Complex sentence: The Washington State Department of Transportation decided to halt all construction efforts relating to the graving dock on December 21,2004 and is currently undertaking only those steps required to ensure the preservation of remains and artifacts already uncovered by the construction.
Split into simpler sentences: The Washington State Department of Transportation decided to halt all construction efforts relating to the graving dock on December 21,2004. Since then it has worked to ensure the preservation of remains and artifacts already uncovered by the construction.