Contaminated Land and Aquifer Remediation

Wheathampstead, Uk

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In the early 1990s, Oceans-ESU Ltd (then ESU Services) were asked to remediate an industrial site in the South East of England. The site was formerly a pesticide research and development factory which had been a manufacturing base for a wide range of agricultural, horticultural and garden chemical products. The works also included an experimental division that tested and developed new compounds, some of which never became available on the commercial market.

The site had been bought by a large retail company who planned to develop it. Oceans-ESU were asked to carry out a contaminated land investigation to establish the nature and extent of any contamination. Research into the site included interviews with former factory chemists. From this information, a list of all the compounds that had been produced by the factory was drawn up, so that chemical analysis could be properly targeted. Extensive site investigations found that the soil and aquifer in the vicinity of the factory were contaminated with a wide range of pesticides, some of which had never reached the marketplace.

The site is located in a picturesque village, with residential areas close by. As such, any investigations and remedial works had to be conducted with care to minimize disruption. Furthermore, the groundwater in the area is an important drinking water resource, and the adjacent river is regarded as being one of high quality and potentially under threat from the movement of contaminated aquifer.
This reed bed treatment system was designed and built by Oceans- ESU in 1990 to remediate the site of a former pesticides factory.

The reed bed was used to remediate both the contaminated soils and the aquifer at the site. Aquifer remediation is still ongoing with a “pump and treat” system in place to feed the reed beds.

Very little was known at the time about the best way of dealing with the chemicals identified, or the likely long-term effects of them on the environment; however, it was clear that action needed to be taken.

Following an industry-wide consultation process that lasted almost two years, a solution proposed by Oceans-ESU was agreed by all parties involved.

Oceans-ESU designed and installed a reed bed treatment system to achieve two purposes:

  1. Remediation of contaminated soils from across the site
    Long term remediation of contaminated aquifer waters from below the site.
  2. Two pumps were installed to extract contaminated aquifer water and feed it to the reed beds. This provided water essential for the growth of the reeds and health of the reed bed system. In addition, aquifer remediation could be achieved alongside the soil treatment.

Once monitoring showed that water treatment was successful, and all Environment Agency requirements were being met, treated water was injected back to the aquifer.

Following the soil remediation, a proportion of the site has been sold for development with full certification from the Local Authority and the Environment Agency. With the help of Oceans-ESU, the landowners managed to make a significant financial profit from this environmental clean-up and re-sale of this site.

As well as protecting the aquatic environment, the reed bed also provides a valuable wildlife habitat in its own right. Even water voles (a protected species) have been observed making use of the resources this system provides.

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