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Homework 9&10 Construction Estimating I (California State Polytechnic University Pomona) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Homework 9&10 Construction Estimating I (California State Polytechnic University Pomona) Scan to open on Studocu Studocu is not sponsored or endorsed by any college or university Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
Chapter 9 1 Excavation Chapter 9—Excavation LEARNING OBJECTIVES Learn how to demine excavation quantities using the cross-sectional method, the average-end-area method, and the average width and length; and when to use each method. Explain how shrink and swell affect the volume of earthen materials that need to be excavated, hauled, and compacted. Learn how to estimate the quantities of landscaping, granular base, and asphalt. Learn how to determine the cost of each of these items. HOMEWORK QUESTIONS 1. What type of information about the excavation can the estimator learn from the specifications? The extent of work, excess excavated material, the persons who responsible on clearing, grubbing, trees, and trenching. 2. How does the type of soil to be excavated affect the estimate? The estimator should investigate the soil conditions at the job site, and also need to check the drawings and the specifications of the project. 3. What is the unit of measure in excavation? The unit of measure in excavation is cubic yard. 4. How will the type of soil, shape of the excavation, and amount of work to be done affect the equipment selection? Different phase of excavation requires different equipments. For instances, if material must be hauled some distances, then the excavated material should be hauled out or the fill material hauled in, such as trucks or tractor-pulled wagons. 5. What is the difference between a bank cubic yard, a loose cubic yard, and a compacted cubic yard? Why are they important in estimating excavation? Bank cubic yards is the material in its natural state. The loose cubic yards are the uncompacted excavated materials. The compacted cubic yards are the compacted materials. They are important because as estimator, it is essential to understand the swell and shrinkage factors for various types of soils. 6. What is meant by cut and fill? Cutting means to bring the ground to a lower level by removing earth. Filling means to bring soil in to build the land to a higher elevation. 7. What does the estimator have to consider if there is a substantial amount of cut on the job? What if there is a substantial amount of fill? The estimator needs quantities to estimate the amount of effort required to convert the cut material into the fill material. If there is a substantial amount of fill, then it must be hauled to where it will be used and then compacted. 8. How can the estimator get an estimate of the depth of topsoil on the project? The estimator needs to determine the depth of the topsoil, where it will be stockpiled, and what equipment should be used to strip the topsoil and move it Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
Chapter 9 2 Excavation to the stockpile area. 9. What type of excavation is considered to be general excavation? It is the removal of all types of soil that can be handled in fairly large quantities, and it is required for basement, mat footing, or a cut for a highway or parking area. 10. How does general excavation differ from special excavation? The special excavation is the portion of the work that requires hand excavation, and requires special equipment to be used for a particular portion. Most of the work includes footing holes, small trenches, and the trench-out areas. 11. What is excess and borrow, and how are each considered in the estimate? It the determination on whether there will be an excess of materials that must be discarded, or whether there is a shortage of materials and some must be brought in. The estimator needs to know how many cubic yards are required, and then the estimator must find a place to haul the material. The equipments are also need to be considered. 12. How will the possibility of a high water table or underground stream affect the bid? It depends on the projects; some projects require constant pumping to keep the excavation dry, and the variation in costs is extreme. Also the problem of water will depend the season of the year, location, type of work, general topography, and weather. 