 Secondly, having tanks 3-5 located at some distance from tanks 1-2 decreased risk to the whole installation.Thirdly, existing mature trees and the topography could be capitalised on to camouflage tanks 3-5 (tanks 1 and 2 relied on heavy steel cables and netting material as camouflage).Because tanks 3-5 were intended for the storage of crude oil they were constructed in reinforced concrete.