The forces and complex interactions that hinder and promote the application of sustainable infrastructures are discussed along with changes that are needed in our economic-mindset for evaluating project costs. Some existing sustainable projects result from favourable economics. However, many fall in the trash basket as a result of so-called unfavourable economics. One of the key driving forces for engineering sustainability is innovation, and regulations have historically been the driving force for innovations. Recently formulated effluent standards for a major municipal wastewater treatment plant (300 MGD) are pushing the envelope by making the effluent a recoverable resource. These costs have a major impact on service fees and force the development of innovations in wastewater treatment and the handling of combined sewer overflows (CSO). Economic, social and design changes are recommended for wastewater treatment facilities to support sustainability in private and governmental infrastructure programmes.
Keywords: cost/benefit, driving forces for sustainability, groundwater recharge, impediments to sustainability, regulations, sustainable infrastructure, water management