0.95 i.e. 95%

b. Determine the multiplying factor ( MF ), which is the relationship between the percentile described above ( C p ) and the selected upper bound of the lognormal effluent distribution, which in this case will be the 95 th percentile ( C 95 ).



### MF = 

### C 95 

### = 

### e ( Z 95 σ + 5.0 σ 2 )

( Z p σ + 5.0 σ 2 ) 

### C p 

### e
where: Z 95 is the standardized Z-score for the 95 th percentile of the standardized normal distribution = 1.645

Z

p is the standardized Z-score for the p th percentile of the standardized normal distribution.(determined in (b) above)

Note: The values of Z-scores are listed in tabl es for the normal distribution. If using Microsoft® Excel, this can be calculated using the NORMSINV function.

2 2 

### σ = 

### ln( CV + 

### 1)

σ = ln( CV 2 

### + 1)

### Rationale Page 17 of 44 Permit No. SC0001333

Step 5: Multiply the highest value from the data set ( C max ) by the multiplying factor ( MF ) determined in Step 4 to obtain the maximum receiving water concentration ( RWC ).



### RWC = C × MF
max Step 6: RWC ≤ Derived monthly average limit ( C efflim ) implies that a reasonable potential does not exist.

RWC > Derived monthly average limit ( C efflim ) implies that a reasonable potential exists.

Note: If a CMC is available for a given parameter, the daily maximum value will be used in addition to the monthly average for a determination of reasonable potential.

2. Reasonable potential for WET will be determined from numerical data using one of the following procedures:

a. When the effluent data is given as LC 50 and/or NOEC values:
Step 1: Convert the given LC 50 and NOEC values to toxic units, TU a for acute data and TU c for chronic data, respectively, using the following formulae:



### 100 TU = a 

### LC 50


### 100 TU 

### = c 

### NOEC Step 2: Using DMR data or other data provided by the applicant, determine the total number of observations ( n ) for a particular set of effluent data and determine the highest value ( TU a ,

max or TU c , max ) from that data set.

Step 3: Determine the coefficient of variation ( CV ) for the data set. For a data set where n >10, the CV is calculated as standard deviation di vided by mean. For data set where n <10, the CV is estimated to equal 0.6. For less than 10 items of data, the uncertainty in the CV is too large to calculate a standard devi ation or mean with sufficient confidence.

Step 4: Determine the appropriate multiplying factor ( MF ) from either Table 3-2 or using the formulae in Section 3.3.2. (see iii.1, Step 4 above).

Step 5: Multiply the highest value of TU a , max or TU c , max from the data set by the multiplying factor ( MF ) determined in Step 4 and the dilution at the edge of the mixing zone (the test concentration obtained from mixing zone modeling or demonstration) to obtain the maximum receiving water concentration ( RWC )

RWC for Acute Toxicity = [ TU a , max * MF * conc. at MZ boundary] RWC for Chronic Toxicity = [ TU c , max * MF * conc. at MZ boundary ]

Step 6: RWC for Acute Toxicity ≤ 0.3TU a implies that a reasonable potential does not exist RWC for Acute Toxicity > 0.3TU a implies that a reasonable potential exists

RWC for Chronic Toxicity ≤ 1.0TU c implies that a reasonable potential does not exist RWC for Chronic Toxicity > 1.0TU c implies that a reasonable potential exists

### Rationale Page 18 of 44 Permit No. SC0001333

b. When pass/fail effluent data only is availabl e and all tests have passed, the Department may be able to determine reasonable potential in a manner similar to Item 1 above assuming the test concentration of interest is greater than or equal to the concentration at which the permittee has tested. If the permittee has not test ed at or above the test concentration of interest, the Department cannot say that reas onable potential does not exist, unless perhaps, circumstances related to the discharge have changed. If any failures exist in the data set that cannot be removed, reasonable potential may be determined to exist.

c. Where WET results are given as percent effect, the procedures in Item 1, Steps 1-6 above are followed. In the case of WET in these circumstances, C lim will be 25% for the monthly average and 40% for the maximum since these are the limits for WET testing as a percent effect preferred by the Department.

e. Determine permit limits based on water quality data

i. When the discharge is determined to cause or have the reasonable potential to cause a water quality violation for a particular parameter, except WET, lim its are needed. Limits are typically based on the monthly average values calculated from G.2.c above. However, daily maximum values may be evaluated under reasonable potential under certain ci rcumstances. If reasonable potential exists for either average or maximum derived limits, limits on both are needed per Regulation 61-9.122.45(d).

1. If the monthly average from G.2.c is based on a wasteload allocation for oxygen-demanding pollutants and nutrients and

a. no CMC exists, the water quality limits are monthly average = C wla daily maximum = 2 x C wla

b. a CMC exists (for ammonia), the water quality limits are monthly average = C wla
and the daily maximum is the most stringent of

daily maximum = 2 x C wla
or daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4 2. If the monthly average from G.2.c is based on a quatic life data given as a CCC, if the discharge causes, has the reasonable potential to cause or c ontributes to a water quality violation based on the monthly average and a CMC also exists fo r the parameter, the water quality limits are

monthly average = C aqlife-ma using CCC as WQS in G.2.b.i.3 or 4 daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4

3. If the monthly average from G.2.c is based on aquatic life data given as a CCC and if the discharge does not cause, have the reasonable pot ential to cause or contribute to a water quality violation for that monthly average, but a CMC al so exists for the parameter and the discharge causes, has the reasonable potential to cause or c ontributes to a water quality violation based on that daily maximum, the water quality limits are monthly average = C aqlife-ma using CCC as WQS in G.2.b.i.3 or 4 daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4

### Rationale Page 19 of 44 Permit No. SC0001333

4. If the monthly average from G.2.c is based on aquatic life data given as a CCC or other acute or chronic data and no CMC exists for the parameter, the water quality limits are

monthly average = C aqlife daily maximum = 2 x C aqlife

5. If no CMC exists and the monthly average from G. 2.c is based on human health (organism, w/o, MCL) data, the water quality limits are

monthly average = C HH daily maximum = M x C HH using the calculation for M from G.2.b.ii.1.b

6. If a CMC exists and the monthly average from G. 2.c is based on human health (organism, w/o, MCL) data, the water quality limits will be

monthly average = C HH
and the daily maximum will be the most stringent of

daily maximum = M x C HH using the calculation for M from G.2.b.ii.1.b

or daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4

7. If no CMC exists and the monthly average from G.2.c is based on organoleptic data, the water quality limits are

monthly average = C ol daily maximum = M x C ol using the calculation for M from G.2.b.ii.1.b

8. If a CMC exists and the monthly average from G.2.c is based on organoleptic data, the water quality limits will be

monthly average = C ol
and the daily maximum will be the most stringent of

daily maximum = M x C ol using the calculation for M from G.2.b.ii.1.b

or daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4

9. If only a CMC exists, then the water quality limits will be no monthly average and

daily maximum = C aqlife-dm using CMC as WQS in G.2.b.i.3 or 4

ii. If the discharge is determined to cause or ha ve the reasonable potential to cause a water quality violation for WET, permit limitations will be expl ained in the rationale for that parameter.

iii. If the discharge is determined to contribute to an existing water quality violation, monthly average and daily maximum limits will be set giving no cred it for dilution of the receiving water (end-of-pipe limits) based on the criteria in Item 1 above.

### Rationale Page 20 of 44 Permit No. SC0001333

f. Consider Effluent Limitations Guid elines (ELG or Categorical guidelines)

The more stringent of the effluent limitations gui delines average and maximum derived limits and water quality-derived average and maximum limits determined in e above shall be used as permit limits, unless other information indicates more stringent limits are needed as indicated in Section H at the end of this section. Categorical limitations based on mass may fi rst be converted to concentration using the long term average flow of the discharge for both the m onthly average and daily maximum calculations, unless the applicable guidelines require use of an alternate flow.

