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What are the most appropriate practices for waste management?

This discussion ranged over the improvement of landfill liners, development of PFOS and PFOA separation techniques from the wastewater streams and the identification of ambiguities in the waste exemption permit. 

Phil Henderson (Coffey International) promoted the use of more insulative liners, less prone to seepage in landfills, such as those used in New York or Germany. In those countries, their guidelines place a higher value on groundwater with quantity and quality approval requirements for any leachate which leaks through the liners. With his Victorian background on landfill design and auditing process, Henderson explained how composite, double composite liners with geomembrane layers may be better suited to some conditions rather than the conventional basal liner design. However, they require immediate containment and confinement. Overall, the key to the success of any landfill liner is quality assurance with the importance placed on a Construction Quality Assurance plan during installation. The use of geosynthetic liners require constant contact with the waste being contained. Leakage detection can be installed for a relatively low cost using voltage across the liner to observe any holes. Such liners have been used in Australia as both geomembrane or clay liners can be effective if utilised under conditions suited to their qualities.

Current research on the separation Poly-fluorinated Per- and poly-fluoroalkyl substances (PFAS) from wastewater and solid waste streams is underway. Focusing on Perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) separation, Professor William Clarke (University of Queensland) explained possible techniques for trapping PFOA at wastewater plants. One research project at the University of Queensland involves mixing Iron oxide (Fe2O3) nanoparticles with the waste such that the nano-magnetite absorbs PFOA into the thickened sludge. This can then be mixed in water and collected with a magnet, for separation from the waste stream. Other techniques such as incineration were also discussed and there is some research focusing on the destruction of PFAS through non-thermal and thermal plasma (similar to the methods used for the destruction of Perfluorinated compounds (PFCs) in its early stages).  

The waste exemption was discussed with regard to unclear definitions and criteria which may be of concern to those wishing to utilise it. After identifying a series of observable ‘gaps’ in the waste exemption, Louise Cartwright (PSK Environmental) queried the Department of Environment and Science (DES) for clarification. The Environmental Protection Act (EP Act) defines ‘earth’ as sand, soil, silt or mud and the definition in the Waste Reduction and Recycling Act (2011) considers natural materials such as clay, gravel, sand, soil and rock. Therefore, this reference to “natural” earth in the Waste Reduction and Recycling Act (2011) does not incorporate fill material? Furthermore, there is no definition for “natural” provided in the legislation potentially causing misinterpretation within the industry. With fines and penalties for the misuse of the waste exemption, these definitions may require further distinction. Further ambiguities were identified in the eligibility criteria for the waste exemption. For the exemption to be applied earth must be reasonably treated by bioremediation. There is no clear consideration of different remediation techniques and expects that earth solely contaminated by petrol hydrocarbons to be treated on site. Furthermore, DES reported that ‘reasonably treated’ is what is cost effective? The overall feedback from DES regarding this and the presence of contamination prior to 1992 is that it is up to the waste exemption declaration signatory to provide evidence of all criteria.

The outcomes of this discussion were that there should be some workshopping with DES to clarify the definition of earth, develop some consideration for the contaminants present and potentially develop a suitable waste management guideline document for the waste exemption. Furthermore, training for the applications of bioremediation and the utilisation of other remediation techniques may be required and discussed with DES to reduce the likelihood of miscomprehension and misuse of the waste exemption. 

19 September 2019 New Zealand Branch report by Lauren Reynolds – Graduate Environmental Engineer - WSP

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Per and Poly- Fluoroalkyl Substances (PFAS) are a heavily discussed topic at present and until their impacts on human and environmental health are fully understood they must be carefully monitored and managed.

One of the most common analytical techniques in PFAS soil and water contamination investigations is Total Oxidable Precursor Assay (TOPA) which oxidises unknown precursor fluorinated compounds into detectable PFAS.. Marc Centner from ALS Environmental discussed the applications and limitations of TOPA laboratory analysis. The focus of analysis was  0.5% to 1.5% fluorosurfactant products which are used to reverse engineer substances, such as Aqueous Film-Forming Foam (AFFF) or Firefighting Foam, to identify partially fluorinated substances such as perfluoro alkyl butane which is a precursor to Perfluorooctanoic Acid (PFOA). Other precursors such as Persulfate are heat activated, have highly heat sensitive half-lives and oxidise at a high pH. If the pH decreases sufficiently, oxidation ceases to take place and sulfate radicals form due to chain shortening.

Empirical analyses and dilutions at present are the only responses available, though with dilution comes the potential to dilute beyond the guideline standards which may cause interlab inconsistency. However, as long as the oxidant and the base are consistent there is no need for empirical analysis. Limitations during analysis of a sample arise as oxidation causes a loss of the total mass of butane and there is potential for incomplete oxidation. This results in a vast variety of different chain lengths only a portion of which are able to be identified through TOPA.

