Coquitlam Dam Seismic Upgrade Project ... - BC Hydro

3.13. HYDROLOGY
Coquitlam Reservoir has been operated at lower than normal operating levels since December
2000 to El. 149 due to dam safety concerns. In addition, a water management plan will be
prepared to evaluate and reduce the risk of spill during work in the spillway channel. An
emergency plan will be in place to remove all equipment and construction materials from the
floodplain in the event of a spill.
Existing flow agreements stipulated by the water use plan will be satisfied. Some temporary
reductions in flow may be required to install and connect the headtank fish water release
pipeline. If flow interruptions are required, DFO will be advised and consulted during the
planning stages of this work.
3.14. SITE RESTORATION AND DEACTIVATION
Site restoration and access road deactivation will be required to reduce erosion and water quality
concerns. Once work is completed within a site or when a particular section has been completed,
the site or area will need to be stabilized and restored. Since this is a multi-year Project, a
progressive approach to restoration will be required where restoration and stabilization is an
ongoing process. It will not be acceptable to keep an entire site open and complete all of the
restoration requirements at the end of the project. Ongoing restoration of the work sites will
include:
• re-contouring the site to ensure it is free-draining and to ensure slopes are graded to prevent
erosion;
• restoring drainage patterns to pre-construction condition or to the satisfaction of the Project
Manager; and
• hydroseeding the area with an approved erosion control seed mix. Note that topsoil may be
required in some areas depending on the fill material to ensure sufficient ground cover is
established.
These conditions also apply to all temporary and permanent access roads that have been
developed for the works as well as all other areas disturbed by the works.
Final restoration of the working areas has not been finalized. Final restoration of the working
areas will include:
• grading and shaping the disturbed areas to ensure they are free-draining and stable;
• excessively compacted areas will be scarified to a minimum depth of 150 mm;
Coquitlam Dam Seismic Rehabilitation Page 23
Environmental Management Plan – Version 4
June 15, 2004