NC0024911_Fact Sheet_20240128

Fact Sheet
NPDES Permit No. NCO024911
Permit Writer/Email Contact: Nick Coco, [e-mail]
Date: June 22, 2023
Division/Branch: NC Division of Water Resources/NPDES Municipal Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
® Renewal
❑ Renewal with Expansion
❑ New Discharge
❑ Modification (Fact Sheet should be tailored to mod request)
Note: A complete application should include the following:
• For New Dischargers, EPA Form 2A or 2D requirements, Engineering Alternatives Analysis, Fee
• For Existing Dischargers (POTW), EPA Form 2A, 3 effluent pollutant scans, 4 2nd species WET
tests.
• For Existing Dischargers (Non-POTW), EPA Form 2C with correct analytical requirements based
on industry category.
Complete applicable sections below. If not applicable, enter NA.
1. Basic Facility Information
Facility Information
Applicant/Facility Name:
Metropolitan Sewerage District Buncombe County (MSD)/French
Broad River Water Reclamation Facility (WRF)
Applicant Address:
2028 Riverside Dr., Asheville, NC 28804
Facility Address:
2225 Riverside Dr., Woodfin, NC 28804
Permitted Flow:
40.0 MGD
Facility Type/Waste:
MAJOR Municipal; 97.8% domestic, 2.2% industrial*
Facility Class:
Grade IV Biological Water Pollution Control System
Treatment Units:
Two multi -rake mechanical bar screens, Two vortex grit basins, Three
influent pumps with capacity of 35 MGD each, Instrumental flow
measurement, Three perforated -plate mechanical fine screens, 1st, 2nd,
and 3rd stage RBCs (152 total), Three intermediate pumps, Four
intermediate clarifier cells (total volume 2 MG), Effluent chlorination
(liquid sodium hypochlorite), Effluent de -chlorination (liquid sodium
bi-sulfate)), Two gravity sludge thickeners -100 ft diameter each, Two
2.1 MG surge tanks, Three surge pumps with capacity of 5 MGD each,
Two 2.5-meter belt filter presses (gravity and pressure sections),
Fluidized bed incinerator (40 DT/day rated), One 2 MW back-up
generator (diesel), Two 1 MW back-up generators (diesel), 192 cloth -
media filter disks (10 micron), Two 450 KW gas generators, Three 850
KW hydro turbines (French Broad River source), 17-acre ash storage
lagoon, SCADA
Pretreatment Program (Y/N)
Y; LTMP
County:
Buncombe
Region
Asheville
*Based off of permitted flows.
Page 1 of 14

Briefly describe the proposed permitting action and facility background: MSD Buncombe County has
applied for an NPDES permit renewal at 40.0 MGD for the French Broad River WRF. This facility serves
a population of approximately 173,000 residents, as well as 23 significant industrial users (SIUs),
including 14 categorical industrial users (CIUs), via a Division -approved pretreatment program. Treated
domestic and industrial wastewater is discharged into the French Broad River, a class B waterbody in the
French Broad River Basin. Outfall 001 is approximately 10 miles upstream of the NC/TN border.
In their application, MSD indicated an average daily volume of I&I of approximately 6 MGD. MSD has
continuous rehabilitation projects of replacing damaged piping/connections as identified by sewer camera
identification, cleaning approximately 50,000 liner feet of line/year and a commitment of $15million/year
on collection system projects.
MSD maintains a 17-acre sludge lagoon. At one point this lagoon was used to store ash (from an onsite
incinerator), grit, line cleanouts, grease, and site stormwater. The outfall from the lagoon returns to the
head of the plant. A septage receiving station has been built for the vacuum truck debris, site management
procedures were implemented in Fall 2003. Therefore grease, grit, and line cleanouts are no longer stored
in the lagoon. The permit contains Special Condition A.(8.) Ash Storage Lagoon, allowing the use of the
lagoon for ash storage.
Sludge disposal: Residuals are thickened and dewatered then incinerated.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001 — French Broad River
Stream Segment:
6-(54.75)
Stream Classification:
B
Drainage Area (mi2):
966
Summer 7Q10 (cfs)
466
Winter 7Q10 (cfs):
595
30Q2 (cfs):
882
Average Flow (cfs):
2140
IWC (% effluent):
12
2022 303(d) listed/parameter:
Not listed*
Subject to TMDL/parameter:
Yes- State wide Mercury TMDL implementation.
Basin/ HUC:
French Broad River/06010105
USGS Topo Quad:
ERNE
*While the portion of the French Broad River to which the French Broad River WRF discharges is not
considered impaired, the stream segment 6 miles downstream of the discharge [6-(54.75)e] is considered
impaired for Benthos in the 2022 303(d) list.
3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of January 2019 through June 2023.
Table 1. Effluent Data Summary Outfall 001
Permit
Parameter
Units
Average
Max
Min
Limit
Flow
MGD
23.1
67.54
14.5
MA 40.0
WA 40.0
CBOD
mg/1
14.4
87.2
< 2
MA 25.0
Page 2 of 14

Monitor &
NH3N
mg/1
19.7
49.8
6
Report
TSS
mg/1
13.2
142
3.7
WA 45.0
MA 30.0
6.0 > pH <
pH
SU
7.3
7.77
6.16
9.0
(geometric)
an)
Fecal coliform
#/100 ml
2420
< 1
WA 400
2.(ge 2
MA 200
DO
mg/1
7.8
9.9
5.8
DA >5.0
DM 28.0
TRC
µg/1
20.1
28
20
(< 50
compliance)
Monitor &
Conductivity
µmhos/cm
502
755
7.38
Report
Monitor &
Temperature
° C
18
24.2
4.4
Report
Monitor &
NO2+NO3
mg/1
1.8
4.5
0.51
Report
Monitor &
TKN
mg/1
25.4
58.4
12.5
Report
Monitor &
TN
mg/1
27.2
59.3
13.4
Report
Monitor &
TP
mg/1
3.1
5.7
0.98
Report
Monitor &
Total Hardness
mg/1
53.6
418
34.4
Report
MA -Monthly Average, WA -Weekly Average, DM -Daily Maximum, DA=Daily Average
4. Instream Data Summary
Instream monitoring may be required in certain situations, for example: 1) to verify model predictions
when model results for instream DO are within 1 mg/1 of instream standard at full permitted flow; 2) to
verify model predictions for outfall diffuser; 3) to provide data for future TMDL; 4) based on other
instream concerns. Instream monitoring may be conducted by the Permittee, and there are also
Monitoring Coalitions established in several basins that conduct instream sampling for the Permittee (in
which case instream monitoring is waived in the permit as long as coalition membership is maintained).
If applicable, summarize any instream data and what instream monitoring will be proposed for this
permit action: The current permit requires instream monitoring for dissolved oxygen, temperature, and
conductivity in accordance with 15A NCAC 02B .0508. Instream sampling is conducted upstream at dam
discharge to fish ladder adjacent to intake flume to the hydroelectric plant (Location is approximately
2700 feet upstream of the hydroelectric plant, - 0.5 miles upstream of the discharge) and downstream at
Ledges Park (approximately 4 miles downstream). Upstream and downstream dissolved oxygen samples
are collected three times per week during June, July, August and September then once per week in the
remaining months of the year. Upstream and downstream temperature and conductivity samples are
collected daily. In addition to DO, temperature and conductivity, quarterly monitoring for hardness
upstream of the facility is conducted. MSD Buncombe County also provided instream sampling data for
Page 3 of 14

fecal coliform in their electronic DMRs. Instream data from January 2019 through May 2023 has been
summarized below in Table 2.
Table 2. Instream Monitoring Data Summary
Parameter
Units
Upstream
Downstream
Average
Max
Min
Average
Max
Min
Temperature
° C
15.3
28.7
1.4
15.4
25.6
0.9
DO
mg/1
9.1
21.7
5.56
9.4
61.3
1.26
Conductivity
µmhos/cm
44.3
119.4
26
51.3
135.4
9
Fecal Coliform
#/100 ml
(geomean)
188
60000
5
(geomean)
154
60000
5
Hardness
mg/1
11.8
25
9.54
-
I -
I -
Students t-tests were run at a 95% confidence interval to analyze relationships between instream
samples. A statistically significant difference is determined when the t-test p-value result is < 0.05.
Temperature is a parameter of concern for aquatic life. Downstream temperature was not greater than 29
degrees Celsius [per 15A NCAC 02B .0211 (18)] during the period reviewed. Downstream temperature
was not greater than upstream temperature by more than 2.8 degrees Celsius [per 15A NCAC 02B .0211
(18)] during the period reviewed. It was concluded that no statistically significant difference exists
between upstream and downstream temperature.
Dissolved oxygen is a parameter of concern for aquatic life. Average downstream DO was above 5 mg/L
[per 15A NCAC 02B .0211 (6)] during the period reviewed. Downstream DO was observed at levels less
than 4.0 mg/L on one occasion during the period reviewed. Concurrent effluent concentrations oxygen -
consuming wastes (BOD5 and ammonia) were not observed at elevated levels, and it does not appear that
the effluent influenced the individual low downstream DO instance. It was concluded that no statistically
significant difference exists between upstream and downstream DO.
As the facility receives influent flow from several industrial users via an approved pretreatment program,
instream conductivity is tracked. It was concluded that a statistically significant difference exists between
upstream and downstream conductivity.
Fecal Coliform is a parameter of concern for aquatic life and human health. Instream monitoring for fecal
coliform was removed from the permit in 2018 based on the receiving stream not having been impaired
for fecal coliform. However, MSD conducted sampling and provided the Division with ambient fecal
coliform data. Based on this data review, it was concluded that no statistically significant difference exists
between upstream and downstream fecal coliform. Downstream fecal coliform was observed at levels
greater than 400/100mL in 25% of samples reported, and upstream fecal coliform was observed at levels
greater than 400/100mL in 28% of samples reported. While ambient fecal coliform was observed at
elevated levels during the period reviewed, concurrent effluent fecal coliform concentrations were
consistently lower than the instream. However, the French Broad River WRF discharges to class B
waters, and in accordance with the 2002 Instream Conductivity and Fecal Coliform Monitoring Guidance,
instream fecal coliform monitoring may only be removed from municipal or domestic wastewater permits
that do not discharge to waterbodies impaired due to fecal coliform or Class B waterbodies. As such,
instream monitoring for fecal coliform has been added back into the permit.
For verification of site -specific ammonia calculations, upstream ammonia and pH sampling has been
added to the permit. To track facility impact on ambient ammonia levels in the French Broad River while
MSD implements corrective actions to achieve compliance with future ammonia effluent limits,
downstream ammonia sampling has been added to the permit. For consistency amongst parameters, all
Page 4 of 14

upstream and downstream samples shall be collected three times per week during June, July, August and
September then once per week in the remaining months of the year.
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): NO
Name of Monitoring Coalition: N/A
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years): The facility reported one
Total Residual Chlorine limit violation in 2018 and one CBOD limit violation in 2021 resulting in
enforcement.
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): The facility passed 17 of 17 quarterly chronic toxicity tests, as well as all 4 second species
chronic toxicity tests from February 2019 to February 2023.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in February 2023 reported that the facility was compliant.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and MixingZones
In accordance with 15A NCAC 213.0206, the following streamflows are used for dilution considerations
for development of WQBELs: 1Q10 streamflow (acute Aquatic Life); 7Q10 streamflow (chronic Aquatic
Life; non -carcinogen HH); 30Q2 streamflow (aesthetics); annual average flow (carcinogen, HH).
If applicable, describe any other dilution factors considered (e.g., based on CORMIX model results): NA
If applicable, describe any mixing zones established in accordance with 15A NCAC 2B.0204(b): NA
Oxygen -Consuming Waste Limitations
Limitations for oxygen -consuming waste (e.g., BOD) are generally based on water quality modeling to
ensure protection of the instream dissolved oxygen (DO) water quality standard. Secondary TBEL limits
(e.g., BOD= 30 mg/1 for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
If permit limits are more stringent than TBELs, describe how limits were developed: In lieu of BOD the
permit has secondary treatment standard limits for CBOD of 25 mg/1 as per 40 CFR 133.102. No changes
are proposed.
Ammonia and Total Residual Chlorine Limitations
Limitations for ammonia are based on protection of aquatic life utilizing an ammonia chronic criterion of
1.0 mg/1(summer) and 1.8 mg/1(winter). Acute ammonia limits are derived from chronic criteria,
utilizing a multiplication factor of 3 for Municipals and a multiplication factor of 5 for Non -Municipals.
Limitations for Total Residual Chlorine (TRC) are based on the NC water quality standard for protection
of aquatic life (17 ug/1) and capped at 28 ug/1(acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/1 are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: TRC limits have
been reviewed in the attached WLA and have been found to be protective. No changes are proposed.
Page 5 of 14

During the 2011 permit renewal, an Ammonia Reduction Evaluation condition was included for
evaluation of the feasibility and cost for the following ammonia reduction scenarios:
optimizing ammonia removal at the current plant via operational improvements; and
(22,) upgrading the plant to meet summer ammonia limits of 6.9 mg/L (Monthly Average) and 20.7 mg/L
(Weekly Average),and winter limits of 17 mg/L (Monthly Average) and 35 mg/L (Weekly Average).
Summer is defined as April 1 through October 31.
MSD submitted the evaluation on April 8, 2015. In their evaluation, MSD found that their current
treatment process, Rotating Biological Contactors (RBC), does not provide NH3-N removal, and an
Ammonia Reduction Evaluation was completed in 2016 as required by the 2011 permit renewal. The
evaluation report indicated that a compliance schedule of at least 12 years would be needed for the facility
to upgrade the plant and optimize NH3-N removal to meet proposed limits. The current permit includes a
12-year schedule of compliance for ammonia limits which is set to end October 1, 2030. The limits being
incorporated at the end of the schedule of compliance are summer monthly average and weekly average
limits of 14.0 mg/L and 35.0 mg/L, respectively, and winter monthly average and weekly average limits
of 31.7 mg/L and 35.0 mg/L, respectively. These limits are based on calculations performed using site -
specific data available during the 2018 renewal process.
The existing site -specific ammonia limits, to take effect after the conclusion of the schedule of
compliance, have been reviewed in accordance with EPA's guidance "Aquatic Lift Ambient Water Quality
Criteria For Ammonia — Freshwater 2013 ". This review incorporated facility effluent temperature and
pH data from 9/2018 to 2/2023, DMR upstream temperature data from 9/2018 to 2/2023, and upstream
ammonia and pH data from AMS station E4280000 from 1/2015 to 2/2020 (most recent data available).
For calculation of site -specific ammonia limits, the 90th percentile of summer and winter upstream and
effluent pH and temperature and upstream ammonia is used. These values have been summarized in Table
3, shown below.
Table 3. Site -Specific Data Summary
Summer
Winter
Ammonia
pH
Temp
pH
Temp
Summer
Winter
Effluent 90th
7.47
23.3
7.47
17.8
-
-
Upstream
90th
7.60
23.2
7.35
11.9
0.05
0.19
Based on site -specific calculations, summer ammonia monthly average and weekly average limits have
been revised to 8.5 mg/L and 21.4 mg/L, respectively. Per 15A NCAC 02B .0404(c), "The winter
oxygen -consuming wasteload allocation shall not exceed two times the summer oxygen -consuming
wasteload limitations nor shall it be less restrictive than minimum treatment requirements." As such,
winter ammonia monthly average and weekly average limits have been revised to 17.0 mg/L and 35.0
mg/L, respectively.
In their renewal application, MSD requested extension of the ammonia schedule of compliance deadline
to October 1, 2035. The Permittee informed the Division of a number of issues that have arisen during
their corrective action process including:
• In November 2020, a major fire in an MSD storage facility destroyed new equipment for the
High -Rate Primary Treatment (HRPT) project, leading to a 9-month delay related to re -
procurement of the parts,
• The Covid-19 global pandemic caused significant delays to the construction process by
interrupting equipment and material supply chains and staffing levels available at the job site,
Page 6 of 14

• The HRPT is not fully commissioned, preventing MSD from gathering performance data to
inform design,
• Anticipated capital costs are high and volatile, with supply chains issues skewing costs upward.
The Permittee conducted a Microsoft Teams call with NPDES Permitting staff and Asheville Regional
Office staff on March 17, 2023 to discuss the state of their corrective action plan and to discuss the need
of extension to the deadline for the schedule of compliance. During this call, the Division discussed the
revisions to the ammonia limitations and requested that MSD provide an Ammonia Treatment Evaluation
Study, which would identify the plant's current capabilities as well as MSD's approach to plant upgrades
to achieve better ammonia treatment. This evaluation should provide a distinct timeline with general
actions to be taken by MSD to aid the Division in understanding the timeline needed for the French Broad
River WRF to most expeditiously achieve compliance with ammonia limitations.
MSD provided a package to the Division on June 26, 2023 which included a narrative description of
troubles experienced at the facility related to their ammonia corrective actions and justification for a 5-
year extension to their ammonia schedule of compliance, their 2015 Ammonia Reduction Evaluation and
their April 2023 Scope of Services with Hazen and Sawyer, for a biological treatment alternatives
evaluation. The Scope of Services indicates a timeline that delivers a final evaluation report by September
2024. In their narrative, MSD explains that HRPT construction was completed in January 2023 but
inconsistent and inefficient operation of the HRPT system has delayed the 2-year performance testing as
required by the existing ammonia schedule of compliance. Additionally, MSD noted that the reduction of
the targeted limits, though more reflective of the outcome of their 2015 Ammonia Reduction Evaluation,
will require additional capital investment for the initial upgrade, and greater O&M costs to run the
system. MSD is of the opinion that this significant change in final effluent quality alone warrants a 5-year
extension to the compliance schedule. Another reason for requesting an extension to the permit schedule
is the sheer complexity of the biological upgrade. MSD's WRF is extremely limited in available space
and will make construction of the new biological treatment process difficult. The upgrade will be
constructed within the confines of the existing plant footprint, so phasing and temporary bypassing will
be required. Maintenance of Plant Operations (MOPO) and effluent compliance during construction will
perhaps be the most challenging aspect of the upgrade.
After further discussion between the Division and MSD, it was determined a more in-depth
implementation plan was required prior, which would provide additional information into the ammonia
treatability strategy for MSD and identify a critical path for achieving compliance with the proposed site -
specific ammonia limits. Hazen and Sawyer prepared a Technical Memorandum: French Broad River
Water Reclamation Facility Implementation Plan on behalf of MSD and MSD submitted the memo to the
Division for review on October 16, 2023. Based on review of the memo's outline of site conditions,
treatment alternatives, and construction/implementation scheduling, and an additional Microsoft Teams
discussion with the Permittee on 11/29/2023, the Division has agreed to extend the ammonia compliance
schedule as follows. Along with the extended schedule, the permit limits have been revised to include
interim limits as milestones throughout the construction schedule at the facility.
The schedule has been adjusted to the following:
Deadline
Milestone
December 31, 2024
Submit annual progress report
Biological Treatment Alternatives Evaluation: Perform initial parts: (a) Preliminary
evaluations; b Process alternatives development; c Process verification and selection
December 31, 2025
Complete HRPT 2-year performance testing; Biological Treatment Alternatives
Evaluation: (a) preliminary evaluations; (b) process alternatives and development; (b)
process verification and selection updates
Page 7 of 14