1. For Effluent guidelines based on production, limits will be calculated as follows:



### ELG lim 

### = 

# ∑ ( ELGprod )( ELG ) where

ELGlim: the mass limit, in lbs/day, for an a pplicable pollutant based on the production ELGprod: the production rate, in lbs, for the applicab le guideline(s), usually based on long term average data ELG: the effluent guideline limitation, given as a measure of production (e.g. lbs/1000 lbs), for an applicable pollutant

2. For Effluent guidelines based on flow, limits will be calculated as follows: 

## ( 34.8

ELGlim :the mass limit, in lbs/day, for an appli cable pollutant based on applicable flow ELGprod: the long term average flow rate, in MGD, for the applicable guideline(s) ELG: the concentration limitation, in mg/l, for an applicable pollutant from the applicable guideline(s)

a. For BOD and TSS limits based on OCPSF Effluent Guidelines with two or more applicable subparts in subparts B-H , the limits will be calculated as follows: 

### ELG lim 

### = 

# ∑ ( ELGflow )( ELG ) 

## ) where



### ⎛ ⎜ ⎜ production subpart ⎞ ⎟ ⎟ ELG O 

### = 

# ∑ ( ELG lim) where 

### production OCPSF total ⎝ ⎠

ELG o : the final OCPSF limitation, in lbs/day ELGlim: the limitation, in lbs/day, determined from the calculation in item 2 above.

H. Other considerations

1. When the derived permit effluent limitation based on aquatic life numeric criteria is below the practical quantitation limit for a substance, the derived perm it effluent limitation shall include an accompanying statement in the permit that the practical quantitati on limit using approved analytical methods shall be considered as being in compliance with the limit. A ppropriate biological monitoring requirements shall be incorporated into the permit to determine complian ce with appropriate water quality standards. (R.61- 68.E.12.c(2))

2. When the derived permit effluent limitation based on human health numeric criteria is below the practical quantitation limit for a substance, the derived permit effl uent limitation shall include an accompanying statement in the permit that the practical quantitation limit using approve d analytical methods shall be considered as being in compliance with the limit. (R.61-68.E.12.c(3))

### Rationale Page 21 of 44 Permit No. SC0001333

3. The effluent concentration limits determined above may not necessarily be the NPDES permit limit. NPDES Permit limits are determined after a reasonable potential analysis is conducted using these derived limits and also after evaluating other issues (e.g. anti-backsliding, antidegradation).

4. Mass limitations may be required in certain circumstan ces. When mass limits are calculated the formula to be used is as follows.

Mass (lb/day) = Flow (mgd) * Concentration (mg/l) * 8.34

5. Final Limitations will typically be rounded to two (2 ) significant figures (based on EPA’s policy with its national criteria) while considering the PQL for a given para meter. Rounding will be performed using the following procedure (as recommended by the DHEC lab):

a. If the digit of interest is even and the number following it is a five (5), the digit of interest remains the same.

b. If the digit of interest is odd and the number following it is a five (5), the digit of interest is rounded up.

c. If the digit of interest is even or odd and the numbe r following it is between 0 and 4, the digit of interest remains the same.

d. If the digit of interest is even or odd and the number following it is between 6 and 9, the digit of interest is rounded up.

### Rationale Page 22 of 44 Permit No. SC0001333

III. PERMIT LIMITATIONS AND MONITORING REQUIREMENTS

** NOTE: Although all DMR data since 1/1/00 has been reviewed for this permit reissuance, the permittee has indicated that the flow schematic they submitted is a best estimate of their exp ected flows during the next five years (the flow schematic is based on 2003 long term averages plus an expected increase in pr oduction). An anti-degradation/alternatives analysis has not been completed for this increase, therefore the permittee will be held to their existing discharge limits. This production increase will contribute and additional 0.038 mgd of process fl ow (this production falls under the same guidelines as their existing PET production). The final Outfall ( 001) discharges to the Congaree River. A ll internal outfalls combine at 001 before discharging to the river.

INTERNAL OUTFALL 01A Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04 Description of outfall and treatment: This outfall consists of stormwater (13% of the flow), non-contact cooling water (81% of the flow) and ancillary non-process water (6% of the flow). There is no treatment for this outfall.

Flow 1. Previous permit limits (effective 1/1/00 ) : Monthly average: MR mgd Daily Maximum: MR mgd Sampling Frequency: Daily Sample Type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest flow was reported on 4/30/02 as 2.271 mgd. 4. Actual long-term average flow (from 2003 flow schematic with anticipated future changes): 0.632 MGD 5. Conclusion: The permittee shall continue to m onitor and report flow at this internal outfall. Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Continuous

pH 1. Previous Permit Limits (effective 1/1/00 ) : MR standard units the maximum and minimum Sampling Frequency: Daily Sample type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest and lowest pH were reported on 3/ 31/02 as 8.3 standard units and 9/30/02 as 5.1 standard units. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Not applicable to this outfall. 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The permittee shall continue to MR the ma ximum and minimum pH (in standard units), however the monitoring frequency has been reduced to monthly based on the Department’s review of past DMR data. Sampling Frequency: 1/Month Sample type: Grab

Temperature 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: MR °F Daily Maximum: MR °F Sampling Frequency: Daily Sample type: Grab

### Rationale Page 23 of 44 Permit No. SC0001333

2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest temperature was reported on 7/31/02 as 94 °F. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: not applicable 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The permittee shall continue to MR temper ature, however the monitoring frequency has been reduced to monthly based on the Department’s review of past DMR data. Monthly average: MR °F Daily Maximum: MR °F Sampling Frequency: 1/Month Sample type: Grab

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Effluent limitations guidelines: The permittee indicated in an e-mail dated 7/26/04 that th eir non-contact cooling water is 81% of the flow at this outfall: (0.632 mgd x 0.81 = 0.5119 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 5 mg/l Daily Max: 10 mg/l Monthly average limit: 0.5119 mgd x 5 mg/l x 8.345 (lbs-L)/(MG-mg) = 21 lbs/day Daily maximum limit: 0.5119 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 43 lbs/day 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03 ) : Not applicable to this internal outfall. 7. Other information: None 8. Conclusion: Although a BOD 5 contribution has been determined for this outfall, BOD 5 does not need to be monitored at this outfall. A net BOD 5 limit is established at Outfall 001

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Water Quality Data: NA 5. Effluent limitations guidelines: The permittee indicated in an e-mail dated 7/26/04 that th eir non-contact cooling water is 81% of the flow at this outfall: (0.632 mgd x 0.81 = 0.5119 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 10 mg/l Daily Max: 20 mg/l Monthly average limit: 0.5119 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 43 lbs/day Daily maximum limit: 0.5119 mgd x 20 mg/l x 8.345 (lbs-L)/(MG-mg) = 85 lbs/day 6. Other information: None 7. PQL: 1000 μg/l 8. Conclusion: Although a TSS contribution has been determined for this outfall, this parameter does not need to be monitored at this outfall. A net TSS limit is established at Outfall 001.

### Rationale Page 24 of 44 Permit No. SC0001333

INTERNAL OUTFALL 01D Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04 Description of outfall and treatment: This outfa ll consists of stormwater (9.5% of the fl ow), water filtration effluent 2% of t he flow), non-contact cooling water (97% of the flow) and ancillary non-process water (0.5% of the flow). There is no treatment for this outfall.

Flow 1. Previous permit limits (effective 1/1/00 ) : Monthly average: MR mgd Daily Maximum: MR mgd Sampling Frequency: Daily Sample Type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest flow was reported on 7/31/02 as 50.971 mgd. 4. Actual long-term average flow (from 2003 flow schem atic with anticipated future changes): 25.586 mgd 5. Conclusion: The permittee shall continue to monitor and report flow at this internal outfall. Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Continuous
pH 1. Previous Permit Limits (effective 1/1/00 ) : MR standard units the maximum and minimum Sampling Frequency: Daily Sample type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest and lowest pH were reported 10/ 31/03 as 9.2 standard units and 10/31/01 as 6.8 standard units. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Not applicable to this discharge. 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The permittee shall continue to MR the ma ximum and minimum pH (in standard units), however the monitoring frequency has been reduced to monthly based on the Department’s review of past DMR data. Sampling Frequency: 1/Month Sample type: Grab
Temperature 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: MR °F Daily Maximum: MR °F Sampling Frequency: Daily Sample type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest temperature was reported on 7/31/03 as 101°F. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: not applicable 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The permittee shall continue to MR temperature. Monthly average: MR °F Daily Maximum: MR °F Sampling Frequency: Daily Sample type: Continuous

### Rationale Page 25 of 44 Permit No. SC0001333

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Effluent limitations guidelines: The permittee indicated in e-mails dated 5/6/04 & 7/26/04 that 97% of the flow at Outfall 01D is non-contact cooling water (25.586 mgd x 0.97 = 24.8184 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 5 mg/l Daily Max: 10 mg/l Monthly average limit: 24.8184 mgd x 5 mg/l x 8.345 (lbs-L)/(MG-mg) = 1036 lbs/day Daily maximum limit: 24.8184 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 2071 lbs/day 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03 ) : Not applicable to this internal outfall. 7. Other information: None 8. Conclusion: Although a BOD 5 contribution has been determined for this outfall, BOD 5 does not need to be monitored at this outfall. A net BOD 5 limit is established at Outfall 001.

