Engineering and Construction

      a. On the basis of tentative designs, the cost of each promising alternative should be estimated.
Estimate sheets should show orderly entries of items, dimensions, quantities, unit material and labor costs, and cost extensions.  Use local labor and material costs.

      b. The preliminary foundation designs that are compared must be sufficiently completed to include all
relevant aspects.  For example,  the increased cost of piling may be partially offset by pile caps that are smaller and less costly than spread footings.  Similarly, mat or pile foundations may require less excavation.

Foundation dewatering during construction may be a large item that is significantly different for some foundation alternatives.

      c. The most appropriate type of foundation generally represents a compromise between
performance, construction cost, design cost, and time.

Of these, design cost is generally the least important and should not be permitted to be a controlling factor.  If a lower construction cost can be achieved by an alternative that is more expensive to design, construction cost should generally govern.

      d. Foundation soils pretreatment by precompression under temporary surcharge fill, regardless of whether vertical sand drains are provided to accelerate consolidation, requires a surcharge loading period of about 6 months to a year.  The time required may not be available unless early planning studies recognized the possible foundation cost reduction that may be achieved.  Precompression is frequently advantageous for warehouses and one-story structures.

Precompression design should be covered as a separate design feature and not considered inherent in structure design.