What would happen if the relocation of Cambridge WWTP did not take place?
If the existing WWTP were to continue operating at the same location, rather than be relocated it is assumed that:
Fully treated flows
The transfer of waste water from Waterbeach via the proposed pipeline would be required even if the relocation of Cambridge WWTP did not take place. This would be delivered by the regulated part of Anglian Water Services.
In due course revised Environment Agency permit limits would be set, these would be similar to those proposed for the relocated WWTP (described above). Flows to treatment at the existing WWTP would be the same as at the proposed WWTP and therefore the volume and quality of final effluent (after being fully treated through the WWTP) entering the River Cam would be the same as the proposed relocated WWTP has been designed for.
Combined sewer outfall
The frequency of untreated stormwater entering the River Cam from the combined sewer outfall at Riverside car park several km upstream from the existing Cambridge WWTP would be more frequent without the storage capacity provided by the proposed WWTP’s 2.4 km long 2.4m internal diameter tunnel.
Stormwater storage
The frequency of partially treated stormwater entering the River Cam from the outfall at the existing Cambridge WWTP would be more frequent without the storage capacity provided by the proposed WWTP’s 2.4 km long 2.4m internal diameter tunnel.
The level of partial treatment at the existing WWTP, (screening and some settlement in temporary storage), at the existing WWTP is identical to the design of the proposed relocated WWTP.