Tips for trench box safety that nobody talks about

Started making this walk-around mandatory with our lead operator last summer when we were laying 12-inch ductile iron on a county water main job. We were using an 8x16 Kundel box, and my biggest headache was actually the bottom gap rather than just the open face. The operator loved to keep the box suspended a good two and a half feet off the trench floor so he wouldn't bind up when pulling it forward with the Cat 320. I had to climb down there and physically show him where the slough from the bottom two feet was spilling under the cutting edge and pinching our bedding stone. It only took one small cave-in under the shield lip to lock a bell joint cockeyed, which cost us four hours of digging it out by hand anyway. Now, before we drop a pipe, we check three things together: the bottom clearance stays strictly under 18 inches, the open face ahead gets knocked down to a 1:1 slope if we aren't using an end panel, and the spoil pile is pushed back a full three feet minimum instead of sitting on the lip. Supers hate the extra five minutes every pull, but we haven't had a joint kick out or a wall collapse since we dialed that in.

Spot on, but another small thing crews always overlook on that walk is the ladder setup. You get the box situated and the gap dialed, but then someone tosses in an extension ladder that barely reaches the top lip without the 3-foot extension past the rim. If somthing does kick loose and you have to scramble, you don't want to be vaulting over a greasy spreader bar. We keep ratchet straps right on the box to lock the ladder rails straight to the spreader eyes so it can't slide laterally when you hit the rungs in muddy boots.

What saved our hides on a deep sewer tie-in was managing the groundwater before moving the shield. First afternoon we hit seepage, the box practically suctioned itself into the muck. Every time the machine tugged it forward, it shook the whole bank loose from the drag.

I threw togather a sump using an old drilled-out 5-gallon bucket wrapped in silt fabric, dropped a 2-inch trash pump in it, and kept the trench bottom bone dry. Once that hydrostatic pull was gone, the box slid forward like butter without the excavator rattling the sidewalls to pieces.

Man I just started on a wet utilities crew two weeks ago and this is pure gold for my notes! Speaking of pulling the box forward though, how do you guys keep your pipe laser from getting totally knocked out of whack every single pull? Every time our operator drags our shield ahead, the whole trench shakes and throws our beam off, so we're constantly crawling in to re-level the trivet. Do people usally mount them high on a pole or manhole instead, or is resetting it every five minutes just part of the deal?