PUBLIC WORKS’ STATEMENT ON INTENSE STORM OF JULY 25TH
- WASTEWATER PLANT PERFORMED WELL & WITHIN PERMITTED LEVELS
- CSO POINTS DISCHARGED: VAST MAJORITY STORMWATER
- BLANCHARD BEACH & BLODGETT ACCESS AREA POSTED WITH CAUTION SIGNS
- DUE TO VOLUME AND INTENSITY OF THE STORM, EFFORTS ARE UNDERWAY TO EVALUATE OTHER CRITICAL COMPONENTS OF THE COLLECTION SYSTEM
Burlington, VT - During last night’s intense storm event – qualifying as a greater than “10 Year Storm” over a 30 minute period - Burlington's Main Wastewater Treatment Plant performed well and all test results so far have been within permitted levels. The plant treated and fully disinfected more than 12 million gallons of stormwater and wastewater last night alone – far more than the average daily flows of 3-4 million gallons. While the plant has historically run without operators during off-hours (though, with operators on call), due to recent equipment and process challenges the plant was staffed throughout last night’s storm.
The intensity of the storm event did cause Combined Sewer Overflows (CSO) at four points, including at Manhattan Dr and Park St (which discharge into the Intervale wetlands), Colchester Ave, and into the Pine St. Barge Canal. These releases are predominately stormwater with a small wastewater fraction. The largest CSO release last night, at a measured 65,702 gallons was at the Pine St Barge Canal. The estimated stormwater component was 91% of the release. The CSOs from the Pine St Barge Canal discharge through a settling pond and then into the canal.
Signs indicating the potential for increased bacteria levels have been posted, out an abundance of caution, at Blanchard Beach and Blodgett Access Area due to their proximity to the Barge Canal. Vulnerable populations, including infants, toddlers and those with compromised immune systems should take caution before recreating in those waters. All other beaches remain open and unposted. As part of Parks, Recreation and Waterfront (PRW)'s normal sampling protocol, Blanchard Beach was sampled today. Additional sampling at other nearby points have also been taken. Sample results will be available tomorrow.
Burlington Combined Sewer Background: An overall reduction in number of CSO points & discharges
Burlington is one of 800+ communities throughout the United States on a combined sewer system - built decades ago. These systems do have a significant benefit of fully treating stormwater during low and moderate rainfall events. Combined sewer systems were designed with downstream relief points to discharge stormwater and wastewater when the flow volume exceeds the carrying capacity of the pipes. This prevents sewage from backing up into homes and businesses. Burlington's CSO points are down to 5 from 12 in the 1990’s, with less frequent discharges.
Approximately 35-40% of Burlington remains on a combined sewer system, mostly located through the downtown core. Burlington treats and disinfects an average of 170M of wet weather flow at its treatment plants annually. Prior to the mid 1990's $50M investment to upgrade the treatment plants and separate much of the sewer system, this flow would have discharged directly to area water.
Ongoing Efforts & Next Steps in Managing Stormwater & Wastewater
We will be bringing an infrastructure plan with projected costs forward to the public and City Council later this year.
Efforts already underway to reduce the stormwater load on our combined system include:
- We have continued designing and installing stormwater infrastructure in City projects, including a recently installed subsurface stormwater infiltration system on Park St this year.
- We will begin in the next two months a comprehensive upgrade of two blocks of St Paul St with robust stormwater infrastructure (soil cells, permeable pavers, rain gardens and more)
- We are also underway with enhanced Illicit Discharge Detection & Elimination efforts.
- Our permitting strategy for local development continues being proactive by requiring new developments to manage 100% of new impervious surface stormwater and requiring larger projects to take additional stormwater off the system to offset their projected wastewater flows (such as for City Place Burlington and Cambrian Rise).
Some other recent efforts to address our wastewater infrastructure include:
- In response to the discharge on July 10, we immediately rewired the disinfection system as the failure was due to a programmable logic board failure.
- We have been engaging with wastewater experts since April, including a national and state expert.
- We are in the process of hiring independent firms to evaluate Main Plant’s computer control system and the rest of the disinfection system.
- We have expanded staffing during off-peak storm events at the Plant.
- We are working with breweries and cideries within the City to reduce the strength of their waste stream.
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