Soil Nail installation costs

[sgsibob]

Does anyone have a range of pre-each or footage unit rates for installation of soil nails (just the nails, not the full wall with shotcrete)? Essentially this is just a long, nearly horizontal self drilling soil anchor. I could use cost data for self drilled nails or open-hole drilled nails, or both.

 

[TomPetracca]

sgsibob:

Just did a residential job in NY, - 10' helices into the ground - on average...costs were $1,100 per helix.

Tom

 

[sgsibob]

Thanks. Think a drilled and grouted anchor would be about the same?

 

[PEinc]

Drilled anchors, such as helical anchors, should be much cheaper than grouted anchors if there is a small number of anchors or if the design load is not too great (maybe less than 40 kips).

Mobilization of equipment for grouted anchors is more than that for helical anchors or anchors such as Manta Rays or Sting Rays. Grouted anchors also have curing time which costs money.

However, grouted anchors can be installed in many ground conditions which will not allow helical, mants rays, or Sting rays to be installed. And, generally, grouted anchors can be installed to higher capacities.

Specialty contractors who install tieback and tiedown anchors nationwide on a large scale usually install grouted anchors using high strength threadbar and/or strand tendons.

 

[clayR]

Hi sgsibob,
Many Dept. of Transportations keep average unit prices for items of work, for example I think Txdot bids soil nail walls by the unit price of facing as well as by the length of soil nail. This would be a good place to begin.
As far as comparison between a conventional grouted threadbar and hollow groutable bar the issue becomes
more complex. The problem with a hollow groutable bar is hole size produced by the sacrifical bit, (The bit stays on the end of the bar). It may become impractical in soils with low allowable adhesions when compared to say an 8 inch diameter bore hole. On the other hand in cemented soils and rock nailing applications it becomes a different story. cr

 

[PEinc]

Be careful of using DOT prices for any kind of work unless you know something about the project. Bid prices may have nothing to do with actual costs. The DOT prices could have been front loaded by the contractor for early work items or lowered for later work items to improve project cash flow.

FHWA-SA-96-069, Manual for Design & Construction Monitoring of Soil Nail Walls, lists information, including cost per square meter, for a number of soil nail walls. One of my jobs is listed as the most expensive wall - much higher cost than most of the others. However, the listed cost was based on a crazy bid price that was inked in too early by the estimator. The actual cost was a fraction of the listed cost. So, be careful. If you want good cost information, call a specialty subcontractor who does soil nailing every day.

 

[clayR]

PEinc,

Yes, point well taken about DOT work....but then again an average price is just a starting place, apart from unbalanced bids many factors must be considered such as size, location, access, degree of risk, soil types, permanent or temporary, and so on.

Initialy, after reading tom's post concerning a unit price for a helical anchor, I felt the need to respond. Based on a 6x6 soil nail spacing, just the cost of the wall for the nails would be over $30/sf of face, not including drains, reinforcement and shotcrete.

I agree with your previous post concerning application of anchor systems, however, I do not think it is a good idea to compare cost of anchor systems and ground nails. cr