Remediation of Contaminated Sites

In the third quarter of 2023, a state-of-the-art washing plant for PFAS-contaminated groundwater - we reported that the soil was enriched with PFAS-containing substances as a result of extinguishing foam discharges during legally required fire drills at Salzburg Airport - was built on the airport site. This facility went into operation on January 1, 2024 and is in operation 24 hours a day, 7 days a week. The washing plant is fed with PFAS-enriched groundwater from 7 groundwater wells, which is fed back into the groundwater body via three so-called absorption wells after filtration and purification. This measure is intended to prevent PFAS-contaminated groundwater from entering the airport's groundwater plume. It cannot be estimated at the present time, how long this filter system will be in operation.

Timeline 

• Installation of the containers for the plant’s control technology and installation of two sedimentation tanks on September 20, 2023.
• Delivery & installation of sand filters and activated carbon tanks on September 21, 2023 with filling of the filter towers with gravel and activated carbon
• Commissioning of the plant on January 1, 2024

Groundwater purification plant

• consists of 2 sedimentation tanks, 2 gravel filters and 3 activated carbon filters and a control container 
• after the purification process (operated centrally via a control system, monitored by a close-meshed analysis network), clean water is fed into the groundwater body via three "absorption wells"
• the system requires an area of approximately 8.5 x 30 m; height of the activated carbon filter is approx. 10 m
• Output: 25 liters per second are pumped and returned to the groundwater body in a purified state
   

Once the purification silos for technical remediation phase 1 have been filled with gravel and activated carbon for groundwater purification, the groundwater purification plant is in the "commissioning phase".

Seven wells pump the contaminated groundwater to the groundwater purification plant, the purified groundwater is then fed back into the groundwater body via so-called absorption wells. This measure is accompanied by an extensive monitoring process, in close coordination with the water authority - in accordance with official regulations.

Over the next three years, samples will be taken and analyzed at internal and external measuring points - sometimes monthly, sometimes quarterly. Most of the samples can be taken during operating hours (06:00 to 23:00) with tower radio monitoring, while flight operations are maintained. Sampling between the runway and the taxiway as well as in the vicinity of the taxi guidance line of the main apron is carried out outside operating hours. The results of the sampling are transmitted to the authority in accordance with the prescribed information cycle, interpreted and further measures evaluated.
 

As already announced at the beginning of the year, the first phase of the remediation of the contaminated site "S23 Salzburg Airport" is being actively tackled. The filtration of the groundwater at the PFAS entry points will go into full operation in January 2024 at the latest. On September 20, 2023, the necessary containers for the control technology, the settling basins, the sand filters and activated carbon tanks for this first technical remediation phase have been delivered and installed. The second step in the first remediation phase will be the filling of the activated carbon tanks with activated carbon at the end of September, beginning of October, followed by test and trial runs before the plant goes into full operation at the beginning of 2024.

Description Securing/ Remediation of contaminated site S23 - Phase 1/ Hydraulic securing:
Initial situation
The Federal Ministry of Sustainability and Tourism (today: Ministry of Agriculture, Forestry, Regions and Water Management) detected elevated levels of PFAS substances in the groundwater of the airport as part of the project "Special measuring program for traces in groundwater". The cause was found to be extinguishing foam, which had presumably been used by the airport's fire department since the 1960s in the course of legally required extinguishing agent tests and extinguishing exercises. In addition to the immediate measures (new extinguishing foam, extinguishing agent samples and extinguishing exercises with foam no longer on the airport site, but on the premises of an authorized waste disposal company), the ALS team of experts (Salzburg Airport Contaminated Site Remediation Team) focused primarily on the long-term securing and remediation of the contaminated site. This requires a detailed planning process and will take an indefinite period of time (pioneering work in the PFAS contaminated site sector). The necessary authority procedures are very extensive and complex, the time factor is difficult to estimate.
Goal
The discharge of PFAS substances in the groundwater or further spreading of pollutants is to be prevented with the measures taken. In the first technical remediation phase, a hydraulic safety screen will be erected and commissioning is planned for early 2024.
Project content
Up to 7 groundwater wells will be constructed to allow the pumping of PFAS containing groundwater to a groundwater treatment plant. This groundwater purification plant consists of 2 settling basins, 2 gravel filters and several activated carbon filters. After the purification process (centrally operated by a control system, monitored by a close-meshed analysis network), clean water is fed to the groundwater body via three "absorption wells". In total, the plant requires an area of approx. 8.5 x 30 m. The activated carbon filter, which cleans the affected groundwater, has a height of approx. 10 meters. The company GWU Geologie - Wasser - Umwelt GmbH has been commissioned with the planning and local construction supervision, while ARGE NTA-BMA (consortium of the companies Porr Umwelttechnik GmbH and Bernegger GmbH) has been contracted as the executing company. 

Open questions will be added to the FAQs on the subject of contaminated site remediation and further questions can be sent to LJk0oTSmqTIhp2ShnJIlqJ5aDUAuoUcvqKWaYJScpaOipaDhLKD= .
 

Environmental monitoring of Salzburg Land - PFAS contamination and remediation of contaminated sites 
In the fall of 2022, the Nature and Environmental Protection Department of Salzburg Land commissioned an environmental monitoring project north of Salzburg Airport. The chemical and biological conditions of groundwater and surface water will be examined and checked for possible contamination by perfluorinated and polyfluorinated alkyl substances (PFAS). The city of Salzburg's tap and drinking water is not affected and is of the highest quality.

