Enviro Liner 6040 Brine Pond Ballast Pillows – QGC Water treatment Plant
LOCATION: Chinchilla, Queensland, Australia
DATE OF INSTALLATION: 2013
SCOPE OF WORK: Ballasting pillow system to maintain integrity of double lined brine pond liner utilizing EL6040 material.
PROJECT OWNER: QGC/Jaylon
Project Background and Challenges
As part of the development of the coal seam gas (CSG) fields in south central Queensland, Australia, water treatment is required to process saline ground water released out of the gas wells. The water is treated through reverse osmosis treatment plants to recover up to 97% for beneficial re-use. The reject stream is further treated in brine concentrators. The resulting salt and brine is stored in double lined storage ponds. The lining system used a primary and secondary liner with leak detection between the liners. To minimise leakage rates the primary liner was required to be kept in intimate contact with the secondary liner at all times and not allowed to float. The project faced significant challenges with the strict environmental requirements, project deadlines and physical size of the pond. The brine storage pond was 540m by 330m with a floor area of 104,400m2 (435m by 240m).
Solution and Results
To keep the geosynthetic primary liner in intimate contact with the geosynthetic secondary liner, large flat ballast pillows were designed to be installed over the double liner system. The pillows, measuring 15m by 3.63m by 0.1m, were factory fabricated by the lining contractor, folded and delivered to site.
Enviro Liner® 6040 (EL6040) geomembrane in a 1.0mm (40mil) thickness was selected because of its superior resistance to brine, outstanding UV capability, high tensile strength and flexibility. Flexibility was very important since the pillows needed to be factory fabricated, packaged and sent to site without experiencing any damage. EL6040 is manufactured with special prime grade resins and an advanced antioxidant package
Due to the size of the storage pond and project timing deadlines, the final earthworks, secondary liner, primary liner and ballast pillows were all installed progressively. Once installed the ballast pillows were filled to a thickness of 100mm with grout. A total of 1800 pillows were installed in the pond covering the entire floor area.
The ballast pillows also provided secondary benefits. The pillows maintained the geosynthetic liner system in the as-installed condition, resisting wind up lift and eliminated thermal movement due to the high solar loading in the region.
The ballast pillows have been a very effective part of the geosythetic lining system and have performed above everyone’s expectations. They are an innovative and cost effective way of increasing the performance of double lined liquid containment storages. This project has prompted their use in other applications including cushion layers for aerators, pontoon mounted equipment, jetties etc. where damage could potentially occur to the lining system.
Layfield is a leading vertically integrated company that specializes in providing environmental containment systems and solutions. Our products and services are commonly used by the Oil & Gas, Mining, Energy, Municipal Water, Agriculture, Civil Construction, and Waste Management sectors. Layfield has been in business since 1978 and is an ISO 9000 registered company.