Meeting Municipal Surface Water Needs During Intense Redevelopment

Description

The city of Shoreline, Washington is experiencing rapid redevelopment within upzoned residential areas that are served by aging and informal drainage systems. Many redevelopment projects occur on parcels that fall below the size threshold for triggering flow control requirements, resulting in additional impervious area and higher runoff rates during large rain events. Over time, the increased runoff rates may exceed the capacity of the municipal storm system or destabilize the receiving streams. To address these concerns, the City of Shoreline is taking action to: 1) adopt stormwater permitting policies and flow control requirements that are more stringent than the Washington State standards, 2) perform surface water modeling to evaluate system capacity and identify potential conveyance improvements, 3) explore opportunities for regional detention facilities, and 4) maximize the benefits of green stormwater infrastructure through integrated planning with other City departments. This presentation will describe the contributions of each of these elements and the outcomes of the initial planning studies.