A Technical review by CEM research director Charlie Pierce
Introduction
The Westconnex St Peters Interchange (formerly known as both the Alexandria Landfill and St Peters Landfill) contains a closed landfill which is presently managed by Transport for NSW (TfNSW) and regulated by the NSW Environment Protection Authority (NSW EPA). Closed landfills continue to represent a significant environmental risk for decades after closure due to methane generation and continuing leachate production.
In October 2023, CEM published its first update on TfNSW’s pollution monitoring at St Peters. In January 2024, CEM published a further update.
In February 2024, CEM published a report on the environment management of the St Peters Interchange. The report reviewed the evidence of pollution and mismanagement of the site and identified many weaknesses, gaps and concerns about TfNSW’s compliance with its conditions set out in its pollution licence. This report was sentence to the NSW EPA, Transport for NSW, the Inner West Council and Councillors, City of Sydney and Councillors and relevant Members of Parliament.
NSW EPA declares that St Peters Interchange is a contaminated site
On 25 June 2024, NSW EPA declared the St Peters Interchange to be significantly contaminated as a result of ongoing detections of elevated methane and carbon dioxide levels. This declaration means that the landfill would now be managed under the NSW Contaminated Land Management Act (CLM).
CEM was concerned that there was a potential for the current partial reporting by TfNSW of its environmental monitoring data to be even more difficult to access if the site was managed under legislation other than under Part 3 of the NSW Protection of the Environment Operations Act 1997 (POE Act) which requires licensed polluters to report specific environmental monitoring.
EPA meets with CEM
NSW EPA and CEM met on 2 July to discuss the implications for transparency and evaluation of monitoring results under the Contaminated Land Management Act. NSW EPA assured CEM that the current Environmental Permit Licence (4627) would continue. Under the CLM act, TfNSW will develop a plan to control pollution. This would include a monitoring plan to measure levels of methane escaping from the landfill. The purpose of the monitoring is to demonstrate that the TfNSW plan is working.
The EPA agreed to another meeting with CEM on 27 August to discuss the poor quality of monitoring and reporting by TfNSW contractors.
On 31 July, CEM sent the EPA some instances where TfNSW failed to report monitoring, missed monitoring events, reported erroneous data and failed standard water testing quality control checks.
CEM has had two meetings with EPA staff. The aim of these meetings was to have a meaningful discussion with the EPA about CEM’s concerns about the quality of the data. No staff were present at either meeting with apparent sufficient knowledge of the monitoring to discuss CEM’s concerns.
EPA’s Solid Waste guidelines
The NSW EPA uses their Environmental Guidelines: Solid Waste Landfill (2016) as the blueprint for regulating responsible landfill management. These environmental guidelines are based on best international practice and are intended to ameliorate potential environmental degradation.
These Environmental Guidelines: Solid Waste Landfill have specific requirements for the long-term monitoring of groundwater and leachate quality. The groundwater monitoring wells selected were nominated by TfNSW environmental consultants and accepted by NSW EPA as being important for assessing changes to groundwater conditions due to the landfill’s presence.
This report is an assessment of how well TfNSW is conducting this monitoring and identifying any overt evidence that the EPA is adequately regulating TfNSW’s performance. Some of the errors made by TfNSW and its contractors are technical and I have attempted to explain these mistakes clearly and concisely.
Evaluation of Landfill Environmental Monitoring at St Peters
This assessment is based on leachate and groundwater monitoring results reported by TfNSW between October 2020 to September 2023 https://www.transport.nsw.gov.au/operations/roads-and-waterways/environment-and-heritage/environmental-compliance/environment.
There are 11 different groundwater monitoring wells with quarterly sampling reported up to 12 times. There were 14 quarterly leachate reports assessed.
In general, leachate and groundwater monitoring results do not change greatly over time. Aside from seasonal effects, measurement changes over time are unidirectional; that is, they incrementally increase or decrease. Great variation between subsequent measurements is evidence of measurement errors.
There is no evidence that either TfNSW or NSW EPA were aware of the extent of the errors reported below except, of course, when CEM has directly reported these errors to them.
This raises serious questions about the role and attitude to compliance and public safety by staff in two NSW public agencies.
Who are the TfNSW’s consultants?
CEM specifically asked the NSW EPA in meetings and emails to identify the TfNSW’s environmental consultants and analytical laboratory. The reason for requesting this information was to enable CEM to determine whether these contracting organisations hold appropriate credentials to undertake this activity. The EPA has not provided this information to CEM to date.
