In 2000, local building company Bussey & Armstrong bought the site of Darchem, the former Darlington Chemical & Insulating Company. Established in the 1920s and demolished in 1995, all that was left of the factory was a vast tip of calcium carbonate, a chalky by-product of the process of making pharmaceutical pills. Though this area was safe, it wasn't suitable for housing. Instead, Bussey & Armstrong decide to turn the 30-acres which formerly housed the factory into a public park.

The Westpark Nature Reserve was formally opened in 2005 and is continuously growing, creating a lively park that welcomes both residents of the surrounding homes as well as visitors from other areas in Darlington.