With regard to reducing these limitations, the 2018 ALGA R&D Grant winner research project focused on “improving measurement reliability of the PFAS TOPA”. Annette Nolan, the lead consultant at Ramboll Australia, discussed how the grant was utilised to benefit the industry.

Currently, approximately 4700 PFAS substances have been identified and approximately 90% of precursors making the risks of PFAS contamination difficult to estimate. It was found that in waste water treatment plants, precursors are more prevalent in influent waste streams than effluent because pre-treatment converts precursors into carboxylic acid by-products. As such, TOPA should be utilised when there is a semi-quantitative risk from precursors. TOPA does not mimic the natural environment, it cannot incorporate oxidation and loses mass and precursors during its conversion. It targets and identifies the maximum chain length PFAS. Thus, the sum of PFAS post-TOPA is generally greater than the total PFAS pre-TOPA due to the precursors conversion into carboxylic acids and sulfonic acids post-TOPA. QA/QCs monitor precursors identified during oxidation and oxidise to target analytes and surrogates. The National Environmental Management Plan (NEMP) states that the performance of TOPA will be masked in aqueous samples if:

Overall, it is the consultant’s responsibility to review the QA/QC and ensure that the laboratory’s limit of reporting (LOR) is fit for purpose.

PFAS are impacting a range of primary productions, industries, waterways and wetlands. Bearing in mind that environmental harm can incorporate any adverse or potentially adverse effects (Environmental Protection Act (EPA), 1994), PFAS are considered a regulated and trackable waste requiring containment and treatment to a concentration less than the LOR. With such a broad spectrum of PFAS -- with significantly more unknown than observable PFAS -- and precursors, only a portion of them can be analysed with TOPA. 

Tony Bradshaw from the Department of Environment and Science (DES) discussed why TOPA is still an important analytical technique. Fluorotelomer carboxylic acids have been identified in landfill leachate under anaerobic digestion which are a precursor though are not in the main TOPA suite. Furthermore, precursors in fish accumulate PFAS over time which convert into sulfonic acids. PFAA accumulate in plants becoming PFOS, C4, C6 and C8 through aerobic transformation. These are identifiable through TOPA. TOPA can identify up to 250 times more PFAS than standard PFAS analysis. Even dairy cows exposed to precursors can accumulate PFAS in their milk. Shorter chain length carboxylic acids absorbed in plants (such as PFHxS) and accumulated in invertebrates are unaffected under TOPA which targets more absorbable PFAS though electrochemical fluorination and telomerisation production (PFAS production). This telomerisation allows different chain lengths to become observable. Pre-TOPA provides an underestimation of PFAS present while TOPA provides the precursors and their significance. Despite some mixed reviews, Bradshaw reminds us that it is an analysis tool and to keep up with the scientific developments on PFAS and that laboratories will unlikely adapt their LORs or alter their analysis until DES guidelines change.

A point of discussion was the shift of focus from long chain PFAS (such as AFFF) to short chain PFAS potentially giving rise to Total Organic Fluorine (TOF) analysis. However, it was concluded that the science of the effects of PFAS on people will dictate the future of PFAS treatment.

10 October 2019 New Zealand Branch report by Lauren Reynolds – Graduate Environmental Engineer - WSP

Didn't get to attend the event, but would love to review the presentations? Go to the ALGA online library*

* note the access to all the papers in our online library is a member only benefit, for more information or to join click here

These presentations were on quite different topics, having said that, the importance of an accurate conceptual site model was a common  point.

Highlighted was the need to look at contamination in air, particularly where ventiulation systems are present – may need to be included in the conceptual site model.

Main points:

(a) Bringing bioavailability to the fold.

• Seasonality of elevated arsenic?  This was unclear.  There are still a lot of unknowns with bioavailability and what is happening in the volcanic north island may be quite different from what is happening in the south island.
• Update to background concs documents, but how would this be done given how specific the areas of elevated arsenic are?
• There will be other areas of Christchurch with elevated arsenic?  Eg Port Hills volcanic soils
• How does the elevated arsenic affect landfill disposal options, e.g. cleanfill?

(b) What lies beneath. High Resolution Site Characterisation Tools used ot develop LNAPL Conceptual Site Model. 

This focused on the use of unit volumes of subsurface to avoid excessive averaging of the property and providing detail cirtical for informed decision making.

However, these are expensive tools. Used a lot in Australia but rarely in NZ.  Expensive to bring over. 

(c) Mixed contamination assessment and management at a zinc galvanizing plant

Case study of a site based in Sydney in a mixed land use area, river located to the south.

The investigation found PFAS in just about every stage of the galvanizing process, even when suppliers confirmed their products were PFAS free.The most intersting finding was PFAS on the roof, suggesting that airborne contaminants need to be included in some conceptual site models.  This seemed to be the most significant paway at the site.  However, the process of multiple phases of investigations also led to improvements in the running of the plant as the owners became more aware of how their hazardous substance mmanagement was leading to contamination of soil, stormwater and air.

