Winooski River Sewer Break Incident Response

Update 11/9

The Winooski River sewer siphon break has been repaired and as of yesterday, November 8, is operational and conveying sewage to the North Waste Water Treatment Plant.  

After 5 weeks of work our contractor, ECI, and DPW Water Resources’ project management have successfully re-built the broken siphon pipe in the river and diverted all wastewater flows from the temporary on-ground bypass system and restored flow back to the sewer siphon that runs under the Winooski River.  

We anticipate that at least 75% of this project and other emergency response efforts will be covered by FEMA funds with an additional 12.5% covered by the state – a significant savings for local ratepayers. Thus far, the overall repair cost is approximately $833K with a total of $1.7M spent on this repair work, earlier emergency sewage hauling, temporary forcemain construction and other costs related to the July 12 sewer break. 

We are also underway with designing a longer-term and climate-resilient alternative to the current 1950’s era Winooski River design. Given the torrential rains of this past summer – which led to the breaks on this river pipe – we are looking at all options that can safely handle all waste flows and better withstand the impacts of a changing climate.  

Description of work:  

The City executed a contract with ECI to perform a design-build repair of the broken sewer siphon. The scope of work included commercial diver inspections of the siphon, replacement of the broken sections of siphon pipe near the North WWTP and assistance with dye testing and commissioning the completed siphon to bring it back online. Upon contract execution the commercial dive inspectors completed another inspection in the river which revealed compromised joints stretching approximately 120 feet from the shore line. The contractor utilized a strategically coordinated combination of divers, barges, stick excavators and a crane to remove and replace the compromised pipe sections  

Why not keep waste flows away from the Winooski River and continue to use the on-ground system? 

While wastewater pipes are less susceptible to freezing than water pipes, the risk is still present. Diverting flows back to the newly repaired river system will limit the risks of operating a pipe at ground-level in Vermont’s harsh winter. Additionally, there is noise and disruption associated with the bypass pipe which we can limit by de-commissioning it.  

The break happened in July. Why did it take until now to fix the river pipe? 

One of the first steps we needed to complete was an evaluation of the condition of the pipe that was in-river. We wanted to ascertain how many breaks there were, how large and where they were. The river had extremely high flows and was very murky for weeks after the torrential rains. We could not safely get a diver into the river until late summer to confirm the condition of the pipe, which was necessary for us to put forward the best temporary repair plans. 

When will you remove the on-ground bypass pipe? 

To stay prepared for unforeseen issues with our newly rebuilt pipe, we will be leaving the bypass system up – though in a non-operational state – as we monitor the performance of the river pipe. If all goes as planned, we will remove the bypass system in spring of 2024. 

How will you prevent this from happening again? 

Given the impacts of a changing climate, there will always be risk present in managing infrastructure. We are working with a consultant to evaluate climate resilient alternative to continuing to rely on an in-river siphon for sewage conveyance.  These include redundant directionally drilled pipes underneath the river bottom or a permanent pump station and underground forcemain that is entirely away from the river.  We continue to evaluate all aspects of our system – and with available funding – implement best practices for all repairs or replacements.  Thus far, FEMA has indicate that a climate resilient permanent repair to the siphon would be eligible for FEMA funding. 

Update 10/18

The City has signed a contract with ECI to perform a Design-Build repair of the existing siphon.  On 10/5/23 ECI’s subcontractor, M&K Divers, performed a dive inspection to locate the breaks in the siphon and on 10/9/23 ECI mobilized to North Plant to begin the in-river repair of the siphon.   The repair will take approximately a month to complete utilizing a combination of divers, stick excavators, a barge and a crane to perform the work.. The City is also working with a consultant, Stantec, to evaluate climate resilient solutions to the siphon repair. The City is continuing to work with FEMA to aid in funding all of the projects. The temporary bypass pump station continues to operate.  

Since the last update there have been a couple of temporary pump station issues that were reported to the state and resolved.  On 9/29/2023, a leak in the plugged outlet at the temporary pump station allowed a small amount of wastewater to leak into the river siphon; it was sealed.    On 10/7/2023, there was an overflow to the river from the temporary pump station due to a large amount of rain, both pumps were running but could not keep up. 