The NSW EPA has a system of appointing Accredited Site Auditors. (Here is a list of currently accredited auditors.) TfNSW are required to use a NSW EPA Accredited Site Auditor to assess conditions and prepare reports on compliance.
Specifically, the EPA has required TfNSW to use an auditor:
- to prepare an interim report on the passive gas collection system by 30 September 2023 and a final report by 31 January 2024;
- to report on the rectification the landfill capping for an area of the landfill identified as RW101A by 30 June 2024; and
- to examine the accuracy and completeness of the sites monitoring data collected in accordance with EPL 4627, the Landfill Environment Management Plan (LEMP) and Landfill Management Closure Plan (LMCP) and the POE Act.
In our emails and discussions with the EPA, CEM has asked for copies of reports prepared by site auditors. No reports have been supplied. The NSW EPA replied that a final site audit statement containing further information about the site and its monitoring will be signed off when the site is suitable for use as a public parkland. CEM understands that there have been a substantial number of NSW Accredited Site Auditor reports already completed in relation to the contamination at the St Peters Interchange.
Site Monitoring Responsibilities
To comply with its Environmental Protection Licence, TfNSW have specific monitoring requirements that must be conducted by an environmental consultant at the landfill. These include physical and chemical measurements that must be performed on-site. They include the following:
- Standing water level measured as Australian Height Datum (AHD) in metres;
- Electrical conductivity measured in Microsiemens per centimetre (µS/cm);
- Oxidation reduction potential (Redox) measured in millivolts (mv) following conversion to Standard Hydrogen Electrode (SHE) values.
- Hydrogen ion concentration as pH.
Standing Water Level
At the ground’s surface monitoring, wells are located inside a metal pipe at the surface for protection. The well itself consists of a pvc pipe usually 50 mm or bigger with holes or slots in the area of the aquifer being monitored. Standing water level is the distance between the top of the metal pipe and the water inside the well. The top of the metal pipe has a surveyed reference point that allows the sampler to convert the water level in the well to an AHD data point. This is an important measurement for hydrogeographic assessment of the direction of movement of groundwater. Measuring the height in one well and comparing it to other wells permits geologists to define the movement of water.
CEM identified errors related to Standing Water Level in the TfNSW data including measurements made without a reference point and extreme variation. For well LDS-BH-3090, the measurement from the top of the well casing was reported and the standing water level was not calculated between February 2022 to June 2023.
Most wells showed a water level variation of about 5 metres, which is unusually large. The monitoring wells with the greatest difference between the lowest and highest during the period monitored are shown below.
Standard Water Level AHD
LDS-BH-3087 36.4 m
LDS-BH-3088 28.4 m
LDS-GW-MW3 13.6 m
WCX-BH157A 27.7 m
LDS-BH-3907A 13.7 m
It is clearly not possible for any ground water table height difference to vary by over 36 metres in the time period monitored. This height is equivalent to a building 15 storeys high. These inaccuracies in measuring the standing water level make it impossible to monitor groundwater flow direction over time.
Electrical conductivity
Electrical conductivity is a measure of the capability of water to pass an electrical current. This is a function of its salt content. The higher the dissolved salts the higher the conductivity. One of the most significant errors made by the TfNSW samplers with respect to electrical conductivity indicate a complete misunderstanding of instrumental sensitivity. The best conductivity measurements in the world’s research laboratories struggle to report with accuracy between 3 and 4 significant digits. The instruments used to measure conductivity in the field are simple but robust meters usually capable of accurately measuring 2 significant digits. Reporting electrical conductivity to 5 significant digits as was done in March 2024 at LDS-BH-3087 to 16,138 µS/cm shows a complete lack of understanding of measurement principles. Reporting a value like 16,138 µS/cm infers that the instrument can discriminate between 16,137 and 16,139 µS/cm which is not possible. Having regard for instrument sensitivity this measurement would have been more correctly reported as 16,000 µS/cm. Every single electrical conductivity measurement demonstrated that the person reporting the measurement and everyone reviewing it before publication lacks specific instrumental expertise.
The electrical conductivity measurements for well LDS-BH-3059B ranged from 7,450 to 392 µS/cm. That is nearly a 20-fold difference in conductivity measurements in a groundwater monitoring well.