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Water Quality Data: NA 5. Effluent Limitation Guidelines: The permittee indicated in e-mails dated 5/6/04 & 7/26/04 that 97% of the flow at Outfall 01D is non-contact cooling water (25.586 mgd x 0.97 = 24.8184 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 10 mg/l Daily Max: 20 mg/l Monthly average limit: 24.8184 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 2071 lbs/day Daily maximum limit: 24.8184 mgd x 20 mg/l x 8.345 (lbs-L)/(MG-mg) = 4142 lbs/day 6. Other information: None 7. PQL: 1000 μg/l 8. Conclusion: Although a TSS contribution has been determined for this outfall, this parameter does not need to be monitored at this outfall. A net TSS limit is established at Outfall 001.

INTERNAL OUTFALL 01E Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04

Description of outfall and treatment: This out fall consists of stormwater (0.1% of th e flow), non-contact cooling water (98.9% of the flow), contact cooling water (0.5% of the flow), de-i onized water treatment effluent (0.3% of the flow), groundwater withdrawal (<0.1% of the flow), cooling tower blowdown (0 .1% of the flow) and ancillary non-process water (0.1% of the flow). This discharge is from a cooling basin. The contact cooling water is not subject to categorical guidelines as it only comes in contact with molten polymer (inert) and is used to cool the polymer to a solid state. There are no pollutants of concern for the contact cooling water, other than temperature.

Flow 1. Previous permit limits (effective 1/1/00 ) : Monthly average: MR mgd Daily Maximum: MR mgd Sampling Frequency: Daily Sample Type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only.

### Rationale Page 26 of 44 Permit No. SC0001333

3. DMR Data: The highest flow was reported on 8/31/03 as 78.199 mgd. 4. Actual long-term average flow (from 2003 flow schem atic with anticipated future changes): 63.423 mgd 5. Conclusion: The permittee shall continue to monito r and report the flow at this internal outfall. Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Continuous

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : Monthly average: MR mg/l Daily maximum: MR mg/l Sampling frequency: 1/Month Sample type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest BOD 5 was reported on 4/30/02 as 7 mg/l. All other DMR data was below 5 mg/l with the majority reported as 0 mg/l. 4. Effluent limitations guidelines: The permittee indicated in e-mails dated 5/6/04 & 7/26/04 that 98.9% of the flow at Outfall 01E is non-contact cooling water and that 0.1% of the flow is cooling tower blowdown (63.423 mgd x 0.99 = 62.7888 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 5 mg/l Daily Max: 10 mg/l Monthly average limit: 62.7888 mgd x 5 mg/l x 8.345 (lbs-L)/(MG-mg) = 2620 lbs/day Daily maximum limit: 62.7888 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 5240 lbs/day 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03 ) : Not applicable to this internal outfall. 7. Other information: None 8. Conclusion: A net BOD 5 limit is established at Outfall 001, therefore ther e is no need for the permittee to continue to monitor BOD 5 at this outfall.

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Water Quality Data: NA 5. Effluent limitations guidelines: The permittee indicated in e-mails dated 5/6/04 % 7/26/04 that 98.9% of the flow at Outfall 01E is non-contact cooling water and that 0.1% of the flow is cooling tower blowdown (63.432 mgd x 0.99 = 62.7888 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 10 mg/l Daily Max: 20 mg/l Monthly average limit: 62.7888 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 5240 lbs/day Daily maximum limit: 62.7888 mgd x 20 mg/l x 8.345 (lbs-L)/(MG-mg) = 10479 lbs/day 6. Other information: None 7. PQL: 1000 μg/l 8. Conclusion: Although a TSS contribution has been determined for this outfall, this parameter does not need to be monitored at this outfall. A net TSS limit is established at Outfall 001.

### Rationale Page 27 of 44 Permit No. SC0001333

pH 1. Previous Permit Limits (effective 1/1/00 ) : 6.0-9.0 standard units. Sampling Frequency: Daily Sample type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest and lowest pH was reported on 7/ 31/02 as 10.1 standard units and 7/31/00 as 6 standard units. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Not applicable to this discharge. 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The pH limits shall be in accordance with the previous permit. Range: 6.0-9.0 standard units Sampling Frequency: Daily Sample type: Continuous Exceeding the limits for pH on this internal outfall is not cons idered a violation if the permittee can demonstrate that the excursion is due to natural biological activity of algae forma tion. Evidence of this must be submitted with the DMRs and must show the variance in day-to-night variation for pH and dissolved oxygen as well as the variance of pH from the influent and effluent in the Discharge Lagoon. In order for this condition to apply, th e influent pH shall not be less than 6.0 standard units nor greater than 9.0 standard units. *In accordance with 401.17, pH Effluent limitations unde r continuous monitoring are specified as follows. Where a permittee continuously measures the pH of wastewater pursuant to a requirement or option in a National Pollutant Discharge Elimination System (NPDES) pe rmit issued pursuant to section 402 of th e Act, the permittee shall maintain the pH of such wastewater within the range set forth in the a pplicable effluent limitations guidelines, except excursions from the range are permitted subject to the following limitations: (a) The total time during which the pH values are outside the required range of pH values shall not exceed 7 hours and 26 minutes in any calendar month; and (b) No individual excursion from the range of pH values shall exceed 60 minutes. For purposes of this section, an excursion is an unintenti onal and temporary incident in which the pH value of discharge wastewater exceeds th e range set forth in the applicable effl uent limitations guidelines. (Secs. 301, 304, 306 and 501 of the Clean Water Act (the Federal Water Pollu tion Control Act Amendments of 1972, 33 U.S.C. 1251 et. seq., as amended by the Clean Water Act of 1977, Pub. L. 95-217))
Temperature 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: 98°F Daily Maximum: 105°F Sampling Frequency: Daily Sample type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest temperature was reported on 7/31/02 as 93°F. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: not applicable 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The temperature limits shall be in accordance with the previous permit. Monthly average: 98°F Daily Maximum: 105 °F Sampling Frequency: Daily Sample type: Continuous

### Rationale Page 28 of 44 Permit No. SC0001333

Oil and grease 1. Previous Permit Limits (effective 1/1/00 ) : Daily Maximum: 5 mg/l Sample type: 1/Month Sampling Frequency: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest oil and grease value was reported on 1/31/04 as 9 mg/l. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Not applicable to this outfall. 6. Other information: Previous limit due to possible contact w ith oil & use of oil skimmer in the cooling water basin. 7. PQL: 5 mg/l 8. Conclusion: Oil and grease shall be limited in accordance with the pervious permit, as the 9 mg/l DMR data point demonstrates that reasonable potential exists to exceed the 5 mg/l limit. MR has been included for monthly average. Monthly average: MR mg/l Daily Maximum: 5 mg/l Sample type: Grab Sampling Frequency: 1/Month

INTERNAL OUTFALL 01F Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04 Description of outfall and treatment: This outfall consists of process and sanitary ww and stormwater. Voridian has a 3.0 mgd activated sludge plant with aerobic digestion. Sludge is dewate red and incinerated or land app lied onsite (during incinerator maintenance/failure only).

