Caustic Soda Soil & Water Remediation & Demolition Works
Client: Alcan Chemicals Ltd.
Consultant; RPS Plc
Challenge: Address contamination including elevated pH levels up to 14 pH arising from the use of caustic soda within the site processes for producing allumina, hydrocarbon contaminated material from burried heavy fuel oil tanks and localised diesel spills.
Applied technology: Installation of a 33,000m2 engineered cap. Excavation and removal of material to the Alcan owned landfill site, Whinnyhall. Excavation & removal of burried tanks and bioremediation of soils.
Remediation criteria: Reduce pH and hydrocarbon contamination levels to below 10pH and 500mg/kg respectively.
Validation: Ongoing monitoring by consultants.
Soilutions managed all remediation activities, including site sampling and testing, liaison with client, managing site contractors, budgeting and evaluating works. The Client was sufficiently impressed with the quality and management of Soilutions activities that our remit was extended to include the project management of all demolition activities on site.
Site constraints included a culverted burn crossing the site and discharging directly into the Firth of Forth during a very wet summer. This combination presented additional challenges controlling site surface water run off.
Installation of a 33,000m2 cap across the site involving crushing, screening and placing of 500mm of graded material incorpoating a 300mm base layer to form a capillary break. Placing a bentonite geotextile membrane and covering with 500mm of graded material.
Length of Project: Consultation: Three months On Site: November 2003 – August 2004