Some of these values are clearly mistaken.
Redox state of Groundwater
The redox state of groundwater—whether the groundwater is oxic (oxidised) or anoxic (reduced) has profound implications for groundwater quality including the type and transport of contaminants. Leachate is an anoxic, reducing environment. The presence of high ammonia concentrations in near neutral pH indicates that the redox potential measured as the standard hydrogen electrode would always be a highly negative value. Since there are so many positive results, TfNSW’s environmental consultants are obviously doing something wrong when measuring redox. They have reported many positive leachate values with one as high as 630 mv when ammonia (a reduced chemical species) was reported at 180 mg/L. This shows a complete lack of understanding on how this measurement is made. The rest of the redox measurements in the groundwater monitoring wells appear to have been produced by a random number generator. Like all other measured parameters, redox should be stable between successive measurements. Great differences in negative and positive mv readings from the same monitoring well indicates a measurement problem. The same well showed variations between 123 mv to – 199 mv (LDS-BH-3089). It seems that different people using different meters were making random mv measurements without adjusting to the standard hydrogen electrode value as required in Approved Methods for the Sampling and Analysis of Water Pollutants in NSW (2022).
The NSW EPA was specifically asked in an email about redox variability. The statement emailed to them was, “The agreement between successive Redox measurements is the most variable. Can the EPA confirm that TfNSW’s sampling contractors are reporting as the Standard Hydrogen Electrode Eh values rather than random mv measurements ?” The EPA replied, “Redox potential readings are recorded in the field and are reported in millivolts”. This statement indicates that the NSW EPA team member who prepared the reply was unaware of the redox measurement requirements from their own guidelines.
pH is a log 10 measurement of the hydrogen ion concentration. This means that every unit difference represents a ten-fold difference in concentration. Like every other measurement made on site the pH testing showed extremely high variation. The two wells with the greatest variation were WCX- BH157A and MW4D, with values from 5.09 to 7.39 pH units and 5.88 to 8.69 pH units, respectively. This is a variation of 30 times the hydrogen ion concentration and not possible in a single monitoring well under static conditions.
Measurement errors were not the only mistakes made by TfNSW’s environmental consultants. They also reported the exact same results site measurement results (conductivity, pH, redox and temperature) for the leachate sample taken on 15 December 2022 and 21 March 2023. This mistake was missed by the consultant’s supervising manager, TfNSW’s Senior Manager Assurance and Performance Improvement, Environment and Sustainability Branch and the NSW EPA Unit Head of Operations responsible for ensuring Environmental Licence Monitoring conditions are correctly undertaken. TfNSW does not have an exemption to not measure any parameter within the quarter sampling period. If a measurement is missed on the day of sampling, TfNSW are required to reschedule a site visit and measure the missed parameter. In the October 2020 quarter the consultants failed to measure standing water level at LDS-GW-MW3. Additionally, they did not report redox values at LDS-BH-3087 in the September 2023 quarter. They failed to take any of the required quarterly samples in all eleven wells and leachate during the September 2023 quarter. The NSW EPA did not provide any response when asked what actions were taken when these violations were identified, except their patented “we have regular meetings with TfNSW” reply.
The sample for LDS-BH-3089 and LDS-GW-MW3 in the September 2021 and February 2022 quarters due to Hydrosleve (groundwater sampling device) failures were also missed. These wells were never resampled.
The environmental consultant is required to deliver the samples to a laboratory accredited by the National Association of Testing Authorities (NATA) for chemical testing with documentation
concerning sample integrity and testing requirements. The quarterly chemical tests were not reported from the leachate sample taken on 15 December 2022. Laboratory chain of custody error was the reason given for this violation.
Laboratory Testing Responsibilities
Chemical testing is divided into quarterly and annual testing. Quarterly testing is for general water quality indicators. Annual testing is concerned with the analysis and reporting of organic contaminates and heavy metals.
CEM repeatedly asked TfNSW and NSW EPA for the public reporting of annual monitoring testing results from 2021 to 2023. They did not report any annual testing on its internet reporting site until after 4 February 2024 when they reported the results from the September 2023 sampling. They then reported the September 2022 results after 2 June 2024. These latest annual testing results reported did not include any organophosphorus pesticide analysis as required by the licence.
Laboratory test results show the same level of variability as the site monitoring measurements.
