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1 2 3 USING GREEN INFRASTRUCTURE TO 4 MANAGE URBAN STORMWATER QUALITY: 5 A Review of Selected Practices and State Programs 6 7 8 A DRAFT REPORT TO 9 THE ILLINOIS ENVIRONMENTAL PROTECTION AGENCY 10 11 by: 12 13 Martin Jaffe, Moira Zellner, Emily Minor, 14 Miquel Gonzalez-Meler, Lisa Cotner, and Dean Massey, 15 University of Illinois at Chicago 16 17 Hala Ahmed and Megan Elberts, 18 Chicago Metropolitan Agency for Planning 19 20 Hal Sprague and Steve Wise 21 Center for Neighborhood Technology 22 23 Brian Miller 24 Illinois-Indiana Sea Grant College Program 25 University of Illinois at Urbana-Champaign 26 27 June 24, 2010 28 29 30 31 32 This research report was funded by the 33 American Recovery and Reinvestment Act of 2009 34 35 36 1 1 2 2 1 2 TABLE OF CONTENTS 3 4 ABSTRACT………………………………………………………………..…………..5 5 6 EXECUTIVE SUMMARY………………………………………………….….....…..7 7 8 CHAPTER I: INTRODUCTION…..…..………………….………………….…......21 9 10 CHAPTER II: THE EFFECTIVENESS OF GREEN INFRASTRUCTURE…..27 11 Indicators of Effectiveness…………………………………………….………..28 12 Sources of Data for Assessing Green Infrastructure Effectiveness…….……….29 13 Green Infrastructure Performance…………….……………………………........31 14 The International Stormwater BMP Database………………………………......34 15 Sources of Variation……………………………………………………….…….36 16 Maintenance and Effectiveness………………………………………….….…...38 17 Conclusions……………………………………………………………….……...39 18 19 CHAPTER III: FUNDING GREEN INFRASTRUCTURE…………...…………..41 20 The American Recovery and Reinvestment Act………………………….……...41 21 The Cost-Effectiveness of Green Infrastructure………………………………....43 22 23 CHAPTER IV: CURRENT PRACTICES……...…………………….…….…...….51 24 The Illinois MS4 Program…………………………………………….……...…..51 25 Local Programs……………………………………………………………….….54 26 Local Program Transferability…………………………………………….……..63 27 State Programs…………………………………………………………….……..69 28 State Portfolio Standards…………………………………………………….…..93 29 30 CHAPTER V: RECOMMENDATIONS…………………...………….…..…,…....101 31 Performance Standards………………………………………...………….……101 32 Administration……………………………………………………...…….……..102 33 Applicability………………………………………………………...….……….102 34 Funding Green Infrastructure………………………………………....………...103 35 Maintenance……………………………………………………,,,…….…….….105 36 Emerging Green Infrastructure Practices………………………………………..106 37 38 APPENDIX I: GREEN INFRASTRUCTURE AND 39 HABITAT IMPROVEMENT………………………………………...……...…….…109 40 Infiltration Areas and Buffers…………………………………………………...109 3 1 Constructed Wetlands…………………………………………………………...111 2 Detention/Retention Areas………………………………………………………113 3 4 APPENDIX II: SUCCESSFUL GREEN INFRASTRUCTURE 5 PROJECTS IN NORTHEASTERN ILLINOIS………………………..…………..115 6 7 APPENDIX III: DATA FOR PERFORMANCE ANALYSIS………..…...…...…119 8 9 APPENDIX IV: ACKNOWLEDGMENTS………………………………………...131 10 11 REFERENCES……………………………………..……………...……….…………133 12 13 4 1 2 3 ABSTRACT 4 5 Green infrastructure practices, for purposes of this study, are urban stormwater management techniques 6 that rely on natural systems to retain more stormwater on-site through infiltration, evapotranspiration and 7 harvesting for reuse. Implementing green infrastructure practices helps attenuate nutrients and other 8 pollutants and reduce runoff volumes and peak flows. Based on our review of peer-reviewed scientific 9 reports and articles, we found that, on average, many of these practices are as effective as conventional 10 on-site detention basins in reducing total suspended solids and total nitrogen being discharged to 11 waterways and that they can also reduce runoff volumes and peak flows discharged to urban streams, 12 reducing erosion, sedimentation and flood risks. Using an economic model, we also found that using 13 green infrastructure can result in substantial savings in both construction and life-cycle costs when 14 compared to using conventional infrastructure to manage runoff in suburban, urban residential and 15 commercial projects. Research addressing the valuation of ecosystem services also suggests that using 16 green infrastructure can provide significant indirect economic benefits, as well, by increasing the amount 17 of open space, vegetation, habitat and groundwater recharge occurring in developed areas. Since there is 18 considerable experience in using green infrastructure in northeastern Illinois and in five other states we 19 surveyed -- and since green infrastructure is already required under the state‘s General NPDES Permit 20 No. ILR40 (―the MS4 permit‖) -- we conclude that promoting the greater use of these practices would be 21 a cost-effective way for Illinois to improve urban stormwater management programs and the water quality 22 of our lakes and streams. It would have the additional benefit of helping municipalities covered by the 23 MS4 permit to meet their legal responsibilities. 