Kurt Mandl was a senior member of the Federation's Terraform Command during the mid-24th century who was assigned as director of the terraforming mission, coordinated from the Velara Base, on the planet Velara III.
Unknown to them, the planet was not lifeless and their terraforming was actually killing the silicon-based lifeforms that inhabited a thin layer of water between two layers of soil. When one of the terraformers was killed by a sabotaged laser drill, the scientists contacted the USS Enterprise-D. Data and Geordi La Forge soon discovered the microscopic lifeforms and learned that they were attempting to communicate. After gaining understanding of the consequences of their actions, the scientists eventually took the necessary steps to avoid further harm to the native lifeforms. The planet was placed under indefinite quarantine and the scientists were transported to starbase aboard the Enterprise. (TNG: "Home Soil")