Discrete interval groundwater samples from uncased boreholes in the Hawkesbury Sandstone, NSW, Australia, reveal mixed results.

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dc.contributor.authorPeterson, MAen_AU
dc.contributor.authorCendón, DIen_AU
dc.contributor.authorHankin, SIen_AU
dc.contributor.authorChisari, Ren_AU
dc.date.accessioned2022-07-22T02:04:14Zen_AU
dc.date.available2022-07-22T02:04:14Zen_AU
dc.date.issued2013-09-19en_AU
dc.date.statistics2022-01-24en_AU
dc.description.abstractThe effects of subsidence and related fracturing from longwall coal mining have raised community concern around the Southern Coalfields of NSW. Shallow fracturing of bedrock streambeds has led to draining of perennial pools and localised diversion within some streams. Consequently, the risk of diverting surface water and shallow groundwaters towards underground mining operations has also been debated in the community. A Zone-of-Interest Groundwater Sampler (ZoIGS) with straddle packers and multiple pressure sensors was used to collect samples from discrete 5 m intervals within uncased 100 mm boreholes. Up to 6 intervals were successfully sampled in each borehole, to a maximum depth of 137 m below ground level. Hydrogeochemical information analysed comprised major ions, water stable isotopes, 3H and 14CDIC . The results were compared to geophysical data and pressure recovery after purges for each of the intervals. Each borehole displayed a unique vertical arrangement of apparent ages, hydraulic conductivities, mixing and pressure gradients. Hydrogeochemical results showed that some of the more evolved groundwater at depth, with corrected 14C ages up to a few thousand years, was also displaying a 3H signature of mixing with much younger waters. In some cases age profiles were overturned with depth, with younger water occurring below older water. Geophysical and pressure recovery data showed that each borehole intersected a number of aquifers, separated by shale aquitards up to five metres thick. The shale beds are sometimes closely associated with high horizontal hydraulic conductivities and outflow zones. 3H indicative of younger water did not always coincide with the higher hydraulic conductivity zones. The results describe a complex heterogeneous system within the Hawkesbury Sandstone, with multiple flow paths contributing to mixing of old and young groundwater at depth. The ability to sample and investigate numerous discrete intervals within uncased boreholes gave an opportunity for better understanding the system, with minimal infrastructure.en_AU
dc.identifier.citationPeterson, M. A., Cendón, D., Hankin, S., & Chisari, R. (2013) Discrete interval groundwater samples from uncased boreholes in the Hawkesbury Sandstone, NSW, Australia, reveal mixed results. Paper presented to the IAH 2013, Perth, Australia : "Solving the groundwater challenges of the 21st century", International Association of Hydrogeologists 40th International Conference, Perth, Western Australia, 15-20 September 2013, (pp. 166).en_AU
dc.identifier.conferenceenddate20 September 2013en_AU
dc.identifier.conferencenameIAH 2013 Perth Australia : 'Solving the groundwater challenges of the 21st century', International Association of Hydrogeologists 40th International Conferenceen_AU
dc.identifier.conferenceplacePerth, Western Australiaen_AU
dc.identifier.conferencestartdate15 September 2013en_AU
dc.identifier.otherSession Four B, 578en_AU
dc.identifier.pagination166en_AU
dc.identifier.urihttps://apo.ansto.gov.au/dspace/handle/10238/13418en_AU
dc.language.isoenen_AU
dc.publisherInternational Association of Hydrogeologistsen_AU
dc.subjectGround wateren_AU
dc.subjectNew South Walesen_AU
dc.subjectAustraliaen_AU
dc.subjectSandstonesen_AU
dc.subjectLongwall miningen_AU
dc.subjectCoal miningen_AU
dc.subjectCarbon 14en_AU
dc.subjectSurface watersen_AU
dc.subjectStable isotopesen_AU
dc.titleDiscrete interval groundwater samples from uncased boreholes in the Hawkesbury Sandstone, NSW, Australia, reveal mixed results.en_AU
dc.typeConference Abstracten_AU
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