Case Study: Piling & Allied Works in Kamrup, Guwahati – Ocean Non Wovens’ Contribution

For the Piling & Allied Works project under GSCL (Guwahati Smart City Limited) in Kamrup, Guwahati, Ocean Non Wovens supplied 1000 Sqm of 13mm Drain Board. The boards were installed next to the piling structures to give water collecting around the foundations a clear path out, keeping the surrounding soil from softening and limiting water pressure against the structures.

Piling and allied works

Where the near-surface soil cannot carry a structure’s load, piles transfer it down to stronger strata. Piles are columns of concrete, steel or timber, either driven or bored and cast in place; in urban work like GSCL’s, bored cast-in-situ concrete piles are common because they cause less vibration. They support buildings, bridges and flyovers.

“Allied works” covers the activities around the piling: excavation, retaining wall construction and ground improvement, so that the foundations can resist groundwater pressure and seismic loading. Guwahati lies in seismic zone V under IS 1893, the highest category in India.

Site challenges in Kamrup

Guwahati sits on the south bank of the Brahmaputra and receives heavy monsoon rainfall, around 1,700 mm a year. The water table rises and falls with the seasons, and the soils erode easily. Water collecting around piling zones and pile caps softens the soil, can lead to settlement, and pushes against walls and below-ground concrete. Drainage during and after construction keeps the ground workable and stable.

What a drain board does

A drain board is a dimpled or studded core, usually high-density polyethylene (HDPE), faced with a non-woven filter fabric. The dimples hold the fabric off the structure and form a continuous channel behind it. Water passes through the fabric into the channel and runs down to a collector drain, while the fabric keeps soil particles out. The 13mm figure is the height of the core.

On the GSCL site, the boards placed beside the piling structures intercept seepage from the surrounding soil, which reduces hydrostatic pressure on the structures and stops water from washing out fine soil around them.

Benefits of the 13mm drain board

1. Soil stability: water does not pond around the piling zones, so the soil stays compacted instead of loosening.
2. Durability of structures: controlling groundwater movement reduces water-related damage to structures on piles.
3. Less erosion: a controlled flow path keeps water from carrying away fine particles, which helps prevent loss of soil and subsidence around the foundations.
4. Cost: good drainage reduces the need for dewatering and additional soil stabilization.

Drain boards tend to get less attention than the piles and walls they protect, but on a site with a high, fluctuating water table, managing subsurface water is part of keeping those foundations in shape.

Installation

1. Preparation of Substratum: the soil around the piling area was levelled.
2. Placement of Drain Boards: boards were placed with the filter fabric facing the soil, so water enters the core and soil stays out.
3. Overlay with Geotextiles: the boards were overlaid with geotextile for an extra filtration layer against clogging.
4. Inspection and Testing: water flow tests after installation confirmed the drainage was working.

In typical practice, adjacent boards are overlapped by at least one row of dimples, the fabric flap is lapped over the joint so backfill cannot enter the core, and the base of the board discharges into a perforated collector pipe or weep system. With the boards in place, the construction team could manage water flow on site and avoid water-related delays.

About Ocean Non Wovens

Ocean Non Wovens manufactures and supplies geosynthetics, including drain boards, geotextiles and related products, and provides on-site support so materials are used correctly. For drainage behind walls, around foundations or below slabs, contact the team with your site details.