December 31, 2026
Biological Treatment Alternatives Evaluation: (a) Selected alternative concept
development; b Complete PER and submit to NC DE
December 31, 2027
Biological Treatment Upgrade Project design: (a) Engineer selection; (b) Onsite piloting
and performance verification
December 31, 2028
Pretreatment: (a) identification of Significant Industrial Users (SIUs) sending ammonia to
facility; (b) monitoring of or modification of Industrial User Permits (IUPs) to ensure
sampling of ammonia at identified SIUs
December 31, 2029
Biological Treatment Upgrade Project design: Complete including: (a) All permitting; (b)
ATC submittal and approval; c 100% design / Issued for construction
December 31, 2030
Biological Treatment Upgrade Project construction: (a) Advertise and bid; (b) Contractor
selection and award; c Mobilization
December 31, 2031
Construction in progress; Submit annual progress report
December 31, 2032
Construction in progress; Submit annual progress report
December 31, 2033
Biological Treatment Upgrade Project construction: (a) portion of construction completion
and either: (b) Achieve compliance with interim ammonia monthly average limit of 29.0
mg/L and weekly average limit of 35.0 mg/L or (c) Provide written justification for delay
ammonia reductions including assurance that the construction timeline has been expedited
to achieve compliance with monthly average and weekly average ammonia limits of 23.0
mg/L and 35.0 mg/L, respectively, by December 31, 2024 at the expense of achieving
compliance with limits outlined in item b
December 31, 2034
Construction in progress; Submit annual progress report - if item (c) was satisfied in 2023
milestones, achieve compliance with monthly average and weekly average ammonia limits
of 23.0 mg/L and 35.0 mg/L, respectively.
December 31, 2035
Biological Treatment Upgrade Project construction: (a) additional construction completion;
(b) Achieve compliance with interim ammonia monthly average limit of 23.0 mg/L and
weekly average limit of 35.0 mg/L
December 31, 2036
Construction in progress; Submit annual progress report
December 31, 2037
Biological Treatment Upgrade Project construction: (a) All construction complete; (b)
Achieve compliance with final summer ammonia monthly average limit of 8.5 mg/L and
weekly average limit of 21.4 mg/L and winter ammonia monthly average limit of 17.0
mg/L and weekly average limit of 35.0 mg/L
Reasonable Potential Analysis (RPA) for Toxicants
If applicable, conduct RPA analysis and complete information below.
The need for toxicant limits is based upon a demonstration of reasonable potential to exceed water quality
standards, a statistical evaluation that is conducted during every permit renewal utilizing the most recent
effluent data for each outfall. The RPA is conducted in accordance with 40 CFR 122.44 (d) (i). The NC
RPA procedure utilizes the following: 1) 95% Confidence Level/95% Probability; 2) assumption of zero
background; 3) use of %2 detection limit for "less than" values; and 4) streamflows used for dilution
consideration based on 15A NCAC 2B.0206. Effective April 6, 2016, NC began implementation of
dissolved metals criteria in the RPA process in accordance with guidance titled NPDES Implementation of
Instream Dissolved Metals Standards, dated June 10, 2016.
A reasonable potential analysis was conducted on effluent toxicant data collected between January 2019
and March 2023. Pollutants of concern included toxicants with positive detections and associated water
quality standards/criteria. Based on this analysis, the following permitting actions are proposed for this
permit:
• Effluent Limit with Monitoring. The following parameters will receive a water quality -based
effluent limit (WQBEL) since they demonstrated a reasonable potential to exceed applicable
water quality standards/criteria: None
• Monitoring Only. The following parameters will receive a monitor -only requirement since they
did not demonstrate reasonable potential to exceed applicable water quality standards/criteria,
but the maximum predicted concentration was >50% of the allowable concentration: None
Page 8 of 14

• No Limit or Monitoring: The following parameters will not receive a limit or monitoring, since
they did not demonstrate reasonable potential to exceed applicable water quality
standards/criteria and the maximum predicted concentration was <50% of the allowable
concentration: Total Arsenic, Total Cadmium, Total Beryllium, Total Chromium, Total Copper,
Total Cyanide, Total Lead, Total Nickel, Total Selenium, Total Silver, Total Zinc
• POTW Effluent Pollutant Scan Review: Three effluent pollutant scans were evaluated for
additional pollutants of concern.
o The following parameter(s) will receive a water quality -based effluent limit (WQBEL)
with monitoring, since as part of a limited data set, two samples exceeded the allowable
discharge concentration: None
o The following parameter(s) will receive a monitor -only requirement, since as part of a
limited data set, one sample exceeded the allowable discharge concentration: None
o The following parameters will not receive a limit or monitoring, since they did not
demonstrate reasonable potential to exceed applicable water quality standards/criteria and
the maximum predicted concentration was <50% of the allowable concentration: None
detected
If applicable, attach a spreadsheet of the RPA results as well as a copy of the Dissolved Metals
Implementation Fact Sheet for freshwater/saltwater to this Fact Sheet. Include a printout of the RPA
Dissolved to Total Metal Calculator sheet if this is a Municipality with a Pretreatment Program.
Toxici . Testing Limitations
Permit limits and monitoring requirements for Whole Effluent Toxicity (WET) have been established in
accordance with Division guidance (per WET Memo, 8/2/1999). Per WET guidance, all NPDES permits
issued to Major facilities or any facility discharging "complex" wastewater (contains anything other than
domestic waste) will contain appropriate WET limits and monitoring requirements, with several
exceptions. The State has received prior EPA approval to use an Alternative WET Test Procedure in
NPDES permits, using single concentration screening tests, with multiple dilution follow-up upon a test
failure.
Describe proposed toxicity test requirement: This is a Major POTW, and a chronic WET limit at 12%
effluent will continue on a quarterly frequency.
Mercury Statewide TMDL Evaluation
There is a statewide TMDL for mercury approved by EPA in 2012. The TMDL target was to comply
with EPA's mercury fish tissue criteria (0.3 mg/kg) for human health protection. The TMDL established a
wasteload allocation for point sources of 37 kg/year (81 lb/year), and is applicable to municipals and
industrial facilities with known mercury discharges. Given the small contribution of mercury from point
sources (^ 2% of total load), the TMDL emphasizes mercury minimization plans (MMPs) for point source
control. Municipal facilities > 2 MGD and discharging quantifiable levels of mercury (>1 ng/1) will
receive an MMP requirement. Industrials are evaluated on a case -by -case basis, depending if mercury is a
pollutant of concern. Effluent limits may also be added if annual average effluent concentrations exceed
the WQBEL value (based on the NC WQS of 12 ng/1) and/or if any individual value exceeds a TBEL
value of 47 ng/l.
Table 4. Mercury Effluent Data Summary
2019
2020
2021
2022
2023
# of Samples
4
5
2
1
1
Annual Average Conc. n L
8.5
9.3
22.1
< 0.2
28.2
Maximum Conc., n /L
12.5
10.2
26.1
< 0.2
28.2
TBEL, n /L
47
W BEL, n /L
102.2
Page 9 of 14

Describe proposed permit actions based on mercury evaluation: Since no annual average mercury
concentration exceeded the WQBEL, and no individual mercury sample exceeded the TBEL, no mercury
limit is required. However, since the facility is >2 MGD and reported quantifiable levels of mercury (> 1
ng/1), the mercury minimization plan (MMP) has been maintained.
Other TMDL/Nutrient Management Strategy Considerations
If applicable, describe any other TMDLs/Nutrient Management Strategies and their implementation
within this permit: NA
Other WQBEL Considerations
If applicable, describe any other parameters of concern evaluated for WQBELs: As required by Session
Law 2018-5, Senate Bill 99, Section 13.1(r), every applicant shall submit documentation of any additional
pollutants for which there are certified methods with the permit application if their discharge is
anticipated via a Chemical Addendum to NPDES Application table. As an attachment to the permit
application, MSD provided sampling event data from 2020, 2021 and 2022 for PFAS and 1,4-dioxane.
These samples were taken at the influent fine screen and chlorine contact chamber. EPA Method 537
(Modified) was used for analysis of PFAS. MSD reported detections of various PFAS compounds at their
influent fine screen and chlorine contact chamber during three of the four sampling events. 1,4-dioxane
was not detected in any sampling event. Additionally, MSD provided a chemical addendum (attached)
showing their participation in an ongoing 2023 Swim Season E. Coli Study. Please see Monitoring
Requirements for more information.
If applicable, describe any special actions (HQW or ORW) this receiving stream and classification shall
comply with in order to protect the designated waterbody: NA
If applicable, describe any compliance schedules proposed for this permit renewal in accordance with
15A NCAC 2H 0107(c)(2)(B), 40CFR 122.47, and EPA May 2007 Memo: The current permit includes a
schedule of compliance for effluent ammonia limits that concludes on October 1, 2030. Based on
discussions with MSD and review of their submitted supporting information, an option to submit an
Ammonia Treatment Evaluation Study to justify extension of the schedule of compliance 5 years to
October 1, 2035 has been added. Should no acceptable study be submitted and approved, the October 31,
2030 deadline is maintained. Please see Ammonia and Total Residual Chlorine Limitations for more
information.
If applicable, describe any water quality standards variances proposed in accordance with NCGS 143-
215.3(e) and 15A NCAC 2B.0226 for this permit renewal: NA
7. Technology -Based Effluent Limitations (TBELs)
Municipals (if not applicable, delete and skip to Industrials)
Are concentration limits in the permit at least as stringent as secondary treatment requirements (30 mg/l
BODS/TSS for Monthly Average, and 45 mg/l for BODS/TSS for Weekly Average). YES
If NO, provide a justification for alternative limitations (e.g., waste stabilization pond). NA
Are 85% removal requirements for BODS/TSS included in the permit? YES
If NO, provide a justification (e.g., waste stabilization pond). NA
8. Antidegradation Review (New/Expanding Discharge):
The objective of an antidegradation review is to ensure that a new or increased pollutant loading will not
degrade water quality. Permitting actions for new or expanding discharges require an antidegradation
review in accordance with 15A NCAC 2B.0201. Each applicant for a new/expanding NPDES permit
must document an effort to consider non -discharge alternatives per 15A NCAC 2H.0105(c)(2). In all
cases, existing instream water uses and the level of water quality necessary to protect the existing use is
maintained and protected.
If applicable, describe the results of the antidegradation review, including the Engineering Alternatives
Analysis (EAA) and any water quality modeling results: NA
Page 10 of 14

9. Antibacksliding Review:
Sections 402(o)(2) and 303(d)(4) of the CWA and federal regulations at 40 CFR 122.44(1) prohibit
backsliding of effluent limitations in NPDES permits. These provisions require effluent limitations in a
reissued permit to be as stringent as those in the previous permit, with some exceptions where limitations
may be relaxed (e.g., based on new information, increases in production may warrant less stringent TBEL
limits, or WQBELs may be less stringent based on updated RPA or dilution).
Are any effluent limitations less stringent than previous permit (YES/NO): NO, but schedule of
compliance for ammonia limits may be extended by 5 years to October 31, 2035 if sufficient justification
is submitted to and approved by the Division via an Ammonia Treatment Evaluation Study.
If YES, confirm that antibacksliding provisions are not violated: Justification is to be determined via an
Ammonia Treatment Evaluation Study prepared by an NC Licensed Professional Engineer and approved
by the Division. The evaluation will consider the most expeditious approach to achieving compliance
with the ammonia limits and will provide an updated perspective on the timeline based on existing
setbacks (summarized above in Ammonia and Total Residual Chlorine Limitations) and facility need.
10. Monitoring Requirements
Monitoring frequencies for NPDES permitting are established in accordance with the following
regulations and guidance: 1) State Regulation for Surface Water Monitoring, 15A NCAC 2B.0500; 2)
NPDES Guidance, Monitoring Frequency for Toxic Substances (7/15/2010 Memo); 3) NPDES Guidance,
Reduced Monitoring Frequencies for Facilities with Superior Compliance (10/22/2012 Memo); 4) Best
Professional Judgement (BPJ). Per US EPA (Interim Guidance, 1996), monitoring requirements are not
considered effluent limitations under Section 402(o) of the Clean Water Act, and therefore anti -
backsliding prohibitions would not be triggered by reductions in monitoring frequencies.
For instream monitoring, refer to Section 4.
As MSD identified presence of PFAS in the French Broad River WRF waste stream and the facility is a
major facility discharging 10 miles above the NC/Tenn state border, monitoring of PFAS chemicals will
be added to the permit at a frequency of quarterly. Since an EPA method for sampling and analyzing
PFAS in wastewater is not currently available, the PFAS sampling requirement in the Permit includes a
compliance schedule which delays the effective date of this requirement until the first full calendar
quarter beginning 6 months after EPA has a final wastewater method in 40 CFR136 published in the
Federal Register. This date may be extended upon request and if there are no NC -certified labs.
The EPA 2012 Recreational Water Quality Criteria for Bacterial Indicators of Fecal
Contamination recommends states set bacteriological water quality standards for primary recreation
freshwaters using either the Escherichia coli or Enterococcus pathogenic indicators. North Carolina's
current recreational surface water quality standards for Class B (primary recreation) waters use the fecal
coliform bacteria group pathogenic indicator. The Division sent a letter to MSD on March 8, 2023
requesting participation in a E. coli Study being conducted across the state. This study is being conducted
to evaluate the financial impacts of switching to an E. coli standard for all Class B freshwaters. The data
will inform the Regulatory Fiscal Note a required part of the rulemaking package. The study covers the
2023 Swim Season, April through August, and requires instream and effluent monitoring and reporting of
fecal coliform, E. coli, turbidity, temperature, DO, conductivity and pH. Additionally, instream sampling
events are to be accompanied by a concurrent precipitation recording. MSD has submitted data for April
and May, to date.
The current permit includes Special Condition A.(6.) Groundwater Requirements, which provides detailed
instruction regarding monitoring of 19 parameters and a suite of volatile organic compounds (VOCs)
from four existing groundwater monitoring wells: MW-5, MW-6R, MW-7 and MW-8R. The Permittee
Page 11 of 14

was also required to install four new monitoring wells associated with the Ash Storage Lagoon and the
wastewater treatment system regulator boundary. Upon completion of the new monitoring wells, existing
monitoring wells, MW 1, MW2, MW3, MW4 and two earlier background wells shall be abandoned in
accordance with 15A NCAC 02C .0113. In addition to the monitoring requirements and well
development, the Permittee was required to provide a site map with waste boundaries for the Ash Storage
Lagoon, the location of all property boundaries and the location of each existing and new monitoring
well.
In discussion with the Asheville Regional Office (ARO), it was determined that the four new monitoring
wells have been installed and a site map was provided. As the site map was received, the site mapping
language has been removed from Appendix A. To date, monitoring well MW-1 has been properly
abandoned, but MW-2, MW-3 and MW-4 have not. Language has been added to Appendix A outlining
the requirement for proper closure of MW-2, 3 and 4.
Additionally, the ARO recommended removal of arsenic and silver from the list of groundwater analytes
and addition of nickel and cobalt based on groundwater sampling efforts conducted by ARO. The analyte
list has been revised to reflect this recommendation.
Detailed groundwater monitoring requirements and sampling plan have been included in the attachment
to the permit (See Appendix A). The Permittee shall work directly with DWR Ashville Regional Office
on the sampling plan. If any change is made to the sampling plan, the Permittee shall submit the approved
plan to the Division's NPDES Municipal Permitting Unit.
11. Electronic Reporting Requirements
The US EPA NPDES Electronic Reporting Rule was finalized on December 21, 2015. Effective
December 21, 2016, NPDES regulated facilities are required to submit Discharge Monitoring Reports
(DMRs) electronically. While NPDES regulated facilities would initially be required to submit additional
NPDES reports electronically effective December 21, 2020, EPA extended this deadline from December
21, 2020, to December 21, 2025. The current compliance date, effective January 4, 2021, was extended as
a final regulation change published in the November 2, 2020 Federal Register. This permit contains the
requirements for electronic reporting, consistent with Federal requirements.
12.Summary of Proposed Permitting Actions:
Table 5. Current Permit Conditions and Proposed Changes Outfall 001
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Flow
MA 40.0 MGD
No change
15A NCAC 213.0505
CBOD5
MA 25.0 mg/1
No change
TQBEL. Secondary treatment
WA 40.0 mg/l
standards/40 CFR 133 / 15A
Monitor and report
NCAC 213.0406 - CBOD
Daily
equivalent; Surface Water
Monitoring, 15A NCAC 2B. 0500
NH3-N
Schedule of
Schedule of Compliance with
WQBEL. 2023 WLA — site -
Compliance with
December 31, 2037 deadline
specific ammonia; Permittee
October 1, 2030
and interim limits;
request for extension of
deadline;
compliance schedule and
Final Limits:
Ammonia Treatment Evaluation
Summer:
Summer:
Study; Surface Water Monitoring,
MA 14.0 mg/l
MA 8.5 mg/l
15A NCAC 213. 0500
WA 35.0 mg/1
WA 21.4 mg/1
Winter:
Winter:
MA 31.7 m /l
MA 17.0 m /l
Page 12 of 14

WA 35.0 mg/l
WA 35.0 mg/l
Monitor and report
Monitor and report Daily
Dail
TSS
MA 30 mg/l
No change
TBEL. Secondary treatment
WA 45 mg/l
standards/40 CFR 133 / 15A
Monitor and report
NCAC 2B .0406; Surface Water
Daily
Monitoring, 15A NCAC 2B. 0500
Fecal coliform
MA 200 /100ml
No change
WQBEL. State WQ standard, 15A
WA 400 /100ml
NCAC 2B .0200; Surface Water
Monitor and report
Monitoring, 15A NCAC 2B. 0500
Dail
Temperature
Monitor and Report
No change
Surface Water Monitoring, 15A
Daily
NCAC 2B. 0508
DO
> 5 mg/l
No change
WQBEL. State WQ standard, 15A
Monitor and Report
NCAC 2B .0200; 15A NCAC 02B
Daily
.0500
pH
6-9 SU
No change
WQBEL. State WQ standard, 15A
Monitor and Report
NCAC 2B .0200; 15A NCAC 02B
Daily
.0500
Conductivity
Monitor and Report
No change
Surface Water Monitoring, 15A
Daily
NCAC 2B. 0500
Total Residual
DM 28 ug/L
No change
WQBEL. 2023 WLA. Surface
Chlorine
Monitor and Report
Water Monitoring, 15A NCAC
Daily
2B. 0500
TKN
No requirement
Monitor and Report Quarterly
For calculation of TN
NO2+NO3
No requirement
Monitor and Report Quarterly
For calculation of TN
Total
Monitor and Report
No change
Surface Water Monitoring, 15A
Nitrogen
Quarterly
NCAC 2B. 0500
Total
Monitor and Report
No change
Surface Water Monitoring, 15A
Phosphorus
Quarterly
NCAC 2B. 0500
Total
Quarterly monitoring
No changes
Hardness -dependent dissolved
Hardness
Upstream and in
metals water quality standards
Effluent
approved in 2016
See Special Condition A.(10.)
Evaluation of PFAS contribution:
PFAS
No requirement
PFAS MonitoringRequirements and
pretreatment facility; Discharge
Pretreatment
above NC/TN border
Instream
Monitor and report
Add upstream pH, and
Based on Instream Data Review;
Monitoring
for DO 3/week
upstream and downstream
Class B receiving stream — fecal
during June, July,
fecal coliform and ammonia;
coliform; Site -specific effluent
August and
All instream monitoring
ammonia limitations — upstream
September then once
(except hardness) to be
pH and ammonia; 15A NCAC 02B
per week in the
conducted 3/week during
.0508 — variable sampling
remaining months of
June, July, August and
frequencies
the year and
September then once per
temperature and
week in the remaining months
conductivity daily
of the year
Toxicity Test
Chronic limit, 12%
No change
WQBEL. No toxics in toxic
effluent
amounts. 15A NCAC 2B.0200 and
15A NCAC 2B.0500
Page 13 of 14

Effluent
Three times per
No change; conducted in
40 CFR 122
Pollutant Scan
permit cycle
2024, 2025, 2026
Pretreatment
Special Condition
No change
GWR sites as non -significant IUs
Monitoring
A.(4.) Pretreatment
— explains what a non -significant
Monitoring
IU is
Groundwater
Special Condition
No change; Update Unit
15A NCAC 02L .0200; Agreement
Requirements
A.(6.) Groundwater
name
between the Division and
Requirements
Permittee to include groundwater
sampling plan as attachment to the
permit.
Ash Storage
Special Condition
No change
G.S. 143-215.1(b)
Lagoon
A.(7.) Ash Storage
Lagoon
Mercury
MMP Special
No change; MMP maintained
WQBEL. Consistent with 2012
Minimization
Condition
Statewide Mercury TMDL
Plan (MMP)
Implementation.
Electronic
Electronic Reporting
No change
In accordance with EPA Electronic
Reporting
Special Condition
Reporting Rule 2015.
MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max
13. Public Notice Schedule:
Permit to Public Notice: xx/xx/xxxx
Per 15A NCAC 2H .0109 & .0111, The Division will receive comments for a period of 30 days following
the publication date of the public notice. Any request for a public hearing shall be submitted to the
Director within the 30 days comment period indicating the interest of the party filing such request and the
reasons why a hearing is warranted.
14. NPDES Division Contact
If you have any questions regarding any of the above information or on the attached permit, please
contact Nick Coco at [phone] or via email at nick.cocogdeq.nc.gov.
15. Fact Sheet Addendum (if applicable):
Were there any changes made since the Draft Permit was public noticed (Yes/No): NO
If Yes, list changes and their basis below: NA
16. Fact Sheet Attachments (if applicable):
• RPA Spreadsheet Summary
• NPDES Implementation of Instream Dissolved Metals Standards — Freshwater Standards
• NH3/TRC WLA Calculations
• BOD & TSS Removal Rate Calculations
• Mercury TMDL Calculations
• Monitoring Frequency Reduction Evaluation
• POC Review Form
• WET Testing and Self -Monitoring Summary
• Compliance Inspection Report
• Requested Additional Information
• Chemical Addendum
• Ammonia Implementation Plan
Page 14 of 14

