NC0026611_Plan of Action_20220804

MOREHEAD CITY
iiimilowowNORTH CAROLINA
RECEIVED
AUG 0 8 2022
August 4,2022 NCDEQIDWRINPDES
NCDEQ/Division of Water Resources
Attn:NPDES Complex Permitting
1617 Mail Service Center
Raleigh,NC 27699-1617
SUBJECT: Plan of Action
NPDES NC0026611
Morehead City WWTP
Carteret County
Dear Permitting Unit:
The Town of Morehead City operates its WWTP via subject NPDES Permit effective March 1,2020.
The Permit requires the Town submit a"Plan of Action"to address limits for copper,nickel and zinc that
were added to the Town's Permit in 2020. The attached"Plan of Action"describes efforts to date along
with future proposed actions.
If you have any questions or comments,please contact me.
Sincerely,
� L
Daniel Williams
Public Utilities Director
Cc:NCDEQ/Division of Water Resources
Wilmington Regional Office
127 Cardinal Drive Ext.
Wilmington,NC 28405
McDavid Associates,Inc.
Morehead City is dedicated to the well-being and safety of our community through exceptional service with a warm coastal smile.
1100 Bridges Street I Morehead City,North Carolina 28557 I Phone[phone] I www.moreheadcitync.org

MOREHEAD CITY WASTEWATER TREATMENT PLANT ACTION PLAN FOR
ADDRESSING NPDES PERMIT LIMITS FOR COPPER,NICKEL,AND ZINC
AUGUST 2022
Morehead City's NPDES Permit NC0026611 contains limits for total copper(1.85 ug/l
monthly average),total nickel (4.15 ug/l monthly average)and total zinc (42.8 ug/1 monthly
average)effective March 1,2025. The WWTP began sampling for these three metals in
February 2018 on a quarterly basis. The sampling frequency for these three metals was
increased to monthly in February 2020. The attached spreadsheet illustrates the sampling
histories of these metals since February 2018. Compliance with the copper limit(1.85 ug/1)
has only been achieved twice out of the 53 samples illustrated on the spreadsheet. The two
occasions indicating compliance are believed to be lab reporting errors(reported results are
indicated in ug/1 but are believed to be in mg/1)and not true compliance. The zinc NPDES
limit of 42.8 ug/1 was not achieved in 4 of the 51 samples. The nickel NPDES limit of 4.15
ug/1 was not achieved in 3 of the 50 samples. It is noted the source water(Castle Hayne
aquifer)collected April 27, 2020, from the Town's 4 wells contained 13 ug/1, 185 ug/1, 30
ug/1 and 22 ug/1 copper,respectively. Zinc in the raw water amounted to 43 ug/l, 11 ug/1, 6
ug/1 and 11 ug/l,respectively. Nickel was reported as less than 2 ug/1 from each of the four
wells.
It is noted that stream samples(note that Calico Creek is tidal)often exceed the limits for
copper and zinc and are often significantly higher than the wastewater being discharged(the
discharge is diluting instream concentrations of zinc). Of 38 stream samples(19 upstream
and 19 downstream)collected between March 10,2020,and April 5,2022,only 11 samples
were reported less than 1.85 ug/1 for copper; however, it is noted another 19 samples were
reported at 2.00 ug/1,which is only slightly above the limit. The highest value reported for
copper was 5 ug/1 in April 2022. Nickel results were consistently below the NPDES Permit
limit. A total of 30 stream samples(15 upstream and 15 downstream)were collected for zinc
between March 10,2020, and April 5, 2022. Nine of the 14 upstream samples were higher
than the NPDES limit of 42.8 ug/1 with the highest sample being 198 ug/1 collected in March,
2020. Seven of the 19 downstream samples exceeded the permit limit with the single
highest sample of 120 ugh reported in June 2021
The Town began feeding alum approximately a year ago on a continuing basis in order to
improve the WWTP's removal of suspended solids in an effort to further reduce copper and
zinc levels. The most recent 12 months of sampling data reflect improved levels of
reductions in copper and zinc;however,current levels remain significantly above Permit
limits. It is very doubtful the Town will achieve compliance with the copper and zinc limits
through additional,affordable improvements at the WWTP;however, further reductions in
metal concentrations are believed possible with further improvements at the WWTP.
