How Ecology Evaluates Emerging Stormwater Treatment Technologies

Testing Protocols (TAPE & CTAPE)

Ecology has developed a new technology evaluation program (see Chapter 12 of Volume V of the western Washington stormwater manual). The program reviews engineering reports on the performance of new technologies and reports the results at Ecology's web site. Test protocols have been developed for permanent stormwater treatment systems and for construction sites. These protocols specify sampling criteria, site and technology information, quality assurance and quality control measures, target pollutants, and evaluation report content.

Technology Assessment Protocol (TAPE) – Ecology's TAPE is intended for ultra-urban treatment technologies and those treatment technologies that do not have a chemical component for treatment.

Chemical Technology Assessment Protocol (CTAPE) – Ecology's CTAPE is intended for construction site treatment technologies and any technology that uses a chemical component for treatment.


Pretreatment is generally applied to:

Intended to achieve 50% removal of fine (50 micron-mean size) and 80% removal of coarse (125-micron-mean size) total suspended solids for influent concentrations greater than 100 mg/L, but less than 200 mg/L. For influent concentrations less than 100 mg/L, the facilities are intended to achieve effluent goals of 50 mg/L of fine and 20 mg/L of coarse total suspended solids.

Oil Treatment

Intended to achieve the goals of no ongoing or recurring visible sheen and a daily average total petroleum hydrocarbon concentration no greater than 10 mg/L with a maximum of 15 mg/L for discrete (grab) samples.

Basic Treatment

Intended to achieve a goal of 80% removal of total suspended solids for an influent concentration range of 100mg/L to 200 mg/L.

For influent concentration less than 100mg/L the effluent goal is 20mg/L total suspended solids.

For influent concentrations greater than 200mg/L a higher treatment goal is intended. Technologies listed in this section with a GULD designation are also approved for Pre-treatment in accordance with Volume V Section 6.2 of the Stormwater Management Manual for Western Washington (SWMMWW)and Section 5.2.1 of the Stormwater Management Manual for Eastern Washington (SWMMEW).

Enhanced Treatment

Intended to achieve a higher level of treatment than basic treatment. Enhanced treatment is targeted at removing dissolved metals.

Phosphorous Treatment

Intended to achieve a goal of 50% total phosphorus removal for an influent concentration range of 0.1 to 0.5 mg/L as well as achieving basic treatment.

Construction Site

Construction treatment is intended to achieve the goals of a maximum of 5 NTUs above background (background of 50 NTUs or less), not more than 10% increase in turbidity where background is greater than 50 NTUs, pH of 6.5-8.5 in freshwater and 7.0-8.5 in marine water, and no visible oil sheen.

Ecology's use level designation's are as follows:

GULD - General Use Level Designation

General Use Level Designation (GULD) technologies may be used in Washington state, subject to use level designation conditions.

CULD - Conditional Use Level Designation

Conditional Use Level Designation (CULD) allows continued use of the technology for a specified time period during which field testing must be completed by the vendor and/or developer. Not all CULD technologies are required to conduct field testing. Units that are in place do not have to be removed after the specified time period. Use is subject to the use level designation conditions.

PULD - Pilot Level Use Designation

Pilot Use Level Designation (PULD) allows limited use of the technology to allow field testing to be conducted. PULD technologies may be installed provided that the vendor and/or developer agree to conduct field testing based on the TAPE at all installations.

Please note: Government entities covered by a municipal stormwater NPDES permit must notify Ecology when a PULD technology is proposed (form is available in TAPE guidance document).

Board of External Reviewers (BER)

To help Ecology with new technology evaluations for permanent systems and for chemical treatment at construction sites, a Board of External Reviewers (BER) was formed providing national expertise in stormwater treatment technologies. They act in a direct review capacity to provide recommendations to Ecology on the level of development of each technology. BER members will be paid for their time. Each application to TAPE and C-TAPE will be assigned a minimum of three members from the BER to provide detailed review and comment on the applications, Quality Assurance Project Plans (QAPPs), and Technical Evaluation Reports (TERs).

Levels of Development

Ecology and the TRC are currently reviewing several performance evaluation reports on new stormwater treatment technologies. These reports will be used to determine "levels of development" of each of the new technologies.