24 25 Based on these findings, we recommend that IEPA consider the following: 26 27 Adopt a set of state-wide minimum volumetric standard for urban runoff, which would vary 28 based on site conditions; 29 30 Phase-in green infrastructure practices over a number of years, such as by adopting a portfolio 31 standard similar to the one already being used by Illinois for renewable energy; 32 33 Implement these practices in all new development, in redevelopment and major maintenance, 34 repair and replacement activities undertaken by both public and private parties; 35 36 Earmark funding for green infrastructure projects in state revolving loan funds, and develop a 37 simple and transparent method for prioritizing these projects; and 38 39 Encourage county and municipal stormwater management agencies to charge fees for providing 40 stormwater management services, including managing and maintaining stormwater facilities, with 41 the use of green infrastructure practices treated as a credit against such fees. Periodic 42 performance monitoring and reporting should be required to retain any credit earned for using 43 green infrastructure practices. 44 5 1 2 6 1 2 EXECUTIVE SUMMARY 3 4 I. INTRODUCTION 5 6 Stormwater discharges from urbanization remain a significant water quality issue in Illinois. Impervious 7 surfaces, such as the roofs, alleys, roads, sidewalks and parking lots characteristic of urban development, 8 change the hydrology of cities compared with undeveloped areas. Rain is unable to infiltrate on site, and 9 the resulting stormwater becomes runoff. Runoff and flooding contributes to erosion, combined sewer 10 overflows, sedimentation, and nonpoint source pollution and threatens human and ecosystem health. At 11 the same time, the lack of infiltration prevents our groundwater resources from being recharged, which in 12 turn reduces the ability of the aquifers to contribute to and maintain the baseflow rates and water levels of 13 our urban lakes and streams. 14 15 Our conventional stormwater systems – structures such as curbs and gutters, storm sewers and detention 16 ponds – are inadequate to handle our future (and in many places, current) stormwater management needs. 17 According to the Illinois Environmental Protection Agency (IEPA 2009), 1,218 stream miles are already 18 impaired by urban runoff and storm sewer discharges. The National Research Council (2009) and the 19 Center for Watershed Protection both found a direct relationship between urban land cover and the 20 biological condition of downstream receiving streams, confirming that the alterations in hydrology caused 21 by urbanization poses severe threats to the nation‘s waterways, and suggested that ―a number of 22 additional actions, such as conserving natural areas, reducing hard surface cover (e.g., roads and parking 23 lots), and retrofitting urban areas with features that hold and treat stormwater are recommended.‖ 24 25 Green infrastructure practices use natural systems to manage urban stormwater discharge to waterways 26 through preserving and mimicking natural pre-development hydrology.1 Green infrastructure practices 27 address the specific stormwater management goals of reducing runoff flow rates and minimizing the 28 pollutant loads entering waterways, the same goals addressed by conventional stormwater infrastructure. 29 But it also offers additional valuable community benefits not provided by conventional infrastructure, 30 such as groundwater recharge, runoff volume reduction, improved air quality, temperature moderation 31 and associated energy cost savings, increased open space for recreation and wildlife habitat and increased 32 land values. Green infrastructure can be applied on the site, neighborhood, or regional scales. On the 33 regional scale, green infrastructure can be an interconnected network of natural areas. It includes the 34 floodplains, wetlands and other natural and constructed areas that use predevelopment hydrological 35 systems to store, infiltrate and evaporate large quantities of stormwater, protecting developed areas from 1 Section 5 of PA 96-0026 defines “green infrastructure” in part as “any storm water management technique or practice employed with the primary goal of preserving, restoring, or mimicking natural hydrology. Green infrastructure includes, but is not limited to, methods of using soil and vegetation to promote soil percolation, evapotranspiration, and filtration.” Green infrastructure practices have also been called “best management practices (BMPs),” “stormwater control measures (SCMs),” or “low-impact development (LID) practices” by various practitioners. We deem all these phrases to be functionally synonymous, and will employ the phrase “green infrastructure practices”
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