NC0047384_NOI_NOV2021LV0383_Response_20210610

NC Department of
City Of GY'2@11SbOP0 Environmental
ReceivedRuality
J North Carolina Water Resources Department JUN 2 2 2021
Winston-Salem
Regional Office
June 10, 2021 via email and CERTIFIED Return Receipt 7003 1680 0001 0765 8978
Mr. Lon Snider
Ms. Jenny Graznak
North Carolina Department of Environmental Quality -Division of Water Resources
Winston Salem Regional Office
450 West Hanes Mill Road - Suite 300
Winston Salem, North Carolina 27105
RE: NCDEQ May 26, 2021 Notice of Violation and Intent to Assess Civil Penalty
NOV-2021-LV-0383
T. Z. Osborne POTW NCO047384
February 2021 NPDES Permit Violations
Dear Lon and Jenny,
This correspondence is in response to your NOV/NOI certified letter of May 26, 2021 which we
received on June 2, 2021. We would like to reiterate (in more detail) the information•provided
on the February 2021 eDMR and include an update of activities and plant performance. We have
also included information on the violations that occurred in March 2021 and Apri12021. We
appreciate you taking the information provided into consideration as enforcement goes forward
for all of the violations.
As you are aware the City of Greensboro T. Z. Osborne POTW (TZO) experienced several
NDPES permit violations in the February through April 2021 time period. The T. Z. Osborne
Biological Nutrient Removal (BNR) construction project, mandated by the Jordan Lake
Rules/State of North Carolina,-in.additionto issues with the fluidized bed incinerator, have
impacted our ability to meet 9 DES permit limits, particularly under high flow conditions. The
following actions and activities were undertaken in response to the Carbonaceous Biochemical
Oxygen Demand (CBOD), Total Suspended'Solids (TSS), Ammonia Nitrogen, and flow
violations:
Causes of Violations and Remedial Actions Taken
A combined sequence of events resulted in the February 2021 and March 2021 violations: high
flows due to rainfall, contractor construction shut downs, elevated solids inventory, and a
structural failure of the fluidized bed incinerat call contributed to a loss of solids to the effluent
and also impacted the nitrification process

Letter to Mr. Lon Snider/Ms. Jenny Graznak 6-10-2021 re: NOVINOI of 5-26-2021 page 2
February 2021
• The February 2021 flow violation (1 MA), TSS violations (1 WA, 1 MA), CBOD violations
(2 WA, 1 MA) and ammonia violations (2 WA, 1 MA) were all related to an 8-day period
(February 11-18) of sustained rainfall (5.0 inches) that resulted in flows >40 MGD for 13
consecutive days. The TZO flow was >40 MGD 19 out of 28. days in February 2021.
■ The TZO flow February 13'h through 19"' averaged 58 MGD, never dropped below 50 MGD,
and recorded a maximum of 71.5 MGD on February 17d'. During the high flow event, the
operations staff utilized all equalization tanks (total of 11 MG), turned off blowers to save
biomass and solids loss from finals as well as to prevent blinding and possible damage to our
Aqua Diamond effluent filters, and allowed the basement of the influent pump station to
flood in order to provide more flow storage and increased detention time. In addition, two
aeration tanks that had been turned over to the contractor were taken back and put into
service during the event, and two final clarifiers that were being refurbished were
immediately put back in service for flow storage.
• Beginning in December 2020, TZO experienced incinerator issues that resulted in several
unanticipated shut downs and increasing MLSS concentrations. We had approximately 240
hours of down time before we finally had a major failure in the heat exchanger resulting a
complete shutdown of incineration from February 3rd through February 16th. During the
incinerator down time, HILCO was hired to haul sludge to a private landfill in an attempt
reduce solids inventory, mitigate impacts to the treatment processes, and maintain effluent
quality. From February 3`d through February 18d' a total of over 1614 tons (3.23 million
pounds) of sludge was hauled by HILCO at a cost of over $220,000.
Date
Rainfall
inches
TZO Flow
in MGD
TZO Effluent
CBOD mg/1
TZO Effluent
TSS m 1)
TZO Effluent
Ammonia (mg/1
2/11/2021
0.79
45.2
3.74
8.6
3.07
2/12/2021
0.40
49.4
6.33
15.9
3.88
2/13/2021
1.19
60.8
2/14/2021
0.60
55.5
2/15/2021
0.88
54.4
23.7
22.0
12.1
2/16/2021,
0.00
71.5
62.4
139
11.7
2/17/2021
0.25
51.2
82.0
41.0
1 15.4
2/18/2021
0.85
54.9
Snow Day
Snow Day
Snow Day
2/19/2021
0.00
55.6
13.9
13.1
16.0
2/20/2021
0.00
45.5
2/21/2021
0.00
42.4
2/22/2021
0.52
40.4
16.7
27.7
14.3
2/23/2021
0.00
42.6
8.38
14.7
13.0
2/24/2021
0.00
39.6
24.3
91.0
1 10.6
2/25/2021
0.00
41.8
30.3
43.0
18.0
2/26/2021
0.82
45.0
43.2
32.0
26.1
2/27/2021
0.07
49.7
2/28/2021
0.00
43.4
PO Box 3136 • Greensboro, NC 27402-3136 • www.ereensboro-nc.eov • 336-373-CITY (2489) , TTY # 333-6930

