September quarter 2024 review of TfNSW monitoring results by CEM research director Charlie Pierce
This is the area that was supposed to be delivered to the community as a public park in 2021. It contains a lot of old contaminated waste for the Alexandria Landfill and the remains contaminated. Photo by CEM :2024
Background
Transport for NSW (TfNSW) are required to monitor
groundwater, leachate and methane at the St Peters
Interchange Landfill to comply with an Environment
Protection Licence (4627) issued by NSW Environment
Protection Authority (EPA).
TfNSW contracted WSP environmental consultants to conduct the sampling and field testing. WSP contracted SGS Australia Pty Ltd Environmental Services – Sydney Laboratory to conduct the analytical laboratory testing of ground water and leachate.
Current situation
Community Environmental Monitoring Pty Ltd (CEM) has previously reviewed this test data two times (https://pollutionwatch.org.au/2024/10/westconnex-st-peters-interchange-environmental-mon
itoring-failures/ and https://pollutionwatch.org.au/2024/02/report-st-peters-interchange/) and found that it was not fit for purpose. CEM’s review identified numerous field sampling mistakes coupled
with laboratory errors which meant that the monitoring results from 2020 to 2024 unusable to assess groundwater conditions.
CEM meetings with EPA
Since that time, CEM representatives met with the EPA twice to discuss their level of understanding of the monitoring data quality. We also wanted to find out why the licence holder had not been issued any penalty notices for the hundreds of errors made during the 4-year monitoring program. CEM also requested that the EPA provide us with copies of the Site Auditors Reports.
The EPA’s response has been to say that they routinely meet with the Licence Holder and the Site Auditor to discuss these issues. They also reported that the Site Auditor reports would
not be available until some time in the future. However, we believe that the Site Auditor issues annual reports on the monitoring program along with special assessments of plans to
modify the program including the recent modifications to the gas monitoring program.
CEM meets with TfNSW
In January 2025, the CEM team met with three TfNSW’s staff (including a Community Engagement officer, a Media Liaison officer and St Peters Interchange Project officer), a TfNSW Sustainability Manager and Chris Jewell, the Site Auditor, in January 2025. During this meeting we highlighted the apparent lack of technical oversight and absence of a quality assurance
program for the groundwater, leachate and gas monitoring programs. There was general agreement that there have been some errors with monitoring data.
TfNSW staff explained the monitoring errors by pointing out that the sampling consultants were only permitted to sample at night and for only a few days each month. This is why they haven’t been able to resample when they miss sampling or have a failure in getting samples analysed.
TfNSW’s Site Auditor also explained that the negative hydraulic gradient created by pumping leachate ensured that the movement of any contaminants off site was not likely due to the negative hydraulic gradient.
September Monitoring Results
The September Quarter monitoring results were released, CEM again reviewed the data, partly to determine if the EPA’s communication with the licensee had resulted in any noticeable improvement in the monitoring program’s
quality assurance.
Gas Monitoring
Methane monitoring results were complete except for one gas monitoring well (LDS-GM-022A) ostensibly destroyed during Gateway Construction. Four wells were reported to have initial gas concentrations exceeding 100 % (summation of reported gases)
which is not possible. These wells were LDS-GM-028 (115.3 %), LDS-GV-48 (112.5%), LDS-GV-49 (105.1) and LDS-GV050 (107.6).
It is interesting to note that the carbon monoxide concentration increased from 7 – 11 percent at LDS-GM-0009D to 30 ppm. Carbon monoxide is an indicator of combustion. This is
normally not a concern until it is greater than 100 ppm but worth watching.
Leachate Monitoring
The leachate monitoring results are more stable than most of the groundwater data. The measured standing water level, ammonia nitrogen, chloride, calcium are essentially the same as the long-term mean. This may directly refute the claim that draw down from the leachate creating a negative groundwater gradient is responsible for the high variability in
groundwater test results.
The leachate monitoring parameter which appears to be unreliable is redox potential. It is unlikely that the redox potential measured as the standard hydrogen electrode in millivolts would be positive when the measured ammonia (a reduced species) was elevated at 210 mg/L.
Groundwater Monitoring
Well development
Groundwater monitoring well 3057 (B) was finally replaced after being out of action for more than a year. Unfortunately, the team that installed the well did not properly develop the well following installation. Well development refers to the process of cleaning out drilling fluids that inhibit water flow within the well so that groundwater could freely flow. The water chemistry in well 3057 (B) is representative of concrete and/or bentonite used during
installation rather than local groundwater. The high pH and low salt content reflect well construction activities and not groundwater conditions. None of the chemical water measurements in this quarter may be considered to be reliable. The best course of action would be for TfNSW to publicly declare these measurements are worthless and must be removed from the data set.
Quality Assurance Checks
It may seem tedious to highlight the potential errors in measurements made during the Sept 2024 sampling quarter. However, it is important to continue to document the lack of any
quality assurance for the groundwater monitoring program at the St Peters Interchange (Landfill).
