NC0021211_NOI_NOV2024LV0471_Response_20240617

EnN r Dopartment of
G R A H A M Received
JUN 17 2024
Winston-Salem
Regional Office
June 12, 2024
Certified Mail No. 9589 0710 5270 0223 2205 89
Lon T. Snider
NCDEQ\DWR
450 West Hanes Mill Rd., Suite #300
Winston-Salem. NC 27105
Subject: Tracking No.: NOV-2024-LV-0471
Limit Exceedance Violations — March 2024
City of Graham
NPDES Permit # NCO021211
Alamance County
Dear Mr. Snider:
The City of Graham received a notice of violation and intent to issue a civil penalty for
limit-exceedance violations of our permit in March 2024. The City of Graham requests that you
consider the following response in your decision process before taking enforcement action.
The violations are centered around a rain event that occurred in the last week of March.
Rainfall received during this event totaled 1.96 inches.
On the morning of March 27, 2024, rainfall began at the WWTP prior to 7:00 AM. At
approximately 12:00 PM, plant personnel went on High Flow S.O.P. due to elevated flows
entering the plant. Plant personnel had already been running larger recirculation pumps ahead
of the high flows in an effort to reduce solids in our secondary clarifiers and return them to our
Extended Aeration Basin to prevent them from escaping to our Effluent Basin. Throughout the
day, Influent flows continued to increase, exceeding 8 MGD for over an hour and occasionally

spiking to over 10 MGD during that time. Despite the operating of large recirculation pumps
earlier in the day, sludge blanket levels were exceeding 10 feet in all secondary clarifiers by this
time. Due to the excessive rainfall and high flows, solids did escape our secondary clarifiers into
our Effluent Basin creating an upset in our process. The plant finally came off of High Flow S.O.P.
at 5:00 a.m. on Thursday, March 28.
All of our available pumps were fully operational during this rain event. However due to
ongoing construction, only one of our Extended Aeration basins was available during this rain
event. Also, one of our secondary clarifiers was out of service due to a mechanical failure.
Prior to this rain event and plant upset, weekly Total Suspended Solids and BOD results
for the plant had both been well under our permit limits through March. Total Suspended
Solids for the month prior to the March 27 rain event were at 8.3 mg/L, well under our monthly
limit of 30.0mg/L. Even with additional sampling in the last week of March, our weekly and
monthly averages for Total Suspended Solids were still exceeded.
Beginning May 28Ih, the plant came online with one of the new BNR basins. We have
seen much -improved results and are encouraged that the 84 million dollar investment the City
of Graham has made in this new treatment process will continue.
Based on the information provided herein, the City of Graham requests that
enforcement action not be taken for these Limit Exceedance violations. Thank you for your
consideration in this matter. Should you have any questions please contact me via email at
tmannPcitvoferaham.com or by phone at 336-570-6721.
Sincerely,
v `.
Tonya Mann
Utilities Director
Cc: Aaron Holland, Asst. City Manager
Cris Routh, Wastewater Treatment Plant Superintendent