Center Design

The STTC was designed to investigate:

• Pollutant removal effectiveness of stormwater treatment technologies.
• The maintenance requirements and life-cycle costs of stormwater treatment technologies.

The STTC is located in a 1,000 acre watershed that includes a mix of highway and residential land use. Water collected throughout this watershed ultimately flows into a 7-foot diameter pipe running parallel to I205 in Portland, OR. At the STTC, stormwater from this pipe can be diverted to one of three Test Bays using either air-controlled pumps or via gravity flow. Monitoring performed at the STTC indicates this stormwater contains representative concentrations of common pollutants (e.g., suspended sediment, nutrients, heavy metals, oil) in urban stormwater runoff along with other gross solids and leaves).

Using this source of stormwater, the STTC was designed to allow the pollutant removal effectiveness of stormwater treatment technologies to be assessed in accordance with the nationally recognized Technology Assessment Protocol – Ecology (TAPE) program. The TAPE program was developed by the Washington Department of Ecology (Ecology) to certify the performance of emerging stormwater treatment technologies prior to allowing their widespread use in Washington State. Pursuant to this protocol, samples are collected to characterize pollutant concentrations in stormwater before and after treatment by the technology. The data obtained from these samples are subsequently used to quantify the pollutant removal effectiveness of the technology following procedures developed for the TAPE program.

At the STTC, samples can be collected over a user defined hydrograph that is accurately delivered to a technology using a Programmable Logic Controller (PLC) and recorded by a Supervisory Control and Data Acquisition (SCADA) system. This provides more control over the testing process compared to a typical field site; reducing the time and costs required to perform this testing and producing more reliable data on system performance.

Following certification that a stormwater treatment technology can meet pollutant removal effectiveness targets defined by Ecology for the TAPE program, the maintenance requirements and life-cycle costs of the technology can also be evaluated. For this evaluation, stormwater will be delivered to the technology at its maximum flow capacity during repeated storm events; the goal will be to “artificially age” the technology to determine its maintenance requirements on a relatively short timeframe. This process will continue until the system becomes too clogged with sediment to function as designed – the point of failure. The mass of sediment that entered the technology and caused this failure will be measured. Maintenance techniques, materials, and costs required to keep the technology effective up to the point of failure and then fully recharged will also be tracked. Using these data, the life-cycle costs to operate the technology will then be estimated and reported.