West Quesnel Land Stability

The Uplands area of West Quesnel is experiencing impacts from ongoing ground movement. This movement has been occurring over a long period and is very slow, between 13 - 84 mm per year. The effects on buildings and civic infrastructure vary with location but can be significant.

Background

A large, ancient landslide underlies a significant part of West Quesnel. Land movement in the West Quesnel Land Stability Study Area has been occurring over a long period. This movement is linked to annual precipitation and snowmelt conditions. The impacts on buildings and infrastructure are significant.

The area is an attractive, established residential community, including 940 parcels of land, 750 homes, an elementary school and several businesses. The total value of the land, improvements, services and infrastructure in the study area exceeds $100 million; the area is important to the economic and social viability of the City of Quesnel and is home to more than 20% of the City’s population.

Latest findings and results

Multiple studies have confirmed that West Quesnel sits on a large, ancient, slowly moving landslide. Since 2018, our full system of pumps and drains has been removing water from the ground. The groundwater and movement in this area was gradually reducing. However, in recent years of significant rain and snowfall, the ground movement has significantly increased again.

In 2020, our system measured an average of 84 mm of ground movement compared to an average ground movement of 13 mm in the years 2013 to 2019 .In 2020 123 million litres of water was removed by the pumping wells which is the most since the inception of the program. An additional 74 million litres were removed by the horizontal drains. This significant jump in groundwater and ground movement is linked to the high rainfall and snowfall amounts in 2019.

The last public meeting was on Thursday, June 2 at Voyageur Secondary School. Watch the presentation below:

City's commitment

Although the City has made significant investments (over $7.8 million) in the WQLS area, the ground is still moving at a significant rate. The City will continue to monitor land movement in the WQLS area, but there are no planned major investments at this time. The monitoring will require the City to continue to invest in monitoring equipment that is damaged or destroyed due to land movement. In 2022, the City will spend $65,000 to replace damaged monitoring equipment.

The existing de-watering infrastructure must be maintained, including the pumping wells, horizontal fans, and related infrastructure. In 2021 the horizontal fans were rehabilitated and early indications suggest this was successful. The current estimate to maintain the existing equipment requires an annual contribution of $70,000.

Due to the large costs and unpredictable effectiveness of additional pumping equipment, there will be no more horizontal drains or pumping wells installed in the area at this time. If in the future more drains and pumps are recommended and West Quesnel residents agree to a parcel tax to fund more drains and pumps, Council will consider a parcel tax for West Quesnel. No parcel tax is being considered at this point.

The City will continue to focus on the surface drainage in this area.

Building in the WQLS area
Building information

The Community Charter authorizes the Building Inspector to require a Geotechnical Report to be supplied with a building permit application on any lands they feel may be susceptible. The City has mapped out most areas which have the potential for movement, however site specific conditions outside these areas may also cause the Building Inspector to request a report.

Most development in the West Quesnel Land Stability Area of the City will require a Geotechnical Report to accompany an application although there are some exceptions. Learn more about Building in the West Quesnel Land Stability Area (WQLSA).

For more information contact the Building Department at 250-992-2111 or buildinginspection@quesnel.ca.

For more information about land hazards visit the Getting Started page.

Reports and maps

The City of Quesnel, in partnership with its consultants - Urban Systems and AMEC Froster Wheeler, has compiled a vast library of resource materials, scientific findings and technical reports.

File sizes are large and could take time to download. Please contact City Hall at 250-992-2111 to view hard copies.

History of the WQLS Program
2000 - 2010

2000

Preliminary drilling and installation of instrumentation and GPS system. Large landslide confirmed.

2001-2002

Preliminary analyses and findings require surface and subsurface drainage.

2003-2004

A preliminary pilot test well was installed and resulted in poor results.

2005

Morgenstern completed a detailed investigation.

2006-2007

Detailed geotechnical and hydrogeology studies completed.

2007-2008

The trial dewatering program started and included four pumping wells and two horizontal drains.

2008-2010

The full-scale dewatering design was completed as well as supporting environmental and archeology studies.

2012-2020

2012-2013

The phase I dewatering program included the installation of a subsurface drainage system and ongoing monitoring. 17 pumping wells were monitored for flow and water level and 10 horizontal drain sites were monitored for flow.

2016-2017

The phase II drainage and groundwater monitoring system consists of four pumping wells monitored for flow and water level and four horizontal drain sites monitored for flow. Stormwater mainlines were replaced along Anderson Dr, Abbott Dr, Broughton Ave, Panagrot Ave and Healy St. Roads, and gutters and sidewalks were replaced or added in most of these areas. This phase also included the installation of an outfall area along Anderson Drive. The outfall area filters the stormwater mainline water before it enters Baker Creek.

2018-2020

Monitoring and regular maintenance have been ongoing through this period. Three full years of land movement data have been gathered since the completion of phase II. 47 GPS hubs are surveyed twice annually to provide information on horizontal movement. Historical movements of up to 87 mm per year have been previously observed.

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