13. What are piles, and under what conditions might they be required on the project? Piles are used to support loads are referred to as bearing piles. The conditions of use might be depended on the types of soil, and depth to be driven make accurate cost details difficult to determine unless the details of each particular job are known. 14. For a project, your company needs to haul away 1,450 bank cubic yards (bcy) of soil. If the soil has a swell of 25 percent, how many loose cubic yards (lcy) of soil will need to be hauled? How many truckloads are required to haul the soil offsite if each truck can haul nine loose cubic yards? Cubic yards of haul = 1,450 x (1 + 0.25) = 1812.5 lcy Loads = 1812.5 / 9 = 202 loads 15. For a project, your company needs to haul away 350 bank cubic yards of sand. If the sand has a swell of 12 percent, how many loose cubic yards of sand will need to be hauled? How many truckloads are required to haul the sand offsite if each truck can haul 12 loose cubic yards? Cubic yards of haul = 350 x (1 + 0.12) = 392 lcy Loads = 392/12 = 33 loads 16. If 750 compacted cubic yards (ccy) of in-place soil is required for a project, how many loads of import will be required? The import material has a swell of 30 percent and shrinkage of 90 percent. The trucks can haul 10 loose cubic yards. Required bcy = 500/0.9 = 556 bcy Loose cubic yards = 556 x (1 + 0.3) = 573 lcy Loads = 573 / 10 = 58 loads Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
Chapter 9 3 Excavation 17. If 1,490 compacted cubic yards of in-place soil is required for a project, how many loads of import will be required? The import material has a swell of 14 percent and shrinkage of 95 percent. The trucks can haul 12 loose cubic yards. Determine the volume of the haul and the number of loads as follows: Required bcy = 1,490 / 0.95 = 1569 bcy Loose cubic yards = 1569 bcy x (1 + 0.14) = 1789 lcy Loads = 1789 / 12 = 149 loads 18. Using the cross-sectional method, determine the cuts and fill for the project shown in Figure 9.47. The grids are 50 feet apart in both directions. The existing grade appears above the proposed grade. Express your cuts in bank cubic yards (bcy) and your fills in compacted cubic yards (ccy). The cuts and fills are shown in Figure 9-1. Figure 9-1 Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
Chapter 9 4 Excavation The dividing line between the cuts and fills and the distances from the grid intersections to this line are shown in Figure 9-2. Figure 9-2 Unless the division line between the cuts and fills passes through a cell, the cut or fill area is 2,500 square feet (50 ft × 50 ft). The cuts and fills are as follows: Cell 1: Cut 1 = (0 ′ + 0 ′ + 0 ′ + 0.1 ′) / 4 × 2,500 sf = 62 bcf Fill 1 = 0 ccf Cell 2: Cut 2 = (0 ′ + 0 ′ + 0.1 ′ + 0.3 ′) / 4 × 2,500 sf = 250 bcf Fill 2 = 0 ccf Cell 3: Cut 3 = (0 ′ + 0 ′ + 0.3 ′ + 0.9 ′) / 4 × 2,500 sf = 750 bcf Fill 3 = 0 ccf Cell 4: Cut 4 = (0 ′ + 0 ′ + 0.9 ′ + 1.1 ′) / 4 × 2,500 sf = 1,250 bcf Fill 4 = 0 ccf Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
Chapter 9 5 Excavation Cell 5: Cut 5 = (0 ′ + 0 ′ + 1.1 ′ + 1.5 ′) / 4 × 2,500 sf = 1,625 bcf Fill 5 = 0 ccf Cell 6: Cut 6 = (0 ′ + 0 ′ + 1.5 ′ + 0 ′) / 4 × 2,500 sf = 938 bcf Fill 6 = 0 ccf Cell 7: Cut Area 7 = (12.5 ′ × 50 ′) / 2 = 312 sf Cut 7 = (0 ′ + 0 ′ + 0.1 ′) / 3 × 312 sf = 10 bcf Fill Area 7 = (37.5 ′ × 50 ′) / 2 = 938 sf Fill 7 = (0 ′ + 0 ′ + 0.3 ′) / 3 × 938 sf = 94 ccf Cell 8: Cut Area 8 = (50 ′ × 50 ′) – (37.5 ′ × 30 ′) / 2 = 1,938 sf Cut 8 = (0.1 ′ + 0.3 ′ + 0 ′ + 0 ′ + 0.2 ′) / 5 × 1,938 sf = 233 bcf Fill Area 8 = (37.5 ′ × 30 ′) / 2 = 562 sf Fill 8 = (0 ′ + 0.3 ′ + 0 ′) / 3 × 562 sf = 56 ccf Cell 9: Cut 9 = (0.3 ′ + 0.9 ′ + 0.2 ′ + 0.4 ′) / 4 × 2,500 sf = 1,125 bcf Fill 9 = 0 ccf Cell 10: Cut 10 = (0.9 ′ + 1.1 ′ + 0.4 ′ + 0.7 ′) / 4 × 2,500 sf = 1,937 bcf Fill 10 = 0 ccf Cell 11: Cut 11 = (1.1 ′ + 1.5 ′ + 0.7 ′ + 0.9 ′) / 4 × 2,500 sf = 2,625 bcf Fill 11 = 0 ccf Cell 12: Cut 12 = (1.5 ′ + 0 ′ + 0.9 ′ + 0 ′) / 4 × 2,500 sf = 1,500 bcf Downloaded by Sivasankar Marisetty (w968b46bzj@privaterelay.appleid.com) lOMoARcPSD|37363189
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