Sustainable Land Development Today - November/December 2008 - (Page 33)

The bottom line is that developers must look for innovative reuses for this water. For instance, to earn a stormwatermanagement credit, the LEED guidelines require the owner/developer to implement and sustain a stormwater management plan that infiltrates, collects and reuses runoff or evapotranpirates runoff from at least 15 percent of the precipitation falling on the entire project site both for an average-weather year and a twoyear, 24-hour design storm. The suggested strategies for achieving the credit include water reuse through landscape irrigation, toilet and urinal flushing, and custodial purposes. The majority of strategies (e.g. surface-to-groundwater infiltration, bioswale and green filter buffers) used to meet on-site stormwater-management LEED credits cannot easily be implemented if AULs are present on a site. Implementing engineering controls will significantly reduce options for BMP design of sustainable, stormwater-management strategies. Another LEED credit can be earned by increasing on-site infiltration, reducing or eliminating pollution from stormwater runoff and eliminating contaminants. In this case, the owner would have to ensure that: a) existing site imperviousness is less than or equal to 50 percent or b) greater than 50 percent and then must reduce volume by 25 percent using the two-year, 24-hour design storm. The quality-control LEED credit requires the owner to implement a stormwater management plan with BMPs that treats and captures 90 percent of average annual rainfall and reduce 80 percent of the post-development average annual TSS. Unfortunately, the existing infrastructure on a brownfield site is not designed to support the amount of stormwater that is generated in many cases. Best Runoff Strategies There are a number of best practices that owners and developers can put in place on every project to address the issue. First, anticipate the potential desire to achieve LEED building and site certification early in the brownfield-redevelopment process. Anyone involved in the process of selecting BMPs to manage stormwater should consider a wide variety of factors, including pollutant-removal potential, stormwater-volume reduction, installation considerations (soils, slopes, and climate and rainfall patterns), capital costs, maintenance costs, and similar factors. Second, attempt to incorporate brownfield-cleanup strategies with stormwater BMPs by demonstrating risks and rewards to regulators early in the process. For example, try to avoid conventional, impermeable-cap engineering controls over soil contamination. Also, attempt to better characterize the nature and extent of the soil contamination and seek ways to facilitate stormwater infiltration onsite. Finally, develop and implement comprehensive operation and maintenance plans for the sustainable, stormwaterdrainage system. The pubic must have confidence first and foremost in the adequacy of the engineered controls. Even partial reduction (say by 25 percent) of stormwater runoff through sustainable BMPs is a significant step in the right direction. Clearly, more research is needed to develop stormwater-management practices on brownfield sites. Organizations such as the Interstate Technical and Regulatory Commission (ITRC) are in a unique position to advance this research and develop approaches that meet regulatory requirements. ITRC is currently entertaining a proposal to initiate the research with the objective of developing sustainable solutions to this challenge. SLDT About the author: Donald W. Richardson, C.P.G., R.B.P., is a senior program manager with Kleinfelder’s Brownfields Practice Group. He can be reached at DRichardson@kleinfelder.com. The implications and risks are greater when failed erosion-control structures such as this are designed to encapsulate underlying soil contamination. Balancing Act There is no one answer to the problem at this time. Finding a balanced solution to brownfield redevelopment that takes into account LEED criteria and stormwa- ter regulations often requires the engineering teams to think outside the box. For example, Kleinfelder, a nationwide engineering and project-management firm, used a series of BMPs to turn a hazardous wasteland in Yuma, Ariz., into a recreational site by successfully implementing a green solution to brownfield remediation. The 24-acre recreational site had lead concentrations exceeding non-residential, soil-lead limits by 45 percent. The dynamics of excavation included a $200,000 funding limit. The selected remedial alternative needed to address potential lead-exposure pathways for the future use of the site as an archery range. Kleinfelder engineers borrowed from road construction technologies utilized by the Arizona Department of Transportation to design a chipseal cap to cover lead-impacted soils. In addition, to satisfy Flood Control District requirements, the team completed stormwaterrunoff calculations resulting in design of two retention basins and riprap flood control. By using this design, the team avoided taking the contaminated soil offsite to landfills that would release gases into the air and allowed for the reuse of the land. Furthermore, this plan involved utilizing county personnel to perform the field work, which realized significant cost savings. www.SLDTonline.com 33 http://www.SLDTonline.com

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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