How Long Does It Take To Dig a 6 Foot Hole? Production Rates For Manual and Mechanical Excavation in Light, Medium and Heavy Soil

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How Long Does It Take To Dig a 6 Foot Hole? Production Rates For Manual and Mechanical Excavation in Clay, Sand, Silt, Loam, Silty Sand, Silty Clay and Sandy Clay.

How long it takes to dig a hole depends on the production rate or excavation rate in this case, and the production rate for construction work depends on a variety of factors which are going to be discussed below.

A 6 foot hole is roughly 1.83 metres deep in metric units. This is a very deep hole that would require earthwork support and means of access in and out of the hole. To give you an idea of how deep this hole is, the average height of human beings around the world ranges from 5 foot (152cm) to (6.10 foot (185.6cm). How long it takes to dig a hole of this nature depends not just on its height, but on its width or diameter as well. More importantly, you have to consider other factors such as the ground conditions. The rates for digging in different types of soils are not the same. It’s much easier, quicker and cheaper to dig in light soil such as silty sand, loess or loam. Digging in medium soil such as sandy clay will slightly reduce the production output rate and increase the labour cost. Digging in heavy soils such as clay, shale and caliche will reduce the production output rate further, and increase costs. Heavy soils are the most expensive soil type to dig in if we are not taking rock into consideration, otherwise ground with loose and hard rock is the most expensive.

Heavy soils are cohesive soils with a high amount of fine particles (clay). They tend to be hard when dry and plastic when moist. Light soils are granular soils like sand and silt with a small amount or absence of clay. As a result, they lack cohesive strength, which makes them easier to dig in than cohesive soils.

How long it takes to dig a hole also depends on the type of digging equipment used. Obviously, a labourer using a power digging tool like a tractor-mounted auger will make progress much more quickly than a labourer using a pick, shovel and clamshovel to dig a 6 foot hole.

Chart – Production Rates for Digging Holes and Trenches in Light, Medium and Heavy Soil

Calculations – How Long It Takes To Dig a 6 Foot Hole [ Manual Excavation Using a Pick and Shovel ]

Shown below are calculations for excavation production outputs for digging a 6 foot deep traditional grave and stormwater drywell using hand tools (pick, shovel, clamshovel etc.) in different types of soils.

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1 – How Long Does It Take to Dig a 6 Foot Grave using Manual Labour and Hand Tools?

Calculations:

Assuming the standard size of a grave is 30 inches wide x 7.2 feet long x 6 feet deep, you will need to excavate 2.5 x 7.2 x 6 ft = 108 cf of soil.

Digging in Light Soil:

Volume of excavated soil:  V = 2.5 x 7.2 x 6 ft = 108 cf.

Manual excavation standard output rate for excavating in light soil for trenches 4 to 6 feet deep:  0.68 cy per hour.

Converting CF to CY: 108 cf = 4 cy.

0.68 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/0.68 = 5.8 hours. It takes 5.8 hours to dig 4 cubic yards of earth in light soil (sand, silt, loess, etc.)

Digging in Medium Soil:

Manual excavation standard output rate for excavating in medium soil for trenches 4 to 6 feet deep:  0.54 cy per hour.

0.54 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/0.54 = 7.41 hours. It takes 7.41 hours to dig 4 cubic yards of earth in medium soil (sandy clay, loam, silty clay, silty clay loam and sandy clay loam etc).

Digging in Heavy Soil:

Manual excavation standard output rate for excavating in heavy soil for trenches 4 to 6 feet deep:  0.46 cy per hour.

0.46 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/0.46 = 8.70 hours. It takes 8.70 hours to dig 4 cubic yards of earth in heavy soil (clay, shale, caliche, etc).

2 – How Long Does It Take to Dig a 6 Foot Deep Hole for Stormwater Drywell using Manual Labour and Hand Tools?

Calculations:

Drywell Hole Size:  450 x 450 x 1830mm Deep [1.5 x 1.5 x 6 Foot Deep]

We are going to estimate how long it takes to dig a square hole that is 1.5 ft wide x 6 ft deep.

Excavation in Light Soil:

Volume of excavated soil, V = 1.5 x 1.5 x 6ft = 13.50 cf

Manual excavation standard output rate for excavating in light soil for trenches 4 to 6 feet deep:  0.68 cy per hour.

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Converting CF to CY: 13.50 cf = 0.50 cy

0.68 cy = 1 hour

0.50 cy = Less

Therefore, (0.50 x 1)/0.68 = 0.74 hours. It takes 0.61 hours (44 minutes) to dig 0.50 cubic yards of earth in light soil (sand, silt, loess, etc).

Excavation in Medium Soil:

Volume of excavated soil, V = 1.5 x 1.5 x 6ft = 13.50 cf

Manual excavation standard output rate for excavating in medium soil for trenches 4 to 6 feet deep:  0.54 cy per hour.

