Bottled Tweed Shire Spring Water - The Biffo!

I’ve been meaning to address the ‘bottled spring water' discussions that have been going on for quite some time in the Northern Rivers. I guess better late than never is OK. The recent request by Tweed Shire Council for comment on their draft planning proposal made me think it was worth putting some ideas up now. This is not a very technical post, more of a bureaucratic process one. Note it does not include surface water issues which are legally very similar and tied up with groundwater, it also does not consider the other issues such as road damage from haulage of water, construction of water supply pipelines etc). To be very clear... this is also tagged as an opinion post. It contains my personal views and opinions on the matter - they can be very different from yours! Feel free to let me know what your opinion is in the comments section below.

Can't find a relevant photo... so this will do!

To give some background, groundwater in the Tweed Valley is derived from two main aquifer types, either deep fractured rocks of the (administratively called the New England Fold Belt Coast Groundwater Source), or shallow groundwater systems of the sediments of recent alluvium (Such as the Tweed Alluvium Water Source). I understand that most (or is it all?) of the groundwater that is extracted in the Tweed Valley that ends up in water bottles is from the deeper groundwater source.

 

Tweed Council is proposing to prohibit new water bottling facilities in rural zoned areas of the shire. One of the reasons overly simplistically outlined for this proposal by the Tweed Daily News is that “there is not enough data on groundwater resources to fully understand the environmental impacts of the industry”. The Planning proposal document also says “…there was a perception that water belongs to the community and should not be used for private profit”.

This raised my eyebrow. 

Access to groundwater in NSW is controlled by the state government. This is in two forms: 

1. 1. The actual well or borehole that is to extract water is licenced by the state. 

When and individual wants to install a bore a water supply works approval application must be made to WaterNSW. Staff experienced in groundwater (including hydrogeologists) assess the application against plans (Water Sharing Plans) that have been developed to protect the environment from badly extracted water, including too much extracted water over periods of time, the possible impact on neighbouring groundwater bores and groundwater dependent ecosystems.  

2. 2.Water is owned by people and companies. The water itself when not used for basic landholder rights (e.g. stock and domestic) is licenced by the state and capped based on the water source (Water Sharing Plans). There is no automatic community right to any water unless it is basic rights water – which the Water Sharing Plans prohibit from being adversely affected. 

If an individual wants to extract water that is not for basic landholder rights they must buy water from some other producer in the water source. This means that the amount of water extracted cannot be increased. The plans that are in place also place a limit on how much water for different uses can be extracted from a source. I think the category of water in the case of bottling water would be Industrial Use. The limits on water have been set by hydrogeologists and state planners and are outlined in the Water Sharing Plans.

Slight differences to the above process are where a development is classed as state significant development, these are assessed in an even more detailed way (and by another organisation – the new Natural Resources Access Regulator). However, even in this case the extraction rules in the Water Sharing Plans cannot be ignored. 

In addition, the NSW Chief Scientist is due to release its final report on the impact of the water bottling industry on the North Coast. Being a state government review conducted by hydrogeologists this review has the potential to be the most useful for decision making and can directly feed into modifying the Water Sharing Plans or other licencing processes if there is shown to be a deficiency.  

Given that water is managed by the state government I was surprised to see that there is an expectation by some that Tweed Council should seek to manage water using local planning instruments. It is interesting that if a bottling plant is proposed in a rural area in the Tweed it requires Council consent now, and concurrence from other environmental agencies. In fact local government is legally required to refer such matters on to the appropriate state government department for these matters.  

I’m not saying this is the wrong way to manage water it is just, in my view, a very novel and creative way given the state has ultimate authority over water resources. How can a local government place rules that stop new water bottling plants to be constructed, but cannot stop water that is legally owed by someone and allowed to be used for that purpose under state rules? I guess this is one way you can… but a very cumbersome and possibly unnecessary way? If there is an expectation that the community owns the water, should the community actually be buying the water? I don’t fully know, as always I have more questions than answers! 

Anyway, the draft proposal in on public exhibition until the 17th of September 2019. Go to www.yoursdaytweed.com.au/waterbottling for more information or to make a submission.

Blog Update #10 - Pain and a paper

Eleanor Faith Holland

The blog has been on hold for a while. But I have always intended to keep on writing. There has been some major changes in where I live and work and most recently our lovely 6 year old daughter Eleanor passed away. There has been much pain but there is much celebration too for our special girl. My wife Becky and I are in feelings of loss. That said, we want to celebrate the life of our daughter who demonstrated so much strength in so many ways. A service will be held at St Peter’s Cathedral in Armidale at 2pm on Monday (19th December).

 

Coming to Christmas it is a subdued feeling at our home and my birthday was yesterday as well so I didn’t feel like celebrating. However, there was something I was excited to see. A confirmation that a paper that I was a co-author of has been accepted to the journal Science of the Total Environment (Santos et al 2016). I was only a minor co-author but there is something about having your name up there that caters for ones ego.

The highlights of the article are:

• We assess groundwater recharge through a pervasive layer of floodplain muds.
• Modelled groundwater flow paths were consistent with tritium dating.
• The clay layer did not prevent recharge because of macropores and cracks.
• Fine-grained floodplain soils do not necessarily protect underlying aquifers from pollution.
• Combining multiple techniques gives more confidence in recharge estimates.

