and detail drawings. Refer to the Landscaping Planting Plan drawings for details on the planting strategy for SWM Pond 5.
A geotechnical and hydrogeological investigation was completed during the 60% design stage to confirm liner requirements, entitled Estimates of In/Outflows – Stormwater Management, Fish Habitat Compensation Ponds and Realigned Drains (PIE/AMEC, 2012). The report indicates the pond is in contact with the Upper Granular Deposits and is expected to gain water during wet periods, and lose water during dry periods. Accordingly, an impermeable liner system will be required for Pond 5.
To ensure that the SWM pond continues to operate as designed, a pond maintenance plan should be developed for routine maintenance of the facility and should include:
- Frequency of pond inspection (during wet weather operation) to assess its performance and operation
- Repair and maintenance protocols
- Frequency of removal of accumulated sediment.
9.5 Erosion and Sediment Control (During Construction)
An Erosion and Sediment Control Plan will be developed by PIC and submitted under separate cover.
10 Conclusions
This report documents the detailed design SWM plan and drainage design for the section of The Parkway that is contributing flows to the Marentette Mangin Drain sub-watershed. The PDR SWM plan developed in support of the PDR was used as the basis and was further refined by integrating hydraulic, hydrologic, highway, structural and environmental design considerations to meet the requirements of the Project Agreement. Stakeholder agencies were consulted to ensure that the detailed design meets the current policy requirements and concerns associated with the Marentette Mangin Drain. In view of the objectives stated in Section 4.1, the following conclusions are provided:
- The Parkway drainage design conveys the 100-year return period event flows for depressed sections of the highway and 10-year return period flows for sections at-grade.
- The SWM plan is developed to demonstrate that there are no adverse impacts to downstream properties in terms of peak flows.
- Pond 5 has been sized to provide enhanced water quality treatment. Additional passive water quality treatment will be provided via the landscape planting strategy and vegetated swales.