Information: Reference to specific commercial products, processes, or services by trade name, trademark, service mark, manufacturer, or otherwise does not constitute or imply endorsement, recommendation, or favoring by the Minnesota Pollution Control Agency.

Up-Flo Filter w/Filter Ribbons is is an advanced stormwater treatment system that combines sedimentation and screening with filtration. It is classified as a manufactured treatment device (mtd).

This page provides information on pollutant removal credits for Up-Flo Filter w/Filter Ribbons, links to supporting information, and links to information on system design, inspection, operation, and maintenance.

TP and TSS credits

When conditions described in this section are met, applicable Up-Flo Filter w/Filter Ribbons systems are approved for the following removals for total suspended solids (TSS) and total phosphorus (TP).

  • TSS: 80 percent removal
  • TP: Tier 1
    • Credit: 50 percent removal
    • Conditions for receiving credit
      • Inspect manufactured treatment device a minimum of twice during year 1. Conduct inspections following manufacturer’s instructions/recommendations and any additional instructions listed in this section. Use maintenance indicators provided by manufacturers to determine if maintenance is needed. Maintenance procedures should follow manufacturer’s guidelines. After year 1, follow manufacturers inspection, operation, and maintenance schedule and procedures unless otherwise required or unless year 1 inspections indicate a need for increased inspection and/or operation and maintenance.
      • Comply with appropriate configurations and Use conditions
  • TP: Tier 2 - no Tier 2 credit at this time
  • TP: Tier 3 - no Tier 3 credit at this time

For more information on credits, see TP and TSS credits and guidance for manufactured treatment devices (mtds)


Not applicable

Use conditions

To receive the full credit, Up-Flo Filter w/Filter Ribbons systems must comply with the following conditions.

  1. Design, assemble, install, operate, and maintain Up-Flo Filter w/Filter Ribbons systems in accordance with applicable manuals.
  2. Sized at a hydraulic loading rate of no greater than 15 gallons per minute (gpm) per filter module or 0.8 gpm per sq. ft. of filter ribbon surface area.
  3. Systems are designed to treat a specified water quality volume or annual average runoff volume. The annual average runoff treated can be determined using methods that are specified here.
  4. Each site plan must undergo Up-Flo Filter w/Filter Ribbons review before approval of the unit for site installation.
  5. Follow maintenance procedures given in the most recent version of the Up-Flo Filter w/Filter Ribbons Operation and Maintenance Manual.
  6. Discharges from the Up-Flo Filter w/Filter Ribbons units shall not cause or contribute to water quality standards violations in receiving waters.
  7. When applicable, adhere to use conditions provided in Washington State Department of Ecology's report (Ecology's Conditions of Use) GENERAL USE LEVEL DESIGNATION FOR BASIC (TSS) AND PHOSPHORUS TREATMENT For Hydro International, Inc. Up-Flo® Filter Using Filter Ribbons. Note that some information in this report is specific to Washington State and not applicable to Minnesota.

Data analysis

Credits apply only to the water being treated by a device. The applicable treatment volume must be determined using one of the methods described here.

The Tier 1 credit equals the TAPE-approved credits. Tier 2 and Tier 3 credits were determined by analyzing water quality data collected at a system tested at the Lake Union Ship Canal Test Facility in Seattle, WA required servicing after 4 months or 12.7% of a water year. The site consisted of transportation land use with 22.7 acres of impervious draining to the device. The device was 18.7 ft2.

MPCA compiled data from TAPE Technical Evaluation Report generated for the site. Below are summary statistics for the device.

  • Median TP inflow - 0.109 mg/L
  • Median TP removal (all data) - 50.3%
  • 95% lower confidence limit TP removal (all data) - 31%
  • Median TP removal (data meeting TAPE criteria) - 57.1%
  • 95% lower confidence limit TP removal (data meeting TAPE criteria) - 49.9%
  • Median TSS removal (all data) - 75%
  • 95% lower confidence limit TSS removal (all data) - 59.9%

TAPE means and medians represent values meeting TAPE criteria for TP (inflow concentrations of 0.1 to 0.5 mg/L) and TSS (inflow concentrations greater than 20 mg/L). Of the 20 samples, TAPE medians and means represent 13 samples for TP.

The 95% boot strap TP-removal LCL for TAPE-analyzed data was 49.9%. The LCL for all data was 19.1%, but there appeared to be multiple outliers in the dataset. The TAPE approval document noted the small median particle size (11 microns) in runoff to the device, citing multiple times when the device became clogged and required maintenance: "The system was subjected to atypical sediment loading and needed to be serviced after 4 months, or 12.7% of a water year. Monitoring personnel observed similar sediment loading and blinding issues with other systems evaluated at the Test Facility. The runoff from the Test Facility is not expected to be characteristic of other urban runoff applications". We therefore recommend using the TAPE LCL of 50% for Tier 1 TP credit.

No Tier 2 or Tier 3 credit is given for this device based on data collected for TAPE certification.

TSS credit is the TAPE default of 80% since the LCL was less than 80%

The median particle size for the tested device was 11 microns, which likely accounts for the relatively poor performance compared to other mtds.

To link to the Excel spreadsheet containing water monitoring data click here

Inspection, operation, and maintenance

Meet the conditions specified for the appropriate TP and/or TSS credit.

Meet the following conditions, unless conditions for the appropriate TP and/or TSS credit are more stringent.

  • 2 maintenance visits required annually if annual precipitation exceeds 30 inches; one visit annually if annual precipitation is less than 30 inches
  • Spring visit to remove salts and sands and fall visit for sediment and leaves
  • Maintenance includes removing trash, degraded mulch, and accumulated debris from the filter surface and replacing the mulch layer


This page was last edited on 16 February 2023, at 15:30.