Sewage works have traditionally been located on poor quality low lying ground which often means a high groundwater level. Sewage plants rely on gravity and so require deep excavations for manholes, connecting pipework, pumping stations and hoppers. Groundwater may suffer legacy contamination due to historic leaks. Many sewage works require updating to meet increased demand and more stringent outfall effluent criteria. Where space is limited this can require the existing works to remain fully operational while other effluent streams are updated. WJ has experience of working on both new build and upgrade schemes for sewage and water works across the UK. Over the years our full range of techniques has been deployed on a range of projects to tackle the particular hydrogeological conditions and prevailing site constraints.