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Update 9/20 part 2

At around 2:45pm on 9/20, the alarms on the North Plant’s temporary sewer force main bypass went off.  Staff immediately responded up to the location of the force main pumps.  There was a discharge into the river for about 30 minutes – roughly projected to be ~12,000 gallons. Staff determined that the floats had failed. These were replaced and the issue is resolved.

Update 9/20 part 1

 DPW had a commercial diver inspect the broken siphon pipe on 8/17. Due to continuous wet weather conditions, the pipe was not still not visible. Inspection was completed by feel and findings were provided to DPW.

DPW is working with FEMA and through City procurement policies to hire a design-build contractor for the repair of the existing siphon so it can be placed back online before winter. DPW has also procured a consultant to review and design a long term, resilient alternatives for the contributing siphon sewershed.

 

Update 8/9 (also shared via FPF)

On Tuesday August 1st, DPW conducted its second non-toxic dye test on the broken sewer pipe under the Winooski River. Over two tests, we have introduced this dye from both sides of the broken line. This has helped us pinpoint the probable location of the break – which appears to be just off shore nearest to the North Wastewater Treatment Plant.

Unfortunately, with ongoing rain, the water has been too turbid for an on-site/in-river inspection. Once water conditions become clear and safe, we will have divers inspect this pipe. We have already released a 'Request for Qualifications' for additional engineering services to fully evaluate repair options for a long term, more climate resilient system.

We do want to report that during two recent rainfalls on 8/4 & 8/7, the bypass system did overflow sending a very small volume (~1 to 5K gallons each time) of untreated wastewater into the River. While our secondary pump did kick-on and alarms alerted crews to respond within 15 minutes, the backup pump was not able to fully handle all the additional storm flows. We are continuing our analysis of flows, capacity and equipment to determine if there are other redundancy options that can be put in place.

In addition to water quality & natural resources stewardship, ratepayer affordability is our priority. Given the official disaster declaration, it is anticipated that at least 75% of the mitigation costs (pumping/hauling & temporary bypass construction) will be covered by FEMA with the City and State splitting the remaining 25%. The amount of FEMA reimbursement may increase. We are paying careful attention to the steps we need to take to minimize this impact to ratepayers.

We look forward to sharing more information in the coming weeks, as well as appearing at the Ward 4/7 NPA on August 10th. Please email water-resources@burlingtonvt.gov with questions or call 802-863-4501 with urgent questions. You can also visit http://burlingtonvt.gov/water to see all of this information and prior updates on our Incident Response Page.

The image below shows the non-toxic dye after introduction to the system. This helps us determine the break is likely just off-shore.

The image above shows the non-toxic dye after introduction to the system. This helps us determine the break is likely just off-shore.

UPDATE 8/1

Today, DPW's Water Resources team is conducting a non-toxic dye test on the broken sewer line in the Winooski River. This test will help us locate where the break - or breaks - may be, and how significant they are. This information aids our planning for short and long term repair options on this pipe - which is underway.

 

Please note, the water in the immediate area of the dye introduction may turn yellowish/green. This is not harmful to water quality. If you have any urgent concerns, please call 802-863-4501. Otherwise, please email water-resources@burlingtonvt.gov. #btv #vt

 

Visit burlingtonvt.gov/water for more info on our response to the Winooski River sewer break. 

 

UPDATE 7/28 (also sent via FPF)

We want to offer an update on the sampling results and reopening of the North Shore Lake Access Areas, the reduced conservation request for New North End residents, and a brief update on the solid performance of our temporary bypass sewer system.  

***LAKE ACCESS AREAS REOPENED***:  As of this morning, we have removed the ‘no swimming’ signs at the 4 northern Lake access areas in Burlington that were within 1 mile of the sewer break in the Winooski River. We tested all 4 locations, and all are well under the EPA recreational standard for E. coli of 235 cfu (these test results range from 3.1 near the North Shore Natural Area to 39.9 colonies/100 mL near the mouth of the Winooski River).  The map of the general location of these areas is available on the incident response page at burlingtonvt.gov/water.

You can also find on-going sampling results from Burlington’s public beaches (which does not include these North Shore Access Areas) at BPRW’s website at enjoyburlington.com. During summer months, they test these public beaches for E. coli twice a week and monitor for cyanobacteria daily.  

