This microtunneled installation of 48″ sanitary line under an interstate had two tunnels. Each was 60″ diameter, one was 725LF, the other 530LF. They shared a shaft.
The owner specified a grouted annular space for the tunnels. The long pumping distance and relatively tight annulus drove the need for a highly mobile, lightweight grout.
CJGeo placed 270CY of CJFill-ST36 (36ksf unconfined compressive strength) cellular grout to fill the annulus on both tunnels. Because the shared shaft wasn’t easily accessible, grouting was performed from each end towards the shared shaft over two back to back days.