BMT Cordah joined up with Penspen Onshore and Offshore Pipeline Consultants (www.penspen.com) to provide environmental consultancy services associated with the environmental risk linked to the historical disposal of produced waters in remote locations within the Libyan Desert.

Since the 1960’s, produced water generated through the separation of crude oil within the producing fields, has been discharged into a series of unlined, disposal pits.  BMT Cordah were contracted to determine the environmental risk posed by historical disposal activity and to design remediation measures, as appropriate.

 
An illustration of a typical disposal pit is provided below:

 

Alongside the disposal pits, were numerous “overflow pits” used to the temporary storage of crude during periods when operational difficulties were experienced.  Such pits were also unlined and the potential existed for material to be removed, treated and placed back into the process stream.  An example of an overflow pit is given below:

The project area consisted of a flat, open desert environment which lies approximately 150 km from the Mediterranean coastline which receives almost no rainfall.  There are no significant ecological features and no naturally occurring surface waters.  Sandstorms are known to occur between the months of March to May, and a typical day outside of this period is characterised by strong sunlight, high temperatures and low cloud occurrence.

The historical use of unlined pits for the disposal of produced water and as temporary storage for crude, has the potential to result in soil and groundwater contamination in the form of Heavy Metals, Hydrocarbons, Naturally Occurring Radioactive Material (NORM) and residues from process chemicals.  In summary, the environmental risk remained unknown and needed quantitative assessment.

During the final stages of the study, a detailed assessment of remediation options was undertaken, to include CAPEX, OPEX, technical viability and other factors.  One optimum solution considered included a ‘boxing-in’ approach where material is enclosed within an above ground structure to ensure that contaminated sand could not in the future, be mobilised through wind erosion, into the atmosphere.  

Results of the study were incorporated into an Environmental Impact Assessment process, resulting in an Environmental Statement.