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Town of Hartford - Quechee Wastewater Treatment Facility
Incident Report Timeline
03/24/24 to 03/29/24
Sunday March 24, 2024:
Roughly 7:00 am. Both blowers were making atypical noise. Opened the building’s internal door and observed nuisance smoke. An olfactory observation of lightly burnt rubber was present. The operating temperature gauges for each unit nearly peaked at 180° F. The discharge pressure was at its’ peak of 15 psi. The vacuum remained at zero. Immediately both blowers were shut down. The three windows were opened for ventilation and cooling.
Monday March 25, 2024:
The exterior panels of both blowers were removed to initiate visual inspection.
Occasional short duration ‘power-on’ cycles were performed to diagnose the cause.
Phone calls were made to various vendors.
Both electric motors were greased. Note there are 2 zerk fittings per electric motor. The blowers are lubricated by oil bath (no grease zerks).
The blowers remained “Off” for the entire day.
Tuesday March 26, 2024:
Continue calls with vendors and repair companies.
The cause was initially thought to be worn/faulty blowers.
Subsequent investigation found that the electronically controlled air valves were not operating at the proper times. The operators were unable to reprogram the timing,
At the end of the day, blower #1 was restarted after checking the discharge air valve position. The automatic air valve was found to be in the ‘open’ position as needed for the current treatment process. The blower was restarted and ran within normal parameters indicating it was operating as designed. It was left on overnight.
Wednesday March 27, 2024:
Upon arrival blower #1 was again exceeding its operating parameters and shut down.
The automatic valve air had returned to operating on a schedule inconsistent with the treatment process.
A site visit by VT DEC (Garrett Walsh) was performed.
A ‘Discharge of Partially Treated Wastewater’ notification was submitted at 10:30 am.
All electronic control to the air valves was disconnected and the valves were operated manually.
A replacement control panel in the main building was shipped via overnight delivery service.
The blowers remained “Off” for the entire day.
Thursday March 28, 2024:
VT Rural Water (Elijah Lemieux) visited at the request of the VT DEC (Michelle Kolb).
Around 9:00 am, the replacement display panel was installed. No system changes were observed.
Spoke with multiple vendors and forwarded them photos as needed.
At roughly 11:00 am, by happenstance, an Operator observed and replaced a small back-up battery to the PLC. Within one minute, the entire system corrected itself. The Operator was able to reprogram the necessary parameters and the treatment processes were functioning as designed.
Friday, March 29, 2024:
Following visual inspections in the morning of the tank contents (color/clarity), mechanical equipment, (atypical noises), all indications point toward proper system operation. We are satisfied that all of the effluent from the plant has received 100% treatment.
We await the delivery of replacement blower oil. It will be changed immediately. We noted a slightly darker than typical oil in the observation window. We anticipate a very short oil change interval (roughly 50 hours) then returning to the manufacture’s oil change interval recommendation.
Routine daily in-house testing and analysis indicates that the processes are having the desired effects.
General Notes:
From the initial discovery on Sunday morning to the final determination that the facility was discharging 100% treated water as required, QWWTF estimates 1.2 mg of partially treated wastewater was discharged at the permitted outfall (001). Note that all of the partially treated water passed through the active Ultraviolet Disinfection system, which aided in killing a majority of the bacteria. No laboratory samples were collected.
The Operators record each of the blower’s motor hours, operating pressures, temperatures, and vacuum on a daily basis. They are physically in the blower building to obtain these values. Each Operator is very familiar with the pitch of the motors.
The two blowers are not equipped with standard pressure relief valves. Each unit has an ‘over temperature’ electronic switch which we believe is intended to shut down the blower should the exhaust air temperature exceed a set point. It is unlikely these switches are working. A Technician will need to be on-site to inspect/clean/repair/replace these switches. At that time, we will inquire about installing a typical relief valve on each unit.
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