Replies

1. 
   CAGIV | Oct 17, 2003 06:45am | #1

   How wide?

   Just for running cable or pipe? 

   
   

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   Edited 10/16/2003 11:47:21 PM ET by CAG

2. 
   4Lorn2 | Oct 17, 2003 08:25am | #2

   Estimating for trenches is an art form. An old boss tried to teach me. Problem is there are a lot of variables and a tight cap. Go too high and the local handyman will get the digging part of the job. This greatly complicates things when he gives up with half the trench undug.

   Another major problem is when he fails to meet the minimum depth and you still have to run the cable or conduit. In the later case the HO refuses to pay for a ditch already done and yet your the person facing the inspector with a trench too shallow. There are a lot of handymen who either can't read a tape measure or lie like a rug. If you know the HO or local labor is going to do the digging it has been suggested that you add half the cost of what it would cost to dig it yourself to the remainder of the job. If you still get the job and the digging was done well you can return the excess. Your call on that.

   Biggest asset in estimating a trench is knowing the local digging conditions and how any lines are typically run in the neighborhood. Too many utilities or not knowing their locations makes a big difference. Calling "No cuts" or similar utility marking is essential but not without limitations. Most services will only guarantee the marked location within 18" or so. Also they don't usually check non-company owned lines. So feeders to wells and outbuildings, sewer lines and private water lines are not included. An old boss of mine once ran the Ditch Witch through a twelve line main manifold for a sprinkler system. Lost money on that one. So it goes.

   Knowing what to expect underground allows you to estimate how much of the trench will need to be dug by hand. Hand digging is even more dependent  on the soil. Hard pan, a dry mix of clay and sand slightly softer than old concrete, sugar sand, sand so fine and soft that the angle of repose, how well it stacks, is about 30 degrees and any soil with roots or rocks can make a short hand dig into an all day ordeal that eats manpower, backs and your profit if you didn't include the extra labor in the estimate.

   A Ditch Witch or backhoe can make short work of many ditches if you don't dig through too many underground lines. They are great time savers but they are not immune especially tough soil conditions. Large rocks and roots can make running a trencher resemble riding a bull. Bad conditions, hard pan and clay, can slow a powerful backhoe. Boulders can stop them cold.

3. 
   SledBC | Oct 17, 2003 08:30am | #3

   Don't you have contractors in your area with mini-excavators? A job like that should take about an hour, would cost me $60 CDN and then we would either backfill by hand or lay the conduit/cable immediatly and have him backfill it before he leaves. Machinery works wonders, just had 4-36" diameter x 4 foot deep holes drilled for some concrete pillars, took the guy 45 minutes, cost $75.

4. 
   IMERC | Oct 17, 2003 08:57am | #4

   Go rnt a ditch witch.. the bigger the machine. the easier the dig.

    

   Who ever invented work didn't know how to fish....

1. 
   john | Oct 17, 2003 09:53am | #5

   Go rnt a ditch witch.. the bigger the machine. the easier the dig

   But bear in mind the info in 4lorn's excellent post. No point in digging trench at a foot a minute if you break a cable or pipe in the process!

   John

1. 
   IMERC | Oct 17, 2003 11:31am | #6

   Call locator.... Then put the ditch in to fit need even if becomes a 40 or 50 foot trench.

   Before he digs he has to call locator anyways.... It's the law.... 

   Who ever invented work didn't know how to fish....