Source of Water Quality Impact during Construction Phase
Cofferdam demolition (ie involves wet excavation by backhoes along the central line of the designed river course) after river widening, formation of flood detention pond and embankment;
Drainage from foundation pit for construction of new embankment
Construction of boundary fence and boundary patrol road; and
Site runoff and pollutants entering the receiving waters.
Source of Water Quality Impact during Operation Phase
Changes to the hydrodynamics through the river regulation and thereby affecting the local erosion and sedimentation pattern and water quality; and
Maintenance dredging which may lead to disturbance and re-suspension of river sediments and thereby affecting water quality.
