Gas Testing at North Head / Maungauika

Gas Testing at North Head / Maungauika

Gas testing has been a major part of the investigation into deteriorating ammunition under North Head / Maungauika. Toxic and explosive gas (toluene and naphthalene) was detected during the original 1992-94 DOC investigation, and is still detected when testing occurs.

Thanks almost entirely to the efforts of Martin Butler and his research while writing Tunnel Vision, testing continues to this day (at least when Martin gives them a nudge about it).

  1. Why is gas testing at North Head / Maungauika necessary?
  2. So what happened with the updated gas testing?
  3. If it's dangerous, shouldn't we leave it alone?

The below was edited together from Martin's own writings and therefore is presented in first person.

It took between 2015-2017 for DOC to agree that gas testing was required at North Head / Maungauika as a result of toxic and explosive gas still emanating from the summit gun pit. However, DOC then reneged on an agreement with me that the gas testing would conclusively determine the source of the gas.

Since that time, DOC, on behalf of the Tūpuna Maunga Authority, have conducted regular gas testing, but only on the assumed basis (without scientific evidence) that the gas is coming from coal tar (used to waterproof the tunnel walls) — rather than deteriorating ammunition.

Since 2017, we have legally ‘compelled’ DOC to conduct semi-regular gas testing at the summit gun-pit. The results of the gas testing to date are cause for concern.

On 21 December 2016 we sent a letter to the Director General of the Department of Conservation (DOC) through a lawyer (who was also concerned) about the nature of the toxic and explosive gas emanating from the summit gun battery that had not been monitored or retested since 1992. This letter demonstrated that DOC was in breach of its obligations under The Health and Safety at Work Act 2015. DOC head office accepted that assessment and directed the Auckland office to rectify the situation.

This led to further meetings with the DOC Auckland operations manager and protocols were established whereby the manager at North Head was directed to engage a company to conduct gas testing at the summit gun pit. I was to be party to discussions and consultation.

Why is gas testing at North Head / Maungauika necessary?

When you walk underground at the summit gun pit there is a strong smell of naphthalene during a warm day. This is the smell of mothballs (for those of you old enough to appreciate that). When tested during the 1992 DOC investigation, it was revealed that there were two components in the gas: naphthalene and toluene.

Naphthalene can be found in coal tar, gasoline/diesel fuels, and explosives. Toluene is a colourless, water-insoluble liquid used in a variety of products from nail polish to, you guessed it—explosives (TNT). It should be noted, however, that these gasses can also come from other coal-related or petroleum-based products.

David Veart, the DOC Chief Investigator of their "once and for all investigation" in the 1990's, dismissed this gas testing result at the time. He concluded that the gas came from 'coal tar' that was used to water-proof the tunnel walls of the 1870s summit gun pit.

In fact, two chemists later argued the results in court. One saying coal tar was the source of the gas, and the other saying that the combination of gasses present emanated from deteriorating ammunition. The court case presided over by New Zealand's Chief Justice, Sian Elias found 'on balance of probability' that the gas came from the coal tar. The reason for this determination was DOC’s failure to find any tunnels during their 1992-94 investigation. The Chief Justice concluded that there were no tunnels, and therefore there could not be ammunition within them.

Coincidentally, DOC’s evidence also led to some 60 affidavits and eyewitness accounts being summarily discounted. These affidavits were from people who largely said they had been inside the sealed tunnels.

In researching the book Tunnel Vision I became concerned about the conclusion reached about the gas testing for five reasons:

  1. The gas testing was also conducted at the 'Engine Room', (another site that was built at the same time as the summit gun pit). However, the engine room was the only place where a coal tar sample was taken from, and it yielded only naphthalene and not toluene. This was therefore inconsistent with the summit gas test result.
  2. The naphthalene and toluene gas was identified in different locations at the summit gun pit.This seemed illogical. Surely if both gasses came from coal tar, it would occur at the same sites and be evenly distributed throughout the gun pit (and engine room).
  3. Strangely the highest concentration of gas was from an area 2 metres in front of the summit gun pit, in soil—well away from the areas where coal tar was used.
  4. The DOC Independent Engineer Report from 'Riley Consultants' stated that the source of the gas could be from deteriorating ammunition in sealed tunnels beneath the summit gun pit.
  5. The smell of naphthalene gas on North Head / Maungauika gets stronger as the temperature increases throughout the day. This seems to be at odds with the coal tar theory. After 147 years it seems strange that the coal tar would still be producing varying amounts of gas dependent upon the temperature.

So what happened with the updated gas testing?

Unfortunately the DOC management (at that time) decided to exclude me from further meetings, however, the summit gun pit location was gas tested over the 2017 summer period.

When I finally received a copy of the gas testing report in March 2017, it was apparent that the parameters of the initial proposed gas testing had been reduced due to cost. But it still revealed that toxic and explosive gas now described as Volatile Organic Compounds (VOC) is leaking from the summit gun pit. What's more, the source of the gas is still unconfirmed as being from coal tar.