The article can be found here:

 

http://dx.doi.org/10.1016/j.scitotenv.2016.11.181

References

*Santos, I.R., Zhang, C., Maher, D.T., Atkins, M. L. Holland, R. Morgenstern, U & Li, Ling. 2016. Assessing the Recharge of a Coastal Aquifer using Physical Observations, Tritium, Groundwater Chemistry and Modelling, Science of The Total Environment, Available online 15 December 2016, ISSN 0048-9697, http://dx.doi.org/10.1016/j.scitotenv.2016.11.181.

Geology dance moves

I'm moving on from my job hoping for more opportunities in the future. I was disappointed with many aspects of my position, not in the least the resistance from bureaucratic processes to fit in with geological reality! This was particularly disappointing with the search for groundwater resources which I felt seemed encumbered by the processes rather than where water could actually be found. I guess that is government, but it is sad when you feel that the public money your organization is entrusted with is poorly spent. I could have paid for my salary many times over if my advice was taken in the first place. After two years they discovered that exactly what I had said was the case! several hundreds of thousands of dollars later my top two recommendations were identified by expert consultants as the best two recommendations and we hadn't even drilled yet! A lesson for all those people that think they can understand what the environment without actually going out from behind their desk.

So it is with relief that I move on to other things. Time will tell what will happen but in the mean time I might learn some dance moves courtesy of the Amoeba People .

'The Alluvial Fan' is my first starting move:

"We think you'll agree that few things are more dance-inspiring than cone-shaped deposits of sand, gravel and silt."

Baseline CSG methane in groundwater

A friend recently let me know that a paper that one of his students wrote for the Journal of Hydrology had been published. I had a very minor involvement in the formative stages of the paper which came about indirectly as a result of the protests of many local people about potential coal seam gas (CSG) and other natural gas types in the region. The paper (Atkins et al 2015) is essentially the results of a data collection exercise but has some interesting techniques and findings about the baseline concentrations of gas in groundwater bores in the Richmond Valley area.

Methane concentration for different geological environments
(after Atkins et al 2015)

91 water samples were collected from government and private bores in geological units overlying the target CSG geological formations in the Clarence-Moreton Basin (e.g. the Walloon Coal Measures). These units were quite diverse and ranged from sedimentary rocks of the Piora Member of Grafton Formation and the Kangaroo Creek Sandstone (recently reclassified as the Orara Formation), basalt lava flows of the Lismore, Astonville and Kyogle Basalts and Quaternary aged alluvium including coastal sands and riverine sedimentary environments.

Special glass water sample containers were used to collect the samples. These were then injected with a carbon dioxide and methane free gas to create a clean “air bubble”. The methane and carbon dioxide naturally dissolved in the water will then come into equilibrium with the “air bubble”. The resulting gas from the bubble can then be extracted and the concentration and isotopic composition of the carbon in the two compounds determined by an electronic analyser. The isotopic signature can then be assigned to recent biological formation (biogenic) or geologically derived (thermogenic) origin.

The end result was annoyingly quite not straight forward. The concentration of methane showed no obvious relationship to the chemistry of the groundwater. However there was a relationship between geological units. Methane concentration was very low in the basalt aquifers and relatively higher than the Clarence-Moreton basin sedimentary rocks and much higher in the Quaternary alluvium of the Richmond River valley floodplain and coastal sands systems. So there was more methane in some of the aquifers that were the less likely to be connected to any CSG formations! Quite counter-intuitive.

The isotopic signatures did not really help clear up this confusion very much. There appeared to be a large thermogenic component to the coastal sands and flood plain aquifer systems sometimes at concentrations greater than the formations that should be the thermogenic CSG source. Why? It was noted by some CSIRO scientists working in the Great Artesian Basin that sometimes biogenic gas can be oxidised and then be chemically reduced back to methane and this process favours the thermogenic isotopes (Day et al. 2015). So, It gives the impression of thermogenic gas.

This means that the methane gas concentration is related to the biological activity in and around the aquifer. The shallowest groundwater systems are the most connected with surface water and biological processes and therefore these have the highest concentrations of methane. The Clarence-Moreton Basin sediments are not connected with the CSG and natural gas rich formations.

This means that if companies like Metgasco do commence gas operations in the area there is a statistical background that can be used to compare if anyone becomes concerned about methane in their water bores. Interestingly, it also shows that methane in groundwater is probably not a good method to search for natural gas in the region. It might apply to other areas like the Great Artesian basin but apparently there are good barriers between CSG and non-aquifers in the Northern Rivers. This is good news since if something does go wrong it is now more easy to identify if it has impacted upon any groundwater.

References/bibliography:

Atkins, M.L., Santos, I.R. & Maher, D.T. 2015. Groundwater methane in a potential goal seam gas extraction region. Journal of Hydrology: Regional Studies. V4.
Day, S., Ong, C., et al. 2015. Characterisation of regional fluxes of methane in the Surat Basin, Queensland. CSIRO report EP15369

Don't you hate it when...

Don't you just hate it when you have information to share but you are not permitted by contracts and commercial in confidence so share it? Our society is more and more being constrained by bureaucratic regulations set up by people who are career managers but have very little understanding of the real world. Little understanding that science and engineering knowledge benefit all people and that some perceived public image issue is more important than the wider good. This means that innovation can be stifled... at least in my personal opinion. The perceived public perception of scientific discoveries hinders the development of knowledge from Climate Change to Panadol!


