Construction Cost Estimate Assignment

A land developer plans to build a new building on a site that has marginal soil conditions. The geotechnical engineer has identified two alternative foundation systems for this proposed building:

Alternative 1: Support the building on pile foundations that extend through the marginal soils into the deeper stronger soils.

Alternative 2: Excavate the upper 10 feet of soil and replace it as a compacted fill. The proposed building may then be supported on spread footing foundations founded on the compacted fill.

Both alternatives will use a slab-on-grade floor. In addition, both alternatives will produce a foundation system with equal quality and reliability, and the construction time will be about the same. Neither will require any future maintenance. Thus, the only consideration in selecting the final design is the respective cost of the foundation construction.

The structural engineer developed preliminary design drawings for both alternatives, and these drawings show the following:

• The proposed building will be rectangular with plan dimensions of 150 ft by 200 ft. It will have 35 interior columns and all of the perimeter walls will be bearing walls.

• For Alternative 1, each column will require four piles, each of which must be 25 ft long. In addition, each column will require a 5x5x3 ft reinforced concrete pile cap. The exterior bearing walls will require 25 ft long piles at 10 ft on center, and a 2x2 ft reinforced grade beam along the base of the wall.

• For Alternative 2, each column will require a 10x10x3 ft reinforced concrete spread footing, and the exterior bearing walls will require a 3x2 ft reinforced concrete continuous spread footing.

The civil engineer developed a preliminary site plan and grading plan. For Alternative 2, the excavation and recompaction will extend 10 ft beyond the building footprint, as recommended by the geotechnical engineer. The civil engineer also determined that Alternative 2 will require 1800 cubic yards of import fill to make up for the shrinkage that will occur during the excavation and recompaction process.

Develop hand-drawn sketches of each alternative showing the relevant items needed to develop the cost estimate. Include relevant dimensions.

The unit cost information is as follows: Excavation and recompaction Materials $0

Equipment and labor $5.00 / yd³

Overhead and profit 10% of the materials, labor, and equipment costs

Import fill

Materials $20.00 / yd³

Equipment and labor $4.00 / yd³

Overhead and profit 10% of the materials, labor, and equipment costs

Pile foundations
Materials $27.00 / ft
Equipment and labor $9.50 / ft
Overhead and profit 10% of the materials, labor, and equipment costs

Reinforced concrete for pile caps and grade beams; includes excavation costs Materials $180.00 / yd3
Equipment and labor $230.00 / yd3
Overhead and profit 10% of the materials, labor, and equipment costs

Reinforced concrete for footings; includes excavation costs Materials $150.00 / yd3
Equipment and labor $200.00 / yd3
Overhead and profit 10% of the materials, labor, and equipment costs

Compute the construction quantity take offs and develop construction cost estimates for both alternatives.

Based on the results of this analysis, recommend a course of action.

Your submittal should include:

• A cover sheet with the course name, the name of the assignment, your name, the submittal date, and any other information you deem to be relevant

• The hand-drawn sketches of each alternative

• Your quantity take offs and cost estimates presented as shown above with the relevant hand and/or spreadsheet calculations as needed.

• Short statement of your recommended course of action