The Conversion Unit, Tricel Sewage Treatment Plant Problem & Solution
Orford Ness is a 10 mile shingle spit of land off the Suffolk coastline and is separated from the mainland by the River Ore. Orford Ness is the largest vegetated shingle spit in Europe and is both a Site of Special Scientific Interest (SSSI) and is also a RAMSAR Site.
Top secret military testing was carried out at this designated Outstanding Area of Natural Beauty during both World Wars and Orford Ness was home to both the Ministry of Defence’s Experimental Flying Research Station, and after World War 2, the Atomic Weapons Research Establishment.
Orford Ness in Suffolk is now owned by the National Trust and is open to the public for parts of the year. Due to an ineffective septic tank soakaway system serving the waste water facilities on the Ness, the National Trust asked Mantair to investigate and provide a solution to the problem, taking into account the wide variation in waste water flow between winter and summer months.
Prior to the design element of the project, Mantair carried out a full site investigation including a detailed land survey for unexploded ammunitions and underground services. Following the various preliminary site surveys, Mantair liaised with the Environment Agency, English Nature and Suffolk Coastal District Council regarding the project to determine an acceptable wastewater treatment solution.
Taking into account that Orford Ness is an internationally important site for nature conservation, the Environment Agency and English Nature accepted Mantair’s waste water treatment proposal which comprised two sewage treatment systems and a flow splitting chamber which allows the flow to be diverted to either of the two systems. For low season during winter, a Mantair septic tank conversion system was fitted within the existing septic tank, converting the tank into a fully functioning sewage treatment plant. In summer the Ness is open to the public and the waste water flow increases substantially. A 42PE Tricel packaged sewage treatment plant was installed to cater for the increase in flow during summer.
The Orford Ness project in Suffolk posed significant challenges to Mantair engineers as there is still dangerous debris buried on the Ness, including bombs, and the only access onto Orford Ness is from Aldeburgh along shingle beach on a Unimog vehicle, or from Orford Quay on a landing craft. Timing was also crucial on the project as the water table on the Ness is affected by the tide and all excavations had to be carried out within a certain time frame.
Despite the complexity of the Orford Ness project, the pre-planning and experience of the Mantair engineers ensured that the project was completed efficiently and without any problems.
