Chapter 10

1. Chapter 10 Pricing Excavation and Backfill

2. Objectives • Upon completion of this chapter, you will be able to: • Describe the job factors and the labor and management factors that influence the price of excavation and backfill operations • Use historic productivity rates to calculate the unit price of labor and equipment for excavation and backfill work

3. Objectives (cont’d.) • Calculate the price of gravels and other backfill materials • Calculate trucking requirements for hauling excavated material and gravels • Complete the recap and pricing of excavation and backfill work using manual methods • Use Excel spreadsheets to price excavation and backfill work

4. Excavation Equipment and Methods • Specialized excavation contractors • Concentrate on a single construction type: • Vast array of excavation equipment • Wide scope of work • Common activities: • Site cut and fill operations • Basement-type excavations • Trench excavations • Pit and sump excavations

5. Excavation Equipment and Methods (cont’d.) • Equipment transportation expenses: • Priced on an item-by-item basis • Site cut and fill operations: • Equipment depends on project scale • Basement excavations: • Often performed with a track backhoe • Large basements: one or more track loaders

6. Excavation Equipment and Methods (cont’d.) • Trench excavations: • Smaller trenches: trenching machines • Larger trenches: backhoes • Pit and sump excavations: • Mostly performed using backhoes • Hand excavation: • Rarely used

7. Excavation Productivity • Job factors: • Type of material excavated or backfilled • Moisture condition of materials • Weather conditions expected • Site access and project size/complexity • Distance to haul materials for disposal • Availability of gravels and fill materials • Wage and price levels at the job location

8. Excavation Productivity (cont’d.) • Labor and management factors • Quality of job supervision • Quality of job labor • Motivation and morale of workers • Type and quality of tools and equipment • Experience and records of similar past projects

9. Excavation Work Crews • Labor price per unit of excavation work • Elements to consider: • Number of workers that comprise the work crew and their trades • Wage rates of trades involved • Probable productivity rate of crew or equipment they are operating • Productivity time factor

10. Productivity Rates • Sources: • Provided in publications (e.g., Means Building Construction Cost Data) • Use with caution: general reflect ideal conditions • Also available from manufacturers • May be compiled from contractor’s own projects

11. Figure 10.3 Productivity of Hydraulic Excavators (Delmar/Cengage Learning)

12. Figure 10.4 Sample Data Record (Delmar/Cengage Learning)

13. Excavation Materials • Mostly comprise gravels and fill materials: • Required to meet designer’s specifications • Backfilling • Base courses under slabs and paving • Pricing components: • Supplying material to the site • Spreading and compacting

14. Swell and Compaction Factors • Excavated soil or gravel: • Less dense • Swell factor: • Occupies more volume • Compaction factor: • Allowance for extra material required to fill volumes with compacted material

15. Calculating Trucking Requirements • Determine optimum number of trucks required to transport materials • Formula: • Number of Trucks Required = Unloading Time/ Loading Time + One • Example: Gravel Supply Pricing • Refer to Pages 234 and 235

16. Additional Examples • Excavation and Backfill Recap and Pricing Notes • Example 1—House • Refer to Pages 235 through 240 • Excavation and Backfill Pricing Notes • Example 2—Office/Warehouse Building • Refer to Pages 240 through 244

17. Summary • Many subcontractors perform excavation and backfill work • Most specialize in some aspect • Common methods: • Site cut and fill operations • Basement-type excavations • Trench excavations • Pit and sump excavations