NC0021873_Fact Sheet_20180627

Fact Sheet
NPDES Permit No. NCO021873
Permit Writer/Email Contact Qais Banihani, [e-mail]:
Date: April 23, 2018
Division/Branch: NC Division of Water Resources/NPDES Complex Permitting
Fact Sheet Template: Version 09Jan2017
Permitting Action:
N 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 2' 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:
Town of Mayodan/Mayodan WWTP
Applicant Address:
210 W Main Street, Mayodan, NC 27027
Facility Address:
293 Cardwell Road, Mayodan, NC 27027
Permitted Flow:
2.5, 3.0 & 4.5 MGD
Facility Type/Waste:
Major Municipal; domestic and Industrial
Facility Class:
Class III (2.5 MGD) and IV (3.0 & 4.5 MGD)
Treatment Units:
Mechanical Bar Screen, Aeration Basins, Secondary Clarifiers,
Chlorination, Dechlorination, Effluent flow meter, Sludge Digesters and
Sludge Thickeners
Pretreatment Program (Y/N)
Y
County:
Rockingham
Region
Winston-Salem
Page 1 of 13

Briefly describe the proposed permitting action and facility background:
The Town of Mayodan Wastewater Treatment Plant (WWTP), herein called Mayodan or Permittee, applied
for an NPDES permit renewal. The Permittee's 5 -year NPDES permit expired on May 31, 2017. Mayodan
services 2,468 local residents and receives industrial and domestic influent flow from the Towns of
Stoneville (1,042 residents) and Madison (2,205). In 2002, Mayodan applied for an expansion from 3.0
MGD to 4.5 MGD in order to add service to Stoneville and Madison. In 2007, because of loss of a major
SN, Mayodan applied for a flow reduction modification to the permit to downgrade to 2.5 MGD, thereby
going from a Class IV to a Class III facility with corresponding relaxed limits and monitoring conditions.
The average discharge for the period of January 2014 through February 2018 was 1.05 MGD. This facility
has 3 Significant Industrial Users (SIUs); Two Textile facilities and one Metal Finisher.
2. Receiving Waterbody Information:
Receiving Waterbody Information
Outfalls/Receiving Stream(s):
Outfall 001 — Mayo River
Stream Segment:
22-30-(10)
Stream Classification:
C
Drainage Area (mi2):
312
Summer 7Q10 (cfs)
75
Winter 7Q 10 (cfs):
131
30Q2 (cfs):
150
Average Flow (cfs):
362
IWC (% effluent):
5% (2.5 MGD), 6% (3.0 MGD) and 9% (4.5 MGD)
303(d) listed/parameter:
No
Subject to TMDL/parameter:
Yes- State wide TMDL for Mercury implementation
Subbasin/HUC:
Dan River Headwaters 03-02-02; 03010103
USGS Topo Quad:
B 19 NW
Page 2 of 13

3. Effluent Data Summary
Effluent data for Outfall 001 is summarized below for the period of January 2014 through February 2018.
Table 1. Effluent Data Summary Outfall 001
Page 3 of 13
Permit
Parameter
Units
Average
Max
Min
Limit
MA 2.5, 3 &4.5
Flow
MGD
1.05
5.34
0.07
WA 45.0
BOD summer
mg/l
6.34
49.0
< 2.0
MA 30.0
WA 45.0
BOD winter
mg/l
6.04
32.0
< 2.0
MA 30.0
BOD Removal
%
93.11
98.07
74.01
> 85.0
WA 45.0
TSS
mg/l
7.82
83.0
< 2.0
MA 30.0
TSS Removal
%
90.34
97.86
65.25
> 85.0
NH3N summer at 2.5
WA 35.0
mg/1
1.86
17.0
< 0.04
MGD
MA 16.0
NH3N summer at 3.0
WA 35.0
mg/1
1.86
17.0
< 0.04
MGD
MA 14.0
NH3N summer at 4.5
WA 27.0
mg/1
1.86
17.0
< 0.04
MGD
MA 9.0
NH3N winter at 2.5 MGD
mg/l
1.13
10.48
< 0.04
NH3N winter at 3.0 MGD
mg/l
1.13
10.48
< 0.04
WA 35.0
NH3N winter at 4.5 MGD
mg/l
1.13
10.48
< 0.04
MA 31.5
TRC
µg/1
23.92
50.0
1
DM 28.0
(geometric)
Fecal coliform
#/100 ml
180.86
4280
< 1
WA 400
MA 200
6.0 > pH <9.0
pH
SU
6.79
11.0
6.0
DO
mg/l
7.92
16.5
1.4
Temperature
°C
16.42
30
1.5
Conductivity
umhos/cm
392.02
731.2
7.0
Page 3 of 13

TN
mg/l
19.37
400.0
1.44
Average 7.0
TP
mg/l
2.12
7.71
0.13
17.8
Total Chromium at 2.5
Min 5.3
1
5.2
23.4
P g/l
5.0
5.0
5.0
MGD
Total Chromium at 3.0
DM 14,500
µg/1
5.0
5.0
5.0
MGD
MA 856
Total Chromium at 4.5
DM 10,000
µg/1
5.0
5.0
5.0
MGD
MA 587
Total Mercury
ng/L
4.47
11.9
< 1.0
AA 47
Total Silver
gg/l
1.47
< 10.0
< 1.0
Total Copper
gg/l
7.42
11.0
3.0
MA -Monthly Average, WA -Weekly Average, DM -Daily Maximum, DA=Daily
Average, AA -Annual 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/l 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 beproposedfor this permit
action: The current permit requires instream monitoring for Dissolved Oxygen (DO), Temperature,
Conductivity and pH. A review of instream data from June 2016 through February 2018 indicates that the
DO standard of 5 mg/L was maintained, and there were no significant differences between upstream and
downstream (ANOVA, p > 0.5). The average DO for upstream and downstream were 9.5 and 9.6,
respectively.
Temperature readings were nearly identical between upstream and downstream sites except with only one
set of measurements showing a differential greater than 2.8 degrees °C (12 °C for upstream and 15 °C for
downstream) in November 2016. Effluent temperature on that day was 11 °C. On the other hand,
conductivity readings between upstream and downstream locations were statistically significant (ANOVA,
p < 0.05). There was no significant differences between upstream and downstream pH readings (ANOVA,
p > 0.5). Instream data is summarized in tables 2 and 3.
Table 2: Upstream Instream Data (June 2016 - February 2018)
H
SU
Temperature
°C
DO
m /L
Conductivity
mhos/cm
Average 7.0
18.7
9.5
61.6
Max 8.2
31
17.8
89.2
Min 5.3
1
5.2
23.4
Page 4 of 13

Table 3: Downstream Instream Data (June 2016 - February 2018)
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): NO
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years):
The facility reported a total of 5 limit violations from August 2013 to March 2018. All the violations were
Fecal Coliform violations. TRC limit violations were not included since No action was required for values
reported < 50 ug/L. The Fecal Coliform exceeded the weekly geometric mean twice in 2013, once in each
2014, 2015 and 2017. Fecal Coliform limit violations resulted in 2 Notices of Violation (NOVs), 2 No
Actions and 1 Notice of Deficiency (NOD).
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): For the past four years, the facility passed 16 of 16 quarterly chronic toxicity tests as well
as all four 2" d species chronic toxicity tests.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in 2016 reported that the facility was operating properly.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206, the following stream flows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 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/l for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
Ifpermit limits are more stringent than TBELs, describe how limits were developed: NA
Page 5 of 13
H
Temperature
DO Conductivity
SU
°C
m /L mhos/cm
Average
7.0
18.8
9.6 67.2
Max
8.2
31
18.7 103.8
Min
5.2
1
5.5 45.6
Is this facility a member of a Monitoring Coalition with waived instream monitoring (YIN): NO
Name of Monitoring Coalition: NA
5. Compliance Summary
Summarize the compliance record with permit effluent limits (past 5 years):
The facility reported a total of 5 limit violations from August 2013 to March 2018. All the violations were
Fecal Coliform violations. TRC limit violations were not included since No action was required for values
reported < 50 ug/L. The Fecal Coliform exceeded the weekly geometric mean twice in 2013, once in each
2014, 2015 and 2017. Fecal Coliform limit violations resulted in 2 Notices of Violation (NOVs), 2 No
Actions and 1 Notice of Deficiency (NOD).
Summarize the compliance record with aquatic toxicity test limits and any second species test results
(past 5 years): For the past four years, the facility passed 16 of 16 quarterly chronic toxicity tests as well
as all four 2" d species chronic toxicity tests.
Summarize the results from the most recent compliance inspection: The last facility inspection conducted
in 2016 reported that the facility was operating properly.
6. Water Quality -Based Effluent Limitations (WQBELs)
Dilution and Mixing Zones
In accordance with 15A NCAC 2B.0206, the following stream flows are used for dilution considerations
for development of WQBELs: 1 Q 10 streamflow (acute Aquatic Life); 7Q 10 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/l for Municipals) may be appropriate if deemed more stringent based on dilution and
model results.
Ifpermit limits are more stringent than TBELs, describe how limits were developed: NA
Page 5 of 13

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/l (summer) and 1.8 mg/l (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/l (acute impacts). Due to analytical issues, all TRC values
reported below 50 ug/l are considered compliant with their permit limit.
Describe any proposed changes to ammonia and/or TRC limits for this permit renewal: Wasteload
Allocation (WLA) calculations resulted in a cap of 28 gg/L TRC, which is the same as in the current permit.
Therefore, there are no proposed changes for TRC.
The WLA calculations for ammonia resulted in the same limits as in the current permit. No changes are
proposed from the current permit limits. Table 4 summarizes the NH3-N limit for each flow tier. Figure 1
shows that none of the average monthly and weekly average NH3-N results exceeded the monthly average
and weekly average NH3-N limits even the more stringent limits at permitted flow of 3.0 and 4.5 MGD.
Table 4. NH3-N Limit
Figure 1. Effluent NH3-N data for Q = 2.5 MGD
Mayodan NH, -N for Q= 2.5 MGD
�- MA Limit _ WA Limit
40
35
bA
30
'Z 25
M
Z 20
15 -
•
10 • •
W 5 • •••• t•
Joe. • •
0 ••
al 1/1/2014 7/20/2014 2/5/2015 8/24/2015 3/11/2016 9/27/2016 4/15/2017 11/1/2017
Date
Page 6 of 13
Q=2.5MGD
Q=3.0MGD
Q=4.5MGD
Season
Monthly
Average
Weekly
Average
Monthly
Average
Weekly
Average
Monthly
Avera e
Weekly
Average
Summer
16.0
35.0
14.0
35.0
9.0
27.0
Winter
No Limit
No Limit
No Limit
No Limit
31.5
35.0
Figure 1. Effluent NH3-N data for Q = 2.5 MGD
Mayodan NH, -N for Q= 2.5 MGD
�- MA Limit _ WA Limit
40
35
bA
30
'Z 25
M
Z 20
15 -
•
10 • •
W 5 • •••• t•
Joe. • •
0 ••
al 1/1/2014 7/20/2014 2/5/2015 8/24/2015 3/11/2016 9/27/2016 4/15/2017 11/1/2017
Date
Page 6 of 13

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 April 2014 and
December 2017. 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: Lead at 4.5
MGD
• 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: Arsenic, Cadmium, Total Chromium, Copper, Cyanide, Lead at 2.5 and 3 MGD,
Molybdenum, Nickel, Selenium, Silver, and 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
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.
Toxicity 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.
Page 7 of 13

Describe proposed toxicity test requirement: This is a Major POTW, and a chronic WET limit at 5% (2.5
MGD), 6% (3.0 MGD) and 9% (4.5 MGD) 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/1
Table 5. Mercury Effluent Data Summary- 2.5 MGD
Table 6. Mercury Effluent Data Summary- 3.0 MGD
2014
2015
2016
2017
# of Samples
4
4
4
4
Annual Average Conc. n /L
3.8
4.7
4.5
4.6
Maximum Conc., n L
5.5
11.9
9.9
10.10
TBEL, n /L
47
WQBEL, n /L
244.3
Table 6. Mercury Effluent Data Summary- 3.0 MGD
Table 7. Mercury Effluent Data Summary- 4.5 MGD
2014
2015
2016
2017
# of Samples
4
4
4
4
Annual Average Conc. n /L
3.8
4.7
4.5
4.6
Maximum Conc., n L
5.5
11.9
9.9
1.10
TBEL, n /L
47
WQBEL, n /L
205.5
Table 7. Mercury Effluent Data Summary- 4.5 MGD
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), a mercury minimization plan (MMP) remains the same as in the current permit.
Page 8 of 13
2014
2015
2016
2017
# of Samples
4
4
4
4
Annual Average Conc. n /L
3.8
4.7
4.5
4.6
Maximum Conc., n L
5.5
11.9
9.9
10.10
TBEL, n /L
47
WQBEL, n /L
141.0
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), a mercury minimization plan (MMP) remains the same as in the current permit.
Page 8 of 13

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: NA
If applicable, describe any special actions (HQW or OR W) 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. 010 7(c) (2) (B), 40CFR 122.4 7, and EPA May 2007 Memo: NA
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
9. Antibacksliding Review:
Sections 402(0)(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).
Page 9 of 13

