Broadway Drain South Jetty Construction Methodology

Construction of the rock jetty for the Broadway Drain Realignment shall generally proceed in the order specified below. Additional details regarding fish salvage efforts and water quality protection measures are detailed in the sections that follow. Modifications to the stated methodology may be recommended by the Fisheries Biologist or by the Contract Administrator (CA) depending on field conditions. The Fisheries Biologist shall be on-site full-time during all in-water work in the Detroit River.

The construction of the Broadway Drain south jetty will generally follow the methods outlined below:

1. Seine netting will occur from the shoreline (or previous limit of work in the river) and encompass the active work zone immediately prior to placing rock material in the river in an attempt to capture fish which may be present, as well as to help direct fish into open water. This will be performed on a daily basis prior to start of work, in the areas of the river which are wadable.
2. Fish salvage operations will be completed with minnow traps set in a 15m grid within the deeper water areas of the work area for two days prior to construction activities. Traps will be pulled twice each day. During construction, the traps will be located outside of the active work zone and will be incrementally moved out deeper as the works progress. The traps will be checked each morning prior to the start of construction and any fish captured will be released downstream of the work area.
3. Prior to any stone materials being placed into the Detroit River, they shall be inspected for the presence of excessive dust on their surface and washed as necessary. Any rinsing shall use clean water and occur at a location where wash water will not reach the Detroit River or any other waterbody.
4. Using an appropriately sized excavator, the construction of the rock jetty shall commence from the future outlet of the Broadway Drain and slowly work out into the river.
5. The revetment, as shown on Landmark drawing 14-043-SUP1 dated 2016/07/26, will be keyed into the existing slope of the riverbank using slow, measured strokes to minimize the amount of sediment being generated. Care will be taken to ensure that over excavation will not occur and a turbidity curtain will be in place for this nearshore excavation work.
6. The gabion stone core shall be placed without keying into the river bank or bed. When placing material in the Detroit River, the rocks shall be released slowly and as close to the bottom as possible to reduce splashing and uncontrolled roll-a-ways.
7. No construction equipment will be allowed to travel on exposed riverbank or riverbed. As such, the excavator will build its way out into the river starting from the shoreline and support itself on either the gabion stone or armour stone at all times. The edges of the rock jetty shall be constructed before the center.
8. Once the gabion stone core has been completed to the design specifications, the armour stone jetty construction shall begin.
9. At no point shall the excavator support itself on the gabion stone core after it has been constructed to design specifications. Following the same process as for the gabion stone core, the excavator shall build its way out to the edge of the gabion stone core while only supporting itself upon the armour stone. Starting from the shoreline, the armour stone jetty shall be built following the same “outside-in” methodology as the gabion stone core.

Construction of the jetty shall be conducted in a slow, measured manner so as to prevent causing any disturbance to the riverbed. Turbidity levels in the Detroit River shall be visually monitored by the Fisheries Biologist during construction. Should the Fisheries Biologist determine that excessive sediment is being generated as a result of AMICO’s operation, work shall temporarily cease until water turbidity is reduced to acceptable levels as determined by the Fisheries Biologist.