Soil-bentonite mixtures are frequently used in barrier walls to aid in the control of groundwater flow across contaminated sites. These mixtures typically have low undrained shear strengths with values in the range of 7 kPa to 15 kPa. Issues can arise when infrastructure such as roads are subsequently proposed to cross over these barrier walls. Common practice is to add cement to increase the strength of the mixtures, however, this can be costly and can have detrimental effects on the permeability of the barrier wall. This paper presents an alternative to adding cement by using a reinforced soil capping beam to bridge across the barrier wall. Three design tools are utilised in the current assessment, namely: British Standard 8006-1 Design of a Reinforced Soil Embankment over a Void; a proprietary program used to model geogrid reinforced pavements; and the numerical software package Plaxis 2D.