Mill Creek trunk rehabilitation

The Mill Creek combined sewer trunks carry wastewater from a large part of south Edmonton towards the Gold Bar Wastewater Treatment Plant, and also convey rainwater and snowmelt from some of Edmonton’s older south side neighborhoods. This line services approximately 58,000 sanitary connections in south Edmonton. Segments of the combined sewer trunk have been observed to be in very poor condition.

Inspections have identified that the existing tunnel running through the Ritchie and Old Strathcona neighborhoods, as well as under the Mill Creek Ravine, requires replacement to ensure it continues to reliably meet the needs for south Edmonton.

The project is expected to begin in mid-March 2023 with completion in 2026.

Project overview

The Mill Creek combined trunks carry wastewater from a large part of south Edmonton towards the Gold Bar Wastewater Treatment Plant, and also convey stormwater and snowmelt from some of Edmonton’s older south side neighbourhoods. This line services approximately 58,000 sanitary connections in south Edmonton.

The Mill Creek combined trunk services the Edmonton region highlighted on the map.

In 2020, crews had identified large holes in the trunk as well as a deteriorated manhole. An emergency repair was completed in Mill Creek Ravine, which involved impacts to the trail system, tree removal and heavy equipment being transported and utilized on site.

Further inspections were completed to evaluate the remainder of the trunk’s condition. Due to the poor condition and location of the line, a new trunk was needed to replace the existing trunk and ensure the system continues to reliably meet the needs of the City of Edmonton. Once the new trunk has been constructed, a portion of the existing trunk in Mill Creek Ravine will be abandoned.

The selected alignment of the new trunk is located outside of Mill Creek Ravine. The completion of the new trunk will help reduce the risk of significant environmental impacts to the ravine in the event of a trunk failure.

Timelines

This project will be completed in 3 stages; work is anticipated to being in January 2023 on Stage 1 and we estimate the entire project will be finished by Spring 2026.

Please note that these timelines are estimates and are pending approvals, material procurement/availability, construction conditions and weather.

Stage one construction

Mid-March 2023 to mid-2025

Stage One of the project will require significant closures to both the recreation field at Mill Creek School (Worksite#1), as well as the greenspace in Tubby Bateman Park (Worksite #2). The alignment of the trunk was selected in order to connect to existing combined trunks along 80 Avenue and 88 Avenue, as well as reduce the risk of impacting MillCreek Ravine.

During Stage One of the project, crews will construct a 30 metre deep shaft s for the tunnel boring machine (TBM), which will be used for the construction of the new tunnel. Two shafts will be constructed for the tunnel boring machine: an entry shaft at Mill Creek School, and a retrieval shaft in Tubby Bateman Park.

Construction of the entry and retrieval shaft is anticipated to take eight months to complete. Once the shaft s havebeen completed, tunneling will begin. The majority of the activity will take place at the entry shaft; the retrieval shaft site will be inactive for approximately one month after the retrieval shaft has been completed.

The TBM will be lowered into the entry shaft and will travel north underground along 97 Street until it reaches the retrieval shaft. Underground 24/7 tunneling is expected to take place for approximately 150 consecutive days. A slurry separation machine, located at Worksite #1 near Mill Creek School, will also operate 24/7 during tunneling activities. Once the tunneling stage is complete, it will take approximately four months to convert the shafts to manholes, providing access into the tunnel for future maintenance.

Full restoration will follow and is anticipated that the school field and park will reopen in mid-2025. Once the new trunk is completed, Stage Two work will begin in order to connect existing sewer connections on 80 Avenue, between 97 Street and 96 Street, to the new trunk.

Mid-March to summer 2025

Sidewalks/walkways

Pedestrians will be detoured along the west side of the construction site via a temporary walkway.

Working hours

Typical hours of work will be from 7:00 a.m. to 7:00 p.m., Monday to Saturday. If required, these hours may be extended, and construction may occur on Sundays from 9:00 a.m. to 5:00 p.m. During tunneling, the tunnel boring machine will be running 24/7.

Haul route

Two haul routes from the site may be utilized in order to avoid traveling on 98 Street in front of Mill Creek School. For the main haul route, trucks will proceed north on 96 Street to 82 Avenue. In the event that this route cannot be accessed, trucks will proceed south toward 63 Avenue.

While the haul route will see increased activity due to construction, the routes will remain open to regular traffic. There may be intermittent road closures near the worksite while crews are moving equipment and materials.

Due to the proximity to Mill Creek School, no tandem trucks will travel to and from site on weekdays during school drop-off (between 8:00 a.m. 9:00 a.m.), or school pick-up (2:45 p.m. and 3:45 p.m., including Thursday early dismissal from 1:45 p.m. to 2:45 p.m.).

School soccer field

The soccer field goal posts will be moved further west to accommodate the site’s laydown area and allow for the continued use of the soccer field. The site will also be fenced and will use site hoarding material to block visibility and deter activity around the site.

Once construction is complete, the soccer goal posts will be moved back to their original location.

Tree trimming, removal and replacement

Several trees along the fence line on the west side of 97 Street, between 79 Avenue and 80 Avenue next to Mill Creek School, have been removed.

Once construction is complete, the City of Edmonton Urban Forestry department will determine the number of trees to be replaced and the replacement locations.

Spring 2023 to mid-2025

Traffic

There will be no parking adjacent to the worksite on 97 Street.

Sidewalks/walkways

Pedestrians will be detoured via a temporary sidewalk from the east side of the worksite to the pedestrian path on the north side of the worksite (connected to the parking lot).

Working hours

Typical hours of work will be from 7:00 a.m. to 7:00 p.m., Monday to Saturday. If required, these hours may be extended, and construction may occur on Sundays from 9:00 a.m. to 5:00 p.m.

