I’m finding myself more and more at odds with planners at work regarding willingness to extend certain private uses in public right-of-way. Wondering what folks like yourself as planners think, and wondering if you have similar situations and policies as a result. Here’s a typical scenario:
Developer wants to redevelop in an older part of town, aggregating several parcels of land with existing single family homes along a collector street. The proposal is to tear down the homes at around 5-6 d.u./acre and intensify the aggregated parcels with multi-family housing above 15 d.u./acre. The area as it exists with single family homes might be 25% impervious surface, but now with the proposal, 75% impervious. As a result, storm drainage water quantity detention requirements kick in, as well as water quality (neither of which of course was originally required back in the days of the single family development).
Generally, when the developer realizes the amount of land needed to set aside for storm drainage requirements and/or the costs associated with measures on the private side such as rooftop detention, there is a push from the developer to use the abutting public collector street as the system that will provide the water quality and water quantity detention requirements created in no small measure by the amount of additional impervious the development is proposing. The public street becomes an infiltration system where water passes through permeable concrete/asphalt. This is sold as well as being “green” in that water isn’t conveyed through storm drainage systems but is treated somewhat more at the source.
My opinionated view as an engineer is that this extends too great of a private benefit at the expense of the public. A developer should meet storm drainage requirements required to be mitigated within the developer’s property and not use the public space to do so. Certainly there’s a need to push for density in urban areas, in my view the need for more urban density should still place the burden on the developer to mitigate their own impact. Certainly there’s a push for “green streets” everywhere, but from what I’ve seen, streets that infiltrate drainage seem to be for drainage that occurs within the street, not from impacts created on private property being pushed out into the public street system.
Do you have a policy or viewpoint regarding how the public street system can be used to mitigate storm drainage requirements caused by development/redevelopment? Would love to get input on how you might (or might not) allow private impacts to be mitigated within the public realm.