Hazen
October 16, 2023
Technical Memorandum
To: Metropolitan Sewerage District of Buncombe County
From: Hazen and Sawyer
French Broad River Water Reclamation Facility
Implementation Plan
1. Introduction
1.1 Purpose
Metropolitan Sewerage District of Buncombe County (MSD) retained Hazen and Sawyer (Hazen) to
develop an Implementation Plan for the French Broad River Water Reclamation Facility (FBRWRF) to
meet the proposed Ammonia Compliance Schedule following the prior correspondence with the North
Carolina Division of Environmental Quality (NC DEQ). The prior correspondence included MSD's
response letter MSD NPDES Permit Renewal Request (Permit NC0024911) issued on June 26, 2023, and
a meeting with MSD, NC DEQ, and Hazen on August 10', 2023. This Implementation Plan precedes the
upcoming Biological Treatment Alternatives Evaluation for the FBRWRF which will be developed by
Hazen in parallel with the high -rate primary treatment (HRPT) optimization and performance testing
being performed by MSD.
This memorandum presents an implementation schedule to accommodate one of the biological processes
under consideration, noting that the selected/chosen process will be identified and summarized in a
Preliminary Engineering Report (PER) to be submitted to NC DEQ by December 31, 2026.
1.2 Existing Treatment Facilities
The FBRWRF serves communities in Buncombe County and northern Henderson County. The FBRWRF
was commissioned in 1967 as a 25 million gallons per day (mgd) activated solids plant with carbon
oxidation and total suspended solids (TSS) removal. In 1988, the facility was converted to a rotating
biological contactors (RBC) process with an expanded capacity for 40 mgd. The RBCs were retrofitted
into the primary clarifiers, activated solids aeration tanks, and the secondary clarifiers. Subsequent plant
upgrades have been performed as follows:
• 1990 — Installation of intermediate clarifiers with intermediate pumps
• 2013 — Installation of cloth disc filters
• 2019 — Headworks improvements including screening, grit removal, and flow equalization
• 2023 — High -rate primary treatment (HRPT) provided by an Actiflo process
MSD French Broad River Water Reclamation Facility Page 1 of 17
Implementation Plan

Hazen October 16, 2023
The recent headworks improvements and HRPT projects provided an elevated hydraulic profile to enable
construction of deeper process basins and to eliminate intermediate pumping in the future biological
treatment upgrade project. The flow equalization component of the headworks improvements project
provided 4.2 million gallons (MG) of storage volume which serves to mitigate peak flows into the plant
that exceed 65 mgd which will reduce process volume required in the future biological treatment upgrade
project. Figure 1-1 displays the existing process flow diagram.
Cwme Fine Grit Secondary Disc Filter ❑isinfecfim
Screen Screen RernavaI Actiflo'• RBC 1 R9C 2 RBC3 Clarifiers
Figure 1-1: Existing Process Flow Diagram
The existing site facilities and processes are shown in Figure 1-2 on the following page. The figure
demonstrates that there is substantial underground infrastructure (piping, electrical, etc.) in and around the
existing facilities which will require detailed bypass piping to be installed by the contractor during
construction to maintain the existing plant in operation while constructing and commissioning new
process facilities.
MSD French Broad River Water Reclamation Facility Page 2 of 17
Implementation Plan

Hazen
EQUALIZATION
_ _ 5 T_ORAG E &
PUMPING- -
r I
DISK
FILTERS
HRPT-
(ACTIFLO)
RBC 3
RBC z
ti I
HEA6 ORKS
FAC LITY
ti
October 16, 2023
RBC i17V
if INFLUENT t ;
DISINFECTION PUM
SECONDARY
CLARIFIERS
___--
wwFwaraMw.w wwww.ww ww w.rwr -r
�rw�rir r r w .r
Figure 1-2: Existing Site Facilities and Processes
MSD French Broad River Water Reclamation Facility Page 3 of 17
Implementation Plan

Hazen October 16, 2023
1.3 Existing Site Conditions
The FBRWRF site is constrained on all sides and cannot easily be expanded without major rock removal.
Figure 1-3 depicts topography showing the substantial grade adjacent to the site with over 100-foot
elevation gain into the hillsides.
Figure 1-3: Topography of Existing FBRWRF Site
Figure 1-4 depicts a cross section of the FBRWRF site from the original construction drawings, demonstrating the
substantial elevation change into the adjacent hillside.
r 2060
A➢.MWISiRAIlLW
9vn arxe
9L6WR'A%V ur.Lrr
Figure 1-4: Representative Cross Section through the FBRWRF Site
MSD French Broad River Water Reclamation Facility
Implementation Plan
Page 4 of 17

Hazen
October 16, 2023
Figure 1-5 on the following page displays an aerial of the FBRWRF site identifying various site
constraints including rock that encompasses the site on the north and east side, the ash lagoon and
embankment dam located on the east side, Riverside Drive (NC 251) and the French Broad River located
on the west side of site, and the Duke Energy electrical substation on the south side of the site.
1.4 Final Effluent Permit
MSD operates the FBRWRF under the National Pollutant Discharge Elimination System (NPDES) permit
NCO024911 (expired December 31,2022). The permit allows for final effluent discharge to the French
Broad River. Table 1-1 summarizes the expired final effluent permit which indicated a compliance
requirement summer ammonia concentration of 14 mg/L by 2030. A courtesy draft renewal permit was
provided and indicated a lower ammonia requirement of 8.5 mg/L by 2035. Table 1-2 summarizes the
courtesy draft final effluent limits.
Table 1-1: Final Effluent Permit - Expired December 31, 2022
Monthly
Weekly
Minimum
Maximum
Parameter
Average
Average
Flow, mgd
40
-
-
Five-day Carbonaceous Biochemical Oxygen
25
40
--
-
Demand (cBOD5), mg/L
Total Suspended Solids (TSS), mg/L
30
45
-
-
Ammonia (NH3-N), mg/L
14
35
--
-
April - October
NH3-N, mg/L
31.7
35
--
-
November —March
Dissolved Oxygen (DO), mg/L
--
--
5.0
-
Total Residual Chlorine (TRC), pg/L
--
--
--
28
Fecal Coliform, Geometric Mean N/100 mL
200
400
--
-
pH
--
--
6.5
9.0
Table 1-2: Courtesy Draft Renewal Permit
Monthly
Weekly
Minimum
Maximum
Parameter
Average
Average
Flow, mgd
40
--
-
-
Five-day Carbonaceous Biochemical Oxygen
25
40
-
-
Demand (cBOD5), mg/L
Total Suspended Solids (TSS), mg/L
30
45
-
-
Ammonia (NH3-N), mg/L
8.5
21.4
-
-
April - October
NH3-N, mg/L
17
35
--
-
November — March
Dissolved Oxygen (DO), mg/L
--
--
5.0
-
Total Residual Chlorine (TRC), Ng/L
--
--
-
28
Fecal Coliform, Geometric Mean N/100 mL
200
400
-
pH
--
--
6.5
9.0
MSD French Broad River Water Reclamation Facility Page 5 of 17
Implementation Plan

Hazen
i�
NORTH SITE RACK SLOPE
10
Figure 1-5: FBRWRF Aerial View
;� pa
�. _ti
October 16, 2023
r
ND ■,
MSD French Broad River Water Reclamation Facility
Implementation Plan
Page 6 of 17

Hazen October 16, 2023
2. Alternatives Analysis
To meet the proposed limits, it will be necessary for MSD to make major upgrades to the existing
biological process due to the inability of the RBCs to reduce the effluent ammonia to a concentration less
than the proposed draft permit. Six intensification biological processes will be evaluated including
conventional and emerging processes. These processes will be evaluated to leverage and utilize the prior
upgrades at the facility. The following biological processes will be evaluated:
• Aerobic Granular Sludge (AGS)
• Biological Aerated Filter (BAF)
• Integrated Fixed -Film Activated Sludge (IFAS)
• Membrane Aerated Biofilm Reactor (MABR)
• Moving Bed Biofilm Reactor (MBBR)
• Densified Activated Sludge (DAS)
The processes will be evaluated based on the site -specific ammonia limits proposed by NC DEQ in
courtesy draft renewal permit NC0024911. The processes will be further evaluated to provide flexibility
for future effluent nutrient limits in the French Broad River, if determined to be required by NC DEQ.
The FBRWRF site constraints require that the Biological Treatment Upgrades project be implemented
within the existing site to the extent possible. This will require new facilities to be designed and
constructed in phases so that adequate existing facilities and equipment remain in operation during
construction to ensure existing effluent permit limits continue to be met through construction.
2.1 Aerobic Granular Sludge (AGS)
The AquaNereda® process is licensed in North America by Aqua -Aerobic. The process utilizes
proprietary operating strategies and equipment to cultivate and retain Aerobic Granular Sludge (AGS)
granules for the purpose of achieving biological nutrient removal in a sequencing batch reactor (SBR)
configuration. AquaNereda® SBRs operate with three main phases (Fill/Draw, React and Settle) per each
cycle, or batch of wastewater treated. AGS granules retained in the reactor provide differing layers of
microbiological activity, whereas the presence of oxygen and electron acceptors decreases towards the
center of each granule. Figure 2-1:Figure 2-1 provides a process flow diagram of the AquaNereda®
process.
comae Screen Fine Grit Hereda`
Screen Removal Acbfla" AGS ❑isc Filter Disinfection
ow
ram_} !'
Figure 2-1: Aerobic Granular Sludge Process Flow Diagram
MSD French Broad River Water Reclamation Facility Page 7 of 17
Implementation Plan

Hazen October 16, 2023
2.2 Biological Aerated Filter (BAF)
The BAF process combines biological nutrient removal, clarification, and filtration in one biofilm system.
Wastewater flows upward through a submerged aerated media bed. The media increases surface area
allowing for microbiological activity for nitrification. A nozzle and screen system retains the media in the
process and a portion of the treated effluent is stored above the media in a tank to serve as backwash
water. The backwash counter -current flow removes stored solids from the process. Figure 2-2 provides a
process flow diagram of the BAF process.
CMM Fine G711 AEV161 Intermediate Bmiogicel Disc FJler 0-wrifection
Sermon SCfBan fZemWpl
Pumping Aemled Rter
Bxkwash
Backwash
Pumping
Stara-.;
Figure 2-2: Biological Aerated Filter Process Flow Diagram
2.3 Integrated Fixed -Film Activated Sludge (IFAS)
The IFAS process utilizes conventional plug flow activated solids and a biofilm process in one system.
The conventional process contains an aerated bulk liquid with mixed liquor nitrification. Media is added
to the bulk liquid to increase surface area allowing for an intensification of microbiological activity.
Screens retain the media within the aeration tanks while the treated effluent flows to secondary
clarification. Figure 2-3 provides a process flow diagram of the IFAS process.
Coarse Fine Grit WAS Secondary Disc Filter Disinfection
Screen Screen Removal Actifto"
Clarifiers
Figure 2-3: Integrated Fixed -Film Activated Sludge Process Flow Diagram
MSD French Broad River Water Reclamation Facility Page 8 of 17
Implementation Plan

Hazen October 16, 2023
2.4 Membrane Aerated Biofilm Reactor (MABR)
The MABR combines a conventional plug flow activated solids and a biofilm process in one system. The
conventional process contains an unaerated bulk liquid with mixed liquor. Gas permeable membrane
cassettes are submerged in the unaerated bulk liquid. Process air flows through the membranes to form an
aerobic biofilm for nitrification. The unaerated bulk liquid provides conditions for denitrification. The
treated effluent flows to secondary clarification. Figure 2-4 provides a process flow diagram of the
MABR process.
Membrane Seconds Disinfection
Coarse Fine Grit Actiflo'" Aerated Biofilm ❑isc Filler
Screen Screen Removal Reactor Clarifiers
Figure 2-4: Membrane Aerated Biofilm Reactor Process Flow Diagram
2.5 Moving Bed Biofilm Reactor (MBBR)
The MBBR process utilizes submerged aerated media. The media increases surface area to allow
microbiological activity. An aeration grid on the bottom provides oxygen for nitrification and mixing of
the media to promote contact with the wastewater. Screens retain the media within the aeration tanks
while the treated effluent flows to secondary clarification. Figure 2-5 provides a process flow diagram of
the MBBR process.
Coarse Fine Grit
Screen Screen Removal ACt f a" Moving Bed Biofilm Secondary Disc Filter pis nfection
Reactor Clarifiers
OFU FRIM
• l till
Figure 2-5: Moving Bed Biofilm Reactor Process Flow Diagram
2.6 Densified Activated Solids (DAS)
The DAS process utilizes conventional plug flow activated solids process, but with additional process
flexibility which results in improved secondary solids settling thereby allowing the process to be operated
at higher mixed liquor concentrations of 5,000 to 5,500 mg/L. Densification operation assumes mixed
liquor settling characteristics with a 30-minute sludge volume index (SVI3o) ranging from 50 to 70 mL/g,
whereas conventional operation, assuming well -settling mixed liquor, typically has a SV13o ranging from
80 to 120 mL/g.
MSD French Broad River Water Reclamation Facility Page 9 of 17
Implementation Plan

Hazen
October 16, 2023
Densification can be achieved through a combination of external selection of superior settling activated
solids through surface wasting, hydrocyclones, and/or screens and metabolic selection with multi -
compartment selectors. Metabolic selection can be achieved with the installation of the three -pass
anaerobic zones as discussed in the previous alternative. This alternative includes hydrocyclones to
provide physical selection. Figure 2-6 provides a process flow diagram of the DAS process.
Coarse Fine Gnl ❑isrniectlon
Screen Screen Removal Acufo- Anaerobic Anoxic Aembic Secondary Disc Filter
Clarifiers
Figure 2-6: Densified Activated Solids Process Flow Diagram
3. Implementation Schedule
The six biological alternatives that will be evaluated are considered intensification processes given the
site constraints and the requirement that the new infrastructure be constructed within the existing basin
footprint to the extent possible. Many of the biological alternatives are emerging technologies; therefore,
the most conventional process DAS was selected as an example for the development of the
implementation schedule.
Figure 3-1 on the following page provides a summary implementation plan and schedule, detailed in the
following subsections.
3.1 HRPT Optimization Schedule
The HRPT process is currently undergoing optimization with the manufacturer, with optimization to be
completed by end -of -year (EOY) 2023. Once the process is optimized, the HRPT process will undergo
two-year performance testing to be completed by EOY 2025. Performance testing will provide the
following information:
Validate reliable treatment capacity prior to finalizing the PER to ensure that the biological processes
are sized appropriately by confirming predictable COD and TSS removal;
41 Verify solids production from the HRPT process for selection and sizing of solids handling processes.
MSD French Broad River Water Reclamation Facility Page 10 of 17
Implementation Plan

Hazen
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Figure 3-1: Summary Implementation Plan and Schedule [Note: Construction phasing as described in Section 3.4]
iMIS I ;.O K I ?6 V
i
i
October 16, 2023
MSD French Broad River Water Reclamation Facility
Implementation Plan
Page 11 of 17

Hazen October 16, 2023
3.2 Biological Treatment Alternatives Evaluation and PER Schedule
The Biological Treatment Alternatives Evaluation will begin in 2024 and will include the following
phases:
• Preliminary evaluations with process screening and constructability evaluations;
• Process alternatives development to compare biological processes and rank the processes based on
multiple factors including treatment reliability, overall footprint, energy use and operational cost
considerations, capital cost, and construction schedule and maintenance of plant operations during
construction;
• Process verification and selection to include site visits to comparable operating treatment plants with
similar biological processes to those being considered;
• Selected alternative concept development to provide preliminary design of the recommended process
within the existing plant site to confirm constructability and reliable treatment of wastewater through
construction;
• Final preliminary engineering report (PER) development and submittal to NC DEQ, to be completed
by EOY 2026.
3.3 Biological Treatment Upgrade Project Detailed Design
The Biological Treatment Upgrades Project design will be developed based on the completed PER. The
project design phase will include the following phases and steps:
• Develop and issue a request for qualifications (RFQ) for design services with interview period and
selection of design engineer;
• Perform process piloting of the selected process at the FBRWRF site with performance verification to
ensure the biological treatment basins are sized appropriately and that functional controls are
optimized to treat a blended influent flow, i.e., raw influent blended with HRPT effluent;
• Design submittals at 30%, 60%, 90% milestones including detailed phasing plans to implement
project with existing facilities in service;
• Permitting (state, local) including submission of authorization to construct (ATC) to NC DEQ, with
appropriate review times, resubmittals, and approvals;
Finalization of Issued For Construction drawings and specifications, to be completed by EOY 2029.
MSD French Broad River Water Reclamation Facility Page 12 of 17
Implementation Plan

Hazen October 16, 2023
3.4 Biological Treatment Upgrade Project Construction
Construction will include advertisement for bids, contractor selection and award; notice to proceed
(NTP), and a minimum of three phases of construction to maintain treatment and effluent quality through
the project. The example DAS three-phase construction plan is described in the following subsections,
which is expected to be similar for the various process alternatives being evaluated. Constructing the
project in phases will result in gradually improved effluent ammonia concentration as new process
facilities are commissioned and blended with RBC effluent. Figure 3-2 demonstrates the anticipated
combined (blended) effluent ammonia concentration based on the portion of flow treated through the
existing RBCs and the remaining portion treated through a new advanced process. The figure
demonstrates that the new effluent ammonia limit of 8.5 mg/L will be met upon completion of the three-
phase project.
0
0 5 10 15 W 25 " 05 40 45 50 55 50 65 N 75 80 95 90 95 100
x Fw. m Hon iran
—W mW Com°rwd E�IFvxAmi.w� AMy &mna IaN — — Wmmk VAnirt �
Figure 3-2: Construction Combined Final Effluent Ammonia
Figure 3-3 shows the existing flow path through the RBCs at the plant, which will achieve an effluent
ammonia concentration of approximately 25 mg/L based on the plant rated capacity of 40 mgd.
EXISTING PORTION OF FLOW THROUGH EXISTING RBCS;100%
PLANT PORTION OF FLOW THROUGH NEW PROCESS: NIA
COMBINED EFFLUENT AMMONIA = 25 nV (APPROXy
7'
J.
rsliir�m�z❑1 I r ��� -J
Figure 3-3: Existing FBRWRF Flow Path
MSD French Broad River Water Reclamation Facility Page 13 of 17
Implementation Plan

Hazen
October 16, 2023
The example phased construction plan for the DAS process is described as follows with resulting
estimated effluent ammonia concentration at the end of each phase.
Biological Treatment Upgrades Construction —Phase 1 (to be completed by EOY 2033):
■ Advertisement for bids, contractor selection and award, and NTP;
■ Mobilization, major site clearing and grading, rock excavation, and other preliminary work;
■ Demolition of select RBCs, piping, electrical, etc.
■ Construction of new process basins on available site space and within available RBC volume;
■ Construction of new blower building and associated electrical and piping;
■ Installation of flow distribution facilities to operate both existing RBCs and new process basins;
■ Installation of major (gravity) piping to new process basins (through highly congested corridors);
■ Plant electrical upgrades to provide power to new facilities and equipment while maintaining
existing facilities and equipment in operation;
■ Startup and commisioning of new process basins with demonstration and performance
verification;
■ Figure 3-4 demonstrates Phase 1 construction of the example DAS process with an estimated
33% of plant flow treated through the new process and with a resulting blended effluent ammonia
concetration of approximately 17 mg/L based on the plant rated capacity of 40 mgd.
0 PHASE 1 PORTION OF FLOW THROUGH EXISTING RSCs: 67%
PORTION OF FLOW THROUGH NEW PROCESS! 33%
COMBINED EFFLUENT AMMONIA = 17 mgA (APPROx)
I ;111JIl II f1�,�Alll�ii F� 6 '
i` I Ii-[f rifIIUI-Qi_
_ -
Figure 34: FBRWRF Biological Process Upgrade — Phase 1 Construction
MSD French Broad River Water Reclamation Facility Page 14 of 17
Implementation Plan

Hazen
October 16, 2023
Biological Treatment Upgrades Construction —Phase 2 (to be completed by EOY 2035):
■ Demolition of select RBCs, piping, electrical, etc.
■ Construction of new process basins within available RBC volume;
■ Installation of flow distribution facilities to operate both existing RBCs and new process basins;
■ Installation of major (gravity) piping to new process basins (through highly congested corridors);
■ Additional electrical work for new facilities;
■ Startup and commisioning of new process basins with demonstration and performance
verification;
■ Figure 3-5 demonstrates Phase 2 construction of the example DAS process with an estimated
67% of plant flow treated through the new process and with a resulting blended effluent ammonia
concetration of approximately 10 mg/L based on the plant rated capacity of 40 mgd (i.e. capacity
will be available to meet the expired final effluent permit summer ammonia concentration of 14
mg/L).
I — I PHASE 1 PORTION OF FLOW THROUGH E J911NG RSCs: 33%
PHASE 2 PORTION OF FLOW THROUGH NEW PROCESS: 67°%
COMBINED EFFLUENT AMMONIA = I mWI IAPPROX7
�L
_LLLULULLLL
I
Figure 3-5: FBRWRF Biological Process Upgrade — Phase 2 Construction
MSD French Broad River Water Reclamation Facility Page 15 of 17
Implementation Plan

