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Water Resources

CSO Control in BTV

Burlington has implemented a variety of measures to reduce combined sewer overflow events from our collection system.

Each year, the City submits an annual report to the Vermont Department of Environmental Conservation outlining how we meet the 'Nine Minimum Controls' required by the Vermont Combined Sewer Overflow Rule and the U.S. Environmental Protection Agency (EPA).  Copies of Burlington's annual reports can be found by clicking the tiles below.  

The following table outlines the central compliance efforts Burlington utilizes to meet the Nine Minimum Controls.

How Burlington Complies With the Nine Minimum Controls


Minimum Control 1:

Proper operation and maintenance programs for collection system and CSO outfalls

The City maintains a detailed Collection System Operation & Maintenance Plan.  This plan outlines the levels of service, prioritization, critical locations, and routine maintenance activities on Burlington's collection system.

Minimum Control 2:

Maximum use of the collection system for storage without endangering public health or property, or causing solids deposition problems

The City has installed a number of storage structures to attentuate flows to our combined sewer system, including:

  • 1988:  Install of a ~100,000 gallon capacity storage pipe adjacent to Englesby Brook
  • 2000: Install of twin ~180,000 gallon capacity box culverts at the top of College Street
  • 2010: Install of two 5,000 gallon capacity off-line storage tanks on South Prospect Street


Minimum Control 3:

Review and modification of pretreatment requirements to assure that CSO impacts are minimized

Burlington has been developing an Industrial Pollution Prevention Program since 2019.  

Minimum Control 4:

Maximization of flow to the treatment plant for treatment consistent with an evaluation of alternative treatment options

Burlington has 3 wastewater treatment facilities, each of which serves some portion of the combined sewer system.  Starting in 1988, all 3 plants were upgraded and significant portions of the combined sewer system were disconnected. Main Plant still collects the largest portion of combined sewer area in the City, and was designed with dedicated wet-weather treatment for this reason. 

Several of the overflow weirs in our CSO manholes have been raised in order to redirect more volume to the wastewater treatment plants and minimize both the frequency and duration of overflows.

Minimum Control 5:

Prohibition of CSOs during dry weather

Ongoing routine maintenance is intended to reduce the likelihood of dry weather overflows in the combined sewer system.  While occassional clogging does occur, emergency response protocols have been effective in mitigating overflows during dry weather.

Minimum Control 6:

Control of solid and floatable materials in CSOs

Catch basin hoods are employed in structures with adequate space to accomodate them.  There are miscellaneous orifice plates and other control devices installed throughout the collection system.

Annual catch basin cleaning efforts further contribute to the control of solid and floatable materials in CSOs.  The City has also been supporting Green Up Day efforts from the beginning of that program.  Green Up Day, ongoing street sweeping efforts, as well as the statewide ban on plastic bags have contributed to a significant reduction in debris to our collection system.


Minimum Control 7:

Establishment of pollution prevention programs to minimize contaminants in CSOs

Burlington Public Works has operated a street cleaning program for over a decade.  Burlington DPW further provides recycling collection services to residents and businesses throughout the City, which has been mandatory since 1992. Burlington's recycling program diverts and estimated 5.9 million pounds of recyclables from the landfill each year.  


Minimum Control 8:

Public notification to ensure that the public receives adequate notification of CSOs and CSO impacts, which shall, at a minimum, comply with §34-404 of [the Vermont Combined Sewer Overflow Rule]

Each of the City's CSO outfalls is marked with permanent signage, which identifies the outfall and warns of the potential threat to public health posed by recreating nearby.  Burlington also has a Standard Operating Procedure in place to ensure notifications are made consistent with State law.  

The City uses several platforms to issue required notifications to the public, including VTAlert, social media (Facebook, Twitter), and Front Porch Forum.


Minimum Control 9:

Monitoring to effectively characterize CSO impacts and the efficacy of CSO controls

The City maintains up-to-date GIS data on our collection systems.  Public facing maps are available on our website here.

All 5 of the City's CSO structures are equipped with Mission monitoring devices, which notify staff when an overflow is occurring, and records the duration of the overflow.  All 5 of these monitors were upgraded in 2021.




Annual Reports

CSO Mitigation Projects