Are any effluent limitations less stringent than previous permit (YES/NO): Yes
If YES, confirm that antibacksliding provisions are not violated: Based on RPA, no monitoring will be
required for Total Chromium, Silver and Copper. In addition, the Total Mercury limit of 47 ng/L annual
average will be removed from the current permit based on the Mercury TMDL evaluation. However, the
Total Mercury will continue to be monitored quarterly as in the current permit.
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(0) 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.
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. Effective December 21, 2020, NPDES regulated facilities will be required to submit
additional NPDES reports electronically. This permit contains the requirements for electronic reporting,
consistent with Federal requirements.
12.Summary of Proposed Permitting Actions:
Table 8. Current Permit Conditions and Proposed Changes 2.5, 3.0 & 4.5 MGD
Parameter
Current Permit
Proposed Change
Basis for Condition/Change
Flow
MA 2.5, 3.0 and 4.5
No change
15A NCAC 213.0505
MGD
BODS
Summer:
No change
TBEL. Secondary treatment
MA 30 mg/1
standards/40 CFR 133 / 15A NCAC
WA 45 mg/1
2B .0406
Winter:
MA 30 mg/l
WA 45 m /l
TSS
MA 30 mg/1
No change
TBEL. Secondary treatment
WA 45 mg/l
standards/40 CFR 133 / 15A NCAC
213 .0406
Page 10 of 13

NH3-N at 2.5
Summer:
No change
WQBEL. Based on protection of
MGD
MA 16.0 mg/l
State WQ criteria (WLA). 15A
WA 35 mg/l
NCAC 2B
Winter
MA No requirement
WA No requirement
NH3-N at 3.0
Summer:
No change
WQBEL. Based on protection of
MGD
MA 14.0 mg/l
State WQ criteria (WLA). 15A
WA 35 mg/l
NCAC 2B
Winter
MA No requirement
WA No requirement
NH3-N at 4.5
Summer:
No change
WQBEL. Based on protection of
MGD
MA 9.0 mg/l
State WQ criteria (WLA). 15A
WA 27 mg/l
NCAC 2B
Winter
MA 31.5 mg/l
WA 35 m /l
Total Residual
DA 28 gg/L
No change
WQBEL. Based on protection of
Chlorine
State WQ criteria (WLA). 15A
NCAC 2B
Fecal coliform
MA 200 /100ml
No change
WQBEL. State WQ standard, 15A
WA 400 /100ml
NCAC 2B
pH
6 — 9 SU
No change
WQBEL. State WQ standard, 15A
NCAC 2B
DO at 2.5 MGD
Monitor 3/week
No change
WQBEL. State WQ standard, 15A
NCAC 2B
DO at 3.0 and 4.5
Monitor Daily
No change
WQBEL. State WQ standard, 15A
MGD
NCAC 2B
Temperature at 2.5
Monitor 3/Week
No change
WQBEL. State WQ standard, 15A
MGD
NCAC 2B
Temperature at 3.0
Monitor Daily
No change
WQBEL. State WQ standard, 15A
and 4.5 MGD
NCAC 2B
Conductivity at
Monitor 3/Week
No change
15A NCAC 2B.0500
2.5 MGD
Conductivity at
Monitor Daily
No change
WQBEL. State WQ standard, 15A
3.0 and 4.5 MGD
NCAC 2B
Total Nitrogen
Monitor Monthly
No change
WQBEL. State WQ standard, 15A
NCAC 2B. 0500
Total Phosphorus
Monitor Monthly
No change
WQBEL. State WQ standard, 15A
NCAC 2B. 0500
Page 11 of 13

Total Chromium at
Monitor Quarterly
Remove monitoring
No reasonable potential (RP) found
2.5 MGD
in RPA and less than Cr VI
Total Chromium at
MA 856 µg/L
Remove effluent
No reasonable potential (RP) found
3.0 MGD
limitation and
in RPA and less than Cr VI
DM 14,500 µg/L
monitoring
Total Chromium at
MA 587 µg/L
Remove effluent
No reasonable potential (RP) found
4.5 MGD
limitation and
in RPA and less than Cr VI
DM 10,000 µg/L
monitoring
Total Mercury
AA 47 ng/L
Remove effluent
Mercury TMDL Evaluation
limitation and
monitoring
Total Silver
Monitor Quarterly
Remove monitoring
No reasonable potential (RP) found
in RPA
Total Copper
Monitor Quarterly
Remove monitoring
No reasonable potential (RP) found
in RPA
Lead
No Requirement
Monitor Quarterly at
Reasonable potential (RP) found in
4.5 MGD
RPA
Total Hardness
No Requirement
Add effluent and
Hardness -dependent dissolved
upstream Quarterly
metals water quality standards
Monitoring
approved in 2016
Toxicity Test
Monitor Quarterly
No change
WQBEL. No toxics in toxic
amounts. 15A NCAC 2B
Effluent Pollutant
Monitor and Report
Three times per permit
40 CFR 122
Scan
cycle
Electronic
No requirement
Add Electronic
In accordance with EPA Electronic
Reporting
Reporting Special
Reporting Rule 2015.
Condition
MGD — Million gallons per day, MA - Monthly Average, WA — Weekly Average, DM — Daily Max, AA -
Annual Average
13. Public Notice Schedule:
Permit to Public Notice: 05/01/2018
Per 15A NCAC 2H .0109 & .0 111, 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.
Page 12 of 13

14. 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
NC Wildlife Resources Commission (WRC) did make comments on the draft renewal permit due to the
presence of rare, threatened and endangered aquatic species, including mussels and fish. Specifically they
requested that we encourage the permittee to consider switching disinfection to UV or Ozone instead of
Chlorine, and that we investigate developing site specific limits for ammonia -nitrogen.
In response, we did agree to add language to the permit issuance cover page discussing the WRC concerns
and to strongly request the permittee to consider UV or other alternate to chlorination, and to keep working
on controlling ammonia -nitrogen discharges. It was pointed out that the recent TRC analysis have all been
below 50 µg/L, and the facility has passed all WET tests. The existing NH3-N data was reviewed and in -
stream concentrations were calculated from DMR data using 7Q10 dilution and the Division's standard
background ammonia -N concentration of 0.22 mg/ L. The results showed mostly background to slightly
above background ammonia -N of 0. 22 - 0.25 mg/ L. The highest in -stream concentration was 0.34 mg/ L
in July 2016. See attached Ammonia -N predicted In -stream Concentrations, Mayo WWTP January
2015 - February 2018.
15. Fact Sheet Attachments (if applicable):
RPA Spreadsheet Summary
Dissolved Metals Implementation/Freshwater or Saltwater
Page 13 of 13

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
WWTP/WTP Class
NPDES Permit
Outfall
Flow, Qw (MGD)
Receiving Stream
HUC Number
Stream Class
]Apply WS Hardness WQC
7Q1Os (cfs)
7011 Ow (cfs)
30Q2 (cfs)
QA (cfs)
1 Q1 Os (cfs)
Effluent Hardness_
Upstream Hardness_
Combined Hardness Chronic_
Combined Hardness Acute
Data Source(s)
❑CHECK TO APPLY MODEL
Town of Mayodan WWTP
III
NCO021873
001
2.500
Mayo River
0301010304
C
75.00
131.00
150.00
362.00
61.34
64.74 mg/L (Avg)
-------------------
36.26 mg/L (Avg)
-------------------
37.66 mg/L
-------------------
37.95 mg/L
REQUIRED DATA ENTRY
Par01
Par02
Par03
Par04
Par05
Par06111111
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
0.8041
FW
4.6638
ug/L
Chlorides
Aquatic Life
NC
230
FW
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
164.6657
FW
1273.9479
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
11.1837
FW
15.5177
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
4.6574
FW
120.5551
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5 ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
52.6525
FW
477.1704
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
0.6077
ug/L
Zinc
Aquatic Life
NC
179.3216
FW
179.0388
ug/L
Bromoform
Human Health
C
120
HH
pg/L
Dichlorobromomethane
Human Health
C
27
HH
pg/L
RPA_Mayodan_NCO021873_Q 2.5 mgd_More metals, input
6/27/2018

RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, input
6/27/2018

REASONABLE POTENTIAL ANALYSIS
1
Effluent Hardness
Use "PASTE SPECIAL
Values" then "COPY"
H2
Upstream Hardness
Use "PASTE SPECIAL
Values" then "COPY"
Par01 & Par02
Arsenic
. Maximum data
. Maximum data
points = 58
points = 58
Date
Data
BDL=1/2DL
Results
Date
Data
BDL=1/2DL
Results
Date Data
BDL=1/2DL
1 9/9/2014
69
69
Std Dev.
20.6917
1
6/21/2016
40
40
Std Dev.
15.3601
1
4/2/2014 <
5
2.5
2 12/8/2015
44
44
Mean
64.7368
2
7/5/2016
75
75
Mean
36.2581
2
6/4/2014 <
5
2.5
3 3/15/2016
57
57
C.V.
0.3196
3
7/19/2016
52
52
C.V.
0.4236
3
9/10/2014 <
5
2.5
4 6/21/2016
68
68
n
38
4
8/2/2016
44
44
n
31
4
12/2/2014 <
5
2.5
5 7/5/2016
135
135
10th Per value
44.00 mg/L
5
8/16/2016
78
78
10th Per value
20.00 mg/L
5
3/4/2015 <
5
2.5
6 7/19/2016
84
84
Average Value
64.74 mg/L
6
9/6/2016
41
41
Average Value
36.26 mg/L
6
6/3/2015 <
5
2.5
7 8/2/2016
85
85
Max. Value
135.00 mg/L
7
9/20/2016
60
60
Max. Value
78.00 mg/L
7
9/2/2015 <
5
2.5
8 8/16/2016
78
78
8
10/4/2016
53
53
8
12/9/2015 <
5
2.5
9 9/6/2016
90
90
9
10/18/2016
32
32
9
3/9/2016 <
5
2.5
10 9/20/2016
104
104
10
12/13/2016
32
32
10
6/8/2016 <
5
2.5
11 10/4/2016
85
85
11
12/20/2016
36
36
11
9/7/2016 <
5
2.5
12 10/18/2016
68
68
12
1/10/2017
33
33
12
12/14/2016 <
5
2.5
13 12/13/2016
68
68
13
1/17/2017
36
36
13
3/8/2017 <
5
2.5
14 12/20/2016
92
92
14
1/31/2017
20
20
14
6/14/2017 <
5
2.5
15 1/10/2017
82
82
15
2/28/2017
20
20
15
9/13/2017 <
5
2.5
16 1/17/2017
76
76
16
3/7/2017
36
36
16
12/6/2017 <
5
2.5
17 1/31/2017
65
65
17
3/21/2017
24
24
17
18 2/28/2017
56
56
18
4/4/2017
20
20
18
19 3/7/2017
44
44
19
4/19/2017
28
28
19
20 3/21/2017
44
44
20
5/2/2017
24
24
20
21 4/5/2017
48
48
21
5/16/2017
56
56
21
22 4/19/2017
60
60
22
9/5/2017
20
20
22
23 5/2/2017
44
44
23
9/19/2017
20
20
23
24 5/16/2017
84
84
24
10/4/2017
28
28
24
25 6/6/2017
48
48
25
11/7/2017
24
24
25
26 6/20/2017
29
29
26
11/21/2017
28
28
26
27 8/1/2017
63
63
27
12/6/2017
28
28
27
28 8/16/2017
63
63
28
1/2/2018
24
24
28
29 9/5/2017
56
56
29
1/16/2018
36
36
29
30 9/19/2017
48
48
30
2/7/2018
36
36
30
31 10/4/2017
64
64
31
2/20/2018
40
40
31
32 11/7/2017
40
40
32
32
33 11/21/2017
52
52
33
33
34 12/6/2017
52
52
34
34
35 1/2/2018
60
60
35
35
36 1/16/2018
55
55
36
36
37 2/7/2018
60
60
37
37
38 2/20/2018
40
40
38
38
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
3- 6/27/2018

Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018
Use"PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58
Results
Std Dev.
0.0000
Mean
2.5000
C.V.
0.0000
n
16
Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018

