The need to balance environmental impacts, emergency management measures, affordability, and a myriad of other difficult aspects of this project are important. Werrlein Properties won't be able to make every resident happy with their development project, but that shouldn't be the reason that the project is rejected. There will be change to Hyattsville, it isn't easy and will often be uncomfortable.
Despite the potential to be a great location for a new school, it isn't a political or fiscal reality at this time. Turning the building into a 100 unit apartment/condo will only aggravate the feared traffic concerns and makes and even greater change to the character of the neighborhood. While the historic preservation of old building is important, not every building is worth saving.
The issues that Werrlein Properties does need to address to make this property viable are the storm-water management, environmental impact, and flood mitigation concerns. The obvious place to start would be to only build outside of the 500-year flood zone, this would leave most of the upper property for development. To address the environmental impact I suggest utilizing local expertise and implement a better ecological transition from the Magruder Park bog into an expansion of the parks green/wild space on the lower property. Finally, the storm-water management issue must be addressed because the lower lot is one the lowest points in Hyattsville and it is not a matter of if but when there will be flash flooding. Green roofs, community or household cisterns, advanced bio-retention areas, and other methods must be implemented.
There are many dedicated and experienced people in Hyattsville, Werrlein Properties must continue to make use of their skills to help make this a project that is not only acceptable to the community but a proud achievement that makes Hyattsville an even better place to live.