Hazen October 16, 2023
Biological Treatment Upgrades Construction —Phase 3 (to be completed by EOY 2037):
■ Demolition of select RBCs, piping, electrical, etc.
■ Construction of final process facilities and/or modifications to existing facilities to complete
process upgrades volume;
■ Installation of major (gravity) piping to new process basins (through highly congested corridors);
■ Additional electrical work for new facilities;
■ Startup and commisioning of new process basins with demonstration and performance
verification;
■ Figure 3-6 demonstrates Phase 3 construction of the example DAS process with 100% of plant
flow treated through the new process and with a resulting effluent ammonia concetration of less
than 5 mg/L based on the plant rated capacity of 40 mgd (i.e. capacity will be available to meet
the new effluent ammonia limit of 8.5 mg/L).
PHASE 1 PORTION OF FLOW THROUGH EXISTING RBCs: WA
PHASE 2 PORTION OF FLOW THROUGH NEW PROCESS' 100%
COMBINED EFFLUENT AMMONIA = -5 nV
[" PHASE 3
r77
Figure 3-6: FBRWRF Biological Process Upgrade — Phase 3 Construction
3.5 Performance Testing
Each phase of construction includes performance testing to verify the process is optimized and the target
effluent ammonia concentration is being met, as included in the overall schedule.
MSD French Broad River Water Reclamation Facility Page 16 of 17
Implementation Plan

Hazen
4. Ammonia Compliance Schedule Summary
October 16, 2023
Table 4-1 summarizes the annual milestones for the ammonia compliance schedule, noting the following:
Construction of the phased project as will be required at the FBRWRF will extend beyond 2035 to an
estimated final completion date of EOY 2037 due to the significant complexity of this project.
MSD's prior request to NC DEQ to extend the NPDES ammonia compliance schedule from the
current date of October 1, 2030 to December 31, 2035 should provide adequate time for the
FBRWRF to meet the expired final effluent permit summer ammonia concentration of 14 mg/L.
We recommend that MSD request that NC DEQ further extend the NPDES ammonia compliance
schedule to December 31, 2037 to provide adequate time for the FBRWRF to meet the lower summer
ammonia requirement of 8.5 mg/L included in the courtesy draft renewal permit.
Table 4-1: Proposed Ammonia Compliance Schedule
Timeline
Milestone
By December 31, 2023
Complete HRPT optimization and begin 2-year performance testing
By December 31, 2024
Submit annual progress report
Complete HRPT 2-year performance testing;
By December 31, 2025
Biological Treatment Alternatives Evaluation: Perform initial parts: (a) Preliminary
evaluations; (b) Process alternatives development; (c) Process verification and
selection
By December 31, 2026
Biological Treatment Alternatives Evaluation: (a) Selected alternative concept
development; (b) Complete PER and submit to NC DEQ
By December 31, 2027
Biological Treatment Upgrade Project design: (a) Engineer selection; (b) Onsite
piloting and performance verification
By December 31, 2028
Biological Treatment Upgrade Project design: Complete design through 60%
By December 31, 2029
Biological Treatment Upgrade Project design: Complete including: (a) All permitting;
b ATC submittal and approval; c 100 /o design / Issued for construction
By December 31, 2030
Biological Treatment Upgrade Project construction: (a) Advertise and bid; (b)
Contractor selection and award; c Mobilization
By December 31, 2031
Phase 1 construction in progress; Submit annual progress report
By December 31, 2032
Phase 1 construction in progress; Submit annual progress report
By December 31, 2033
Biological Treatment Upgrade Project construction: (a) Phase 1 completion; (b)
Demonstrate blended effluent ammonia concentration of <17 mg/L
By December 31, 2034
Phase 2 construction in progress; Submit annual progress report
By December 31, 2035
Biological Treatment Upgrade Project construction: (a) Phase 2 completion; (b)
Demonstrate blended effluent ammonia concentration of <14 mg/L
By December 31, 2036
Phase 3 construction in progress; Submit annual progress report
By December 31, 2037
Biological Treatment Upgrade Project construction: (a) Phase 3 completion; (b)
Demonstrate blended effluent ammonia concentration of <8.5 mg/L
MSD French Broad River Water Reclamation Facility Page 17 of 17
Implementation Plan

Metropolitan Sewerage District
OF BUNCOMBE COUNTY, NORTH CAROLINA
�00�9 Wbt 4PQ0
P NTY,
June 26, 2023
Nick Coco, P.E.
Engineer III
NPDES Municipal Permitting Unit
NC DEQ / Division of Water Resources / Water Quality Permitting
1617 Mail Service Center
Raleigh, NC 27699-1617
Re: MSD NPDES Permit Renewal Request (Permit NCO024911)
Dear Mr. Coco,
This letter is in response to your April 19, 2023 email and is also a follow up to our March 17, 2023 phone call
regarding MSD's request for a 5-year extension to its NPDES Ammonia Compliance Schedule. The compliance
schedule requires construction of a new biological treatment system by December 31, 2029, and compliance with
effluent ammonia limits (as specified in Section A.(1) of the October 1, 2018 permit) by October 1, 2030. In
addition to these milestones, the schedule also requires major interim capital improvements to be completed with
annual progress reporting. However, due to significant constraints, events beyond our control and real
scheduling issues, we are requesting the 5-year extension.
To date, MSD has met all reporting requirements and has completed two of the required plant improvement
projects, Plant Headworks Improvements and High Rate Primary Treatment (HRPT), totaling $27.9M in capital
expenditures. The HRPT is complete; however, MSD experienced a number of setbacks that delayed
construction and performance testing beyond the dates specified in the Ammonia Compliance Schedule. In
November 2020, a fire at MSD's Water Reclamation Facility (WRF) destroyed a large storage building that
housed equipment dedicated to the HRPT project. Reprocurement of the equipment was lengthy due to supply
chain issues (as a result of the pandemic) and progress on site slowed significantly. The project also
experienced staffing shortages due to pandemic quarantine restrictions that delayed the project further.
HRPT construction was completed in January 2023; however, inconsistent and inefficient operation of the HRPT
system has delayed the 2-year performance testing as required by the Ammonia Compliance Schedule. The
HRPT is still being optimized by the system vendor. Until the process is stabilized and is treating reliably,
performance testing is not viable. HRPT effluent data will heavily influence design of the downstream biological
upgrade so it is imperative that sufficient testing be completed. Proceeding with biological design without fully
vetting influent quality will greatly jeopardize MSD's ability to select an appropriate treatment approach, place a
higher level of risk on ultimate compliance and, in truth, be a waste of public time and money.
As expressed in previous correspondence, MSD is at a critical juncture in the development of the biological
upgrades at its WRF. In accordance with the Ammonia Compliance Schedule, we have recently embarked on a
($600,000) Biological Treatment Alternatives Evaluation Preliminary Engineering Report (PER) to identify the
best technology to accomplish both near term and long-term effluent goals. Our intent is not just to meet the
ammonia limits stipulated in the permit, but to position the WRF to accomplish nutrient removal should it be
required in the future. The PER will provide a well -planned, phased approach to accomplish these tasks.
The scope of the PER is centered around effluent ammonia limits as defined in the 2018 permit. Your April 19,
2023 email suggests that these values may change in the upcoming permit renewal on account of recently
—Protecting Our Natural Resources-
2028 Riverside Drive, Asheville, North Carolina 28804 Telephone: [phone] FAX [phone] Website:www.msdbc.org

conducted site -specific ammonia calculations. A Summer monthly concentration of 8.5mg/L is listed, equating to
a reduction of nearly 40% from the previously targeted limit. This reduction will require additional capital
investment for the initial upgrade, and greater O&M costs to run the system. MSD is of the opinion that this
significant change in final effluent quality alone warrants a 5-year extension to the compliance schedule.
Another reason for requesting an extension to the permit schedule is the sheer complexity of the biological
upgrade. MSD's WRF is extremely limited in available space and will make construction of the new biological
treatment process difficult. The upgrade will be constructed within the confines of the existing plant footprint, so
phasing and temporary bypassing will be required. Maintenance of Plant Operations (MOPO) and effluent
compliance during construction will perhaps be the most challenging aspect of the upgrade. Having spoken with
various qualified consultants, all have agreed the Ammonia Compliance Schedule is extremely tight and perhaps
unattainable given the complexities of the project.
Ammonia and Biological Treatment Evaluations
The email received on April 19, 2023 requested an Ammonia Treatment Evaluation Study be submitted to aid
NCDEQ in understanding the timeline necessary to most expeditiously achieve compliance with the existing
treatment limitations. The evaluation was to identify the WRF's current capabilities as well as MSD's approach to
plant upgrades to achieve better ammonia treatment. The Ammonia Reduction Evaluation, completed in 2015 at
the request of NCDEQ still accurately addresses the WRF's nitrification capabilities and identifies steps and
general actions being taken towards better ammonia removal. The PER being produced now will serve as an
addendum to the Ammonia Reduction Evaluation and will provide clear direction on a specific technology, steps
to be taken, and construction timeline. The PER is scheduled for completion in late 2024; however, an extension
to the completion date is being proposed to better align with HRPT performance testing. Detailed discussion has
been provided below on the Ammonia Reduction Evaluation, Biological Treatment Evaluation PER, and
proposed timeline for achieving ammonia -nitrogen limits.
2015 Ammonia Reduction Evaluation
MSD completed an Ammonia Reduction Evaluation in 2015 to evaluate the feasibility and costs for reducing
ammonia -nitrogen by (1) optimizing the existing plant with operational improvements, and (2) upgrading the plant
to meet proposed summer and winter ammonia limits, as defined in the 2011 NPDES permit. The limits used for
the evaluation closely resemble those recently calculated (i.e. April 2023) for MSD's site -specific discharge. For
this reason, the document remains a valid tool in assessing the WRF's capabilities of meeting proposed
ammonia concentrations. A comparison of the proposed limits, including those in the 2018 permit are shown
below.
Date
Summer
(April 1— Oct. 31)
Winter
(Nov. 1— March 31)
Monthly Avg.
Weekly Avg.
Monthly Avg.
Weekly Avg.
2011 NPDES (Req'd for
Ammonia Reduction Eval.)
6.9 mg/L
20.7 mg/L
17.0 mg/L
35.0 mg/L
2018 NPDES
14.0 mg/L
35.0 mg/L
31.7 mg/L
35.0 mg/L
2023 (Proposed Site Specific)
8.5 mg/L
21.4 mg/L
1 24.7 mg/L
1 61.8 mg/L
The Ammonia Reduction Evaluation described various treatment challenges that impacted performance in the
RBC process and recommended initial upgrades critical to improving, to the degree possible, biological treatment
and addressing the nitrification potential in the RBC process. As reflected in the 2015 report, this approach
would not achieve final limits but would provide some additional improvement in effluent ammonia levels.
The evaluation's recommended initial improvements included replacing failed/idle RBC units, reducing grit and
solids accumulation in the RBCs, reducing organic loading to the RBCs, and managing wet weather flows into
the WRF. These recommendations were to help optimize the RBC system and provide an appropriate treatment
foundation for upgrading biological treatment. Each recommendation is described in further detail below.
—Protecting Our Natural Resources-
2028 Riverside Drive, Asheville, North Carolina 28804 Telephone: [phone] FAX [phone] Website:www.msdbc.org

• Out of Service RBCs
In 2014, thirty-eight (38) of the 152 RBC units were inoperable, removed, or had broken shafts and were
not turning. Without these units in service, the total RBC surface area available for biological treatment
was greatly reduced. MSD underwent an intensive search for replacement RBC units and by 2017 all
inoperable units had been replaced. Since that time, additional units have failed and currently 11 units
are inoperable.
Grit/Solids Accumulation in RBCs
Poor grit removal and lack of primary clarification resulted in the collection of solids and grit throughout
downstream processes. Settled solids in the RBC basins reduce residence time in the biological process
and accumulated solids in the interstices of the RBC units increases operating weight and loads on the
shafts, leading to failure. Additionally, solids and grit increase organic loading to the biological process.
Because nitrification does not occur until most of the organic load has been oxidized, increased solids
and grit loading reduces the likelihood of nitrification occurring in the RBC process.
Two major projects were completed as a result of the evaluation that significantly reduced solids and grit
loading. The first was the Plant Headworks Improvements project, placed online in 2019. This project
included the replacement of existing 1/4" bar screens with'/2" bar screens, installation of new'/4" fine
screens, and new vortex grit removal system. The project has helped reduce solids and grit loading into
the biological process. Headworks performance testing was one of the initial phases of the Ammonia
Compliance Schedule and was completed in 2020.
The second major project was the installation of the HRPT, a chemically -enhanced, high -rate primary
clarification process. Operation of the HRPT facility remains sporadic due to loss of sand ballast during
operation; however, when the process is running, the facility removes >80% TSS and >60% particulate
BOD. Higher levels of treatment are possible with increased coagulant and polymer doses but the goal
of the HRPT is to balance TSS removal rates while maintaining sufficient primary effluent ortho-P and
CBOD to support downstream biological processes. As mentioned above, MSD continues to work with
the HRPT vendor to come up with a permanent operational strategy, one that replicates the successful
results achieved in the 2014 pilot study.
Wet Weather Flows
Surge/flow equalization was recommended as a management strategy for trimming peak flows during
wet weather operations and reducing adverse treatment process impacts such as loss of RBC biofilm
and nitrifier washout. As part of the Plant Headworks Improvements, two (2) out -of -service anaerobic
sludge digester tanks were converted into flow equalization storage. The tanks have a combined volume
of 4.2 MG and are used to mitigate flows into the plant that exceed 65mgd, the design treatment capacity
of the RBCs and other downstream processes. The tanks have been used approximately 6 times since
2019 and have proven successful in managing wet weather peaks and stabilizing flow through the WRF.
The Ammonia Reduction Evaluation also included the assessment of feasible treatment alternatives capable of
meeting the ammonia reduction targets. The short-listed alternatives included Activated Sludge, Moving Bed
Biofilm Reactor (MBBR), Integrated Fixed Film Activated Sludge (IFAS), and Membrane Bioreactor (MBR).
These technologies and others will be evaluated further in the PER.
A copy of the 2015 Ammonia Reduction Evaluation is included with this letter.
2024 Bioloaical Treatment Evaluation PER
The Biological Treatment Evaluation PER will provide prioritized recommendations for the large capital projects
related to biological treatment improvements. As required by the Ammonia Compliance Schedule, the PER will
include a selected technology, specific steps to be taken to achieve ammonia limits, and design and construction
timelines. Phasing recommendations will also be included, along with methods for maintaining plant operations
during construction, and cost estimates. MSD's selected consultant, Hazen & Sawyer will provide the following
services:
Influent wastewater characterization, and future flow and load projections. HRPT performance data is
critical to this step.
—Protecting Our Natural Resources-
2028 Riverside Drive, Asheville, North Carolina 28804 Telephone: [phone] FAX [phone] Website:www.msdbc.org

• Condition assessment of existing plant structures, equipment, and electrical systems.
• Capacity evaluation for future expansion of biological treatment process.
• Technology assessment for future biological treatment processes, including: Densified Activated Sludge
(DAS), Aerobic Granular Sludge (AGS), Moving Bed Biofilm Reactor (MBBR), Biological Aerated Filter
(BAF), Membrane Aerated Biofilm Reactor (MABR), and Integrated Fixed -Film Activated Sludge (IFAS).
• Preliminary permitting for new biological treatment process.
A copy of Hazen & Sawyer's Scope of Services is included with this letter for your review. MSD's Board of
Director's issued approval to begin the PER on May 17, 2023.
Proposed Revisions to Ammonia Compliance Schedule
Timeline
Milestone
Complete HRPT optimization and begin 2-year performance
By December 31, 2023
testing. Continue with Biological Treatment Alternatives
Evaluation.
By December 31, 2025
Complete HRPT 2-year performance testing. Continue with
Biological Treatment Alternatives Evaluation.
By December 31, 2026
Complete Biological Treatment Alternatives Evaluation including
chosen alternative.
By December 31, 2029
Complete Biological Treatment system design and submit
application for ATC.
By December 31, 2034
Complete Biological Treatment system construction and begin
performance testing.
By December 31, 2035
Achieve compliance with the ammonia limits in Section A. (1).
We understand and appreciate that it is critical that MSD move forward diligently and be provided with the
necessary time to do a complete job. The long-term viability and compliance of the upgraded facility depends on
having sufficient time to complete this comprehensive project. We would appreciate a letter agreeing to extend
the schedule to 2035 so that we can move forward in the most effective manner possible
Sincerely,
Thomas E. Hartye
MSD General Manager
Cc:
Gary Perlmutter, NCDEQ
Dan Boss, NCDEQ
Forrest Westall, McGill Assoc.
Hunter Carson, MSD
Bart Farmer, MSD
—Protecting Our Natural Resources-
2028 Riverside Drive, Asheville, North Carolina 28804 Telephone: [phone] FAX [phone] Website:www.msdbc.org

NPDES Chemical Addendum
NPDES No. - NC0024911
Facility Name - French Broad River Water Reclamation Facility
Outfall No. - 001, French Broad River, subbasin 04-03002 [HUC: 0601105]
Pollutant
Method Number
Reason Pollutant Believed
Estimated Concentration
CAS number
(Required)
(if Applicable)
Present in Discharge
(If Known)
TKN
7727-37-9
351.2
30.47 mg/I
E. Coli
Ecolilert
26.78 mpn/100ml
Soluble BOD
5210B
6.51 mg/I
NOx
1 11104-93-1
1 353.2
1
1 1.59 ppm
Notes:
1. Concentrations shown above are averages
2. PFAS & 1-4 Dioxane are not sampled at the effluent

r_

Monthly Avg.
6.9 mg/L
Weekly Avg.
20.7 mg/L
Monthly Avg.
17.0 mg/L
Weekly Avg.
35.0 mg/L
0�
Ammonia Reduction
FINAL

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EXISTING TREATMENT PROCESS FLOW DIAGRAM
Coarse Fine G. RBG I RBC2 RPC 3
:creep Screen Re ql,:)
DISK
FILTERS
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CLA-RIF
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EQUALIZATION
STORAGE &
PUMPING
rl
HEADWORKS
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INFLUENT
PUMP
STATIOI
IEN
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50
45
M
35
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M
30
a
.
a�
25
CD
20
15
5
•
0
Jan-20 Jul-20 Jan-21 Jul-21 Jan-22 Jul-22 Jan-23 Jul-23 Jan-24
• PI Ammonia Conc FNE Ammonia Conc —PI 30-day Mov. Avg —FNE 30-day Mov. Avg.
Inf. vs. EfF. Ammonia Concentrations

•
• SUMMER AVERAGES: MONTHLY - 14.0MG/L, WEEKLY - 35.OMG/L
• WINTER AVERAGES: MONTHLY - 3 1.7MG/L, WEEKLY - 35.OMG/L
• SUMMER AVERAGES: MONTHLY - 8.5MG/L, WEEKLY - 2 1.4MG/L
• WINTER AVERAGES: MONTHLY - 17.0MG/L, WEEKLY - 35.OMG/L
• REVISIONS REQUESTED TO SCHEDULE

ScreenCoarse
- ■ Disinfection
Screen Removal Actiflo'" AGS mediate Biological Disinfection
Screen Screen Removal Pumping Aerated Filter Disc Filter
lop
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akah Bcws
upntrg
Coarse Fin. Grit
Screen Screen Removal Act�flcl. I FAS Secondary Disc Filter Disinfectior.
Membrane Seconds Disinfection
Coarse Fine Grit Acti " Aerated Biofilm Secondary Disc Filter
Screen Screen Removal Reactor Clarifiers
Coarse Fine Grit gctiflo•" Secondary Disinfection
Screen Screen Removal Moving Bed Biofilm Disc Filter
Reactor Clarifiers
Coarse Fine Grit
Screen Screen Removal Actifio•^ Anaerobic Anoxic Aerobic Secondary Disc Filter Disinfection
Clarifiers
e

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2020 2000
Section A -A

NORTH SiTE ROCK SLOPE
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ADJAC L NT RIVER AND ROAD
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rt ter.:.

