Repurposing of Abandoned Quarries in Sydney metropolitan for Water Supply StorageBy the aid of ArcGIS and Multi-Criteria Decision Analysis (MCDA).
The use of abandoned quarries as a new water supply storage in Victoria-Chung Han Chia copy.pdf Abstract Mining is an essential industry for the Australian economy. It also drives many other aspects such as community identity and population growth. However, across Australia the standard for mine closure has been subpar. This has lead to inadequate records of mining operations and often abandoned mines. These abandoned mines are a liability to the state as potential threats to health, safety, the environment and financially. There are examples of mines that that continue to threaten communities after being abandoned many years prior. This report aims to provide an investigation into a potential end use for abandoned quarries. The study focuses on abandoned quarries found in Victoria and is a proof of concept. Spatial analysis tools were utilized to develop a leader board of the most appropriate quarry for this end use. This proof of concept provides a perspective on how to evaluate a potential end use for current and abandoned mining operations. This is merely a rudimentary analysis of the potential considerations required to determine a suitable end use and should further expanded upon to determine a reliable evaluation. 1. INTRODUCTION The mining industry is crucial to the Australian economy. Since the gold rush in 1851 the mining industry has boomed. Mining has also caused an increase in the population that continues to grow as more minerals are extracted driving the Australian economy. However, many of these mines and quarries are being abandoned prematurely and have not received adequate rehabilitation measures. Many of these sites do not have clear ownership and is left to the government to deal with. It is estimated that there are 50,000 abandoned mines and quarries across Australia that require rehabilitation. (C. Unger et al., 2012). More recent studies performed estimates that there are in fact 75,000 mines are abandoned. (Matthew Roach et al., 2018) Many of these mines require rehabilitation as they are a serious threat to the environment as well as health and safety and are serious liabilities to states and territories. Mine rehabilitation is defined by the Mine Rehabilitation handbook (2016, pg. 3) as “…the design and construction of landforms as well as the establishment of sustainable ecosystems or alternative vegetation, depending upon post-operational land use.” The handbook also makes a distinction between site rehabilitation and site restoration. The handbook highlights that site rehabilitation attempts to restore the functionality and productivity of the ecosystem while site restoration aims to restore the ecosystem to a degree similar to before any mining disturbances has occurred. (Department of Industry, Science, Energy and Resources, 2016). There have been examples of successful mine rehabilitation. Calambeen Park and St George lake in Creswick was formed through collapsing mines to create recreational reserves that include large recreational lakes. These lakes support great biodiversity as well as provide recreational uses as an outdoor swimming area. Other examples include the use of Stawell goldmine in Stawell. This mine was converted into a research laboratory below the surface to research dark matter (SBS, 2016). In America, Atlanta is currently undergoing works to rehabilitate Bellwood Quarry into a water supply storage. Water will be transported from Chattahoochee river to the Hemphill water treatment plant before being transported to Bellwood quarry for storage (City of Atlanta Department of watershed management, 2019). As such this study explores the possibility of transporting treated water to sites for water storage. An increase in population has resulted in an increase in water demands. It has been evident from the decade long drought experienced from early 2000’s to 2010 that Australia’s water supply was being taken for granted. As such better water management methods needs to be implemented to ensure Australia’s water security. As a solution to the increasing water demands of the future and the negative impacts that abandoned quarries have economically, environmentally and socially; it is suggested that abandoned quarries be rehabilitated into a water supply storage. This research intends to provide a proof of concept. It intends to determine the feasibility of specific sites for rehabilitation. This form of site rehabilitation will address demands for increase in water demand as well as the need to rehabilitate mines that are causing socio-economic and environmental damages. The use of abandoned quarries as a new water supply storage in Victoria Chung Han Chia*, Mohan Yelishetty, Peter M. Bach and Stuart Walsh Environmental and Resources Engineering, Department of Civil Engineering, Monash University, Melbourne, Victoria, Australia. 