Those within the industry are tackling vague standards and inconsistent performance measures

By David R. Miley

Recently an EPA official referred to stormwater treatment as the last environmental frontier. As pioneers, companies that manufacture and sell stormwater treatment systems are wrestling–right along with customers–with the challenges of vague regulatory requirements, imperfect product testing protocols and performance standards, and the commercial viability of exciting new technologies.

To tackle some of the pioneering aspects of our industry, developers and manufacturers of stormwater treatment technology have been meeting at the Water Environment Federation’s annual conference and exhibition (WEFTEC) for the past three years. As the industry lacks a conference truly specific to stormwater, WEFTEC–most recently held in Anaheim, CA, in October 2000–has emerged as the most relevant venue for manufacturers of stormwater treatment solutions to discuss challenges facing manufacturers and customers alike, from product testing protocols to performance standards. These meetings have solidified an ad hoc group committed to ongoing discussion and resolution of industrywide challenges, demonstrating that stormwater treatment is quickly emerging as a significant, viable industry. As we move forward, this representative group might well form the foundation of a new industry association. This article represents the first of several periodic articles that representatives of this group hope to publish in Stormwater in an effort to keep our customers informed of what we feel are key issues and considerations in understanding and evaluating stormwater treatment technologies. (See the sidebar for a list of participating companies.)

Manufactured best management practices (BMPs) for stormwater are a relatively recent addition to the long-time standard treatment for runoff from roadways, parking lots, and industrial sites. Ponds and bioswales are the de facto standard, one that most regulators accept as effective. As development pressures on land in urban and suburban areas mount, developers, engineers, and regulators are looking beyond ponds for solutions that are reliable, effective, and affordable in treating both the quantity and quality of stormwater runoff.

BMPs offer significant advantages over land-based systems in most circumstances. They can be implemented with far less land than a pond requires. They are flow rate—based and more effective at spill containment, and in general they pose lower public-health and safety risks. Manufactured systems are by definition produced under controlled conditions, and therefore quality is significantly more consistent than with the site-constructed, land-based systems. This consistency helps to ensure stormwater quality of a much more predictable standard.

The problem most specifiers face in evaluating manufactured BMPs is that regulations are underdeveloped and sometimes even ambiguous. In addition, because there is no industrywide standard, engineers have to rely on each manufacturer’s individualized product performance data. Benchmarking products and solutions between manufacturers can therefore be difficult. Many companies are making significant progress in field and lab testing, however, which is providing data and facilitating more appropriate product selection.

A variety of manufactured BMPs are currently available, specially designed to address contaminants associated with stormwater pollution. These products include hydrodynamic separators, filter technology, and catch-basin inserts. Hydrodynamic separators are effective for removing sediment, debris, and free-floating oil (currently the three areas of greatest concern). Filter technology is a growing market sector and comprises a variety of systems that target organic constituents and heavy metals. Catch-basin inserts, traditionally provided by companies servicing regional markets and ideally suited for retrofits, form a product group that is growing in sophistication and application.

Developing standardized testing protocols and documenting product performance have emerged as top priorities for continued collaboration among industry leaders. The ultimate goal is to help differentiate unique product strengths to help regulators and specifiers employ the most appropriate, effective solutions based on the special demands of their sites.

So far a number of independent, nonindustry testing programs have been conducted on a regional basis, but none has yielded any significant progress. While we support these efforts, the general consensus of the group in Anaheim was that the industry should be taking a more active role in the development of testing protocols and performance standards that will be used to govern our industry’s products. The development of these standards is a complicated proposition with many challenges–challenges more easily met through a collaborative effort between our industry and the regulators and academics working on the standards. Proof of our industry’s commitment to testing and performance verification are the dozens of third-party, independent field studies of manufactured BMPs implemented at sites around the country. In general, each of these tests offers valuable feedback and information. We believe, however, that the reliability of the data would be enhanced by implementing a "monitoring agreement" between the evaluation team and the manufacturer that would ensure a high level of communication between the manufacturer and evaluator, mutually agreed upon testing protocols, and review of the data before dissemination.

The currently prevailing water-quality standard for the industry and manufactured BMPs is 80% total suspended solids (TSS) on a net annual basis. Though widely used, its applicability across the board as a one-size-fits-all standard is debatable. This standard was originally adopted for manufactured BMPs for two primary reasons. First, it represents a level of treatment generally attributed to properly designed wetlands and other traditional land-based systems. Second, TSS removal data provide a good surrogate measurement for estimating the removal of other priority pollutants.

On a practical level, site-specific conditions vary widely in the field and can have a significant impact on actual system performance. Site conditions, such as seasonal loss of vegetation, ice formation, biological activity, poor design, and contractor error, all have a major impact on land-based system performance. Other site factors, such as a predominance of fine or colloidal solids, dissolved metals and nutrients, and the presence of unusual materials (from horse manure and coal dust to iron precipitate), also might not be adequately addressed using the 80% TSS standard. The current standard, however flawed, does provide a target for efforts to restore and maintain the health of our rivers, streams, coastal areas, and groundwater. While the bar might be too high or the standard too broad, it has encouraged manufacturers to set their sights high and to invest in research and development (R&D) programs and testing programs to try to meet these standards.

At the same time we must, as an industry, focus on developing a standard that addresses the shortcomings of current standards, taking into account the latest research and generally accepted goals. Clearly, there are a host of situations where these broad guidelines might not be appropriate or at least not the most beneficial. For instance, if stormwater runoff has an annual average concentration of less than 100 mg/lit., should we still be concerned with removing the full 80% of that load? What if a water body is particularly sensitive to siltation or to a specific metal or nutrient or bacteria? A recent development is the total maximum daily load (TMDL), which is being implemented in some priority watersheds. TMDLs require detailed analysis of a watershed to assess its capacity to accept various pollutant loads. Portions of the total acceptable load are then allocated to different sources within the watershed. Although TMDLs are an attractive approach, the difficulty and expense of developing them begs the question of their universal applicability.

Much research will need to be undertaken to determine the current and future impact of pollutants on water quality, the extent to which they should be removed, and the standards for measuring such removal. Promulgation of appropriate stormwater treatment guidelines is contingent on our understanding of site-specific conditions. The growth in deployment of manufactured BMPs also provides an opportunity to ensure that all treatment systems are adequately maintained, thereby providing another safeguard to water quality. Many in the stormwater industry encourage regulators to write mandatory maintenance requirements into regulation for manufactured and land-based BMPs.

Establishing performance guidelines to universally address the issue of pollutant removal will undoubtedly be the subject of many long and serious discussions across the industry. It will clearly test our knowledge and challenge our R&D capabilities–not to mention our resolve. But with the collective goal of watershed protection in mind, the industry must move forward to explore these challenges, providing site-specific stormwater solutions while conforming to the existing broad regulation. This ad hoc group has offered a good way to start addressing these issues. We hope that as we move forward we will gain input and involvement from other companies interested in contributing to industrywide guidelines.

In an upcoming issue of Stormwater, this ad hoc industry group will be offering continued discussion around some of the specific issues surrounding performance testing and verification. Like our customers–regulators, engineers, and contractors–we know that reliable, independent testing is critical to accomplishing the ultimate goal of any stormwater solution: maintaining the health and purity of natural watershed environments.

David R. Miley is president of Vortechnics Inc. in Portland, ME. This article was derived from discussions by a collaboration of stormwater companies who met at WEFTEC 2000.