After further correspondence a meeting with DOC's Auckland operations manager revealed that a manager had been appointed to conduct a health and safety investigation. Up to this point in time, DOC had steadfastly refused my requests for a health & safety investigation of North Head / Maungauika despite the evidence I had provided over the years, much of which is included in ‘Tunnel Vision Refocused’.

A further meeting was held with the appointed manager some months later and resulted in agreement that the implications of there being deteriorating munitions at North Head would also be considered as part of the health and safety review. This task was later assigned to the gas testing consultants.

On 8 August (2017) I was invited to a meeting to discuss the health and safety findings to date, including the gas testing results with the consultants engaged for that purpose.

At that meeting, it was agreed that further gas testing would take place at some specific locations and that this would be conducted when seasonal air temperatures increased (due to concerns I had about the effect of ambient temperature). I also provided reference materials on the various types of munitions that may exist if underground magazines are located at North Head / Maungauika.

If it's dangerous, shouldn't we leave it alone?

The fallacy that ‘if ammunition exists - it is best left alone’ was also discussed at the meeting outlined above. It also seems to be a commonly held misconception that munitions will only explode if one of the 3 ‘fire triangle’ elements change i.e. air, fuel, or ignition source. For example, if you now introduce air to a sealed area it may cause an explosion.

However, this is a dangerous and inaccurate misconception. The evidence I provided at this meeting showed that as Munitions and Explosives of Concern (MEC) age, the explosive compound in MEC items can remain viable and could even increase in sensitivity.

A number of the munitions known to be at North Head (during its military history) also contained unstable chemicals such as picric acid. Deteriorating ammunition may detonate at any time due to chemical reaction. They do not need the introduction or presence of air or other ‘fire triangle’ elements to initiate an explosion.

Detonation of decaying ammunition may occur due to any number of factors. For example, such things as impurities in the manufacturing process, sensitivity, a chemical breakdown of the source products used, corrosion or being in contact with a non-compatible element. In addition there could be leaching of explosives into the soil called 'explosive soil'. Deteriorated MEC can present serious explosive hazards, regardless of environment.

Consequently, the 'Tunnel Vision’ team position has been made clear to DOC. There could be all forms of munitions of both British and American manufacture, conventional and chemical. If ammunition exists at North Head / Maungauika, it needs to be properly assessed to determine its condition and the best method of disposal.

Leaving deteriorating ammunition to deteriorate further is not the safest course of action, but it may rank as one of the stupidest. That is why every location of a possible tunnel entry identified at North Head / Maungauika by the Tunnel Vision survey requires further investigation.

One objective by DOC is to ensure that the gas at the summit does not pose a risk to Health and Safety from breathing the fumes in. Our objective is to positively identify the source of the gas (as was an original gas testing objective). Simply determining that breathing the gas does not pose an immediate health risk to people will not (in our opinion) enable DOC to conclude its investigation for the following reasons.

  1. If the source of the VOC gas emanating from the summit of North Head is conclusively determined to be from deteriorating ammunition, it would not limit the geographic location of the ammunition to the summit of North Head. The gas could be coming from open or closed tunnels beneath the gun pit as described in the DOC consultant ‘Riley Report’ of 1992. Conversely, if the source of the gas turns out to be other than explosives, it would not mean that explosives do not exist at other locations on the hill.
  2. Significantly, the ground penetrating radar and photographic evidence has now been accepted by DOC as credible evidence of sealed tunnels at North Head / Maungauika. This in itself was a major breakthrough as it reversed DOC’s 1992 position - that no tunnels exist at North Head / Maungauika other than those you can see today!
  3. With the acceptance by DOC that sealed tunnels may exist, the Health and Safety Review must also now consider credible eye witness accounts of deteriorating ammunition in sealed tunnels at North Head / Maungauika including the Tizard recording.
  4. Gas testing to date has been extremely limited in scope (only 2 locations) on North Head / Maungauika. DOC’s acceptance of our ground penetrating radar survey results strengthen our position that the Health and Safety Legislation requires investigation of all the sites we have identified for sealed tunnels. If sealed tunnels are found, they need to be gas tested prior to entry. Any sealed tunnels must be fully explored to ensure deteriorating ammunition does not exist. We have offered to do this free of charge, in compliance with the regulations and with appropriately qualified personnel.

The good news is that we know (down to the centimetre) where to drill the holes for gas testing and camera investigation. We are not and have never espoused a position of just randomly digging up North Head / Maungauika. Such a proposition would be contrary to cultural sensitivities and historic site considerations. But the balance between those considerations and the safety implications must now be directly addressed by DOC’s health and safety review.

Back to blog

Leave a comment

Please note, comments need to be approved before they are published.