Note: This internal outfall is subject to the following effluent guidelines: 40CFR Part 414 Organic Chemicals, Plastics and Synthetic Fibers Subparts D (Thermoplastic Resins): 0.648 mgd– PET Production* F (Commodity Organic Chemicals): 0.8 mgd – Intermediates Production I (Direct Discharge Point Sources that use End-of-Pipe Biological Treatment) * The additional 0.038 mgd PET flow (for the producti on increase) is not shown when the categorical limits are calculated below, as the permittee did not ask for an increase. Voridian no longer has a process ww from specialty plastics manufacturing. Flow 1. Previous permit limits (effective 1/1/00 ) : Monthly average: MR mgd Daily Maximum: MR mgd Sampling Frequency: Daily Sample Type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest flow was reported on 3/31/03 as 2.388 mgd. 4. Actual long-term average flow (from 2003 flow schema tic with anticipated future changes): 1.727 mgd 5. Conclusion: The permittee shall continue to monitor and report flow at this internal outfall. Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Continuous

### Rationale Page 29 of 44 Permit No. SC0001333

Dissolved Oxygen (DO) 1. Previous Permit Limits (effective 1/1/00 ) : ∃ 1.0 mg/l at all times Sampling frequency: 1/Week Sample type: Grab 2. NPDES Application: not measured 3. DMR Data: The lowest DO was reported on 4/30/01 as 2 mg/l. 4. Water Quality Data: The DO water quality limitation will be assessed for Outfall 001, water quality standards are not applicable to this internal outfall. 5. PQL: Not applicable. 6. Waste Load Allocation dated ( 8/14/03) : No t applicable to this internal outfall. 7. Other information: None 8. Conclusion: The DO limitation shall be in accordance with the previous permit. 1.0 mg/l minimum at all times Sampling frequency: 1/Week Sample type: Grab

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : Monthly average: 311 #/d Daily maximum: 820 #/d Sampling frequency: 3/Week Sample type: 24 Hour Composite 2. NPDES Application ( 2C dated 3/26/04) : The 2C application reported paramete rs for Outfall 001 only. 3. DMR Data: The highest BOD 5 was reported on 11/30/00 as 704 #/d. 4. Effluent limitations guidelines & Professional Judgment:

a. Guidelines for 40CFR Part 414 Subpart D: Monthly average: 24 mg/l Daily maximum: 64 mg/l b. Guidelines for 40CFR Part 414 Subpart F: Monthly average: 30 mg/l Daily maximum: 80 mg/l

c. Sanitary WW: Secondary Treatment Regulations (R.61-9.133.102) Monthly average: 30 mg/l Daily maximum: 60 mg/l Calculations:

a. Part 414 Subpart D Flow: 0.648 mgd Monthly Average = 24 mg/l x 0.648 mgd x 8.345 (# L/mg MG) = 129.78 #/d Daily Maximum = 64 mg/l x 0.648 mgd x 8.345 (# L/mg MG) = 346.08 #/d b. Part 414 Subpart F Flow: 0.8 mgd Monthly Average = 30 mg/l x 0.8 mgd x 8.345 (# L/mg MG) = 200.28 #/d Daily Maximum = 80 mg/l x 0.8 mgd x 8.345 (# L/mg MG) = 534.08 #/d

c. Sanitary Flow: 0.052 mgd Monthly Average = 30 mg/l x 0.052 mgd x 8.345 (# L/mg MG) = 13 .02 #/d Daily Maximum = 60 mg/l x 0.052 mgd x 8.345 (# L/mg MG) = 26.04 #/d Total BOD 5 Contributions: Monthly Average = 129.78 #/d + 200.28 #/d + 13.02 #/d = 343 #/d Daily Maximum = 346.08 #/d + 534.08 #/d + 26.04 #/d = 906 #/d 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03) : No t applicable to this internal outfall. 7. Other information: PET and intermediates produc tion increased since the last permit reissuance.

### Rationale Page 30 of 44 Permit No. SC0001333

8. Conclusion: The BOD 5 limits are in accordance with the previous permit (they are more stringent than those calculated above). The monitoring frequency has been reduced to weekly due to their compliance history and to be consistent with other parameters at this outfall. The permittee shall also report the concentration values. Monthly average: 311 #/d, MR mg/l Daily maximum: 820 #/d, MR mg/l Sampling Frequency: 1/Week Sampling Type: 24 Hour Composite

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : Monthly average: 510 #/d Daily Maximum: 1605 #/d Sampling frequency: 3/Week Sample Type: 24 Hour Composite 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest TSS was reported on 12/31/03 as 1202 #/d. 4. Water Quality Data: NA 5. Effluent limitations guidelines & Professional Judgment:

a. Guidelines for 40CFR Part 414 Subpart D: Monthly average: 40 mg/l Daily maximum: 130 mg/l b. Guidelines for 40CFR Part 414 Subpart F: Monthly average: 46 mg/l Daily maximum: 149 mg/l

c. Sanitary WW: Secondary Treatment Regulations (R.61-9.133.102) Monthly average: 30 mg/l Daily maximum: 60 mg/l Calculations:

a. Part 414 Subpart D Flow: 0.648 mgd Monthly Average = 40 mg/l x 0.648 mgd x 8.345 (# L/mg MG) = 216.30 #/d Daily Maximum = 130 mg/l x 0.648 mgd x 8.345 (# L/mg MG) = 702.98 #/d b. Part 414 Subpart F Flow: 0.8 mgd Monthly Average = 46 mg/l x 0.8 mgd x 8.345 (# L/mg MG) = 307.10 #/d Daily Maximum = 149 mg/l x 0.8 mgd x 8.345 (# L/mg MG) = 994.72 #/d

c. Sanitary Flow: 0.052 mgd Monthly Average = 30 mg/l x 0.052 mgd x 8.345 (# L/mg MG) = 13 .02 #/d Daily Maximum = 60 mg/l x 0.052 mgd x 8.345 (# L/mg MG) = 26.04 #/d Total TSS Contributions: Monthly Average = 216.30 #/d + 307.10 #/d + 13.02 #/d = 536 #/d Daily Maximum = 702.98 #/d + 994.72 #/d + 26.04 #/d = 1724 #/d 6. Other information: PET and intermediates produc tion increased since the last permit reissuance. 7. PQL: 1 mg/l 8. Conclusion: The TSS limits are in accordance with the previous permit (they are more stringent than those calculated above). The monitoring frequency has been reduced to weekly due to their compliance history and to be consistent with other parameters at this outfall. The permittee shall also report the concentration values. Monthly average: 510 #/d, MR mg/l Daily maximum: 1605 #/d, MR mg/l Sampling Frequency: 1/Week Sample type: 24 Hour Composite

### Rationale Page 31 of 44 Permit No. SC0001333

pH 1. Previous Permit Limits (effective 1/1/00 ) : 6.0-9.0 standard units. Sampling Frequency: Daily Sample type: Continuous 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest and lowest pH was reported on 4/30/ 03 as 8.8 standard units and 8/31/02 as 6.4 standard units. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: 6.0-9.0 standard units 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The pH should remain between 6.0 and 9.0 standard units, as in the previous permit. Sampling Frequency: Daily Sample type: Continuous *In accordance with 401.17, pH Effluent limitations unde r continuous monitoring are specified as follows.

Where a permittee continuously measures the pH of wastewat er pursuant to a requirement or option in a National Pollutant Discharge Elimination System (NPDES) permit issu ed pursuant to section 402 of the Act, the permittee shall maintain the pH of such wastewater within the range set forth in the applicable effluent limitations guidelines, except excursions from the range are permitted subject to the following limitations:

(a) The total time during which the pH values are outside the required range of pH values shall not exceed 7 hours and 26 minutes in any calendar month; and

(b) No individual excursion from the range of pH values shall exceed 60 minutes.

