Air quality around Sewage treatment plants should be monitored all the time in our view. This should be done to give the community confidence that consent conditions are being meet and so that they can see that problems (that everyone accepts happen from time to time) are managed.
The main indicator to watch for is Hydrogen sulfide. If you have that in the air then you know the other things that are harder to track are likely to be there too.
In Christchurch there was also lots of debate about methyl mercaptan. It’s a lot harder to detect and exists in lower levels.
Christchurch City Council, following lots of community debate, settled on 4 active sites to monitor. Levels are very low for H2S at present. Part of the debate centered around where the testing was done and how. These sites included the local primary school.
Back in January 2024 Christchurch advocates asked CCC for information about how this was done:
Thank you for enquiring about what equipment this Council has used for monitoring Hydrogen Sulphide levels in the vicinity of the Bromley oxidation ponds since the fire. You have referred to Mercaptans but these compounds are not easily measured as they can cause unpleasant odours at much lower levels than can be measured by portable equipment. But, being able to detect the presence of Hydrogen Sulphide, which is produced in the same conditions as Mercaptans, means it is possible that when one is present that the other one may be as well.
Council purchased Acrulog meters from Entec Industries in Auckland, https://www.gasdetectors.co.nz/gas-data-loggers/ . The cost of the meters varies depending on the features each meter has such as data logging, 5G capability and weather shielding. Council purchased meters with a range of features with an average cost of approximately $6K each. However for an up to date cost it would be best to approach Entec Industries directly. Entec Industries also have some of these meters available for hire.
Entec Industries were contacted:
These are the documents they sent us:
https://seaviewstench.co.nz/wp-content/uploads/2024/12/Acrulog-PPM-Brochure.pdf
https://seaviewstench.co.nz/wp-content/uploads/2024/12/Acrulog-H2S-PPB-Brochure.pdf
https://seaviewstench.co.nz/wp-content/uploads/2024/12/Gas-Detector-Rental-Pricing.pdf
https://seaviewstench.co.nz/wp-content/uploads/2024/12/Don-Gould_Quote-_H2S-Loggers.pdf