that are at-grade, the minor system will be designed to convey the 10-year design storm flow and the major system will be design to convey the 100-year design storm flow.

Stormwater Quantity Control – Post development peak flows will be controlled to pre-development levels for a range of design events up to and including the 100-year event.

SWM Pond 5 operating characteristics are summarized in Table 9.4 of the SWM Report. The 24-hour duration results were summarized and presented in the table, since the 24-hour duration produced the most conservative storage requirements. The table presented the peak discharges/outflows from Pond 5 during the 5-year and 100-year events to be 0.29 and 0.45 m3/s respectively.

Works for the Marentette-Mangin Drain will be completed under a Letter of Opinion in accordance with Section 77(3) of the Drainage Act.

A copy of the main body of the SWM Report is provided for reference as Appendix A.

2.3.2 Report under Section 77 of the Drainage Act

The following summarize the information provided in the report prepared by PEI under the provisions of Section 77(3) of the Drainage Act that we consider most relevant to this undertaking.

The report concluded that if the work were carried out in accordance with the drawings and specifications, that the portion of the Marentette-Mangin Drain being improved can proceed without adversely affecting any person(s) and / or property.

The total contributing area to the sewer inlet near the Lambton St. Cul-de-sac is approximately 33 ha.

The report recommended that the drainage associated with the Marentette-Mangin Drain be constructed in accordance with the Windsor-Essex Parkway New Construction Sheets D500, D501, D502 and D800.

A copy of the entire report is provided for reference as Appendix B.

2.4 Basis of Hydrologic Modelling

From 1982 through 2013, the Water Survey of Canada (WSC) had maintained a stream gauge (Station No. 02GH004) that recorded water levels and flow rates on the Grand Marais Drain at a location immediately upstream of Huron Church Road. The flow data generated by the gauge had been used to calibrate numerous hydrologic models within the Grand Marais Drain watershed over the past 30 years, including the hydrologic models that formed the basis for the design of drainage elements within the Parkway project. This gauge was decommissioned and removed during the construction of the Parkway. A new gauge has since been installed by WSC slightly upstream of the old gauge.