Converting CF to CY: 13.50 cf = 0.50 cy

0.54 cy = 1 hour

0.50 cy = Less

Therefore, (0.50 x 1)/0.54 = 0.93 hours. It takes 0.93 hours  (56 minutes) to dig 0.50 cubic yards of earth in medium soil (sandy clay, loam, silty clay, silty clay loam and sandy clay loam etc).

Excavation in Heavy Soil:

Volume of excavated soil, V = 1.5 x 1.5 x 6ft = 13.50 cf

Manual excavation standard output rate for excavating in light soil for trenches 4 to 6 feet deep:  0.46 cy per hour.

Converting CF to CY: 13.50 cf = 0.50 cy

0.46 cy = 1 hour

0.50 cy = Less

Therefore, (0.50 x 1)/0.46 = 1.09 hours. It takes 1.09 hours to dig 0.50 cubic yards of earth in heavy soil (clay, shale, caliche, etc).

 

Calculations – How Long It Takes To Dig a 6 Foot Hole [ Mechanical Excavation Using Heavy Machinery or Power Tools ]

Shown below are calculations for excavation production outputs for digging a 6 foot deep traditional grave and stormwater drywell using mechanized equipment in different types of soils.

1 – How Long Does It Take to Dig a 6 Foot Deep Grave using Mechanized Equipment?

Calculations:

We are going to use a backhoe with operator, one labourer and ¾ CY bucket. Assuming the standard size of a grave is 30 inches wide x 7.2 feet long x 6 feet deep, you will need to excavate 2.5 x 7.2 x 6 ft = 108 cf of soil.

Digging in Light Soil:

Volume of excavated soil:  V = 2.5 x 7.2 x 6 ft = 108 cf.

Mechanical excavation (Backhoe with operator, one labourer and ¾ CY bucket) standard output rate for excavating in light soil for trenches 4 to 6 feet deep:  13.2 cy per hour.

Converting CF to CY: 108 cf = 4 cy.

13.2 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/13.2 = 0.30 hours. It takes 0.30 hours (18 minutes) to dig 4 cubic yards of earth in light soil (sand, silt, loess, etc.)

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Digging in Sand:

Volume of excavated soil:  V = 2.5 x 7.2 x 6 ft = 108 cf.

Mechanical excavation (Backhoe with operator, one labourer and ¾ CY bucket) standard output rate for excavating in light soil for trenches 4 to 6 feet deep:  16 cy per hour.

Converting CF to CY: 108 cf = 4 cy.

16 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/16 = 0.30 hours. It takes 0.25 hours (15 minutes) to dig 4 cubic yards of earth in sand.

Digging in Medium Soil:

Mechanical excavation (Backhoe with operator, one labourer and ¾ CY bucket) standard output rate for excavating in medium soil for trenches 4 to 6 feet deep:  12.5 cy per hour.

12.5 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/12.50 = 0.32 hours. It takes 0.32 hours (19.2 minutes) to dig 4 cubic yards of earth in medium soil (sandy clay, loam, silty clay, silty clay loam and sandy clay loam etc).

Digging in Heavy Soil:

Mechanical excavation (Backhoe with operator, one labourer and ¾ CY bucket) standard output rate for excavating in heavy soil for trenches 4 to 6 feet deep:  10.3 cy per hour.

10.3 cy = 1 hour,

4 cy = More,

Therefore, (4 x 1)/10.3 = 0.39 hours. It takes 0.39 hours (23.3 minutes) to dig 4 cubic yards of earth in heavy soil (clay, shale, caliche, etc).

1 – How Long Does It Take to Dig a 6 Foot Deep Stormwater Drywell using Mechanized Equipment?

We are going to estimate how long it takes to dig a 16 inch diameter x 6 ft deep hole using a truck-mounted A-frame hoist and power operated auger.

Drywell hole size:  1.33 ft diameter x 6 foot deep.

Volume of cylinder:  V = πr²h

V = π (1.33)² x 6

V = 33.34 cf

Excavation in Stable Soil:

Volume of excavated soil, V = 33.34 cf

Converting CF to CY: 33.34 cf = 1.23 cy.

Mechanical excavation (Truck-mounted A-frame hoist and power operated auger) standard output rate for digging in stable soil for holes:  680 VLF per day (VLF stands for Vertical Linear Foot in Construction).

680 vlf = 1 day (8-hour day)

6 vlf = Less

Therefore, (6 x 8)/680 = 0.07 hours. It takes 0.07 hours (4.24 minutes) to dig 1.23 cubic yards of earth in stable soil. This means it takes 4.24 minutes to dig a 6 foot deep hole of 16 inches diameter.


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