I would say that my big question is this. When they installed the new perimeter drain and dug the trench, how did they not see this and offer you a solution? Wherever the water is coming from into this pit, it should have been incorporated into the water-guard system.
On a separate note, anyone in New England with an open basement waterproofing system should have a radon test. The water-guard system is just that. It leaves gaps around your basement to take in water from wall leaks, etc. These gaps create an easy path for harmful levels of radon to enter your home.
Visit http://massachusettsradonmitigation for more information about radon.