Sediment releases at 1,100-MW Site C hydropower project in Canada prompt environmental orders

By March 31, BC Hydro must deliver an assessment to British Columbia’s Environmental Assessment Office (EAO) of the potential effects to fish and fish habitat associated with construction of the 1,100-MW Site C hydropower project and its “historic sediment releases to the L3 and Peace River,” according to an EAO order issued this month.

The Site C project is being built on the Peace River near Fort St. John in British Columbia, Canada.

On Aug. 30, 2016, EAO said its compliance and enforcement personnel observed staff employed by Site C contractor, Morgan Construction and Environmental Ltd., pumping sediment-laden water directly to the L3 watercourse from a flooded work area at the North Bank Haul Road crossing.

The L3 watercourse is classified as an S4 fish-bearing stream.

An EOA report indicates another incident occurred on Feb. 16 in which staff employed by project contractor, Peace River Hydro Partners, pumped sediment-laden water from a flooded work area to a ditch that connects directly to the L3 watercourse.

On Feb. 28, Senior EAO Compliance and Enforcement Officer, Chris Parks, received from the project independent environmental monitor a report on the second incident and details of ongoing erosion and sediment transport noncompliance in the L3 ravine that began taking place on Nov. 8, 2016.

In the order delivered to the utility on March 3, Park wrote that he has determined BC Hydro is in continued noncompliance with conditions No. 2 and No. 69 of the Environmental Assessment Certificate and the previous order. This determination is due to the utility’s failure to adhere to measures to control runoff water and sediment during the construction of the project in and immediately adjacent to the L3 Ravine.

The noncompliant erosion and sediment transport from the Site C construction site has resulted in observable deposition of sediments in the L3 watercourse, and may have adversely affected fish and fish habitat in the L3 watercourse and Peace River, according to EAO.

EAO ordered BC Hydro to submit a water-quality monitoring plan specific to the L3 watercourse and Peace River downstream, including in part, the installation of turbidity-monitoring equipment and reporting all future sediment releases.

The assessment, in part, must include the following:

  • Describe fish and fish habitat values in the L3 watercourse and Peace River side channel;
  • Identify methodology to determine effects to fish and fish habitat associated with sediment inputs to the L3 watercourse and Peace River side channel;
  • Identify if adverse effects have occurred or are likely to have occurred; and
  • If adverse effects are identified as having occurred or that they likely have occurred, identify methods to address effects to fish and fish habitat.

According to published reports, BC Hydro spokesman Dave Conway issued a statement saying the Crown corporation is working closely with Peace River Hydro Partners and the EAO to meet compliance mandates.

“We have an erosion and sediment control plan in place; however, we experienced some excess water challenges last month after heavy rainfall and the warmest winter weather for the region in 30 years.”

Site C is also bringing in an “expanded and more intense erosion and sediment control program” that will include reporting, mapping and weekly updates, Conway said in an email.

According to BC Hydro, contractors have carried out more than 1,000 erosion and sediment inspections at Site C since October.

Unrelated to the L3 watercourse issue, on Feb. 27 HydroWorld.com reported BC Hydro assessed a 400-meter-long tension crack that appeared during construction of a haul road to support excavation work at Site C hydro project.

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Gregory B. Poindexter formerly was an associate editor for HydroWorld.com.

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