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Thornton Connecting Tunnel

The Thornton Connecting Tunnel is currently being constructed for the Metropolitan Water Reclamation District (MWRDGC) of Greater Chicago.  When completed it will link an existing underground water infrastructure system to the Thornton Quarry through connecting tunnels and a gate shaft.  The quarry will act as a temporary holding reservoir for wastewater prior to being treated and released into Lake Michigan.

The underground aspects of the approximately $135M project consist of roughly 1,300 lf of 30-ft-diameter concrete-lined tunnel; a tunnel portal structure; a 63-ft-diameter, 340-ft-deep shaft; and a 215 lf, 60-ft-wide by 40-ft-high bifurcation chamber.  The project also includes removal of an existing underground rock plug and tie-in to the existing Indiana Avenue, Tunnel and Reservoir Plan (TARP) tunnel.

Lachel is currently serving as the Contractor’s Engineer of Record for the underground portions of the project, developing the ground support designs for the soil and rock shaft sections and tunnels, preparing the design submittal packages, and coordinating development and submission of final submittal documents to the MWRDGC.