These studies were designed to support Environmental Permit applications for revised surface water management and discharge to ground. The project was undertaken in partnership with waste and hydrogeological specialists at Norfolk County Council (NCC).
An initial screening exercise was undertaken to prioritise sites with the highest environmental sensitivity, relating to the hydrogeological and hydrological conditions. Sampling of surface runoff was undertaken at three of the sites to obtain site specific data which could then be applied to all 16. Working with NCC we developed preliminary drainage solutions. We then undertook detailed hydrogeological modelling using Consim and the Environment Agency’s Remedial Targets Worksheet to assess compliance of the measured concentrations of hazardous and non-hazardous substances, respectively, with the Environmental Permitting Regulations (which implement the Water Framework Directive). Subject to the risk assessment results, the preliminary solution was then retained or redesigned.
As the household waste recycling centre (HWRC) sites are generally small, isolated sites in rural locations, it was essential to develop low cost, sustainable solutions that could run with low power inputs, low maintenance and low nuisance factor.
Other challenges included ensuring that the Environmental Permits were obtained in a reasonable timescale to allow construction to proceed within NCC’s planned programme.
One of the simple drainage solutions incorporated grassy swales for silt removal followed by infiltration through organic rich soil and natural material which was appropriate for sites with a thick unsaturated zone. This innovative solution, not previously used on local authority HWRC sites, has proved to be a sustainable, cost-effective solution.
We liaised with both the EA’s Permitting Team and technical specialists before and after submission to avoid or minimise delays in the determination of the Environmental Permits. To support the submissions we supplied additional information including cost-benefit assessments for various control options, where required.
Value and benefits
The innovative solutions we developed avoid the need for expensive treatment systems, storage tanks, pumps and associated operation and maintenance costs, demonstrating the benefit of undertaking a well-considered risk assessment.
We have a good understanding of the Environmental Permitting system and the requirements of the Environment Agency which led to a streamlined, efficient process for obtaining the permits.
A collaborative working relationship with NCC resulted in an efficient solution design as the various team members were able to provide specialist inputs in their own fields, resulting in minimal redesign work during the process.