Citizens, who are interested in the monitoring area north of Salzburg Airport, have the opportunity to register for sampling by sending an e-mail to nJ5zo0O1oKqyoUEgo25cqT9lnJ5aYKAuoUcvqKWaYzS0.

More information on the environmental monitoring of Land Salzburg: www.salzburg.gv.at/themen/umwelt/abfall/altlasten/umweltmonitoring.
 

The investigations into the extent of the contaminated site have been largely completed; the northern boundary in the area of the main parking area is still being secured by further soil sampling. Salzburg Airport is endeavoring to implement the technical remediation of the contaminated site as comprehensively and quickly as possible as a result of the entry of firefighting foam containing PFAS from the company fire department. The issue of PFAS is currently of concern throughout Europe. In Austria, the provinces of Salzburg, Upper Austria and Styria are currently affected. However, the Federal Environment Agency is carrying out far-reaching investigations throughout Austria, and experts assume that such contamination of groundwater cannot be ruled out in the other federal states either.
A hydraulic securing measure will be used as initial measure for securing the contaminated site. The ultimate goal of the Contaminated Sites Remediation Act is to permanently secure aforementioned contaminated sites. To this end, the airport is already in contact with the agency responsible for funding contaminated site remediation measures, Kommunalkredit Public Consulting GmbH (KPC). 
The annual report to KPC must include the following information on the ongoing safeguarding measures:

• Summary assessment of the regularly measured relevant pollutants as well as statements about their development.
• Summary assessment of the effectiveness of the measures on the basis of the results of the preservation of evidence with regard to the relevant pollutants and the relevant protected resource groundwater.
• Prognosis of the further development of the relevant pollutants in the object of protection as well as estimation of the future operating expenditure (duration/scope)
• Protective measure for optimizing the plant with regard to the economic operation of the plant and the scope of measures for the preservation of evidence 
• on the basis of the above mentioned points, justification of the necessity and expediency of continuing the measures

The annual report is also sent to the Umweltbundesamt GmbH (Federal Environmental Agency).

Statement on the remediation variant study by the Federal Environment Agency (UBA)
Due to the identified "PFAS extinguishing foam contaminated site" in the groundwater plume of Salzburg Airport, this site was classified as a "Priority 1 contaminated site" in accordance with the criteria for priority classification. For the remediation of this contaminated site, the GWU Geologie-Wasser-Umwelt GmbH, on behalf of the Salzburger Flughafen GmbH, submitted the remediation variant study on October 21, 2022. Based on the current state of knowledge, the best option identified, appears to be fundamentally suitable for achieving the remediation objective, provided that the measures are planned and executed appropriately and suitable control measures are implemented in addition.

Please find the statement of the Federal Environment Agency, Department of Contaminated Sites, here: Statement on the remediation variant study (German Version)

The Federal Ministry of Sustainability and Tourism found elevated levels of so-called PFAS (perfluorinated surfactants) substances in groundwater during the investigation. The airport reacted immediately and promptly after the Ministry's measurement results became available. It must be emphasized that at Salzburg Airport, only extinguishing agents that complied with all legal requirements and technical standards were used at all times. The state of scientific knowledge and the legal requirements based on it are constantly evolving, and what was state of the art a few years ago and absolutely necessary for safety reasons, may lead to costly remediation work a few years later.

Brief Explanation PFAS
PFAS is an abbreviation for per- and polyfluorinated alkyl substances, also known by the older name PFC.

Applications of PFAS
PFAS substances, such as those contained in fire-fighting foams, have been used in many technical areas and in industry in recent decades. Examples are the production of non-stick coated pans, cake pans, water and dirt repellent textile clothing, paints, varnishes, polishing agents and many other products of everyday life.  

Determining the cause and first steps
In coordination with the authority, the potential causes for the PFAS contamination were first determined. This revealed that airport firefighting foam was the cause of the contamination. As an immediate measure, firefighting tests using this foam agent were immediately prohibited and a new firefighting foam was purchased. The fire extinguishing agent samples and fire extinguishing exercises, which are still required by law, are no longer carried out on the airport site, but on the premises of an authorized waste disposal company. A comprehensive situation report was drawn up in close cooperation with the relevant authorities. Initial considerations for remediation of the contaminated site have already been made.

Historical Review
The PFAS-containing extinguishing foam has already been used in the 1960s until 2018. PFAS-containing extinguishing foams are not specific to Salzburg; this type of extinguishing agent was and is used worldwide to fight special fires (liquid substances such as gasoline, kerosene, heating oil, tar, alcohol, etc.). At Salzburg Airport, extinguishing foams have never had to be used in an emergency. The quantities of extinguishing agents used in extinguishing agent tests and legally prescribed extinguishing exercises are very small. 

Preparatory work for the remediation of contaminated sites
All measures for the remediation of the contaminated site are being coordinated with experts from the Federal Environment Agency, the state's official experts, the Salzburg GWU, the Salzburg Hydrological Investigation Office and renowned German PFAS experts. All affected residents of whom the airport or the authorities have knowledge on the basis of the data currently available, have already been personally contacted and informed. From the current expert point of view, there are no problematic uses of the affected groundwater.

Goal
The goal is to find the best possible remediation solution for the environment, people and nature. The measures are based on the groundwater limit value that will apply in the EU member states from January 2026 (sum of PFAS of 0.10 μg/l).