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MIT CITY WWTP NPDES PERMIT METALS AUGUST 2022.doc 220803

The Town plans to further investigate ultimate compliance with its NPDES Permit as
follows:
1. Continued study of chemical additives to control and optimize pH control
2. Continued study of chemical additives to reduce copper and zinc
3. Review potential changes in the treatment of the Town's potable water that may
reduce the corrosivity of the potable water,thereby lowering the influent
concentrations of copper and zinc at the WWTP
4. Perform effluent dilution modeling in Calico Creek to support an increase in the
copper and zinc effluent limits
5. Consider relocating the point of discharge further downstream in order to maximize
dilution of the discharge to support an increase in the copper and zinc effluent limits
6. Consider discharging only during periods of outgoing tide to increase dilution to
support an increase in the copper and zinc effluent limits
7. Perform a Water Effects Ratio study to support the need for higher limits based on
demonstration that the metals are naturally occurring, and the aquatic life has adjusted
to higher concentrations of copper and zinc
The Town received funding in the amount of$6,000,000 in July 2022 to assist in the above
work. The schedule for the work is as follows:
1. Hire an Engineering Company to assist with the study and implementation of
improvements to achieve compliance with the NPDES Permit limits on or before
November 2022
2. Engineering Company to complete consideration of items 1 —6 above on or before
December 2023.
3. Completion of plans for WWTP improvements on or before June 2024
4. Obtain construction Permits on or before November 2024
5. Award construction contracts on or before December 2024
6. Completion of construction on or before June 2026
7. Compliance with NPDES limits and project closeout on or before December 2026
It is noted the above schedule will not likely achieve compliance with the copper and zinc
limits by the March 1, 2025 date in the Town's NPDES Permit.
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ME CITY W WTP NPDES PERMIT METALS AUGUST 2022.doc 220803

MOREHEAD CITY WASTEWATER TREATMENT PLANT
METALS
Effluent Influent Effluent Effluent
Influent Copper Nickel Nickel % Influent Zinc Zinc
Date Cu(ugll) (ugh) %Removal (ugh) (ugll) Removal (ug/l) (ugh) %Removal
NPDES Permit Limit 1.85 4.16 42.8
February 6,2018 133 11 91.73% 14 11 21.43% 139 36 74.10%
May 8,2018 97 <10 89.69% 27 27 0.00% 105 23 78.10%
August 7,2018 92 <10 89.13% <10 <10 132 21 84.0956
November 6,2018 56 <10 82.14% <10 <10 80 28 65.00%
March 26,2019 93 <10 89.25% <10 <10 97 36 62.89%
April 2,2019 91 <10 89.01% <10 <10 108 35 67.59%
August 6,2019 100 14 86.00% <10 <10 113 24 78.76%
November 5,2019 93 <10 89.25% <10 <10 102 27 73.53%
February 4,2020 133 11 91.73% 14 11 21.43% 139 36 74.10%
