Research: Rehabilitation Methods for Potable Water Wells
1 December 2009
Research Into Optimizing Rehabilitation Methods for Potable Water Wells
Iron oxides in groundwater present significant maintenance and operational challenges when certain bacterial groups are present in sufficient numbers. The most problematic of these groups is commonly known as iron related bacteria (I.R.B.). These bacteria convert soluble iron into sticky clogging encrustations that reduce flows through the screen, pump and rising main. I.R.B. deposits have a profound negative impact on overall water production, geothermal heat exchangers and groundwater remediation facilities.
In the search for more sustainable, efficient well maintenance methods, Aquabiotics Industrial in Australia and Geoquip Water Solutions in the UK, in conjunction with key clients and strategic partners, have been researching methods to extend the maintenance intervals for wells with severe iron oxide clogging. Interim results from this research were presented in a paper at the WaterMed Conference 2009 in Rome.
One of the wells in the study had what is generally regarded as the worst iron oxide clogging in Western Australia. Historically after just 1008 hours of operation, the pump would be completely clogged and require a swap out to continue water extraction.
In February 2008 a combination rehabilitation treatment (BoreSaver Ultra C* and a bespoke cable tool rig) was undertaken giving the client a 200% improvement in the specific capacity.
In March 2009 the well was treated again in an identical manner to the 2008 treatment. With the 2009 rehabilitation, the starting point “untreated” was double that of 2008. This means the well performance had not deteriorated anything like as much as when standard rehabilitation techniques were used.
Previously the oxide thickness on the pump every 1008 hours of operation would be about 25mm thick with the intake port almost completely blocked. After the 2009 treatment an inspection at 4000 hours revealed just 3mm on the motor and no clogging at all of the intake port. Moreover, the expected decline in well performance, which had previously occurred every 1000 hours of pump operation, was not evident even after more than 4000 hours.
The Phased Treatment System has significantly increased the time between maintenance intervals, eliminated, to date, the clogging of the pump intake port and reduced rehabilitation costs.
Early conclusions of the research are that operators should make evidence based choices with beneficial management programmes for rehabilitation methods and techniques essential to reducing costs and efficient management of our groundwater resource. The research will be completed in 2011.
* Boresaver is a range of cleaning solutions for systems that are contaminated with iron oxide, manganese oxide and iron related bacteria. Boresaver Ultra C and Boresaver Liquid are approved by the Secretary of State under regulation 31 of the Water Supply (Water Quality) Regulations 1989 for use in potable water applications.