Letter to Mr. Lon Snider/Ms. Jenny Graznak 6-10-2021 re: NOY/NOI of 5-26-2021 page 3
March 2021
• In March 2021, TZO returned to compliance for flow, TSS and CBOD, but continued to
struggle with ammonia nitrogen due to still high solids inventory.
■ One MA ammonia violation was recorded (4.85 mg/1 recorded_vs. MA limit of 4.0 mg/1).
April 2021
■ TZO had returned to compliance for ammonia during the 1 st week of the month.
■ The April 2021 ammonia violations (1 WA, 1 MA) and Whole Effluent Toxicity (WET)
violation (Fail at 90%) were caused by higher than usual influent ammonia concentrations
experienced during the 2" d and 3`d weeks of April, resulting in pass -through to the effluent.
■ The April WET test used the composites of 4/20 (ammonia = 7.81 mg/1) and 4/22 (ammonia
= 16.3 mg/1). The test failed due to mortality and reproduction caused by the high effluent
ammonia concentrations. TZO had not failed WET since 2012.
■ The high influent concentrations were traced to Shamrock Environmental, a Significant
Industrial User. A draft Significant Non -Compliance NOV/Civil Penalty enforcement
document has been written and will be provided to NCDEQ upon final issuance.
Compliance Update:
■ There have been no TSS violations since February 2021 inclusive of the date of this letter.
■ There have been no flow violations since February 2021 inclusive of the date of this letter.
• There have been no CBOD violations since April 2021 inclusive of the date of this letter.
■ There have been no ammonia violations since April 2021 inclusive of the date of this letter.
■ Whole Effluent Toxicity test passed in May 2021 at the required 90%.
■ There were no TZO NPDES permit violations in May 2021 and the flow averaged 31.41
MGD (preliminary flow data).
We appreciate the opportunity to present this information for your consideration. If you have
any questions or need additional information, please feel free to contact me.
Sincerely,
'--�a&OTOWM
Martie Groome
Laboratory and Industrial Waste Supervisor
cc: Michael Borchers, Water Resources Director (via email)
Kristine Williams, Deputy Water Resources Director (via email)
Elijah Williams, Water Reclamation Manager (via email)
Bradley Flynt, T. Z. Osborne ORC/Plant Superintendent (via email)
Alicia Goots, Laboratory Coordinator (via email)
Veronica Covert - Files (via email)
Ron Boone, NCDEQ WSRO
PO Box 3136 - Greensboro, NC 27402-3136 • www.greensboro-nc.gov , 336-373-CITY (2489) • TTY# 333-6930