Background
Cormac Construction were carrying out work on a Truro’s Eastern Park and Ride scheme in April 2014, extending the existing Park for Truro service into a cross city link.
Building on the success of the current Truro Park and Ride which operates from Langarth at Threemilestone, the service will provide a regular shuttle link through the city centre to Union Hill on Newquay Road.
The Overall Objective
During works, a large excavation was dug to capture all surface water runoff from the project site. These waters came into contact with recently stripped soil and general civil works prior to entering into the excavation. Clay and colloidal particles were present and unable to fall from suspension due to their poor settling characteristics. Prior to our involvement water had to be tankered off-site at great cost to the contractor.
Solution
In order to eradicate the slow settling particles from suspension, a 2 stage flow proportional chemical treatment system was rapidly installed to treat a flow rate of up to 100m³/hr. The Total Suspended Solids content of the water being discharged to the stream had to be less than 60mg/l, an objective that was comfortably met as a result of a flow proportional chemical pre-treatment.