For purposes of this section, an excursion is an unintenti onal and temporary incident in which the pH value of discharge wastewater exceeds th e range set forth in the applicable effl uent limitations guidelines. (Secs. 301, 304, 306 and 501 of the Clean Water Act (the Federal Water Pollu tion Control Act Amendments of 1972, 33 U.S.C. 1251 et. seq., as amended by the Clean Water Act of 1977, Pub. L. 95-217)) of 1972, 33 U.S.C. 1251 et. seq., as amended by the Clean Water Act of 1977, Pub. L. 95-217))

Oil and grease 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: 112 #/d Daily Maximum: 169 #/d Sampling frequency: 1/Week Sample Type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest oil and grease value was reported on10/31/03 as 118 mg/l 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines:

a. Standard Guidelines for Oil and Grease: Monthly average: 10 mg/l Daily maximum: 15 mg/l Calculations:

a. Process and Sanitary Flows: 1.5 mgd Monthly Average = 10 mg/l x 1.5 mgd x 8.345 (# L/mg MG) = 125.18 #/d = 125 #/d Daily Maximum = 15 mg/l x 1.5 mgd x 8.345 (# L/mg MG) = 187.76 #/d = 188 #/d 6. Other information: None 7. PQL: 5 mg/l

### Rationale Page 32 of 44 Permit No. SC0001333

8. Conclusion: Oil and grease will be limited in accordance with the previous permit; they have demonstrated they can meet their previous limits. The permittee shall also report the concentration values. Monthly average: 112 #/d, MR mg/l Daily Maximum: 169 #/d, MR mg/l Sample type: Grab Sampling Frequency: 1/Week

Fecal Coliform 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: 200/100 ml Daily maximum: 400/100 ml (no more than 10% of total samples during a 30 day period shall exceed 400/100 ml) Sample type: Grab Sampling Frequency: 1/Week 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest value was 1280/100 ml reported on 4/30/ 00 (the permittee started up their UV system this month; this was the only fecal violation). All other DMR data was below 230/100 ml. 4. Water Quality Data: Fecal coliform standards in Re gulation 61-68.G.10(e) for Class FW are not to exceed 200/100ml based on five consecutive samples in a 30 day period and no mo re than 10% of the samples in the 30 day period shall exceed 400/100ml . 5. Effluent limitation guidelines: not applicable 6. Wasteload Allocation dated ( 8/14/03 ) : Not applicable to this internal outfall. 7. Other information: Although Station C-074 is impaired for fecal coliform, the permittee samples weekly and has had only one violation during the previous permit duration. If the permitt ee meets fecal coliform standards at this outfall, limits are not needed on Outfall 001, this is the only outfall with sanitary contributions. 8. PQL: 1/100 ml (Standard Method 9221C, 9221 E or 9221 D) 9. Conclusion: Fecal coliform, per R.61-68.E.12(c)(9), will be limited to Monthly average: 200/100 ml Daily maximum: 400/100 ml (no more than 10% of to tal samples during a 30 day period shall exceed 400/100 ml) Sample type: Grab Sampling Frequency: 1/Week

OCPSF: All OCPSF parameters listed under 40 CFR Part 414 Subpart I fo r end of pipe biological treatment will be evaluated. The effluent guideline values will be compared to the governi ng water quality criterion to obtain the more stringent limit. A monitoring waiver has not been requested for any of the parameters so all parameters will be limited with a sample frequency of once per year. The mass limits are calculated using the process flow and the concentrati on limits are based on the guidelin e value for that parameter. See Appendix B for OCPSF limits for this outfall. OCPSF flow is 0.8 + 0.648 mgd = 1.448 mgd.

INTERNAL OUTFALL 01G Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04

Description of outfall and treatment: This outfall consists of stormwater (11% ), non-contact cooling water (85%) and ancillary non-process water (4%). This di scharge is from an ash settling basin.

Flow 1. Previous permit limits (effective 1/1/00 ) : Monthly average: MR mgd Daily Maximum: MR mgd Sampling Frequency: 2/Month Sample Type: Estimate 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest flow was reported on 8/31/03 as 1.208 mgd.

### Rationale Page 33 of 44 Permit No. SC0001333

4. Actual long-term average flow (from 2003 flow schematic with anticipated future changes): 0.304 MGD 5. Conclusion: The permittee shall continue to monitor and report flow at this internal outfall. The monitoring frequency has been increased to daily (to be included in the total daily flow computed for Outfall 001). Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Estimate

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04) : The 2C application reported parameters for Outfall 001 only. 3. DMR Data: No past DMR data. 4. Effluent limitations guidelines: The permittee indicated in e-mails dated 5/6/04 & 7/26/04 that 85% of the flow at Outfall 01G is non-contact cooling water (0.304 mgd x 0.85 = 0.2584 mgd). Professional Judgment for the once-through non-contact cooling water portion of this discharge. Monthly Avg: 5 mg/l Daily Max: 10 mg/l Monthly average limit: 0.2584 mgd x 5 mg/l x 8.345 (lbs-L)/(MG-mg) = 11 lbs/day Daily maximum limit: 0.2584 mgd x 10 mg/l x 8.345 (lbs-L)/(MG-mg) = 22 lbs/day 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03) : No t applicable to this internal outfall. 7. Other information: None 8. Conclusion: Although a BOD 5 contribution has been determined for this outfall, BOD 5 does not need to be monitored at this outfall. A net BOD 5 limit is established at Outfall 001.

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : Monthly average: 25 mg/l Daily Maximum: 40 mg/l Sampling frequency: 1/Month Sample Type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest TSS was reported in 3/31/03 as 23 mg/l 4. Water Quality Data: NA 5. Effluent Limitation Guidelines: The previous permits had con centration limits of due to the presence of coal fines in this discharge. The permittee indicated in e-mails dated 5/6/04 & 7/ 26/04 that 85% of the flow at Outfall 01G is non-contact cooling water and that 11% of the flow is stormwater. There may be suspended solids in both discharges from this outfall. (0.304 mgd x 0.85 + 0.304 mgd x 0.11 = 0.2918 mgd). Monthly Avg: 25 mg/l Daily Max: 40 mg/l Monthly average limit: 0.2918 mgd x 25 mg/l x 8.345 (lbs-L)/(MG-mg) = 61 lbs/day Daily maximum limit: 0.2918 mgd x 40 mg/l x 8.345 (lbs-L)/(MG-mg) = 97 lbs/day 6. Other information: None 7. PQL: 1000 μg/l 8. Conclusion: The TSS limits shall be in accordance with the previous permit, however the permittee shall only sample for TSS when operating the coal fired boilers. A net TSS limit is established at Outfall 001. Monthly average: 25 mg/l, MR #/d Daily Maximum: 40 mg/l, MR #/d Sampling frequency: 1/Month Sample Type: Grab

### Rationale Page 34 of 44 Permit No. SC0001333

pH 1. Previous Permit Limits (effective 1/1/00 ) : MR standard units. Sampling Frequency: Daily Sample type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application re ported parameters for Outfall 001 only. 3. DMR Data: The highest and lowest pH were reported on 7/ 31/00 as 9.8 standard units and 6/30/01 as 4.6 standard units. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Not applicable to this outfall. 6. Other information: None 7. PQL: Not applicable 8. Conclusion: The permittee shall continue to MR pH (in standard units), however the monitoring frequency has been reduced to monthly to be consistent w ith other parameters at this outfall. Sampling Frequency: 1/Month Sample type: Grab

Oil and grease 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: 10 mg/l Daily maximum: 15 mg/l Sampling Frequency: 1/Month Sample type: Grab 2. NPDES Application ( 2C dated 3/26/04): The 2C application repor ted parameters for Outfall 001 only. 3. DMR Data: The highest oil and grease value was reported on 12/31/03 as 6 mg/l. 4. Water Quality Data: Not applicable to this internal outfall. 5. Effluent limitation guidelines: Standard Guidelines for Oil and Grease Monthly average: 10 mg/l Daily maximum: 15 mg/l 6. Other information: See Appendix G for oil and grease reasonable potential determination. 7. PQL: 5 mg/l 8. Conclusion: Reasonable Potential does not exist for this discharge to exceed the standa rd oil and grease guidelines; the receiving water concentrations (RWC = maximum concentra tion * MF) are less than the previous limits. The oil and grease limitations have been removed for this outfall.

OUTFALL 001 Information for this outfall based on NPD ES Permit Application: 2C dated 3/26/04

Description of outfall and treatment: Outfall 001 consists of a combination of all internal outfalls. Waterbody Data from Wasteload Allo cation dated 8/14/03 Receiving Waterbody: cfs MGD 7Q10 or other critical flow condition at discharge point ( Q 7Q10 ) 1601 1032.903 Average Annual Flow or other critical flow condition at discharge point ( AAF d ) 9499 6128.387

Is the discharge above a drinking water intake? Yes, Intake #S08104, Santee Cooper Regional, Congaree River Source Water Protection Waterbody Flow Data cfs MGD 7Q10or other critical flow condition at source water protection area boundary ( Q 7Q10i ) 2320 1496.77419

Average Annual Flow or other critical fl ow condition at source water protection area boundary ( AAF i ) 14684 9473.54839

### Rationale Page 35 of 44 Permit No. SC0001333

Dilution Factors (using formulas in Section G.2.a) using the total LTA flow of 91.67 mgd: DF 1 12.2676

DF 2 67.8527

DF 3 , if applicable 17.3279

DF 4 , if applicable 104.344

TSS Values for metals calculations: Effluent TSS concentration ( TSS e ) (mg/l) (based on monthly average value) 8.8 Background or In-stream TSS concentration ( TSS b ) (mg/l) (Default is 1 mg/l) 1.0 Calculated In-stream Average TSS concentration after mixing ( TSS avg ) (mg/l) 1.721

Appendix C contains the calculations for the water quality-based permit limitations and reasonable potential determinations.

