COS Benchbook for public access. The point information contained was mapped by the City of Springfield through differential leveling methods. This elevation data was collected at various times in the past several decades, and was recently verified for accuracy in the Summer of 2010. To verify accuracy, the existing differential leveled data was shot with GPS and benchmarks found to be errant were re-leveled by differential methods. These data are intended for use in engineering and citywide planning. There are no warranties that accompany this product.