Cadmium
Date Data BDL=1/2DL Results
1 4/2/2014 < 1 0.5 Std Dev.
2 6/4/2014 < 1 0.5 Mean
3 9/10/2014 < 1 0.5 C.V.
4 12/2/2014 < 1 0.5 n
5 3/4/2015 < 1 0.5
6 6/3/2015 < 1 0.5 Mult Factor =
7 9/2/2015 < 1 0.5 Max. Value
8 12/9/2015 < 1 0.5 Max. Pred Cw
9 3/9/2016 < 1 0.5
10 6/8/2016 < 1 0.5
11 9/7/2016 < 1 0.5
12 12/14/2016 < 1 0.5
13 3/8/2017 < 1 0.5
14 6/14/2017 < 1 0.5
15 9/13/2017 < 1 0.5
16 12/6/2017 < 1 0.5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Pdr10
Values" then "COPY"
. Maximum data
points = 58
0.5000
0.0000
16
1.00
0.500 ug/L
0.500 ug/L
Chromium, Total
Date
Data
1
3/31/2014
<
2
4/2/2014
<
3
6/4/2014
<
4
6/10/2014
<
5
9/10/2014
<
6
12/2/2014
<
7
3/4/2015
<
8
6/3/2015
<
9
9/2/2015
<
10
12/9/2015
<
11
3/9/2016
<
12
3/15/2016
<
13
6/8/2016
<
14
9/7/2016
<
15
12/14/2016
<
16
3/8/2017
<
17
6/14/2017
<
18
6/20/2017
<
19
9/13/2017
<
20
12/6/2017
<
21
33
22
35
23
36
24
38
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Chromium, Total
Date Data
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
9
5
2.5
Mult Factor =
5
2.5
Max. Value
5
2.5
Max. Pred Cw
5
2.5
15
5
2.5
6/14/2017
5
2.5
18
5
2.5
12/6/2017
5
2.5
21
5
2.5
5
2.5
255
5
2.5
5
2.5
28
5
2.5
5
2.5
31
5
2.5
5 -
Use "PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58 r
2.5000
0.0000
20
1.00
2.5 pg/L
2.5 pg/L
Copper
BDL=1/2DL
7 7
6 6
8 8
10 10
11 11
9 9
10 10
3 3
5 5
6 6
5 5
5 5
9 9
9 9
6 6
5 5
6 6
10 10
11 11
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018
Date Data
1
3/31/2014
2
4/2/2014
3
6/4/2014
4
6/10/2014
5
9/10/2014
6
12/2/2014
7
3/4/2015
8
6/3/2015
9
9/2/2015
10
12/9/2015
11
3/9/2016
12
6/8/2016
13
9/7/2016
14
12/14/2016
15
3/8/2017
16
6/14/2017
17
6/20/2017
18
9/13/2017
19
12/6/2017
20
21
22
23
24
L
255
26
27
28
29
30
31
32
33
34
35
36
37
38
Copper
BDL=1/2DL
7 7
6 6
8 8
10 10
11 11
9 9
10 10
3 3
5 5
6 6
5 5
5 5
9 9
9 9
6 6
5 5
6 6
10 10
11 11
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par12 Use "PASTE SPECIAL Par14
Values" then "COPY" Cyanide Values" then "COPY"
. Maximum data . Maximum data
points = 58 points = 58
Results
Date
Std Dev.
2.4110
Mean
7.4211
C.V.
0.3249
n
19
MultFactor= 1.21
Max. Value 11.00 ug/L
Max. Fred Cw 13.31 ug/L
5.00
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
6 -
Date
1 4/2/2014 <
2 6/4/2014 <
3 9/10/2014 <
4 12/2/2014 <
5 3/4/2015 <
6 6/3/2015 <
7 9/2/2015 <
8 12/9/2015 <
9 3/9/2016 <
10 6/8/2016
11 9/7/2016
12 12/14/2016
13 3/8/2017 <
14 6/14/2017 <
15 9/13/2017
16 12/6/2017 <
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Lead
Date
Data
Results
BDL=1/2DL
Results
1
4/2/2014
<
5
5
Std Dev.
2
6/4/2014
<
5
5
Mean
3
9/10/2014
<
5
5
C.V.
4
12/2/2014
<
5
5
n
5
3/4/2015
<
5
5
6
6/3/2015
<
5
5
MultFactor=
7
9/2/2015
<
5
5
Max. Value
8
12/9/2015
<
5
5
Max. Fred Cw
9
3/9/2016
<
5
5
10
6/8/2016
<
5
5
11
9/7/2016
<
5
5
12
12/14/2016
<
5
5
13
3/8/2017
<
5
5
14
6/14/2017
<
5
5
15
9/13/2017
<
5
5
16
12/6/2017
<
5
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
5.00
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
6 -
Date
1 4/2/2014 <
2 6/4/2014 <
3 9/10/2014 <
4 12/2/2014 <
5 3/4/2015 <
6 6/3/2015 <
7 9/2/2015 <
8 12/9/2015 <
9 3/9/2016 <
10 6/8/2016
11 9/7/2016
12 12/14/2016
13 3/8/2017 <
14 6/14/2017 <
15 9/13/2017
16 12/6/2017 <
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Lead
Date Da
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
6/3/2015
5 2.5
MultFactor=
5 2.5
Max. Value
5 2.5
Max. Fred Cw
5 2.5
6/8/2016 <
6 6
9/7/2016
20 20
12/13/2016
12 12
3/8/2017 <
5 2.5
6/14/2017
5 2.5
9/13/2017
10 10
12/6/2017
5 2.5
Use "PASTE SPECIAL Par15
Values" then "COPY"
. Maximum data
points = 58
4.8750
1.0253
16
1.80
20.000 ug/L
36.000 ug/L
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018
Date Da
1
4/2/2014
2
6/3/2014
3
9/10/2014
4
12/3/2014
5
3/4/2015
6
6/3/2015
7
9/2/2015
8
12/9/2015
9
3/9/2016
10
6/8/2016 <
11
9/7/2016
12
12/13/2016
13
3/8/2017 <
14
6/14/2017
15
9/13/2017
16
12/6/2017
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018

Mercury
to
BDL=1/2DL
Results
1.1
1.1
Std Dev.
5.5
5.5
Mean
5.2
5.2
C.V.
3.4
3.4
n
3.3
3.3
Mean
1.4
1.4
Mult Factor =
11.9
11.9
Max. Value
2.3
2.3
Max. Pred Cw
3.5
3.5
n
1
0.5
<
9.9
9.9
4.1
4.1
<
1
0.5
Mult Factor =
3.4
3.4
<
10.1
10.1
Max. Value
4.4
4.4
<
REASONABLE POTENTIAL ANALYSIS
Par16 Par17 & Par18
Use "PASTE SPECIAL Use "PASTE SPECIAL
Values" then "COPY" Molybdenum Values" then "COPY" Nickel
. Maximum data . Maximum data
points = 58 points = 58
4.4063
0.7855
16
1.62
11.9 ng/L
19.3 ng/L
7 -
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Pred Cw
9
3/9/2016
<
10
5
10
6/8/2016
<
10
5
11
9/7/2016
<
10
5
12
12/14/2016
<
10
5
13
3/8/2017
<
10
5
14
6/14/2017
<
10
5
15
9/13/2017
<
10
5
16
12/6/2017
<
10
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
7 -
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Use "PASTE SF
Values" then "i
Maximum <
points = 5
5.3125
0.2353
16
1.17
10.0
11.7
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Pred Cw
9
3/9/2016
<
10
5
10
6/8/2016
<
10
5
11
9/7/2016
<
10
5
12
12/14/2016
<
10
5
13
3/8/2017
<
10
5
14
6/14/2017
<
10
5
15
9/13/2017
10
10
16
12/6/2017
<
10
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Use "PASTE SF
Values" then "i
Maximum <
points = 5
5.3125
0.2353
16
1.17
10.0
11.7
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018

Par19
Selenium
Date Data BDL=1/2DL Results
1 4/2/2014 < 10 5 Std Dev.
2 6/4/2014 < 10 5 Mean
3 9/10/2014 < 10 5 C.V.
4 12/2/2014 < 10 5 n
5 3/4/2015 < 10 5
6 6/3/2015 < 10 5 Mult Factor =
Ng/L 7 9/2/2015 < 10 5 Max. Value
Ng/L 8 12/9/2015 < 10 5 Max. Pred Cw
9 3/9/2016 < 10 5
10 6/8/2016 < 10 5
11 9/7/2016 < 10 5
12 12/14/2016 < 10 5
13 3/8/2017 < 10 5
14 6/14/2017 < 10 5
15 9/13/2017 < 10 5
16 12/6/2017 < 10 5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Paf20
Values" then "COPY" Silver
. Maximum data
points = 58
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Date
Data
BDL=1/2DL
Results
1 3/31/2014
<
10
5
Std Dev.
2 4/2/2014
<
1
0.5
Mean
3 6/4/2014
<
1
0.5
C.V.
4 6/10/2014
<
1
0.5
n
5 9/10/2014
<
1
0.5
9/2/2015
6 12/2/2014
<
1
0.5
Mult Factor =
7 3/4/2015
<
1
0.5
Max. Value
8 6/3/2015
<
1
0.5
Max. Pred Cw
9 9/2/2015
<
1
0.5
12/14/2016
10 12/9/2015
<
1
0.5
26
11 3/9/2016
<
1
0.5
52
12 6/8/2016
<
1
0.5
16
13 9/7/2016
<
1
0.5
14 12/14/2016
<
1
0.5
15 3/8/2017
<
1
0.5
16 6/14/2017
<
1
0.5
21
17 6/20/2017
<
1
0.5
18 9/13/2017
<
1
0.5
19 12/6/2017
<
1
0.5
20
26
21
27
22
23
28
24
L
29
255
31
26
32
27
33
28
34
29
36
30
37
31
38
32
33
34
35
36
37
38
8 -
Use "PASTE SPECIAL Par21
Values" then "COPY"
. Maximum data
points = 58
0.7368
1.4011
19
1.85
5.000 ug/L
9.250 ug/L
Zinc
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018
Date Data
BDL=1/2DL
1
4/2/2014
51
51
2
6/4/2014
59
59
3
9/10/2014
72
72
4
12/2/2014
55
55
5
3/4/2015
81
81
6
6/3/2015
37
37
7
9/2/2015
71
71
8
12/9/2015
49
49
9
3/9/2016
57
57
10
6/8/2016
23
23
11
9/7/2016
63
63
12
12/14/2016
71
71
13
3/8/2017
26
26
14
6/14/2017
52
52
15
9/13/2017
48
48
16
12/6/2017
77
77
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
6/27/2018

REASONABLE POTENTIAL ANALYSIS
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
9- 6/27/2018
Par22
Par23
Use "PASTE SPECIAL
Use "PASTE SPECIAL
Use "PASTE SPECIAL
Values" then "COPY"
Bromoform
Values" then "COPY"
Dlchlorobro171omethane
Values" then "COPY"
. Maximum data
. Maximum data
. Maximum data
points = 58
points = 58
points = 58
Results
Date Data
BDL=1/2DL
Results
Date
Data BDL=1/2DL
Results
Std Dev.
17.0000
1
9/9/2014
51.6 51.6
Std Dev.
26.4426
1
9/9/2014
15.2 15.2
Std Dev.
5.8312
Mean
55.7500
2
12/8/2015
5.8 5.8
Mean
21.0667
2
12/8/2015
15.2 15.2
Mean
11.8333
C.V.
0.3049
3
3/15/2016
5.8 5.8
C.V. (default)
0.6000
3
3/15/2016
5.1 5.1
C.V. (default)
0.6000
n
16
4
n
3
4
n
3
5
5
MultFactor=
1.23
6
MultFactor=
3.00
6
MultFactor=
3.00
Max. Value
81.0 ug/L
7
Max. Value
51.600000 pg/L
7
Max. Value
15.200000 pg/L
Max. Fred Cw
99.6 ug/L
8
Max. Fred Cw
154.800000 pg/L
8
Max. Fred Cw
45.600000 pg/L
9
9
10
10
11
11
12
12
13
13
14
14
15
15
16
16
17
17
18
18
19
19
20
20
21
21
22
22
23
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
RPA_Mayodan_NC0021873_Q 2.5 mgd_More metals, data
9- 6/27/2018

Town of Mayodan WWTP -
NC0021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM
Qw (MGD) =
2.5000
1Q10S (cfs) =
61.34
7Q10S (cfs) =
75.00
7Q10W (cfs) =
131.00
30Q2 (cfs) =
150.00
Avg. Stream Flow, QA (cfs) =
362.00
Receiving Stream: Mayo River HUC 0301010304
DATA POINTS = 58
WWTP/WTP Class: III
IWC% @ 1Q10S =
5.941884536
IWC% @ 7Q10S =
4.912836767
IWC% @ 7Q10W =
2.873030584
1WC% @ 30Q2 =
2.518277823
IW%C @ QA =
1.059104886
Stream Class:
C
Outfall 001
Qw = 2.5 MGD
COMBINED HARDNESS (me/L)
Acute = 37.95 mg/L
Chronic = 37.66 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
J
a
Applied
Chronic Acute
n # Det. Max Pred Cw Allowable Cw
Standa
Acute (FW): 5,722.1
No RP, Predicted Max < 50% of Allowable Cw - No
Arsenic
C
150 FW(7Q10s) 340
ug/L
Monitoring required
16 0
2.5
------------------------------------
Chronic (FW): 3,053.2
All values less than 5 ug/L
Max MDL =-5
Arsenic
C
10 HH/WS(Qavg)
ug/L
NO DETECTS
Chronic (HH): 944.2
_ --------------------------
____________Arsenic
All values less than 5 ug/L
Max MDL = 5
Acute: 78.491
No RP, Predicted Max < 50% of Allowable Cw - No
Cadmium
NC
0.8041 FW(7Q10s) 4.6638
ug/L
16 0
0.500
Monitoring required
- - -----------------------------
Chronic: 16.366
no detect, all values less than 1 ug/L
NO DETECTS
Max MDL = 1
Acute: 269.3
Chromium VI
NC
11 FW(7Q10s) 16
gg/L
0 0
N/A
Chronic: -----223.9--
---------------------------
Chromium, Total
NC
gg/L
20 0
2.5
Max reported value = 2.5
All values less than 5 ug/L & < Cr IV
NO DETECTS
Max MDL = 5
Acute: 261.16
No RP, Predicted Max < 50% of Allowable Cw - No
Copper
NC
11.1837 FW(7Q10s) 15.5177
ug/L
19 19
13.31
Monitoring required
Chronic: 227.64
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 370.3
No RP, Predicted Max < 50% of Allowable Cw - No
Cyanide
NC
5 FW(7Q10s) 22
10
ug/L
16 0
5.0
Monitoring required
---------------------------------------------
Chronic: 101.8
All values less than 5 ug/L
NO DETECTS
Max MDL = 10
Acute: 2,028.904
No RP, Predicted Max < 50% of Allowable Cw - No
Lead
NC
4.6574 FW(7Q10s) 120.5551
ug/L
16 4
36.000
Monitoring required
Chronic: 94.800
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Mercury
NC
12 FW(7Q10s)
0.5
ng/L
16 14
19.3
Chronic: 244.3
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Molybdenum
NC
2000 HH(7Q10s)
ug/L
16 0
5.0
Chronic: 40,709.7
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL = 10
Monitoring required
RPA_ Mayodan_NC0021873_Q 2.5 mgd_More metals, rpa
Page 10 of 12 6/27/2018