Flow 1. Previous permit limits (effective 1/1/00 ) : No previous limits 2. NPDES Application ( 2C dated 3/26/04): (No. of flow analyses: 285) Long Term Average Value: 89.4 mgd Maximum Daily Value: 122.1 mgd 3. DMR Data: No past DMR data. 4. Actual long-term average flow (from 2003 DMR): Flow is not currently measured at Outfall 001. The total LTA flow used for water quality considerations is 91.67 mgd (a combined flow from all internal outfalls). 5. Conclusion: Flow will be MR using the sum of the intern al outfalls. A study is being re quired to confirm accurate flow measurement per Part II.J.1 of this permit. Monthly average: MR mgd Daily maximum: MR mgd Sampling Frequency: Daily Sampling Type: Estimate

Dissolved Oxygen (DO) 1. Previous Permit Limits (effective 1/1/00 ) : No limit 2. NPDES Application: not measured 3. DMR Data: No past DMR data. 4. Water Quality Data: Effluent Limits for D.O. ar e established in accordance with Reg. 61-68.G.10. For Class Fresh Water this value is a daily average not less than 5.0 mg/l with a low of 4.0 mg/l. 5. PQL: Not applicable. 6. Waste Load Allocation dated ( 8/14/03) : No limit recommended; model predicted DO > 5.0 mg/l instream. 7. Other information: None 8. Conclusion: Dissolved oxygen limits are not needed at this time.

Biochemical Oxygen Demand (BOD 5 ) 1. Previous permit limits (effective 1/1/00) : Monthly average: 4 mg/l net Daily maximum: 11mg/l net Sampling frequency: Daily Sample type: Calculation

### Rationale Page 36 of 44 Permit No. SC0001333

2. NPDES Application ( 2C dated 3/26/04) : (# of analyses: 362) Long Term Average Value: 0.1 mg/l Maximum 30-day value: 0.4 mg/l Maximum Daily Value: 5.6 mg/l 3. DMR Data: The highest BOD 5 was reported on 4/30/02 as 14 mg/l (net). 4. Effluent limitations guidelines/BPJ: summing the individual allowances for each internal outfall: Monthly average: 21 + 1036 + 2620 + 311 + 11 = 3999 #/d

3999 #/d = 5 mg/l 91.67 mgd x 8.345 (lbs-L)/(MG-mg)

Daily maximum: 43 + 2071 + 5240 + 820 + 22 = 8196 #/d

8196 #/d = 11 mg/l 91.67 mgd x 8.345 (lbs-L)/(MG-mg) 5. PQL: 2 mg/l 6. Waste Load Allocation dated ( 8/14/03) Monthly Average: 4 mg/l net 7. Other information: The permittee has had one violation of the daily maximum limits (14 mg/l reported on 4/30/02) during the last permit period, but no violations of the monthl y average limit. The source of the violation is unknown. 8. Conclusion: The BOD 5 limits remain in accordance with the previous permit and the WLA. The permittee has shown they are able to meet these limits. Monthly average: 4 mg/l net Daily maximum: 11 mg/l net Sampling Frequency: Daily Sampling Type: Calculation

Total Suspended Solids (TSS) 1. Previous permit limits (effective 1/1/00 ) : 7 Day rolling average limit of 22 mg/l Sampling frequency: Daily Sample Type: Calculation 2. NPDES Application ( 2C dated 3/26/04): (No. of TSS analyses: 363) Long Term Average Value: 8.8 mg/l Maximum Daily Value: 125.4 mg/l 3. DMR Data: The highest TSS was reported in 7/31/00 as 12 mg/l (net). 4. Water Quality Data: NA 5. Effluent limitations guidelines/BPJ: summing the individual allowances for each internal outfall:

Daily maximum: 85 + 4142 + 10479 + 1605 + 97 = 16408 #/d

16408 #/d = 21 mg/l 91.67 mgd x 8.345 (lbs-L)/(MG-mg) 6. Other information: The permittee has not had any TSS violations during the last permit period. 7. PQL: 1000 μg/l 8. Conclusion: The TSS limits are in accordance with the calcu lated limits above. A 7-day rolli ng average of 21 mg/l will be used to account for TSS variations in influent concentration and cooling water residence time. Sampling Frequency: Daily Sample type: Calculation

### Rationale Page 37 of 44 Permit No. SC0001333

pH 1. Previous Permit Limits (effective 1/1/00 ) : 6.0-9.0 standard units. Sampling Frequency: Daily Sample type: Continuous 2. NPDES Application ( 2C dated 3/26/04): (No. of pH analyses: 365) Minimum: 6.6 standard units. Maximum: 9.7 standard units. 3. DMR Data: The highest and lowest pH was reported on 12/31/03 as 9.7 su and 9/30/03 as 6 su. 4. Water Quality Data: Effluent Limits for pH are established in accordance with Reg. 61-68.G.10. For Class Fresh Water this value is 6.0-8.5 standard units. 5. Effluent limitation guidelines: 40CFR Part 414 Subparts A, D and F: 6.0-9.0 su 6. Other information: The permittee has had one pH violation during the last permit period (9.7 su reported on 12/31/03) 7. PQL: Not applicable 8. Conclusion: Due to the large stream dilution in comparison to the discharge, a maximum pH of 9.0 su shall be granted.

This small change should not have any adverse impact on the receiving stream. This pH limits are as follows: pH should be between 6.0 and 9.0 standard units Sampling Frequency: Daily Sample type: Continuous* *In accordance with 401.17, pH Effluent limitations unde r continuous monitoring are specified as follows. Where a permittee continuously measures the pH of wastewat er pursuant to a requirement or option in a National Pollutant Discharge Elimination System (NPDES) permit issu ed pursuant to section 402 of the Act, the permittee shall maintain the pH of such wastewater within the range set forth in the applicable effluent limitations guidelines, except excursions from the range are permitted subject to the following limitations: (a) The total time during which the pH values are outside the required range of pH values shall not exceed 7 hours and 26 minutes in any calendar month; and (b) No individual excursion from the range of pH values shall exceed 60 minutes. For purposes of this section, an excursion is an uninten tional and temporary incident in which the pH value of discharge wastewater exceeds the range set forth in the applicable effluent limitations guidelines. (Secs. 301, 304, 306 and 501 of the Clean Water Act (the Federal Water Pollution Control Act Amendments of 1972, 33 U.S.C. 1251 et. seq., as amended by the Clean Water Act of 1977, Pub. L. 95-217))
Temperature 1. Previous Permit Limits (effective 1/1/00 ) : Monthly average: 98 F Daily Maximum: 105 F Sampling Frequency: Daily Sample Type: Continuous 2. NPDES Application ( 2C dated 3/26/04): (No. of analyses: 92) Summer: Average: 28.7 C Maximum: 32.8 C Winter: Average: 10.6 C Maximum: 14.4 C 3. DMR Data: The highest temperature was reported in 7/31/00 as 94 F 4. Water Quality Data: Effluent Limits for temperature are established in accordance with Reg. 61-68.E.10.a. For Class Fresh Water
, “The water temperature of all Freshwaters which are free flowing shall not be increased more than 5 o F (2.8 o C) above natural temperature conditions and shall not exceed a maximum of 90 o F (32.2 o C) as a result of the discharge of heated liquids unless a different temperature standard as provided for in C.12 has been established, a mixing zone as provided in C.10 has been established, or a Section 316(a) determination under the Federal Clean Water Act has been completed.”