Both alkalinity and bicarbonate are required to be tested. Alkalinity is a titration and bicarbonate is a calculation based on the alkalinity result. Examples of alkalinity variation include samples from well LDS-BH-3087 and LDS-BH-3089A where the range was 570 to 4,300 and 370 to 4,790 mg/L CaCO 3 , respectively. That is a variation of 12 times the lower concentration which could not occur in the groundwater. Bicarbonate is calculated by taking the alkalinity result and multiplying it by 1.22 from the alkalinity result to account for the conversion of CaCO3 to HCO3– The bicarbonate results reported from December 2020 to March 2022 were erroneous because the laboratory did not conduct this conversion. Bicarbonate was only reported 3 times in the 9 quarters between May 2022 and June 2024.
Well MW4D had some of the greatest variation in chemical testing results. Chloride ranged from 2.4 to 2000 mg/L, ammonia ranged from 0.03 to 2.2 mg/L and sulphate ranged from 2.8 to 110 mg/L.
Well LDS-BH-3097A showed extreme variation with total organic carbon ranging from 2.3 to 57 mg/L. None of this variation is likely in a single well. There are clearly sampling and/or analytical errors accounting for these differences.
All total nitrogen results reported were erroneous. Total Nitrogen is the sum of all nitrogen forms or:Total Nitrogen = Ammonia Nitrogen (NH3 ) + Organic Nitrogen (Nitrogen in amino acids and proteins) + Nitrite (NO2 ) + Nitrate (NO3 ). Every total nitrogen reported by TfNSW is incorrect. Since the values that were reported as total nitrogen were small in magnitude and seemingly not related to nitrogen measurements, it is not clear what the consultants intended them to represent.
NATA accredited laboratories generally check the analyses’ correctness as a quality assurance protocol before reporting results. These are simple calculations to ensure that the data is accurate before releasing them to their customers. Following these checks, laboratories can reanalyse samples if they don’t meet accepted quality standards which ensures that only correct results are reported.
The common checks include ionic balance, total dissolved solids-conductivity ratios and measured total dissolved solids comparisons with calculated total dissolved solids. The ionic balance is a check on the difference between positive ions and negative ions in solution divided by the mean of all ions.
The acceptance criteria for this calculation are less than 5%. The relationship between total dissolved solids and conductivity is that the ratio must be between 0.55 and 0.7. The target percentage ratio between calculated total dissolved solids and measured total dissolved solids must be between 75 and 125 %. These checks are found in Standard Methods for the Analysis of Water and Wastewater (2023) and specified as mandatory for licence reporting in NSW EPA’s Approved Methods for the Sampling and Analysis of Water Pollutants in NSW (2022).
The ionic balance failed in 9 out of 10 leachate and 63 out of 107 groundwater checks. The total dissolved solids-conductivity check failed in 4 out of 10 leachate and 41 out of 105 groundwater comparisons. The calculated total dissolved solids to measured total dissolved solids ratio failed in 8 out of 10 leachate and 43 out of 107 ground water comparisons. Normally, a NATA accredited laboratory would not report any of these results. If there are quality control failures following reanalysis, the laboratory would provide an explanation for the failure. None of these results should have been reported without an explanation.
Conclusions
- an alarming level of incompetence has implications for not only the regulation of St Peters Interchange but also potentially for the quality of all such monitoring in NSW. Until EPA and TfNSW provide an explanation of the errors, it is not possible to reach conclusions about the broader implications.
- Lack of adequate technical review is the only reason that this level of incompetence could have been publicly reported. The environmental consultants and TfNSW’s environmental management teams did not assess the information before reporting it to the NSW EPA. Nor can it be understood why an NSW EPA Unit Head or other manager did not take any action against TfNSW for not meeting so many of the monitoring requirements from their Environmental Protection Licence. Instead of taking action, the EPA has allowed the poor quality monitoring to continue over an extended period.
- The Environmental Guidelines: Solid Waste Landfill (2016) have provisions for reducing monitoring requirements after five years of solid reporting if that indicates everything is under control. Given the poor quality of the reporting, monitoring requirements should be continued for at least five years from now.
- It is recommended that the environmental consultant company and contracted laboratory be jointly audited by appropriate NSW EPA officers and a qualified water chemistry/sampling NATA Technical Assessor to determine the full extent of errors in this monitoring program. This review would include an evaluation of all chains of custody, calibrations, certificates, calculations, staff training records and analytical quality control data.