You will need excavation if you are building any type of structure, even making roads, laying pipes laying railway lines, or making swimming pools. In this article, we will learn about the cost estimation of earthwork excavation for foundations.
Earthwork can be done either mechanically or manually. Mechanically or using machines, the work can be completed much earlier but manual earthwork is time taking process. Rate analysis of earthwork included the rate of labour and rate of machinery required to complete the task of excavation.
The cost of Excavation depends on the soil, the method of excavation whether manually or through machines, the depth of excavation and the distance up to which the excavated soil needs to be transported for disposing of. It also depends on the labour rates which may vary from place to place.
Earthwork Excavation for Foundation.
Earthwork excavation for a foundation depends on the type of earth that is to be excavated. The soil may be loose or soft, hard rock, soft rock or a mixture of these. The number of labour per day and machinery required per day depends on the earth. We have calculated the earthwork excavation for foundations for all types of soil by mechanical or manual means.
These rates shall be applicable for depth and width not exceeding 1.5 m, 10 sqm on the plan. The rate is including of dressing on the sides and ramming of bottoms. Excavated material can have a lift up to 1.5 m. The excavated soil will be disposed of up to a distance of 50 m from the excavation site.
Let us consider 10 cum of earthwork for which detailed cost will be calculated and by dividing the detailed cost by 10 we will get the cost of 1 cum of earthwork for the foundation.
Rate of Machinery for Earthwork Excavation for Foundation.
Since we are calculating the rate of excavation through machinery, we need to determine the rate of machinery for doing the excavation work. We need an excavator and a loader for excavation work.
An Excavator can excavate 30 cum per hour, thus for a full day, it can excavate 30×8=240 cum of soil.
- 240 cum can be completed in 1 day.
- 1 cum can be completed in 1/240 days.
- 10 cum can be completed in (1/240)x10= 0.041 days.
Similarly, 30cum of per hour can be loaded by the loader.
- 10 cum of soil can be loaded by the loader in 0.041 days.
The rate of excavator and loader per day including fuel and driver charges is different for different places. We have assumed the Excavator rate is 7000 per day and the loader rate is 6000 per day.
Labour charges for Earthwork Excavation for Foundation.
Once we have calculated the rate of machinery and we need to calculate the labour charges for the excavation of earthwork for the foundation. IS 7272 -1974 has laid standard labour productivity for different work for different zones in the country.
We have assumed the labour productivity in the Northern Zone of the country.
- As per IS 7272-1974, for 1 cum of excavation, 0.05 Mate is required. Thus for 10 cum of excavation 0.5 Mate is required.
- For 1 cum of excavation 0.50 Mazdoor is required. Thus 10 cum of Excavation 5.0 Mazdoor will be required if we are excavating using manual methods. Since we are calculating the excavation rate through machinery we will use 2.05 Mazdoor (half) for lifting and transporting the muck.
Other Charges for Earthwork Excavation for Foundation.
Generally, 1% Water charges are required to be paid to the municipality for using the water for construction works. 15% of the total amount obtained after adding 1% water charges is kept as Contractor Profit and Overhead charges for the Contractor.
1-2% of the total amount is paid as Cess to the Govt. as per Regulation of Employment and Conditions of Service) Act, 1996.
After adding all these you will get the cost of excavation of 10 cum of earthwork. For calculating the cost for 1 cum, divide the total by 10 thus you will get the cost of earthwork excavation for the foundation.
Earthwork Excavation for Foundation rate.
Earthwork Excavation rate has been calculated as under:
|Earthwork in excavation by mechanical means (Hydraulic excavator) / manual means in foundation trenches or drains (not exceeding 1.5 m in width or 10 sqm on plan), including dressing of sides and ramming of bottoms, lift up to 1.5 m, including getting out the excavated soil and disposal of surplus excavated soil as directed, within a lead of 50 m.|
|Details of the cost of 10 Cum|
|hydraulic Excavator (3D) with driver and fuel.||day||0.041||7000||287.00|
|Hire and running charges of the loader.||day||0.041||6000||246.00|
|Add 1% water charge||22.16|
|Add 1% cess||25.73|
|Cost of 10 Cum||2599.04|
|Cost of 1 cum||259.90|
Earthwork Excavation Formula
Simple geometrical formulas are used for the calculation of earthwork excavation. For example, you are excavating up to a depth of 1 m and the sides of the pit are of dimension 1m.
- Thus excavation = Length x width x height= 1x1x1 = 1 cum.
This is true for shallow excavation and or soils which can support themselves during excavation. For deeper excavation, we cannot excavate 90 degrees to the ground surface. For such, excavation needs to be done in the slope. This means that the top of the pit will have more area than the bottom of the pit.
- Thus excavation = (Area of the pit at the top +Area of the pit at the bottom )/2 x depth of the pit.
Earthwork Excavation Code
Earth Excavation Work-Code of Safety (IS 3764:1992) is applicable to the earthwork where depth is more than 1.5m and for pits where labour is required to enter the pit. Methods of measurements of various types of earthwork have been laid in IS 1200 Part-I:1992.
Earthwork Excavation cost per m3
Earthwork excavation cost per m3 depends on many factors, like the rate of machinery at particular place, and the rate of labour at a particular place. Generally for soft soil, Rs 200-300 will be required for excavating 1 cum of earthwork for a depth not exceeding 1.5m and lead up to 50 m.
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