Little Forest Burial Ground - geology, geophysics and well installation 2009-2010

This document reports on a program of drilling at Little Forest Burial Ground undertaken in the period 2009-2010 under the supervision of the ANSTO's Nuclear Methods in Earth Systems (NMES) project. Under this program, the following activities were undertaken: resistivity, ground penetrating radar and electromagnetic geophysical surveys to define the trench area and investigate stratigraphy; core and crushed soil/rock sampling by drilling (direct-push, solid flight auger and diamond core) at 0.5 metre intervals at 40 locations; installation and development of 18 groundwater observation wells; survey of new wells and trench boundary marks in MGA94 coordinates and AHD (Australian Height Datum). This report presents: a summary of existing knowledge of the burial ground and neighbouring sites, including a detailed discussion of the geological setting (Chapter 1); the objectives for the work undertaken (Chapter 2); a detailed description of all methods used (Chapter 3); a discussion of geophysical, drilling and well construction results and observations of the campaign (Chapter 4); recommendations for further work (Chapter 5). The appendices provide an extensive summary of the construction details of all operational wells at the site, including geological logs, survey coordinates and elevations. A brief evolution of the site as documented by aerial photography is included at Appendix C. Interpretation of chemical/radiological data from the soil and water samples retrieved as a result of the drilling activities will be presented in separate reports

Groundwater residence time in the Kulnura-Mangrove Mountain Plateau (Gosford, NSW, Australia)

The Kulnura-Mangrove Mountain plateau consists of the catchments of Mangrove, Narara, Mooney Mooney, and Ourimbah Creeks, and Wyong River. Groundwater plays a key role in sustaining stream flow within these catchments. Estimates indicate up to 50% of annual stream flow is derived from baseflow. The local community water supply relies on the groundwater within the elevated Hawkesbury- Narrabeen sandstone plateau. Furthermore, the Gosford-Wyong Councils’ Water Authority (WSA) is the third largest in NSW and utilises many of the streams flowing from the sandstone plateau for municipal water supply. It is anticipated that the WSA will provide municipal water for 319 000 persons by the year 2010. The increasing volumes of groundwater being extracted and changing land use have the potential to cause damage to the fresh water aquifer through contamination and aquifer depletion. A hydrogeochemical survey (2006-2009) has been conducted in NSW Dept of Water and Energy (DWE) monitoring wells across the plateau in order to determine groundwater residence times. Groundwater was analysed for major ions, minor and trace elements, H2O 18O and 2H, 13CDIC, 87Sr/86Sr, 14CDIC, and 3H, and complemented with mineralogical and isotopic information obtained from soil and drill chips collected during well construction. Water stable isotopes confirm the meteoric origin of the groundwater with most values plotting on the local meteoric water line. Localised evaporative trends suggest recharge with evaporated groundwater stored in ponds. Shallow groundwaters have 3H and 14C activities consistent with modern recharge (Fig 1). Carbon “bomb pulse” signatures of up to 116.8 pmC are found in the central areas of the plateau. The thin soils, lack of carbonates in the intensely weathered near-surface Hawkesbury sandstone, and the shallow depth of the water samples is consistent with the 3H results measured, suggesting minimal dilution of the original 14C. Input of this data into a southern hemisphere bomb pulse model [1] suggest potential recharge during the 1990´s, coinciding with sustained wet conditions and above average rainfalls experienced during this period. Fig. 1. 14C vs 3H plot of groundwater samples in the Kulnura- Mangrove Mountain Plateau Deeper groundwaters have lower 14C and 3H activities in some cases close to background level (Fig. 1). The quantifiable 3H suggests residence times of <70 a. However, non-corrected 14C residence times are submodern (>500 a). This apparent discrepancy can be explained by either mixing with older waters or dissolution of carbonates. The good correlation of total dissolved inorganic carbon (TDIC) and Ca (R2=0.8), 13CTDIC in groundwater and mineralogy results from drill chips suggest that dissolution of dispersed carbonates is taking place. The deepest groundwaters show the most difference in residence time across the study area. The eastern and western plateaus yield old groundwater with 14C corrected residence times of around 9 ka and 4 ka respectively. However, the groundwater at equivalent depths in the central plateau was found to be considerably younger with residence times of <70 a