### Rationale Page 38 of 44 Permit No. SC0001333

5. Effluent limitation guidelines: not applicable 6. Other information: At 7Q10 conditions with an upstream ambient water temperature of 79.34 F (from the WLA Section) and a 92.31 MGD discharge at 105 F, a heat balance around the outfall gives: Q 1 + Q 2 = Q 3 where Q 1 = upstream thermal load Q 2 = discharge thermal load Q 3 = downstream thermal load The heat transfer can be estimated from the following equation:

Q = mC p T where Q = heat (Btu/hr) m = flowrate (lb/hr) C p = specific heat [Btu/(lb *R)] T = temperature (R)

m 1 = 7Q10 = 1033 MGD

Combining and re-arranging the two equations gives:

T 3 = m 1 (T 1 + 460 F) + m 2 (T 2 + 460 F) 1 - 460 F

m 1 + m 2
= (1033MGD)(79.34 F + 460 F) + (91.67 MGD)(105 F + 460 F) - 460 F (1033 +91.67 MGD) = 81.43 F 7. PQL: Not applicable 8. Conclusion: Due to the nature of the discharge, temperatur e shall be limited on this permit. The above equation shows that a discharge with a temperature of 105 F will not cause an instream excursion above the daily maximum of 90 ° F or violate the difference in natural conditions with a change of 5 ° F. The temperature limits for this permit shall be: Monthly Average: 98 F Daily Maximum: 105 F Sample Frequency: Daily Sample Type: Continuous

Total Phosphorus 1. Previous Permit Limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): (No. of analyses:1) Maximum Daily Value: 0.1 mg/l 3. DMR Data: No past DMR data. 4. Water Quality Data: See Section II.G.1.c of this rationale. 5. Effluent limitation guidelines: not applicable 6. Wasteload Allocation dated ( 8/14/03 ) : MR mg/l 7. Other information: Lake Marion (downstream of this discharge) is impaired for phosphorus (Station SC-008). 8. PQL: 0.050 mg/l (EPA Method 365.1 - 365.4 or 300) 9. Conclusion: Since the permittee reported an intake value of 0.1 mg/l (equal to their effluent value) the Department has included MR requirements to collect intake and effluent da ta showing they are not causing or contributing to this impairment. The following reopener clause will be included in the permit:

This permit may be reopened to include additional monitori ng and/or limitations or to eliminate monitoring for phosphorus based on monitoring results obtained. Monthly average: MR mg/l net Daily Maximum: MR mg/l net Sample type: Calculation Sampling Frequency: 1/Quarter

### Rationale Page 39 of 44 Permit No. SC0001333

Total Copper 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): (No. of analyses:1) Maximum Daily Value: 0.010 mg/l 3. DMR Data: No past DMR data 4. Water Quality Criterion: see spreadsheet 5. Other Information: The Congaree Rive r is impaired for Copper (Station C-074). 6. Does the discharge cause, have the R easonable Potential to Cause or Contribute: Although the Congaree River is impaired, the permittee’s application indicates an intake value of 0.011 mg /l (greater than their effluent value); therefore we will include MR requirements for the intake and this outfall to de termine if this discharge is causing or contributing to the impairment. 7. Effluent limitations guidelines (ELGs) and professional judgm ent-based limits: Not applicable to this parameter. 8. PQL: 0.010 mg/l 9. Conclusion: The Department has included MR requirements to collect intake and effluent data showing they are not causing or contributing to this impairment. The fo llowing reopener clause will be included in the permit:

This permit may be reopened to include additional monitoring and/or limitations or to eliminate monitoring for copper based on monitoring results obtained. Monthly average: MR mg/l net Daily Maximum: MR mg/l net Sample type: Calculation Sampling Frequency: 1/Quarter

Mercury 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): (No. of analyses:1) Maximum Daily Value: 0.0004 mg/l 3. DMR Data: No past DMR data 4. Water Quality Criterion: see spreadsheet 5. Other Information: The Congaree River is impaired for Mercury (Station C-007). 6. Does the discharge cause, have the R easonable Potential to Cause or Contribute: Although the Congaree River is impaired, the permittee’s application indicates an intake value of 0.0005 mg /l (greater than their effluent value); therefore we will include MR requirements for the intake and this outfall to de termine if this discharge is causing or contributing to the impairment. 7. Effluent limitations guidelines (ELGs) and professional judgm ent-based limits: Not applicable to this parameter. 8. PQL: 0.0000005 mg/l 9. Conclusion: The permittee shall monitor and report the intake and effluent for mercury as the Congaree River is impaired for mercury. The following reopener clause will be included in the permit:

This permit may be reopened to include additional monitoring and/or limitations or to eliminate monitoring for mercury based on monitoring results obtained. Monthly average: MR mg/l net Daily Maximum: MR mg/l net Sample type: Calculation Sampling Frequency: 1/Quarter

Iron 1. Previous permit limits (effective 1/1/00 ) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04): (No. of analyses:1) Maximum Daily Value: 0.314 mg/l

### Rationale Page 40 of 44 Permit No. SC0001333

3. DMR Data: No past DMR data 4. Water Quality Criterion: see spreadsheet 5. Other Information: The permittee reported an intake value of 0.314 mg/l (intake= effluent concentration). 6. Does the discharge cause, have the Reas onable Potential to Cause or Contribute: Although the spreadsheet indicates the permittee demonstrates reasonable potential, their application indicates an intake value equal to their effluent value. 7. Effluent limitations guidelines (ELGs) and professional judgm ent-based limits: Not applicable to this parameter. 8. PQL: 0.020 mg/l 9. Conclusion: The permittee is only discharging the con centration of iron present in the background (intake water), therefore iron monitoring and/or limits are not needed at this time.

Aluminum 1. Previous permit limits (effective 1/1/00) : No previous limits. 2. NPDES Application ( 2C dated 3/26/04) : (No. of analyses:1) Maximum Daily Value: 0.198 mg/l 3. DMR Data: No past DMR data 4. Water Quality Criterion: see spreadsheet 5. Other Information: The permittee reported an intake value of 0.352 mg/l (intake > effluent concentration). 6. Effluent limitations guidelines (ELGs) and professional judgm ent-based limits: Not applicable to this parameter. 7. PQL: 0.020 mg/l 8. Conclusion: Aluminum monitoring and/or limits are not n eeded at this time as the State had not adopted water quality criteria for aluminum and the permittee is discharging less al uminum than is present in the background (intake water).
Whole Effluent Toxicity (WET) Testing 1. Previous permit limits (effective 1/1/00 ) : Chronic Multiconcentration Limits at CTC = 27% Monthly average: 25% Effect Daily Maximum: 40% Effect Sample type: 24 Hour Composite Sampling Frequency: 1/Month The dilution series was 7, 14, 27, 54 and 100% 2. DMR Data: The highest percent effect reported for chronic toxicity was 20% on 9/30/01.

Date M. Avg D. Max.
1/31/2000 0 0 2/29/2000 0 0 3/31/2000 0 0 4/30/2000 0 0 5/31/2000 0 0 6/30/2000 0 0 7/31/2000 0 0 8/31/2000 0 0 9/30/2000 11 11 10/31/2000 0 0 11/30/2000 0 0 12/31/2000 10 10

1/31/2001 0 0 2/28/2001 0 0 3/31/2001 0 0 4/30/2001 15 15 5/31/2001 12 12 6/30/2001 0 0 7/31/2001 11 11

### Rationale Page 41 of 44 Permit No. SC0001333

8/31/2001 6 6 9/30/2001 20 20 10/31/2001 6 6 11/30/2001 0 0 12/31/2001 6 6

1/31/2002 0 0 2/28/2002 0 0 3/31/2002 0 0 4/30/2002 5 11 5/31/2002 0 0 6/30/2002 10 10 7/31/2002 6 6 8/31/2002 0 0 9/30/2002 6 6 10/31/2002 0 0 11/30/2002 10 10 12/31/2002 0 0

1/31/2003 7 7 2/28/2003 0 0 3/31/2003 0 0 4/30/2003 18 18 5/31/2003 7 7 6/30/2003 12 12 7/31/2003 11 11 8/31/2003 0 0 9/30/2003 0 0 10/31/2003 0 0 11/30/2003 0 0 12/31/2003 12 12

1/31/2004 0 0 2/29/2004 0 0 3/31/2004 0 0 4/30/2004 0 0 5/31/2004 0 0 3. Conclusion: The South Carolina General Assembly passed legislation on June 3, 2004, entitled the South Carolina Aquatic Life Protection Act. The Act was signed into law by the Governor and, thus, b ecame effective on June 15, 2004. Part (E) of Section 2 of the Act (Section 48-1-87 of the Code of Laws of South Carolina) requires DHEC to establish formal data quality objectives and an enhanced laboratory certification program. Because these requirements have not been satisfied, DHEC cannot evaluate the results of W ET tests nor determine reasonable potential for WET since reasonable potential evaluations involve evaluating WET t est results. As such, DHEC cannot establish WET testing requirements for NPDES permits until such time as the requirements of Part (E) are met. Therefore, this permit contains no WET testing requirements and/or limitations. Land Application of Sludge: Some of the requirements in Consent Agreement 01-041-W have been included in this NPDES for the land application of sludge onsite. The permittee uses the land application site as .a backup to the incinerator (they are only allowed to land appl y during equipment failure or incinerator maintenance). Application of sludge cannot exceed six weeks in durations and not more often than three times per year. Groundwater monitoring a nd sludge monitoring requirements have been included in the permit. Voridian accepts sludge from Carolina Eastman Compan y SC0002321 (if the incinerator is down, this sludge would also be land applied).

