NC0026042_Response to Notice_20221013

RCBERSON`VILLE
tltenee>t a me
October 11, 2022
Mr. Robert Tankard, Regional Supervisor
Water Quality Regional Operations Section
Mooresville Regional Office
Division of Water Resources, NCDEQ
Subject: Notice of Violation and Assessment of Civil Penalty
for Violations of North Carolina General Statute (G.S.) 143-215.1(a)(6)
and NPDES WW Permit No. NC0026042
Robersonville WWTP
Martin County
Mr. Tankard,
Thank you for allowing the Town of Robersonville the opportunity to respond to this Notice of Violation issued October
3, 2022; received on October 7, 2022. Below is our response to the limit exceedance violation(s) that occurred during the
August 2022 monitoring period, for a Total Copper daily maximum exceedance and subsequent monthly average
exceedance, and a fecal coliform weekly geometric mean exceedance.
The first issue we want to explain is the Fecal Coliform weekly geometric mean exceedance accounting for the week of
8/1 — 8/6. The system monitors fecal coliform 5 times weekly. Four of the daily results from the 8/1 — 8/6 period were
>600/100 ml, with the exception of 135/100 ml on 8/2, which was under the daily maximum limit of 200/100 ml. A
rainfall event occurring on 7/31 produced 2.6 inches of rain, which disturbed the plant on 8/1/2022. With the plant
utilizing 24-hour composite sampling, the results reported for 8/1 were mainly accounting for the day of 7/31. Operators
did not receive the fecal coliform lab results until the following week starting on 8/10/2022, nor any notifications warning
of the exceedances (it is typical of our lab to do so). This partially contributed to the repeat exceedances due to being
unable to make any operational changes.
1. 8/1/22 & 8/2/2022 results were emailed on 8/10/2022 of the following week
o C12 8/1/22 was 1.15 mg/I before dechlorination and 48 ug/I effluent
o Cl2 8/1/22 was 1.04 mg/I before dechlorination and 34 ug/I effluent
2. 8/3/2022 results were emailed on 8/22/2022
o CL2 8/3/22 was 0.93 mg/1 before dechlorination and 34 ug/1 effluent
3. 8/4/22 & 8/5/2022 results were emailed on 8/12/2022 of the following week
o CL2 8/4/22 was 0.92 mg/I before dechlorination and 33 ug/I effluent
o CL2 8/5/22 was 0.93 mg/I before dechlorination and 31 ug/1 effluent
Prior to being made aware of the abnormally high fecal coliform levels via the analytical results, operators had no
preemptive indication that fecal coliform was high due to chlorine levels being adequate through the plant as well as at the

effluent. Process control chlorine monitoring is conducted at both the entry and exit points of the chlorine contact chamber
prior to effluent sampling.
A Total Copper daily maximum exceedance occurred on 8/3 with a result of 27 ug/I, exceeding the daily maximum limit
of 17.85, which contributed to violation of the monthly average limit of 13.07 ug/I. We have determined the main
contributing factor to be the discharge received from the Flagstone facility. Effluent Total Copper results received from
Flagstone for August 2022 are as follows:
1. 8/3/2022 Copper 61 ug/I
2. 8/9/2022 Copper 64 ug/I
3. 8/19/2022 Copper 93 ug/1
4. 8/26/2022 Copper 51 ug/1
As was shown, all of them exceed the Robersonville WWTP permit limits.
The Town of Robersonville and the Robersonville WWTP has taken these issues into account to prevent future non-
compliance events. As a corrective action, we have requested that Meritech Labs contacts us as soon as possible upon the
detection of any fecal coliform exceedance violations to allow operators to implement any necessary changes to the
treatment process. It is always our goal to remain in compliance with regulations set forth by the Division of Water
Resources. It is our request that our cooperation and action in these matters be taken into account by the Division when
proceeding with enforcement.
Chris Roberson
Town of Robersonville
CC:
Joshua Powers, Envirolink, Inc.
Chris Roberson, Interim Town Manager
James Duncan, Town of Robersonville