Civil Engineering - Irrigation - Discussion

Borrow pits: When earthwork in filling exceeds the earthwork in excavation, the earth has to be brought from somewhere. The pits, which are dug for bringing earth, are known as borrow pits.

If such pits are excavated outside the channel, they are known as external borrow pits, and if they are excavated somewhere within the channel, they are known as internal borrow pits. It is a very costly affair to bring soil from distances. Even in the nearby areas, these pits may cause mosquito nuisance due to a collection of rain water in these pits, and hence, external borrow pits are not preferred.

Basic Concept Of Borrow Pits And It's Design Requirement.

Design Requirements:

The borrow pits should start from a point at a distance more than 5 m from the toe for small channels, and 10 m for large channels.

The width of these pits b should be less than half the width of the canal B, and should be dug in the entire.

The depth of these pits should be equal to or less than 1 m.

Longitudinally, these pits should not run continuous, but a minimum space of L/2 should be left between two consecutive pits, (where L is the length of one pits).

@Bhawana Dubey.

What is water table?

The level below which the ground is saturated with water.

The Water table, also called Groundwater Table, upper level of an underground surface in which the soil or rocks are permanently saturated with water. The water table separates the groundwater zone that lies below it from the capillary fringe, or zone of aeration, that lies above it.

Borrow pits are taken for knowing the liquidity, Plasticity, Permeability, Swell Index and Swell Pressure of Soil.

These are the basic parameters for excavation of canals.

Center half of the canal section may be preferable for borrow pits.

The borrow pit should start from a distance not less than 5 m from the toe of the embankment in the case of small channels and 10 m from the toe in-case of large channels.

Inside borrow pit should have a width not more than half the width.

In construction and civil engineering, a borrow pit, also known as a sand box, is an area where material (usually soil, gravel or sand) has been dug for use at another location.

If we provide borrow pits at the sides of the canal, then WE can't imagine how much water level is around borrowed pits. It means we determine max.

If we provide borrow pit central half width of the section of the canal, then the water coming from the ground water table meets into the canal.

Borrow Pits serves the purpose of depositing silt i.e. running with water. So it is one of the purposes of borrow pit.

Fields on both sides of the canal what happens?

Borrow pits is also known as sand box