Offshore Wind Power Projects in the Great Lakes - Ministry of ...

Offshore wind power projects in the Great Lakes: Background information and science considerations for fish and fish habitat
Effect
Sedimentation
and turbidity from
construction
activities
Sedimentation
and turbidity from
construction
activities (cont’d)
Negative impacts
from invasive
species
colonizing turbine
structures and
scour protection
Associated wind
power activity
Construction
(dredging and
cable trenching)
Construction
(dredging and
cable trenching)
Physical
presence of
structures
Predicted
magnitude of
effect without
mitigation
(uncertainty)
Medium
(Low)
Medium
(Low)
Mitigation strategy
• Minimizing disturbance during
cable laying
• Foundation type
• Choice of dredging equipment
• Controlling turbidity
Low (High) • Project location
• Periodic removal
• Deterring colonization and use
by non-native species
Examples of specific mitigation
measures
• Single-operation process (i.e.
trenches excavated and cables
buried at once); Placing cables
on top of lake bed (instead of
burial); Horizontal directional
drilling below lakebed of
sensitive nearshore areas for
cable landfall; Cofferdams
• Monopile instead of gravitybased
• Use hydraulic dredges that
reduce siltation instead of
mechanical dredges
• Silt curtains and other turbidity
barriers; Bubble curtains;
Restrict dredging to low wind
and wave energy periods
• Avoid project placement in
boundary areas
• Mechanical removal of
encrusting invertebrates
• Choice of scour protection
materials that reduce
colonization; Use anti-fouling
agents to limit colonization
Examples of potential
limitations for application
in the Great Lakes
• Not burying cables might
increase EMF exposure,
potential fishing gear
entanglement, and damage
or movement from ice;
Horizontal directional
drilling increases chance
of “frac-outs” which cause
release of drilling muds
and fluids
• Pile driving of monopiles
will cause noise
disturbance
• Hydraulic dredges create
more noise than
mechanical dredges
• Strong currents and waves
might limit capability of
using turbidity barriers or
bubble curtains
• Could prove very difficult
to predict or control range
limits
• Anti-fouling chemical
agents could cause water
quality issues
Aquatic Research and Development Section 12