NCG110008_COMPLETE FILE - HISTORICAL_20171222

M,E
STORMWATER DIVISION CODING SHEET
NCG PERMITS
PERMIT NO.
DOC TYPE
lJ� HISTORICAL FILE
❑ MONITORING REPORTS
DOC DATE
❑ a 0 1 -7 1 a a- a
YYYYMMDD

CHARLOTTE
W6TER
December 22, 2017
ATTN: Mr. Wes Bell
NC Division of Water Resources JAN 02 2018
Mooresville Regional Office
610 East Center Avenue Suite 301 k3'M 3ECUION
Mooresville, NC 28115 INFORMATION PROCESSIrNIG I. 1)
Re: Notification of Discharge of Pa tEd Wastewater Final 5 Day Report
NPDES Permit #NC0024945, CG110008
Irwin Creek WWTP, Mecklenburg ounty
Mr. Bell,
Please let this letter serve as Charlotte Water's (CLTWater's) written notification for the discharge of
partially treated wastewater that occurred at the Irwin Creek WWTP on October 26tt at 07:00,
CLTWater's initial communication regarding this event was made via phone call to you on Thursday,
October 25'" at 14:27. Mecklenburg County (LUESA) was also contacted. In response to this event,
CLTVVater has conducted a full investigation and would like to share the following information concerning
the event.
Detailed Summary of Events
Irwin Creek Wastewater Treatment Plant is currently under construction. The Contractor recently
installed new piping to Primary Clarifier 1 and increased the depth of the clarifier by increasing the height
of the clarifier wall, launder, and mechanism. The clarifier was originally built in the 1940's. The structure
has been evaluated in the past and is considered in good condition.
Prior to putting the clarifier back in service, the empty tank was visually inspected for any defects. This
included pressure relief valves around the lower portion of the tank walls that relieve pressure from
groundwater around the tank. The valves were in good working order. Existing cracks in the walls also
were inspected and were deemed to be typical of tanks of this age, and not capable of creating leakage
outside of the tank.
Tank filling and startup occurred on Tuesday and Wednesday, October 24-25. No leakage outside the
tank was observed. On Thursday morning, October 26, operations staff noticed that the ground around
the tank was wet. Further investigations revealed that a storrnwater drain and catch basin in the area had
wastewater flowing into it. The primary clarifier is adjacent to a flood protection dike and is in the
floodway, It is important to note that the stormwaler outfall gate was in the closed position during this
event and that the only water that escaped to the creek was through seepage around the seal of the gate
and through the duck bill. Based on measurements and other observations, it was estimated that
approximately 3,375 gallons of wastewater seeped through the stormwater gate and duck bill and entered
the creek. Upon discovery of the leak, operations staff began to immediately drain the clarifier so as to
prevent any further issues.
Charlotte Water 5100 Brookshire Blvd, Charlotte, NC 2.8216 Charlottewiter.org
01matetr by the City or Charlotte

Mecklenburg County (LUESA) visited the site on Thursday October 26, 2017 at 16:48, the inspector took
upstream and downstream held measurements and they were nearly the same indicating no
impact. Although total discharge volume was 3375 gallons, the rate of discharge was only 9 gallons per
minute since the gate was closed and only what seeped through entered the creek, There was
additional flow in the creek from recent heavy rain that also reduced any potential impacts to the receiving
stream. The report from Charlotte -Mecklenburg Stormwater Services (LUESA) is attached to this letter.
On Friday October 27, Hepaco, an environmental clean-up contractor proceeded to clean all areas that
were exposed to the spill including the storm drain pipe and catch basin. Concurrently, a structural
specialist from the Engineer of Record, Hazen & Sawyer, visited the site to inspect the drained tank to
determine the cause of the leak. No apparent cause was identified with this inspection.
Final Conclusions and Preventative Measures
The contractor, engineer, equipment vendors, and operations staff have collaborated to determine that
the primary cause of the leak was the pressure relief valve(s). The clarifier has remained out of service
during most of this investigation. In addition to the pressure relief valves, a 0.75" water supply line (for
sludge pumping) was faulty. This may have served as a conduit for some leaking, but was likely a
negligible amount.
Once the likely cause was determined, the clarifier was slowly refilled with potable water for testing
purposes. Some additional leaking (of potable water) did occur, but it was all contained on site and
returned to the wastewater treatment process. CLTWater again consulted with various experts, and
determined that pressure relief valves (of the type in this clarifier) may leak when containing only potable
water, but would likely seal when filled with wastewater.
At this point, an additional step was taken to mitigate the risk of experiencing another leak. CLTWater
decided to completely encase (with concrete) the joint where the existing influent pipe and new influent
pipe to the clarifier were joined. This step was completely preventative in nature, since no leaks were
detected at this pipe union.
Prior to refilling the clarifier with wastewater, three sampling stations were installed around the clarifier
perimeter. These have been used to test for ammonia since refilling, and would indicate the presence of
raw wastewater. Results thus far have indicated that no leaks are present. In addition, on 12/06/2017, all
flow was stopped to this clarifier for 4 continuous hours. The water level held steady with no measurable
decrease.
Compliance History
Irwin Creek VVWTP has an exceptional history of compliance with all permit limits and conditions. This
facility was recently designated as an Exceptionally Performing Facility by NCDWR. This affords Irwin
Creek WWTP a reduced monitoring frequency for all conventional pollutants including fecal coliform.
Although we are only required to sample for fecal coliform twice a week we still collect five days of
samples to demonstrate the effectiveness of our treatment process and our commitment to protection of
public health and the environment.
Charlotte Water 5100 Brookshire Blvd, Charlotte, NC 28216 tharlottewater.org
1§ operated by the Clty of Charlotte

