Test page mtds Revision as of 18:52, 10 December 2020 by Mtrojan (talk | contribs) (Created page with "Guidance for MTD crediting Manufactured treatment devices (mtds) remove pollutants from stormwater runoff. This page provides pollutant removal credits for mtds and inclu...")
Manufactured treatment devices (mtds) remove pollutants from stormwater runoff. This page provides pollutant removal credits for mtds and includes guidance on determining credits for mtds.
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What manufactured treatment devices are credited?
Only Washington State Technology Assessment Protocol - Ecology (TAPE) devices that received General Use Level Designation (GULD) are credited for pollutant reductions. TAPE-approved devices include devices that are considered pretreatment devices in Minnesota, as well as permanent structural practices not designed specifically for pretreatment. In Minnesota, pretreatment is required for permanent treatment practices and therefore pretreatment devices are not credited for pollutant removal.
Pollutant removal credits are provided for the following devices.
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| Device name | Manufacturer | TAPE approval date | Total suspended solids | Total phosphorus |
|---|---|---|---|---|
| BayFilter w/EMC Media | BaySaver Technologies, Inc. | 7/10/19 | Basic | Basic |
| BioPod Biofilter with Curb Inlet | Oldcastle Infrastructure, Inc. | 10/28/19 | Basic | Basic |
| Compost-Amended Biofiltration Swale | WSDOT | 8/26/13 | Basic | |
| ecoStorm plus | Watertectonics, Inc. | 1/9/13 | Basic | |
| Filterra Bioscape | CONTECH Engineered Solutions, LLC. | 9/16/19 Basic | Basic | |
| Filterra System | CONTECH Engineered Solutions, LLC. | 6/11/20 | Tiered | Tiered |
| FloGard Perk Filter | Oldcastle Infrastructure, Inc. | 8/9/18 | Basic | Basic |
| Media Filter Drain | WSDOT | 5/22/14 | Basic | Basic |
| Media Filtration System | CONTECH Engineered Solutions, LLC. | 11/15/16 | Basic | |
| MWS-Linear Modular Wetland | Bio Clean Environmental Services, Inc. (A Forterra Company) | 12/16/19 | Basic | Basic |
| StormFilter using PhosphoSorb Media | CONTECH Engineered Solutions, LLC. | 1/2/20 | Basic | Basic |
| Stormfilter using ZPG Media | CONTECH Engineered Solutions, LLC. | 4/14/17 | Basic | |
| StormGarden Modular Stormwater Bio-filtration System | Environmental Solutions | 8/28/19 | Basic | Basic |
| The Kraken | Bio Clean Environmental Services, Inc. (A Forterra Company) | 12/16/19 | Basic | Basic |
| Up-Flo Filter w/Filter Ribbons Hydro International | 3/5/19 | Basic | Basic |
Credit documentation
Each of the above devices has a supporting document that explains the credits and conditions necessary to receive the credit. Some devices have multiple credit tiers, that is they receive a basic credit or a higher credit if certain conditions are met. The above table indicates which practices have tiered credits. The individual supporting documents contain specific information about the device. This information should be carefully read and understood before assigning the appropriate credit to a device.
Credit levels
If conditions described in individual support documents are met, all devices receive base credits for total suspended solids (TSS) and total phosphorus (TP). These are TAPE-approved values as summarized below.
- TSS – 80% removal for the annual volume treated by the device
- TP – 50% removal for the annual volume treated by the device
MPCA analyzed available data from testing done for Washington State. Some devices may receive higher credit if conditions in support documents are met. Derivation of these credits is provided in the support documents.
Calculating annual volume treated by a device
Devices tested and approved in Washington State are required to treat 91% or more of the average annual runoff. Because climatic conditions differ between Washington State and Minnesota, the annual average volume to which the credit applies must be determined. The following are acceptable methods for calculating the average annual volume treated by a device.
- Translators
- Modeling
- Monitoring
- Devices approved in similar climatic conditions
- The device is downstream of a retention device that ensures a specified volume is treated by the device
Credit support documents
Although specific guidance and methods for crediting are provided on individual device support documents, an overview of information in these documents is provided here. All devices must meet the following conditions for credit.
- The device must be designed, assembled, installed, operated, and maintained following manufacturers specifications.
- All systems must meet specified