WQ0029945_NOV-2019-LV-0814 Response_20191112

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ONWASA
onwasa.coM
228 Georgetown Rd
Jacksonville. NC 28540
November 12, 2019
Morella Sanchez -King, Regional Supervisor
Water Quality Regional Operations Section
Division of Water Resources, NCDEQ
127 Cardinal Drive Extension
Wilmington, North Carolina 28405
RE: Notice of Violation
Tracking Number NOV-2019-LV-0814
Summerhouse Wastewater Reclamation Facility
Permit No. WQ0029945
Onslow Water and Sewer Authority, Onslow County
Ms. Sanchez -King:
This letter is sent in response to the October 31, 2019 Notice of Violation (NOV) issued
by your office for Limit Exceedance Violations that occurred at the Summerhouse WRF during
the month of August 2019.
While ONWASA does not dispute the occurrence of the three events listed in the NOV, as
they were self -reported, we believe the problem can be attributed to certain operating conditions,
coupled with ongoing problems in cleaning the microfiltration membranes during this time period.
This was highlighted in email correspondence between ONWASA ORC Mike Lutz and Helen
Perez of NCDEQ at the end of August 2019:
On 8126119 Summerhouse had a fecal exceedance of 25.9 MPN. 1 believe this has to
do with putting one of the trains back online earlier in the day. As we discussed
yesterday, the effluent pit has an average volume of about 3, 000 gallons under normal
operating conditions. The trains only run about 40 gpm normally, so with two running,
that leads to just about three hours to turn the pit over three times. Train 2 was put
online at 1000, and the sample was pulled at 1250.
When a train is brought online, it takes at least 5 minutes for the UV to "Ready". This
results in 200-300 gallons of non -disinfected filtrate entering the effluent pit. The
SCADA programming sends the effluent to the upset pond during this time and for a
set time after UV is "Ready". This is currently 15 minutes, 1 believe. We used to have
access to adjust this timer, but with our new HMI, it was not added. 1 am going to get
this added as soon as we can.

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November 12, 2019
The membranes have been having some issues with clogging, and the past two
months they have been taken offline for extended periods to facilitate membrane
cleanings. They have not been recovering like they should, which has resulted in
having to clean them every two weeks. It takes 3-5 days to complete the
cleanings. Since this has been going on, we have had difficulty's keeping the Total
Phosphorus under 2 mg/L. We will likely not be able to meet our limit for total P this
month. There is a technician from Evoqua, the membrane manufacturer rep., coming
to inspect our membranes and give a recommendation in the coming weeks. I will
keep you updated with the progress.
Since this communication, the Evoqua technician has been to the site and provided direction on
both physical and chemical membrane cleaning efforts. To date, this has resulted in an improved
functionality of the membranes that should greatly reduce cleaning frequency and ensure more
consistent train operation.
Thank you for your consideration of this supplemental information. Pease contact me
directly at [phone] or dmohr(o-)onwasa.com you have any additional questions.
Sincerely,
9-44,1 4 10�5—
David M. Mohr, P.E.
Engineering Director
Onslow Water and Sewer Authority
C: Jeff Hudson, Chief Executive Officer
Eddie Caron, Utility Superintendent - Wastewater