Theory of mirror benchmarking and demonstration on a quantum computer

A new class of protocols called mirror benchmarking was recently proposed to measure the system-level performance of quantum computers. These protocols involve circuits with random sequences of gates followed by mirroring, that is, inverting each gate in the sequence. We give a simple proof that mirror benchmarking leads to an exponential decay of the survival probability with sequence length, under the uniform noise assumption, provided the twirling group forms a 2-design. The decay rate is determined by a quantity that is a quadratic function of the error channel, and for certain types of errors is equal to the unitarity. This result yields a new method for estimating the coherence of noise. We present data from mirror benchmarking experiments run on the Honeywell System Model H1. This data constitutes a set of performance curves, indicating the success probability for random circuits as a function of qubit number and circuit depth

Installation of a pilot experimental trench at the Little Forest legacy site

During 2017, a pilot experimental trench was constructed at the Little Forest Legacy Site (LFLS). The objective of installing this trench was to facilitate experimental field-work aimed at further characterising the site, in particular the hydrology of the excavated trenches and of the near-surface layers in which the trenches are located. The test trench is of similar depth to the waste disposal trenches at the legacy site (3 metres) and extends 6 m in length. However, unlike the disposal trenches, the experimental trench contains no waste materials of any kind. Instead, the trench contains a number of sampling points and other instrumentation, and is back filled with river gravel to provide a uniform composition and maintain structural stability. It is intended that the pilot trench will be followed by other trenches with specific experimental objectives. The purposes of this report are to discuss the background, rationale for, and implementation of the facility; to provide a detailed description of the pilot trench; and to compile information and photographs documenting the excavation process. Although some preliminary hydrological data and comparisons with the legacy trenches are presented, the scientific data will be fully discussed and interpreted in future scientific reports

Smoking and Risk of Kidney Failure in the Singapore Chinese Health Study

Background:The relationship between smoking and risk of kidney failure, especially in people of Chinese origin, is not clear. We analyzed data from the Singapore Chinese Health Study to investigate whether smoking increases the risk of kidney failure.Methods:The Singapore Chinese Health Study is a population-based cohort of 63,257 Chinese adults enrolled between 1993 and 1998. Information on smoking status was collected at baseline. Incidence of kidney failure was identified via record linkage with the nationwide Singapore Renal Registry until 2008. Kidney failure was defined by one of the following: 1) serum creatinine level of more than or equal to 500 μmol/l (5.7 mg/dl), 2) estimated glomerular filtration rate of less than 15 ml/min/1.73 m2, 3) undergoing hemodialysis or peritoneal dialysis, 4) undergone kidney transplantation. Cox proportional hazard regression analysis was performed for the outcome of kidney failure after adjusting for age, education, dialect, herbal medications, body mass index, sex, physician-diagnosed hypertension and diabetes mellitus.Results:The mean age of subjects was 55.6 years at baseline, and 44% were men. Overall 30.6% were ever smokers (current or former) at baseline. A total of 674 incident cases of kidney failure occurred during a median follow-up of 13.3 years. Among men, smokers had a significant increase in the adjusted risk of kidney failure [hazard ratio (HR): 1.29; 95% CI: 1.02-1.64] compared to never smokers. There was a strong dose-dependent association between number of years of smoking and kidney failure, (p for trend = 0.011). The risk decreased with prolonged cessation (quitting ≥10 years since baseline). The number of women smokers was too few for conclusive relationship.Limitation:Information on baseline kidney function was not available.Conclusions:Cigarette smoking is associated with increased risk of kidney failure among Chinese men. The risk appears to be dose- and duration-dependent and modifiable after long duration of cessation. © 2013 Jin et al

Groundwater response to heavy precipitation.

An investigation of the groundwater response to heavy rainfall at Lucas Heights Science and Technology Centre (LHSTC) is required under the conditions of Facility Licence F0001 for the ANSTO's Replacement Research Reactor. Groundwater continuous hydrograph monitoring has been used for this purpose. Hydrograph data from four boreholes are presented showing the rainfall recorded during the same period for comparison. The drought conditions have provided only limited cases where groundwater responded to a rainfall event. The characteristic response was local caused by saturated soil contributing water directly to the borehole and the falling head as the water was redistributed into the aquifer in a few hours. Hydrograph data from borehole near the head of a gully showed that groundwater flow from the plateau to the gully produced a peak a few days after the rainfall event and that the water level returned to its original level after about 10 days. The hydrograph data are consistent with an imperfect multi-layer groundwater flow regime developed from earlier seismic and geophysical data with decreasing rate of flow in each layer due to decreasing hydraulic conductivity with depth. The contrast in hydraulic conductivity between the thin permeable soil layer and the low permeable sandstone forms an effective barrier to vertical flow

