window wells filling up in heavy rain

When a heavy rain comes and the sump pump kicks on, the window wells in our basement fill with water and if we don’t bail it comes through the window. There is a pipe in the bottom of the well. What is it and how can I stop the problem? We have added dirt on the outside to slope it better and tar on the well to stop any leaks. Now we are at a loss and don’t know what to do next. Please help.
Thanks.