Highway Creek Acid Rock Drainage Project

The Highway Creek Acid Rock Drainage Project is located approximately 32 km west of West Kelowna on Highway 97C at the crossing of Highway Creek.

During construction of Highway 97C the road cut through a mineralized area at the Highway Creek crossing, resulting in acidic, mineral rich seepage (called Acid Rock Drainage (ARD)) into the highway ditches, and ultimately, Highway Creek.  MOTI has now constructed a water treatment facility to treat the affected water.

Location

The project site is on BC MOTI right-of- way for Highway 97C. 

It is located at a latitude of 49°54'37.61"N and longitude 120° 4'34.97"W.

Project scope

• Capping road fill in the area with an impermeable cover to reduce the volume of acidic water generated. This cover prevents clean water (i.e. rain and snow melt) from contacting the acid generating rock under the road. In the median, the engineered cap extends 1.7 km to the east of Highway Creek, and 0.12 km to the west. In the ditches, the cap extends on either side of the highway for approximately 0.8 km, and on the 18-m high embankment slopes on either side of the highway at Highway Creek.
• Treating collected water by constructing a passive water treatment system (PWTS) consisting of a series of components, such as an acid neutralizing chamber, biochemical reactor cells, aerobic polishing cells, a vegetated settling basing and limestone ditch
• Treating groundwater and further treatment of collected water by constructing an enhanced wetland treatment system (EWTS) consisting of flushed limestone beds, settling basins, surface flow wetlands and a final outlet pond with a diffuse release to Highway Creek.
• Protecting and restoring Highway Creek by lining the creek downstream of the highway and building high-quality fish habitat through riparian improvements and in-stream complexing.

Project facilities

The project site includes a passive water treatment system (PWTS) and an enhanced wetland treatment system (EWTS). The two function as one system.

Passive water treatment system

The PWTS functions as a treatment train that starts with acidity neutralization, followed by two sequential biochemical reactors (BCR), two sequential aerobic polishing cells (APC), a vegetated settling basin where evaporation will also take place when climate conditions allow, and a limestone ditch.

Depending on water flow, the treated water is routed from either the settling basin or the limestone ditch to the first surface wetland (SFW1) component of the EWTS for further treatment.

Enhanced wetland treatment system

The EWTS has two flushed limestone beds (FLB) that flow into settling basins and are intended to neutralize acidity. These basins then flow into an inlet pond in the wetland and progressively treated water flows between unlined surface wetlands (SFW) separated by lined compostable organic media beds (COMB).

The discharge from the EWTS is via exfiltration to ground when water levels in the wetland are lower than elevation 1,570.3 m, and additionally via a rip-rap berm adjacent to Highway Creek when wetland water levels are higher than elevation 1,570.3 m.

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Legend:

Illustration of the PWTS and EWTS treatment train components on the project site landscape.

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Proposed activities

MOTI is currently operating under a temporary waste discharge approval and has now applied for a permanent waste discharge approval for the long-term operations of the site, which includes water quality monitoring and routine maintenance.

Discharge via the outlet pond in the EWTS will be 24 hours per day 7 days a week, 365 days per year.

Flow rate and volumes vary over the course of the year. However, based on historical water volumes, approximately 55,000 m³ (equivalent to 22 Olympic sized swimming pools) will be discharged from the site annually.

Waste characteristics

As per the temporary waste discharge approval, discharge characteristics are not to exceed the concentrations or units listed below for the following chemical parameters. The parameters and units are not expected to change in the long-term waste discharge permit application.

Waste in metric scientific units

Parameter	Maximum or Minimum	Concentration and Units
pH	Maximum	9pH units
pH	Minimum	6pHunits
Total Sulfate	Maximum	750 mg/L
Total Antimony	Maximum	400 µg/L
Total Aluminum	Maximum	9 µg/L
Total Arsenic	Maximum	10 µg/L
Total Beryllium	Maximum	0.15 µg/L
Dissolved Cadmium	Maximum	0.2 µg/L
Total Chromium	Maximum	4 µg/L
Total Cobalt	Maximum	7 µg/L
Dissolved Copper	Maximum	5 µg/L
Dissolved Iron	Maximum	1000 µg/L
Total Iron	Maximum	2000 µg/L
Total Lead	Maximum	4 µg/L
Total Manganese	Maximum	5000 µg/L
Total Nickel	Maximum	30 µg/L
Total Selenium	Maximum	4 µg/L
Total Thallium	Maximum	0.8 µg/L
Total Uranium	Maximum	8.5 µg/L
Dissolved Zinc	Maximum	20 µg/L
Total Suspended Solids	Maximum	25mg/L

Duration of project

Since December 1, 2023, MOTI has been operating with a temporary (15 month) waste discharge approval  (Authorization #110118 (PDF, 7MB)  which was based on: .

• Technical Assessment Report  (PDF, 30MB) 

MOTI has applied for a permanent waste discharge approval for the long-term operations of the site after the temporary approval expires.

MOTI expects to operate this site in perpetuity or until the ARD issues have resolved.

Engagement

MOTI has engaged with First Nations in the area for the past several years and has included bands in construction activities and monitoring opportunities.

This is the first public notification opportunity for the project.

Authorizations

• MOTI is operating pursuant to the terms of the temporary waste discharge authorization (Authorization #110118) (PDF, 7MB)