The new hospital in Enniskillen, in Northern Ireland, is enclosed in an area formerly occupied by an old farm, and it is not part of any developed urban area. The location of the work caused two drainage problems that should be solved.

• What to do with sewage water produced by the temporary site facilities.
• How to comply with the requirements of NIEA (Northern Ireland Environment Agency) to prevent spillage of high levels of solid waste from the work into the runoff water, avoiding their pouring into the Lough Erne’s hydraulic system.

We must stress that the problem was even worse due to the rainy weather in that area.

The solution for the first problem - the sewage water - was achieved by constructing a temporary sanitation network connected to a grease trap interceptor, and a sewage treatment plant. By means of the temporary drainage system, the work was able to cleanse and purify sewage water before it was discharged to the drainage system of the work . Moreover, the solid waste was monthly collected till the temporary sewage system was connected to the local sewage network.

In the case of drainage water and runoff water, the layout of the work allowed us to channel them to a pond where they were treated before its canalization to the nearest lake. A rudimentary but absolutely ecological filtering system was built. It consisted of a channel with bundles of straw on its bottom, through which the water from the main pond was canalised to become filtered, and led to a smaller pond where that water was decanted. Water purity and its pH parameters were measured weekly, in order to ensure that the discharge parameters were achieved. During the execution of the works, there were 175 PH measurements, all of them performed by NIEA, and they never exceeded the authorized limit for solid waste concentration, nor the permitted pH.