Bridge Lift under compacted fill

[jbird54]

I'm bidding an excavation job on a 7 acre nursing home site. The excavation for the building specifies to undercut the building a total of 7', recompacting 5' with undercut soils and then it specifies to place a 2' bridge lift prior to placing the compacted undercut soils. I'm not sure what the 2' bridge lift is. I'm thinking it is like a 2' clay barrier between uncompacted native material and reapplying the undercut material in 8" lifts. Any help in understanding this is appreciated. It is a 68000 sf building so I need to make sure I know if the 2' bridge lift has to be imported select fill so I plut in enough $$.

Thanks

 

[hokie66]

Why ask us? Ask the specifying engineer.

 

[Ron]

I agree with hokie66...get a clarification from the specifier.

In general, bridge lifts are high modulus materials that spread load across weaker soils. I've used compacted limerock, soil-cement, and cellular concrete fill for this purpose. I would typically not use clay.