Standardization News

According to the U.S. Environmental Protection Agency (EPA), stormwater is defined as “rainwater or melted snow that runs off streets, lawns, and other sites.” But it is the next step in the process – when that runoff is absorbed back into the ground and eventually finds its way into aquifers, streams, and rivers – where problems can appear.

That’s because stormwater is largely unregulated and can contain a wide range of pollutants including metals, chemical waste, PFAS (i.e., “forever” chemicals), and more, depending on the area being drained.

“There is a lot of variability depending on the land use and the basin that is draining the site being tested,” says Carla Milesi, vice chair of ASTM International’s committee on stormwater control measures (E64). “A lot of the testing that is being done is using highway runoff, which can be pretty polluted. But worse, it is ‘gunky’ and it clogs the testing systems up pretty quickly. You might go to a site that’s in a more commercial setting and the runoff might contain larger particles that are not as quick to clog up the systems, but there are higher levels of total suspended solids. Stormwater conditions can really be all over the place.”

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The stormwater control industry exists to help monitor and manage the discharge of these untreated waters, including the installation of stormwater control measures to treat stormwater and reduce pollutant concentrations in runoff. Now this work is going national, as a result of the recent creation of The National Center for Stormwater Testing and Evaluation for Products and Practices (STEPP), a non-profit alliance of state and regional groups. The initiative is aimed at developing testing and verification standards for use across the stormwater sector. Spurred by this news, E64 recently published the standard practice for collecting storm based paired influent and effluent flow weighted composite water samples using automated samplers (E3400) in order to assess the pollutant removal abilities of various stormwater control measures.

“Many people in our industry look to ASTM standards to ensure that things are being done well,” Milesi says. “So we wanted to anchor the new STEPP protocols in a standard that can be used to direct sample collection. But we also wanted it to be broad enough that it could be used by anyone who is looking to collect this kind of data, whether it's a manufacturer that wants to collect a few samples on the performance of their technology or researchers at a university who want to see how well a swale is doing.”

A swale is a grassy depression that controls stormwater velocity and infiltrates runoff where feasible. They are a stormwater treatment technique often used along highways and roads that experience heavy runoff.

Under new standard, collected sample data can be used to assess the ability of stormwater control measures (SCMs) to remove pollutants from stormwater runoff and whether or not they are effective in their intended purpose. The standard itself provides a specific practice for using automated samplers to collect paired, flow-weighted influent and effluent stormwater composite samples from stormwater-control measures.

Flow-weighted automated samplers eliminate the need for staff to be out in the field during storms to collect samples and are connected to flow-monitoring devices linked to the stormwater treatment technology being tested. E3400 outlines the considerations that go into the placement of these flow meters; where samplers are installed; how the sampler needs to be calibrated to collect flow weight samples; and more. Following these guidelines and with properly collected samples in hand, stormwater researchers, SCM manufacturers, and others can then more accurately assess the pollutant-removal abilities of these products and practices and how effective they are in practice.

“Aside from the value in learning about runoff in general, just looking at the influent side of things can really help us better understand what sorts of pollutant levels we see coming off of different kinds of land uses and different basins,” says Milesi. “That information can be used to determine where you would want to install stormwater treatment, for instance. If you tend to have a lot higher pollutants coming off of a certain sized roadway or a certain sized parking lot, it can help direct you to where you can get the biggest bang for your buck when doing some kind of stormwater treatment.”

Tim Sprinkle is a freelance writer based in Colorado Springs, CO. He has written for Yahoo, The Street, and other websites.