Many years ago the Brandywine Zoo was free. The cache is located next to the origional entrance to the zoo. Now it is a service entrance since a new entery point was constructed. Be sure to check out the lama that are just inside the fence. There are no fees for Brandywine park. There is a small fee to visit Brandywine Zoo. The cache is outside of the zoo proper so you do not need to enter the zoo.
DGT Brandywine Zoon (Coordinates) - N 39° 45.295 W 075° 32.917