Evaluation

The final phases of Bristol Business Park  have succeeded in achieving the aims of both the planners and the developers: the innovative drainage system has prevented flooding from water run-off without compromising the appearance or commercial viability of the business park.

Maintenance is responsibly of the individual businesses on the site, which have been given specific maintenance schedules. Observations of the permeable paving system during and after heavy and prolonged storms have shown that only a negligible amount of water is discharged into the surrounding swales. This suggests that it is performing its intended water retention function well, although no formal water flow measurements have been taken. This permeable paving approach is now being replicated across South Gloucestershire.

A learning process

Although the scheme has delivered what both the planners and developers wanted, achieving the result was a learning process for the contractor. For example, the porous gravel was installed early on in the process and then protected with a layer of macadam, but the protective layer was punctured during the installation of the services, drainage and ducts. When the work was redone, the services, drainage and ducts were installed at an early stage to avoid later contamination of the porous gravel or damage to the impermeable membrane. The paving blocks themselves were laid towards the end of construction and care needed to be taken with topsoil and sand deliveries to avoid blocking the gaps between the blocks.

Access to information

Given the increasing demand for SUDS from the Environment Agency and local planning authorities, we are likely to see a growing number of innovative approaches like the one taken at Bristol Business Park. The long-term success of new and innovative drainage solutions depends upon contractors and building managers having access to information and expertise on how to install and maintain them.