While unexpected, we do want to caution the public that if we do experience any discharges (such as during high rain events) from this temporary line, we would have to close access to these 4 northern access areas for at least another 48 hours. 

***CONSERVATION REQUEST***: Our temporary bypass sewer handled its first test well, as designed, with yesterday’s rains. We still would like to strongly encourage conservation during peak hours from 6-8AM and 6-8PM, along with during any intense rainfall, until the permanent sewer is repaired or replaced. Please limit what goes down drains or toilets during these times if you happen to live in the conservation area (see map at burlingtonvt.gov/water).  

**BYPASS SEWER PERFORMANCE**: As of today, our temporary bypass system is performing as designed and rerouting all untreated flows directly to North Plant for full treatment. The system is outfitted with a backup pump, sensors and an alarm that will notify staff if the volume of wastewater exceeds what the pump can handle. We continue to monitor the ability of this system to handle stormwater inputs (for the areas which are still a combined sewer system) and re-open previously closed storm drains where  

**REPAIR PROGRESS**: This week’s non-toxic dye test to more fully characterize the sewer break extent has been rescheduled for next week due to the rain. We have already conducted one round of testing, and this second round will give us even more information as we continue to evaluate all possible short and long term repair/replacement options. Once the dive team indicates the water is safe and clear enough for them to inspect the broken pipe, we will have even more information to move the repair plans forward.  Staff have developed a request for qualifications for an engineering consultant to assist with evaluating various options for a permanent climate resilient repair and hope to release this next week.  Additionally, staff are staying in regular contact with FEMA representatives to ensure the City is able to access as much emergency funding as possible to minimize the impact to ratepayers.   

**STAY INFORMED**: We encourage the public to sign up for VT-Alert at burlingtonvt.gov/btv-alerts and check our incident response page for updates at burlingtonvt.gov/water.  

**QUESTIONS**: Email us at water-resources@burlingtonvt.gov or call 802-863-4501 with urgent questions. 

UPDATE 7/25 (also sent via FPF)

As of approximately 11 AM on July 25th, DPW’s Water Resources team activated a temporary bypass sewer, effectively rerouting all wastewater flows from a broken sewer line that runs under the Winooski River directly to North Plant for treatment. This line is expected to handle 100% of wastewater flows with the possible exception of large rain events. Evaluation and monitoring of the new system is underway to test its performance and re-calibrate pumps, as needed. We expect to reduce our enhanced conservation request for New North End residents soon, updates on this can be found on burlingtonvt.gov/water. 

 

REDUCING + REROUTING WASTEWATER FLOWS: 

Upon learning about the Winooski River sewer break on July 12th, DPW Water Resources mobilized immediately to begin mitigation and repair plans. DPW, along with their contractor BP Wastewater, began pumping and hauling wastewater 24/7 from the broken line to North Plant for full treatment - one day after the sewer break. This increased treated flows to 75% of average North Plant flows. 

 

DPW’S other contractor, ECI, then began mobilizing to build a temporary sewer bypass system on Friday July 14th - 2 days after the sewer line break - and began construction on Monday July 17th. The system includes over 5,000 linear feet of pipe running on-ground from the interceptor point just north and west of Plattsburg Ave and south of the Winooski River – directly to North Plant. The wastewater is now receiving full treatment. To overcome gravity and terrain changes, a bypass pump is in place at the flow interceptor point. This system is outfitted with a backup pump, sensors and real-time alarms that alert staff if wastewater levels were to exceed the capacity of the system to fully reroute this water. 

 

DPW leadership briefed the Burlington Board of Finance on July 17th and the full City Council on July 24th. At this time, costs related to the pump & haul operation and the temporary bypass project are expected to exceed $750K. The City is working closely with state, federal and general partners to secure all available disaster relief funds. 

 

 

REPAIRING THE PIPE: 

DPW has inserted non-toxic dye into the broken sewer line to help determine the extent and location of the break. They are conducting another dye test later this week while also awaiting confirmation from a dive team when they can safely inspect the pipe. Water levels have been too high and water clarity has been too murky for a safe physical inspection of the pipe in the River. Following these steps, DPW will continue planning for short and long-term repairs.  

 

WHAT DOES THIS MEAN FOR SWIMMING? 

