NC0085812_NOV-2019-LV-0920 Response_20200106

Department of Public Works
WaterNVastewater Division
4600 Goldmine Road
Monroe, NC 28110
T. 704-289-1434
F. 704-289-7395
www.unioncountync.gov
January 6, 2020
W. Corey Basinger,
Regional Supervisor
NCDEQ
610 East Center Avenue, Suite 301
Mooresville, NC 28115
Dear Mr. Basinger,
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MOORESVILLE REGIONAL OFFICE
This letter is in response to NOV-2019-LV-0920, outlining exceedences in both monthly flow
and weekly fecal that were experienced at our Grassy Branch WRF in March 2019. These
exceedences were a result of continuous, high rain events in the system.
In our meeting on 05/02/2019, we detailed our efforts in reducing the I&I that is entering the
Grassy Branch collection system. Since that meeting our Collections team has continued
working to improve the system. Such efforts include:
• Smoke testing
• Camera work and jetting
• Visual inspections during rain events
• Manhole rehab
• Installation of inflow collector dishes
We are also wrapping up a comprehensive flow monitoring study by Frazier Engineering. This
study will give us more than 12 months of data, including both dry and wet season flow
characteristics. Once we evaluate this data, we will then start micro -monitoring to pinpoint areas
in the system that could profit from future repair/rehab efforts.
In addition to the I&I reduction, we are in the process of finalizing our application package for a
Special Order by Consent as addressed in our 5/16/19 letter. We contracted with Hazen &
Sawyer Engineering to develop a stream model which has since been approved by NCDEQ.
Using this information, the engineers then designed upgrades to the facility which will alleviate
the issues causing these exceedences. These upgrades would include:
• Anew .070MGD treatment train that would bring total plant capacity to .120MGD
• Cloth -disc filters
• New UV system sized for both trains
• Significant changes to the influent pump station
• New, larger blowers

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MOORFSVILLF RM-110NAL OFFICE
We intend to continue our efforts finding and reducing the I&I in the Grassy Branch basin even
as we address the treatment/capacity issues at the Grassy Branch WRF. If you have any
questions or concerns please contact me at 704-296-4215.
Sincerely,
A=rew N`7
Water & Wastewater Division Director
Cc: Hyong Yi, Public Works Administrator
Josh Brooks, Asst. Div. Director, Water & Wastewater
Bart Farmer, WRF Superintendent
Greg Morgan, Utility Services Superintendent
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