The tunnel was constructed entirely in rock and is part of Metropolitan St. Louis Sewer District’s (MSD) Project Clear.
The tunnel’s main objective is to intercept flows and to take offline the interim Fenton Wastewater Treatment Facility.
The 6.8-mile-long tunnel is 96 inches in diameter and reaches depths ranging from 78 to 286 feet at a slope of 0.1%.
Six drop structures are included within the design to accommodate as much gravity flow to the tunnel as practical and economical.
