PFAS Remediation With GAC Velocity Bags
Project Material has designed and developed a series of high grade, engineered bags with the sole purpose of filtering contaminated water, particularly for PFAS remediation.
Through our extensive research and materials knowledge we worked closely with industry experts to design and develop GAC Velocity Bags.
The initial and primary project was PFAS remediation works at RAAF Williamtown NSW.
Unfortunately most airports and RAAF bases around Australia, if not the world have varying levels PFAS contamination through long term discharge of fire fighting foam, typically from training exercises conducted as part of operational skills in fire fighting.
The GAC Velocity Bags with proprietary internal media was designed and installed as an extensive passive barrier system to filter PFAS contaminated water being subsurface, and surface run off with various culverts and drainage points flowing into and out of Lake Cochrane, a man made lake internal to Williamtown RAAF base.
At these particular drain locations PFAS concentration was measured as high.
The culverts previously carried PFAS contaminated water into neighbouring properties and local creeks, ultimately moving through the local eco-system and marine food chain.
The GAC Velocity Bags have proven extremely successful with regular testing showing 95+% absorption of PFAS in the locations the GAC Velocity Bags have been installed.
The bags are manufactured from UV stable, high velocity materials of various sizes to meet the rigorous demands of Civil and Mining applications.
Complete with heavy duty lifting straps and supplied with specialty media blends the bags are efficiently lifted into position with crane or machinery.
In comparison to other PFAS remediation systems the cost savings and installation efficiencies are remarkable. Below is further details pertaining to the concept and installation.
PFAS Passive Barrier Concept
Passive technology treats water in-place rather than pumping it to and from a water treatment plant, allowing water to naturally flow to and from Lake Cochran.
Installation began during the highest rainfall event recorded in July in 73 years. The mean rainfall during July from 1942-2020 is 72.6mm and during July 2020 the rainfall was 242.6 mm (BOM,2020). The outcome from installing the system during the large rainfall event confirmed that our contingency design for flood events was successful with no visible ponding or flooding upstream. Lake Cochran began overflowing on the 27th July 2020 and ceased overflowing on the 14th September 2020.
Stage 1 Inflow: Legion
Passive Filtration Bags – Incoming drain to Lake Cochran
The Legion treatment stage is a simplistic modular scalable treatment system, that creates a permeable barrier wall through which the process water passes. This treatment system will remove organics including PFAS and clarifies the water. Large-granule activated carbon was enclosed within 1m3 and 0.5 m3 passive remediation bags (PRBs) which were stacked 1.5 metre high in a barrier extending the full width of the incoming drain with a volume of 60m3. AquaRockBags (ARB) were installed at each end of the installation to offer physical filtration and stability.
Stage 2 Outflow: Bastion
Passive Filtration Bags – Lake Cochran next to weir
To mitigate the risk of ponding/flooding and to make use of the available area, the contractor installed the first treatment stage for the Lake Outflow, Bastion, on the lake side of the weir. The infrastructure for the Bastion stage at the Lake Outflow is the same as the Legion stage at Lake Inflow. The barrier was installed in the south west corner of the lake close to the weir and is 1.5 metres high to with a volume of 40m3.
Stage 3 Outflow:
Weir Box System – Weir from Lake Cochran to Dawsons Drain
The Cavalier stage was installed the Bastion System on the drain-side of the weir. In collaboration with Australian Industrial Plastics, designed a gravity fed cartridge-style weir box filtration system. The design of the system aims to ensure water flows evenly through the system to provide consistent treatment outcomes. The system has four parallel lead-lag boxes with internal dimensions that house 20m3 volume.
Custom Filtration Media
Further more the internal proprietary media can be altered to suit an array of other contaminated water projects such as mining, rail, civil works, agriculture, land fill etc.
Please feel free to call one of our experts to discuss upcoming projects where PFAS remediation or other other industrial water contamination remediation is required.