Irrigation Infrastructure Enhancement with Ocean Geotextile (PP) 2 MM in Howrah, West Bengal

Ocean Non Wovens supplied 9000 SQM of Ocean Geotextile (PP) 2 MM to an irrigation project in Howrah, West Bengal. The polypropylene non-woven fabric went into the canal and embankment works as a filter, separator and drainage layer.

Project overview

• Project Type: Irrigation Infrastructure Project
• Location: Howrah, West Bengal
• Product Used: Ocean Geotextile (PP) 2 MM
• Quantity: 9000 SQM
• Application Area: Filtration, separation, drainage, and embankment support

The problem with unprotected irrigation works

Irrigation canals and embankments in West Bengal carry water for much of the year. The water moving through and past them slowly carries fine soil into drainage layers and out of embankment faces. Drains silt up, embankments lose material, and maintenance costs rise. Where there is no filter or separation layer between soil and stone or aggregate, this weakening is gradual and hard to spot until a section slumps.

Howrah sits on the alluvial plain of the lower Ganga delta, on the west bank of the Hooghly. Soft, silty alluvium is common there, which makes embankment subgrades weak when wet and easy to erode, so subgrade preparation mattered as much as the fabric.

What the geotextile does

The fabric needed to work under continuous moisture, changing water pressure and variable soil. On this project it performs four jobs:

• Filtration: lets water pass while holding back fine soil particles.
• Separation: keeps aggregate and soil layers from mixing, so the granular layer keeps its thickness and drainage capacity.
• Drainage: relieves water pressure within the embankment.
• Erosion control: stops soil being washed out from beneath protection layers.

Together these keep embankments stable and drainage layers working for longer.

Why filtration matters most

A filter has to strike a balance. If the fabric’s openings are too large, soil migrates through it into the drains and the embankment loses material. If they are too small or the fabric is too dense, sediment builds up on its face and it clogs, which is the most common failure in irrigation drainage. The choice comes down to the apparent opening size (ASTM D4751) relative to the soil grading, and permittivity (ASTM D4491) high enough that water passes more easily through the fabric than through the soil. The Ocean Geotextile (PP) 2 MM was selected because it gave the required balance between permeability and soil retention for this site.

Why polypropylene

Geosynthetics made from polypropylene are common in water works for practical reasons:

• Biological resistance: PP does not rot under constant wetting.
• Chemical resistance: it is not affected by the dissolved salts, fertiliser residues and organic matter typical of irrigation water.
• Hydraulic durability: a needle-punched non-woven keeps its structure under continuous flow and pressure changes.

Its main weakness is ultraviolet light, so the fabric should be covered soon after laying.

Site challenges

Continuous moisture

Unlike most road or industrial jobs, irrigation structures stay wet for long periods, so the fabric has to keep filtering for years without degrading.

Sediment and clogging

Sediment carried by the water can blind a fabric that is poorly matched to the soil. Selecting the right opening size is the main defence.

Soft alluvial soil

Weak subgrade beneath embankments needed proper preparation before the fabric went down.

Installation alignment

Panels must be overlapped correctly and laid without wrinkles. Gaps or folds create weak zones in the filter.

Installation and quality control

The installation sequence on site included:

• Surface grading and preparation
• Removal of sharp protrusions
• Controlled geotextile placement
• Overlap management
• Wrinkle control
• Supervised aggregate placement

Aggregate placement is where fabric is most often damaged: dumping stone or aggregate from height, or driving on uncovered fabric, can tear or displace it. For this reason the project placed aggregate under supervision. Overlaps are usually increased on softer ground, and any torn area should be patched with an overlapping piece before cover goes on.

Long-term performance and maintenance

How long a filter geotextile keeps working depends on soil compatibility, hydraulic loading, installation quality, drainage design and maintenance. Without a filter layer, irrigation systems tend to suffer sediment build-up, blocked drains, weakened embankments and erosion damage. With one, those problems are reduced, and repairs are needed less often. Periodic inspection is still worthwhile to catch local clogging or erosion early.

The same fabric is used in canal lining systems, drainage improvement, embankment works, reservoir containment, riverbank protection and flood control. For more water projects, see Ocean’s case studies.

About Ocean Non Wovens

Ocean Non Wovens supplies geosynthetic products for irrigation, infrastructure, landfill, environmental, industrial and water management projects across India, with manufacturing, supply and project support.