Town of Mayodan WWTP - Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 2.5 MGD
RPA_ Mayodan_NC0021873_Q 2.5 mgd_More metals, rpa
Page 11 of 12 6/27/2018
Acute (FW): 8,030.6
No RP, Predicted Max < 50% of Allowable Cw - No
Nickel
NC
52.6525 FW(7Q10s) 477.1704
gg/L
---------------------------------------------
Monitoring required
16 1
11.7
Chronic (FW): 1,071.7
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
------------------------------
Monitoring required
Nickel
NC
25.0000 WS(7Q10s)
µg /L
Chronic (WS): 508.9
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 942.5
No RP, Predicted Max < 50% of Allowable Cw - No
Selenium
NC
5 FW(7Q10s) 56
ug/L
16 0
5.0
Monitoring required
Chronic: 101.8
All values less than 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 10.227
Silver
NC
0.06 FW(7Q10s) 0.6077
ug/L
19 0
9.250
Chronic: 1.221
All values < 1 ug/L with one < 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 3,013.2
No RP, Predicted Max < 50% of Allowable Cw - No
Zinc
NC
179.3216 FW(7Q10s) 179.0388
ug/L
16 16
99.6
Monitoring required
Chronic: 3,650.1
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Bromoform
c
120 HH(Qavg)
gg/L
3 3
154.80000
Note: n:5 9
C.V. (default)
Chronic: 11330.32258
No RP, Predicted Max < 50% of Allowable Cw -No
Limited data set
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Dichlorobromomethane c
27 HH(Qavg)
gg/L
33
45.60000
Note: n <_ 9
C.V. (default)
Chronic: 2549.32258 No RP, Predicted Max < 50% of Allowable Cw - No
Limited data set
INo value > Allowable Cw Monitoring required
RPA_ Mayodan_NC0021873_Q 2.5 mgd_More metals, rpa
Page 11 of 12 6/27/2018

Date: 6/27/2018
Enter data onto "Table 1" under the Input Sheet and enter
"Effluent Hardness" under the Data Sheet.
In accordance with 40 CFR 122.45 (c), permits are, have and
must be written as total metals.
This calculator has been inserted into the RPA to calculate Total
Metal allowable allocations once Table 1 has been completed
(Input Sheet) and Effluent hardness has been entered (Data
Sheet).
1) Following the spreadsheet from left to right. First
the allowable allocations for the dissolved metals will
appear for all the metals listed once Table 1 is complete and
effluent hardness entered. Use a default value of 25 mg/L if
no hardness data is available. Second, the
Dissolved Metal allocations are divided by the Translators to
determine the Total Metals that can be allocated to the
Permittee. These Total Metals values are automatically
inserted into Table 2 and are the allowable Total Metal
allocations determined for the Permittee prior to allowing
for dilution. See Input sheet Table 2. The final acute and
chronic values shown under the RPA sheet are the Total
Metal values listed in Table 2 divided by the acute and
chronic IWC, respectively.
2) The Translators used in the freshwater RPA are the Partition
Coefficients published by US EPA in 1984. They are TSS
dependent equations and can be found listed with the WQS
hardness dependent equations under the sheet labeled
Equations. A fixed TSS value of 30 mg/L is used to calculate
the Translator values.
3) Pretreatment Facilities— PERCS will need a copy of the
Dissolved to Total Metal Calculator spreadsheet and the
RPA sheet along with the Final Permit. Pretreatment
Facilities are required to renew their Headwords Analysis
after renewal of their permits. Since all their metal
allocations are likely to change PERCS needs to see any new
metal permit limits and the allowable allocations for the
dissolved metals to assess Maximum Allowable Headworks
Loading (MAHL) numbers for each metal based on the
Combined Hardness values used in the permit writers RPA
calculations.
4) For Cadmium, Lead, Nickel, Chromium and Beryllium, if all
the effluent sampling data for the last three to five years
shows the pollutant at concentrations less than the Practical
Quantitative Level (PQL), it is not likely a limit or monitoring
will be put in the permit. However, if the estimated NPDES
permit limit is less than the Practical Quantitative Limit
(particularly, Cadmium and Lead) and the pollutant is
believed to be present, to assess compliance with the new
standards and for future permit limit development,
monitoring for the pollutant will be required. If the facility is
monitoring for the pollutant in its Pretreatment LTMP, no
monitoring is needed in the permit.
5) For monitoring and compliance purposes if Total Chromium
'Y: Town of Mayodan WWTP Outfall 001
PERMIT: NCO021873 Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
Recelving Recewl" 9
Stream Stream
su mer 7010
Hec. Jtream
1010
NHUtJ
Flow Limn
Total Suspende0
Solids
-Fixed Value-
ComDinetl
Hardness
chronic
ComDinetl
Hardness
Acute
Instream
Wastexater
ConranVatlon
Instream Emu
Wastewater Upstream Hardness
Hartlness
ConcenVaton Averege
Average
7010(CFS) (MGD)
MGD
MGD
(mg/L)
(mg/L)
(mg/L)
(Chronic)
(Acute)' (mgt) (mglL)
75.0000 1 48.3871
39.5742
2.5000
10
37.657
37.950
4.9128
5.9419 36.2580645 64.73684
Upstream Hard Avg (mg/L) = 36.25806
EFF Hard Avg (mg/L) = 64.73684
Dissolved Metals CriteriaUS
EPA
III Metal Criteria
Tela) Metal=
COMMENTS (Identify parameters to PERCS Branch to maintain in facility's LTMP/STMP):
after applying hartlness
PARAMETER uaron
Translators -using
Default Partition
Dissolved Mesa+Tansia.r
Chronic Acute
Coefficients
Chronic
I Acute
0.202 164.67
1.000 11.00
N/A
0.348 11.18
0.184 4.66
0.432 52.65
25
1.000 0.06
0.2881 179.32
=dissolved metal standard.5ee 15A NCAC 026.0211 for more information.
= hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
= based upon measurement of total recaveable metal. See 15A NCAC 02B.0211 far mare informadon.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Toml Recoverable metal standard.
The Human Health standard for Arsenic is 30 pg/L which is Total Recoverable metal standard.
ACA H 37.95024
ACCH 37.65718

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
WWTP/WTP Class
NPDES Permit
Outfall
Flow, Qw (MGD)
Receiving Stream
HUC Number
Stream Class
]Apply WS Hardness WQC
7Q1Os (cfs)
7011 Ow (cfs)
30Q2 (cfs)
QA (cfs)
1 Q1 Os (cfs)
Effluent Hardness_
Upstream Hardness_
Combined Hardness Chronic_
Combined Hardness Acute
Data Source(s)
❑CHECK TO APPLY MODEL
Town of Mayodan WWTP
IV
NCO021873
001
3.000
Mayo River
0301010304
C
75.00
131.00
150.00
362.00
61.34
64.74 mg/L (Avg)
-------------------
36.26 mg/L (Avg)
-------------------
37.92 mg/L
-------------------
38.26 mg/L
REQUIRED DATA ENTRY
Par01
Par02
Par03
Par04
Par05
Par06111111
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
0.8083
FW
4.6975
ug/L
Chlorides
Aquatic Life
NC
230
FW
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
165.6087
FW
1282.5903
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
11.2505
FW
15.6388
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
4.6938
FW
121.6715
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5 ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
52.9640
FW
480.5146
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
0.6164
ug/L
Zinc
Aquatic Life
NC
180.3842
FW
180.2955
ug/L
Bromoform
Human Health
C
120
HH
pg/L
Dichlorobromomethane
Human Health
C
27
HH
pg/L
RPA_Mayodan_NCO021873_Q 3 mgd_More metals, input
6/27/2018

RPA_Mayodan_NC0021873_Q 3 mgd_More metals, input
6/27/2018

REASONABLE POTENTIAL ANALYSIS
1
Effluent Hardness
Use "PASTE SPECIAL
Values" then "COPY"
H2
Upstream Hardness
Use "PASTE SPECIAL
Values" then "COPY"
Par01 & Par02
Arsenic
. Maximum data
. Maximum data
points = 58
points = 58
Date
Data
BDL=1/2DL
Results
Date
Data
BDL=1/2DL
Results
Date Data
BDL=1/2DL
1 9/9/2014
69
69
Std Dev.
20.6917
1
6/21/2016
40
40
Std Dev.
15.3601
1
4/2/2014 <
5
2.5
2 12/8/2015
44
44
Mean
64.7368
2
7/5/2016
75
75
Mean
36.2581
2
6/4/2014 <
5
2.5
3 3/15/2016
57
57
C.V.
0.3196
3
7/19/2016
52
52
C.V.
0.4236
3
9/10/2014 <
5
2.5
4 6/21/2016
68
68
n
38
4
8/2/2016
44
44
n
31
4
12/2/2014 <
5
2.5
5 7/5/2016
135
135
10th Per value
44.00 mg/L
5
8/16/2016
78
78
10th Per value
20.00 mg/L
5
3/4/2015 <
5
2.5
6 7/19/2016
84
84
Average Value
64.74 mg/L
6
9/6/2016
41
41
Average Value
36.26 mg/L
6
6/3/2015 <
5
2.5
7 8/2/2016
85
85
Max. Value
135.00 mg/L
7
9/20/2016
60
60
Max. Value
78.00 mg/L
7
9/2/2015 <
5
2.5
8 8/16/2016
78
78
8
10/4/2016
53
53
8
12/9/2015 <
5
2.5
9 9/6/2016
90
90
9
10/18/2016
32
32
9
3/9/2016 <
5
2.5
10 9/20/2016
104
104
10
12/13/2016
32
32
10
6/8/2016 <
5
2.5
11 10/4/2016
85
85
11
12/20/2016
36
36
11
9/7/2016 <
5
2.5
12 10/18/2016
68
68
12
1/10/2017
33
33
12
12/14/2016 <
5
2.5
13 12/13/2016
68
68
13
1/17/2017
36
36
13
3/8/2017 <
5
2.5
14 12/20/2016
92
92
14
1/31/2017
20
20
14
6/14/2017 <
5
2.5
15 1/10/2017
82
82
15
2/28/2017
20
20
15
9/13/2017 <
5
2.5
16 1/17/2017
76
76
16
3/7/2017
36
36
16
12/6/2017 <
5
2.5
17 1/31/2017
65
65
17
3/21/2017
24
24
17
18 2/28/2017
56
56
18
4/4/2017
20
20
18
19 3/7/2017
44
44
19
4/19/2017
28
28
19
20 3/21/2017
44
44
20
5/2/2017
24
24
20
21 4/5/2017
48
48
21
5/16/2017
56
56
21
22 4/19/2017
60
60
22
9/5/2017
20
20
22
23 5/2/2017
44
44
23
9/19/2017
20
20
23
24 5/16/2017
84
84
24
10/4/2017
28
28
24
25 6/6/2017
48
48
25
11/7/2017
24
24
25
26 6/20/2017
29
29
26
11/21/2017
28
28
26
27 8/1/2017
63
63
27
12/6/2017
28
28
27
28 8/16/2017
63
63
28
1/2/2018
24
24
28
29 9/5/2017
56
56
29
1/16/2018
36
36
29
30 9/19/2017
48
48
30
2/7/2018
36
36
30
31 10/4/2017
64
64
31
2/20/2018
40
40
31
32 11/7/2017
40
40
32
32
33 11/21/2017
52
52
33
33
34 12/6/2017
52
52
34
34
35 1/2/2018
60
60
35
35
36 1/16/2018
55
55
36
36
37 2/7/2018
60
60
37
37
38 2/20/2018
40
40
38
38
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
3- 6/27/2018

Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018
Use"PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58
Results
Std Dev.
0.0000
Mean
2.5000
C.V.
0.0000
n
16
Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

