1. Estimating Ahmed Elyamany, PhD, AVS

2. EARTHWORK AND EXCAVATION bank  Earth that is to be excavated is called bank measure. loose  Earth that is to be hauled is called loose measure. compact  Earth that is to be compacted is called compact measure.  Earth after being loosened during excavation and placed in the hauling unit will increase in volume and called swell.  When the earth is placed in a fill area and compacted with compaction equipment, it decrease in volume and called shrinkage.

3. EARTHWORK AND EXCAVATION  The correlation between volume, swell, and shrinkage are shown in the following equations:  L = {1 + Sw/100}B  C = {1 – Sh/100}B  where  L = volume of loose soil  B = volume of undisturbed soil  C = volume of compacted soil  Sw = percentage of swell  Sh = percentage of shrinkage

4. EARTHWORK AND EXCAVATION  Range of swell factors for some materials:

5. EARTHWORK AND EXCAVATION Example  Clay soil with a bank unit weight of 1.7 ton/m3 is excavated, hauled by 17 m3 (loose measure) trucks, and placed in a fill and compacted.  The empty weight of the truck is 30.6 ton.  The swell factor and shrinkage factor respectively are 30 and 15 percent.  Calculate the following:  1. Equivalent bank measure volume and compacted measure volume for the 17 m3 truck load of soil, and  2. The total vertical weight of the hauling unit with the pay load of the soil.

6. EARTHWORK AND EXCAVATION Solution  Equivalent loose measure volume: L = (1+ Sw/100)B  17 m3= (1 + 30/100)B  B = 17/(1 + 0.30) = 22/1.3 = 13.08 m3 bank volume.  C = (1 ‐ Sh/100)B = {1 ‐ (15/100)} 13.08 = 15.04 cy compacted volume  Weight of soil pay load, L1 = B1/{1+(Sw/100)}  = 1.7/{1+(30/100)}  = 1.7/1.3 = 1.31 ton/m3 loose weight of soil  Soil pay load = 1.31 x 17= 22.23 ton  Empty weight of truck = 30.6ton  Total weight with pay load = 30.6 + 22.23= 52.83 ton

7. Excavating by hand  Numerous types and sizes of excavating equipment is generally used in construction except in very small projects where using equipment will be more expensive.  Even if the job is big, sometimes there may not be sufficient room to operate the equipment such as for a motor ‐ pump foundation for a unit located in a confined space in a refinery.  Also, if numerous underground utilities exist, it may be difficult to use equipment and so, under these circumstances, manual excavation has to be resorted to.

8. Excavating by hand Operation Cy/hrHr/cy Excavating Sandy loam 1.0-2.00.5-1.0 Loosing earth with a pick 0.25-0.52.0-4.0 Shoveling loose earth into a truck 0.5-1.01.0-2.0 Shoveling from trenches 0.5-1.01.0-2.0 Backfilling earth into trenches 1.5-2.50.4-0.7 Spreading loose earth 4.0-7.00.15-0.25

9. Excavating by hand Example  A trench in a confined area in a refinery has to be excavated by hand.  The trench is 15 ft long, 3 ft wide and 4 ft deep and the soil is sandy loam.  Calculate the cost of excavation. Cost of labor is $15.56/hr.

10. Excavating by hand Example …Solution:  Quantity of work:  Volume of earth = (3 x 4 x 15)/27 = 6.7cy  Production rate:  Using Table VI.1:  Loosening earth with a pick = 6.7 x 2 hrs/cy = 13.4 hrs  Shoveling loose earth into a truck = 6.7 x 1 hr/cy= 6.7 hrs  Total labor hours = 20.1 hrs  Cost:  Total cost = 20.1 hrs x $15.56 = $312.756  Cost/cy = $312.756/6.7 = $46.68

11. Excavating by machine  For larger jobs, the cost of excavation by machine is considerably less than the cost by hand once the machine is transported to the job site.  The savings in excavating cost must be sufficient to offset the cost of transporting the machine to the job and back to storage after the job is completed.  Otherwise, hand labor is more economical.

12. Trenching machines  There are two types of trenching machines:  (1) Wheel ‐ type and  (2) Ladder-type.

13. Trenching machines Wheel ‐ type machine  Wheel ‐ type machine is frequently used for water mains, gas lines, and oil pipe lines.  The wheel rotates at the rear of the machine, which is mounted on crawler tracks.  A combination of teeth and buckets attached to the wheel loosens and removes the earth from the trench as the machine advances.  The machine can be used to excavate trenches 16-20 in. wide and depths up to 6 ft.  Table VI.4 provides data on this type of machines.

14. Trenching machines Wheel ‐ type machine Depth of trench (ft) Width of trench (in) Digging speed (ft/hr) 2-4 16, 18, 20150-400 22, 24, 2690-300 28, 3060-180 4-6 16, 18, 2040-120 22, 24, 2625-90 28, 3015-40

15. Trenching machines Ladder ‐ type machine  Ladder ‐ type machine is used for deeper trenches such as those required for sewer pipes and other utilities.  Inclined or vertical booms are mounted at the rear of the machine.  Cutter teeth and buckets are attached to endless chains that travel along the boom.  The depth of cut is adjusted by raising or lowering the boom.  By adding side cutters, the width of the trench can be increased.  This machine is used to excavate trenches from 16-36 in. wide and depths up to 12 ft.