By way of one a specific local example, I was helping an environmental centre have a ground water bore installed. The Department of Education which runs the environmental centre put absurd restrictions on access to the groundwater. One such limitation was that school children had to wear gloves when touching the groundwater in case it was contaminated. After running some tests it is apparent that the groundwater is actually better quality than the filtered tank water that they are currently drinking... but still the safety controls need to be in place! I'm happy to drink the water but the children must still wear gloves... go figure!


Another example is a cutting edge research project in the Woodburn-Evans area. The information gained from this research is very important for most coastal sand groundwater systems in eastern Australia. Alas, the words from a senior manager in a NSW government department are that no scientific information gained from the research is to be released to the public in the short term. What a shame. I understand that people are risk adverse today especially with regards to perceived public opinion but I don't think scientific knowledge should be hidden away.


On a slightly different note I have received a copy of an in-press paper on Coal Seam Gas monitoring in the Northern Rivers area. I provided some minor assistance in the paper and so an author kindly showed me before it was published. It is expected to be released in a few weeks and is likely to be in the newspapers too. Keep an eye out for those three letters C, S & G.
Sorry for the rant... just had to get that off my chest... hopefully a less opinionated post coming up shortly!

Unconventional Gas - Gaps in Baseline Data

The NSW Office of Water has been busy compiling a series of videos on YouTube explaining various aspects of hydrogeology. This recent video is about data gaps in understanding baseline hydrogeological conditions in areas of 'unconventional' gas.

This is what one aquifer looks like

In some amazing places you can immerse yourself in an aquifer. These places are rare and dominated by a rock type that does not occur in any substantial amounts in our region. However, people dive in the sub-terrainian waters of the limestone caves of the Nullabour in South Australia. The best aquifers in our region do not contain large caves compared with limestone areas. They are hosted in riverine alluvial sediments, fossil soil horizons in volcanic rocks, or fractures in hard metamorphic and volcanic environments. The main aquifers being on the coastal river flood plains, Alstonville Basalt and the New England areas respectively. However, volumetrically the sources that are very large are those in coastal sands.

Auger containing saturated sand from the Woodburn Sands

This post is an illustration of how one of those coastal sands aquifers looks. I've covered the Woodburn Sands in several previous posts but a quick summary is still needed. The Woodburn Sands are beach and dune sand that was laid down during the last significant interglacial. This was around 130 000 years ago during the Pleistocene period. The sea level was much higher than now and this meant that beach systems were often formed a significant way inland.

From the picture you can actually see what the medium that hosts an aquifer looks like. The Woodburn Sands are just that, sands. The sand grains are mostly quartz but there are also some grains made from volcanic and metamorphic rock fragments. Occasionally you can see grains of heavier minerals that were mined until the 1980's. The sand grains are very similar in size which is typical of wave and wind sorting. There is a very small fine fraction of clayey material.

Where the clay content is higher the ability of the water to flow through the aquifer is reduced. This is why some bores can only produce a small amount of water compared to the huge volume that is in the whole aquifer. This is an example of why aquifers tend not to behave as underground lakes. You can pump water out of one end and run out because the hydraulic conductivity (flow velocity) is not high enough to allow the water at the other end of the aquifer to flow in.

The Woodburn Sands is not the only important coastal sands aquifer in the region. Another very important water source include the Macleay sand coastal aquifers. These aquifers were formed in a similar way to the Woodburn Sands and are used for similar purposes. Usage includes irrigation, stock, domestic use and town water supply for places such as Kempsey and Evans Head. There are also some interesting arsenic contamination issues in one aquifer system (Stuarts Point) in the Macleay area which I will post on in the near future.

The similar characteristics of the coastal sands aquifer systems in the North Coast area has motivated the NSW state government to develop a Water Sharing Plan for these systems as a whole. The Water Sharing Plan is expected to be formally adopted this year (2014). Local governments regard groundwater from the coastal sands aquifers as very important. Rous Water has recently adopted its future water strategy which identifies coastal sands as the main source of additional information in the medium to long term and Mid-coast water have recently increased their production of groundwater for drinking too.

Available here is a presentation by the NSW Office of Water on the overall coastal sands systems in North East New South Wales

Where Does the Groundwater Flow?

There has been renewed interest in groundwater resources in the Northern Rivers of late. In part this is due to peoples concern about "unconventional" gas exploration and production in the area. Surprisingly, less known is the release of Rous Water's Future Water Strategy which includes groundwater as first on the list for new water sources. Rous Water is a major bulk drinking water supplier in the region. I've previously covered an area within the coastal sands groundwater source called the Woodburn Sands but this was a cursory look and I'd not covered where the groundwater actually goes.

Groundwaters do not exist as an underground lake in our region
Image courtesy of International Association of Hydrologists

Groundwater is often seen as a bit of an unknown, a black box, or some kind of underground lake (see the cartoon). It is quite difficult to observe and therefore people can get the wrong idea of what goes on underground.

One area that is not understood is that groundwater usually discharges somewhere. Sometimes groundwater discharge is obvious through springs. But where it intersects with permanent surface water it is much less obvious. The Evans Head area is a good example of where discharge from the Woodburn Sands aquifer and broader Coastal Sands aquifers is concealed.

Spring-fed creek on Chinaman's Beach.