 

Burlington Parks, Recreation & Waterfront (BPRW) conducts E. coli testing twice a week at its public beaches. Thus far, they have not had to close these beaches for high E. Coli since the July 12th sewer line break. Visit enjoyburlington.com for updates and sample results. 

DPW expects to sample the North Shore Access Areas in Burlington and will share those results. Once tests show E. coli levels below the EPA standard - and at least 48 hours from today’s rerouting of wastewater flows from the Winooski River - DPW and BPRW will re-open swim access to these areas. Results will be available at burlingtonvt.gov/water. The public can also visit https://colchestervt.gov/ for more information on Colchester’s public beaches, some of which have shown higher E. coli results after the deluge of recent rains and shortly after this break.  

 

While the temporary bypass project is expected to handle 100% of wastewater flows during most circumstances, there is potential that during anomalous rain events it won’t be able to capture all flows. In these cases, it is likely that public access areas will need to be closed for at least an additional 48 hours following any of those discharges. 

WHAT DOES THIS MEAN FOR WASTEWATER CONSERVATION? 

 

It is always a great idea to conserve wastewater and use thoughtful practices, though we expect to reduce our enhanced conservation request for New North End residents soon.  

We will be monitoring and evaluating the performance of this temporary bypass system. If it performs as expected, we will likely reduce our conservation request, but still strongly encourage these practices during high rain events and peak periods of 6-8AM and 6-8PM until the sewer is back in service. Updates on this can be found on burlingtonvt.gov/water or on your local Front Porch Forum. 

 

STAY INFORMED 

 

We encourage the public to visit burlingtonvt.gov/water where they can review the incident response page. This page has maps, updates and FAQ’s that will help address common questions and concerns. More information on the performance of the temporary bypass project and future repair plans will also be forthcoming.  

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UPDATE 7/21 (also sent via FPF)

We want to offer an end of week update on the Temporary Sewer Bypass Project being constructed in response to the July 12th Winooski River sewer break. As a reminder, you can visit http://burlingtonvt.gov/water to find our incident response page with all material available.

There are 4 important things we want you to know about as we head into the weekend: the status of our ongoing response plans, how to conserve your wastewater, info on some temporarily blocked catch basins and how to stay informed.

***3 PART RESPONSE: REDUCE, REROUTE AND REPAIR ***

We are continuing our round-the-clock operation to pump wastewater from the broken line, and haul it to North Plant for full treatment to reduce untreated flows to the Winooski River. We are treating approximately 75% of flows to North Plant at this time.

We have made significant progress in constructing a temporary bypass pipe overland which will reroute these flows to North Plant. At this time, we are cautiously optimistic that we will have it up and running early next week. We expect this new line to handle just about 100% of flows during most circumstances.

Short and long-term repair options are still under evaluation, and we'll attempt further dye-based inspections of the broken pipe next week.

***NNE: PLEASE CONSERVE YOUR WASTEWATER***

As a reminder, we are asking residents generally on the east side of the New North End to conserve your wastewater and especially from 6-8AM and 6-8PM. Please limit – to the extent posisble – what goes down drains and toilet. As our bypass operation comes online soon, please expect further instruction on what this means for conservation efforts. You can see conservation tips and find out if the conservation request applies to you at http://burlingtonvt.gov/water.

***PROACTIVELY BLOCKED CATCH BASINS***

We have used coir mats with woven geotextile material underneath to temporarily block catch basins in the catchment area that directly impacts the broken line that runs to North Plant. This is an effort to reduce flows, and aid our pump and haul operation. You may notice increased street ponding which will only be stormwater, and not wastewater. Please do not remove this material. For an image of what this looks like, please visit our incident response page.

***STAY INFORMED***

We encourage residents to sign up for VT-Alert at http://burlingtonvt.gov/dpw. DPW uses this platform to communicate quickly about urgent situations like the July 12 sewer break, boil water notices, parking bans during winter storms and much more. You can also check our website for an ongoing response to the July 12 Winooski River sewer break.

***QUESTIONS:***

We're here to help. Please email water-resources@burlingtonvt.gov with questions (expect a reply within 1 business day). Please direct urgent questions to 802-863-4501.

UPDATE 7/19

We want to offer a midweek update on our response to the July 12 sewer break under the Winooski River. We'd also like to remind residents generally on the east side of the New North End to continue conserving wastewater (anything that goes down drains or toilets). You can find out if this request applies to you at http://burlingtonvt.gov/water.