Groundwater modernisation and associated chemical changes in a Hawkesbury sandstone acquifer (Kulnura–Mangrove Mountain, NSW, Australia)

Land and groundwater usage has the potential to influence the groundwater chemistry of an aquifer. Progressive modernisation of groundwater, variation in pH and associated water/rock reactions have been identified in areas of the Kulnura–Mangrove Mountain aquifer (KMMA). Detailed temporal and spatial sampling of groundwater (general hydrogeochemistry, H2O stable isotopes,  13CDIC, 3H, 14C and 87Sr/86Sr) revealed important inter-annual variations driven by groundwater extraction showing a progressive influx of modern groundwater at >100 m depth in some areas. In the Peats Ridge plateau, shallow groundwater samples show high 14C bomb pulse signatures, indicating modern recharged groundwater, while deeper groundwater shows a yearly increase in modern 14C inputs, instead of lower a14C values, as observed in other wells and generally expected. Values evolved from 36.1 pMC (5.2 ka BP) in 2007, to modern values of 103 pMC in 2010 with the latest sample in 2012 failing to graphitise, probably due to the high CO2 generally linked in the study area with modern groundwater. The 3H activities have also evolved from values below the quantification limit in 2007 and 2008 to values of ~1.1 TU in 2012. The minimal buffering capacity of the quartzose sandstone aquifer, at least in its upper zone where dispersed carbonates have long been dissolved, means that shallow groundwater generally has a low pH. Limited historical data (1998) shows higher pH for all samples compared to the same wells analysed for this work. However, it is in the central area where pH changes are most evident. During 2007, groundwater pH was similar to that expected for samples at similar depths with consistent groundwater residence times; however, successive samples show a shift to lower pH similar to those found in much shallower samples, as well as modern groundwater ages. Groundwater extraction is therefore causing an inflow of modern waters at depth with associated acidification. An important consequence of acidification is the capacity to mobilise trace metals. Of particular interest is aluminium as it has been linked to enhanced risks of cognitive decline for subjects with a high daily intake from drinking water (≥ 3.7 µM·day−1 ). Shallow samples in the Mangrove Mountain area and some of the deeper samples with Al concentrations of ~3.45 µM are a risk for average drinking water intakes. The movement of low pH shallow groundwater is causing an increase in Al concentrations, particularly in the central area of the KMMA, and this may be affecting groundwater for local consumption or that recovered in bottling plants. © Geological Society of Australia In

Deep meteoric leaching and its implications for groundwater residence time in a dissected Hawkesbury sandstone plateau (Kulnura-Mangrove Mountain Aquifier, NSW, Australia).

In the Kulnura-Mangrove region, groundwater extraction for potable water supply and for industrial activities such as farming and mining, can co-exist provided the main recharge areas are protected, pumping does not exceed recharge, and knowledge of the basic parameters within the aquifer are known through appropriate studies. In this study, groundwater residence time in the Kulnura-Mangrove Mountain aquifers was assessed over multiple years using environmental tracers (H2O stable isotopes, 13CDIC, 3H, 14C and 87Sr/86Sr) and general hydrogeochemistry. The Kulnura-Mangrove Mountain aquifer is mostly hosted in its upper part by the Hawkesbury Sandstone, where intense and deep sandstone weathering profiles have resulted in enhanced groundwater storage. Weathering reactions favoured by the local geological setting has transformed the original Hawkesbury Sandstone quartz arenite into a semisolid or friable sandstone with variable weathering depths where most of the original carbonate cements have been leached, resulting in higher porosity and permeability. XRD analyses show an upper zone down to ~50 m and even 90 m in some areas where all carbonates and probably feldspars have been dissolved and the derived products goethite and kaolinite have formed. With depth, carbonates, mostly siderite, are present representing fresher or less-weathered sandstone. Isotopic analysis of dispersed carbonates shows consistent values with their depositional environment and devoid of 14C. The study incorporated whole rock analysis from samples recovered during well construction at four sites to better characterise water–rock interactions. Based on hydrogeochemistry, isotopic tracers and mineral phase distribution from whole rock XRD analysis, two main groundwater zones are differentiated in areas not disturbed by groundwater extraction. A shallow zone where oxidising Na–Cl-type waters with low pH and EC contain 3H and 14C activities consistent with very modern groundwater affected by bomb pulse signatures (up to 116.9 pMC). In this shallow zone the original Hawkesbury Sandstone has been deeply weathered, enhancing storage capacity for groundwater down to ~50 m in most areas and up to ~90 m in the Peats Ridge zone. The deeper groundwater zone is also relatively oxidising with a tendency towards Ca–HCO3 type waters, higher pH and EC, no 3H and 14C activities consistent with residence times from 0.9 to 11.8 ka BP, depending on the specific areas. The original sandstone is less weathered with depth, favouring the dissolution of dispersed carbonates and a transition to a fractured-rock flow type aquifer, both impacting on groundwater mean residence times