While walking along Chinaman's Beach south of Evans Head during a recent long dry spell, I couldn't help notice the dark coloured water flowing over parts of the beach. This is one of those discharge areas I'm talking about (most people might be more used to seeing freshwater flowing over a beach from contaminated urban stormwater drains). The coastal sands above Chinaman's Beach holds groundwater and slowly discharges it at the beach. The dark colour of the water is from dissolved humic matter from coastal vegetation soaking into the sand. Tasting the water it was apparent there was no salt in it and understanding the groundwater area I knew it was clean. The springs I observed on Chinaman's Beach were obvious areas of groundwater discharge. The vegetation in the springs was lush and clearly reliant on the groundwater. This is formally known as as groundwater dependent ecosystems.

The lesser known discharge is not all through visible springs like those on Chinaman's Beach. Much of the discharge from the coastal sands aquifers is actually concealed by the sea. It might be a surprise to many in some areas just off the coast there are zones with freshwater. The amount of water that can be discharged underground into the sea can exceed the discharge from terrestrial springs (e.g. Santos et al. 2009). These are the undersea equivalent of the Chinaman's beach springs. This is interesting from a aquatic ecology point of view because it may mean that there are ecosystems in the ocean that are dependent on freshwater! That is, groundwater dependent ecosystems in the sea.

Groundwater is an interesting feature of our region. It is a source of drinking water, irrigation water and even industrial water. It is often important as some ecosystems are dependent on it. It is also surprising since ecosystems can be dependent on fresh groundwater even when out to sea.

Postscript: about a month after this blog post a story emerged in the local newspaper about sinkholes or zones of quicksand on Chinamans Beach. These quicksand 'pits' look just like typical groundwater discharge areas. The Northern Star article can be found here.


References/Bibliography:
*Santos, I.R, Burnett, W.C., Chanton, J., Dimova, N. & Patterson, R. (2009). Land or Ocean?: Assessing the driving forces of submarine  groundwater discharge at a coastal site in the Gulf of Mexico. Journal of Geophysical Research. vol114.

The Woodburn sands of time

I’ve been spending some time working on a project in the lower reaches of the Richmond River Valley. This project got thinking about the stratigraphy and depositional history of that area. Particularly about a unit of unconsolidated sand called the Woodburn Sands (Drury 1982). In some ways this post follows on from a couple of posts that touched on the subject of sea level changes during the Quaternary.

To begin to understand this unconsolidated sediments of the Richmond River Valley we turn to the most recent mapping of the area. Troedson et al. (2004) comprehensively mapped the coastal Quaternary sediments of the whole east coast of NSW. Troedson et al. (2004) demonstrated that over large areas of the lower Richmond Valley there are two units of coastal sand which formed in barrier environments. The most obvious coastal sands are active dune and beach systems formed from a barrier by the action of present day long-shore drift. These active barrier systems occur in many places along the coast. Troedson et al. (2004) also mapped extensive areas of what an earlier researcher Thom (1965) first identified as an inner coastal barrier. This inner barrier is comprised of an old beach system that is no longer active.

Drury (1982) undertook a comprehensive study of the Quaternary sediments of the Richmond River Valley. He confirmed the view by Thom (1965) that there was an old inner barrier system. This system was formed during a higher period of sea level than today and caused regional changes to coastal sedimentation (e.g. I previously posted on the estuarine sediments of the Lismore area). The high sea level eroded away the pre-existing beaches and formed new beach systems a significant distance inland (sometimes 15km or more). Then as the sea level retreated, the new beaches were no longer subject to erosion from the sea and were left intact. The beach systems continued to form on the sea-ward side of the old beaches and eventually built up a very large area of sand. These old beach systems are what made the Woodburn Sands.

The Woodburn Sands occur in a discontinuous zone from Broken Head National Park to the Evans River and the lowest reaches of the Richmond River (Swan Bay). The maximum thickness intersected is about 35 metres, so the sand layers can be very thick.

Like many places in eastern Australia, the action of coastal wave and wind processes can lead to concentrations of heavy mineral sand.  These deposits are called mineral placers. The Woodburn Sands is another of these areas where placers are common. Indeed, a lot of sand mining took place on the north coast to exploit the high concentrations of zircon, ilmenite and even gold. Presently, the Woodburn Sands is not mined for minerals but is used as an important source of good quality groundwater, this includes the regional town water supply authority.

Drury (1982) also included an unusual feature within the Woodburn Sands. This feature was named the Broadwater Sandrock by Mcgarity (1956). McGarity (1956) demonstrated that the Broadwater Sandrock was formed by the cementation of sand by organic rich material probably formed by changes occurring in a peat swamp environment. This sandrock is a common feature up and down the east coast of Australia. Another common feature is the diversity of names given to this material which include ‘indurated sand’, ‘coffee rock’, ‘coastal sandrock’, ‘painted rock’, ‘beach rock’, ‘humate’ and ‘B-horizon of the humus podzol’ (Drury (1982), Mcgarity (1956), Thom (1965) and Den Exter (1974)). Take your pick! I follow the terminology proposed by Drury (1982) who included the Broadwater Sandrock as a member of the Woodburn Sands, i.e. the Broadwater Sandrock member.

Postscript:
Since doing the above post an anonymous commenter has rightly corrected and provided further information. You can see the full comment below, the comment much more accurately describes 'coffee rock' formation but I reproduce this section specifically:

...humicrete (coffee rock) forms as the B-horizon of a fossil soil on sand (a podsol). It is NOT a sedimentary layer itself ie NOT a stratigraphic unit, so should not have been referred to as a "member" ...

