INTEGRATING QUALITY OF LIFE BENEFITS WITH URBAN STORMWATER MANAGEMENT: A SUCCESSFUL CASE STUDY FOR A PHASE II COMMUNITY

Millions of dollars are to be spent over the next several decades implementing Phase II Stormwater Regulations, TMDLs, voluntary watershed management plans and habitat improvement programs. Urban stormwater management is becoming one of the centerpieces in these programs aimed to restore the beneficial uses of the nation's waterways. The City of Portage, Michigan pioneered a comprehensive approach to stormwater management designed to achieve multiple benefits in water quality improvement and quality of life for city residents. This was accomplished through the design and construction of a regional stormwater treatment system for a 1.9 km2 (0.7 mi2) urban drainage area within the highly developed urban core. The objectives of this approach targeted pollutant removal, mitigation of stormwater thermal impacts and hydraulic flashiness on the receiving stream, as well as expansion of existing trailways through the city's core recreational areas.The treatment system design combines several off-line stormwater treatment options, including a sediment pond, wet detention basin and wetland treatment cell. Monitoring results indicate the treatment system achieves 73% and 83% reduction of incoming loads of total suspended solids and nitrate + nitrite nitrogen, respectively. Results show that the 3-stage treatment design is also effective in reducing stormwater thermal loading to the coldwater-receiving stream by 45% compared to pre-construction impacts. The enhanced natural wetland treatment cell accounts for most of the thermal load reductions via infiltration and evapotranspiration. The dense canopy coverage and longer detention time of the treatment wetland allow water temperatures to reach ambient air prior to discharge into the receiving stream.Construction of this regional facility allowed the City to reclaim nearly 6.1 ha (15 acres) of previously non-taxable land for re-development by replacing several private, on-site detention basins that were poorly maintained and ineffective at pollutant removal and flow moderation. More than a mile of integrated scenic trailways in the new regional facility connects major retail and recreational facilities. These trailways allow access to the 10.4 ha (25.7 acres) comprising the stormwater treatment area that provides wildlife habitat, a restored stream corridor, recreational access, flood protection and opportunities for environmental education. This paper highlights: treatment system design; elements that influence its effectiveness and address Phase II Stormwater Permitting objectives; quality of life benefits, and; programmatic successes that secured public support for this 6.6 million effort.