Private Water Supplies - Case Study 2012/3

Borehole risk assessment

This case study relates to a risk assessment of a borehole supply. The local authority carried out a risk assessment in August following the Scottish risk assessment framework and the Environment Agency’s good practice guide for borehole construction. Although the design and construction of the borehole prevented ingress of surface water contamination, the risk score was determined as ‘high’ because the construction did not mirror exactly the illustrated example in the best practice guide. When this was explained by the local authority the supply owner contacted the well drilling company (a member of the well drillers association) who had carried out the works. The well drilling company then explained to the supply owner and the local authority that the methods used were equivalent to, or better than, those set out in the guide.

The Inspectorate’s risk assessment tool issued to local authorities in July is more flexible in its approach, allowing for innovation by focusing on best practice principles rather than adherence to particular examples in the guide. The Inspectorate continues to receive evidence of examples of unsatisfactory well construction and remediation practices, and this has been drawn to the attention of the Environment Agency with a view to widening awareness of the problem. In addition, the Inspectorate has written to the Well Drillers Association to encourage the industry to develop a British Standard for borehole construction that can be referenced by supply owners, local authorities and responsible service providers.