This project involved a unique stormwater management issue resulting from an existing roof drain outlet buried 12-feet below existing grade. It was not feasible to raise the existing outlet so an innovative engineering solution was required to solve onsite drainage issues. The resulting design involved installing a 12-foot by 14-foot underground cistern on a reinforced concrete footing downstream of the building. The building roof drains were connected to the cistern through a new storm sewer network, and the outlet for the cistern connected to an existing storm sewer. The foundation system for the underground cistern was designed to allow for infiltration of storm water. The project was a success, as system is designed to completely drain and maximum stormwater elevations in the storm sewer system will be well below allowable freeboard relative to the buildings foundation.