New Stormwater Treatment Methods

New stormwater treatment methods are being researched and developed every year. It is important that South Portland's stormwater approach keep pace with new technologies, and that only those technologies which have been thoroughly tested for their effectiveness are accepted. The best, most cost-effective way to accomplish these goals of flexibility and quality assurance is for South Portland to look to an existing, independent certification program which conducts testing of new stormwater technologies.

Among the few certification programs out there, we selected the Washington State Dept. of Ecology Technology Assessment Protocol – Ecology (TAPE) certification, because it has a relatively large number of systems in the research pipeline, its data and methods are available online, and it is funded at the time of writing. Specifically, we recommend for Basic and Post-Construction SW Management Plans all systems certified by TAPE "general use" (GULD) for "Enhanced" (metals) or "Phosphorus" pollutant types. We do NOT recommend including "pilot use" or "conditional use" systems, because they are as yet unproven.

For more information on TAPE, including the current list of GULD enhanced and phosphorus pollutant types, see:

At the time of writing, the following systems were approved by WA-TAPE:

  • Americast filterra® system (GULD – Enhanced)
  • WSDOT Media Filter Drain (GULD – Enhanced and Phosphorus)
  • Kristar FloGard Perk Filter® (GULD – Phosphorus)

Basic Features

Some of these methods are manufactured and shipped to a site for a relatively "off-the-shelf" approach, with manufacturers providing technical assistance in siting and sizing their products.

Site Suitability

Refer to information on each specific system. See either the WA TAPE link above, or individual manufacturer's specifications.


These systems all require some level of maintenance, which may include protecting them from sedimentation on an ongoing basis, replacement of vegetation and/or soil media if clogged or after a number of years, among other tasks.