10 Mile Slide Update on HWY 99 - Single lane, alternating traffic and load restrictions ongoing

Dec 02, 2016
Affected Communities: 
District of Lillooet, Electoral Area B
Status Updates: 
December 7, 2016: Province commits $60 million to address 10 Mile Slide. Work to commence summer 2017.



On September 27, 2016, Highway 99 was closed at the Ten Mile (Fountain) Slide, about 15 km north of Lillooet, on Xaxli'p reserve lands, after concerns raised about sudden slumping on the road. The road re-opened on October 5 to single-lane, alternating traffic. A weight restriction of 50% legal axle load remains in effect between Fountain Valley Rd through to Pavilion-Clinton Road.  Drive BC recommends that travellers expect minor delays, and watch for flagging personnel. 

December 1, 2016 - Update

Ministry of Transportation and Infrastructure (MoTI) has advised as of December 1, 2016, that:

  • The highway surface is still holding well.
  • Cracking and sinkholes have starting forming along the grader berm and the outer edge appears to be sinking. The movement on the outer edge is likely due to the recent wet weather – similar behaviour should be expected during winter conditions.
  • On site monitors have been identifying problems areas and MoTI staff are developing plans to address these.
  • There were flagging challenges last week when the accident closed Highway 1 south of Spences Bridge; the detour traffic was heavy and flaggers were repositioned in an area on the south end to accommodate heavy loaded trucks with a turnaround spot.
  • MoTI is tendering a contract to install approximately 30 soil anchors. Work is expected to commence in January.
  • Once the short term stabilization has been installed, the Ministry will work to reconstruct two lanes for Highway 99.
  • Single lane alternating traffic on Highway 99 is still in effect – expect minor delays and watch for flagging personnel. Weight restrictions of 50% legal axle load are still in effect; CVSE is providing enhanced enforcement and will continue to do so until the weight restrictions are lifted. Flaggers and monitors remain on site 24hrs a day.
  • MoTI engineers and surveyors will continue to monitor the slide area to ensure single lane highway operations are safe for the travelling public.
  • DriveBC is up to date and includes appropriate messaging regarding highway operations and associated load restrictions.
  • Safety is our top priority and MoTI and Xaxli’p continue to work closely together.

The Squamish-Lillooet Regional District will continue to share updates as we receive them.


The area is prone to geological instability and has been an ongoing concern for many years.

The slide, which is up to 2 km long and about 400 m wide, has been slowly slipping toward the Fraser River. BC Highway 99 runs through the slide path, making the soils beneath the road surface unstable. The CN Rail line is located above the slide path.

Due to its proximity to the highway and rail line, the Ministry of Transportation and Infrastructure (MOTI) has been monitoring the slide closely for many years, and significant works have been undertaken to stabilize the slope.

Earlier this year, MOTI retained BCG Engineering to assess the slide area and provide design options to address the slope instability. A Project Liaison Committee composed of representatives from Xaxli’p, the five other northern St’át’imc communities (Sekw’el’was, T’it’q’et, Tsal’alh, Ts’kw’aylaxw, Xwísten), District of Lillooet, SLRD, CN Rail, and affected utilities was formed to provide feedback as the project progresses and to receive ongoing project updates. The project is ongoing.  

Highway 99 is an important travel route for residents and businesses in Lillooet, SLRD Areas A and B, and northern St’át’imc Territory to access goods, services and health services. It’s estimated that more than 500,000 vehicles cross the Ten Mile Slide each year, including residential, commercial, industrial and tourist traffic.

The SLRD, District of Lillooet and northern St’át’imc communities have long advocated for a permanent solution to address the slope instability at the Ten Mile Slide. SLRD officials met with Premier Christy Clark, Transportation Minister Todd Stone and Minister of Jobs, Tourism and Skills Training Shirley Bond on September 29, 2016 at the annual Union of BC Municipalities convention in Victoria and requested that immediate action be undertaken to address the Ten Mile Slide and make travel through the area safer and more reliable for local residents, visitors, commercial enterprises and the travelling public.  

On October 7, Minister of Transportation and Infrastructure Todd Stone and Fraser-Nicola MLA Jackie Tegart visited the 10 Mile Slide. The Minister later posted this update to his Facebook page:

Last Friday, my colleague, Fraser-Nicola MLA Jackie Tegart, and I toured the location of the Ten Mile Slide, 17 km NE of Lillooet. This slide area is part of an ancient Tunnel Earth Flow that has been active for decades. We walked the entire length of the slide area, and also hiked about 100 m upslope of Highway 99 near where CN Rail’s tracks are located. Proving the point that pictures and briefing notes are always limited in the scope and context that they can portray, this tour provided us with a terrific opportunity to see first-hand just how massive the area affected really is – the slide dimensions are 200m wide and about 300m in length.

During our visit, we were honoured to meet with four area First Nations Chiefs: Chief Darrell Bob of Xaxli’p (Fountain), Chief Michelle Edwards of Sekw'al'was (Cayoose Creek), Chief Kevin Whitney of T'it'q'et (Lillooet), and Chief Larry Casper of Tsal'alh (Seton). While on-site, we also had a productive meeting with Mayor Marg Lampman and a number of her Lillooet Council colleagues, as well as with Mickey Macri, Squamish-Lillooet Regional District Director for Electoral Area B. Along with key MOTI staff, we appreciated the opportunity to hear first-hand the concerns of local area residents, and to provide detailed information as to the current status of the slide, as well as MOTI efforts underway to assess and execute on next steps.

The ministry’s geotechnical engineers have been closely monitoring the slide area by collecting and reviewing data from gauges to ensure appropriate safety measures, traffic control and emergency protocols are implemented to protect the safety of the local area residents and the travelling public.

We are all in agreement that the Ten Mile Slide area of Highway 99 is amongst the most unique and challenging geographical sections of highway in all of Canada. That being said, we are committed to engineering and constructing emergency access in the short-term, working very closely with Xaxli’p to address their immediate community needs. In addition, we are focused on developing solutions for long term stabilization of the road, and we have engaged external engineers, a technical peer review committee, an expert review panel, and independent engineering consultants hired by Xaxli’p to assist in that effort.

Above: Ten Mile Slide on Highway 99 15 km east of Lillooet— site visit October 7 2016, with Barb Wiebe, Marg Lampman, Todd Stone, Jackie Tegart, John Courchene, Mic Macri and Scottie. Photo courtesy Jackie Tegart, MLA.


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