December 2017

Australian Government Department of Defence

RAAF Base Tindal – Investigation Area PFAS Investigation and Management Program

RAAF Base Tindal Investigation Area In March 2017, Defence engaged independent environmental consultant Coffey to conduct a detailed environmental investigation into poly-fluoroalkyl substances (PFAS), on and in the surrounding area of, RAAF Base Tindal.

The first stage of the investigation, the Preliminary Site Investigation (PSI), has now been completed. The second and current stage of investigation, the Detailed Site Investigation (DSI) commenced in April 2017 and involves the sampling of soil, sediment, groundwater and surface water both on- and off-base as well as bore drilling and the installation of groundwater monitoring. Findings from the DSI will inform the Human Health and Ecological Risk Assessment.

The Investigation Area (see Figure 1) was determined and refined as a result of the initial investigation findings. The Investigation Area has been determined by understanding the soil, water flow and aquifer boundaries as well as where testing confirmed no detectable concentrations of PFAS.

PFAS in the Investigation Area How does PFAS move from the Base and at what concentrations?

PFAS moves off-base at RAAF Base Tindal by leaching into the Tindall Aquifer (groundwater) and through surface water run-off via drains and Tindal Creek.

The highest concentrations of PFAS in groundwater are in a zone that goes from the Base through to the Katherine River, alongside the Stuart Highway.

PFAS concentrations are mainly distributed evenly through the Tindall Aquifer where bores are drawing water from. However, rainwater is diluting concentrations at shallow depths near Katherine.

There is a band approximately 4km wide where concentrations are above guidance values for drinking water, and 2km to 3km wide where concentrations are above guidance values for recreational use (See Figure 2).

Testing has confirmed that based on the way PFAS moves in the environment; there is no means for PFAS to enter the Jinduckin Aquifer, except close to Tindal Creek.

Figure 1: Katherine Investigation Area

December 2017

Australian Government Department of Defence

Figure 2: Katherine Investigation Area showing PFAS concentrations in groundwater

Figure 3: Daily Basin showing the Tindall aquifer and Jinduckin Aquifer (Northern Territory Department of Land Resource Management, Report No. 13/2016D)

Figure 4: Tindall Aquifer water flow (Northern Territory Department of Land Resource Management, Report No. 13/2016D)

What soil testing has been completed? What are the outcomes of testing?

Extensive soil sampling was conducted on-base to understand the source areas of PFAS contamination and to help guide remediation and management efforts. Soil samples were also collected where contaminated bore water is repeatedly used for irrigation.

At the end of dry season, PFAS had not accumulated in soils at levels above the Screening Criteria in soils in irrigated areas on-base or in Katherine. There is minimal exposure risk to PFAS from sports grounds and school ovals that are watered with groundwater containing PFAS as the risk of PFAS exposure from skin contact, inhalation of dust, or accidental ingestion of soil and dust is low.

PFAS concentrations within soil in the Uralla area do not present an exposure risk through direct contact, but would potentially present a risk though PFAS uptake into home-grown foods. The Interim Human Health Risk Assessment (IHHRA) provides further advice about the consumption of home-grown produce.

Is the Katherine River impacted?

The Tindall Aquifer flows underground from the eastern and western side of the Katherine River in the direction of the River (see Figure 3). Groundwater from each side meets at the Katherine River and is not known to flow past the area of the river.

Groundwater travelling off-base via the Tindall Aquifer flows into the Katherine River through springs and seeps along the river bank (see Figure 5). Some groundwater flows under the River before discharging to springs, but this is limited to areas very close to the river.

December 2017

Australian Government Department of Defence

Pumping water from major production bores on the eastern side of the River appears to have drawn PFAS contamination sideways from the natural flow of direction.

Sampling of the Katherine River has confirmed that PFAS enters the river through springs and seeps along a section between Knott’s Crossing and the railway bridge.

PFAS concentrations in the Katherine River between the Stuart Highway and the Daly River exceed guidance values for drinking. Water from the Katherine River should not be used as the primary source of drinking water in this area.

PFAS concentrations in the Katherine River are not above Health Based Guidance Values for recreational use, and therefore contact with river water while swimming or irrigating is not a risk to human health.

I live inside the Investigation Area. What does this mean for me?

Residents with a town water connection can continue to drink the town water. The Katherine town water supply is safe to drink, with recent testing confirming undetectable levels of PFAS.

The Katherine Town water supply is delivered to Katherine, Katherine East and RAAF Base Tindal and is a blend of river water and groundwater.

Residents living inside the investigation area who draw water from a bore or water from the Katherine River should limit their consumption. If testing has not already been organised for your water source contact the community hotline on 1800 316 813 to discuss your eligibility.

Areas outside of the Investigation Area What are the results of testing outside of the Investigation Area?

Extensive testing has been conducted and PFAS has not been detected in ground water at the following locations:

• Lansdowne area (Lansdowne Road, Niceforo Road)

• Gorge Road, north of Morris Road

• Cossack area (Florina Road, Zimin Drive, Tokmakoff Road, Shadforth Road).

One detection in ground water has been found on the western side of the Katherine River at a Katherine Town Council bore.

Figure 5: Katherine Conceptual Site Model showing the water flow from RAAF Base Tindal

December 2017

Australian Government Department of Defence

This deep bore is within the Investigation Area and is the only detectable result on the western side of the Katherine River. This bore may be impacted by PFAS contamination because it is drilled into a deep flow from the eastern side of the river. The deep flow moves under the river before looping back and discharging into the Katherine River.

Most private bores in that area are shallow and no nearby bores have detected PFAS.

No pathway has been identified for PFAS to move from the Investigation Area.

I live outside of the Investigation Area. What does this mean for me?

Residents outside the Investigation Area who rely on bore water for drinking should be unaffected by PFAS, as there is no means for PFAS to travel outside the Investigation Area.

Residents who rely on the Katherine River (downstream of the Stuart Highway bridge) for drinking water should contact the Defence hotline to arrange testing for PFAS.

Interim Human Health Risk Assessment An Interim Human Health Risk Assessment (IHHRA) has been developed to inform residents of potential risks for PFAS exposure or ingestion.

For more information about the IHHRA and the recommendations on how to reduce exposure to PFAS refer to the RAAF Base Tindal – Interim Human Health Risk Assessment factsheet.

Contact Information RAAF Base Tindal community hotline

Phone 1800 316 813

Email PFAS.RAAFBaseTindal@coffey.com

Website www.defence.gov.au/environment/ pfas/Tindal

Post PO Box 2213, Palmerston NT 0830

Media enquiries should be directed to Defence Media

Operations on (02) 6127 1999 or media@defence.gov.au