PHASE 1 PORTION OF FLOW THROUGH EXISTING RBCS: 67%
PORTION OF FLOW THROUGH NEW PROCESS: 33%
MENNEN
Niglio
I
r
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[__..._._.. PHASE 1 PORTION OF FLOW THROUGH EXISTING RBCs: 33%
PHASE 2 PORTION OF FLOW THROUGH NEW PROCESS: 67%
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R s x C H B R o A a R F Y e l! `

PHASE 1
PHASE 2
0 PHASE 3
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PORTION OF FLOW THROUGH NEW PROCESS: 100%
1 i �
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Timeline Comparison
Timeline
Milestones as Proposed by MSD (2023-10-16)
Milestone (As revised hythe State)
Milestone (As suggested by MSD in 2023-11-13 Email)
By December 31, 2023
Complete HRPT optimization and begin 2-year performance testing
Complete HRPT optimization and begin 2-year performance testing
Complete HRPT optimization and begin 2-year performance testing
Submit annual progress report, Biological Treatment Alternatives Evaluation:
Submit annual progress report; Biological Treatment Alternatives Evaluation:
Perform initial parts: (a) Preliminary evaluations; (b) Process alternatives
Perform initial parts: (a) Preliminary evaluations; (b) Process alternatives
By December 31, 2024
Submitannual progress report
development; (c) Processverificatian and selection
development; (c) Proce ss ve rifi cati an and selection
Complete HRPT 2-year performance testing;BiologicaI TreatmentAlternatives
Complete HRPT 2-year performance testing; Biological TreatmentAlternatives
Evaluation: Perform initial parts: (a) Preliminary evaluations; (b) Process
Biological TreatmentAlternatives Evaluation: (a) Selected alternative concept
Evaluation: (a) Selected alternative concept development; (b) Complete PER and
By December 31, 2025
alternatives development; (c) Proce ss ve rifi cati an and selection
development; (b) Complete PER and submit to NC DE4
submit record copy to NC DE4
Biological TreatmentAlternatives Evaluation: (a) Selected alternative concept
Biological Treatment Upgrade Project design: (a) Engineer selection; (b) On site
Biological Treatment Upgrade Project design: (a) Engineer selection; (b) Onsite
By December 31, 2026
development; (b) Complete PER and submit to NC DE4
piloting and performance verification
piloting and performance verification
Biological Treatment Upgrade Project design: Complete including: (a) All
Biological Treatment Upgrade Project design: (a) Engineer selection; (b) On site
permitting; (b) ATC submittal and approval; (c) 100% design / Issued for
By December 31, 2027
piloting and performance verification
construction
Biological Treatment Upgrade Project design: Complete design through 60%
Biological Treatment Upgrade Project design: Complete including: (a) All
Biological Treatment Upgrade Project construction: (a) Advertise and bid; (b)
permitting; (b) ATC submittal and approval; (c) 100% design / Issued for
By December 31, 2028
Biological Treatment Upgrade Project design: Complete design through 60%
Contractor selection and award; (c) Mobilization
construction
Biological Treatment Upgrade Project design: Complete including: (a) All
permitting; (b) ATC submittal and approval; (c) 100% design / Issued for
Biological Treatment Upgrade Project construction: (a) Advertise and bid; (b)
By December 31, 2029
construction
Phase 1 construction in progress; Submit annual progress report
Contractor selection and award; (c) Mobilization
Biological Treatment Upgrade Project construction: (a) Advertise and bid; (b)
By December 31, 2030
Contractor selection and award; (c) Mobilization
Phase 1 construction in progress; Submit annual progress report
Phase 1 construction in progress; Submit annual progress report
Biological Treatment Upgrade Project construction: (a) Phase 1 completion; (b)
Achieve compliance with interim ammonia monthly average limit of 17.0 mg1L and
By December 31, 2031
Phase 1 construction in progress; Submit annual progress report
weekly average limit of 35.0 mg1L
Phase 1 construction in progress; Submit annual progress report
Biological Treatment Upgrade Project construction: (a) Phase 1 completion; (b)
Demonstrate reduction in blended effluent ammonia concentration;submitannual
By December 31, 2032
Phase 1 construction in progress; Submitannual progress report
Phase 2 construction in progress; Submit annual progress report
progress report
Biological Treatment Upgrade Project construction: (a) Phase 2 completion; (b)
Achieve compliance with interim summer ammonia monthly average limit of 10
Biological Treatment Upgrade Project construction: (a) Phase 1 corn pi etion; (b)
mg/L and weekly average limit of 30 mg1L and winter ammonia monthly average
By December 31, 2033
Demonstrate blended effluent ammonia concentration of <17 mg/L
limit of 17.0 mg1L and weekly average limit of 35.0 mg1L
Phase 2construction in progress; Submit annual progress report
Biological Treatment Upgrade Proj ect con stru cti on: (a) Phase 2 completion; (b)
Demonstrate reduction in blended effluent ammonia concentration; submit
By December 31, 2034
Phase 2 construction in progress; Submit annual progress report
Phase 3 construction in progress; Submit annual progress report
annual progress report
Biological Treatment Upgrade Project construction: (a) Phase 3 completion; (b)
Achieve compliance with final summer ammonia monthly average limit of 8.5 mg1L
Biological Treatment Upgrade Project construction: (a) Phase 2 completion; (b)
and weekly average limit of 21.4 mg1L and winter ammonia monthly average limit
By December 31, 2035
Demonstrate blended effluent ammonia concentration of <14 mg1L
of 17.0 mg1L and we e kly ave rage limit of 35.0 mg1L
Phase 3 construction in progress; Submit annual progress report
Biological Treatment Upgrade Proj ect construction: Substantial completion of
By December 31, 2035
Phase 3 construction in progress; Submitannual progress report
I
I Project; (b) Begin Commissioning and Performance Testing
Biological Treatment Upgrade Project construction: (a) Phase 3 completion; (b)
Meet blended effluent ammonia concentration of c8.5 mg1L, submit final project
By December 31, 2037
Demonstrate blended effluent ammonia concentration of c8.5 mg/L
report

Summarized Timeline Comparison
Timeline
Milestones as Proposed by MSD (2423-1416)
Milestone (As revised by the State)
Milestone (As suggested by MSD in 2023-11-13 Email)
By December 31, 2023
Complete HRPT optimization and begin 2-year performance testing
Complete HRPT optimization and begin 2-year performance testing
Complete HRPT optimization and begin 2-year performance testing
By December31,2024
Progress Re port
PER - Year Iof2
PER - Year 1of2
By December al, 2025
HRPT- 2-yr performance Data Compelte
PER - Yea r1of2
PER - Year 2of2,Submit toNCDEQ
HRPT- 2-yr performance Data Compelte
PER - Year 2of2,Submit toNCDEQ
By De ce m ber 31, 2026
PER- Yea r2of2,SubmittoNCDEQ
Engineer Selection and Piloting
Engineer Selection and Piloting
By De ce m ber 31, 2027
En gi nee r Se le ction a nd P i loti ng
Complete 50% Design;
Complete 100% Design;
CompletePermittingincludingATC
Complete 60% Design
By De ce m ber 31, 2028
Complete 60% Design
Adve r tise Project, Se lect Contractor a nd Sta rt Con str ucti o n
Complete 100% Design;
Complete Permitting including ATC
By December 31, 2029
Complete 1004b Design;
Complete Permitting includingATC
Phase 1 construction in progress; Submit annual progress report
Advertise Project, Select Contractor and Start Construction
Phase 1construction in progress; Submit annual progress report
By December 31, 2030
Advertise Project, Select Contractorand Start Construction
Phase Iconstruction in progress; Submit annual progress report
Phase 1Complete
By December 31, 2031
Phase Iconstruction in progress; Submit annual progress report
Phase 1construction in progress; Submit annual progress report
Phase 1Compiete
Phase 2construction in progress; Submit annual progress report
PI
By December 31, 2032
Phase 1 construction in progress; Submit annual progress report
Phase 2 construction in progress; Submit annual progress report
By December 31, 2033
Phase 1 Complete
Phase 2 Complete
By December 31, 2034
Phase 2 construction in progress; Submit annual progress report
Phase 3 construction in progress; Submit annual progress report
Completion of Construction and Meeting Effluent NH3-N limit
By December 31, 2035
Phase
Phase 3 construction in progress; Submit annual progress report
Biological Treatment Upgrade Project construction: Substantial completion of
Project; (b) Begin Com m ission i ng a n d PerformanceTesting
By December 31, 2036
Phase 3 construction in progress; Submit annual progress report
By December 31, 2037
Completion of Construction and Meeting Effluent NH3-N limit
Meet blended effluentammonia concentration of c8.5 mg/L, submit final project
report

Average
21.6 mg/L
Max.
31.9 mg/L
Min.
6.5 mg/L
10'" Perc.
17.4 mg/L
90'" Perc.
26.4 mg/L
Average 18.9 mg/L 21.9 mg/L 24.1 mg/L
Max. 23.9 mg/L 26.5 mg/L 31.9 mg/L
90'" Perc. 21.5 mg/L 25.0 mg/L 28.7 mg/L
mgd
mgd
PF
mgd
PF
24.4
30.7
1.26
67.2
2.75
22.7
29.8
1.31
67.3
2.97
21.2
24.4
1.15
53.7
2.54
22.8
28.3
1.24
62.7
2.75
35
8,000
30
`. 7,000
6,000
25
• '
• ••
♦ «' 5,000
20
.' • •
... • . •
. . •
co
•• ,6 • •
• •
• • • • 4,000
o
.r
. •
•
• •. •
y-
M
L
1cJ
•
• . • •••. .•
• • . ♦
• w .
• . • •
• •
Q�
••• • ••
• •
3,000
0
•
•
U
10
•
2,000
5
•
1,000
0
0
Jan-20 Jul-20 Jan-21 Jul-21
Jan-22 Jul-22 Jan-23 Jul-23 Jan-24
9 PI Ammonia Conc. PI Ammonia Load -30-day Mov. Avg. 30-day Mov. Avg

• SUMMER AVERAGES:
• MONTHLY - 8.5MG/L, WEEKLY - 21.4MG/L
• WINTER AVERAGES:
• MONTHLY - 17.0MG/L, WEEKLY - 35.0MG/L

Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
Table 1. Project Information
❑ CHECK IF HQW OR ORW WQS
Facility Name
French Broad River WRF
WWTP/WTP Class
IV
NPDES Permit
NCO024911
Outfall
001
Flow, Qw (MGD)
40.000
Receiving Stream
French Broad River
HUC Number
06010105
Stream Class
❑ Apply WS Hardness WQC
B
7Q10s (cfs)
466.000
7Q10w (cfs)
595.00
882.00
30Q2 (cfs)
QA (cfs)
2140.00
1 Q10s (cfs)
376.30
Effluent Hardness
52.02 mg/L (Avg)
Upstream Hardness
25 mg/L (Avg)
Combined Hardness Chronic
28.17 mg/L
Combined Hardness Acute
28.82 mg/L
Data Source(s)
Default Upstream T ardness oT 25 mg/L used due 107
average upstream hardness from DMR review being
❑ CHECK TO APPLY MODEL
< 25 mg/L.
REQUIRED DATA ENTRY
Par01
Par02
Par03
Par04
Par05
Par06 E
Par07
Par08
Par09
Par10
Par11
Par12
Par13
Par14
Par15
Par16
Par17
Par18
Par19
Par20
Par21
Par22
Par23
Par24
Table 2. Parameters of Concern
Name WQS Type Chronic Modifier Acute PQL Units
Arsenic
Aquactic Life
C
150
FW
340
ug/L
Arsenic
Human Health
Water Supply
C
10
HH/WS
N/A
ug/L
Beryllium
Aquatic Life
NC
6.5
FW
65
ug/L
Cadmium
Aquatic Life
NC
0.6457
FW
3.6682
ug/L
Chlorides
Aquatic Life
NC
230
FW
mg/L
Chlorinated Phenolic Compounds
Water Supply
NC
1
A
ug/L
Total Phenolic Compounds
Aquatic Life
NC
300
A
ug/L
Chromium III
Aquatic Life
NC
129.8369
FW
1016.9388
ug/L
Chromium VI
Aquatic Life
NC
11
FW
16
pg/L
Chromium, Total
Aquatic Life
NC
N/A
FW
N/A
pg/L
Copper
Aquatic Life
NC
8.7278
FW
11.9743
ug/L
Cyanide
Aquatic Life
NC
5
FW
22
10
ug/L
Fluoride
Aquatic Life
NC
1,800
FW
ug/L
Lead
Aquatic Life
NC
3.3649
FW
88.5870
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5
-,^"
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
41.1919
FW
378.0860
pg/L
Nickel
Water Supply
NC
25.0000
WS
N/A
pg/L
Selenium
Aquatic Life
NC
5
FW
56
ug/L
Silver
Aquatic Life
NC
0.06
FW
0.3786
ug/L
Zinc
Aquatic Life
NC
140.2366
FW
141.8107
ug/L
24911 RPA, input
6/26/2023

REASONABLE POTENTIAL ANALYSIS
H1
H2
Use "PASTE SPECIAL
Effluent Hardness Values" then "COPY"
Maximum data
points = 58
Date
Data
BDL=1/2DL
Results
1
8/6/2019
59.3
59.3
Std Dev. 49.4951
1
2
8/7/2019
64.9
64.9
Mean 52.0224
2
3
9/3/2019
58.6
58.6
C.V. 0.9514
3
4
10/7/2019
59.9
59.9
n 58
4
5
11/5/2019
70.3
70.3
10th Per value 37.70 mg/L
5
6
11/7/2019
66.3
66.3
Average Value 52.02 mg/L
6
7
12/3/2019
53.7
53.7
Max. Value 418.00 mg/L
7
8
1 /9/2020
54.7
54.7
8
9
2/3/2020
37.6
37.6
9
10
2/18/2020
43.6
43.6
10
11
3/9/2020
40.6
40.6
11
12
4/13/2020
58.8
58.8
12
13
5/4/2020
43.5
43.5
13
14
5/14/2020
38.2
38.2
14
15
6/1/2020
42.6
42.6
15
16
7/1/2020
40
40
16
17
8/5/2020
48.7
48.7
17
18
9/29/2020
47.7
47.7
18
19
10/14/2020
41.7
41.7
19
20
11 /2/2020
50.2
50.2
20
21
11 /5/2020
47
47
21
22
12/9/2020
47.3
47.3
22
23
1 /6/2021
418
418
23
24
2/3/2021
43.7
43.7
24
25
3/3/2021
48.2
48.2
25
26
4/7/2021
43.1
43.1
26
27
5/11 /2021
41.9
41.9
27
28
5/26/2021
45
45
28
29
5/27/2021
37.7
37.7
29
30
6/2/2021
43.2
43.2
30
31
7/9/2021
43.1
43.1
31
32
8/2/2021
38.2
38.2
32
33
8/26/2021
44.1
44.1
33
34
9/3/2021
44.9
44.9
34
35
10/1/2021
49.3
49.3
35
36
11 /3/2021
44.4
44.4
36
37
11 /10/2021
45.1
45.1
37
38
12/1/2021
40.7
40.7
38
39
1 /5/2022
44.5
44.5
39
40
2/2/2022
41.6
41.6
40
41
2/10/2022
44.3
44.3
41
42
3/2/2022
42.5
42.5
42
43
4/1/2022
42.4
42.4
43
44
5/4/2022
48.4
48.4
44
45
6/6/2022
40.2
40.2
45
46
7/5/2022
35.6
35.6
46
47
8/4/2022
37.7
37.7
47
48
8/23/2022
37.5
37.5
48
49
9/2/2022
45
45
49
50
10/3/2022
37.5
37.5
50
51
11 /1 /2022
42.5
42.5
51
52
11 /8/2022
41.3
41.3
52
53
12/1/2022
46.1
46.1
53
54
1 /3/2023
34.4
34.4
54
55
2/6/2023
39.8
39.8
55
56
2/9/2023
46.1
46.1
56
57
3/1/2023
45.2
45.2
57
58
4/3/2023
38.9
38.9
58
Upstream Hardness
Date Data BDL=1/2DL Results
Default 25 25 Std Dev.
Mean
C.V.
n
10th Per value
Average Value
Max. Value
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
N/A
25.0000
0.0000
1
25.00 mg/L
25.00 mg/L
25.00 mg/L
24911 RPA, data
- 1 - 6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par01 & Par02
Date
1 2/26/2019
2 2/27/2019
3 5/8/2019
4 5/9/2019
5 8/6/2019
6 8/7/2019
7 11 /5/2019
8 11 /7/2019
9 2/18/2020
10 5/14/2020
11 6/3/2020
12 8/5/2020
13 11 /5/2020
14 5/11 /2021
15 5/27/2021
16 8/26/2021
17 11 /10/2021
18 2/10/2022
19 5/11/2022
20 8/23/2022
21 11 /8/2022
22 2/9/2023
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Arsenic
Data
BDL=1/2DL
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
10
5
<
1
0.5
<
5
2.5
<
25
12.5
<
50
25
Results
Std Dev
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
4.6988
5.9318
0.7921
22
1.42
25.0 ug/L
35.5 ug/L
-2-
24911 RPA, data
6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par03
Date Data
1 2/26/2019 <
2 2/27/2019 <
3 5/8/2019 <
4 5/9/2019 <
5 8/6/2019 <
6 8/7/2019 <
7 11 /5/2019 <
8 11 /7/2019 <
9 2/18/2020 <
10 5/14/2020 <
11 6/3/2020 <
12 8/5/2020 <
13 11 /5/2020 <
14 5/11 /2021 <
15 5/27/2021 <
16 8/26/2021 <
17 11/10/2021 <
18 2/10/2022 <
19 5/4/2022 <
20 5/11 /2022 <
21 2/9/2023 <
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Beryllium
BDL=1/2DL
Results
1 0.5
Std Dev.
1 0.5
Mean
1 0.5
C.V.
1 0.5
n
1 0.5
1 0.5
Mult Factor =
1 0.5
Max. Value
1 0.5
Max. Pred Cw
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
1 0.5
5 2.5
P a r04
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
0.4364
0.5952
0.7332
21
1.42
2.50 ug/L
3.55 ug/L
Date Data
1 2/26/2019 <
2 2/27/2019 <
3 5/8/2019 <
4 5/9/2019 <
5 8/6/2019 <
6 8/7/2019 <
7 11 /5/2019 <
8 11 /7/2019 <
9 2/18/2020 <
10 5/14/2020 <
11 6/3/2020 <
12 8/5/2020 <
13 11 /5/2020 <
14 5/11/2021 <
15 5/27/2021 <
16 8/26/2021 <
17 11/10/2021 <
18 2/10/2022 <
19 5/4/2022 <
20 5/11/2022 <
21 11 /8/2022 <
22 2/9/2023 <
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Cadmium
BDL=1/2DL
Results
1
0.5
Std Dev.
1
0.5
Mean
1
0.5
C.V.
1
0.5
n
1
0.5
1
0.5
Mult Factor =
1
0.5
Max. Value
1
0.5
Max. Pred Cw
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
1
0.5
2.5
1.25
5
2.5
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
0.4482
0.6250
0.7171
22
1.38
2.500 ug/L
3.450 ug/L
-3-
24911 RPA, data
6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par10
Date Data
1 2/26/2019 <
2 2/27/2019 <
3 5/8/2019 <
4 5/9/2019 <
5 8/6/2019 <
6 8/7/2019 <
7 11 /5/2019 <
8 11 /7/2019 <
9 2/18/2020 <
10 5/14/2020 <
11 6/3/2020 <
12 8/5/2020
13 11 /5/2020 <
14 5/11 /2021 <
15 5/27/2021 <
16 8/26/2021 <
17 11/10/2021 <
18 2/10/2022 <
19 5/4/2022 <
20 5/11 /2022 <
21 8/23/2022 <
22 11 /8/2022 <
23 2/9/2023 <
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Chromium, Total
BDL=1/2DL
Results
5
2.5
Std Dev.
5
2.5
Mean
5
2.5
C.V.
5
2.5
n
5
2.5
5
2.5
Mult Factor =
5
2.5
Max. Value
5
2.5
Max. Pred Cw
5
2.5
5
2.5
5
2.5
7
7
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
25
12.5
50
25
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
5.0766
4.1087
1.2356
23
1.59
25.0 pg/L
39.8 dig/L
Pal
Copper
Date
Data
BDL=1/2DL
Results
1
2/26/2019
7.4
7.4
Std Dev.
2
2/27/2019
7.3
7.3
Mean
3
5/8/2019
11
11
C.V.
4
5/9/2019
9
9
n
5
8/6/2019
8.4
8.4
6
8/7/2019
9.7
9.7
Mult Factor =
7
11/5/2019
7.3
7.3
Max. Value
8
11/7/2019
8
8
Max. Pred Cw
9
2/18/2020
7.2
7.2
10
5/14/2020
8.6
8.6
11
6/3/2020
7.2
7.2
12
8/5/2020
7.3
7.3
13
11 /5/2020
7.9
7.9
14
5/11/2021
13.3
13.3
15
5/27/2021
9.6
9.6
16
8/26/2021
8
8
17
11 /10/2021
11
11
18
2/10/2022
8.8
8.8
19
5/4/2022
13.7
13.7
20
5/11/2022
8.6
8.6
21
8/23/2022
7.1
7.1
22
11 /8/2022
< 25
12.5
23
2/9/2023
< 50
25
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
3.8760
9.7348
0.3982
23
1.20
25.00 ug/L
30.00 ug/L
24911 RPA, data
-4- 6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par12
Date Data
1 2/26/2019 <
2 2/27/2019 <
3 8/6/2019 <
4 8/7/2019 <
5 11 /5/2019 <
6 11 /7/2019 <
7 2/18/2020 <
8 5/14/2020 <
9 6/3/2020 <
10 8/5/2020 <
11 11 /5/2020 <
12 5/11/2021 <
13 5/27/2021 <
14 8/26/2021 <
15 11/10/2021 <
16 2/10/2022 <
17 5/4/2022 <
18 11 /8/2022 <
19 2/9/2023 <
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Cyanide
BDL=1/2DL
Results
8
5
Std Dev.
8
5
Mean
8
5
C.V.
8
5
n
8
5
8
5
Mult Factor =
8
5
Max. Value
8
5
Max. Pred Cw
8.0
5
8.0
5
8
5
8
5
8
5
8
5
8
5
8
5
8
5
8
5
8
5
Par14
Use "PASTE SPECIAL
Values" then "COPY"
Maximum data
points = 58
0.0000
5.00
0.0000
19
1.00
5.0 ug/L
5.0 ug/L
Date
1 2/26/2019 <
2 2/27/2019 <
3 5/8/2019 <
4 5/9/2019 <
5 8/6/2019 <
6 8/7/2019 <
7 11 /5/2019 <
8 11 /7/2019 <
9 2/18/2020 <
10 5/14/2020 <
11 6/3/2020 <
12 8/5/2020 <
13 11 /5/2020 <
14 5/11/2021 <
15 5/27/2021 <
16 8/26/2021 <
17 11/10/2021 <
18 2/10/2022 <
19 5/4/2022 <
20 5/11/2022 <
21 8/23/2022 <
22 11 /8/2022 <
23 2/9/2023 <
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Use "PASTE SPECIAL
Lead Values" then "COPY"
Maximum data
points = 58
BDL=1/2DL
Results
5
2.5
Std Dev.
5
2.5
Mean
5
2.5
C.V.
5
2.5
n
5
2.5
5
2.5
Mult Factor =
5
2.5
Max. Value
5
2.5
Max. Pred Cw
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
5
2.5
1
0.5
5
2.5
10
5
0.6822
2.5217
0.2705
23
1.14
5.000 ug/L
5.700 ug/L
-5-
24911 RPA, data
6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par17 & Par18
Nickel
use "PASTE
SPECIAL -
Values" then
Par19
"COPY".
Maximum data
Date
Data
BDL=1/2DL
Results
points = 58
Date
Data
1
2/26/2019
<
5
2.5
Std Dev.
5.0314
1
2/26/2019
<
2
2/27/2019
<
5
2.5
Mean
4.5543
2
2/27/2019
<
3
5/8/2019
<
5
2.5
C.V.
1.1048
3
5/8/2019
<
4
5/9/2019
<
6.3
3.15
n
23
4
5/9/2019
<
5
8/6/2019
<
5.3
2.65
5
8/6/2019
<
6
8/7/2019
<
5
2.5
Mult Factor =
1.54
6
8/7/2019
<
7
11/5/2019
<
6.7
3.35
Max. Value
25.0 pg/L
7
11/5/2019
<
8
11/7/2019
<
5.7
2.85
Max. Pred Cw
38.5 dig/L
8
11/7/2019
<
9
2/18/2020
<
5
2.5
9
2/18/2020
<
10
5/14/2020
<
5
2.5
10
5/14/2020
<
11
6/3/2020
<
9.5
4.75
11
6/3/2020
<
12
8/5/2020
<
7.9
3.95
12
8/5/2020
<
13
11 /5/2020
<
5
2.5
13
11 /5/2020
<
14
5/11 /2021
<
5
2.5
14
5/11 /2021
<
15
5/27/2021
<
5
2.5
15
5/27/2021
<
16
8/26/2021
<
6.7
3.35
16
8/26/2021
<
17
11/10/2021
<
17
8.5
17
11/10/2021
<
18
2/10/2022
<
8
4
18
2/10/2022
<
19
5/4/2022
<
5.3
2.65
19
5/4/2022
<
20
5/11 /2022
<
6.1
3.05
20
5/11 /2022
<
21
8/23/2022
<
5
2.5
21
8/23/2022
<
22
11 /8/2022
<
25
12.5
22
11 /8/2022
<
23
2/9/2023
<
50
25
23
24
24
25
25
26
26
27
27
28
28
29
29
30
30
31
31
32
32
33
33
34
34
35
35
36
36
37
37
38
38
39
39
40
40
41
41
42
42
43
43
44
44
45
45
46
46
47
47
48
48
49
49
50
50
51
51
52
52
53
53
54
54
55
55
56
56
57
57
58
58
Selenium
BDL=1/2DL
Results
10
5
Std Dev.
10
5
Mean
10
5
C.V.
10
5
n
10
5
10
5
Mult Factor =
10
5
Max. Value
10
5
Max. Pred Cw
10
5
10
5
10
5
10
5
10
5
10
5
10
5
10
5
10
5
10
5
10
5
10
5
5
2.5
25
12.5
Use "PASTE SPECIAL -
Values" then "COPY".
Maximum data points
= 58
1.7094
5.2273
0.3270
22
1.17
12.5 ug/L
14.6 ug/L
24911 RPA, data
6/26/2023