There are three common data quality checks most NATA accredited laboratories perform when testing aqueous samples. These include ionic balance, total dissolved solids
(TDS)-conductivity ratios and measured TDS comparisons with calculated TDS ratio.
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).
This review reports these quality control failures on a total basis rather than enumerating them individually. There were 17 failed quality checks out of 27 possible comparisons measurements (63 %). It is highly unusual that any accredited laboratory could have such a high error rate.
Other Errors
The phosphorus (PO4-P), Hydrocarbons and zinc measurements for well 3059 (B) sampled in September 2024 appear to be in error. All of these parameters were reported to be much
higher than the long-term averages.
The reported redox potential for well 3059 B appears too low with a report at -67 millivolts when the ammonia was 6 and mg/L and the sulphate (oxidised anion) was 720 mg/L.
TfNSW has acknowledged that the electrical conductivity measurement for well 3088 and MW3 were incorrect. The reported value was 517 μS/cm and the long-term average is 5,230
μS/cm at well 3088. The conductivity value for MW3 was reported to be 8,844 μS/cm with a long term average of 15,000 μS/cm.
The phosphorus (PO4-P) result at 1.9 mg/L for well 3088 seems erroneous since most recent measurements are less than 0.6 mg/L.
The alkalinity measurement in well 3091 appears to be erroneously high. The September 2024 measurement was 670 mg/L compared to a long-term average of 490 mg/L. Likewise the chloride measurement seems low in well 3091 at 89 mg/L compared to the average of 120 mg/L.
The person sampling at monitoring wells MW3 and 3907A failed to get the samples to the laboratory fast enough for analysis for ammonia, nitrate, nitrite, phosphorus and total organic carbon. The holding time for these tests was exceeded before measurements could be made. This mistake caused the loss of 10 required measurements in this quarter. It is understood that WSP did not have access to the site to arrange for additional sampling during the entire quarter due to these wells being located on land controlled by Transurban.
The redox potential for MW3 seems too low at -40.9μS/cm when the sulphate was found to be 2,000 mg/L.
The ammonia measurement for well BH157A seems incorrect. It was reported as 29 mg/L when the long-term average is 3.4 mg/L.
Reporting Significant Digits
Good laboratory practice requires that the number of significant digits quoted in a result shall not imply a degree of precision greater than that warranted by the sources of uncertainty. The
number of significant digits is meant to reflect the sensitivity of a test result; consequently results on a test report that contain more significant figures by inference would be considered
more accurate. Quoting to more significant figures misrepresents the degree of calculated precision and may lead to unfounded concern when guidelines are exceeded at the level of
the extra significant digit. As a general guideline, the results obtained from the majority of chemical tests should be reported to two significant figures; however there are exceptions
depending on the test equipment and calibration procedures.
Field meters used for measuring parameters may be characterised as robust but relatively insensitive measuring devices. A field pH meter could not be sensitive to more than 2 significant digits. To report pH to 3 significant digits would require a high-quality
experimental meter with the measurements being made in a controlled environment. That is not the case when measurements are made in the field at a landfill. WSP have routinely reported pH to 3 or 4 significant digits.
Likewise a field electrical conductivity meter is characterised by limited precision. It is not possible for a field meter to report to 4 significant digits. Reporting at this level would infer that the meter could measure the difference between 1,214 μS/cm vs 1,216 μS/cm which is well beyond the analytical precision of the field instruments used for these measurements.
In most cases where CEM identified a rudimentary error in reporting data to EPA and TfNSW, there was a noticeable improvement in performance. For instance, there hasn’t been
an error in reporting bicarbonate concentrations for more than a year after successive years of errors. Once we reported that they were making a fundamental error, they stopped making
this error. However, the incorrect reporting of too many digits is still happening after we reported this poor practice last year.
CEM’s Quality Assessment of September 2024 Monitoring
WSP are TfNSW environmental consultants responsible for meeting the monitoring requirements found in Environmental Protection Licence 4627. This review of the September
2024 sampling found that there were errors in methane monitoring, leachate monitoring and groundwater monitoring. Errors were found in 63 % of simple laboratory quality control
checks specified in method references. One well wasn’t even developed following installation, making all reported measurements suspicious because the results were not
characteristic of the local groundwater. Two wells had measurements that could not be tested due to holding time errors made by an apparently inexperienced sampling technician ostensibly operating without supervision in a program lacking quality assurance.
The measurement variability between samples at each well is large. That makes it nearly impossible to find errors. Even so, this evaluation found 8 possible analytical errors based on chemical signature or historical trend.
These facts taken together continue to indicate that there is very little assessment on the quality of the data by WSP or TfNSW scientific staff before it is reported. To address this deficiency, it is recommended that the EPA audit the sampling and split samples so that an accredited government laboratory (EPA, Sydney Water, Water NSW or the National Measurement Institute) could test these samples. This sort of assessment will enable a more
informed assessment on the quality of the results from this monitoring.
The monitoring program is required by legislation and is paid for using taxes. The public deserves to have the monitoring performed following international best practice instead of
current practice.
St Peters Westconnex Interchange 2024 – looking across to Mascot apartments– CEM photo 2024