Even if the Sphere itself is practically infinite the area you live in is not. The resources are finite and delicate and only by studying them will a Culture learn how to best manage what they have as long as they can. Environmental Management allows a Culture to create the means of reducing and storing the waste products of their population and cities in manageable and safe locations. Any Culture that plans to grow into a mighty civilisation is going to need to investigate this technology path in depth.

It allows the creation of the Landfill Dump building - which is a good first step on this path.