REASONABLE POTENTIAL ANALYSIS
Par20
Date Data
1 2/26/2019 <
2 2/27/2019 <
3 5/8/2019 <
4 5/9/2019 <
5 8/6/2019 <
6 8/7/2019 <
7 11 /5/2019 <
8 11 /7/2019 <
9 2/18/2020 <
10 5/14/2020 <
11 6/3/2020 <
12 8/5/2020 <
13 11 /5/2020 <
14 5/11 /2021 <
15 5/27/2021 <
16 8/26/2021 <
17 11/10/2021 <
18 2/10/2022 <
19 5/4/2022 <
20 5/11 /2022 <
21 8/23/2022 <
22 11 /8/2022 <
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Par21
Use "PASTE SPECIAL
Silver Values" then "COPY"
Maximum data
points = 58
BDL=1/2DL
Results
5
2.5
Std Dev.
5
2.5
Mean
5
2.5
C.V.
5
2.5
n
5
2.5
5
2.5
Mult Factor =
0.4
0.2
Max. Value
0.4
0.2
Max. Pred Cw
2
1
5
2.5
0.5
0.25
2
1
0.4
0.2
0.4
0.2
0.4
0.2
0.4
0.2
0.4
0.2
0.4
0.2
0.4
0.2
0.4
0.2
5
2.5
0.4
0.2
1.0983
1.1114
0.9882
22
1.52
2.500 ug/L
3.800 ug/L
Date
1 2/26/2019
2 2/27/2019
3 5/8/2019
4 5/9/2019
5 8/6/2019
6 8/7/2019
7 11 /5/2019
8 11 /7/2019
9 2/18/2020
10 5/14/2020
11 6/3/2020
12 8/5/2020
13 11 /5/2020
14 5/11/2021
15 5/27/2021
16 8/26/2021
17 11 /10/2021
18 2/10/2022
19 5/4/2022
20 5/11/2022
21 8/23/2022
22 11 /8/2022
23 2/9/2023
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
Zinc
Data
BDL=1/2DL
Results
42
42
Std Dev.
89
89
Mean
61
61
C.V.
75
75
n
41
41
43
43
Mult Factor =
37
37
Max. Value
45
45
Max. Pred Cw
42
42
39.1
39.1
41
41
43
43
41
41
52
52
42
42
41
41
68
68
42
42
64
64
39
39
37.2
37.2
53.3
53.3
< 100
50
Use "PASTE SPECIAL -
Values" then "COPY"
Maximum data
points = 58
13.5776
49.0261
0.2769
23
1.14
89.0 ug/L
101.5 ug/L
-7-
24911 RPA, data
6/26/2023

French Broad River WRF
NCO024911 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM DATA POINTS = 58
Qw (MGD) =
40.0000
1Q10S (cfs) =
376.30
7Q I OS (cfs) =
466.00
7Q10W (cfs) =
595.00
30Q2 (cfs) =
882.00
Avg. Stream Flow, QA (cfs) =
2140.00
Receiving Stream:
French Broad River HUC 06010105
WWTP/WTP Class: IV
IWC% @ 1Q10S =
14.1455624
IWC% @ 7Q10S =
11.74242424
IWC% @ 7Q10W -
9.436834094
IWC/o @ 30Q2 =
6.56779661
IW%C @ QA =
2.815622162
Stream Class: B
Outfall 001
Qw=40 MGD
COMBINED HARDNESS (mg/L)
Acute = 28.82 mg/L
Chronic = 28.17 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
co
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
J
Aplied
Chronic Acute
n # Det. Max Pred Cw Allowable Cw
Standa d
Acute (FW): 2,403.6
Arsenic
C
150 FW(7Q10s) 340
ug/L
22 0
35.5
Chronic (FW):--- 1,277.4 -
-----------------------------
Ma_x MDL
Arsenic
C
10 HH/WS(Qavg)
ug/L
NO DETECTS
_=50____
Chronic (HH): 355.2
No RP, Predicted Max < 50% of Allowable Cw - No
Max MDL 50
Monitoring required
Acute: 459.51
Beryllium
NC
6.5 FW(7Q10s) 65
ug/L
21 0
3.55
-----------------------------
Chronic----- 55.35--
NO DETECTS
Max MDL = 5
Acute: 25.932
Cadmium
NC
0.6457 FW(7Q10s) 3.6682
ug/L
22 0
3.450
Chronic: 5.499
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL = 5
Monitoring required
Acute: 7,189.1
Chromium III
NC
129.84 FW(7Q10s) 1016.94
µg/L
0 0
N/A
Chronic: 1,105.7
Acute: 113.1
Chromium VI
NC
11 FW(7Q10s) 16
µg/L
0 0
N/A
[- Chronic: 93.7
Tot Cr value(s) > 5 but < Cr VI Allowable Cw
a: No monitoring required if all Total Chromium
Chromium, Total
NC
µg/L
23 1 39.8 Max reported value 25
samples are < 5 pg/L or Pred. max for Total Cr is <
allowable Cw for Cr VI.
Acute: 84.65
Copper
NC
8.7278 FW(7Q10s) 11.9743
ug/L
23 21
30.00
_
Chronic 74.33
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 155.5
Cyanide
NC
5 FW(701 Os) 22
10
ua/L
19 0
5.0
-----------------------------
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL - 10
Monitoring required
Acute: 626.253
Lead
NC
3.3649 FW(7Q 1 Os) 88.5870
ug/L
23 0
5.700
_
Chronic 28.656
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL = 10
Monitoring required
24911 RPA, rpa
Page 1 of 2 6/26/2023

French Broad River WRF
Outfall 001
NCO024911
Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
Qw=40 MGD
Acute (FW): 2,672.8
Nickel
NC
41.1919 FW(7Q10s) 378.0860
µg/L
23 0
38.5
Chronic (FW): 350.8
No RP, Predicted Max < 50% of Allowable Cw - No
Max MDL = 50
Monitoring required
Nickel
NC
25.0000 WS(7Q10s)
µg/L
NO DETECTS
Chronic (WS): 212.9
Max MDL 50
Acute: 395.9
Selenium
NC
5 FW(7Q10s) 56
ug/L
22 0
14.6
Chronic: 42.6
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL 25
Monitoring required
Acute: 2.676
Silver
NC
0.06 FW(7Q10s) 0.3786
ug/L
22 0
3.800
Chronic: 0.511
All values non -detect < 5 ug/L, < 2 ug/L and < 0.4
ug/L - No Monitoring required; Permittee shall use
NO DETECTS
Max MDL 5
sufficiently sensitive test methods
Acute: 1,002.5
No RP, Predicted Max < 50% of Allowable Cw - No
Zinc
NC
140.2366 FW(7Q10s) 141.8107
ug/L
23 22
101.5
Monitoring required
---- -- -
Chronic: 1,
-----------------------------
No value > Allowable Cw
24911 RPA, rpa
Page 2 of 2 6/26/2023

Permit No. NCO024911
NPDES Implementation of Instream Dissolved Metals Standards - Freshwater Standards
The NC 2007-2015 Water Quality Standard (WQS) Triennial Review was approved by the NC
Environmental Management Commission (EMC) on November 13, 2014. The US EPA subsequently
approved the WQS revisions on April 6, 2016, with some exceptions. Therefore, metal limits in draft
permits out to public notice after April 6, 2016 must be calculated to protect the new standards - as
approved.
Table 1. NC Dissolved Metals Water Q ality Standards/A uatic Life Protection
Parameter
Acute FW, µg/l
(Dissolved)
Chronic FW, µg/l
(Dissolved)
Acute SW, µg/1
(Dissolved)
Chronic SW, µg/1
(Dissolved)
Arsenic
340
150
69
36
Beryllium
65
6.5
---
---
Cadmium
Calculation
Calculation
40
8.8
Chromium III
Calculation
Calculation
---
---
Chromium VI
16
11
1100
50
Copper
Calculation
Calculation
4.8
3.1
Lead
Calculation
Calculation
210
8.1
Nickel
Calculation
Calculation
74
8.2
Silver
Calculation
0.06
1.9
0.1
Zinc
Calculation
Calculation
90
81
Table 1 Notes:
1. FW= Freshwater, SW= Saltwater
2. Calculation = Hardness dependent standard
3. Only the aquatic life standards listed above are expressed in dissolved form. Aquatic life
standards for Mercury and selenium are still expressed as Total Recoverable Metals due to
bioaccumulative concerns (as are all human health standards for all metals). It is still necessary
to evaluate total recoverable aquatic life and human health standards listed in 15A NCAC
2B.0200 (e.g., arsenic at 10 µg/1 for human health protection; cyanide at 5 µg/L and fluoride at
1.8 mg/L for aquatic life protection).
Table 2. Dissolved Freshwater Standards for Hardness -Dependent Metals
The Water Effects Ratio (WER) is equal to one unless determined otherwise under 15A
NCAC 02B .0211 Subparagraph (11)(d)
Metal
NC Dissolved Standard, µg/I
Cadmium, Acute
WER* {1. 136672-[ln hardness](0.041838)} e^10.9151 [ln hardness]-3.1485}
Cadmium, Acute Trout waters
WER* {1. 136672-[ln hardness](0.041838)} e^{0.9151[In hardness]-3.62361
Cadmium, Chronic
WER*{1.101672-[ln hardness](0.041838)} • e^{0.7998[ln hardness] -4.445 11
Chromium III, Acute
WER*0.316 e^{0.8190[ln hardness]+3.7256}
Chromium III, Chronic
WER*0.860 e^{0.8190[ln hardness]+0.6848}
Copper, Acute
WER*0.960 e^{0.9422[ln hardness]-1.700}
Copper, Chronic
WER*0.960 e^{0.8545[ln hardness]-1.702}
Lead, Acute
WER*{1.46203-[ln hardness](0.145712)} • e^{1.273[ln hardness]-1.460}
Lead, Chronic
WER*{1.46203-[ln hardness](0.145712)} • e^{1.273[ln hardness]-4.705)
Nickel, Acute
WER*0.998 e^{0.8460[ln hardness]+2.255}
Nickel, Chronic
WER*0.997 e^{0.8460[ln hardness]+0.0584}
Page 1 of 4

Permit No. NCO024911
Silver, Acute
WER*0.85 • e"O.72[ln hardness]-6.59}
Silver, Chronic
Not applicable
Zinc, Acute
WER*0.978 e^{0.8473[ln hardness]+0.884}
Zinc, Chronic
WER*0.986 e^{0.8473[ln hardness]+0.884}
General Information on the Reasonable Potential Analysis (RPA)
The RPA process itself did not change as the result of the new metals standards. However, application of
the dissolved and hardness -dependent standards requires additional consideration in order to establish the
numeric standard for each metal of concern of each individual discharge.
The hardness -based standards require some knowledge of the effluent and instream (upstream) hardness
and so must be calculated case -by -case for each discharge.
Metals limits must be expressed as `total recoverable' metals in accordance with 40 CFR 122.45(c). The
discharge -specific standards must be converted to the equivalent total values for use in the RPA
calculations. We will generally rely on default translator values developed for each metal (more on that
below), but it is also possible to consider case -specific translators developed in accordance with
established methodology.
RPA Permitting Guidance/WOBELs for Hardness -Dependent Metals - Freshwater
The RPA is designed to predict the maximum likely effluent concentrations for each metal of concern,
based on recent effluent data, and calculate the allowable effluent concentrations, based on applicable
standards and the critical low -flow values for the receiving stream.
If the maximum predicted value is greater than the maximum allowed value (chronic or acute), the
discharge has reasonable potential to exceed the standard, which warrants a permit limit in most cases. If
monitoring for a particular pollutant indicates that the pollutant is not present (i.e. consistently below
detection level), then the Division may remove the monitoring requirement in the reissued permit.
To perform a RPA on the Freshwater hardness -dependent metals the Permit Writer compiles the
following information:
• Critical low flow of the receiving stream, 7Q10 (the spreadsheet automatically calculates
the 1 Q 10 using the formula 1 Q 10 = 0.843 (s7Q 10, cfs) 0.993
• Effluent hardness and upstream hardness, site -specific data is preferred
• Permitted flow
• Receiving stream classification
2. In order to establish the numeric standard for each hardness -dependent metal of concern and for
each individual discharge, the Permit Writer must first determine what effluent and instream
(upstream) hardness values to use in the equations.
The permit writer reviews DMR's, Effluent Pollutant Scans, and Toxicity Test results for any
hardness data and contacts the Permittee to see if any additional data is available for instream
hardness values, upstream of the discharge.
If no hardness data is available, the permit writer may choose to do an initial evaluation using a
default hardness of 25 mg/L (CaCO3 or (Ca + Mg)). Minimum and maximum limits on the
hardness value used for water quality calculations are 25 mg/L and 400 mg/L, respectively.
If the use of a default hardness value results in a hardness -dependent metal showing reasonable
potential, the permit writer contacts the Permittee and requests 5 site -specific effluent and
upstream hardness samples over a period of one week. The RPA is rerun using the new data.
Page 2 of 4

Permit No. NCO024911
The overall hardness value used in the water quality calculations is calculated as follows:
Combined Hardness (chronic)
_ (Permitted Flow, cfs *Avg. Effluent Hardness, mg/L)+s7Q10, cfs *Avg. Upstream Hardness, mg/L)
(Permitted Flow, cfs + s7Q 10, cfs)
The Combined Hardness for acute is the same but the calculation uses the IQ 10 flow.
3. The permit writer converts the numeric standard for each metal of concern to a total recoverable
metal, using the EPA Default Partition Coefficients (DPCs) or site -specific translators, if any
have been developed using federally approved methodology.
EPA default partition coefficients or the "Fraction Dissolved" converts the value for
dissolved metal at laboratory conditions to total recoverable metal at in -stream
ambient conditions. This factor is calculated using the linear partition coefficients
found in The Metals Translator: Guidance for Calculating a Total Recoverable
Permit Limit from a Dissolved Criterion (EPA 823-B-96-007, June 1996) and the
equation:
Cdiss = 1
Ctotal I + { [Kp.] [ss('+a)] [10 6] }
Where:
ss = in -stream suspended solids concentration [mg/1], minimum of 10 mg/L used,
and
Kpo and a = constants that express the equilibrium relationship between dissolved
and adsorbed forms of metals. A list of constants used for each hardness -dependent
metal can also be found in the RPA program under a sheet labeled DPCs.
4. The numeric standard for each metal of concern is divided by the default partition coefficient (or
site -specific translator) to obtain a Total Recoverable Metal at ambient conditions.
In some cases, where an EPA default partition coefficient translator does not exist (ie. silver), the
dissolved numeric standard for each metal of concern is divided by the EPA conversion factor to
obtain a Total Recoverable Metal at ambient conditions. This method presumes that the metal is
dissolved to the same extent as it was during EPA's criteria development for metals. For more
information on conversion factors see the June, 1996 EPA Translator Guidance Document.
5. The RPA spreadsheet uses a mass balance equation to determine the total allowable concentration
(permit limits) for each pollutant using the following equation:
Ca = (s7Q 10 + Qw) (Cwgs) — (s7Q10) (Cb)
Qw
Where: Ca = allowable effluent concentration (µg/L or mg/L)
Cwqs = NC Water Quality Standard or federal criteria (µg/L or mg/L)
Cb = background concentration: assume zero for all toxicants except NH3* (µg/L or mg/L)
Qw = permitted effluent flow (cfs, match s7Q 10)
s7Q 10 = summer low flow used to protect aquatic life from chronic toxicity and human
health through the consumption of water, fish, and shellfish from noncarcinogens (cfs)
* Discussions are on -going with EPA on how best to address background concentrations
Flows other than s7Q 10 may be incorporated as applicable:
IQ 10 = used in the equation to protect aquatic life from acute toxicity
Page 3 of 4

