Split-flow Stormwater Management Strategy Design Feasibility and Cost Comparison

This dissertation develops a new distributed split-flow stormwater management strategy and compares its site design feasibility and construction cost to existing stormwater management methods. The purpose of the split-flow strategy is to manage stormwater by preserving predevelopment flows in terms of rate, quality, frequency, duration and volume. This strategy emulates the predevelopment hydrology: it retains and infiltrates additional runoff volume created by development by using bioretention and paired weirs as proportional flow splitters connected to small infiltration facilities distributed throughout a site. Results show that 1) the distributed split-flow stormwater management strategy can provide a higher level of environmental protection at comparable construction cost to existing detention-based methods, 2) split-flow systems are less expensive to construct than current truncated hydrograph-based bioretention and infiltration systems and 3) non-point source water pollution-reduction objectives, currently achieved with either detention with first flush or comparable bioretention and infiltration systems, could be achieved in a more cost-effective manner using distributed split-flow stormwater management strategy.