Ocean HDPE Liner 1.8 mm and 2 mm for an NTPC Project at Badarpur, Delhi

Ocean Non Wovens supplied 25,000 sq m of heavy-gauge Ocean HDPE Liner to NS Infra Projects for an NTPC project at Badarpur, Delhi: 5,000 sq m of 2 mm sheet and 20,000 sq m of 1.8 mm sheet. What follows describes the site first, then what HDPE liner at 1.8 mm and 2 mm is normally specified for and what that thickness demands on site.

Project snapshot

HDPE liner at the former Badarpur power station site

The Badarpur Thermal Power Station, a 705 MW coal plant run by NTPC in south-east Delhi, closed permanently on 15 October 2018. Decades of operation left a large ash disposal area along the Agra Canal. NTPC has since been developing an eco park of about 884 acres over the closed station’s ash dyke, with plans that include woodland, water bodies and recreation.

Ocean has supplied this site before: 20,000 sq m of 500 micron liner for the water bodies at the NTPC Eco Park in Badarpur. The present supply is a different specification. At 1.8 mm and 2 mm, it is more than three times as thick, which points to a heavier-duty barrier.

What heavy-gauge HDPE is chosen for

Liners of 1.5 mm and above are specified where the barrier has to survive rough handling, high loads or long service, or where what it holds back must not reach the ground. On power station land and former ash areas, sheet of this gauge is typically used for:

• Ash pond and ash dyke lining, to stop leachate from ash moving into groundwater.
• Containment of contaminated or reworked fill, as a base or cap barrier.
• Deep water bodies and reservoirs, where the head of water and the cover soil load are high.
• Effluent and stormwater lagoons on industrial land.

Ocean’s HDPE liner for a thermal power project in Singrauli and its 1500 micron pollution control liner in Sundergarh are examples of the same kind of work.

1.8 mm against 2 mm

GRI-GM13, the reference specification for HDPE geomembranes, gives minimum average values for smooth sheet at 1.5 mm and 2.0 mm. A 1.8 mm sheet falls between the two tabulated columns, so its acceptance values are normally set in the tender, often by interpolation.

Every thickness must also meet 0.940 g/cm³ minimum density, 2.0–3.0% carbon black, 500 hours stress crack resistance (ASTM D5397), and an oxidative induction time of 100 minutes standard OIT or 400 minutes high-pressure OIT.

Using two thicknesses on one project is common. Designers put the thicker sheet where the risk is highest, such as sumps, steep side slopes, areas under heavy cover or plant access, and inlet and outlet structures, and the lighter gauge across the main floor. By weight, the 25,000 sq m supplied comes to roughly 43 tonnes of sheet.

Working with thick HDPE on site

Thick sheet is stiff, and that changes how it is handled:

1. Subgrade. Ash, reworked fill and demolition debris often hide hard, angular pieces. Trim and proof-roll the base, and lay a non woven geotextile cushion where it cannot be made smooth.
2. Thermal movement. A 2 mm black sheet expands in the Delhi summer sun and forms wrinkles that do not lie flat under cover. Lay and cover in the cooler part of the day where possible.
3. Welding. Fusion welders need settings matched to the thickness. Run trial seams at the start of each shift and after any break, and test them in peel and shear.
4. Seam testing. Air-pressure test double-track fusion seams and vacuum-box test extrusion welds.
5. Anchoring. Heavier sheet pulls harder on its anchor trench, so size the trench for the gauge.
6. Cover. Place cover soil from the toe up, with a minimum lift over the sheet before any plant runs on it.

Frequently asked questions

Ocean Non Wovens

Ocean Non Wovens manufactures HDPE liners from 0.5 mm to 3 mm in smooth and textured finish, plus the geotextiles and clay liners used with them. For ash pond, containment or reservoir lining on power and industrial land, contact Ocean Non Wovens with the area, depth and what the liner must hold back.