If any group of engineers was asked to list which organization(s) they reference for industry standards, I would expect ASTM International to be frequently cited. Founded in 1898, ASTM has maintained incredible name recognition—and for good reason. It’s a leading organization in the development and delivery of voluntary consensus standards.

Under the ASTM process, standards are created, developed and established voluntarily based on an agreed-upon need for the standardization of test methods or materials. The entire process—from conception to publication—requires consensus. In my opinion, it’s from this voluntary consensus that ASTM’s reputation is earned; it’s difficult to argue against a standard that has been agreed upon by a committee of industry professionals. But what does this have to do with stormwater? Thanks to the recent creation of ASTM Committee E64 on Stormwater Control Measures, I can now say: quite a lot!

Stormwater BMPs

There are two main types of best management practices (BMPs) for the control and treatment of stormwater: non-structural and structural. Non-structural BMPs generally encompass programmatic approaches that focus on the prevention or reduction of stormwater generation and pollution.

Common prevention-type BMPs include the protection and conservation of riparian areas and natural flow paths, minimization of the total disturbed area in construction, revegetation of disturbed areas with native species, pollution source control with street sweeping, reduction of new and existing impervious coverage, and decentralization of stormwater management.

Structural BMPs, on the other hand, are constructed devices designed to manage the stormwater generated by land development. These types of BMPs typically target the prevention or reduction of discharged pollutants and/or runoff volume by employing infiltration, detention, retention, particulate settling or filtration (bit.ly/3IV8RAa). These structural practices are commonly referred to as stormwater control measures (SCMs).

A New Committee

As innovation in stormwater management has led to a dramatic increase in the types of SCMs available to planners and engineers, the need for standardization to provide consistency to the performance evaluation and verification process for the various SCMs has never been greater. To address this need, ASTM Committee E64 was formed in 2020 to create standards under the following scope:

The promotion of knowledge of the family of technologies known internationally as stormwater control measures (SCMs), including stimulation of research and the development of test methods, specifications, practices, guides, and nomenclature. SCMs provide for stormwater quality treatment; volume control; flow management; and runoff detention, retention and capture and use.

Design criteria and regulations for SCMs vary widely from state to state (and even city to city), usually to account for the nuances of the local regulatory priorities, geology, weather and pollutants of concern. So how can a set of standards developed for an international audience be useful, and what good can it do for the industry that current design criteria and regulations don’t already achieve?

I believe the answer lies in ensuring robust performance data are collected in a manner that allows for geographic transferability of performance data and providing comparability among different SCMs. When it comes to the verification of an SCM’s performance for the reduction of pollutants such as total suspended solids, nutrients and metals, it’s critical that test data are collected under consistent conditions and reported with consistent and complete metrics so comparison of results is possible.

Evaluating MTDs

This is a lesson well learned when it comes to the verification of performance for manufactured treatment devices (MTDs). The nation’s leading MTD performance evaluation programs, New Jersey Department of Environmental Protection (NJDEP) and the Washington State Department of Ecology TAPE (Technology Assessment Protocol – Ecology), have evolved during the last two decades to become the premier verification programs for SCM evaluation in the lab and field, respectively.

Both NJDEP and Washington State Department of Ecology administer robust performance-verification programs designed around local treatment goals, but whose certification and verification reports are relied on by many jurisdictions across the country. However, some state and local stormwater programs have been reluctant to adopt these state-level programs and have expressed an interest in a national standard. As there is already an industry consensus on the value these two programs bring to the standardization of performance evaluation methods, they have become the building blocks of several of the first standards created by ASTM Committee E64.

Setting the Standard

While the aforementioned programs currently are used predominantly by manufacturers to prove their innovative solutions can meet regulatory requirements, they also can be utilized for the evaluation of non-proprietary SCMs. Regardless of the type of system tested, following the NJDEP or TAPE protocols provides an unmatched level of comparability between performance data gathered within each of the respective programs. Such comparability allows engineers and regulators to easily evaluate whether an SCM meets their treatment needs without requiring the inhouse expertise to thoroughly assess and compare the results.

Ideally, all SCMs would be tested in such a standardized manner so engineers and regulators can pinpoint the impact that changes in design might have on the overall SCM performance via comparison of research. Innovation thrives in an environment of clearly defined procedures and requirements, neither of which are ubiquitously available for non-proprietary SCMs. These are precisely the type of benefits that incorporating the existing NJDEP and TAPE protocols into ASTM standards should bring to the stormwater industry.

A reading of the International Stormwater BMP Database 2020 Summary Statistics report by the Water Research Foundation profoundly illustrates the need for standardization of SCM evaluation. The report is an impressive feat of data analysis that identifies trends in SCM performance for the removal of common stormwater pollutants and highlights gaps where additional research is needed.

The performance data collected by the BMP Database doesn’t follow a singular test method or evaluation protocol, which results in the need for significant data screening and statistical analysis to produce the summary report. Although the national standardization of test methods won’t eliminate the need for data screening and statistical analysis, improved comparability would help make these types of analyses easier and more accessible. With more accessible data comes better design guidance for SCMs. Ultimately, the national standardization of SCM evaluation offers a bright future of innovation, a better understanding of SCM performance and cleaner water.