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Why are rain gardens in conjunction with drywell decommissioning such a major focus? []?R -121 Due to the discontinuous nature of the stormwater conveyance in this Basin, it was considered impractical to extend new piping to each of the drywells to be decommissioned. Rain gardens are proposed as an alternative solution for isolated drywells or clusters of drywells that are of considerable distance from an existing stormwater pipe and for which no piped extension is planned. Does drywell decommissioning need to be linked to proposals for new sidewalks, wider streets, replacing existing drainage swales? Could existing swales be "spot renovated" instead? [RR -171 Decommissioning of drywells is not necessarily linked to proposals for street improvements. Staff acknowledges that the RR -SC Plan conveys that impression, and will clarify the strategy in that regard. It is most likely that the regulatory timeline for decommissioning drywells will require action by the City and County on all drywells within the next 10 -12 years, necessitating the construction of isolated rain gardens and piped connections to the existing system — depending on the specific circumstances for each drywell. In the case of an isolated UIC decommissioned via a rain garden, the rain garden could be configured longitudinally, oriented parallel to the street and coincident with the existing swale(s) if the swale could be engineered to function adequately to infiltrate the City's flood control design storm. Adequate surface area and infiltration rates in a rain garden must be achieved in order to handle the flows currently being managed by a drywell. Where local street improvements occur in the next 10 -12 years, and if the street improvement is in an area with several public drywells to be commissioned, it makes sense to consider incorporating the management of the roadway runoff via rain gardens into the plan to decommission the UICs. Topic; Local Green Street Design Concepts • Would add too much new impervious area, alter character of the neighborhood, and result in loss of street trees and other vegetation. Would involve costly assessments; who pays? Need more discussion and public review before implemented [SC -131, [RR -31, UMA Staff's objective in developing the local green street concept drawings was to provide alternatives to traditional "improved" local street sections (which include curbs, gutters, pipes). The green street concepts address problems and opportunities inherent in a discontinuous stormwater system, rapidly draining soils, flat topography, and shallow groundwater. They also incorporate feedback received from the RR -SC community groups on maintaining narrower streets and utilizing green infrastructure. The concepts are intended to be used as a starting point RR -SC Stormwater Basin Plan Comments Pg.13 of 17