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MPCA compiled data from Appendix K of the report TECHNICAL EVALUATION REPORT - FILTERRA SYSTEM PHOSPHORUS TREATMENT AND SUPPLEMENTAL BASIC TREATMENT PERFORMANCE MONITORING. Summary statistics are shown in the adjacent image. 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). Thus, of the 22 samples, TAPE medians and means represent 10 samples for TP and 18 samples for TSS, while the remaining data in the figure are for all 22 events. | MPCA compiled data from Appendix K of the report TECHNICAL EVALUATION REPORT - FILTERRA SYSTEM PHOSPHORUS TREATMENT AND SUPPLEMENTAL BASIC TREATMENT PERFORMANCE MONITORING. Summary statistics are shown in the adjacent image. 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). Thus, of the 22 samples, TAPE medians and means represent 10 samples for TP and 18 samples for TSS, while the remaining data in the figure are for all 22 events. | ||
− | The 95% boot strap LCL is 52% for all data and 69% for TAPE analyzed data. TP removal decreases as the inflow concentration decreases below 0.1. However, if we consider only TP values > 0.05 mg/L, the LCL is 58.9 percent. TP concentrations of 0.05 mg/L or less are uncommon in Minnesota. Consequently, the recommended Tier 2 value is 58%. The median removal for all data was 67% and for TAPE-analyzed data was 78.5%. | + | The 95% boot strap LCL is 52% for all data and 69% for TAPE analyzed data. TP removal decreases as the inflow concentration decreases below 0.1. However, if we consider only TP values > 0.05 mg/L, the LCL is 58.9 percent. TP concentrations of 0.05 mg/L or less are uncommon in Minnesota. Consequently, the recommended Tier 2 value is 58%. The median removal for all data was 67% and for TAPE-analyzed data was 78.5%. We therefore recommend a Tier 3 value of 60%, which is conservative but meets a commonly employed regulatory threshold. |
Phosphorus removal, as a percent of influent TP, decreased as influent TP concentration decreased below 0.1 mg/L and as the ratio of Dissolved P:TP increased. For a discussion of effects of these factors on crediting, [https://stormwater.pca.state.mn.us/index.php?title=TP_and_TSS_credits_and_guidance_for_manufactured_treatment_devices_(mtds)#Derivation_of_credits link here]. | Phosphorus removal, as a percent of influent TP, decreased as influent TP concentration decreased below 0.1 mg/L and as the ratio of Dissolved P:TP increased. For a discussion of effects of these factors on crediting, [https://stormwater.pca.state.mn.us/index.php?title=TP_and_TSS_credits_and_guidance_for_manufactured_treatment_devices_(mtds)#Derivation_of_credits link here]. |
Contech's Filterra is an engineered bioretention system designed to filter pollutants from stormwater runoff. This page provides information on pollutant removal credits for Filterra, links to supporting information, and links to information on system design, inspection, operation, and maintenance.
When conditions described in this section are met, applicable Contech Filterra systems are approved for the following removals for total suspended solids (TSS) and total phosphorus (TP).
For more information on credits, see TP and TSS credits and guidance for manufactured treatment devices (mtds)
Applicable configurations (systems) include
To receive the full credit, Filterra systems must comply with the following conditions.
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 Bellingham, Washington. The site consisted of residential land use with 0.4 acres of impervious draining to the device. The device was 4 ft by 6.5 ft, with a filter media depth of 1.8 feet and a ponding depth of 0.75 feet.
MPCA compiled data from Appendix K of the report TECHNICAL EVALUATION REPORT - FILTERRA SYSTEM PHOSPHORUS TREATMENT AND SUPPLEMENTAL BASIC TREATMENT PERFORMANCE MONITORING. Summary statistics are shown in the adjacent image. 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). Thus, of the 22 samples, TAPE medians and means represent 10 samples for TP and 18 samples for TSS, while the remaining data in the figure are for all 22 events.
The 95% boot strap LCL is 52% for all data and 69% for TAPE analyzed data. TP removal decreases as the inflow concentration decreases below 0.1. However, if we consider only TP values > 0.05 mg/L, the LCL is 58.9 percent. TP concentrations of 0.05 mg/L or less are uncommon in Minnesota. Consequently, the recommended Tier 2 value is 58%. The median removal for all data was 67% and for TAPE-analyzed data was 78.5%. We therefore recommend a Tier 3 value of 60%, which is conservative but meets a commonly employed regulatory threshold.
Phosphorus removal, as a percent of influent TP, decreased as influent TP concentration decreased below 0.1 mg/L and as the ratio of Dissolved P:TP increased. For a discussion of effects of these factors on crediting, link here.
To link to the Excel spreadsheet containing water monitoring data click here - File:Water quality data for MTDs Feb 4.xlsx