Haul route

One haul route will be used to access this site. Trucks will proceed south from the worksite along 97 Street to 82 Avenue. There may be intermittent road closures on 97 Street near the worksite while crews are moving equipment and materials.

Tree trimming, removal and replacement

Several trees in the north east corner of Tubby Bateman Park on 97 Street will be removed. Once construction is complete, the City of Edmonton Urban Forestry department will determine the number of trees to be replaced and the replacement locations.

Tubby Bateman Park green space

The worksite for the construction of the retrieval shaft will encompass a large portion of the green space within Tubby Bateman Park.

The playground will remain open during construction, however a large portion of the park space will be closed to the public for the duration of the Stage One construction.

We are working with the City of Edmonton to relocate or store any historic resources that are currently within the work area.

Stage two construction

Spring 2025 to fall 2025

Crews will perform open-trench work along 80 Avenue, between 96 Street and 97 Street, in order to connect the existing sewer to the new trunk. A full road closure is required to accommodate excavation of the work area. The road will remain closed for the duration of the Stage Two work. Please note, further notification will be provided to impacted residents before Stage Two work begins and will include details of traffic impacts, timelines and schedule when possible.

Community disruption

EPCOR will work with residents to understand individual impacts related to this work, such as garbage pick-up, accessibility issues and other needs. We will work to determine mitigations on a case by case basis.

Traffic

There will be a full road closure on 80 Avenue, from 97 Street to the intersection of 96 Street, to accommodate open cut construction. The road will be closed for the duration of this work.

Sidewalks/walkways

Sidewalks on 80 Avenue will remain open for pedestrians. Working Hours Typical hours of work will be from 7:00 a.m. to 7:00 p.m., Monday to Saturday. If required, these hours may be extended, and construction may occur on Sundays from 9:00 a.m. to 5:00 p.m.

Haul route

Trucks will proceed north on 97 Street to 82 Avenue or south toward 63 Avenue.

Stage three construction

Summer 2025 to spring 2026

During stage three, crews will decommission the existing trunk line within the ravine by filling it with a concrete-like material. Crews will use the existing trails as an access route to complete this work, however it is anticipated that trails remain open to pedestrians the majority of the time.

Community disruption

There may be intermittent trail closures while crews are moving equipment, such as a mini-excavator, and materials to the worksites.

Please note, further notification will be provided to impacted residents before Stage Three work begins and will include details of traffic impacts, timelines and schedule when possible.

What to expect during construction

To try to understand and reduce the construction impacts to the public, we've met with Mill Creek School, Bonnie Doon Community League and several other organizations that will be impacted by the work. EPCOR has also provided a project backgrounder to impacted residents of Old Strathcona, Ritchie, King Edward Park, and Bonnie Doon communities.

Noise abatement measures will be utilized at the 24 hour a day tunneling sites; however, construction noise should be anticipated. Activity is reduced to the minimum requirement during overnight hours.

Detours will be created for any sidewalk/pedestrian crossing closures.

Lighting structures will be place low within the worksite to minimize light from spilling outside the worksite.

As the construction worksites are in close proximity to Mill Creek School and Tubby Bateman Park, the site will utilize secure fencing and site hoarding material to block visibility and deter activity around the site.

EPCOR will work with Mill Creek School to provide safety education for students to promote safe behaviour around construction sites.

EPCOR will also provide information to the school to provide to parents.

Tunnel Boring Machine

We'll be using a Tunnel Boring Machine (TBM) at during this project. The tunneling process occurs underground using a tunnel boring machine (TBM); however, shafts are required at the start and end points.

During tunneling, it may appear not much work is occurring; however, this is being done underground.

A machine used to excavate tunnels by breaking the surrounding soil/earth/rock to create a large diameter tunnel.

The TBM being used for this project is 4.5 metres in length, weighs approximately 30 tonnes and is 2.7 metres in diameter.

It is anticipated that the TBM will progress, on average, at a speed of about six metres per day in the expected conditions.

The TBM operates under a pressure system to move forward. This is facilitated by the use of a slurry (water and material mixture) to lubricate the pipes and reduce the friction.

When tunneling stops, the slurry may harden and cause the pipes and TBM to be unable to be pushed forward.

A slurry separation machine is a large piece of equipment (approximately two stories tall) used to manage soil removal. The machine separates the solids from slurry, so that the water can be recycled back to system. The machine operates 24 hours a day while the TBM is tunneling.

Noise abatement panels will be used to dampen the noise generated by the machine.

Causes of possible schedule delays

While we always do our best to plan construction and abide by construction timelines communicated to the public, unexpected events can potentially occur which may delay the schedule.

Geotechnical investigations have been completed along the alignment and we anticipate that the ground conditions are favourable for tunneling. However, there is a risk the TBM could encounter harder soil or boulders, which could slow down progress.

Extreme weather including severe cold, heavy rains, high winds and lighting make working unsafe. During these conditions, the site will be shut down.

The start date of the project is dependent on relocation of the utilities, including a water main at Tubby Bateman Park, as well electricity and telecommunication lines at Ritchie School. Electricity and telecommunication line relocations are anticipated to take place in Q1 of 2023. The watermain relocation is anticipated to take place in Spring 2023. There may be some disruption to local services, however more information will be provided at the time of construction.

The TBM will be delivered from overseas, either from the manufacturer or from another project site. If there are delays with shipping, the tunneling portion of the project may be delayed.

Questions?

Your questions are important to us.

Contact EPCOR

Phone: 780-412-4200
Email: epcorprojects@epcor.com

Mill Creek trunk rehabilitation

Project overview

Timelines

Stage one construction

Stage two construction

Stage three construction

​What to expect during construction

Tunnel Boring Machine

​Causes of ​​possible schedule delays

What to expect during construction

Causes of possible schedule delays