Increased testing and a detailed study are helping Port Taranaki get a clearer picture of the quality of water in the harbour.
As part of its stormwater discharge consent with regulator the Taranaki Regional Council, Port Taranaki must ensure that sampled water released into the harbour through its stormwater system falls within limits for total suspended solids (TSS).
TSS are solid, non-dissolved particles in water, including sediment, algae, bacteria, and organic matter, such as log bark and particles.
In recent years, Port Taranaki has installed a number of vortex separator systems in log yards to capture log particles and help clean the water before it enters the harbour.
“The harbour plays an integral role in our community and for our business, so we want to make sure we look after it as best as possible,” says Port Taranaki environmental manager Kevin Lehrke.
“The nature of log yard stormwater means that you can take a sample and get one result and take another sample 10 minutes later and it will be totally different.”
Because of this variance, when applying for its current consent, which was granted in August 2024, Port Taranaki requested some flexibility and for a more scientifically robust sampling and assessment process.
As well as an increased allowable TSS limit, Port Taranaki was permitted to meet the TSS threshold 95% of the time, which is an approach that is consistent with many other ports that handle logs.
“Because the assessment is done statistically, we need to have a whole lot of data to analyse whether we are compliant 95% of the time. So, we are now doing more sampling and testing than has ever been done before – aiming to get 100 TSS results over a 12-month period”.
TRC continues to carry out its own sampling, along with site inspections and auditing of SGS’ testing.
“We provided a stormwater monitoring report to the TRC in September for the past year, and were pleased the report showed our TSS results were within the 95% allowable limit,” says Kevin.
Port Taranaki is also carrying out a study to determine stormwater variability, involving the use of auto sampling machines to take multiple samples throughout rainfall events, from which the port can get an event mean, or average, of TSS.
The data will be used for future consent consideration and to further help protect the harbour.
