Complex sentence: An example might be an industrially-used site that can now be used legally for high-rise residential buildings, but would cost so much to clean up (remediate) that the value as currently used is higher.
Split into simpler sentences: An example might be an industrially-used site that is now legal for highrise residential buildings. However, the cost to clean up (remediate) the site is so expensive that the value as currently used is higher.