16. Trenching machines Ladder ‐ type machine  Table VI.5 provides data on this type of machines. Depth of trench (ft) Width of trench (in) Digging speed (ft/hr) 4-6 16, 20, 22100-300 24, 26, 2875-200 30, 32, 3640-125 6-8 16, 20, 2240-125 24, 26, 2830-60 30, 32, 3625-50 8-12 18, 24, 3030-75 32, 24, 3014-40

17. Trenching machines Example:  Estimate the total cost and cost/linear foot for excavating 2,940 ft of trench in common earth using a ladder ‐ type trenching machine.  The trench will be 30 in. wide and the average depth will be 7 ft.  The machine will work for 45 min. in an hour.  A machine operator, a laborer and a foreman will be employed on the job with a pickup truck.  The rate for trenching machine is $87.50/hr.  The machine operator is paid at $21.67/hr, the laborer is paid at $25.56/hr and the foreman is paid at $25.00/hr.  The rate for pickup truck is $12.00/hr.  In addition, transporting the machine to and from the job cost a lump sum of $1,500.00

18. Trenching machines Example….. Solution:  From Table the digging speed is found to vary between 25 and 50 ft/hr for a width of 30 in and depth of 7 ft.  Use the average digging speed of 37.5 ft/hr.  Time for digging trench = 2,940/37.5 = 78.4 hrs  Adjusting for 45 min/hr, time required = 78.4 x (60/45) = 104.5 hrs

19. Trenching machines Example….. Solution:  Cost:  Trenching machine : 104.5 hrs @ $87.50/hr = $9,143.75  Machine operator 104.5 hrs @ $21.67 = 2,264.50  Laborer 104.5 hrs @ $15.56 = 1,626.02  Foreman 104.5 hrs @ $25.00 = 2,612.50  Pickup truck 104.5 hrs @ $12.00 = 1,254.00  Transporting machine to and from job = 1,500.00  Total cost = $18,400.77  Cost/linear foot = $18,400.77/2,940 = $6.26

20. FOUNDATIONS  Foundations that support structures include footings, piles, and drilled shafts.  Footings are shallow while piles and drilled shafts are deep.  Footings are placed at shallow depths, usually less than 5ft.  Footings may be isolated or continuous.  Isolated footings are placed at one location to support a column.  Continuous footing provides support for a wall of a building.

21. FOUNDATIONS  Construction of a footing includes excavating the soil to the required depth, erecting formwork, setting reinforcing steel, placing concrete, removing formwork, and backfilling soil above the footing to the surface of the ground.  A trench is excavated into the soil to construct a continuous footing. If the sides of the excavated soil are stable enough to support itself without caving in, there is no need for providing formwork.

22. FOUNDATIONS  If the soil is unstable, it will be necessary to install a system of shores, braces, and solid sheeting along the excavated walls to hold the earth in position.  Sheeting is typically constructed with 2,3 or 4 ‐ in thick lumber, placed side by side or overlapping along the whole length of the trench.  Wales consisting of 4 x 6 ‐ in thick lumber can be placed in a horizontal direction to provide additional support for the sheeting.  Depending upon the stability of the earth, it may be necessary to install braces at suitable intervals.

23. FOUNDATIONS Example  Estimate the cost of installing and removing solid sheeting and bracing for a trench 100 ft long and 7 ft deep.  The sheeting will be 2 x 12 ‐ in lumber, 8 ft long.  Two horizontal rows of 4 x 6 ‐ in wales will be placed on each side of the trench for the full length of the trench.  Trench braces is placed 4 ft apart along each row of wales.  The sheeting will be driven one plank at a time by using an air compressor and a pneumatic hammer.  bf : board-foot is a specialized unit of measure for the volume of lumber in USA

24. FOUNDATIONS Example  Two laborers combined will install the sheeting at 4/hr and wales and braces at 3/hr.  The following material cost will apply:  sheeting $0.73/bf,  wales $0.92/bf,  braces $3.50 each.  The following equipment cost will apply:  air compressor $8.75/hr  air hammer $1.75/hr.  Labor costs are $21.67/hr for driving sheet piles and $18.17 for installing wales and braces.  Estimate the cost of installing and removing solid sheeting and bracing

25. FOUNDATIONS Example …. Solution:  Quantity of materials:  Sheeting, using actual dimension of 2 x 12 lumber as 1.5 in x 11.25 in  Number of pieces for two sides= 100/(11.25/12) x 2 = 214 pieces.  Quantity of sheeting = 214 x 2 x (12/12) x 8 = 3,424 bf

26. FOUNDATIONS Example …. Solution:  Quantity of materials:  Wales: Number of pieces for one row = 100/8=12.5, use 13 pieces =  Quantity of lumber = (13x2x2) x 4 x (6/12) x 8 = 832 bf  Trench braces = (100/4) x 2= 50  Time to perform the job:  2 laborers installing sheeting = 214/4 = 53.5 hrs  2 laborers installing wales and braces = (50 + 13)/3 = 21 hrs

27. FOUNDATIONS Example…..Solution:  Labor cost:  Laborers driving piles 53.5 hrs x 2 x $21.67 = $2,318.69  Laborers installing wales and braces = 21hrs x 2 x $18.17 = $763.14  Total labor cost = $3,081.83

28. FOUNDATIONS Example…..Solution:  Material cost:  Sheeting 3,424 bf @ $0.73 = $2,499.52  Wales 832 bf @ $0.92 = 765.44  Braces 50 @ $3.50 = 175.00  Total material cost = $3,439.96

29. FOUNDATIONS Example…..Solution:  Equipment cost:  Air compressor 53.5 hrs x $8.75 = $468.13  Air hammer, hose etc 53.5 hrs x $1.75 = 93.63  Total equipment cost = $561.76

30. FOUNDATIONS Example…..Solution:  Summary of costs:  Labor = 3,081.83  Material = 3,439.96  Equipment = 561.76  Total cost = $7,083.55  Cost/linear foot of trench = $7,083.55/100 = $70.84  Cost/sf of sheeting = $7,083.55/(100 x 7 x 2) = $5.06

31. Thanks