(d) Correlating asbestos containing material in buldings with concentrations in soil: A New Zealand Based Study.

• Surface soil scrapes following demolition are a good method to remediate a site without the need for an investigation – go straight to validation sampling. 
• The ENGEO datset gives an indication what level of asbestos is likely to be found based on the properties of the site structure, and the results are not surprising.  For example, 1960s properties gave greatest likelihood for HH significant results in surrounding soil.
• Asbestos ‘super 6’ roof data set is high risk based on the results obtained, therfore more sampling would be good at known high risk sites to delineate this risk?
• The ENGEO study has lead to Auckland Council (AC) now requesting testing for asbestos routinely with pre – 2000s properties. However, the audience was unclear how AC can justify requiring testing for asbestos - what is the legal reason that would require this.  More likely than not legal test (>50%) only exceeded for the most high risk sites (1960s).
• There are still plenty of other variables that would affect asbestos in soil, eg use of sander.

Context, the results are unlikely to give asbestos in air non compliances as the affected area is so limited.  We need to be careful not to remediate when this is not necessary.

However, disposal of excess soil will still be an issue – haven’t ceritified the soil is asbestos free.

It was noted that the difficulty getting expensive tools into NZ for our cheap and cheerful investigations is an ongoing issue.

In the spirit of improving processes, all four presentations focussed on looking at your results in detail to get suitable remediation strategies, or obtaining more in depth information on a site before deciding on the remedial action plan.

8 October 2019 New Zealand Branch report by Helen Davies - AURECON

Didn't get to attend the event, but would love to review the presentations? Go to the ALGA online library*

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Landfills pose hazards; long-lived wastes such as plastics, putrescible and organic matter (landfill gas) and location (due to climate change). Increasing pressure to develop land close to or even on closed landfill sites has increased the likelihood of landfill gas impacting on sensitive receptors.

The highlight of the presentation was the ability for landfills to have impacts that extend beyond their boundaries for decades or more was the most powerful point.

Feedback from student attendees was also very positive. They had significant interest in contaminated land, and expressed that had not had much exposure to the variety of disciplines that converge in contaminated land management and investigations. They also expressed surprise at the broad range of expertise, from ecology to engineering, and chemistry to GIS – people with a broad range of skills and backgrounds were present and were accepting and very willing to share their stories with the students.

Communicating the risks posed by landfills was a key point. Another great point was seeing the use of techniques developed for one application (service stations in this case) being modified to identify and communicate risks in another sector (closed landfills).

What was not resolved to date was how NZ is going to deal with closed landfills vulnerable to the effects of climate change was a challenging question with no definite answer. Landfill gas monitoring can be done better, but whether it can be improved (affordably) with the equipment available in NZ currently was also a challenge. Landfill acceptance criteria were questioned.

The question was raised of how to improve the process. We need to keep talking about landfills, and constantly strive for better ways of identifying, communicating and managing the multitude of risks posed by landfills, and indeed any contaminated sites.

17 October 2019 New Zealand Branch report.

Didn't get to attend the event, but would love to review the presentations? Go to the ALGA online library*

* note the access to all the papers in our online library is a member only benefit, for more information or to join click here

Woodville North, Athol Park & Pennington residents may be aware that the Environment Protection Authority (EPA) has been undertaking environmental assessment work in your area, to ensure that the legacy of past industrial practices does not pose a risk to residents living there today.

The results of the first stage of work in Woodville North, Athol Park and Pennington has confirmed that the groundwater is contaminated with trichloroethene (TCE) and other chemicals, and should not be used for any purpose. There are no results confirming indoor air contamination, but a computer model has been used to predict which houses might need further testing. In a small number of homes, the EPA has asked residents if testing can occur on their property. The next stage of work will include soil vapour sampling on five private properties closer to residential buildings and underneath floors. If necessary, it may then include testing of indoor air.

All residents have been advised that soil, rainwater and mains water are not affected. Contaminated groundwater does not generally contaminate the soil above it unless it is used for irrigation or it is the source of the contamination. Home grown vegetables are safe to eat, provided residents are not watering them with bore water. Residents whose homes have basements have been asked to contact the EPA to find out if there is any additional risk, based on their usage and location.

The EPA is hosting a community information session, and you are invited to attend if you would like to speak with our staff and ask any questions you might have.

Thursday 31 October 2019
4pm-7pm ‘drop in’ anytime
The Port Club, Port Adelaide Football Club
Corner of Queen Street and Brougham Place,  Alberton

Please click here to download a copy of the community update that is being delivered to residents today.  A copy of the map, report, previous correspondence and other information is available from the EPA’s online engagement site, Engage EPA.  If you have any questions at all, please don’t hesitate to let the EPA know.