HPVs – The leaking gas industry infrastructure that is being kept secret

Co-authored by Shay Dougall – Molliwell and Johanna Evans – NWPA

What is a high point vent (HPV)?

Gas and water is extracted from the coal seam via the gas well. The gas and water are separated at the well head and are transported in separate buried high-density polyethylene (HDPE) pipelines to the gas processing facility.  Some water will be present in the gas pipeline which will block the gas flow if it is not allowed to drop out of the pipeline via a low point drain.  Some gas will be present in the water pipeline and will cause a vapour lock and prevent the water from flowing if it is not allowed to be vented off at high points vents (HPVs) along the pipeline (the vents also mitigate the risk of potential vacuum formation due to the downward sloping of some of the water pipelines).   

The HPVs are made of varying designs, and as time has passed, there has been some improvement in the designs. However, there are many HPVs across the massive network of thousands of kilometres of gas gathering systems across the Western Downs that are fundamentally designed to release gas and occasionally, raw coal seam gas (CSG) water and coal fines.  Although HPVs are not designed to release large quantities of gas over long periods of time, there is little in their design that enables this to be proactively managed, and there is evidence gathered by residents living among the infrastructure that this is exactly what occurs (see video below).

In fact, in the AGPA Code of Practice for leak management, detection and reporting for petroleum operating plants – a reportable leak is defined as: For high point vents on gathering systems – A release from a high point vent that is continuously releasing gas for an extended period of time.

While the theory behind the existence and operation of the HPVs have been given consideration in terms of the operational needs of the gas industry, their impacts on the rural community required to live with the operation are not given consideration. This is clearly demonstrated by the following extract from the AGPA Code of Practice -Upstream Polyethylene Gathering Networks – CSG Industry:

Vents on CSG water pipes shall be used in rural locations only, and should be located a minimum of 100m away from the property line of rural-residential and residential areas. Vents on CSG water networks shall be designed to vent intermittently.

The DNRME recently audited the industry against this code of practice, the results of this audit are only available via RTI at a cost of hundreds of dollars. A review of the data released under RTI identifies that the Department and the industry are aware of the community concern over these pieces of infrastructure and that the regulatory management of them is inadequate as can be seen via this extract:

 “the audit teams discussed at length the issue with respect to the other frequent landowner complaints of continual venting HPV’s… and strongly indicated frequency of inspection be reviewed…”


An example of the potential density and cumulative impacts of HPVs laid across the rural community is: in an area of 2.8km radius of one farmer’s home and business, that there is approximately 87 points of emission.

These vents have two issues of concern associated with them.

  • HPVs are designed to release unmonitored and unmeasured amounts of gas into the atmosphere;
    The gases released from the HPVs have been tested by community and once as a result of complaints by residents by the government. The results of this testing showed that some of the chemicals present in the HPV releases are: Propane, acetone, ethanol, 2-Propanal, Carbon Disulphide, Hexane, Cyclohexane, Heptane, Toluene, Ethylbenzene, M&P Xylenes, o-xylene and methane. Independent testing was conducted on a vent near Chinchilla. It showed methane (CH4) reaching up to 80%. This is above the lower explosive limit for CH4.

The government and industry insist that this is not a problem for the local area since the main gas (methane) is lighter than air and will dissipate quickly.  But again, that perspective fails to consider the cumulative effect of many HPVs surrounding the home and workplace for the farmer. And that the actual amounts of emissions have never been modelled or otherwise assessed, so this claim cannot be confirmed.

  • HPVs are designed to leak raw CSG Water
    Many HPVs are designed to operate with raw CSG water being released through tubing directly to the ground and when they fail, can be releasing large amounts of raw CSG water to the surrounding area.
    These HPVs may be fenced, but the ground within the fenced area is still the farmer’s land and is still connected to the rest of the property.  Therefore, what ever falls out of the infrastructure to the atmosphere or to the ground has the potential to impact the farmer, his staff and his operation.
    For example, even if the amount of raw CSG water allowed to be discharged by the tubing on the HPV built into its design is released at an approximate rate of 0.5L/min, that will amount to 720 litres per day (which is an annual leakage rate of 262,800 litres).
    CSG water can be very salty and can contain trace elements of other chemicals.  It has not been treated and is straight from the gas well, so it has not been tested, its quality is unknown.
    There have been multiple incidents of failures of HPVs across the Western Downs, and no doubt many more that have gone unrecorded.
A leaking high point vent in a paddock with stock

The entire means of considering and assessing the role and risk from HPVs in the permitting of the CSG industry has been inadequate.

  • HPVs are not listed in the P&G Act,
  • they are not listed and assessed in Environmental impact statements,
  • they are not given compliance parameters in the environmental authorities,
  • their emissions are not required to be reported or mitigated in any way,
  • they have not been assessed for bushfire risk,
  • virtually no information is available on exactly what emissions and contaminants are released to air and ground,
  • their number and location are not listed in public information such as Qld Globe.

The philosophy built into this engineering design is that venting is an acceptable practice when in reality, the overwhelming direction of operating philosophy in modern industry is to have an entirely closed system, and to have zero leaks to ground/atmosphere. Looking at the cost of gas this is also counter intuitive as the recovery of the emissions should be priority for the industry to ensure the most benefit out of the extraction process. But as we know, the profit margins for this industry are such that the cheapest approach is the preference, and those who bear the burden of these financial decisions are of course those expected to live with the industry and its cumulative impacts.

HPVs are gas vents, they are considered secondary infrastructure. They are essential to the operation of the gas companies waste/water gathering systems for gas extraction and there are thousands of them throughout the Queensland gasfields. It is likely the regulators do not know how many there are.

Queensland Health has failed to provide community with a Health Impact Assessment to provide surety to those required to host the industry that these vents are safe and non-harmful to humans and livestock. Successive Ministers have failed to commission any studies on the various health risks and impacts from the mining of unconventional gas.

Click to see our HPV & LPD Flickr album

One manufacturer of the vents ‘Focus Valves’ describes the purpose of their product “designed in collaboration with the CSG Industry to address unique operating requirements and completely resolve the issues experienced with existing valve technology. They are used to de-gas water pipelines in gathering networks and at well head skids.” Another, Vent Master, says it’s product is the “valve of choice in Australia due to its large venting capacity and corrosion-resistant properties”.

When examining gasfield emissions in 2014, the CSIRO found that a gas relief vent on a water gathering installation was a larger source of methane than the well pads they sampled. It’s unlikely that this is an isolated measurement as this is exactly the job the vents are purposed for.

Excerpt from CSIRO report

For every kilometre of wastewater pipeline there can be 2-3 vents or more depending on what other infrastructure is connected. With no meaningful studies completed on the cumulative impact of these substances (don’t forget vents are replicated thousands of times) how is safety for residents and landholders living amongst gas company infrastructure assured?

Lack of information is worrying

There is no gas company nomenclature or literature available to the public that lists the spatial frequency and risk potentials of high point vents in the Queensland Gas Fields. These pieces of infrastructure are adjacent to high pressure gas pipelines that traverse the landscape in the gas fields. This infrastructure is frequently installed in rural/residential areas effectively turning homes and farms into hazardous industrial areas. Their installation is usually accompanied by DANGER signage.

There is no official total of just how many HPVs there are. There are thousands of kilometres of pipeline so we can assume that there are thousands of these toxic vents. The government regulators have no idea about the cumulative emissions that are emitted from these HPV’s and they are not reported on by any of the companies.

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