Cadmium
Date Data BDL=1/2DL Results
1 4/2/2014 < 1 0.5 Std Dev.
2 6/4/2014 < 1 0.5 Mean
3 9/10/2014 < 1 0.5 C.V.
4 12/2/2014 < 1 0.5 n
5 3/4/2015 < 1 0.5
6 6/3/2015 < 1 0.5 Mult Factor =
7 9/2/2015 < 1 0.5 Max. Value
8 12/9/2015 < 1 0.5 Max. Pred Cw
9 3/9/2016 < 1 0.5
10 6/8/2016 < 1 0.5
11 9/7/2016 < 1 0.5
12 12/14/2016 < 1 0.5
13 3/8/2017 < 1 0.5
14 6/14/2017 < 1 0.5
15 9/13/2017 < 1 0.5
16 12/6/2017 < 1 0.5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Pdr09
Values" then "COPY"
. Maximum data
points = 58
0.5000
0.0000
16
1.00
0.500 ug/L
0.500 ug/L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Chromium VI
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
5 -
Use "PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58 r
NO DATA
NO DATA
0
N/A
N/A pg/L
N/A pg/L
Chromium, Tot;
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
1
3/31/2014
<
5
2.5
2
4/2/2014
<
5
2.5
3
6/4/2014
<
5
2.5
4
6/10/2014
<
5
2.5
5
9/10/2014
<
5
2.5
6
12/2/2014
<
5
2.5
7
3/4/2015
<
5
2.5
8
6/3/2015
<
5
2.5
9
9/2/2015
<
5
2.5
10
12/9/2015
<
5
2.5
11
3/9/2016
<
5
2.5
12
3/15/2016
<
5
2.5
13
6/8/2016
<
5
2.5
14
9/7/2016
<
5
2.5
15
12/14/2016
<
5
2.5
16
3/8/2017
<
5
2.5
17
6/14/2017
<
5
2.5
18
6/20/2017
<
5
2.5
19
9/13/2017
<
5
2.5
20
12/6/2017
<
5
2.5
21
22
23
24
250
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

al
Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Pall Use "PASTE SPECIAL Par12
Values" then "COPY" Copper Values" then "COPY"
. Maximum data . Maximum data
points = 58 points = 58
2.5000
0.0000
20
1.00
2.5 pg/L
2.5 pg/L
7.4211
0.3249
19
1.21
11.00 ug/L
13.31 ug/L
6 -
Date Data
Data
BDL=1/2DL
Results
1
3/31/2014
7
7
Std Dev.
2
4/2/2014
6
6
Mean
3
6/4/2014
8
8
C.V.
4
6/10/2014
10
10
n
5
9/10/2014
11
11
<
6
12/2/2014
9
9
Mult Factor =
7
3/4/2015
10
10
Max. Value
8
6/3/2015
3
3
Max. Pred Cw
9
9/2/2015
5
5
12/6/2017
10
12/9/2015
6
6
18
11
3/9/2016
5
5
12
6/8/2016
5
5
13
9/7/2016
9
9
23
14
12/14/2016
9
9
15
3/8/2017
6
6
16
6/14/2017
5
5
28
17
6/20/2017
6
6
18
9/13/2017
10
10
19
12/6/2017
11
11
33
20
34
21
36
22
37
38
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
7.4211
0.3249
19
1.21
11.00 ug/L
13.31 ug/L
6 -
Cyanide
Date
Data
1
4/2/2014
<
2
6/4/2014
<
3
9/10/2014
<
4
12/2/2014
<
5
3/4/2015
<
6
6/3/2015
<
7
9/2/2015
<
8
12/9/2015
<
9
3/9/2016
<
10
6/8/2016
<
11
9/7/2016
<
12
12/14/2016
<
13
3/8/2017
<
14
6/14/2017
<
15
9/13/2017
<
16
12/6/2017
<
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Cyanide
BDL=1/2DL
Results
i 5
Std Dev.
i 5
Mean
i 5
C.V.
i 5
n
i 5
i 5
Mult Factor =
i 5
Max. Value
i 5
Max. Pred Cw
i 5
i 5
i 5
i 5
i 5
i 5
i 5
i 5
Use "PASTE SPECIAL Par14
Values" then "COPY"
. Maximum data
points = 58
Date
1 4/2/2014 <
2 6/4/2014 <
3 9/10/2014 <
4 12/2/2014 <
5 3/4/2015 <
6 6/3/2015 <
7 9/2/2015 <
8 12/9/2015 <
9 3/9/2016 <
10 6/8/2016
11 9/7/2016
12 12/14/2016
13 3/8/2017 <
14 6/14/2017 <
15 9/13/2017
16 12/6/2017 <
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
5.00
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

Lead
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
6/3/2014
5 2.5
MultFactor=
5 2.5
Max. Value
5 2.5
Max. Fred Cw
5 2.5
C.V.
6 6
12/3/2014
20 20
3.4
12 12
5
5 2.5
3.3
5 2.5
n
10 10
6/3/2015
5 2.5
1.4
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par15 Use "PASTE SPECIAL Par16 Use "PASTE SPECIAL
Values"then"COPY" Mercury Values" then "COPY" Molybdenum Values" then "COPY"
. Maximum data . Maximum data . Maximum data
points = 58 points = 58 points = 58
4.8750
1.0253
16
1.80
20.000 ug/L
36.000 ug/L
7-
4.4063
0.7855
16
1.62
11.9 ng/L
19.3 ng/L
Date
Data
BDL=1/2DL
Results
1
4/2/2014
1.1
1.1
Std Dev.
2
6/3/2014
5.5
5.5
Mean
3
9/10/2014
5.2
5.2
C.V.
4
12/3/2014
3.4
3.4
n
5
3/4/2015
3.3
3.3
n
6
6/3/2015
1.4
1.4
MultFactor=
7
9/2/2015
11.9
11.9
Max. Value
8
12/9/2015
2.3
2.3
Max. Fred Cw
9
3/9/2016
3.5
3.5
12/9/2015
10
6/8/2016
< 1
0.5
9
11
9/7/2016
9.9
9.9
12
12/13/2016
4.1
4.1
5
13
3/8/2017
< 1
0.5
10
14
6/14/2017
3.4
3.4
<
15
9/13/2017
10.1
10.1
3/8/2017
16
12/6/2017
4.4
4.4
14
17
<
10
5
18
9/13/2017
<
10
5
19
16
12/6/2017
<
10
20
17
21
18
22
19
23
24
25
21
26
22
27
23
28
24
29
30
31
26
32
27
33
28
34
29
35
36
37
31
38
32
7-
4.4063
0.7855
16
1.62
11.9 ng/L
19.3 ng/L
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
6
6/3/2015
<
10
5
MultFactor=
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
10
6/8/2016
<
10
5
11
9/7/2016
<
10
5
12
12/14/2016
<
10
5
13
3/8/2017
<
10
5
14
6/14/2017
<
10
5
15
9/13/2017
<
10
5
16
12/6/2017
<
10
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

Par17 & Par18
Nickel
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par19
Values" then "COPY"
. Maximum data
points = 58
5.3125
0.2353
16
1.17
10.0 pg/L
11.7 pg/L
Selenium
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
7
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
0.5
10
6/8/2016
<
10
5
13
11
9/7/2016
<
10
5
12/14/2016
12
12/14/2016
<
10
5
<
13
3/8/2017
<
10
5
1
14
6/14/2017
<
10
5
0.5
15
9/13/2017
<
10
10
19
16
12/6/2017
<
10
5
17
21
18
22
19
23
20
25
21
26
22
27
23
28
24
29
25
31
26
32
27
33
28
34
29
35
30
37
31
38
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par19
Values" then "COPY"
. Maximum data
points = 58
5.3125
0.2353
16
1.17
10.0 pg/L
11.7 pg/L
Selenium
8 -
Use "PASTE SPECIAL Par20
Values" then "COPY"
. Maximum data
points = 58
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Silver
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
7
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
0.5
10
6/8/2016
<
10
5
13
11
9/7/2016
<
10
5
12/14/2016
12
12/14/2016
<
10
5
<
13
3/8/2017
<
10
5
1
14
6/14/2017
<
10
5
0.5
15
9/13/2017
<
10
5
19
16
12/6/2017
<
10
5
17
21
18
22
19
23
20
25
21
26
22
27
23
28
24
29
25
31
26
32
27
33
28
34
29
35
30
37
31
38
32
33
34
35
36
37
38
8 -
Use "PASTE SPECIAL Par20
Values" then "COPY"
. Maximum data
points = 58
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Silver
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
1
3/31/2014
<
10
5
2
4/2/2014
<
1
0.5
3
6/4/2014
<
1
0.5
4
6/10/2014
<
1
0.5
5
9/10/2014
<
1
0.5
6
12/2/2014
<
1
0.5
7
3/4/2015
<
1
0.5
8
6/3/2015
<
1
0.5
9
9/2/2015
<
1
0.5
10
12/9/2015
<
1
0.5
11
3/9/2016
<
1
0.5
12
6/8/2016
<
1
0.5
13
9/7/2016
<
1
0.5
14
12/14/2016
<
1
0.5
15
3/8/2017
<
1
0.5
16
6/14/2017
<
1
0.5
17
6/20/2017
<
1
0.5
18
9/13/2017
<
1
0.5
19
12/6/2017
<
1
0.5
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par21 Use "PASTE SPECIAL
Values" then "COPY" Zinc Values" then "COPY"
. Maximum data . Maximum data
points = 58 points = 58 Par22
Results
Date Data
Std Dev.
1.0324
Mean
0.7368
C.V.
1.4011
n
19
MultFactor=
1.85
Max. Value
5.000 ug/L
Max. Fred Cw
9.250 ug/L
Use "PASTE SPECIAL Par23
Date Data
BDL=1/2DL
Results
1
4/2/2014
51
51
Std Dev.
17.0000
1
2
6/4/2014
59
59
Mean
55.7500
2
3
9/10/2014
72
72
C.V.
0.3049
3
4
12/2/2014
55
55
n
16
4
5
3/4/2015
81
81
51.600000 pg/L
5
6
6/3/2015
37
37
MultFactor=
1.23
6
7
9/2/2015
71
71
Max. Value
81.0 ug/L
7
8
12/9/2015
49
49
Max. Fred Cw
99.6 ug/L
8
9
3/9/2016
57
57
9
10
6/8/2016
23
23
10
11
9/7/2016
63
63
11
12
12/14/2016
71
71
12
13
3/8/2017
26
26
13
14
6/14/2017
52
52
14
15
9/13/2017
48
48
15
16
12/6/2017
77
77
16
17
17
18
18
19
19
20
20
21
21
22
22
23
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
Use "PASTE SPECIAL Par23
Date Da
1 9/9/2014
2 12/8/2015
3 3/15/2016
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
9- 6/27/2018
Bromoform
Values then COPY
. Maximum data
points = 58
Date Data
BDL=1/2DL
Results
9/9/2014
51.6 51.6
Std Dev.
26.4426
12/8/2015
5.8 5.8
Mean
21.0667
3/15/2016
5.8 5.8
C.V. (default)
0.6000
n
3
MultFactor=
3.00
Max. Value
51.600000 pg/L
Max. Fred Cw
154.800000 pg/L
Date Da
1 9/9/2014
2 12/8/2015
3 3/15/2016
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
9- 6/27/2018

MultFactor= 3.00
Max. Value 15.200000 ug/L
Max. Fred Cw 45.600000 Ng/L
REASONABLE POTENTIAL ANALYSIS
10-
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018
Use"PASTE SPECIAL
Dichlorobromomethane
Values" then "COPY"
. Maximum data
points = 58
to BDL=1/2DL
Results
15.2 15.2
Std Dev.
5.8312
15.2 15.2
Mean
11.8333
5.1 5.1
C.V. (default)
0.6000
n
3
MultFactor= 3.00
Max. Value 15.200000 ug/L
Max. Fred Cw 45.600000 Ng/L
REASONABLE POTENTIAL ANALYSIS
10-
RPA_Mayodan_NC0021873_Q 3 mgd_More metals, data
6/27/2018

Town of Mayodan WWTP
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM
Qw (MGD) =
3.0000
1Q10S (cfs) =
61.34
7Q10S (cfs) =
75.00
7Q10W (cfs) =
131.00
30Q2 (cfs) =
150.00
Avg. Stream Flow, QA (cfs) =
362.00
Receiving Stream: Mayo River HUC 0301010304
DATA POINTS = 58
WWTP/WTP Class: IV
IWC% @ 1Q10S =
7.0465222
IWC% @ 7Q10S =
5.838041431
IWC% @ 7Q10W =
3.42793955
1WC% @ 30Q2 =
3.006789525
IW%C @ QA =
1.268239465
Stream Class:
C
Outfall 001
Qw=3 MGD
COMBINED HARDNESS (m¢/L)
Acute = 38.26 mg/L
Chronic = 37.92 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIAJ
U)
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
a
Applied
Chronic Acute
n # Det. Max Pred Cw Allowable Cw
Standard
Acute (FW): 4,825.1
No RP, Predicted Max < 50% of Allowable Cw - No
Arsenic
C
150 FW(7Q10s) 340
ug/L
Monitoring required
16 0
2.5
Chronic (FW): 2,569.4
All values less than 5 ug/L
Max MDL =-5
Arsenic
C
10 HH/WS(Qavg)
ug/L
NO DETECTS
Chronic (HH): 788.5
_ --------------------------
____________Arsenic
All values less than 5 ug/L
Max MDL = 5
Acute: 66.665
No RP, Predicted Max < 50% of Allowable Cw - No
Cadmium
NC
0.8083 FW(7Q10s) 4.6975
ug/L
16 0
0.500
Monitoring required
- - -----------------------------
Chronic: 13.846
No detects, all less than 1 ug/L
NO DETECTS
=
Max MDL 1
Acute: 227.1
Chromium VI
NC
11 FW(7Q10s) 16
pg/L
0 0
N/A
Chronic: -----188.4--
---------------------------
Chromium, Total
NC
pg/L
20 0
2.5
Max reported value = 2.5
All values less than 5 ug/L & < Cr VI
NO DETECTS
Max MDL = 5
Acute: 221.94
No RP, Predicted Max < 50% of Allowable Cw - No
Copper
NC
11.2505 FW(7Q10s) 15.6388
ug/L
19 19
13.31
Monitoring required
---------------------------------------------
Chronic: 192.71
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 312.2
No RP, Predicted Max < 50% of Allowable Cw - No
Cyanide
NC
5 FW(7Q10s) 22
10
ug/L
16 0
5.0
Monitoring required
---------------------------------------------
Chronic: 85.6
All values less than 5 ug/L
NO DETECTS
Max MDL = 10
Acute: 1,726.689
No RP, Predicted Max < 50% of Allowable Cw - No
Lead
NC
4.6938 FW(7Q10s) 121.6715
ug/L
16 4
36.000
Monitoring required
Chronic: 80.400
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Mercury
NC
12 FW(7Q10s)
0.5
ng/L
16 14
19.3
Chronic: 205.5
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Molybdenum
NC
2000 HH(7Q10s)ug/L
16 0
5.0
INo
Chronic: 34,258.1
RP, Predicted Max < 50% of Allowable Cw - No
RPA _Mayodan_NCO021873_Q 3 mgd_More metals, rpa
Page 11 of 13 6/27/2018