Construction of the temporary bypass sewer pipe is underway; 24/7 pumping/hauling of wastewater is ongoing; repair plans are being evaluated. You can find updates, faq's, maps & more info on the July 12 Winooski River Sewer Break at http://burlingtonvt.gov/water.

See below, and attached, for some important questions we've been getting from #btv and Colchester residents (more FAQ's at the URL above):

**Why is there a sewer pipe under the Winooski River?**

The sewer line crosses under the Winooski River in 2 places (see map at the URL above) and was first installed in the 1950's, around the same time as when North Plant was built. This chosen path at the time allowed the most efficient, feasible route for wastewater from this area of the New North End to reach North Plant for treatment.

In the 1950's, it was probably not feasible to have a cast iron pipe directionally drilled, so this pipe is at or near the river bed surface. Modern sewer system design would likely avoid a river crossing entirely.

**Reasons for installing a river crossing:**

-It provided a direct sewer route, reducing the length of pipe needed and relies on gravity (via an inverted siphon design), rather than pumps to direct wastewater to North Plant.
-The river crossing is ~3500 feet; a forcemain along the road would need approximately one mile (5300') and require multiple private easements
-While our current temporary bypass operation is, in effect, a force main, a permanent installation would require private easements, additional controls, excavation, tankage, and potentially other things like generators.

**Why not just bury this temporary bypass pipe, and make it permanent?**

The design and construction of a new, buried sewer line over-land would require a mile long excavation, and would need to be carefully designed to avoid other utility conflicts (gas lines, water lines, etc). It would also require the above mentioned private easements, and a permanent force-main. It couldn't be built as quickly as this temporary on-ground system. This temporary bypass pipe will soon allow us to capture just about 100% of untreated flows under most circumstances.

**So, what's going to happen with the damaged pipe?**

We are moving with all deliberate speed to continue reducing any untreated flows to the Winooski River and are capturing upwards of 75% of normal flows to North Plant for treatment. At the same time, we are evaluating a range of options for the permanent fix.

Once water levels safely recede and the water is less murky, we will inspect the damage on the pipe to determine a) what short term fixes can be employed AND b) what long term repairs or designs can be implemented for a more climate resilient pipe.

**A note on inspection:**

Residents have asked how we know if this pipe is damaged. We conduct 2x/year dye testing to ensure there are no leaks and have periodic checks by a diver to inspect the condition of the pipe. The last dive inspection was actually in June 2023. We also have flow monitoring technology at the Plants which we monitor to determine if an anomaly is ever present in the amount of wastewater coming into our Plants. This is what helped us to discover the July 12th break, and then mobilize quickly.

UPDATE 7/18

We have made the decision to plug any catch basin that is connected to our combined sewer network that directly impacts the North Plant siphon break where we are currently hauling wastewater via tanker trucks. This is in an effort to focus our bypass operation on wastewater collection instead of being inundated by stormwater. You may see some increased street puddling. Please note that the puddles will be stormwater only and will not be sewage reaching the surface. Please do not remove any of the items that we are using to plug the catch basins, see attached pictures for examples of what these plugged basins look like.

PROGRESS UPDATE 7/17 (also issued via FPF)

CONSERVE: As a reminder, if you live on the east side of the New North End we are requesting that you conserve wastewater (anything that goes down drains or toilets), especially from 6-8AM and 6-8PM. See the conservation map, and all details at: https://www.burlingtonvt.gov/water/WinooskiBreakJuly12.

REROUTE: Crews mobilized on Friday and have begun construction on a temporary on-ground bypass wastewater pipe today. This temporary system will bring wastewater flows from the interceptor point on the broken line to North Plant for treatment. At that time, we expect 100% of flows in most circumstances to be able to be treated. Construction on this temporary line will last 10 or more days. See the approximate path this new line will take, along with FAQ's about the incident and the temporary pipe at the URL above. If you live along this route and we have your email address, we have sent you an email (please check spam folders). We also have signage out in the right-of-way with more to come.

REDUCE FLOWS: We are asking certain sections of the NNE to reduce wastewater flows. We're also using tankers to pump and haul wastewater from the broken line to North Plant for treatment. This has been on-going, around the clock since the end of last week. At this time, we are capturing approximately 75% of all flows to North Plant for treatment.

