Warning over dangers to water supply in brownfield remediation

Developers of brownfield sites have been warned that a lack of proper sampling and monitoring techniques could lead to contamination of water supplies and leave them with a costly bill to resolve the situation.

Dr Rob Fuller, Laboratory Commercial Manager at Southern Water Scientific Services, told edie news that developers could save money, and potential contamination, through a comprehensive sampling programme at the design stage for contaminants in the soil to see whether these could have a detrimental effect on new and replacement water pipes.

Permeation and accelerated deterioration of the pipe material can occur due to chemical reaction between pipes and contaminants in the ground in which it is laid. Such deterioration can also lead to permanent failures resulting in leakages and loss of water quality.

Recently, the large-scale development of brownfield sites, many of which contain contaminants, has resulted in the problems becoming potentially more significant.

Dr Fuller told edie that the danger occurs when developers wish to connect to the water supply. While there are strict government guidelines about laying supply pipes in contaminated, or remediated, land, the requirements for the surrounding land, through which pipes may run, is not currently part of the process.

Currently, there is no statutory requirement to undertake a full sampling programme of the soil and groundwater conditions along the pipeline route outside of the development. However, the possibility of the movement of contaminants through the soil may result in their presence in adjacent ground needing to be taken into account when making connections and selecting the right pipe material.

"Some materials are approved for use in pipes for drinking water, but not against all contaminants," Dr Fuller explained. "In this case you will need to know what contaminants are present before choosing the pipes. The materials approved for drinking water are good for many things, but they do not protect against all contaminants. They are susceptible to solvents and various organic pollutants, for example."

Dr Fuller said he frequently encountered developers and landowners who, whilst understanding the contamination issues on their site, appear to have no knowledge of the status of surrounding land.

He warned that, as approval from the local water supplier is needed at the design stage of projects before developers can connect to the mains, developers should check that the results of normal site investigations which are required as part of the planning process are adequate indicators of contamination when designing water services.

"It is all about transfer of risk," said Dr Fuller. "If the developer does not provide accurate or full details of the land conditions of the pipeline, then, should a problem occur at a later date, the water company would undoubtedly pursue the developer to resolve the matter. A situation that, potentially, could have a costly outcome."

Until planning permission is forthcoming, however, all money spent on sampling and consulting is considered pure risk from a developer's point of view, reducing their enthusiasm for comprehensive sampling.

This could lead to the wrong pipeline materials being chosen and some serious cost implications for the developer.

"Whilst the water supplier has no statutory duty to ensure that the water remains wholesome after it has passed a property boundary it will investigate and insist on remediation where a problem is found," said Dr Fuller. "It is vital that developers understand the potential risks and work with the water suppliers to ensure the best results for all."

With 478,000 new homes approved for development in the East of England alone and many more in such developments as the Thames Gateway, the need for comprehensive sampling could be greater than ever.

By David Hopkins



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