Summary
CLTWater takes environmental compliance very seriously and we appreciate the opportunity to provide
information related to this event. If you have any questions concerning the information contained in this
report, or if you need any additional information, please feel free to contact our Water Quality Program
Administrator, Shannon Sypolt, at 704-3364581, or me at 704-336-5433.
Respectfully,
J u line A. Jarrell, P. .
O erations Chief, Environmental Management Division
Charlotte Water
Cc: J. Lockler (CLTWater), M. Lingerfelt (CLTWater), S. Sypolt (CLTWater), R. Hargrove (CLTWater)
Charlotte Water 5100 Brookshire Blvd, Charlotte, NC 28216 charlottewater.org
4B Operated by the City of Charlotte

Attachment 1 — Charlotte -Mecklenburg Stormwater Services Report
chadooQsteUrsvrowQ
STORK 145 SuIIIa Avenue
WATER CharloSte,I1C 1B206.5777
- . Ser-vire Request Re13atI
scrvJccs _
Gerieiallidormatlah ` _ - - . -
RaquestID:22413
Status; CLOSED
Emerganoy: Yes
Initial Call: 10rj5Q017 5:57:55PIA
Initiated By: Barnes, Iva
DaidTlma Init 1=62017 &M03PM
Submit To: MCCULLOC H, JOH N
Dapa@h To: Basnes,Iva
Closed By: MCCULLOCK,JOHN
Date Closed 11WO17 10.07:22AM
Closed In 13 days
_ ,, Gilleianftirrnatton
Caller. UNKNOWN
Address:
Phone Number.
Customer Holllled Yet
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C _ ;Inaldent Infarmatiom _
Addrrt;r. 4070 W ESTMONT DR Chadote - (Sugar C1e 1k)
Type: General Water4wQV Service Request
Problems Found: 1 • Resolved: 1
Cetalls: 1"Altially b cited wastewater entartd Irvvin creek dueto a leak in primary darl1ler 1.
;�•�:,` z:` aosrlectians5ul11ntary ,
Iitsp. tD: Insp. Type Insp. Date: Crstumer, I speotor; Attaohments
33038 General irGpeutil 102012017 4A602AM , Phaset Barnes, Iva 0
Incident type
Aoddtntalspill
bMedla impacted
Stream
Material released
Sewage- CMl3
Investlgalienmelhodsused
Physical
AmountspTed
Gallons
3,375 gallons
Land use type for activity looatlen
Industrlal
Summary:lva Bamet re,pondedle an ER call from Shannon Sypoll(Charlotle Water) regarding aspill of rWillur
wastewater al bwln Creuk W%`TA oa 10l11117. The spilt L believed to be eaLned by a malfunctioning pressure relief
valve in primary clail i fromwhleh seerago leaked through the ground to the nearby storm drain system. There's a
pale in the slormdrain systemseparating it eom the eutfall lhatwas shut, which greatly limited the amount ofsewage
thatwas roltMed to thacreek.lt is estimate d that 3,175 gabons otstwagawas dlschargedto the crttk btforethe
llowwai slopped. The cleanup oonha0or(i1F.PACO)was already onslte vaeuumurgthew" water out al the storm
di sin system. a nd the VMTP was in the process of r emoving ap wiGte wale( tram the m almnOoninp p Iimary clarifier
1 toQrfmary clarlfier 3lvatock ysi ieadlnos both upstream and down (see attached pictures),
�'•�`y�
1111/ To rgpori pollution ur drainage problems call.311
ill
Cll till lrl'1!:
i 1l42UI1 B;r8�3R t1
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Charlotte Water 5100 Brookshire Blvd, Charlotte, NC 28216 charlottewater.org
Rom?' Operated by the City of Charlotte

Imp.1q: - Insp';Type; Insp. Gaic Customer; Inspeolor; Attachment%
MWV Geneoal lnipe'ctlon, 11AJ�017 11:00i(D7AM-Phaiel Barnes, Iva �.
Investigaiionmtthodsused I Physical
Summary: Iva Barnes mat Shannon Sypottat Irwin Credr WVVTP on 1117117. An investigation G still underway
regit&ng the iaited primary claritlar. Cuirenty, and untathe cause oftheleak Is determined and corroded, primary
olafller 1 is not in use. I&. Baines Inspectedthestormwatersystom nearby the tailed primary clarifier and observed
that thastorm water gate was slillshut and no oat of is being discharged to the oretk. As a pad of tha tasting,
potable water G being run through the system and Is pomp vacuumed Out before reaching the stat m water gate. Any
storm water from a rain oventwgl Ikewise he vacuumed out of the storm water system. Ms. games took aysireading
at the oultail and observed ndhIng cut of the ordinary. Plant officlab wIG continue to investlgale the tailed primary
clarifier to determine the cause of the It& Their findings will be shared and attachi dtothc service request once they
are avallaWe. No further action necessary.
e
To report pollution or drainage problems calk 311
http;l/slormwater.ch arms ch.ofg
t:.II lI1tIJE'll'.
11MOIT a.re2a+o
Charlotte Water 5100 Brookshire Blvd, Charlotte, NC 28216 charlottewater,org
tin Operated by the City of Charlotte