Sustainable Land Development Today - November/December 2008 - (Page 32)

STORMWATER The Conundrum Over AULs Are some stormwater management BMPs for brownfield redevelopment truly the best solutions? By Donald W. Richardson, C.P.G., R.B.P. Stormwatermanagement has always been a challenging aspect of brownfield redevelopment. One of the most common methods of facilitating a cost-effective yet risk-based cleanup — Activity and Use Limitation (AUL) property restrictions — poses a particular challenge to stormwater quality and quantity. The EPA estimates that 90 percent of brownfield-redevelopment projects across the country use some form of AUL property restriction to comply with risk and regulatory requirements. In fact, federal, state and local governments have pushed for legislation, developed policy and embraced the use of AULs in lieu of requiring unrestricted site cleanups in non-residential end-use exposure risk scenarios. Many of these AULs involve construction of an impermeable cap or engineering control (e.g. parking areas, roads, buildings, etc) designed to cover low level contamination. However, while AUL controls can effectively manage a potential environmental and human exposure pathway, some pose adverse impacts on stormwater quantity and quality. These effects are not consistent with the intent of new stormwater regulations or to achieving voluntary, sustainable site redevelopment goals outlined by the United States Green Building Council’s (USGBC) Leadership in Energy and Environmental Design (LEED®) guidelines. turn, states certify that their approach to stormwater management meets or exceeds the practices developed by the EPA. For example, a manufacturing facility in New Jersey is required to maintain a New Jersey Pollutant Discharge Elimination System (NJPDES) permit to monitor stormwater quality from an asphalt parking draining to a catch basin connected to a storm-sewer system. The asphalt parking area serves to cap some residual, low-level soil contamination. The permit holder is required to monitor Total Suspended Solids (TSS) semi-annually during select storm events. To maintain compliance with the low-level TSS threshold values, the permitee must perform monthly sweeping of the parking lot to remove sediment and other particles that might elevate TSS values above the permit threshold. The AUL-engineered control cap in this case overrides the ability to implement BMPs that would remove the need for a NJPDES permit. A BMP design to either direct stormwater runoff to an onsite infiltration gallery or a green-design swale could be done instead, if regulators would integrate these two methods. The Conundrum AULs are frequently used to protect on-site workers and the public from exposure to contaminants that exist or remain on a brownfield redevelopment property. They often consist of engineering controls that might include impermeable caps over soil contamination, fencing to prevent access, slurry walls to control groundwater flow, groundwater, pump-and-treat systems to treat and/or control groundwater and other physical controls. One of the more popular engineered controls is to use impervious caps to create a barrier to potential soil or vapor exposure scenarios from existing contamination. These two types of AULs work best if they are applied together. For example, a parking lot in combination with a new building foundation may be used to cap a contaminated site and a deed notice or declaration of environmental restriction is placed in the title documents to alert future owners of sitecap maintenance requirements. The EPA dictates stormwater best management practices (BMPs) through the National Pollutant Discharge Elimination System (NPDES) program. In Toward Greener Brownfields Now, add in green-business drivers or sustainable-site-development practices. In a competitive real estate market with high energy costs, brownfield developers are seeking to differentiate themselves in the marketplace by meeting LEED-scoring incentives to keep stormwater on-site. These incentives include the use of green infrastructure management approaches and technologies to infiltrate, evapotranspire, capture and reuse stormwater to maintain or restore natural hydrologies. Sealcoat cover during placement of chip material. The use of AULs allow restricted-use developments, such as brownfields, to proceed in a cost-effective manner, while still addressing the potential human and environmental exposure risks posed by residual contamination left on a site. As long as a comprehensive long-term management plan is put in place to maintain the contamination controls, these nonpermanent AUL remedies are effective. 32 November/December 2008 Sustainable Land Development Today

Table of Contents Feed for the Digital Edition of Sustainable Land Development Today - November/December 2008

Sustainable Land Development Today - November/December 2008 Contents Our Voice Editorial Board SLDT Resources The BottomLine Go Forth and Tread Lightly on the Land It’s About Name Recognition Managing Risk in the Sustainable Building Frontier Industry Spotlight Achieving Sustainable Land Development Worthy of Recognition Stormwater Wastewater Erosion Control Innovation Classifieds Advertiser Index Last Word

Sustainable Land Development Today - November/December 2008

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