Natural Resources (OMNR) with respect to species at risk (SAR). Watershed characteristics for the Marentette Mangin Drain Sub-Watershed were determined using information obtained from ERCA’s online GIS database, topographic survey completed as part of The Parkway Project, the City of Windsor Storm Sewer Atlas and field investigations.

Existing Conditions

The Marentette Mangin Drain is an intermittently flowing watercourse and is not considered fish habitat. Based on Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA) mapping, the Marentette Mangin Drain is classified as a Class F drain.

The Marentette Mangin Drain Sub-Watershed has been significantly impacted by residential developments both upstream and downstream of Huron Church Road. These impacts are the result of enclosure, and barriers and diversion of flows. It is noteworthy that the ERCA and OMAFRA mapping have not been updated to reflect the enclosures of the drain and diversion of flows.

The soil characteristics within and surrounding the Marentette Mangin Drain study area were determined based on regional soil mapping obtained from OMAFRA. The soils within the sub-watershed are composed primarily of Berrien Sand, which corresponds to hydrologic soil group (HSG) ‘AB.’ A weighted average curve number (CN) of 63 was calculated based on the existing land use and soil information.

Design Considerations

In general, the design criteria provide the design requirements for the conveyance of stormwater, quantity control, quality control and flood protection. These criteria are summarized in the stormwater management (SWM) report prepared as part of the detailed design of drainage infrastructure for the section of the Windsor-Essex Parkway associated with the Marentette Mangin Drain.

Proposed drainage conditions have been reviewed and hydraulic modeling has determined that there are no adverse impacts on upstream properties in terms of water surface elevations. Additionally, the SWM plan demonstrates that there are no adverse impacts on downstream properties in terms of peak flows during the design events.

Recommendations

We recommend that the drainage associated to the existing Marentette Mangin Drain be constructed in accordance with the Windsor-Essex Parkway New Construction Drawings Sheets D500, D501, D502 and D800. Also attached is a figure identifying the proposed sub-watershed area for the Marentette Mangin Drain.

All of the works recommended shall be entirely on lands solely under the jurisdiction of the City of Windsor and Ministry of Transportation (MTO). However all costs shall be borne by the MTO. Therefore, a detailed summary of the items for construction and cost are not included as part of this letter. Detailed plans & specifications are not included as part of this letter, but they will be provided for tendering and construction and will provide the basis for future maintenance.