By Jackson Newton and Claire Stephenson
Sustainable Well: Maintenance, Problem Prevention, and Rehabilitation
Authors: Stuart A. Smith, Allen E. Comeskey
Publisher: CRC Press Taylor & Francis Group
AGE recently came across a great resource on how to maintain and treat bores to ensure they keep performing to their full capacity. Authors Smith and Comeskey bring a combined 80 years of expertise in bore deterioration monitoring, management and remediation into one handy, compact book. The book outlines the causes and effects of bore deterioration. This includes a great (hitchhiker’s) guide to biofouling, which they describe as “the number one contributor to reduced well performance… across the globe”
The first indicator of biofouling is normally increased concentrations of iron, manganese and sulphur within the groundwater. Further indicators of hydrochemical change include increased turbidity, odour and corrosion of pump components. Biofouling involves the oxidation of chemical compounds (i.e. iron, manganese and sulphur), which largely occurs within the redox fringe. The redox fringe is the interface between zones depleted of oxygen and those with free oxygen, which is important for the development of biofouling organisms.
Bore performance depends on a variety of environmental, hydraulic, and use factors. Biofouling can reduce this performance clogging pumps, pipes and screens, and reducing hydraulic conductivity. The effects of hydraulic conductivity reduction due to biofouling are largely controlled by the transmissivity of the aquifer. Highly transmissive gravels for example, are much less likely to display noticeable plugging effects from biofouling compared to a poorly transmissive, fine grained aquifers.
Biofouling may also encrust or loosely plug bore screens, pumps, and other equipment over a period of weeks, months, or years, depending on the environment. The book draws attention to the importance of regular assessments into the condition of groundwater bores. Without regular monitoring of water quality and aquifer performance, it is possible that the effects of biofouling may not be detected until they are in advanced stages. This can pose health risks to users, degradation of infrastructure, and increased remediation and maintenance costs.
The effects of biofouling extend beyond operational issues, with several potential detrimental health effects resulting from the presence of microorganisms. This can include bioaccumulation of arsenic, heavy metals, and radionuclide contamination. The book provides in-depth details on options to treat and prevent biofouling. Treatment options include a range of non-oxidising chemicals (i.e. acids) and mechanical aids for surging and agitating the bore to physically dislodge materials.
AGE have found the book to be very useful for the treatment of bores affected by biofouling in regional Queensland. Water supply and monitoring bores require a significant capital investment for many, so managing and maintaining the performance of bores is vital. This is a great book for anyone who owns or manages monitoring and water supply bores.
AGE has significant experience in bore testing and assessment. We can assist you with any queries you may have regarding bore performance and fouling. Enquiries can be directed to [email protected].
Another useful resource for landholders is the government’s recently established National Groundwater Information System (NGIS) database (www.bom.gov.au/water/groundwater/ngis). The interactive site provides easy access to information about groundwater bores across Australia. You can zoom to your location and find out details such as the use, geology and depth of bores and wells registered in your area.