Subsurface drainage collection system for Sydney parking lot

Project Background

At Kings Park near Blacktown in Sydney’s west, a car parking facility is being upgraded to better serve the surrounding tenants. The excavation work being undertaken for the project provides a convenient opportunity to upgrade the subsurface drainage system.

Problem

The low-lying area has a requirement to capture the surface and subsurface water into a safe collection point.

Traditionally this would be achieved with an extensive application of aggregate fill, which is heavy, time-consuming to install, and puts unnecessary environmental pressure on upstream resources by relying on expensive quarried material.

Sourcing traditional drainage aggregate is becoming increasingly difficult due to demands on the quarries and the uplift of construction within Australia. These factors have combined to significantly increase the cost of these materials.

Additionally, the ongoing challenges of the pandemic have impacted the production of these critical raw materials, creating longer lead times.

Solution

The contractor partnered with Global Synthetics to utilise the latest geosynthetic technology from Canada, which completely replaced the need for any drainage aggregate.

The use of this lightweight drainage blanket called Draintube® provided an effective subsurface drainage solution.

Supplied on a roll and easy to install, Draintube® has a multi-layered construction that includes small-diameter corrugated pipes sandwiched between two layers of geosynthetic fabric. The drainage layer is made up of 20mm or 25mm diameter mini-tubes, and the two filter layers are made from synthetic staple fibres made of 100% polypropylene or polyester.

This ‘sandwich’ is then needle-punched together, with the perforated corrugated polypropylene mini pipes regularly spaced inside. With multiple perforations at different angles, each corrugation provides effective drainage performance through 180° and 90° planes.

Draintube® is manufactured by leading Canadian geosynthetics company Afitex-Texel, which has streamlined the specification and design process through custom software. A multi-linear drainage geocomposite can easily be designed using complementary software called Lymphea.

Once designed and manufactured the quick connect system makes for an extremely fast installation to an existing subsurface drainage pipe network. The water is funnelled into the piping network and is carried off to a dedicated discharge point.

Overall, the speed of installation, as well as the material cost, saved the contractor ~20% of the original estimations.

To find out more about Draintube® and how you can speed up your next subsurface drainage project, get in touch with the team at Global Synthetics.