REPAIR: River levels are still high and the clarity of the water is still murky. This is preventing us from completing a thorough inspection of the broken pipe. We are looking at alternatives. However, this is not slowing down the bypass construction project.

STAY INFORMED: Check the URL above for updates, maps and faqs. Sign up for VT-Alert at the above URL, as well. Check http://enjoyburlington.com for public beach updates, and always be sure to follow any signage at access points. Email water-resources@burlingtonvt.gov with questions. If urgent, please call 802-863-4501.

PROGRESS UPDATE (7/14 - also issued via FPF & VTAlert)

**Progress Update: Winooski River Sewer Break & Ongoing Wastewater Conservation Request 7/14/2023**

**Removing Flows**

Starting at 3PM on July 13th, DPW Water Resources began pumping wastewater out of the affected sewer line and hauling it to North Plant for full treatment. See the blue line on the attached map for the trucking route.

The DPW truck was joined by a second truck via our contractor, BP Wastewater, beginning at 10PM. From 3PM until 6AM we were able to remove 126K gallons of wastewater for full treatment at North Plant. In effect, between the initial “quick fix,” and the pumping and hauling effort, we are now capturing around 70% of the typical flows for treatment at North Plant. Hauling efficiency will slow slightly during the day with regular traffic, but we estimate that we should be able to divert as much as 175K gallons a day with this approach.

**Re-piping a Temporary Flow Path**

This pumping and hauling effort will now be going on around the clock until we construct a temporary on-street piping bypass network from the affected sewer line directly to North Plant. Mobilization for this temporary bypass effort is now underway through the affected corridor – shown via dotted line in the attached map (this alignment may change). Over the next few days, trucks will be showing up to the corridor; pipes, fittings and other equipment will be delivered and work will begin to construct a temporary above-ground pipe network to bring these flows to North Plant. Properties along the corridor will be receiving additional information and details later today.

**Repairing the Break**

As these efforts continue on, and as Winooski River levels recede, we are working on repair plans to the current broken pipe to restore flows.

For more background on the sewer break, the immediate mobilization by Water Resources staff and next steps, please visit https://www.burlingtonvt.gov/water/WinooskiBreakJuly12.

As a reminder, we are requesting that a specific subset of New North End addresses work to conserve their wastewater (in effect reducing what goes down drains and toilets) until the bypass network is constructed and activated. See the URL above or the map below.

INITIAL SUMMARY & UPDATE (posted 7/13)

What Happened? Around 6AM on July 12, Burlington Department of Public Works (DPW) Water Resources staff discovered that there was a break in a wastewater pipe that crosses underneath the Winooski River which brings untreated wastewater into North Plant. Crews were quickly mobilized to respond.

 

What Caused This Break?  This pipe undergoes biannual inspections and the last inspection was actually in June 2023. This break is very likely a result of the intense and powerful storm flows currently affecting the Winooski River. With rapid water flows, we expect there was heavy scouring, leading to erosion around the pipe which led to this breakage. 

What's Being Done to Fix This?

• By 8:45AM on the morning of the break, Water Resources staff was able to cap the sewer main at the Plant to limit untreated wastewater flows into the River. This has helped us capture 50% of the normal flows to the plant. The remaining untreated flows represent approximately 10% of the City's wastewater.

• We are quickly working on a multi-pronged approach and evaluating the feasibility of quick, effective solutions along with a longer term repair plan. More details on the repair plan to come. It will entail:

  • Removing untreated flows to the river
  • Repiping to get these flows through the Plant
  • Repairing the pipe: First, temporarily to bring flows back through and then permanently to ensure more resilient infrastructure

What Can the Public Do?

• Conserve water/waste from entering the wastewater system if you reside in the New North End Collection & Treatment area. See conservation link above
• Pay attention to all signage and instructions from local officials. At this time, the North Lake Access Areas in Burlington within 1 mile of this incident are closed to swimming. We are aware that Colchester has signed certain access areas, as well. Burlington's Access Areas will remain closed up to 48 hours after the untreated flows stop. 
• Check enjoyburlington.com for further information on Burlington's public beaches - which are tested for bacteria regularly. 
• Sign up for VT-Alert at burlingtonvt.gov/btv-alerts.