Heres the job I'm on now: 1.5 miles of 36 inch sewer line between 17 and 28 feet deep. We are laying along a fairly large creek the whole way with 4 creek crossings. We are digging thru mostly solid rock ( usually about 15 feet of rock) that has been blasted. We usually drag a 3 in. 5 horse pump along with us to dewater with but I was wondering if any of you pipe guys have any other tricks. Pumping works but it is just very time consuming. When the water is not as bad we can over dig the ditch slightly and give the water a place to go before we rock it and grade, but it does waste more rock that way. Just wondering if anybody had any suggestions
Dig up stream...then the water is always down stream .. ..... the water will go behind you as you go ...pumps can be left ..kinda behind ..
Gas pumps lose prime after they catch up with the water. Try electric submersibles. Did you try leaving any wells behind? Sounds like a good time to invest in a genset to run an electric over night, nothings better than starting the day in a dry ditch. Be safe.
Is there enough of a gradient drop to use a siphon? How about a slurry pump on a tractor?
de-watering Wormkiller is on the right track with the electric submersilbles.This is money well spent. If the trench has all been pre-blasted,there will surely be alot of water trapped throughout-especially since being near a creek.Dig in some sump pipes where the manholes will be installed-we usually use 18" Big 'O' plastic pipe on end with slots cut through the sides up from the bottom to about the six foot mark.The trench will be blasted deeper in those areas to allow for the sump in the manhole base,so dig the sump pipe right down below the bottom grade of the manhole.Put some 3/4"crushed stone around the pipe to allow water through the slots.Backfill leaving the end of the pipe above ground level.Do this as many places as possible,so de-watering can take place well in advance of the pipe crew.Set-up some 3" submersible pumps in the pipes.We use 10K silent run generators,which can operate two 3" Flygt electric submersible pumps easily.The pipe crew will carry the same type of pump along the trench bottom,moving along pipe for pipe.Tough slugging at times.The pump is set-up just behind the end of the pipe,a good foot deeper than invert grade.Pump 24/7 if nessecary so the work can proceed in the dry. A trench full of water and an ornery centrifigal gas pump is a bad way to start the day. Good and safe digging, Dominion:canada
This is always the best - but sometimes the geniuses in charge don't let us do it, you know how that goes. Some of these GC's...its like talking to a rock.