As such, I have now changed my mind! The Broadwater Sandrock member is not the best name after all. It seems that 'B-horizon of the humus podzol' is indeed one of the best ones. Humicrete is another good one. Well, it seems that the diversity of names will probably continue, but we can remove the one I thought the simplest (Broadwater Sandrock member) from the list!

References/bibliography:

*Den Exter, P.M. 1974. The Coastal Morphology and & Late Quaternary Evolution of the Camden Haven District, NSW. Australia. PhD thesis. University of New England, Armidale.
*Drury, L.W. 1982. Hydrogeology and Quaternary Stratigraphy of the Richmond River Valley, NSW. PhD thesis. University of New South Wales, Kensington.
*McGarity, J.W. 1956. Coastal sandrock formation at Evans head, NSW. Proceedings of the Linnean Society of New South Wales. V81 p52-58.
*Thom, B.G. (1965). Late Quaternary morphology of the Port Stephens-Myall Lakes area, NSW. Journal of the Royal Society of New South Wales V98 p23-36.
*Troedson, A., Hashimoto, T.R., Jaworska, J., Malloch, K., Cain, L., 2004. New South Wales Coastal
Quaternary Geology. In NSW Coastal Quaternary Geology Data Package, Troedson, A., Hashimoto, T.R. (eds), New South Wales Department of Primary Industries, Mineral Resources, Geological Survey of New South Wales, Maitland.

The Koukandowie Formation has a cool Name

Previously I’ve completed blogs on the stratigraphy of the upper units of the Clarence-Moreton Basin. These upper units have been the Grafton Formation (youngest at Late Jurassic), Woodenbong Beds, Kangaroo Creek Sandstone and Walloon Coal Measures including the Maclean Sandstone Member of that unit (Middle Jurassic). Now, as we get towards the middle units of the basin we get into the Early Jurassic with much more complexity to the mode of formation of the geological units. Because of this the stratigraphic units have been divided into groups, subgroups, formations and members. The First one that I will tackle is the Koukandowie Formation, which is part of the Marburg Subgroup which in turn is part of the Bundamba Group.

The Koukandowie Formation actually is made up of an additional three members known as the Heifer Creek Sandstone Member, Ma Ma Creek Member and Towallum Basalt. But I’ll focus on these individually in future posts, for the time being it is worth noting that the Towallum Basalt is a very important unit for understanding the relative age relationships of all of the units in the Bundamba Group. For the time being I’ll focus on the Koukandowie Formation specifically.

Bundamba Group with conglomerate and abundant organic fragments - Tabulam

Unfortunately I do not have a photo specifically of the Koukandowie Formation. But I have attached a photograph a similar type of rock as the Koukandowie of the an undifferentiated part of the Bundamba Group.

The Koukandowie Formation was deposited in a dominantly fluvial (riverine) environment. Essentially the unit is comprised of sets of channel lithic sandstone (sandstone made from fragments of older rock) with some finer grained rock such as siltstone and even shale. But the formation also thin layers of conglomerate or occasional woody fragments that have turned into coal. The way the lithic sandstone was deposited means that a feature known as cross-bedding is very common and this structure is further evidence of its fluvial origin. The exact nature of these particular cross-bedding structures it interpreted by Wells & O'Brien 1994 as meaning that the river system that created the Koukandowie Formation was not a meandering stream but fairly straight. A modern example might be the middle reaches of the modern day Clarence River.

A rough stratigraphic guide to the Bundamba Group
(Walloon Coal Measures are above and Gatton Sandstone under)

The Koukandowie Formation was considered an important formation for gas and oil exploration in the region. The Koukandowie was thought to be a generally an impermeable unit, that is, stops the migration of fluids and gases such as oil and natural gas. This means that the underlying units of the Bundamba Group which are more conducive to forming and storing these gases and fluids may retain them in structural traps (such as folds in the earth or faults). How effective this unit has been seems to be a bit hit and miss. I understand that the NSW Government and some companies during the 1970’s and 1980’s had some success with this model but not enough to make it viable financially at the time. More recent work by exploration companies has shown this to be on its own not-viable. But when combined with similar modes of gas source rocks in the overlying Walloon Coal Measures, other more deeply buried organic rich units and other sources of gas directly from coal seams the economics seem to have looked good for some companies.

As for ground water sources, like the overlying Walloon Coal Measures the Koukandowie Formation does not contain much in the way of useful fresh groundwater. This is for two reasons:

1. the finer grained components of the formation tend to contain more salt due to the some of the sedimentary depositional environment; and
2. the Koukandowie Formation tends to show very little lateral porosity. This means that the water is stored in smaller localised aquifers of low long term yield. 

These reasons also imply the nature of recharge of what aquifers to occur in the area. Essentially vertical percolation from surface water through fractures is the main driver of aquifer recharge. Though there are exceptions due to the location of the sub-units in the Formation.

As for the name the Koukandowie Formation takes its name from Mount Koukandowie which is located near Nymboida. The formation outcrops in a relatively thin band in from the margins of the Clarence-Moreton Basin. I don't think that the formation outcrops anywhere in the middle areas the Clarence-Moreton Basin but certainly occurs at within the basin depth. The formation tends to weather and erode easily and therefore most of the outcrop of the unit shows relatively subdued landforms of rolling hills.

