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​The same sequence of work activities are followed like the other sanitary trunk sewer work underway across Edmonton, these include: (1) Stabilizing the situation (ensure safety, reduce risks), (2) Assessing the issue (info gathering/inspections, and assessment) (3) Engineering Design and (4) Construction.

 

Project updates

100 Avenue trunk sewer repair

  • Hand tunnel excavation and pipe installation on 100 Avenue bypass tunnel is complete. Crew are working in the 12ft shaft on 100 Avenue to complete the manhole structure to the ground surface
  • Rehabilitation of the existing 1950mm sewer will begin once the flow is diverted to the new bypass tunnel
  • Current odour mitigation measures include using the air scrubber at 153 Street as well as covering the shaft when not in use by workers

Traffic accommodations:

Concrete trucks will temporarily block the pedestrian crosswalk at 100 Avenue as the 12ft shaft is backfilled. Crew on site will be able to assist and guide pedestrians around the trucks as necessary. 100 Avenue will remain accessible to vehicular traffic.

Schedule:

This work is expected to last for about 2 to 3 hours at a time on Tuesday August 8 and Wednesday August 9.

New bypass tunnel on 151 street between 99 avenue and 100 avenue

Pipe installation:

Approximately 10m of pipe remains to be installed from the tee connection at 99 Avenue back to the intermediate shaft between 99 Avenue and 100 Avenue. On Tuesday August 8, the crew plans to install the final pieces of pipe. This requires the removal of the plug covering the drop connection to the existing sewer.

There may be some odour experienced nearby for the period during which the plug is removed and the final piece of pipe is connected.

100 Avenue pump station

Work for the removal of the pump station was started on January 23, 2017.

A third crew on site was mobilized on July 24 to resume decommissioning of the pump station; however, with the recent rainfalls, sewage flow into the pump station was discovered, which does not permit worker entry to safely complete the manhole construction.

The crew is currently working with the drainage operations team to divert the flows back to the existing trunk sewer so work on the construction of the manhole can resume.

Progress of overall construction can be found on the August 4 update.

Odour mitigation

The air scrubber plays a major role in odour mitigation for the 100 Avenue shaft repair. In addition, there are also chemical injections (hydrogen peroxide injections and nitrate injections), into sewers of nearby pump stations. Hydrogen peroxide and nitrate will reduce the effects of hydrogen sulphide, a chemical created in sewer systems. This will help reduce odours and make the environment safer for our workers.

Overview
​A 1.5 meter diameter sanitary trunk sewer along 151 Street from 100 Avenue to 99 Avenue has been identified as having poor structural condition and requires immediate rehabilitation. Most of the work for this project is completed underground, but several shafts are required to access the sewer line.
  • The sanitary trunk sewer along 151 Street from 100 Avenue to 99 Avenue requires immediate rehabilitation given its poor structural condition.
  • 2 shafts are required along 151 Street from 100 Avenue to 99 Avenue to access the deep trunk for rehabilitation. The shaft at 99 Avenue was completed in 2015. The rehabilitation work will be completed underground through these 2 shafts.
  • A sewage bypass pipe will be installed along 151 Street from 100 Avenue to 99 Avenue.

 

What is involved with this project?

Phase One

The project consists of the installation of 2 shafts that connect the existing sanitary sewer system to the deep tunnels that run along 151 Street. The shaft will be installed at the intersection of 151 Street and 99 Avenue and a shaft north of 100 Avenue at 151 Street. The rehabilitation work will be completed underground through these 2 shafts.

Roadways and any other areas that are disturbed by the construction will be restored to their initial condition at the completion of the projects.

During construction, the intersection of 151 Street and 99 Avenue will be closed and only local traffic access allowed. North of 100 Avenue, 151 Street will be closed to traffic. During non-rush hour traffic, there will be minor disruptions to east-west bound traffic at the intersection of 100 Avenue and 151 Street. The aim is to minimize traffic disruptions as much as possible.

Phase Two

Several condition assessments are being completed for sanitary trunk sewers in the area of 151 Street and 99 Avenue. The assessment of the trunk sewer along 99 Avenue from 151 Street to 142 Street has now been completed and the first 50 m (165 ft) has been identified to be in critical condition. The trunk sewer is a critical piece of infrastructure as it services a large portion of west Edmonton, and this sewer will need to be rehabilitated.

While the design for the rehabilitation of the 99 Avenue trunk sewer proceeds, a bypass tunnel will be constructed (as a precautionary measure) to allow flow to bypass the portion of the existing trunk sewer that is in the worst condition. This new tunnel will also help with Phase one construction by allowing work to continue if it rains, and it will form a part of the ultimate rehabilitation solution of the existing sewer.

The bypass tunnel will require a second shaft about 50 m (165 ft.) east of the current work site at 151 Street and 99 Avenue.

H2S & Carbon Monoxide Monitoring

​Hydrogen sulfide (H2S) and carbon monoxide (CO) live stream monitoring

Real-time ambient H2S and carbon monoxide (CO) monitors are in place at the southwest corner of 99 Avenue and 151 Street. These monitors will show H2S and CO levels as they occur at the site in real time. Please note the sensor readings are affected by temperature, humidity, air pressure and wind speed and may affect the accuracy of the readings. The sensors can measure H2S and CO levels to an accuracy of +/- 0.5 parts per million, and they will be adjusted once every 6 months.

All monitoring data, real time and other ambient monitors, will continue to be provided to Alberta Health Services.

The real-time ambient air monitor live stream is online and publicly available. A bin has been placed over the unit to cover it from weather and reduce reflections from the glass. The bin still allows air flow to the sensors and gives a great view. LED lights have also been added inside of the bin so the monitor can also be viewed online, at night.

City-Wide Sewer Gas Composition Study

A summary of work done for Edmonton was completed in Spring 2016 and a brief overview of the findings have been provided for the public. Given the concerns and questions that residents have frequently raised  regarding odour and health, and the length of time that the sewer rehabilitation project has been going on in this community, West Jasper Place (WJP) was selected as 1 of the 3 sites where sewer gases were sampled. 

Open house

​On May 9, 2017, an open house was held for the West Jasper Place/Sherwood community sewer rehabilitation work. The session included a presentation which provided project information and progress.

Odour control

​Bioxide

Bioxide, a non-toxic chemical way to prevent hydrogen sulphide from forming, will be continuously injected into the system. After working hours, the shafts will be covered to minimize any odours.

Mobile carbon filters (air scrubbers)

The shaft at 151 Street and 99 Avenue is still capped. Before the cap will be removed, 2 larger capacity air scrubbers will be placed at the intersections of 151 Street and 99 Avenue, and 151 Street and 100 Avenue:

  • Air scrubber 1 — 13.4 m (44 feet) long X 6 m (20 feet) wide*
  • Air scrubber 2 — 9.3 m (31 feet) long X 3 m (10 feet) wide

*The dimensions for air scrubber 1 are different from when first communicated as it can be put together differently due to the modular design of the unit. The configuration being used is smaller than the one the manufacturer sent.

The gentleman in the following photos is 5'8" (1.77 m) for reference.

 

Scrubber tank (there are three) for air scrubber 1

 

Filter for air scrubber 1

 

Manifold for air scrubber 1

 

Air scrubber 2 (the whole unit) 

Liquid treatment of waste water with chemical injections at pumping stations

As an added measure of odour mitigation, and to ensure worker safety, chemical treatment of waste water will be used to reduce the amount of hydrogen sulfide in the waste water. The rate of chemical injections can be adjusted to meet changes in the condition of the waste water and the air scrubbers’ performance.