Town of Mayodan WWTP - Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 3 MGD
RPA _Mayodan_NCO021873_Q 3 mgd_More metals, rpa
Page 12 of 13 6/27/2018
NO DETECTS
Max MDL— 10
Monitoring required
Acute (FW): 6,819.2
No RP, Predicted Max < 50% of Allowable Cw - No
Nickel
NC
52.9640 FW(7Q10s) 480.5146
µg/L
Monitoring required
16 1
11.7
Chronic (FW): 907.2
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable
Monitoring required
Nickel
NC
25.0000 WS(7Q10s)
µg/L
_Cw
Chronic (WS): 428.2
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 794.7
No RP, Predicted Max < 50% of Allowable Cw - No
Selenium
NC
5 FW(7Q10s) 56
ug/L
16 0
5.0
Monitoring required
-----------------------------
Chronic: 85.6
All values less than 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 8.747
Silver
NC
0.06 FW(7Q10s) 0.6164
ug/L
19 0
9.250
Chronic: 1.028
All values < 1 ug/L with one < 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 2,558.6
No RP, Predicted Max < 50% of Allowable Cw - No
Zinc
NC
180.3842 FW(7Q10s) 180.2955
ug/L
16 16
99.6
Monitoring required
Chronic: 3,089.8
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Bromoform
C
120 HH(Qavg)
µg/L
3 3
154.80000
Note: n:5 9
C.V. (default)
Chronic: 9461.93548
No RP, Predicted Max < 50% of Allowable Cw - No
Limited data set
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Dichlorobromomethane
C
27 HH(Qavg)
µg/L
3 3
45.60000
Note: n < 9
C.V. (default)
Chronic: 2128.93548
No RP, Predicted Max < 50% of Allowable Cw - No
Limited data set
No value > Allowable Cw
Monitoring required
RPA _Mayodan_NCO021873_Q 3 mgd_More metals, rpa
Page 12 of 13 6/27/2018

Date: 6/27/2018
Enter data onto "Table 1" under the Input Sheet and enter
"Effluent Hardness" under the Data Sheet.
In accordance with 40 CFR 122.45 (c), permits are, have and
must be written as total metals.
This calculator has been inserted into the RPA to calculate Total
Metal allowable allocations once Table 1 has been completed
(Input Sheet) and Effluent hardness has been entered (Data
Sheet).
1) Following the spreadsheet from left to right. First
the allowable allocations for the dissolved metals will
appear for all the metals listed once Table 1 is complete and
effluent hardness entered. Use a default value of 25 mg/L if
no hardness data is available. Second, the
Dissolved Metal allocations are divided by the Translators to
determine the Total Metals that can be allocated to the
Permittee. These Total Metals values are automatically
inserted into Table 2 and are the allowable Total Metal
allocations determined for the Permittee prior to allowing
for dilution. See Input sheet Table 2. The final acute and
chronic values shown under the RPA sheet are the Total
Metal values listed in Table 2 divided by the acute and
chronic IWC, respectively.
2) The Translators used in the freshwater RPA are the Partition
Coefficients published by US EPA in 1984. They are TSS
dependent equations and can be found listed with the WQS
hardness dependent equations under the sheet labeled
Equations. A fixed TSS value of 30 mg/L is used to calculate
the Translator values.
3) Pretreatment Facilities— PERCS will need a copy of the
Dissolved to Total Metal Calculator spreadsheet and the
RPA sheet along with the Final Permit. Pretreatment
Facilities are required to renew their Headwords Analysis
after renewal of their permits. Since all their metal
allocations are likely to change PERCS needs to see any new
metal permit limits and the allowable allocations for the
dissolved metals to assess Maximum Allowable Headworks
Loading (MAHL) numbers for each metal based on the
Combined Hardness values used in the permit writers RPA
calculations.
4) For Cadmium, Lead, Nickel, Chromium and Beryllium, if all
the effluent sampling data for the last three to five years
shows the pollutant at concentrations less than the Practical
Quantitative Level (PQL), it is not likely a limit or monitoring
will be put in the permit. However, if the estimated NPDES
permit limit is less than the Practical Quantitative Limit
(particularly, Cadmium and Lead) and the pollutant is
believed to be present, to assess compliance with the new
standards and for future permit limit development,
monitoring for the pollutant will be required. If the facility is
monitoring for the pollutant in its Pretreatment LTMP, no
monitoring is needed in the permit.
5) For monitoring and compliance purposes if Total Chromium
'Y: Town of Mayodan WWTP Outfall 001
PERMIT: NCO021873 Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
Recelving Recewl" 9
Stream Stream
su mer 7010
Hec. Jtream
1010
NHUtJ
Flow Limn
Total Suspende0
Solids
-Fixed Value-
ComDinetl
Hardness
chronic
ComDinetl
Hardness
Acute
Instream
Wastexater
ConranVatlon
Instream Emu
Wastewater Upstream Hardness
Hartlness
ConcenVaton Averege
Average
7010(CFS) (MGD)
MGD
MGD
(mg/L)
(mg/L)
(mg/L)
(Chronic)
(Acute)' (mgt) (mglL)
75.0000 1 48.3871
39.5742
3.0000
10
37.921
36.265
5.8380
7.0465 36.2580645 64.73684
Upstream Hard Avg (mg/L) = 36.25806
EFF Hard Avg (mg/L) = 64.73684
Dissolved Metals CriteriaUS
EPA
III Metal Criteria
Tela) Metal=
COMMENTS (Identify parameters to PERCS Branch to maintain in facility's LTMP/STMP):
after applying hartlness
PARAMETER uaron
Translators -using
Default Partition
Dissolved Mesa+Tansia.r
Chronic Acute
Coefficients
Chronic
I Acute
0.202 165.61
1.000 11.00
N/A
0.348 11.25
0.184 4.69
0.432 52.96
25
1.000 0.06
0.2881 180.38
=dissolved metal standard.5ee 15A NCAC 026.0211 for more information.
= hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
= based upon measurement of total recaveable metal. See 15A NCAC 02B.0211 far mare informadon.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Toml Recoverable metal standard.
The Human Health standard for Arsenic is 30 pg/L which is Total Recoverable metal standard.
ACA H 38.26483
ACCH 37.92067

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
WWTP/WTP Class
NPDES Permit
Outfall
Flow, Qw (MGD)
Receiving Stream
HUC Number
Stream Class
]Apply WS Hardness WQC
7Q1Os (cfs)
7011 Ow (cfs)
30Q2 (cfs)
QA (cfs)
1 Q1 Os (cfs)
Effluent Hardness_
Upstream Hardness_
Combined Hardness Chronic_
Combined Hardness Acute
Data Source(s)
❑CHECK TO APPLY MODEL
Town of Mayodan WWTP
IV
NCO021873
001
4.500
Mayo River
0301010304
C
75.00
131.00
150.00
362.00
61.34
64.74 mg/L (Avg)
-------------------
36.26 mg/L (Avg)
-------------------
38.68 mg/L
-------------------
39.17 mg/L
REQUIRED DATA ENTRY
Par01
Par02
Par03
Par04
Par05
Par06111111
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
0.8205
FW
4.7939
ug/L
Chlorides
Aquatic Life
NC
230
FW
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
168.3242
FW
1307.2705
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
11.4430
FW
15.9855
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
4.7990
FW
124.8735
ug/L
Mercury
Aquatic Life
NC
12
FW
0.5 ng/L
Molybdenum
Human Health
NC
2000
HH
ug/L
Nickel
Aquatic Life
NC
53.8613
FW
490.0688
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
0.6415
ug/L
Zinc
Aquatic Life
NC
183.4450
FW
183.8859
ug/L
Bromoform
Human Health
C
120
HH
pg/L
Dichlorobromomethane
Human Health
C
27
HH
pg/L
RPA_Mayodan_NCO021873_Q 4.5 mgd_More metals, input
6/27/2018

RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, input
6/27/2018

REASONABLE POTENTIAL ANALYSIS
1
Effluent Hardness
Use "PASTE SPECIAL
Values" then "COPY"
H2
Upstream Hardness
Use "PASTE SPECIAL
Values" then "COPY"
Par01 & Par02
Arsenic
. Maximum data
. Maximum data
points = 58
points = 58
Date
Data
BDL=1/2DL
Results
Date
Data
BDL=1/2DL
Results
Date Data
BDL=1/2DL
1 9/9/2014
69
69
Std Dev.
20.6917
1
6/21/2016
40
40
Std Dev.
15.3601
1
4/2/2014 <
5
2.5
2 12/8/2015
44
44
Mean
64.7368
2
7/5/2016
75
75
Mean
36.2581
2
6/4/2014 <
5
2.5
3 3/15/2016
57
57
C.V.
0.3196
3
7/19/2016
52
52
C.V.
0.4236
3
9/10/2014 <
5
2.5
4 6/21/2016
68
68
n
38
4
8/2/2016
44
44
n
31
4
12/2/2014 <
5
2.5
5 7/5/2016
135
135
10th Per value
44.00 mg/L
5
8/16/2016
78
78
10th Per value
20.00 mg/L
5
3/4/2015 <
5
2.5
6 7/19/2016
84
84
Average Value
64.74 mg/L
6
9/6/2016
41
41
Average Value
36.26 mg/L
6
6/3/2015 <
5
2.5
7 8/2/2016
85
85
Max. Value
135.00 mg/L
7
9/20/2016
60
60
Max. Value
78.00 mg/L
7
9/2/2015 <
5
2.5
8 8/16/2016
78
78
8
10/4/2016
53
53
8
12/9/2015 <
5
2.5
9 9/6/2016
90
90
9
10/18/2016
32
32
9
3/9/2016 <
5
2.5
10 9/20/2016
104
104
10
12/13/2016
32
32
10
6/8/2016 <
5
2.5
11 10/4/2016
85
85
11
12/20/2016
36
36
11
9/7/2016 <
5
2.5
12 10/18/2016
68
68
12
1/10/2017
33
33
12
12/14/2016 <
5
2.5
13 12/13/2016
68
68
13
1/17/2017
36
36
13
3/8/2017 <
5
2.5
14 12/20/2016
92
92
14
1/31/2017
20
20
14
6/14/2017 <
5
2.5
15 1/10/2017
82
82
15
2/28/2017
20
20
15
9/13/2017 <
5
2.5
16 1/17/2017
76
76
16
3/7/2017
36
36
16
12/6/2017 <
5
2.5
17 1/31/2017
65
65
17
3/21/2017
24
24
17
18 2/28/2017
56
56
18
4/4/2017
20
20
18
19 3/7/2017
44
44
19
4/19/2017
28
28
19
20 3/21/2017
44
44
20
5/2/2017
24
24
20
21 4/5/2017
48
48
21
5/16/2017
56
56
21
22 4/19/2017
60
60
22
9/5/2017
20
20
22
23 5/2/2017
44
44
23
9/19/2017
20
20
23
24 5/16/2017
84
84
24
10/4/2017
28
28
24
25 6/6/2017
48
48
25
11/7/2017
24
24
25
26 6/20/2017
29
29
26
11/21/2017
28
28
26
27 8/1/2017
63
63
27
12/6/2017
28
28
27
28 8/16/2017
63
63
28
1/2/2018
24
24
28
29 9/5/2017
56
56
29
1/16/2018
36
36
29
30 9/19/2017
48
48
30
2/7/2018
36
36
30
31 10/4/2017
64
64
31
2/20/2018
40
40
31
32 11/7/2017
40
40
32
32
33 11/21/2017
52
52
33
33
34 12/6/2017
52
52
34
34
35 1/2/2018
60
60
35
35
36 1/16/2018
55
55
36
36
37 2/7/2018
60
60
37
37
38 2/20/2018
40
40
38
38
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
3- 6/27/2018

Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018
Use"PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58
Results
Std Dev.
0.0000
Mean
2.5000
C.V.
0.0000
n
16
Mult Factor = 1.00
Max. Value 2.5 ug/L
Max. Pred Cw 2.5 ug/L
REASONABLE POTENTIAL ANALYSIS
4-
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

