Urban BMPs: Are We Playing on an Equal Field?

Nov. 1, 2001
Since the Clean Water Act (CWA) was created in 1972, clean-water programs have tried to make the waters of the United States “fishable and swimmable.” The focus of these efforts has been on reducing pollutants that come out of the end of pipes from industrial and municipal wastewater plants. The current national and state emphasis is now focusing on nonpoint-source pollution. Forty percent of US waterways are impaired, many in urban areas.The 1972 amendments to the Federal Water Pollution Control Act prohibit the discharge of pollutants to US waters from a point or nonpoint source unless the discharge is authorized by a permit issued pursuant to the National Pollutant Discharge Elimination System (NPDES). Municipal separate storm sewer systems (MS4s) and all system components (public and private) that convey urban stormwater runoff to the municipal system are part of a municipality’s NPDES stormwater permit system (Section 402[p][3][B] of the CWA). The municipal NPDES stormwater permit requires each municipality to demonstrate that it has the authority to control spills and prevent the discharge of contaminants to the MS4. NPDES stormwater permits are designed to reduce the discharge of pollutants carried by stormwater to the maximum extent practicable through the use of best management practices (BMPs) and other provisions appropriate for the control of stormwater pollutants.States, counties, cities, and towns have the responsibility and duty to protect the municipal storm-drain system against pollutants and contaminants from entering. Municipalities have or are in the process of developing their authority to control stormwater pollution and contaminants from entering these systems.Another portion of the 1972 CWA (Section 303[d]) deals with total maximum daily load (TMDL). TMDL is a plan that identifies all the sources of pollution to a given stretch of river or waterway and then allocates, through numeric limits, the loading of each pollutant to make sure the water-quality standards of that stretch of river, waterway, or coastal area are not violated. The TMDL concept is a holistic approach to watershed pollution and will focus regulators on all pollution sources and their cumulative effects on resources instead of smaller individual problems and developments.With all this said, the burden lies with state and local governments to implement stormwater control programs to satisfy the NPDES stormwater permit requirements and the TMDL program. There are many generic and proprietary stormwater BMPs available that can be used on new development, infill development, and retrofit development to satisfy the NPDES stormwater requirements.What I have seen is an unequal treatment of generic BMPs and proprietary BMPs. Generic BMPs favored by regulators are given a “carte blanche” approval even when there is no or minimal long-term testing and monitoring of their effectiveness. As examples, the new “state-of-the-art” 2000 Maryland Stormwater Design Manual gives full approval to use generic underground sand filters, pocket sand filters, bioretention, and infiltration basins as acceptable BMPs, meeting Maryland’s 80% total suspended solids (TSS) removal criteria and the 40% phosphorous removal criteria. However, the number of monitored BMPs for this group is zero (pages 2-37 to 2-39 and Appendix D-5 of the 2000 Maryland Stormwater Design Manual). These generic practices have received blanket approval to be used as meeting the new stormwater criteria. In addition, nine generic practices do not meet the 80% TSS removal criteria based on monitoring data (Appendix D-5). The approved Maryland BMP practices that do not meet the criteria are the micropool, wet pond, wet extended detention pond, multiple pond, extended detention wetland, pond/wetland, pocket wetland, perimeter sand filter, and wet swale. Why are all of these generic BMPs approved for use to satisfy the established criteria when the documentation indicates that these practices fall short of meeting those criteria? Should these practices be placed in an unapproved category until adequate monitoring data have demonstrated that they meet the established criteria?In contrast, many proprietary BMPs have had numerous and long-term independent monitoring studies conducted, but these studies are generally not accepted by Maryland regulators and others. The proprietary systems are not included on the accepted BMP list and are not allowed to be used as stand-alone devices on new development projects. Maryland regulators require long-term monitoring studies to be conducted in the state and to show that all of the established criteria are met before a proprietary BMP device is approved. Proprietary products have as many, if not more, studies as those cited in the 2000 Maryland Stormwater Design Manual for generic BMPs. Where is the fairness in this evaluation system?Many of the studies for generic and proprietary stormwater devices are short-term monitoring studies, which do not give a true assessment of the long-term average effectiveness. Long-term studies are needed for all types of systems to evaluate their long-term ability to remove pollutants. In the absence of long-term and large numbers of studies, an equal playing-field criterion is needed to evaluate both generic and proprietary types of stormwater BMPs. A major gap in the BMP approval process is the limited consideration given to the operation and maintenance of BMPs. As we all know, maintenance of stormwater BMPs is a sore subject in many jurisdictions. Generic devices generally go many years without maintenance and quickly lose their effectiveness, and their average removal rates are much lower than the studies would indicate. In contrast, most proprietary devices need regular maintenance (generally yearly) to maintain peak effectiveness. Regular maintenance will result in higher average, long-term effectiveness, but the organizations and regulators writing the criteria do not consider this fact. Is this a fair system?The new Maryland manual also leaves a major gap in the “urban hotspot” criteria. Most of us would think that a major highway, a gas station, or a commercial site should be designated as a hotspot, but the manual fails to recognize this fact. These land uses can meet the new stormwater criteria by infiltrating a portion of the site’s runoff. Is this the kind of criteria we need to protect deep groundwater and shallow groundwater resources that feed our rivers and streams? I think not.“Smart Growth” and similar land conservation initiatives emphasize concentrated high-density development, infill development, and redevelopment of existing towns, cities, and urban centers. Why are we spending so much effort on stormwater criteria that are focused on low-density sprawl development? The new Maryland stormwater manual is 2 in. thick and accompanied by a lengthy new stormwater regulation. However, infill development and redevelopment are given only a few sentences in the new manual and regulation. Is this a Smart Growth measure, or will this new stormwater management system help further urban sprawl and create greater losses of valuable ranches and farmland?Another area of concern is that, although national and state initiatives are in place to encourage innovative stormwater management technologies that are economically and environmentally sustainable, these efforts are being thwarted by government regulators. There seems to be a number of institutional and regulatory impediments to the development and use of innovative urban stormwater management control technologies, especially proprietary BMPs.The mission is the protection and restoration of our natural resources. We need all the available tools to reach this desired end result. We should not be setting unequal and unfair criteria that are biased in their evaluation of generic BMPs over proprietary BMP devices. Instead we should be evaluating BMP effectiveness with long-term operational issues and maintenance in mind. Urban areas have a large number of hotspots, and we need to evaluate the criteria very carefully or we could cause a bigger, long-term problem for our surface and groundwater resources. New stormwater manuals should focus on the rehabilitation of urban centers and not on traditional sprawl development. We should be encouraging new and innovative urban BMPs that can restore the stormwater runoff problems of the past. We must utilize every opportunity and BMP system to reduce and clean up nonpoint-source runoff from all existing and new land uses. It seems to me that we still have a long way to go until we develop the true “state-of-the-art” stormwater design manual and regulation.

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