This afternoon, Susan and I met for a second time with a subcommittee to discuss implementation of the River Terrace Concept Plan.  The subcommittee is focusing on development challenges and needs in 2014 and 2015.  The liveliest discussion this afternoon was generated by a quick review of the draft Stormwater Master Plan, which is now under review.  Managing stormwater in River Terrace is challenging, given the absence of existing facilities, low-infiltration soil conditions, steep slopes in the south, degradation of natural water courses, and a dynamic and evolving regulatory environment.  The current draft Stormwater Master Plan shows large, or “Regional” detention facilities in the north part of RT to serve multiple developments, along with proposed “Low Impact Development Approaches” (LIDA) in the south, to detain and treat site runoff prior to release the conveyance system.  The subcommittee raised questions about both assumptions.   Regional facilities are expensive and currently lacking a funding source.  They also are designed to serve multiple properties, but properties that are not adjacent to the regional facility cannot be developed until it is in place.  This could limit development of smaller projects and distant sites, according to subcommittee members.  They said LIDA treatments are also expensive, if needed on every site.  Additionally, they require regular maintenance to function properly, and maintenance can be challenging for homeowners and city public works crews.  Finally, a point was made that sometimes stormwater that runs through a LIDA facility is “double treated.”  The subcommittee is raising the kinds of questions that will help the City of Tigard craft a Stormwater Master Plan (the first one in Tigard) that balances water quality management with development feasibility.  We have a lot to figure out here, and there will be plenty more to come on this issue!  Stay tuned…