Cadmium
Date Data BDL=1/2DL Results
1 4/2/2014 < 1 0.5 Std Dev.
2 6/4/2014 < 1 0.5 Mean
3 9/10/2014 < 1 0.5 C.V.
4 12/2/2014 < 1 0.5 n
5 3/4/2015 < 1 0.5
6 6/3/2015 < 1 0.5 Mult Factor =
7 9/2/2015 < 1 0.5 Max. Value
8 12/9/2015 < 1 0.5 Max. Pred Cw
9 3/9/2016 < 1 0.5
10 6/8/2016 < 1 0.5
11 9/7/2016 < 1 0.5
12 12/14/2016 < 1 0.5
13 3/8/2017 < 1 0.5
14 6/14/2017 < 1 0.5
15 9/13/2017 < 1 0.5
16 12/6/2017 < 1 0.5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Pdr09
Values" then "COPY"
. Maximum data
points = 58
0.5000
0.0000
16
1.00
0.500 ug/L
0.500 ug/L
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Chromium VI
Date Data BDL=1/2DL Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Pred Cw
5 -
Use "PASTE SPECIAL
Values" then "COPY"
. Maximum data
points = 58 r
NO DATA
NO DATA
0
N/A
N/A pg/L
N/A pg/L
Chromium, Tot;
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
1
3/31/2014
<
5
2.5
2
4/2/2014
<
5
2.5
3
6/4/2014
<
5
2.5
4
6/10/2014
<
5
2.5
5
9/10/2014
<
5
2.5
6
12/2/2014
<
5
2.5
7
3/4/2015
<
5
2.5
8
6/3/2015
<
5
2.5
9
9/2/2015
<
5
2.5
10
12/9/2015
<
5
2.5
11
3/9/2016
<
5
2.5
12
3/15/2016
<
5
2.5
13
6/8/2016
<
5
2.5
14
9/7/2016
<
5
2.5
15
12/14/2016
<
5
2.5
16
3/8/2017
<
5
2.5
17
6/14/2017
<
5
2.5
18
6/20/2017
<
5
2.5
19
9/13/2017
<
5
2.5
20
12/6/2017
<
5
2.5
21
22
23
24
250
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

31
Results
Std Dev.
Mean
C.V.
n
Mult Factor =
Max. Value
Max. Fred Cw
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Pal Use "PASTE SPECIAL Par12
Values" then "COPY" Copper Values" then "COPY"
. Maximum data . Maximum data
points = 58 points = 58
2.5000
0.0000
20
1.00
2.5 pg/L
2.5 pg/L
7.4211
0.3249
19
1.21
11.00 ug/L
13.31 ug/L
6 -
Date Data
Data
BDL=1/2DL
Results
1
3/31/2014
7
7
Std Dev.
2
4/2/2014
6
6
Mean
3
6/4/2014
8
8
C.V.
4
6/10/2014
10
10
n
5
9/10/2014
11
11
<
6
12/2/2014
9
9
MultFactor=
7
3/4/2015
10
10
Max. Value
8
6/3/2015
3
3
Max. Fred Cw
9
9/2/2015
5
5
12/6/2017
10
12/9/2015
6
6
18
11
3/9/2016
5
5
12
6/8/2016
5
5
13
9/7/2016
9
9
23
14
12/14/2016
9
9
15
3/8/2017
6
6
16
6/14/2017
5
5
28
17
6/20/2017
6
6
18
9/13/2017
10
10
19
12/6/2017
11
11
33
20
34
21
36
22
37
38
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
7.4211
0.3249
19
1.21
11.00 ug/L
13.31 ug/L
6 -
Cyanide
Date
Data
1
4/2/2014
<
2
6/4/2014
<
3
9/10/2014
<
4
12/2/2014
<
5
3/4/2015
<
6
6/3/2015
<
7
9/2/2015
<
8
12/9/2015
<
9
3/9/2016
<
10
6/8/2016
<
11
9/7/2016
<
12
12/14/2016
<
13
3/8/2017
<
14
6/14/2017
<
15
9/13/2017
<
16
12/6/2017
<
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
Cyanide
BDL=1/2DL
Results
i 5
Std Dev.
i 5
Mean
i 5
C.V.
i 5
n
i 5
i 5
MultFactor=
i 5
Max. Value
i 5
Max. Fred Cw
i 5
i 5
i 5
i 5
i 5
i 5
i 5
i 5
Use "PASTE SPECIAL Par14
Values" then "COPY"
. Maximum data
points = 58
Date
1 4/2/2014 <
2 6/4/2014 <
3 9/10/2014 <
4 12/2/2014 <
5 3/4/2015 <
6 6/3/2015 <
7 9/2/2015 <
8 12/9/2015 <
9 3/9/2016 <
10 6/8/2016
11 9/7/2016
12 12/14/2016
13 3/8/2017 <
14 6/14/2017 <
15 9/13/2017
16 12/6/2017 <
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
5.00
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

Lead
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
6/3/2014
5 2.5
MultFactor=
5 2.5
Max. Value
5 2.5
Max. Fred Cw
5 2.5
C.V.
6 6
12/3/2014
20 20
3.4
12 12
5
5 2.5
3.3
5 2.5
n
10 10
6/3/2015
5 2.5
1.4
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par15 Use "PASTE SPECIAL Par16 Use "PASTE SPECIAL
Values"then"COPY" Mercury Values" then "COPY" Molybdenum Values" then "COPY"
. Maximum data . Maximum data . Maximum data
points = 58 points = 58 points = 58
4.8750
1.0253
16
1.80
20.000 ug/L
36.000 ug/L
7-
4.4063
0.7855
16
1.62
11.9 ng/L
19.3 ng/L
Date
Data
BDL=1/2DL
Results
1
4/2/2014
1.1
1.1
Std Dev.
2
6/3/2014
5.5
5.5
Mean
3
9/10/2014
5.2
5.2
C.V.
4
12/3/2014
3.4
3.4
n
5
3/4/2015
3.3
3.3
n
6
6/3/2015
1.4
1.4
MultFactor=
7
9/2/2015
11.9
11.9
Max. Value
8
12/9/2015
2.3
2.3
Max. Fred Cw
9
3/9/2016
3.5
3.5
12/9/2015
10
6/8/2016
< 1
0.5
9
11
9/7/2016
9.9
9.9
12
12/13/2016
4.1
4.1
5
13
3/8/2017
< 1
0.5
10
14
6/14/2017
3.4
3.4
<
15
9/13/2017
10.1
10.1
3/8/2017
16
12/6/2017
4.4
4.4
14
17
<
10
5
18
9/13/2017
<
10
5
19
16
12/6/2017
<
10
20
17
21
18
22
19
23
24
25
21
26
22
27
23
28
24
29
30
31
26
32
27
33
28
34
29
35
36
37
31
38
32
7-
4.4063
0.7855
16
1.62
11.9 ng/L
19.3 ng/L
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
6
6/3/2015
<
10
5
MultFactor=
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
10
6/8/2016
<
10
5
11
9/7/2016
<
10
5
12
12/14/2016
<
10
5
13
3/8/2017
<
10
5
14
6/14/2017
<
10
5
15
9/13/2017
<
10
5
16
12/6/2017
<
10
5
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

Par17 & Par18
Nickel
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par19
Values" then "COPY"
. Maximum data
points = 58
5.3125
0.2353
16
1.17
10.0 pg/L
11.7 pg/L
Selenium
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
7
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
0.5
10
6/8/2016
<
10
5
13
11
9/7/2016
<
10
5
12/14/2016
12
12/14/2016
<
10
5
<
13
3/8/2017
<
10
5
1
14
6/14/2017
<
10
5
0.5
15
9/13/2017
<
10
10
19
16
12/6/2017
<
10
5
17
21
18
22
19
23
20
25
21
26
22
27
23
28
24
29
25
31
26
32
27
33
28
34
29
35
30
37
31
38
32
33
34
35
36
37
38
REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par19
Values" then "COPY"
. Maximum data
points = 58
5.3125
0.2353
16
1.17
10.0 pg/L
11.7 pg/L
Selenium
8 -
Use "PASTE SPECIAL Par20
Values" then "COPY"
. Maximum data
points = 58
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Silver
Date
Data
BDL=1/2DL
Results
1
4/2/2014
<
10
5
Std Dev.
2
6/4/2014
<
10
5
Mean
3
9/10/2014
<
10
5
C.V.
4
12/2/2014
<
10
5
n
5
3/4/2015
<
10
5
7
6
6/3/2015
<
10
5
Mult Factor =
7
9/2/2015
<
10
5
Max. Value
8
12/9/2015
<
10
5
Max. Fred Cw
9
3/9/2016
<
10
5
0.5
10
6/8/2016
<
10
5
13
11
9/7/2016
<
10
5
12/14/2016
12
12/14/2016
<
10
5
<
13
3/8/2017
<
10
5
1
14
6/14/2017
<
10
5
0.5
15
9/13/2017
<
10
5
19
16
12/6/2017
<
10
5
17
21
18
22
19
23
20
25
21
26
22
27
23
28
24
29
25
31
26
32
27
33
28
34
29
35
30
37
31
38
32
33
34
35
36
37
38
8 -
Use "PASTE SPECIAL Par20
Values" then "COPY"
. Maximum data
points = 58
5.0000
0.0000
16
1.00
5.0 ug/L
5.0 ug/L
Silver
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018
Date
Data
BDL=1/2DL
1
3/31/2014
<
10
5
2
4/2/2014
<
1
0.5
3
6/4/2014
<
1
0.5
4
6/10/2014
<
1
0.5
5
9/10/2014
<
1
0.5
6
12/2/2014
<
1
0.5
7
3/4/2015
<
1
0.5
8
6/3/2015
<
1
0.5
9
9/2/2015
<
1
0.5
10
12/9/2015
<
1
0.5
11
3/9/2016
<
1
0.5
12
6/8/2016
<
1
0.5
13
9/7/2016
<
1
0.5
14
12/14/2016
<
1
0.5
15
3/8/2017
<
1
0.5
16
6/14/2017
<
1
0.5
17
6/20/2017
<
1
0.5
18
9/13/2017
<
1
0.5
19
12/6/2017
<
1
0.5
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

REASONABLE POTENTIAL ANALYSIS
Use "PASTE SPECIAL Par21 Use "PASTE SPECIAL
Values" then "COPY" Zinc Values" then "COPY"
. Maximum data . Maximum data
points = 58 points = 58 Par22
Results
Date Data
Std Dev.
1.0324
Mean
0.7368
C.V.
1.4011
n
19
MultFactor=
1.85
Max. Value
5.000 ug/L
Max. Fred Cw
9.250 ug/L
Use "PASTE SPECIAL Par23
Date Data
BDL=1/2DL
Results
1
4/2/2014
51
51
Std Dev.
17.0000
1
2
6/4/2014
59
59
Mean
55.7500
2
3
9/10/2014
72
72
C.V.
0.3049
3
4
12/2/2014
55
55
n
16
4
5
3/4/2015
81
81
51.600000 pg/L
5
6
6/3/2015
37
37
MultFactor=
1.23
6
7
9/2/2015
71
71
Max. Value
81.0 ug/L
7
8
12/9/2015
49
49
Max. Fred Cw
99.6 ug/L
8
9
3/9/2016
57
57
9
10
6/8/2016
23
23
10
11
9/7/2016
63
63
11
12
12/14/2016
71
71
12
13
3/8/2017
26
26
13
14
6/14/2017
52
52
14
15
9/13/2017
48
48
15
16
12/6/2017
77
77
16
17
17
18
18
19
19
20
20
21
21
22
22
23
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
Use "PASTE SPECIAL Par23
Date Da
1 9/9/2014
2 12/8/2015
3 3/15/2016
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
9- 6/27/2018
Bromoform
Values then COPY
. Maximum data
points = 58
Date Data
BDL=1/2DL
Results
9/9/2014
51.6 51.6
Std Dev.
26.4426
12/8/2015
5.8 5.8
Mean
21.0667
3/15/2016
5.8 5.8
C.V. (default)
0.6000
n
3
MultFactor=
3.00
Max. Value
51.600000 pg/L
Max. Fred Cw
154.800000 pg/L
Date Da
1 9/9/2014
2 12/8/2015
3 3/15/2016
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
9- 6/27/2018

MultFactor= 3.00
Max. Value 15.200000 ug/L
Max. Fred Cw 45.600000 Ng/L
REASONABLE POTENTIAL ANALYSIS
10-
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018
Use"PASTE SPECIAL
Dichlorobromomethane
Values" then "COPY"
. Maximum data
points = 58
to BDL=1/2DL
Results
15.2 15.2
Std Dev.
5.8312
15.2 15.2
Mean
11.8333
5.1 5.1
C.V. (default)
0.6000
n
3
MultFactor= 3.00
Max. Value 15.200000 ug/L
Max. Fred Cw 45.600000 Ng/L
REASONABLE POTENTIAL ANALYSIS
10-
RPA_Mayodan_NC0021873_Q 4.5 mgd_More metals, data
6/27/2018