References/bibliography:

*McMahon, G.A. & Cox, M.E. 1996. The relationship between groundwater chemical type and Jurassic sedimentary formations: The example of the Sandy Creek Catchment, Lockyer, southeast Queensland. Mesozoic 96 Conference at Brisbane - extended abstracts.
*O’Brien, P.E. & Wells, A.T. 1994. Sedimentology of the Bundamba Group. In Wells, A.T. & O’Brien, P.E. 1994. Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Bulletin 241. Australian Geological Survey Organisation
*Wells, A.T. & O’Brien, P.E. 1994. Lithostratigraphic Framework of the Clarence-Moreton Basin. In Wells, A.T. & O’Brien, P.E. 1994. Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Bulletin 241. Australian Geological Survey Organisation.
*Wells, A.T., O’Brien, P.E. Willis, I.L. & Cranfield, L.C. 1990. A new lithostratigraphic framework of the Early Jurassic units in the Bundamba Group, Clarence-Moreton Basin, Queensland and New South Wales. B.M.R. Journal of Australian Geology and Geophysics. V11.

An excellent outcome from atmospheric atomic bomb testing

Human ingenuity surprises me again and again, especially the efficiency in which we can annihilate each other. During the 1940’s and 1950’s the superpowers were focused on increasing the efficiency in the way they could destroy everyone on the planet. It was a very worthy goal (yes that was a joke) and to achieve maximum efficiency they needed to conduct atmospheric tests of their bombs. Sometimes, unforeseen obvious benefits other than the benefits of death and destruction of humanity can arise.

I have recently been thinking about groundwater in the Richmond River area for which I have been consulting sections of a PhD thesis written by Leonard Drury in 1982 (Drury 1982). Drury's comprehensive thesis included qualitative identification on the age of groundwater in aquifers in the Richmond River by using an unstable isotope of hydrogen called tritium. Hydrogen is an atomic component of water (the H in H2O) but hydrogen actually comes in three natural forms based on the number of neutrons are in the nucleus of the hydrogen atom. These different forms are called isotopes. Hydrogen naturally has one neutron or less commonly two neutrons (called deuterium) and very rarely three neutrons (called tritium). In nuclear explosions the third isotope tritium, is created at concentrations much higher than the background. The reason why tritium is rare naturally is that it is only formed in the upper atmosphere but is unstable and loses the extra neutrons to become a smaller isotope over a period of time.

Half of the tritium in a given amount of water (or whatever) decays over a period of 12.5 years (this is called a half-life). Which means that over 25 years there is only a quarter of the original tritium left, 37.5 years one eighth, 50 years one sixteenth etc. Since tritium is not naturally occurring there is no practical use to measure for tritium unless you can introduce it into a system as a tracer and then measure its behaviour. This means that a large ‘slug’ of tritium was created during the 1940’s and 1950’s during atmospheric nuclear testing. Therefore if you can look for tritium in groundwater and if it is not present you can assume that that groundwater has been in existence for more than 50 years, i.e. it was present in the ground before any nuclear tests. If you detect tritium in several locations in an aquifer the relative abundance of the tritium will give an indication of the age of the water and whether mixing is occurring between old groundwater and new groundwater. It won’t give you an exact date but it will let you know a lot about behaviour of an aquifer.

The trouble is time is running out. The half-life of tritium means that as time goes on the ability for us to accurately measure the smaller amount of the isotope means that one day we won’t be able to use this as a technique. I was aware that time was running out on using tritium as an effective groundwater tracer but I was not aware how soon. I have had a few chats with an academic at Southern Cross University one of which was about using tritium, he said we actually only have about 5 or 10 years left to which I jokingly suggested to him that we should reset the tritium clock with some more atmospheric nuclear explosions! To which he informed me that actually there appears to be some more tracers that can be used following the Fukushima Nuclear Accident.

Bibliography/References:

*Drury, L.W. 1982. Hydrogeology and Quaternary Stratigraphy of the Richmond River Valley, New South Wales. University of New South Wales, PhD thesis.
*Moran, J.E. & Hudson, G.B. 2005. Using Groundwater Age and Other Isotopic Signatures to Delineate Groundwater Flow and Stratification. University of Illinois.
*U.S. Geological Survey (USGS), 2004, Stable Isotopes and Radiochemicals, in National Field Manual for the Collection of Water-Quality Data, Chapter A5 Processing of Water Samples. USGS Techniques of Water-Resources Investigation

Why you won't find CSG here now

As you might have noticed there has been an occasional blog post that I’ve done dealing with coal seam gas matters in a cursory manner. I’ve been asked again and again by many people to explain aspects of the industry and the environmental issues associated with it. I’ve worked in coal exploration and in an environmental capacity before and I know a moderate amount about gas extraction too but I’m afraid I don’t have all the answers. Caution is needed especially given the highly political nature of the subject now. Therefore, I don’t really want to weigh into the subject, but I’ll have a very quick comment or two just to really outline the big picture. In the last week I cautiously commented in the Northern Star online twice as the avatar ‘GeologyRod’ just to correct a couple of mistakes people have made. I’ve also written one letter to the editor cautioning about how to interpret water chemistry. Given the heated debate, I’m not sure I will do so again!

From what I understand of the coal seam gas industry and the geology directly applicable to the area I am not as concerned about the industry doing damage to groundwater sources or surface water as some. From my contaminated land experience, I do however; see two potentially serious environmental problems. These are failure of well casings causing local cross-connection of poor and good quality water (and gas) and the disposal of poor quality production water (salinity is the biggest problem, as the chemicals potentially used can easily be treated but salt is hard to get rid of).

