Landfill Project at Delhi – Case Study

Ocean Global supplied the full base lining package for a landfill project in Delhi: an HDPE geomembrane, a polypropylene geotextile and a geosynthetic clay liner (GCL). Together they form a composite liner that keeps leachate out of the soil and groundwater below the waste.

Products: Ocean HDPE Geomembrane-1500 Micron, Ocean Geotextile PP-400 GSM, and Ocean Geosynthetics Clay Liner-5MM

Quantity: 6300 Sqm, 12240 Sqm, and 6058.8 Sqm respectively

Location: Delhi

Problem

Anyone who drives through Delhi-NCR has seen the three garbage mountains at Ghazipur, Bhalswa and Okhla, often with smoke rising from them. These sites have caught fire repeatedly, and some fires have burned for days before they could be put out. Decaying organic waste produces methane, and once a fire starts inside a waste mound it is hard to reach.

The older dumps hold decades of legacy waste with no engineered base. New waste is still added on top every day, so the material underneath cannot be dug out or treated. Mixed in are plastics, e-waste and medical waste, which makes segregation difficult.

The less visible damage is underground. Rainwater percolating through waste becomes leachate, a liquid carrying dissolved organics, salts and metals. Without a liner, it seeps into the soil and groundwater. A new or expanded landfill cell needs a barrier at its base before any waste goes in.

Solution

The project used a composite liner: an HDPE geomembrane laid directly over a geosynthetic clay liner, with a nonwoven geotextile as a cushion and protection layer.

HDPE geomembrane, 1500 micron (1.5 mm). The HDPE geomembrane is the main barrier to leachate. HDPE has very low permeability and good resistance to the chemicals found in leachate. Geomembranes of this type are made from polyethylene resin with 2–3% carbon black for UV resistance, and are supplied with a smooth or textured surface; textured sheets give more friction on side slopes. The 1.5 mm thickness matches the minimum that India’s municipal solid waste rules specify for the geomembrane in a landfill composite barrier. In India, HDPE geomembranes for lining are covered by IS 16352; internationally, GRI-GM13 is the usual reference specification.

Geosynthetic clay liner, 5 mm. A GCL is a thin layer of sodium bentonite held between geotextiles. When wetted, the bentonite swells into a low-permeability seal, with hydraulic conductivity typically in the range of 1×10⁻¹¹ to 5×10⁻¹¹ m/s. Placed under the geomembrane, it backs up the liner: if the HDPE has a small puncture or a faulty seam, the swollen bentonite limits how far leachate can spread through the defect. The Indian rules describe the soil component as 90 cm of clay or amended soil with permeability no higher than 1×10⁻⁷ cm/s; GCLs are commonly proposed as an equivalent where the design is approved.

Geotextile, PP 400 GSM. The nonwoven geotextile protects the geomembrane from puncture by stones in the subgrade and in the drainage gravel placed above it. A 400 GSM fabric is a common choice as a cushion layer in landfill liners.

A typical single composite liner, from the bottom up, is: prepared subgrade, GCL (or compacted clay), HDPE geomembrane, protection geotextile, then a gravel leachate collection layer with pipes that carry leachate to a sump for treatment.

Quantities supplied

To line the landfill, Ocean Global supplied 6300 Sqm of HDPE Geomembrane-1500 Micron, 12240 Sqm of Geotextile PP-400 GSM, and 6058.8 Sqm of Geosynthetics Clay Liner-5MM.

To discuss a landfill or containment lining project, call +91 84472 26007 or see more case studies.