Permit No. NC0024911
QA = used in the equation to protect human health through the consumption of water,
fish, and shellfish from carcinogens
30Q2 = used in the equation to protect aesthetic quality
6. The permit writer enters the most recent 2-3 years of effluent data for each pollutant of concern.
Data entered must have been taken within four and one-half years prior to the date of the permit
application (40 CFR 122.21). The RPA spreadsheet estimates the 95th percentile upper
concentration of each pollutant. The Predicted Max concentrations are compared to the Total
allowable concentrations to determine if a permit limit is necessary. If the predicted max exceeds
the acute or chronic Total allowable concentrations, the discharge is considered to show
reasonable potential to violate the water quality standard, and a permit limit (Total allowable
concentration) is included in the permit in accordance with the U.S. EPA Technical Support
Document for Water Quality -Based Toxics Control published in 1991.
7. When appropriate, permit writers develop facility specific compliance schedules in accordance
with the EPA Headquarters Memo dated May 10, 2007 from James Hanlon to Alexis Strauss on
40 CFR 122.47 Compliance Schedule Requirements.
The Total Chromium NC WQS was removed and replaced with trivalent chromium and
hexavalent chromium Water Quality Standards. As a cost savings measure, total chromium data
results may be used as a conservative surrogate in cases where there are no analytical results
based on chromium III or VI. In these cases, the projected maximum concentration (95th %) for
total chromium will be compared against water quality standards for chromium III and
chromium VI.
9. Effluent hardness sampling and instream hardness sampling, upstream of the discharge, are
inserted into all permits with facilities monitoring for hardness -dependent metals to ensure the
accuracy of the permit limits and to build a more robust hardness dataset.
10. Hardness and flow values used in the Reasonable Potential Analysis for this permit included:
Parameter
Value
Comments (Data Source)
Average Effluent Hardness (mg/L)
[Total as, CaCO3 or (Ca+Mg)]
52.02
Average from 812019 to 412023
samples
Average Upstream Hardness (mg/L)
[Total as, CaCO3 or (Ca+Mg)]
25
Default value used; Average
upstream hardness < 25 mg/L
7Q10 summer (cfs)
466.0
Historical; Previous Fact Sheet
1Q10 (cfs)
376.3
Calculated in RPA
Permitted Flow (MGD)
40.0
NPDES Files
Date: 7/24/2023
Permit Writer: Nick Coco
Page 4 of 4

NCO024911 French Broad River WRF
CBOD monthly removal rate
Month
January-19
February-19
March-19
April-19
May-19
June-19
July-19
August-19
September-19
October-19
November-19
December-19
January-20
February-20
March-20
April-20
May-20
June-20
July-20
August-20
September-20
October-20
November-20
December-20
January-21
February-21
March-21
April-21
May-21
June-21
RR (%)
89.53
90.17
92.72
90.19
93.02
93.74
93.46
94.55
95.16
95.13
94.54
93.03
91.89
89.10
92.00
92.46
91.23
93.26
93.36
92.98
93.15
93.89
92.32
92.44
92.90
88.97
92.79
91.61
92.29
92.82
Month
July-21
August-21
September-21
October-21
November-21
December-21
January-22
February-22
March-22
April-22
May-22
June-22
July-22
August-22
September-22
October-22
November-22
December-22
January-23
February-23
March-23
April-23
May-23
June-23
July-23
August-23
September-23
October-23
November-23
December-23
Overall BOD removal rate
RR (%)
92.64
92.43
93.37
92.82
92.80
91.94
94.11
93.32
91.75
94.16
90.55
93.09
93.68
92.22
93.06
92.81
94.56
88.26
91.31
93.34
94.72
93.34
92.60
6/26/2023
TSS monthly removal rate
Month
January-19
February-19
March-19
April-19
May-19
June-19
July-19
August-19
September-19
October-19
November-19
December-19
January-20
February-20
March-20
Apri I-20
May-20
June-20
July-20
August-20
September-20
October-20
November-20
December-20
January-21
February-21
March-21
April-21
May-21
June-21
RR (%)
89.69
91.79
95.83
94.88
95.54
96.04
95.55
96.35
96.52
96.95
94.90
93.28
91.33
87.90
93.29
92.58
92.02
94.07
94.29
94.74
94.09
94.32
93.88
94.08
93.00
90.72
90.80
92.18
92.20
94.31
Month
July-21
August-21
September-21
October-21
November-21
December-21
January-22
February-22
March-22
April-22
May-22
June-22
July-22
August-22
September-22
October-22
November-22
December-22
January-23
February-23
March-23
April-23
May-23
June-23
July-23
August-23
September-23
October-23
November-23
December-23
Overall TSS removal rate
RR (%)
94.63
92.94
95.04
94.31
94.98
94.49
94.62
92.22
91.99
95.78
94.93
94.60
95.64
95.72
96.40
95.29
95.41
91.67
91.95
93.46
95.19
95.69
93.92

6/26/23 WQS = 12 ng/L
Facility Name
French Broad River WRF/NC0024911
/Permit No. :
Total Mercury 1631E PQL = 0.5 ng/L
Date Modifier Data Entry
Value
8/6/19
10.9
10.9
8/7/19
0.891
0.891
11/5/19
12.5
12.5
11/7/19
9.51
9.51
2/18/20
9.85
9.85
5/14/20
10.2
10.2
6/3/20
8.32
8.32
8/5/20
9.05
9.05
11/5/20
8.99
8.99
5/11/21
18
18
5/27/21
26.1
26.1
8/23/22 <
0.2
0.5
2/9/23
28.2
28.2
MERCURY WQBEL/TBEL EVALUATION
No Limit Required
MMP Required
7Q10s = 466.000 cfs WQBEL =
Permitted Flow = 40.000
V:2013-6
102.19 ng/L
47 ng/L
8.5 ng/L - Annual Average for 2019
9.3 ng/L - Annual Average for 2020
22.1 ng/L - Annual Average for 2021
0.5 ng/L - Annual Average for 2022
28.2 ng/L - Annual Average for 2023

French Broad River WRF/NC0024911
Mercury Data Statistics (Method 1631E)
2019
2020
2021
2022
# of Samples
4
5
2
1
Annual Average, ng/L
8.5
9.3
22.1
0.50
Maximum Value, ng/L
12.50
10.20
26.10
0.5
TBEL, ng/L
47
WQBEL, ng/L
102.2
2023
28.2
28.2

Facility: French Broad River WRF
Permit No. NC0024911
Prepared By: N. Coco
Use Site Specific (FW, SW)
Receiving Water Class
Supplemental Class
WS Classification (if needed)
Location (no site spec temp.)
Use Site Specific pH
Is Class PNA/HQW
Effluent Temperature (Summer)
Effluent Temperature (Winter)
Effluent pH (Summer)
Effluent pH (Winter)
NH3/TRC WLA Calculations
Yes
FW
Yes
Receiving water pH(upstream-summer)
Receiving water pH (upstream -winter)
Temperature (upstream -summer)
Temperature (upstream -winter)
If SW or FW-SW,salinity (ppt-summer)
If SW or FW-SW,salinity (ppt-winter)
Use Site Specific upstream ammonia
Bkgd ammonia (upstream -summer)
Bkgd ammonia (upstream -winter)
23.3 pH (mixed -summer)
17.8 # pH (mixed -winter)
7.47 Temperature (mixed -summer)
7.47 Temperature (mixed -winter)
Enter Design Flow (MGD): 40
Enter s7Q10 (cfs): 466
Enter w7Q10 (cfs): 595
Total Residual Chlorine (TRC)
Daily Maximum Limit (ug/1)
Ammonia (Summer)
Monthly Average Limit (mg NH3-N/1)
7.60
7.35
23.2
11.9
Yes
0.050
0.190
7.58
7.36
23.21
12.59
s7Q10 (CFS)
466
s7Q10 (CFS)
466
DESIGN FLOW (MGD)
40
DESIGN FLOW (MGD)
40
DESIGN FLOW (CFS)
62
DESIGN FLOW (CFS)
62
STREAM STD (UG/L)
17.0
INSTREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.05
IWC (%)
11.74
IWC (%)
11.74
Allowable Conc. (ug/1)
145
Allowable Monthly Conc. (mg/I)
8.5
Allowable Weekly Con. (mg/1)
21.4 2.5 X
Fecal Coliform
Ammonia (Winter)
Monthly Average Limit:
200/100mi
Monthly Average Limit (mg NH3-N/1)
(If DF >331; Monitor)
(If DF<331; Limit)
w7Q10 (CFS)
595
Dilution Factor (DF)
8.52
DESIGN FLOW (MGD)
40
DESIGN FLOW (CFS)
62
INSTREAM STD (MG/L)
2.5
Upstream Bkgd (mg/1)
0.190
IWC (%)
9.44
Allowable Monthly Conc. (mg/I)
24.7
Allowable Weekly Conc. (mg/1)
61.8 2.5 X
If ammonia toxicity is limiting, winter ammonia (NH3-N) limits cannot exceed twice summer (15A NCAC 2B .0404(c)):
Total Residual Chlorine I
1. Cap Daily Max limit at 28 ug/l to protect for acute toxicity

Summer
Winter
Ammonia
pH
Temp
pH
Temp
Summer
Winter
Effluent 90th
7.47
23.3
7.47
17.8
Upstream 90th
7.60
23.2
7.35
11.9
0.05
0.19

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NCO024911 MRS Betweel 6 - 2018 and 6 - 2023 Region: %
Facility Name: % Param Nam(% County: %
Major Minor: %
Report Date: 06/22/22 Page 1 of 4
Violation Category:Limit Violation Program Category:
Subbasin: % Violation Action: %
PERMIT: NCO024911 FACILITY: Metropolitan Sewerage District of Buncombe County
North Carolina - French Broad River WRF
COUNTY: Buncombe
REGION: Asheville
Limit Violation
MONITORING
VIOLATION
UNIT OF
CALCULATED
%
REPORT
OUTFALL LOCATION
PARAMETER
DATE
FREQUENCY
MEASURE
LIMIT
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
02 - 2021
001 Effluent
BOD, Carbonaceous 05 Day,
02/13/21
5 X week
mg/I
40
41.46
3.6
Weekly Average
Proceed to NOV
20 C
Exceeded
08 - 2018
001 Effluent
Chlorine, Total Residual
08/16/18
5 X week
ug/I
28
43
53.6
Daily Maximum
No Action, BPJ
Exceeded
11 -2018
001 Effluent
Chlorine, Total Residual
11/15/18
5 X week
ug/I
28
110
292.9
Daily Maximum
Proceed to NOV
Exceeded
06-2018
001 Effluent
Coliform, Fecal MF, MFC
06/02/18
5 X week
#/100ml
400
2,420
505
Weekly Geometric Mean
No Action, BPJ
Broth, 44.5 C
Exceeded
10 -2018
MW3 / CONVO02935
Barium, Total (as Ba)
10/31/18
3 X year
mg/I
700
40,700
5,714.3
Limit Exceeded
No Action, Data
Entry Error
01 -2019
MW3 / CONVO02935
Barium, Total (as Ba)
01/31/19
3 X year
mg/I
700
38,300
5,371.4
Limit Exceeded
No Action, Data
Entry Error
06 - 2018
MW4 / CONVO03466
Barium, Total (as Ba)
06/30/18
3 X year
mg/I
700
6,438
819.7
Limit Exceeded
No Action, Data
Entry Error
10-2018
MW4 / CONVO03466
Barium, Total (as Ba)
10/31/18
3 X year
mg/I
700
57,600
8,128.6
Limit Exceeded
No Action, Data
Entry Error
06 -2018
MW4 / CONVO03466
Nitrogen, Ammonia Total (as
06/30/18
3 X year
ug/I
1,500
1,700
13.3
Limit Exceeded
No Action, BPJ
N)
01 -2019
MW4 / CONVO03466
Nitrogen, Ammonia Total (as
01/31/19
3 X year
ug/I
1,500
2,200
46.7
Limit Exceeded
No Action, BPJ
N)
01 -2020
MW-5 / BIMS052231
Iron, Total (as Fe)
01/31/20
3 X year
ug/I
300
524
74.7
Limit Exceeded
No Action, BPJ
06 -2022
MW-5 / BIMS052231
Iron, Total (as Fe)
06/30/22
3 X year
ug/I
300
382
27.3
Limit Exceeded
No Action, BPJ
06 -2019
MW-5 / BIMS052231
Manganese, Total (as Mn)
06/30/19
3 X year
ug/I
50
482
864
Limit Exceeded
No Action, BPJ
10 -2019
MW-5 / BIMS052231
Manganese, Total (as Mn)
10/31/19
3 X year
ug/I
50
302
504
Limit Exceeded
No Action, BPJ
01 -2020
MW-5 / BIMS052231
Manganese, Total (as Mn)
01/31/20
3 X year
ug/I
50
533
966
Limit Exceeded
No Action, BPJ
06-2022
MW-5 / BIMS052231
Manganese, Total (as Mn)
06/30/22
3 X year
ug/I
50
76.2
52.4
Limit Exceeded
No Action, BPJ
10-2022
MW-6R / BIMS052233
Chromium, Total (as Cr)
10/31/22
3 X year
ug/I
10
17.4
74.0
Limit Exceeded
None

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NCO024911 MRS Betweel 6 - 2018 and 6 - 2023 Region: %
Facility Name: % Param Nam(% County: %
Major Minor: %
Report Date: 06/22/2� Page 2 of 4
Violation Category:Limit Violation Program Category: %
Subbasin: % Violation Action: %
PERMIT: NCO024911
FACILITY: Metropolitan Sewerage District of Buncombe County
North Carolina - French Broad River WRF
COUNTY: Buncombe
REGION: Asheville
Limit Violation
MONITORING
VIOLATION
UNIT OF
CALCULATED
%
REPORT
WELL LOCATION
PARAMETER
DATE
FREQUENCY
MEASURE
LIMIT
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
06-2019
MW-6R / BIMS052233
Iron, Total (as Fe)
06/30/19
3 X year
ug/I
300
7,480
2,393.3
Limit Exceeded
No Action, BPJ
10-2019
MW-6R / BIMS052233
Iron, Total (as Fe)
10/31/19
3 X year
ug/I
300
50,800
16,833.3
Limit Exceeded
No Action, BPJ
01 -2020
MW-6R / BIMS052233
Iron, Total (as Fe)
01/31/20
3 X year
ug/I
300
43,000
14,233.3
Limit Exceeded
No Action, BPJ
06 -2020
MW-6R / BIMS052233
Iron, Total (as Fe)
06/30/20
3 X year
ug/I
300
1,820
506.7
Limit Exceeded
No Action, BPJ
10-2020
MW-6R / BIMS052233
Iron, Total (as Fe)
10/31/20
3 X year
ug/I
300
5,410
1,703.3
Limit Exceeded
No Action, BPJ
01 -2021
MW-6R / BIMS052233
Iron, Total (as Fe)
01/31/21
3 X year
ug/I
300
1,250
316.7
Limit Exceeded
No Action, BPJ
06 -2021
MW-6R / BIMS052233
Iron, Total (as Fe)
06/30/21
3 X year
ug/I
300
5,360
1,686.7
Limit Exceeded
No Action, BPJ
10-2021
MW-6R / BIMS052233
Iron, Total (as Fe)
10/31/21
3 X year
ug/I
300
1,080
260
Limit Exceeded
No Action, BPJ
01 -2022
MW-6R / BIMS052233
Iron, Total (as Fe)
01/31/22
3 X year
ug/I
300
9,200
2,966.7
Limit Exceeded
No Action, BPJ
06-2022
MW-6R / BIMS052233
Iron, Total (as Fe)
06/30/22
3 X year
ug/I
300
16,900
5,533.3
Limit Exceeded
No Action, BPJ
10-2022
MW-6R / BIMS052233
Iron, Total (as Fe)
10/31/22
3 X year
ug/I
300
34,800
11,500
Limit Exceeded
None
06 -2019
MW-6R / BIMS052233
Manganese, Total (as Mn)
06/30/19
3 X year
ug/I
50
14,100
28,100
Limit Exceeded
No Action, BPJ
10-2019
MW-6R / BIMS052233
Manganese, Total (as Mn)
10/31/19
3 X year
ug/I
50
12,700
25,300
Limit Exceeded
No Action, BPJ
01 -2020
MW-6R / BIMS052233
Manganese, Total (as Mn)
01/31/20
3 X year
ug/I
50
10,000
19,900
Limit Exceeded
No Action, BPJ
06-2020
MW-6R / BIMS052233
Manganese, Total (as Mn)
06/30/20
3 X year
ug/I
50
7,880
15,660
Limit Exceeded
No Action, BPJ
10 -2020
MW-6R / BIMS052233
Manganese, Total (as Mn)
10/31/20
3 X year
ug/I
50
9,330
18,560
Limit Exceeded
No Action, BPJ
01 -2021
MW-6R / BIMS052233
Manganese, Total (as Mn)
01/31/21
3 X year
ug/I
50
8,510
16,920
Limit Exceeded
No Action, BPJ
10 -2021
MW-6R / BIMS052233
Manganese, Total (as Mn)
10/31/21
3 X year
ug/I
50
6,690
13,280
Limit Exceeded
No Action, BPJ
01 -2022
MW-6R / BIMS052233
Manganese, Total (as Mn)
01/31/22
3 X year
ug/I
50
12,300
24,500
Limit Exceeded
No Action, BPJ

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NCO024911 MRS Betweel 6 - 2018 and 6 - 2023 Region: %
Facility Name: % Param Nam(% County: %
Major Minor: %
Report Date: 06/22/2� Page 3 of 4
Violation Category:Limit Violation Program Category: %
Subbasin: % Violation Action: %
PERMIT: NCO024911
FACILITY: Metropolitan Sewerage District of Buncombe County
North Carolina - French Broad River WRF
COUNTY: Buncombe
REGION: Asheville
Limit Violation
MONITORING
VIOLATION
UNIT OF
CALCULATED
%
REPORT
WELL LOCATION
PARAMETER
DATE
FREQUENCY
MEASURE
LIMIT
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
06-2022
MW-6R / BIMS052233
Manganese, Total (as Mn)
06/30/22
3 X year
ug/I
50
14,100
28,100
Limit Exceeded
No Action, BPJ
10-2022
MW-6R / BIMS052233
Manganese, Total (as Mn)
10/31/22
3 X year
ug/I
50
11,200
22,300
Limit Exceeded
None
06-2019
MW-7 / BIMS052232
Iron, Total (as Fe)
06/30/19
3 X year
ug/I
300
1,730
476.7
Limit Exceeded
No Action, BPJ
01 -2020
MW-7 / BIMS052232
Iron, Total (as Fe)
01/31/20
3 X year
ug/I
300
627
109
Limit Exceeded
No Action, BPJ
06 -2020
MW-7 / BIMS052232
Iron, Total (as Fe)
06/30/20
3 X year
ug/I
300
447
49
Limit Exceeded
No Action, BPJ
10 -2020
MW-7 / BIMS052232
Iron, Total (as Fe)
10/31/20
3 X year
ug/I
300
831
177
Limit Exceeded
No Action, BPJ
01 -2021
MW-7 / BIMS052232
Iron, Total (as Fe)
01/31/21
3 X year
ug/I
300
334
11.3
Limit Exceeded
No Action, BPJ
06-2019
MW-7 / BIMS052232
Manganese, Total (as Mn)
06/30/19
3 X year
ug/I
50
14,400
28,700
Limit Exceeded
No Action, BPJ
01 -2020
MW-7 / BIMS052232
Manganese, Total (as Mn)
01/31/20
3 X year
ug/I
50
125
150
Limit Exceeded
No Action, BPJ
06-2020
MW-7 / BIMS052232
Manganese, Total (as Mn)
06/30/20
3 X year
ug/I
50
308
516
Limit Exceeded
No Action, BPJ
06-2021
MW-7 / BIMS052232
Manganese, Total (as Mn)
06/30/21
3 X year
ug/I
50
176
252
Limit Exceeded
No Action, BPJ
10-2021
MW-7 / BIMS052232
Manganese, Total (as Mn)
10/31/21
3 X year
ug/I
50
740
1,380
Limit Exceeded
No Action, BPJ
06-2022
MW-7 / BIMS052232
Manganese, Total (as Mn)
06/30/22
3 X year
ug/I
50
191
282
Limit Exceeded
No Action, BPJ
10-2022
MW-7 / BIMS052232
Manganese, Total (as Mn)
10/31/22
3 X year
ug/I
50
444
788
Limit Exceeded
None
06 -2019
MW-8R / BIMS052230
Iron, Total (as Fe)
06/30/19
3 X year
ug/I
300
8,660
2,786.7
Limit Exceeded
No Action, BPJ
10 -2019
MW-8R / BIMS052230
Iron, Total (as Fe)
10/31/19
3 X year
ug/I
300
2,860
853.3
Limit Exceeded
No Action, BPJ
01 -2020
MW-8R / BIMS052230
Iron, Total (as Fe)
01/31/20
3 X year
ug/I
300
18,800
6,166.7
Limit Exceeded
No Action, BPJ
06 -2020
MW-8R / BIMS052230
Iron, Total (as Fe)
06/30/20
3 X year
ug/I
300
70,700
23,466.7
Limit Exceeded
No Action, BPJ
10-2020
MW-8R / BIMS052230
Iron, Total (as Fe)
10/31/20
3 X year
ug/I
300
61,600
20,433.3
Limit Exceeded
No Action, BPJ