Considering a risk assessment approach (using the possible outcome and likelihood of that outcome) provides many scenarios with only the two mentioned above displaying an elevated level of risk (in my very hastily developed opinion). The nature of the geology of the southern Clarence-Moreton Basin is such that regional scale ground water contamination touted as a problem by many is probably of negligible risk, though this may occur elsewhere in eastern Australia in places like the Surat and Gunnedah Basins. However, local groundwater contamination (with a chance of affecting someone’s water supply bore) is probably on the moderate to high side. The disposal of salty water poses a moderate risk to the environment through adversely affecting large areas of pasture which might be irrigated or a moderate to high level if discharged untreated directly to fresh water streams.

Both of the matters outlined above are difficult to deal with and not knowing about the ins and outs of operators in the region I don’t know how the companies are going to mange these problems. This is ignorance on my part. I can only assume that this has been considered in detail (a legal requirement) so that the management of these problems is adequate.

This is my opinion only and given that opinions can get one in trouble I won’t be commenting on any other matters CSG related for quite some time. I really don’t like getting involved in political matters and it is easy to be carried into them. I hope I haven't been carried into them too far already. If you want to know a bit more about the technical side of coal seam gas extraction and the pollution risks there are some good fact sheets put out by the CSIRO linked to here. Maybe that is why I like rocks so much, they don’t argue with you (too much).

But back onto happier topics. I’ve been most excited by some new information that has come my way, one a University of New South Wales thesis by Leonary Drury on the Richmond Valley stratigraphy, groundwater, dating and much more, and the other is the preliminary geophysical data package released by the NSW geological survey. I’ll be blogging on these topics (plus others) in the coming months.

Rocks named after a creek named after an Australian marsupial

Note that the stratigraphy of this formation has been revised since this blog post. See the this recent post for details.

One of the most widely outcropping rock units of the mesozoic aged Clarence Moreton Basin is the Kangaroo Creek Sandstone named after its type locality at Kangaroo Creek in the Nymboida area. It is also one of the most recognisable stratigraphic units in the basin.

McElroy (1963) showed that the Kangaroo Creek Sandstone consisted mainly of white to cream coloured quartz sand. The texture of the sandstone is saccharoidal, that is, it has a glistening sugar like appearance of the quartz sand grains. This sand glistens more than usual because while buried, fluids in the rock caused extra silica (quartz) to crystallise on the existing sand grains creating new tiny crystal faces that reflect light in a vivid way. The nature of the rock in this formation tends to weather less readily than other units and as a result tends to form prominent topographic features such as hills, cliffs, ridges and the like.

Crossbedding and typical saccharoidal texture in Kangaroo Creek Sandstone

The Kangaroo Creek Sandstone was deposited in a fluvial (river) setting and as a result cross bedding structures are very common in outcrops. Sorting of grains in the unit is very well developed, that is, the grain size is very similar at any particular outcrop. Additionally, the thickness of the beds is very consistent which together indicates that the tectonic setting was relatively unchanged through the period of deposition. Following burial of the sandstone fluids present in the rock caused extra dissolved silica to precipitate out onto the existing sand grains filling in voids and creating the characteristic texture.

The Kangaroo Creek Sandstone is considered by some authors (Wells and O'Brien 1998) to grade into the Woodenbong Beds in the north west of the NSW portion of the basin. However, it is noted that others (Willis 1998) consider the Woodenbong Beds the equivalent to the McLean Sandstone Member of the Walloon Coal Measures (but more about this in future post). The Kangaroo Creek Sandstone underlies the Grafton Formation but the contact with this formation is gradational. According to (Wells and O'Brien 1998) it also sometimes shows a conformable boundary with the underlying Walloon Coal Measures, however, in most areas the boundary is shown by an unconformity. It is easy to tell the difference however, because compositionally any sandstones in the Walloon Coal Measures are composed of feldspar and lithic grains rather than the quartz of the Kangaroo Creek Sandstone.

Outcrop of Kangaroo Creek Sandstone on the Clarence River near Grafton

It is interesting to note that the recrystalisation of quartz in the Kangaroo Creek Sandstone means that this unit is now essentially dry with respect to Ground Water. There is very few spaces left for the water to travel through. for example O'Brien et al (1998) shows that most other sandstones in other basins such as the Great Artesian Basin, is where most ground water is obtained. In fact, in the whole of the Clarence Moreton Basin the only unit to have useful ground water bores is the Grafton Formation which is recharged from rainfall. The Kangaroo Creek Sandstone does have some bores that produce a very little water in the upper most portion of the unit (probably rainwater recharging fractures in these locations (Kwantes 2011), like the overlying Grafton Formation) but it appears that no other bores obtain water from the Kangaroo Creek Sandstone because the formation actually behaves like an aquiclude or aquitard. Water is not obtained from aquifers below the Kangaroo Creek Sandstone because the water quality is generally poor.

It is interesting to note that according to some gas exploration results it is apparent that areas of the Kangaroo Creek Sandstone (assuming this is not mistakenly identified McLean Sandstone) that are directly overlying the Walloon Coal Measures contain substantial areas of conventional natural gas. This is gas that has migrated from the underlying Walloon Coal Measures and been trapped in either pore spaces or fracture zones. I understand that several companies in the area such as Metgasco and Red Sky Energy intend to exploit these reserves.

Pollen spores in drill holes give an age of middle to late Jurassic for the Kangaroo Creek Sandstone (Wells and O'Brien 1998).