### Rationale Page 42 of 44 Permit No. SC0001333

IV. PROCEDURES FOR REACHING A FINAL PERMIT DECISION

A. Comment Period (R.61-9.124.10 and 11)

The Department of Health and Environmental Control proposes to issue an NPDES permit to this applicant subject to the effluent limitations and special conditions outlined in this document. These determinations are tentative.

During the public comment period, any interested pers on may submit written comments on the draft permit to the following address:

SC Dept. of Health and Environmental Control Industrial, Agricultural and Storm Water Permitting Division Bureau of Water 2600 Bull Street Columbia, South Carolina 29201

For additional information, interested persons may contact Melanie Kastler at 803-898-4223.

All written comments received during the period beginning ??? and ending on ??? shall be considered in making the final decision and shall be answered as pr escribed below. See Public Notice #???.

Per R.61-9.124.17, the Department is only required to issue a response to comments when a final permit is issued. This response shall:

1. Specify which provisions, if any, of the draft permit have been changed in the final permit decision, and the reasons for the change; and

2. Briefly describe and respond to all significant comments on the draft permit raised during the public comment period, or during any hearing.

The response to comments shall be available to the public.

B. Public Hearings (R.61-9.124.11 and 12)

During the public comment period, any interested person may request a public hearing, if no hearing has already been scheduled. A request for a public hearing shall be in writing and shall state the nature of the issues proposed to be raised in the hearing.

Determinations and Scheduling.

1. Within the thirty (30) day comment period or ot her applicable comment period provided after posting or publishing of a public notice, an applicant, any affected st ate or interstate agency, the Regional Administrator or any other interested person or agency may file a pe tition with the Department for a public hearing on an application for a permit. A petition for a public heari ng shall indicate the specific reasons why a hearing is requested, the existing or proposed discharge identified therein and specifically indicate which portions of the application or other permit form or information constitu tes necessity for a public hearing. If the Department determines that a petition constitutes significant cause or that there is sufficient public inte rest in an application for a public hearing, it may direct the scheduling of a hearing thereon.

### Rationale Page 43 of 44 Permit No. SC0001333

2. A hearing shall be scheduled not less than four (4) nor more than eight (8) weeks after the Department determines the necessity of the hearing in the geographical location of the applicant or, at the discretion of the Department, at another appropriate location, and shall be noticed at least th irty (30) days before the hearing. The notice of public hearing shall be transmitted to the applicant and shall be published in at least one (1) newspaper of general circulation in the geographical area of the existing or proposed discharge identified on the permit application and shall be mailed to any person or group upon request ther efore. Notice shall be mailed to all persons and governmental agencies which received a copy of the no tice or the fact sheet for the permit application.

3. The Department may hold a single public hear ing on related groups of permit applications.

4. The Department may also hold a public hearing at its discretion, whenever, for instance, such a hearing might clarify one or more issues involved in the permit decision;

5. Public notice of the hearing shall be given in accordance with R.61-9.124.10.

Any person may submit oral or written statements and data concerning the draft permit. Reasonable limits may be set upon the time allowed for oral statements, and the submission of statements in writing may be required. The public comment period under R.61-9.124.10 shall automatically be ex tended to the close of any public hearing under this section. The hearing officer may also extend the comment period by so stating at the hearing.

A tape recording or written transcript of the hearing shall be made available to the public.

C. Obligation to raise issues and provide informati on during the public comment period. (R.61-9.124.13)

All persons, including applicants, who belie ve any condition of a draft permit is in appropriate or that the Department’s tentative decision to deny an application, terminate a permit, or prepare a draft permit is inappropriate, must raise all reasonably ascertainable issues and submit all reasonably av ailable arguments supporting their position by the close of the public comment period (including any public hearing). No i ssue shall be raised during an appeal by any party that was not submitted to the administrative record as part of the preparation and comment on a draft permit, unless good cause is shown for the failure to submit it. Any supporting ma terials which are submitted shall be included in full and may not be incorporated by reference, unless they are alread y part of the administrative r ecord in the same proceeding, or consist of State or Federal statutes and regulations, Department and EPA documents of general applicability, or other generally available reference materials. Commenters shall make supporting materials not already included in the administrative record available. (A comment period longer than 30 days may be necessary to give commenters a reasonable opportunity to comply with the requirements of this section. Additional time shall be granted under R.61- 9.124.10 to the extent that a commenter who requests additional time demonstrates the need for such time).

D. Issuance and Effective Date of the Permit

1. After the close of the public comment period on a draft permit, the Department shall issue a final permit decision. The Department shall notify the applicant and each person who has submitted written comments or requested notice of the final permit decision. This notice shall in clude reference to the procedures for appealing a decision on a permit. For the purposes of this section, a final perm it decision means a final decision to issue, deny, modify, revoke and reissue, or terminate a permit.

2. A final permit decision shall become effective 30 da ys after the service of notice of the decision unless:

(a) A later effective date is specified in the decision; or (b) No comments requested a change in the draft permit, in which case the permit shall become effective on the effective date shown in the issued permit.

### Rationale Page 44 of 44 Permit No. SC0001333

3. Issuance or Denial of Permits. An appeal to a final de termination of the Department or to a condition of a permit issued or the denial of a permit pursuant to the State law and this regulation, shall be in accordance with and subject to 48-1-200 of the SC Code.

4. Unless specific circumstances warrant otherwise, the permit will become effective on the first of the month following the 15-day appeal period (see E below) or 30- day time required by D.2 above , whichever is longer if no request for adjudicatory hearing is filed. If a request for adjudicatory hearing is filed, the permit will become effective on the first of the month following resolution of the appeal.

E. Adjudicatory Hearings

Any person may submit a request for an administrative adj udicatory hearing to consider the final permit and its conditions. If you wish to request an administrative ad judicatory hearing, you must do so in accordance with Regulation 61-72, Volume 25, S.C. Code of Laws, 1976, as amended, and the Rules of the Administrative Law Judge (ALJ) Division. The request must be filed with the Cler k of the South Carolina Board of Health and Environmental Control, 2600 Bull Street, Columbia, South Carolina 29201, with in fifteen (15) days following issuance of the permit. Service may be effected by personal delivery or by first class mail, but the request must be received by the Clerk on or before the fifteenth day.

The following information, at a minimum, must be included in the request:

1. the name of the party or parties requesting the hear ing and the issue(s) for which the hearing is requested;

2. the caption or other information sufficient to identify the permit decision being appealed; and

3. the relief requested.

In addition, the Administrative Law Judge Division requires th at a person requesting a contested case hearing must file a copy of the request and a filing fee in the amount of $250.00 with the Administrative Law Judge Division at the following address:

Clerk, Administrative Law Judge Division 1205 Pendleton Street, Suite 224 P.O. Box 11667 Columbia, SC 29211

A petition for review of a decision to issue a new permit stay s all actions for which the permit is a prerequisite. A petition for review of a decision to reissue a permit stays the entire permit; the conditions of the expiring/expired permit remain in effect until the appeal is resolved. An y party may petition the ALJ Division to allow all uncontested provisions of the permit to be placed into effect. Inform ation pertaining to adjudicatory matters may be obtained by contacting the Legal Office of the Department of Health and Environmental Control, 2600 Bull Street, Columbia, South Carolina or by calling 803-898-3350.