The MCPWO completed an asset management plan in 2018 and determined that although the enclosed 11.5 Mile Relief Drain is in good condition, pollutants typical of an urbanized drainage area are being captured by the drain, conveyed through the system and discharged directly into Lake St. Clair. Pollutants may include sediment, hydrocarbons (oils/grease), nutrients from fertilizer, and floatable trash. The MCPWO has prioritized improving water quality into Lake St. Clair by reducing stormwater pollutants from drainage systems under their jurisdiction.

The drain at the outlet to the lake is approximately 28-feet wide and extends into the lake via a sheet pile channel covered by a concrete deck. Secondary sheet pile walls adjacent to the channel serve as sea walls and help to form a pier into the lake. A triangular sheet pile structure exists in the lake at the end of the drain to protect the channel walls from ice damage.

The drain discharges directly to Lake St. Clair in a vacant lot, which is owned by the MCPWO and has been identified in the City of St. Clair Shores’ (City) master plan as an opportunity to improve public access to the lake. The MCPWO, Macomb County Planning and Economic Development, City of St. Clair Shores, and City of Roseville partnered to develop conceptual alternatives for addressing stormwater pollution and improving public access to the lake.  

A community planning grant from Southeast Michigan Council of Governments (SEMCOG) was awarded to project partners to develop design concepts for reducing stormwater pollution and improve public access to the lake. In January 2020, a team of engineers (Fishbeck and ASI) and architects (Hamilton and Anderson) were hired to prepare the conceptual design plan and develop cost estimates for addressing stormwater pollution and improving public access to the lake. Engineers have evaluated conceptual designs using both high and low water levels in Lake St. Clair to ensure no adverse impacts to drain performance.  

The proposed concept reduces stormwater pollution by means of an underground chamber on the drain that incorporates a sump and baffles system to capture sediment and floatable trash. As water flows through the pipe, sediment drops to the bottom of the sump and floatable trash is captured by the baffles. Sediment and debris levels in the drain would be monitored by MCPWO maintenance crews and removed on a routine schedule. Design goals are to treat up to 300,000,000 gallons of stormwater annually while capturing 270 pounds of phosphorus and 35 cubic yards of suspended solids before entering the lake.  
 
An approximate 0.68-acre area would be available for public use as a St Clair Shores Park. The City is interested in public input concerning the function of the park, which currently is proposed as a passive recreation space consisting of seating areas, and a walking pathway to the lake along the existing decking and a boardwalk. Other possibilities could include a fishing pier or a kayak way station. A gravel access lane along the southern edge of the park will be constructed to allow for drain maintenance access.

The final concept will be released in early 2021. The project team will use the approved concept as an impetus for grant funding for the proposed improvements going forward.