Geotechnical engineering has a crucial role to play in enhancing sustainability due to its pivotal role in the construction process where potentially impacts are highest. Currently, there is a lack of methodologies for assessing geotechnical projects that truly encompass the three core pillars of sustainability. A robust system is required which offers an holistic approach that is both flexible and easily understood, whilst not being biased towards rewards or is prohibitively costly. In addition, ‘tool fatigue’, whereby a system is generated but never used, must be avoided. After a detailed evaluation of the systems available, the SPeAR® framework was selected. Following detailed discussion with a variety of practitioners, the methodology was significantly adapted to make it applicable to geotechnical problems and ensure that geotechnical engineers can understand and use it with relatively ease. The new version, called ‘GeoSPeAR’ in this thesis, allows for greater communication between masterplanning and geotechnical engineering via their common base, thus avoiding a potential barrier to greater adoption of more sustainable practices through the construction cycle. Three case studies demonstrated the assessment of the ‘GeoSPeAR’ methodology. These showed the practical application of the system and how this effectively supports geotechnical engineers in embedding sustainability into projects.