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Ward 1 News: Geotechnical Drilling in Bow River

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Bowness Sanitary Offload Trunk Project Update

A part of the Bowness Sanitary Offload Trunk Project includes geotechnical drilling. Testing is required as part of the preliminary work for the detailed planning of the Bowness Sanitary Offload Trunk Project.

Testing soil conditions will take place on June 2nd in Shouldice Park (west end of the park just south of the 16 AV overpass) and June 3rd near 67 St and Bow Crescent NW. Work will take place between 8:30 a.m. and 7 p.m.

Residents will observe trucks in the vicinity of the test area and hear some noise as the work occurs. Efforts will be made to minimize the impact on traffic flow.
Residents near the 67 ST and Bow Crescent NW site received hand delivered customer notices advising them of the work.  The information was also sent to Montgomery and Bowness Community Associations.

Information about the project is available at or by calling 3-1-1



The City of Calgary is addressing the existing constraints in the Bowness sanitary trunk by constructing an offload trunk using trenchless microtunnelling technology. The project includes:

a) Approximately 1900 metres of 1650 millimetre main trunk installation;
b) Approximately 200 metres of river crossing using twin 900 millimetre pipes.

Calgary’s northwest communities are approaching sanitary capacity and the project will better accommodate wet weather flows and meet the future wastewater loads. Tests will be conducted May 1-2, 2014. Information about the Bowness sanitary trunk is available at The City of Calgary website and through  3-1-1.

Project Details

As part of the detailed design process The City is conducting geotechnical investigation inside the river to finalize the profile of crossing the Bow River using micro tunneling construction method. This method of construction will minimize and/or avoid environmental impacts to the Bow River, and also avoid several areas of urban congestion. To support the detailed design, drilling in the river and ground penetrating radar mapping of the Bow River will be undertaken along a section of the proposed trunk May 1-2, 2014. The project requires Historical Resources Impact Assessments approval from Alberta Culture. The process of acquiring the approval requires filing the results of archelogical testing in specified locations.

Q&A: What is happening in the Shouldice dog park?

Calgary Parks has given permission for archeological test pits to be dug in three locations adjacent to the Bow River on May 1 and May 2, 2014. The archeological testing is part of the required preliminary work for the Bowness Sanitary Offload Trunk Project. A backhoe will be used to dig the two pits in the off leash area near Shouldice Park and one pit across the river from the Park, south of the TransCanada Highway. The purpose of the pits is to examine the soils for historical artifacts. A palenotological resource will be present during the digging. The contractor will clean up and restore the damaged area after the required testing is complete.

Q&A: What is happening in the Bow River?

Geotechnical investigation of the soil conditions under the channel of the Bow River will be conducted on May 1-2, 2014. The investigation involves drilling one borehole in the channel of the Bow River adjacent to Shouldice Park, south of the TransCanada Highway. Mapping of ground rock formation under the river is scheduled for April 28, 2014, using ground penetrating radar from a jet boat.

Q&A: Why is testing required?
• A portion of the Offload Trunk will be placed below the bed of the Bow River.
• Testing is part of the required detailed design work for better understanding of the soil condition beneath the Bow River.
• The geotechnical investigation is critical in determining the appropriate depth for safely crossing the river.

Q&A: Who approves the testing?

• Alberta Environment approved the geotechnical investigation in the Bow River.
• Baseline fish and fish habitat data and recommendations from a Qualified Aquatic Environment Specialist (QAES) were undertaken to fulfill the regulatory requirements under the provincial Water Act and the federal Fisheries Act.
• Once detailed designs have been finalized, a separate Water Act application will be sent for approval for the proposed construction of the Project.

Q&A: How is it done? 

The detailed process is as follows:

• A track driven carrier and drill will be used to complete the geotechnical investigation.
• The carrier will enter the river channel via the east bank and will not drive into areas of the river where water is greater than six feet deep.
• The contractor will limit the disturbance by placing enviro filter cloth and drive the drill rig on the filter cloth.
• It is anticipated that no vegetation clearing or grading will be required for access.
• The drill will be transported into the river on the track driven carrier.
• The contractor will keep the movement of the machinery within the Bow River to an absolute minimum to avoid unnecessary disturbance to fish and fish habitat.
• Boreholes will be 115 mm in diameter and will reach 30 metres below the riverbed.
• The test hole will be sealed with a combination of clay, cement, and cement-bentonite grout plugs to prevent water flow. The casing will remain below the gravel substrate until the cement has been cured, upon which the casing will be lifted, allowing the riverbed gravel to fill the void naturally.

Q&A: What will be done to protect the environment and the fish?

• Precautions to protect the environment including fish habitat, water quality and adjacent lands will be strongly adhered to during the geotechnical investigation.
• The proposed geotechnical drilling activities are not anticipated to cause ‘serious harm’ to fish resulting from permanent alteration or destruction of fish habitat, or death of fish, as per the definitions provided in the Fisheries Protection Policy.
• An AECOM crew will be responsible for water quality sampling, analysis, and reporting.

The Water Quality Monitoring Plan includes proposed sampling methods, safety, threshold criteria for total suspended solids, turbidity, and pH, and the response plan that will be implemented during geotechnical activities.

Water quality protection includes:

• Washing the drill rig thoroughly.
• Using environmentally friendly hydraulic fluid.
• The test holes will be drilled using casing between the working platform on the water surface and the river bed to minimize the risk of sediment release in the water.
• No water withdrawals from the Bow River will be required, as the contractor will provide their own containerized drilling fluid upon arrival to the site.
• Water will be used as a drilling fluid (if required) to conduct the proposed geotechnical work. The drilling fluid will be circulated in a tank adjacent to the equipment on surface. Any sediment-laden water will be collected and disposed of away from surface water bodies or adequately filtered prior to release.
• The drill cuttings will be contained and brought to surface for proper disposal, and will not be discharged into the river.
• The proposed geotechnical drilling activities are not anticipated to result in heavy sedimentation.

This content represents the personal views and opinions of the Councillor and should not be taken as a statement of policy of The City of Calgary. The inclusion of any external content does not imply endorsement by The City of Calgary.

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