March 3,2020 102 <.01 99.99% <10 <.01 102 35 65.69%
April 7,2020 65 7 89.23% <4.15 <4.15 108 27 75.00%
May 5,2020 79 8 89.87% <4 <4 150 31 79.33%
June 2,2020 68 1 98.53% 2 <1 129 14 89.15%
July 14,2020 101 8 92.08% 3 1 29
August 11,2020 70 8 88.57% 2 2 129 32 75.19%
September 1,2020 99 12 87.88% <4 <4 159 24 84,91%
October 6,2020 137 11 91.97% <4 <4 237 25 89.45%
November 3,2020 92 11 88.04% 7 <4 142 33 76.76%
December 8,2020 167 10 94.01% 5 <4 284 52 81.69%
January 19,2021 68 8 88.24% 2 1 89 46 49.44%
February 4,2021 112 4 96.43% <10 <4.15 226 44 80.53%
March 2,2021 74 69 6.78% <4.15 <4.15 117 40 65.81%
April 6,2021 105 6 94.29% 2 <1 297 62 79.12%
May 4,2021 131 8 93.89% <4 <4 170 35 79.41%
June 8,2021 55 8 85.45% 2 <1 101 33 67.33%
July 1,2021
August 17,2021 76 8 89.47% <4 <4 135 37 72.59%
August 24,2021 106 11 89.62% <4 <4 233 29 87.55%
August 31,2021 <4 <4 122 26 78.69%
September 14,2021 94 8 91.49% <4 <1 218 29 86.70%
October 5,2021 136 10 92.65% 2 <1 179 32 82.12%
October 12,2021 80 9 88.75% 2 <1 161 23 85.71%
October 21,2021 8 <1 27
October 26,2021 93 9 90.32% 2 <1 148 27 81.76%
October 28,2021 8 <1 29
November 16,2021 304 7 97.70% 2 <1 175 28 84.00%
November 23,2021 84 8 90.48% 2 <1 149 27 81.88%
November 30,2021 96 7 92.71% 2 <1 150 25 83.33%
December 21,2021 99 6 93.94% <4 <4 174 29 83.33%
December 28,2021 87 6 93.10% 2 <1 170 28 83.53%
January 4,2022 98 6 94.90% 2 <1 201 34 83.08%
January 11,2022 143 9 93.71% 4 <1 462 36 92.21%
January 18,2022 84 4 95.24% 2 <1 129 29 77.52%
February 1,2022 78 5 93.59% 2 <1 119 32 73.11%
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February 15,2022 102 6 94.12% 2 1 185 31 83.24%
February 22,2022 220 6 97.27% 5 <1 402 42 89.55%
March 8,2022 104 6 94.23% 2 <1 227 32 85.90%
March 15,2022 113 5 95.58% 2 <1 230 27 88.26%
March 29,2022 168 4 97.62% 3 <1 385 33 91.43%
April 5,2022 108 3 97.22% 3 <2.5 321 28 91.28%
May 31,2022 295 6 97.97% 5.3 <1 451 24 94.68%
June 14,2022 104 7 93.27% 2 180 100.00%
June 21,2022 72 6 91.67% 2 151 100.00%
June 28,2022 118 9 92.37% 2.7 249 100.00%
July 5,2022 72 5 93.06% 1.9 116 100.00%
Average 109 8 92.96% 3 1 182 31 82.73%
UPSTREAM AND DOWNSTREAM SAMPLES
UPSTREAM(ugh) DOWNSTREAM(ugll)
Date Cu Ni Zn Cu Ni Zn
March 10,2020 <10 <10 198 <20 <10 42
May 12,2020 3 <2 2 <1
June 2,2020 2 <1 2 <1
July 13,2020 2 1 2 <1
August 11,2020 2 <1 15 2 <1 46
September 1,2020 2 <4 18 2 <4 46
October6,2020 <1 <4 56 <1 <4 12
November 2,2020 1 <4 40 <1 <4 <20
December 8,2020 2 <4 98 2 <4 110
January 19,2021 <1 <1 2 <1
February 9,2021 2 <20 128 <1 <20 25
March 2,2021 4 <4.15 35 <1.85 <4.15 <30
April 6,2021 3 <1 46 2 <1 35
May 4,2021 2 <4 30 3 <4 44
June 8,2021 1 <1 58 2 1 120
October 5,2021 2 <1 51 2 <1 43
January 11,2022 1 <1 93 2 <1 <30
February 1,2022 <1 <1 <30 1 <1 47
April 5,2022 5 1 113 3 1 <20
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