2.4km sewer tunnel in St.Louis

Affholder Inc. has been awarded a contract to construct the 2.4km I-270 Sanitary Relief Sewer tunnel project in St.Louis, Missouri, U.S.

Using a Lovat TBM, Affholder will bore approximately 300m through limestone varying in strength from 75Mpa to 150Mpa. The remaining 2.1km is expected to be driven through mixed strata that should mainly consist of clay with some gravel, shale and chert.

Despite most of the alignment running under the water table, water is not expected to pose significant problems because of the separation afforded by the clay.