As noted previously, we estimate that at a minimum, the boundary of the eddy flow zone would extend from the offshore limit of the Kennette infill to the downstream shoreline at a 20 degree angle. The training jetties have been extended to this limit.

The principal advantage to this strategy is that the works could be undertaken independent of the Kennette infill works. The proposed design would however be subject to the approval of the Essex Region Conservation Authority and the Department of Fisheries and Oceans.

The principal disadvantages to this strategy are:

• • The additional construction cost associated with the extended outlet jetties as compared to the original design. A conservative estimate suggests that the added cost of the additional 4,100 additional tonnes of rock would be in excess of $300,000;

• • The extended outlet would occupy a significant portion of the new fish nursery habitat proposed by Kennette. Additional compensatory works would likely be required; and

• • The embayment area that is part of the current Kennette proposal would be significantly reduced in size and would be substantially sheltered from any river current and water circulation.

ii) Alternative C

This design solution represents a compromised solution, consisting of moderate adjustments to both the Broadway Drain Outlet compared to the original design) and a moderate adjustment to the proposed infill works at the BBA site. The alignment of the new shoreline along the southerly portion of the Kennette infill would be altered from the original design in order to reduce the size of the eddy zone or recirculation zone. The most northerly training jetty would be replaced with shore protection that flanks the BBA property. The southerly training jettie would be extended to the estimated limit of the eddy flow zone. The general design concept is illustrated in Figure 2.

The principal advantages to this strategy are:

• • The estimated construction cost of Alternative C would generally equal the cost of the original design, both in terms of the drain outlet and the BBA infill.

• • The Broadway Drain training jetty ( only a single jetty is required) would not need to be extended as far as required in Alternative A;

• • The size of the eddy zone created by the Kennette infill would be substantially reduced from the original infill design;

• • The impact of the Kennette infill on nearshore coastal processes would be substantially reduced, as compared to the original infill design;

• • The ‘groyne’ effect of the Kennette infill would be substantially reduced, as compared to the original infill design, which would reduce the capacity of the area downstream of the infill to accrete sediment;

Design Summary for Broadway Drain Outlet – January 12, 2016

Gordie Howe International Bridge