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Project Background

In 2012, storms caused extensive surface flooding, damaged homes, vehicles and property and caused sewage backup into basements throughout Tweddle Place. This neighbourhood was identified as a high priority for drainage upgrades under the City’s Expanded Neighbourhood Flood Mitigation Program. The upgrades in Tweddle Place will provide the community with a 1:100 year level of flood protection that is consistent with standards in newly developed neighbourhoods.

Upgrades planned for Tweddle Place include a number of storm sewer upgrades, sanitary storage pipes, construction of drainage swales to relieve stormwater trapped in sag areas and expansion of the existing dry pond along 91 Street.

Construction of the project is staged over seven years. Open excavation construction methods will typically be used. As upgraded pipes are very large, residents can expect that the full width of the roadway will be cut open in some areas. During construction, residents will temporarily lose access to their driveways and street parking, and areas adjacent to construction zones may be more congested as street parking shifts to these areas.

Project Update - February 2017

Millbourne Flood Mitigation Task Force Meeting Minutes #10

Millbourne Flood Mitigation Task Force Monthly Reports

April

March

Project Related Questions

Why are sewer upgrades required?

In 2012, storms caused extensive flooding, damaged homes, vehicles, and property and caused sewage to back into basements throughout Tweddle Place. The neighbourhood has also previously experienced flooding during large rain events. It was identified as a high priority for drainage upgrades under the City’s Expanded Neighbourhood Flood Mitigation Program. The upgrades in Tweddle Place will provide the community with a level of flood protection that is consistent with standards in newly developed neighbourhoods.

How long will this project take?

Community consultation and engineering studies began soon after the 2012 flooding, with detailed design beginning in early 2014. Construction of the project is staged over seven years beginning in 2015. The construction timing is based on available budget for this work, scope that can be completed in one season, priority of upgrades, and impacts to the neighbourhood (road closures, pedestrian accommodation, utilities coordination).

How will this work be communicated with me?

Design Stage: The City has engaged with residents throughout the design stage. This included public open houses and information meetings, project information mail outs, updates to the community league and North Millbourne Flood Mitigation Task Force, surveys/questionnaires, updates in community league newsletters and door to door visits. These provided opportunities for residents to give their feedback about the proposed upgrades, and the comments were considered in developing the final design.

Construction Stage: During the construction stage, an update of the construction status and planned work for the next season is typically mailed out each fall. Residents are notified of upcoming construction in their area one to two months prior to construction beginning through mailouts and door to door visits, and a pre-construction open house held at least two weeks prior to the start of construction each year. Residents affected directly by the construction have an opportunity to ask construction specific questions to the contractor at these events. Prior to the construction, a construction notice is delivered to the community. Residents should keep this notice handy, as it contains key contact information should residents have any concerns or questions. Periodic updates about the construction progress will be distributed to directly affected residents. Updates to the community league and North Millbourne Flood Mitigation Task Force are also provided.

Design Related Questions

What upgrades are planned?

Upgrades planned for Tweddle Place include a number of storm sewer upgrades, sanitary storage pipes, construction of drainage swales to relieve stormwater trapped in low areas and expansion of the existing dry pond along 91 Street. The sewers will take stormwater flows to the downstream sewer system and eventually out to the river. When capacity is not available in the downstream system, the stormwater will be temporarily stored in the dry pond. The City has purchased two residential lots in low lying areas of the community. These lots will be converted to drainage swales that will route stormwater on the ground into the 91 Street dry pond. Since catch basins can become obstructed with leaves and other debris, and pipes can fill up, the surface drainage swales through the two empty lots will provide an alternate flow path for stormwater unable to enter the pipe system.

How does the pond work?

During normal operation, water in Tweddle Place stormwater pipes flow downstream into the Mill Woods Double Barrel pipe system and the pond will remain dry. During large storms, pipes in the community and downstream sewers can fill up. When the pipe system is full, water will back up into the Tweddle Place dry pond. In addition, the dry pond will collect surface stormwater directed overland into the pond. The dry pond will store any collected stormwater until capacity is available in the downstream system. When capacity becomes available, the stormwater will drain through catch basins in the bottom of the dry pond into the pipe system. As the name indicates, the dry pond will be dry the vast majority of the time.

Why does the berm have to be removed?

The berm is being removed to enable expansion of the dry pond. Additional stormwater storage volume is required to hold the flows that will be directed to the pond. In addition, removal of the berm ensures that low areas in the community have an unrestricted flow path into the dry pond across the drainage swales that are being constructed.

Why do the trees have to be removed?

Regretfully, trees along the berm have to be removed to allow the berm to be removed. Trees that would be impacted by construction activities will also be removed, This area will be re-landscaped at the end of the dry pond expansion with a mix of native grasses and vegetation, trees and shrubs. Seating areas will also be incorporated into the expanded dry pond, and the existing shared use path will be relocated further east in the pond area. Access to the shared use path will be maintained with openings along the future sound barrier, a living wall.

What is a living wall?

A living wall is a visual and sound barrier that incorporates plant material to form a hedge-like, more natural alternative to traditional sound barriers. It replaces the sound and visual barrier functions of the existing earth berm. A demonstration project of the living wall was built in late 2014 near the Mill Woods Christian School along 91 Street.