Recharge rates and connectivity of grouwater in deeper aquifers of the Sydney Basin

The Permo-Triassic Sydney Basin covers almost 50 000 km2 and extends from the outer continental shelf inland to the Great Diving Range, from Newcastle in the north to Batemans Bay in the south. Major lithological units broadly include the Permian Coal Measures, the Permo-Triassic Narrabeen Group, the Triassic Hawkesbury Sandstone and the Wianamatta Shale. The Hawkesbury Sandstone is generally made of very thick heavily compacted quartz sands, with minor discontinuous shale units. Its aquifer system is a complex, dual porosity, deep fractured system with three aquifers typically recognised. The shallow and intermediate aquifers contribute to spring and base stream flows as well as groundwater dependent ecosystems, and the deep regional aquifer system. It is this deeper system that is investigated in this study. Groundwater from the Sydney Basin, and in particular Hawkesbury Sandstone aquifers, forms part of emergency supply strategies for coping with future severe droughts, with >5 million people living in the region, in addition to large industrial development. Despite the significance of these resources there are still large gaps in our knowledge of these aquifers including aspects such as age recharge and mixing rates. Filling these knowledge gaps has become even more critical in order to understand impacts of existing and planned coal and coal seam gas (CSG) mining of the underlying Illawarra Coal Measures. Community concerns over risks associated with CSG extraction have reached fever pitch in recent years, and there is public demand for research into these aquifers. Understanding of these systems has been complicated by the poor quality of existing data – commonly relying solely on driller bore-logs, reporting only being carried out for specific mine or extraction activities, and therefore conducted over localised zones, and the lack of communication between companies and agencies with data. Additionally, large variations in hydraulic properties have been noted over localised areas. This study sampled bores along a loosely east–west transect across urban Sydney, targeting the deeper Hawkesbury Sandstone and Narrabeen group aquifers. Very high salinities are recorded by several samples, interpreted to relate to the influence of the overlying Wianamatta Group and Cumberland Basin sediments in those locations. Equally however, this signal may record the impact of interaction with coal seams. Results also show inconsistencies between tritium and radiocarbon groundwater ‘ages’ in multiple locations, suggesting that extensive mixing occurs between aquifers. A relationship between bicarbonate, depth and δ13C isotopic ratios highlights the influence of methanogenesis for deeper samples and either interaction with localised organic matter or deeper inputs derived from the coal measures. These findings have implications for potential coals seam gas extraction in the region, demonstrating that impacts could be significant in areas of high fracturing and connectivity. This supports previous assessments of groundwater vulnerability and the need for further detailed research

Irrigation bore water in the Condamine Catchment: baselining groundwater quality and assessing pathways of hydraulic connectivity

The expansion of coal seam gas production adjacent to the irrigation farming districts in the Condamine Catchment has raised concerns about the impact of gas production on groundwater in adjoining aquifer systems. To assess the risk, and to be able to detect any future changes in groundwater properties, existing groundwater chemistry data sets need to be updated and expanded. Historically, the testing of groundwater chemistry in the Condamine Catchment has focused on the Queensland Government groundwater-monitoring network, but it is unlikely that these samples come from the same sand and gravel bodies from which the irrigation bores extract groundwater. We report the result of 20 groundwater samples collected from bores that supply irrigation water for cotton and other crops. These samples were collected in January 2014 at the end of the pumping season, when the aquifer system is at peak stress for the year. We compare the major ion chemistry recorded in the irrigation bores to that measured at selected sites from the QLD government groundwater-monitoring network and with historical results reported in the literature. A hydrochemical facies analysis of these data provides one assessment of the likelihood of hydraulic connectivity between the Walloon Coal Measures, other bordering Great Artesian Basin formations and the valley filling sediments of the Condamine Alluvium. The results highlight variation in groundwater chemistry within the Condamine Alluvium, particularly in the Cecil Plains and Dalby regions, where there are signs of water mixing. As a result, further research into the area to explain the baseline data sets would provide a better understanding of hydraulic connectivity and the potential effects of CSG on the groundwater