Deep beneath Fremont and Ballard, a massive tunnel is the focus of a new plan to reduce storm and sewage runoff. During torrential storms, the current system becomes overwhelmed and polluted runoff flows into the Lake Washington Ship Canal, and eventually into Puget Sound. In the future, the 2.7-mile tunnel will capture excess runoff and send it to the West Point Treatment Plant instead. Producers Randy Eng and Pete Cassam have more on this project designed by Seattle Public Utilities and the King County Wastewater Treatment Division.