Best Management Practices for Dewatering and In-water Work between August 1 and September 30

Follow these standard best management practices that apply to all roadwork projects.

During the reptile overwintering period from September to May, do not do any dewatering or in-water work that will change the water level of reptile overwintering habitat.

Keep in-water work brief.

• If equipment must be operated in water, conduct the work during dry and low-water periods.
• Monitor weather events and time activities accordingly. Only work in dry weather conditions. Stop work during periods of heavy rainfall.

• When deploying turbidity curtains to isolate an in-water work area, deploy them from one point outward, like inflating a balloon.
• When dewatering, install the upstream barrier first, then herd fish and other aquatic species downstream, out of the area to be isolated, before installing the downstream barrier.
• Dewater gradually.
• Carefully salvage and relocate fish and aquatic species from the isolated area to an area downstream.

• If a diversion channel is required to pass water around a dewatered work area, ensure the channel is established prior to starting work, is stable, and can accommodate peak seasonal flow.
• When a diversion channel must provide fish passage, construct the channel with low enough water velocity and rest areas that will allow the species present to pass upstream to access important habitats like spawning areas.

Install intake pipes at least 30 cm above the bottom of the waterbody and screen the pipes with appropriately sized mesh for the fish and species present. Guidance is available in DFO’s Interim code of practice: End-of-pipe fish protection screens for small water intakes in freshwater.

• Regularly inspect isolated areas, dewatering systems, and sediment controls and immediately repair any damage or deficiencies.
• Direct discharge water from dewatering to a temporary sediment control area or vegetated area at least 30 m away from waterbodies. Allow sediment to settle out before returning water to the waterbody
• Re-water slowly to prevent sudden flow surges. Ensure sediment has settled before removing isolating turbidity curtains. Remove downstream isolation dams first and allow water levels to equalize before removing upstream dams.

Salvage coarse substrates and in-stream cover elements, like logs and boulders, from the work area and reuse them during restoration after work is complete.