Abstract:
Aquifer Storage and Recovery (ASR) involves the injection of water into an aquifer for
subsequent recovery from the same well. Whilst ASR provides a competitive alternative
to reservoir storage, a lack of precedence of successful schemes and uncertainties with
respect to regulatory requirements, and abstracted water quality and quantity have
limited its implementation in the UK. The ambition of this research is to improve
understanding of these impediments with particular reference to the Sherwood
Sandstone aquifer. Drawing on existing project review and risk management
approaches, a decision support tool to help scheme designers scope ASR scheme
potential and challenges was developed and tested. The tool provides practitioners with
a systematic method for early stage evaluation of ASR schemes with testing confirming
broad value and alignment with business processes. Limitations on the recovery of
recharged water was investigated through a critical literature review on clogging with
geochemical, biological, physical and gaseous binding processes identified as the most
likely mechanisms to impact an ASR scheme in this aquifer. Water quality changes
during storage and the impact of storage period on recovered water quality were
investigated in the laboratory using ASR simulating columns, with storage times of 15,
20, 30 and 60 days. Water quality improvements such as biodegradation of disinfection
by-products, denitrification and sulphate reduction were observed. However recovered
water quality deteriorated with respect to iron, arsenic, manganese, total organic carbon
and nickel. These results, together with the review of regulations conducted as part of
decision support tool development, suggest that the current interpretation of the Water
Framework Directive requirements is overly restrictive and is deterring wider
implementation of ASR in the UK. Conclusions focus on the need for a more
appropriate approach to regulating ASR schemes, in particular, one which adopts a risk
based approach to determining water quality standards.