Town of Mayodan WWTP -
NC0021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators
MAXIMUM
Qw (MGD) =
4.5000
1Q10S (cfs) =
61.34
7Q10S (cfs) =
75.00
7Q10W (cfs) =
131.00
30Q2 (cfs) =
150.00
Avg. Stream Flow, QA (cfs) =
362.00
Receiving Stream: Mayo River HUC 0301010304
DATA POINTS = 58
WWTP/WTP Class: IV
IWC% @ 1Q10S =
10.21005636
IWC% @ 7Q10S =
8.508691674
IWC% @ 7Q10W =
5.055263635
1WC% @ 30Q2 =
4.443382704
IW%C @ QA =
1.890371976
Stream Class:
C
Outfall 001
Qw = 4.5 MGD
COMBINED HARDNESS (me/L)
Acute = 39.17 mg/L
Chronic = 38.68 mg/L
PARAMETER
NC STANDARDS OR EPA CRITERIA
REASONABLE POTENTIAL RESULTS
RECOMMENDED ACTION
TYPE
J
a
Applied
Chronic Acute
n # Det. Max Pred Cw Allowable Cw
Standa
Acute (FW): 3,330.1
No RP, Predicted Max < 50% of Allowable Cw - No
Arsenic
C
150 FW(7Q10s) 340
ug/L
Monitoring required
16 0
2.5
Chronic 1,762.9
All values less than 5 ug/L
Max MDL = 5
Arsenic
C
10 HH/WS(Qavg)
ug/L
NO DETECTS
_ _ _ _
Chronic (HH): 529.0
_--------------------------
____________________Arsenic
All values less than 5 ug/L
Max MDL = 5
Acute: 46.953
No RP, Predicted Max < 50% of Allowable Cw - No
Cadmium
NC
0.8205 FW(7Q10s) 4.7939
ug/L
16 0
0.500
Monitoring required
- - -----------------------------
Chronic: 9.643
None detects, all less than 1 ug/L
NO DETECTS
Max MDL = 1
Acute: 156.7
Chromium VI
NC
11 FW(7Q10s) 16
Itg/L
0 0
N/A
Chronic: -----129.3--
---------------------------
Chromium, Total
NC
VgIL
20 0
2.5
Max reported value = 2.5
All values less than 5 ug/L & < Cr IV
NO DETECTS
Max MDL = 5
Acute: 156.57
No RP, Predicted Max < 50% of Allowable Cw - No
Copper
NC
11.4430 FW(7Q10s) 15.9855
ug/L
19 19
13.31
Monitoring required
---------------------------------------------
Chronic: 134.49
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 215.5
No RP, Predicted Max < 50% of Allowable Cw - No
Cyanide
NC
5 FW(7Q10s) 22
10
ug/L
16 0
5.0
Monitoring required
---------------------------------------------
Chronic: 58.8
All values less than 5 ug/L
NO DETECTS
Max MDL = 10
Acute: 1,223.044
No RP, Predicted Max < 50% of Allowable Cw - No
Lead
NC
4.7990 FW(7Q10s) 124.8735
ug/L
16 4
36.000Monitoring
required
Chronic: 56.401
No RP , Predicted Max >_ 50% of Allowable Cw
No value > Allowable Cw
apply Quarterly Monitoring
Acute: NO WQS
Mercury
NC
12 FW(7Q10s)
0.5
ng/L
16 14
19.3
Chronic: 141.0
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Molybdenum
NC
2000 HH(7Q10s)
ug/L
16 0
5.0
Chronic: 23,505.4
No RP, Predicted Max < 50% of Allowable Cw - No
NO DETECTS
Max MDL = 10
Monitoring required
RPA_ Mayodan_NC0021873_Q 4.5 mgd_More metals, rpa
Page 11 of 13 6/27/2018

Town of Mayodan WWTP - Outfall 001
NCO021873 Freshwater RPA - 95% Probability/95% Confidence Using Metal Translators Qw = 4.5 MGD
RPA_ Mayodan_NC0021873_Q 4.5 mgd_More metals, rpa
Page 12 of 13 6/27/2018
Acute (FW): 4,799.9
No RP, Predicted Max < 50% of Allowable Cw - No
Nickel
NC
53.8613 FW(7Q10s) 490.0688
gg/L
Monitoring required
16 1
11.7
---------------------------------------------
Chronic (FW): 633.0
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
------------------------------
Monitoring required
Nickel
NC
25.0000 WS(7Q10s)
µg,L
Chronic (WS): 293.8
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: 548.5
No RP, Predicted Max < 50% of Allowable Cw - No
Selenium
NC
5 FW(7Q10s) 56
ug/L
16 0
5.0
Monitoring required
Chronic: 58.8
All values less than 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 6.283
Silver
NC
0.06 FW(7Q10s) 0.6415
ug/L
19 0
9.250
Chronic: 0.705
All values < 1 ug/L with one < 10 ug/L
NO DETECTS
Max MDL = 10
Acute: 1,801.0
No RP, Predicted Max < 50% of Allowable Cw - No
Zinc
NC
183.4450 FW(7Q10s) 183.8859
ug/L
16 16
99.6
Monitoring required
Chronic: 2,156.0
No RP, Predicted Max < 50% of Allowable Cw - No
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Bromoform
c
120 HH(Qavg)
gg/L
3 3
154.80000
Note: n:5 9
C.V. (default)
Chronic: 6347.95699
No RP, Predicted Max < 50% of Allowable Cw - No
Limited data set
No value > Allowable Cw
Monitoring required
Acute: NO WQS
Dichlorobromomethane c
27 HH(Qavg)
gg/L
33
45.60000
Note: n < 9
C.V. (default)
Chronic: 1428.29032
No RP, Predicted Max < 50% of Allowable Cw - No
Limited data set
INo value > Allowable Cw
Monitoring required
RPA_ Mayodan_NC0021873_Q 4.5 mgd_More metals, rpa
Page 12 of 13 6/27/2018

Date: 6/27/2018
Enter data onto "Table 1" under the Input Sheet and enter
"Effluent Hardness" under the Data Sheet.
In accordance with 40 CFR 122.45 (c), permits are, have and
must be written as total metals.
This calculator has been inserted into the RPA to calculate Total
Metal allowable allocations once Table 1 has been completed
(Input Sheet) and Effluent hardness has been entered (Data
Sheet).
1) Following the spreadsheet from left to right. First
the allowable allocations for the dissolved metals will
appear for all the metals listed once Table 1 is complete and
effluent hardness entered. Use a default value of 25 mg/L if
no hardness data is available. Second, the
Dissolved Metal allocations are divided by the Translators to
determine the Total Metals that can be allocated to the
Permittee. These Total Metals values are automatically
inserted into Table 2 and are the allowable Total Metal
allocations determined for the Permittee prior to allowing
for dilution. See Input sheet Table 2. The final acute and
chronic values shown under the RPA sheet are the Total
Metal values listed in Table 2 divided by the acute and
chronic IWC, respectively.
2) The Translators used in the freshwater RPA are the Partition
Coefficients published by US EPA in 1984. They are TSS
dependent equations and can be found listed with the WQS
hardness dependent equations under the sheet labeled
Equations. A fixed TSS value of 30 mg/L is used to calculate
the Translator values.
3) Pretreatment Facilities— PERCS will need a copy of the
Dissolved to Total Metal Calculator spreadsheet and the
RPA sheet along with the Final Permit. Pretreatment
Facilities are required to renew their Headwords Analysis
after renewal of their permits. Since all their metal
allocations are likely to change PERCS needs to see any new
metal permit limits and the allowable allocations for the
dissolved metals to assess Maximum Allowable Headworks
Loading (MAHL) numbers for each metal based on the
Combined Hardness values used in the permit writers RPA
calculations.
4) For Cadmium, Lead, Nickel, Chromium and Beryllium, if all
the effluent sampling data for the last three to five years
shows the pollutant at concentrations less than the Practical
Quantitative Level (PQL), it is not likely a limit or monitoring
will be put in the permit. However, if the estimated NPDES
permit limit is less than the Practical Quantitative Limit
(particularly, Cadmium and Lead) and the pollutant is
believed to be present, to assess compliance with the new
standards and for future permit limit development,
monitoring for the pollutant will be required. If the facility is
monitoring for the pollutant in its Pretreatment LTMP, no
monitoring is needed in the permit.
5) For monitoring and compliance purposes if Total Chromium
'Y: Town of Mayodan WWTP Outfall 001
PERMIT: NCO021873 Dissolved to Total Metal Calculator
In accordance with Federal Regulations, permit limitations must be written as Total Metals per 40 CFR 122.45(c)
Recelving Recewl" 9
Stream Stream
Hec. Jtream
NHUtJ
Total Suspende0
Solids
ComDinetl
Hardness
ComDinetl
Hardness
Instream
Wastexater
Instream EmueM
Wastewater Upstream Hardness
su mer 7010
1010
Flow Limn
-FNetl Value-
chronic
Acute
ConranVatlon
Hartlness
ConcenVatlon Averege
Average(mg4)
7010(CFS) (MGD)
MGD
MGD
(mg/L)
(mg/L)
(mg/L)
(Chronic)
(Acute) (mglL)
75.0000 1 48.3871
39.5742
4.5000
10
38.681
39.166
8.5087
10.2101 36.2580645 64.73684
Upstream Hard Avg (mg/L) = 36.25806
EFF Hard Avg (mg/L) = 64.73684
Dissolved Metals CriteriaUS
EPA
III Metal Criteria
Tela) Metal=
COMMENTS (Identify parameters to PERCS Branch to maintain in facility's LTMP/STMP):
after applying hartlness
PARAMETER uaron
Translators -using
Default Partition
Dissolved Mega+Transia.r
Chronic Acute
Coefficients
Chronic
I Acute
0.202 168.32
1.000 11.00
N/A
0.348 11.44
0.184 4.80
0.432 53.86
25
1.000 0.06
0.2881 183.44
=dissolved metal standard.5ee 15A NCAC 026.0211 for more information.
= hardness -dependent dissolved metal standard. See 15A NCAC 02B.0211 for more information.
= based upon measurement of total recaveable metal. See 15A NCAC 02B.0211 far mare informadon.
The Human Health standard for Nickel in Water Supply Streams is 25 mg/L which is Toml Recoverable metal standard.
The Human Health standard for Arsenic is 30 pg/L which is Total Recoverable metal standard.
ACA H 39.16576
ACCH 38.68124

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NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Qais Banihani
Enter Design Flow (MGD): 2.5
Enter s7Q10 (cfs): 75
Enter w7Q10 cfs : 131
Total Residual Chlorine (TRC)
Daily Maximum Limit (ug/1)
Ammonia (Summer)
Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS)
75
s7Q10 (CFS)
75
DESIGN FLOW (MGD)
2.5
DESIGN FLOW (MGD)
2.5
DESIGN FLOW (CFS)
3.875
DESIGN FLOW (CFS)
3.875
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.22
IWC (%)
4.91
IWC (%)
4.91
Allowable Conc. (ug/1)
346
Allowable Conc. (mg/1)
16.1
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
131
Monthly Average Limit:
200/100ml DESIGN FLOW (MGD)
2.5
(If DF >331; Monitor)
DESIGN FLOW (CFS)
3.875
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
20.35 Upstream Bkgd (mg/1)
0.22
IWC (%)
2.87
Allowable Conc. (mg/1)
55.2
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/I to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/1, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)

NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Qais Banihani
Enter Design Flow (MGD): 3
Enter s7Q10 (cfs): 75
Enter w7Q10 cfs : 131
Total Residual Chlorine (TRC)
Daily Maximum Limit (ug/1)
Ammonia (Summer)
Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS)
75
s7Q10 (CFS)
75
DESIGN FLOW (MGD)
3
DESIGN FLOW (MGD)
3
DESIGN FLOW (CFS)
4.65
DESIGN FLOW (CFS)
4.65
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.22
IWC (%)
5.84
IWC (%)
5.84
Allowable Conc. (ug/1)
291
Allowable Conc. (mg/1)
13.6
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
131
Monthly Average Limit:
200/100ml DESIGN FLOW (MGD)
3
(If DF >331; Monitor)
DESIGN FLOW (CFS)
4.65
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
17.13 Upstream Bkgd (mg/1)
0.22
IWC (%)
3.43
Allowable Conc. (mg/1)
46.3
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/I to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/1, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)

NH3/TRC WLA Calculations
Facility: Mayodan WWTP
PermitNo. NC0021873
Prepared By: Qais Banihani
Enter Design Flow (MGD): 4.5
Enter s7Q10 (cfs): 75
Enter w7Q10 cfs : 131
Total Residual Chlorine (TRC)
Daily Maximum Limit (ug/1)
Ammonia (Summer)
Monthly Average Limit (mg NH3-N/1)
s7Q10 (CFS)
75
s7Q10 (CFS)
75
DESIGN FLOW (MGD)
4.5
DESIGN FLOW (MGD)
4.5
DESIGN FLOW (CFS)
6.975
DESIGN FLOW (CFS)
6.975
STREAM STD (UG/L)
17.0
STREAM STD (MG/L)
1.0
Upstream Bkgd (ug/1)
0
Upstream Bkgd (mg/1)
0.22
IWC (%)
8.51
IWC (%)
8.51
Allowable Conc. (ug/1)
200
Allowable Conc. (mg/1)
9.4
Ammonia (Winter)
Monthly Average Limit (mg NH3-N/1)
Fecal Coliform
w7Q10 (CFS)
131
Monthly Average Limit:
200/100ml DESIGN FLOW (MGD)
4.5
(If DF >331; Monitor)
DESIGN FLOW (CFS)
6.975
(If DF<331; Limit)
STREAM STD (MG/L)
1.8
Dilution Factor (DF)
11.75 Upstream Bkgd (mg/1)
0.22
IWC (%)
5.06
Allowable Conc. (mg/1)
31.5
Total Residual Chlorine
1. Cap Daily Max limit at 28 ug/I to protect for acute toxicity
Ammonia (as NH3-N)
1. If Allowable Conc > 35 mg/1, Monitor Only
2. Monthly Avg limit x 3 = Weekly Avg limit (Municipals)
3. Monthly Avg limit x 5 = Daily Max limit (Non-Munis)
If the allowable ammonia concentration is > 35 mg/L, no limit shall be imposed
Fecal Coliform
1. Monthly Avg limit x 2 = 400/100 ml = Weekly Avg limit (Municipals) = Daily Max limit (Non -Muni)