Londonderry PFAS Treatment & Capping Works

Over the last few decades, the TestSafe facility has been home to various fire training exercises and firefighting trials with Fire and Rescue NSW. The runoff from fire-fighting foams has contaminated the site and made its way into several stormwater retention dams across the site. The dams ranged in levels of contamination but, on average, had around 85µg/L of total per- and poly – fluoroalkyl substances (PFAS) ranging from the shorter chain PFAS molecules up to the larger longer chains such as PFOS. There were also other various competing co-contaminants in the dam, such as fulvic and humic acids.

TestSafe NSW engaged SciDev to dewater the dams, treat the contaminated water, dispose of the contaminated sediments, and upgrade the stormwater retention dams. Water treatment activities remain ongoing, as fire training exercises continue to be carried out on the site, and contaminated stormwater continues to be generated. The Temporary Water Treatment Plant (TWTP) has been mobilised and commissioned five times in total to undertake water treatment activities on site. To date, the TWTP has treated and discharged 6.9 megalitres to the environment without the need for media replacement or disposal of waste generated.

Summary

• Design, construct, and commission a TWTP capable of treating up to 2.8L/s with continuous discharge to the environment via drip irrigation in accordance with our NSW Environmental Protection Agency license.
• The final retention dam was reshaped to increase the holding capacity from 209kL to 610kL and lined with a HDPE liner to prevent leaching of contaminated water.
• SciDev has now remediated and capped two of the original three secondary retention dams on-site, transporting and disposing of up to 438.5 tonnes of Restricted Solid Waste and 520.1 tonnes of General Solid Waste.
• A concrete spillway was designed and constructed to allow for controlled overflow and to reduce erosion.
• The TWTP has treated and discharged 6.9 megalitres to the environment without the need for media replacement or disposal of waste generated.