July will see the long awaited implementation of Section 57 of the Environment Act. This places a duty on local authorities to take account of all areas of potentially contaminated land that fall within their boundaries.
A major issue for local authorities is the identification and risk categorisation of sites. Reading Borough Council decided to act early and commissioned the Babtie Group to carry out a two-year study to determine the nature of its likely liabilities.
Budget limitations mean the study is not intended to provide a full register of potentially contaminated land, nor is it comprehensive. Instead, it is being used to assess the scale of the problem across the borough.
This will allow future government funding to be specifically targeted towards any risk categorisation of sites, specific investigations or remediation that may be necessary.
Babtie Group has completed the first part of the study. Up to 600 potentially contaminated sites have been identified, with 150 of them categorised for potential risk based on guidance in the Department of the Environment Contaminated Land Report No 6 (1995), although a site walkover was not included in the survey.
The study allowed Reading Borough Council to identify the extent and nature of the sites with potential contamination issues before legislation came into force.
To aid categorisation and achieve consistency, Babtie adopted a qualitative risk assessment approach. Initial categorisation could therefore provide a means of determining those sites likely to pose the greatest threat and requiring more detailed desk study or possible site investigation.
Each site was assigned a specific risk category based upon the CLR6 guidance (Table 1). Table 2 summarises the number of sites which fall into these categories after work to date.
Because a site walkover was not included in the initial study, it was not always possible to assign risk to the four categories of CLR6. Babtie developed supplementary categories which took account of uncertainties which became evident as the study progressed. This resulted in 10 different categories. It is intended to reduce these to the original four, once more information or investigation data becomes available from future studies.
Risk assessment data was put into information matrix sheets and then plotted on Babtie's GIS to map the sites. A number of the top-ranking sites will now undergo a site walkover and closer examination to determine whether the initial risk categorisation can be confirmed or reduced.
One of the main difficulties of the study has been the inability to find a complete series of historical maps for the area at a scale that would provide the detail necessary for this sort of survey - 1:1250 or 1:2500. Smaller scale maps do not provide enough detail for site identification and risk categorisation.
Despite this, and with limited funding, the study has meant that Reading Borough Council is able to get a head start before legislation comes into force. Potential liabilities have been identified and strategies to deal with these can be developed and implemented.
More importantly, the council can now concentrate efforts on targeting risk category 1 sites when government funding becomes available. The information will also allow the council to establish potential cost requirements for this work over the next 12 months.
This is just the start of a major initiative. The study needs to be expanded to complete the the risk categorisation and inspection of all sites initially identified.