McArdle Stabilisation recently completed a ground improvement contract on the first phase of the new Colchester Barracks project in Essex. The design and build contract, for LaganKeltbray, involved stabilising 60,000m 2of site-won materials for roads, car parks and parade grounds with lime and cement.
Designed by Babtie, the 300mm thick stabilised subbase layer was specified to have a minimum CBR of 50%, achieved using a blend of lime and cement with an average total binder content of 5% by weight of the dry density. Main contractor for the project was Sir Robert McAlpine for client the Ministry of Defence.
Siltbuster units are mainly used for removing solids from groundwater or site runoff but for the Gloster site a standard separator was configured to operate as a dedicated oil/water separator.
Contaminated water was pumped directly to the Siltbuster and processed though its main separation and oil retention compartments to remove the hydrocarbons present in the groundwater. With 99% of hydrocarbon removed, the treated water was re-used on site without the cost of off-site water disposal.
The captured petroleum hydrocarbons were drained from the unit and disposed of.