2. METHODOLOGY Table 1: Criteria and Objectives for MCDA to determine abandoned mine sites appropriateness for rehabilitation option The analysis requires the use of spatial analysis tools. Information about abandoned and current mining operations are obtained from research performed by Alec Miller & Mohan Yellishetty, 2017. Most viable abandoned quarries is presented in this study. These sites were analysed with the spatial analysis tool QGIS using Multi Criteria Decision Analysis (MCDA) to assess their appropriateness, 2.1 Multi-Criteria Decision Analysis (MCDA) The proposed method of MCDA was Weighted Sum Method (WSM). This method requires a score to be given to various objectives. These scores were be on a 5-point scale and a weighting factor was applied to each objective. A final score was tallied and the higher the score the more desirable the site is. Objectives have been developed from 3 main criteria. - Socio-economic impacts - Biophysical impacts - Governance and planning The objectives have been outlined for each criterion and can be seen in Table 1. As a preliminary study it is noted that further objectives may be included to the analysis to further the evaluation of the abandoned quarries. Limitations in available information and processing power has led to the application of WSM to certain objectives only. The most appealing sites was further evaluated against other objectives individually. These objectives are: Criteria Category Objectives Biophysical Climate Receive suitable amount of rainfall/runoff to maintain minimum supply volumes Geography Site of suitable capacity to store water supply Site situated on the high ground to aid with pumping infrastructure Biodiversity Achieve a level of restoration to the ecosystem Environmental Ensure water quality is not endangered by pollutants Socio economic Population Located within an area which is expected to grow significantly in population Meet local water demands Cost Proximity to current water infrastructure Projected construction Planning & governance Development opportunity Located within an area which has plans to grow Heritage Heritage/zoning status of the quarry - Achieving a level of restoration to the ecosystem - Ensuring water quality is not endangered by pollutants - Sites that exist in the vicinity of a growing population - Located in a region with plans of development - The site is relatively close to current distribution network and water infrastructure After performing the MCDA with QGIS the top- ranking quarry was further analysed. 2.2 Weighted Sum Method (WSM) The weighted sum method was used to determine the appropriateness of site locations due to its simplicity in application. Direct weighting was applied and was determined by various literature. There are many limitations to direct weighting methods. The main concern is the chance of bias (Németh B. et al. 2015). Due to resource limitations, the simplicity of this weighting method is most appealing for this study. To understand the potential for biasness, a sensitivity analysis was performed on the weighting. The resulting score was analysed to view the objectives effects on the score. 2.3 Biophysical The biophysical criteria mainly incorporate natural phenomena and features that can be assessed. Biophysical components include climate, geography, biodiversity and environmental aspects. It is desired that mines receive enough natural rainfall to support its own supply levels. Contributing catchment areas were determined to understand the potential water levels in the water supply storage. However, if allowed, treated water from water treatment plants will be used to sustain water levels. An example of this is Bellwood quarry in Atlanta, Georgia. It is currently being developed as of 2020 and transports treated water from Hemphill water treatment plant. Hemphill is located 5 miles (8 kilometres) from Bellwood quarry (City of Atlanta Department of watershed management, 2019). Sites were analysed for their distance from potential water suppliers post MCDA analysis on QGIS. Sites will be desired to have an elevation higher than populated regions to reduce strain on water pumping infrastructure. This analysis was also done post MCDA analysis on QGIS. Rehabilitation of sites aim to restore damaged ecosystems. This is a key goal of mine rehabilitation. The Mine Rehabilitation Handbook states that one of the key design objectives should be to partially or fully repair the ecosystem to provide habitats and service to people (2016). This objective was determined by the use the Strategic Biodiversity score by Natureprint (Department of Environment, Land, Water and Planning, 2019). This is a map overlay that provides a measure of the biodiversity seen in Figure 1. Figure 1 Strategic Biodiversity Score (Natureprint, 2016) For rehabilitation, a low biodiversity is desired at site locations. In south-east Australia, endangered bat species reside in some of the abandoned mine shafts (Greenpeace, 2017). Hence a low biodiversity score will be less likely to avoid damaging pre-existing fragile ecosystems. Lastly, the site location must be protected from potential pollutants in the area. Potential sites were judged in the MCDA on QGIS against an overlay of Historic polluted groundwater sites (EPA Victoria, 2019). These polluted sites occurred from various activities that resulted in areas that are still damaging the groundwater. Further analysis is required to understand the extent of the effects to site locations. This is represented in Figure 2. Figure 2 Polluted Groundwater sites (EPA Victoria, 2016) 2.4 Socio-economic The objectives of the socio-economic criteria is to locate a site in a region that is expected to have an increase in population, meet future water demands, lower construction cost, maintenance cost and the use of existing water infrastructure. Site locations are desired to be within an area