MONITORING REPORT(MR) VIOLATIONS for:
Permit: NCO024911 MRS Betweel 6 - 2018 and 6 - 2023 Region: %
Facility Name: % Param Nam(% County: %
Major Minor: %
Report Date: 06/22/2� Page 4 of 4
Violation Category:Limit Violation Program Category: %
Subbasin: % Violation Action: %
PERMIT: NCO024911
FACILITY: Metropolitan Sewerage District of Buncombe County
North Carolina - French Broad River WRF
COUNTY: Buncombe
REGION: Asheville
Limit Violation
MONITORING
VIOLATION
UNIT OF
CALCULATED
%
REPORT
WELL LOCATION
PARAMETER
DATE
FREQUENCY
MEASURE
LIMIT
VALUE
Over
VIOLATION TYPE
VIOLATION ACTION
01 -2021
MW-8R / BIMS052230
Iron, Total (as Fe)
01/31/21
3 X year
ug/I
300
69,000
22,900
Limit Exceeded
No Action, BPJ
06 -2021
MW-8R / BIMS052230
Iron, Total (as Fe)
06/30/21
3 X year
ug/I
300
50,700
16,800
Limit Exceeded
No Action, BPJ
10 -2021
MW-8R / BIMS052230
Iron, Total (as Fe)
10/31/21
3 X year
ug/I
300
37,600
12,433.3
Limit Exceeded
No Action, BPJ
01 -2022
MW-8R / BIMS052230
Iron, Total (as Fe)
01/31/22
3 X year
ug/I
300
32,300
10,666.7
Limit Exceeded
No Action, BPJ
06-2022
MW-8R / BIMS052230
Iron, Total (as Fe)
06/30/22
3 X year
ug/I
300
49,900
16,533.3
Limit Exceeded
No Action, BPJ
10-2022
MW-8R / BIMS052230
Iron, Total (as Fe)
10/31/22
3 X year
ug/I
300
18,400
6,033.3
Limit Exceeded
None
06 -2019
MW-8R / BIMS052230
Manganese, Total (as Mn)
06/30/19
3 X year
ug/I
50
6,820
13,540
Limit Exceeded
No Action, BPJ
10-2019
MW-8R / BIMS052230
Manganese, Total (as Mn)
10/31/19
3 X year
ug/I
50
10,400
20,700
Limit Exceeded
No Action, BPJ
01 -2020
MW-8R / BIMS052230
Manganese, Total (as Mn)
01/31/20
3 X year
ug/I
50
11,700
23,300
Limit Exceeded
No Action, BPJ
06-2020
MW-8R / BIMS052230
Manganese, Total (as Mn)
06/30/20
3 X year
ug/I
50
19,700
39,300
Limit Exceeded
No Action, BPJ
10-2020
MW-8R / BIMS052230
Manganese, Total (as Mn)
10/31/20
3 X year
ug/I
50
14,800
29,500
Limit Exceeded
No Action, BPJ
01 -2021
MW-8R / BIMS052230
Manganese, Total (as Mn)
01/31/21
3 X year
ug/I
50
20,100
40,100
Limit Exceeded
No Action, BPJ
06-2021
MW-8R / BIMS052230
Manganese, Total (as Mn)
06/30/21
3 X year
ug/I
50
15,000
29,900
Limit Exceeded
No Action, BPJ
10-2021
MW-8R / BIMS052230
Manganese, Total (as Mn)
10/31/21
3 X year
ug/I
50
11,000
21,900
Limit Exceeded
No Action, BPJ
01 -2022
MW-8R / BIMS052230
Manganese, Total (as Mn)
01/31/22
3 X year
ug/I
50
9,780
19,460
Limit Exceeded
No Action, BPJ
06 -2022
MW-8R / BIMS052230
Manganese, Total (as Mn)
06/30/22
3 X year
ug/I
50
17,000
33,900
Limit Exceeded
No Action, BPJ
10-2022
MW-8R / BIMS052230
Manganese, Total (as Mn)
10/31/22
3 X year
ug/I
50
8,850
17,600
Limit Exceeded
None

United States Environmental Protection Agency
Form Approved.
EPA Washington, D.C. 20460
OMB No. 2040-0057
Water Compliance Inspection Report
Approval expires 8-31-98
Section A: National Data System Coding (i.e., PCS)
Transaction Code NPDES yr/mo/day Inspection Type Inspector Fac Type
1 IN 1 2 u 3 I NC0024911 I11 121 23/02/23 I17 18I D I 19 I s I 20L]
21111I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I II I I I I I r6
Inspection
Work Days Facility Self -Monitoring Evaluation Rating B1 QA ---------------------- Reserved -------------------
67
I 72 I n, I 71 I 74 79 I I I I I I I80
701 I 71 I LL -1 I I
LJ
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
Entry Time/Date
Permit Effective Date
POTW name and NPDES permit Number)
08:30AM 23/02/23
18/10/01
French Broad River WRF
NC Hwy 251
Exit Time/Date
Permit Expiration Date
Asheville NC 28814
01:OOPM 23/02/23
22/12/31
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
Other Facility Data
Bart T Farmer/ORC/828-225-8224/
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Thomas E Hartye,2028 Riverside Dr Asheville NC 288043054/General
Manager/828-225-8399/ No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Pretreatment
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s) and Signature(s) of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Timothy H Heim DWR/ARO WQ/828-296-4665/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page#

NPDES yr/mo/day Inspection Type
NCO024911 I11 12I 23/02/23 117 18 1 p I
(Cont.)
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Tim Heim of the Asheville Regional Office performed a Pretreatment Compliance Inspection (PCI) on
February 21st & 23rd, 2023. Chad Ledford (MSD Pretreatment), and Leslie Frady (Milkco EH&S)
assisted with the inspection and with records and sampling results review.
The pretreatment program, associated record keeping, and the relationship with the IUs were in good
order at the time of the inspection and compliant with permit conditions.
DEQ ARO staff observed pretreatment inspection and sampling of an Industrial User: (IU) in the
program, Milkco Inc. (IUP # S-036).
See attached NC DEQ Pretreatment Compliance Inspection form for details.
Page#

Permit: NC0024911
Inspection Date: 02/23/2023
Owner -Facility: French Broad River WRF
Inspection Type: Pretreatment Compliance
Yes No NA NE
Page#

United States Environmental Protection Agency
Form Approved.
EPA Washington, D.C. 20460
OMB No. 2040-0057
Water Compliance Inspection Report
Approval expires 8-31-98
Section A: National Data System Coding (i.e., PCS)
Transaction Code NPDES yr/mo/day Inspection Type Inspector Fac Type
1 IN 1 2 u 3 I NC0024911 111 121 22/04/14 I17 18 LC] I 19 I s I 20L]
21111I I I I I I I II I I I I I I I I I I I I I I I I I I I I I I I II I I I I I r6
Inspection
Work Days Facility Self -Monitoring Evaluation Rating B1 QA ---------------------- Reserved -------------------
67
I 72 I n, I 71 I 74 79 I I I I I I I80
701 I 71 I LL -1 I I
LJ
Section B: Facility Data
Name and Location of Facility Inspected (For Industrial Users discharging to POTW, also include
Entry Time/Date
Permit Effective Date
POTW name and NPDES permit Number)
02:OOPM 22/04/14
18/10/01
French Broad River WRF
NC Hwy 251
Exit Time/Date
Permit Expiration Date
Asheville NC 28814
04:30PM 22/04/14
22/12/31
Name(s) of Onsite Representative(s)/Titles(s)/Phone and Fax Number(s)
Other Facility Data
Roger C Edwards/ORC/828-225-8224/
Name, Address of Responsible Official/Title/Phone and Fax Number
Contacted
Thomas E Hartye,2028 Riverside Dr Asheville NC 288043054/General
Manager/828-225-8399/ No
Section C: Areas Evaluated During Inspection (Check only those areas evaluated)
Permit 0 Operations & Maintenar 0 Records/Reports Self -Monitoring Progran
Facility Site Review
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
(See attachment summary)
Name(s) and Signature(s) of Inspector(s) Agency/Office/Phone and Fax Numbers Date
Timothy H Heim DWR/ARO WQ/828-296-4665/
Signature of Management Q A Reviewer Agency/Office/Phone and Fax Numbers Date
EPA Form 3560-3 (Rev 9-94) Previous editions are obsolete.
Page#

NPDES yr/mo/day Inspection Type
NCO024911 I11 12I 22/04/14 117 18 i c i
(Cont.)
Section D: Summary of Finding/Comments (Attach additional sheets of narrative and checklists as necessary)
Tim Heim of the Asheville Regional Office performed a Compliance Inspection of the Facility on April
14, 2022. Roger Edwards (ORC) was present and assisted with the inspection. The facility appeared
well operated at the time of the inspection, and in compliance with Permit NC0024911.
The following additional items were noted at the time of the inspection:
The new high rate primary clarifier is operational and undergoing startup commissioning
The facility is evaluating future upgrades to biological treatment and other components. Consider
discussions with ARO regarding maintaining compliance during construction of these upgrades.
Page#

Permit: NCO024911
Inspection Date: 04/14/2022
Owner -Facility: French Broad River WRF
Inspection Type: Compliance Evaluation
Operations & Maintenance Yes No NA NE
Is the plant generally clean with acceptable housekeeping? 0 ❑ ❑ ❑
Does the facility analyze process control parameters, for ex: MLSS, MCRT, Settleable ❑ ❑ ❑
Solids, pH, DO, Sludge Judge, and other that are applicable?
Comment:
Permit
Yes
No
NA
NE
(If the present permit expires in 6 months or less). Has the permittee submitted a new
❑
❑
0
❑
application?
Is the facility as described in the permit?
0
❑
❑
❑
# Are there any special conditions for the permit?
❑
■
❑
❑
Is access to the plant site restricted to the general public?
0
❑
❑
❑
Is the inspector granted access to all areas for inspection?
0
❑
❑
❑
Comment:
Pump Station - Influent
Yes
No
NA
NE
Is the pump wet well free of bypass lines or structures?
0
❑
❑
❑
Is the wet well free of excessive grease?
0
❑
❑
❑
Are all pumps present?
■
❑
❑
❑
Are all pumps operable?
0
❑
❑
❑
Are float controls operable?
0
❑
❑
❑
Is SCADA telemetry available and operational?
0
❑
❑
❑
Is audible and visual alarm available and operational?
M
❑
❑
❑
Comment:
Bar Screens
Yes
No
NA NE
Type of bar screen
a.Manual
❑
b.Mechanical
Are the bars adequately screening debris?
0
❑
❑
❑
Is the screen free of excessive debris?
■
❑
❑
❑
Is disposal of screening in compliance?
0
❑
❑
❑
Is the unit in good condition?
0
❑
❑
❑
Comment:
Page# 3

Permit: NC0024911 Owner -Facility: French Broad River WRF
Inspection Date: 04/14/2022 Inspection Type: Compliance Evaluation
Grit Removal Yes No NA NE
Type of grit removal
a.Manual ❑
b.Mechanical
Is the grit free of excessive organic matter? ■ ❑ ❑ ❑
Is the grit free of excessive odor? 0 ❑ ❑ ❑
# Is disposal of grit in compliance? 0 ❑ ❑ ❑
Comment:
Primary Clarifier
Yes
No
NA
NE
Is the clarifier free of black and odorous wastewater?
0
❑
❑
❑
Is the site free of excessive buildup of solids in center well of circular clarifier?
❑
❑
0
❑
Are weirs level?
0
❑
❑
❑
Is the site free of weir blockage?
0
❑
❑
❑
Is the site free of evidence of short-circuiting?
0
❑
❑
❑
Is scum removal adequate?
0
❑
❑
❑
Is the site free of excessive floating sludge?
■
❑
❑
❑
Is the drive unit operational?
❑
❑
0
❑
Is the sludge blanket level acceptable?
❑
❑
0
❑
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
❑
❑
0
❑
Comment: Rapid ActiFlow settling type primary clarifier.
Rotating Biological Contactor
Yes
No
NA
NE
Is the unit free of excessive sloughing of growth?
0
❑
❑
❑
Is the unit operational?
0
❑
❑
❑
Are media panels in good condition?
0
❑
❑
❑
Comment:
Secondary Clarifier
Yes
No
NA
NE
Is the clarifier free of black and odorous wastewater?
0
❑
❑
❑
Is the site free of excessive buildup of solids in center well of circular clarifier?
❑
❑
0
❑
Are weirs level?
0
❑
❑
❑
Is the site free of weir blockage?
■
❑
❑
❑
Is the site free of evidence of short-circuiting?
M
❑
❑
❑
Page# 4

Permit: NC0024911
Inspection Date: 04/14/2022
Secondary Clarifier
Is scum removal adequate?
Is the site free of excessive floating sludge?
Is the drive unit operational?
Owner -Facility: French Broad River WRF
Inspection Type: Compliance Evaluation
Is the return rate acceptable (low turbulence)?
Is the overflow clear of excessive solids/pin floc?
Is the sludge blanket level acceptable? (Approximately'/4 of the sidewall depth)
Comment: Rectangular clarifiers.
Filtration (High Rate Tertiary)
Type of operation:
Is the filter media present?
Is the filter surface free of clogging?
Is the filter free of growth?
Is the air scour operational?
Is the scouring acceptable?
Is the clear well free of excessive solids and filter media?
Comment: Textile base disk filters.
Disinfection -Liquid
Is there adequate reserve supply of disinfectant?
(Sodium Hypochlorite) Is pump feed system operational?
Is bulk storage tank containment area adequate? (free of leaks/open drains)
Is the level of chlorine residual acceptable?
Is the contact chamber free of growth, or sludge buildup?
Is there chlorine residual prior to de -chlorination?
Comment:
De -chlorination
Type of system ?
Is the feed ratio proportional to chlorine amount (1 to 1)?
Is storage appropriate for cylinders?
# Is de -chlorination substance stored away from chlorine containers?
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Yes No NA NE
Cross flow
■ ❑ ❑ ❑
■ ❑ ❑ ❑
■ ❑ ❑ ❑
❑ ❑ ■ ❑
❑ ❑ ■ ❑
■ ❑ ❑ ❑
Yes No NA NE
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
❑ ❑ ❑ ■
■ ❑ ❑ ❑
❑ ❑ ❑ ■
Yes No NA NE
Liquid
• ❑ ❑ ❑
• ❑ ❑ ❑
• ❑ ❑ ❑
Page# 5

Permit: NC0024911
Inspection Date: 04/14/2022
De -chlorination
Comment:
Are the tablets the proper size and type?
Are tablet de -chlorinators operational?
Number of tubes in use?
Comment:
Owner -Facility: French Broad River WRF
Inspection Type: Compliance Evaluation
Standby Power
Is automatically activated standby power available?
Is the generator tested by interrupting primary power source?
Is the generator tested under load?
Was generator tested & operational during the inspection?
Do the generator(s) have adequate capacity to operate the entire wastewater site?
Is there an emergency agreement with a fuel vendor for extended run on back-up
power?
Is the generator fuel level monitored?
Comment:
Yes No NA NE
❑ ❑ ■ ❑
❑ ❑ ■ ❑
Yes
No
NA
NE
■
❑
❑
❑
■
❑
❑
❑
■
❑
❑
❑
❑
❑
❑
■
❑
❑
❑
❑
❑
❑
❑
❑
❑
Page# 6

Whole Effluent Toxicity Testing and Self Monitoring Summary
Buncombe County MSD
NCO024911/001
County:
Buncombe
Region:
ARO
Basin: FRB02
Feb May Aug Nov
Ceri7dPF
Begin:
10/1/2018 chr lim: 12%
NonComp: Single
7Q10:
466.0
PF: 40.0 IWC:
12.0
Freq: Q
J
F M
A M
J
J
A
S
O
2019
-
Pass -
- >48(P)
-
-
Pass
-
-
2020
-
Pass -
- Pass
-
-
>48(P)
-
-
2021
-
Pass -
- Pass
-
-
Pass
-
-
2022
-
Pass -
- Pass 33.9 (P)
-
-
Pass
-
-
2023
-
Pass Pass -
- -
-
-
-
-
-
Bunn WWTP
NCO042269/001
County:
Franklin
Region:
RRO
Basin: TAR01
Mar Jun Sep Dec
Ceri7dPF
Begin:
8/1/2020
chr lim: 11%@ 0.15
NonComp: Single
7Q10:
1.8
PF: 0.15 IWC:
11
Freq: Q
J
F M
A M
J
J
A
S
O
2019
-
- Pass
- -
Pass
-
-
Pass
-
2020
-
- Pass
- -
Pass
-
-
Pass
-
2021
-
- Pass
- -
Pass
-
-
Pass
-
2022
-
- Pass
- -
Pass
-
-
Pass
-
2023
-
- Pass
- -
-
-
-
-
-
Burlington East WWTP
NCO023868/001
County:
Alamance
Region:
WSRO
Basin: CPF02
Feb May Aug Nov
Ceri7dPF
Begin:
7/1/2014
chr lim: 36%
NonComp: SINGLE
7Q10:
33.6
PF: 12.0 IWC:
36
Freq: Q
J
F M
A M
I
J
A
S
O
2019
-
Pass -
- Pass
-
-
Pass
-
-
2020
-
Pass -
- Pass
-
-
Pass
-
-
2021
-
Pass -
- Pass
-
-
Pass
-
-
2022
-
Pass -
- Pass
-
-
Pass
-
-
2023
-
Pass -
- -
-
-
-
-
-
Burlington Industries WWTP
NCO043320/001
County:
Richmond
Region:
FRO
Basin: YAD16
Feb May Aug Nov
Ceri7dPF
Begin:
6/1/2015
chr lim: 7%
NonComp: Single
7Q10:
25.0
PF: 1.2 IWC:
7.0
Freq: Q
J
F M
A M
J
J
A
S
O
2019
-
Pass -
- Pass
-
-
Pass
-
-
2020
-
Pass -
- Pass
-
-
Pass
-
-
2021
-
Pass -
- Pass
-
-
Pass
-
-
2022
-
Pass -
- Pass
-
-
Pass
-
-
2023
-
Pass -
- -
-
-
-
-
-
Burlington -South WWTP
NCO023876/001
County:
Alamance
Region:
WSRO
Basin: CPF02
Jan Apr Jul Oct
Ceri7dPF
Begin:
7/1/2014
chr lim: 86%
NonComp: Single
7Q10:
3.0
PF: 12.0 IWC:
86
Freq: Q
J
F M
A M
J
I
A
S
O
2019
Pass
- -
Pass -
-
Pass
-
-
Pass
2020
Pass
- -
Pass -
-
Pass
-
-
Pass
2021
Pass
- -
Pass -
-
Pass
-
-
Pass
2022
Pass
- -
Pass -
-
Pass
-
-
Pass
2023
Pass
- -
Pass -
-
-
-
-
-
SOC JOC:
N
Pass
Pass
Pass >48 (P)
Pass
SOC JOC:
N
SOC JOC:
N
Pass
Pass
Pass
Pass
SOC JOC:
N
Pass
Pass
Pass
Pass
SOC JOC:
N
C
D
Pass
Pass
Pass
Pass
G
C
0
Leeend: P= Fathead minnow (Pimohales oromelas). H=No Flow (facility is active). s = Solit test between Certified Labs
Page 13 of 115