boring under existing piping

huangyhg

boring under existing piping
i need some suggestions............
i've got an existing refinery that some very old and very wide below grade pipe trenches.
i've got to route some new utility (power) under them (+/- 3'-0" below bottom of trench)  in most areas, directional drilling will work.
in one area, i have no outlet access for directional drilling, so it looks like we're stuck hand digging (about 80', 3'-0"deep) around a very congested pipe area.
any experience with trenching equipment that can be pushed through wet mud/sand that deep and that long?
thanks in advance.
jjf
i would consider injecting epoxy grout before excavating and then perform your digging carefully. the epoxy will hold "gel" the soil and allows for excavation without undermining the existing footing or trench. i have used this successfully in the past.
here is one of such product supplier prime resin
good luck.
lutfi
lufti,
thanks for the suggestion.  i had seen some "ground freezing" where a cement grout was injected to fix shifting soils for removal.
just didn't occur to me for this one.
jjf
can you put down a pit and jack a casing through? how large is the conduit? can you access both sides of the trench?
sometimes bentonite slurry method is used for excvating almost vertical but this method is very specific to site and requires experience.