 To find out more about that second option, we talked to Catherine Kelly, the assistant director of engineering and construction for the Narragansett Bay Commission. We're trying to promote infiltration of stormwater into the ground rather than being directed to our combined system. After all, if rainwater never goes into the sewers at all, the system can't get overwhelmed. That makes sense, but how do we do that? Part of the problem is that we've paved over so much land with streets, sidewalks, driveways, and parking lots.