The living wall demonstration project seems to be struggling. Why is this, and what is being done to ensure it grows?

The living wall demonstration project was constructed in fall 2014. The intention of the demonstration project was to allow the community to experience this type of wall and to confirm its ability to grow in Edmonton’s climate. In a survey, the majority of people who experienced the wall indicated they were supportive of making it a permanent replacement for the berm. Testing proved it was effective as a noise barrier.

For the demonstration, a temporary water supply was installed to help the wall get established. In the establishment phase of the wall, it is critical for the vegetation of the wall to be well irrigated. In the spring of 2015, someone had shut off the water supply, depriving the wall of water during a hot, dry spring. This resulted in the death of many of the willow stalks. While some additional willow stalks were planted to compensate for these deaths on the community side of the wall, a large number of willows were not replaced.

During the dry pond expansion, this section of the wall will be augmented with additional plants. In addition, the full installation will include a piped source of water for the wall. To ensure proper establishment, the contractor will be required to maintain the wall for an extended period.

Will the living wall prevent noise from Whitemud Drive and 91 Street?

The living wall is a sound barrier, and the effectiveness of its design has been proven with noise monitoring and modelling according to engineering best practices. The wall contains a soil core that is a barrier to sound and functions year round. It also provides other environmental benefits such as cleaning the air, promoting biodiversity and providing wildlife habitat.

Construction Related Questions

How will construction affect access to my home?

During construction, residents in some areas will lose access to their driveways and street parking, and areas adjacent to construction zones may be more congested as street parking shifts to these areas. The project team works to limit the duration of closures, but wet weather can significantly impact the construction schedule, access and site conditions. Residents with special mobility concerns can contact the project manager to discuss accommodation during construction.

How will construction affect my property?

Portion of yard along roadway may be removed: The road right of way typically extends into front yards, sometimes as much as five metres. Utilities and services such as cable are located within this right of way. These utilities sometimes have to be exposed for construction work. In cases where large or multiple pipes are being constructed and located deeper in the ground, the excavated trench may need to extend close to a resident’s property line to maintain a safe excavation. The contractor is required to restore any impacted landscaping to pre-construction conditions.

Tree removal: Where construction affects the root zone of private trees, the City may approach property owners to remove the affected trees. The City does this to avoid burdening owners with long term maintenance issues, because construction impacted roots may cause the tree to weaken and in some cases, die. The City will obtain permission from owners prior to removing any trees. Removed trees will be replaced.

Will contractors be storing materials on my property?

Materials storage on road right of way: Construction contractors will store pipes, materials for filling in the trench and other equipment or supplies necessary for this work along the roadway around the construction site. When spaces are available to store this material off the roadway, they will make use of these spaces. Contractors try to limit the amount of material stored on the roadways, and amounts may vary depending on how quickly the contractor is advancing construction, ground conditions encountered, supplier availability, etc.

Materials storage on private property: Contractors should not be storing materials on or using private property without permission from the property owner. Any concerns related to inappropriate storage of material or use of private property should be directed to the City’s project manager or directly to the construction contractor’s site representative.

Will I experience any disruptions to my services?

Utilities may need to be disconnected, relocated or temporarily shut down to allow construction to proceed safely or to avoid damage to the utility. The project team will arrange for temporary supply of any affected services. There may be short duration outages associated with connecting the property to these temporary services. The contractor or utility company will notify homeowners of any planned outages at least 24 hours prior to the planned outage.

Will there be future Open Houses?

Yes, an open house will be held prior to each stage of construction. An invitation to attend the information meeting will be mailed out to the community approximately two weeks prior to the date of the open house.

What if the construction damages my property?

Occasionally, damage to property or persons may be caused by construction activities. If you believe that you have sustained damage due to negligence by the City or its contractors, you can submit a claim to the City.

For the Tweddle Place project, in areas where full road widths will be excavated, the City will offer residents pre-construction building assessments. These assessments will gather photo documentation of the property condition (interior and exterior) prior to construction. Following construction, residents who feel they have sustained damage may elect to have a post-construction assessment conducted. These assessments will facilitate resolution of any damage claims. Both assessments will be free of charge to residents.

Why is the excavation so wide in some areas?

As upgraded pipes are very large in some areas, the full width of the road right of way, from property line to property line, may be cut open to maintain safe working conditions.

What should I do if road conditions in the construction area are poor?

Wet weather can create muddy and messy conditions at construction sites. The project team and contractor work to keep roadways and sidewalks as clean and safe as possible. However, if you have concerns, please call the City or contractor contacts provided on your construction notice. The City will work with the contractor to improve the site conditions in these situations.

What should I do if service is lost during construction?

If you experience an unplanned loss of service related to:

  • Water: Contact Epcor Water’s trouble line at 780-412-6800
  • Power: Contact Epcor Power at 780-412-4500
  • Telus: Contact Telus at 1-888-811-2323
  • Shaw: Contact Shaw Cable at 1-888-472-2222

For all other concerns, contact the City project manager or the contractor contact listed on your construction notice.

For More Information

Utilities Infrastructure

Telephone

311 

Email drainageprojects@edmonton.ca

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