References/Bibliography:

*Kwantes, E. 2011. Future Water Strategy: Groundwater Options - Position Paper. Report for Rous Water by Parsons Brinkerhoff.
*McElroy, C.T. 1963 The geology of the Clarence-Moreton Basin. New South Wales Geological Survey, Memoir 9, 172 pp.
*Moran, C., Vink, S. 2010 Assessment of impacts of the proposed coal seam gas operations on surface and groundwater systems in the Murray-Darling Basin. The University of Queensland.
*New South Wales Government. 2010. State of the Catchment Report: Groundwater. Northern Rivers Region. Department of Environment, Climate Change and Water.
*Wells, A.T. , O'Brien, P.E. 1994 Lithostratigraphic framework of the Clarence-Moreton Basin In Wells, A.T. and O'Brien, P.E. (eds.) Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Australian Geological Survey Organisation. Bulletin 241.
*Willis, I.L. 1994 Stratigraphic Implications of Regional Reconnaissance Observations in the Southern Clarence-Morton Basin, New South Wales In Wells, A.T. and O'Brien, P.E. (eds.) Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Australian Geological Survey Organisation. Bulletin 241.

Top of the Basin: The Grafton Formation

The Clarence Moreton Basin covers a large proportion of the catchment areas of the present day Clarence and Richmond Rivers in northern New South Wales and extends a significant distance more into south east Queensland. The portion of the basin which is most well known is the Queensland section but slowly we are learning more about the southern areas. The basin consists of many individual stratigraphic units which were deposited in slightly different environments at different times. The youngest unit is called the Grafton Formation and is thought to have been deposited during the Mesozoic era called the Cretaceous period which could be as young as 65Ma but it may be as old as late Jurassic.

The extent of the Grafton formation is small by Clarence Morton Basin standards because the majority of the unit appears to have been removed by erosion. Exposures can be found as far as 30km south of Grafton to about 10km north of Casino. The full remaining thickness of the formation has been estimated at up to 442m but is probably less with the best estimate of 267m obtained from a drill hole at Grafton.

Grafton Formation lithic sandstone near Casino

The formation is comprised of interbedded lithic to quartz arenites (sandstones), clayey siltstone, claystone and minor coal, sometimes 2metre thick conglomerate layers are present too. The lithic fragments frequently include the volcanic rock andesite implying active volcanism upstream at the same time as the sediments were being deposited. The bedding can be thin to thick and commonly a ferruginous (iron rich) lateritic weathering profile is present creating a very red coloured soil. This is particularly evident in the hills just to the north of Grafton such as Junction Hill. The sandstones are fairly characteristic in that they are usually tough and green-grey in colour.

One author (Wells and O'Brien 1994) suggests that the Grafton formation (and the Kangaroo Creek Sandstone) may also be equivalent to the Woodenbing beds (located between Urbenville/Woodenbong and Kyogle) and even though they are lithologically (rock composition) different this is still possible. An alternative by Willis 1994 is that it is the equivalent of the McLean Sandstone Member of the Walloon Coal Measures. But this will be discussed in detail in a future post.

The formation overlies the Kangaroo Creek Sandstone and is gradational meaning that the Kangaroo Creek Sandstone grades into the Grafton formation. Thankfully, recognising the difference is not hard on the basis of lithology (rock type) because the Kangaroo Creek Sandstone is very consistent in appearance (saccharoidal texture and abundant cross bedding) and consistent rock composition (quartz sandstone). The top Grafton formation has been eroded and is overlain by the more recent Cenozoic volcanics.

The Grafton formation was deposited in a mainly fluvial (riverine) environment with the more common siltstones and mudstones in the south probably being deposited in a lacustrine (lake) environment. This led to an idea that the source of the rivers and lakes that laid down the sediments in Grafton Formation was from the north but recent revisions of the probable mountain chains that existed at the time means that this many not necessarily be the case. Wells and O'Brien (1994) give the maximum age of the Grafton Formation as late Jurassic.

Interestingly, Grafton Formation is the only rock unit in the Clarence-Moreton Basin that has any significant or active ground water sources. The basin has proven to be a very poor source for water because of the lack of volume. In fact the only volume of water obtained from the Grafton Formation is really only unconfined aquifers recharged from surface water and overlying alluvium.


Note: Since writing this post it has been suggested in a new paper that the Grafton Formation appears to be made up of two members. The new paper by Doig & Stanmore (2012) significantly increases our knowledge of the Grafton Formation. I will endeavour to do a new blog post with the updated details.




References/bibliography:

*McElroy, C.T. 1969 The Clarence-Moreton Basin in New South Wales. In Packham G.H.(ed) The geology of New South Wales. Geological Society of Australia. Journal 16.
*New South Wales Government. 2010. State of the Catchment Report: Groundwater. Northern Rivers Region. Department of Environment, Climate Change and Water.
*Wells, A.T. , O'Brien, P.E. 1994 Lithostratigraphic framework of the Clarence-Moreton Basin In Wells, A.T. and O'Brien, P.E. (eds.) Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Australian Geological Survey Organisation. Bulletin 241.
*Willis, I.L. 1994 Stratigraphic Implications of Regional Reconnaissance Observations in the Southern Clarence-Morton Basin, New South Wales In Wells, A.T. and O'Brien, P.E. (eds.) Geology and Petroleum Potential of the Clarence-Moreton Basin, New South Wales and Queensland. Australian Geological Survey Organisation. Bulletin 241.