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#Discharges from the Filterra units shall not cause or contribute to water quality standards violations in receiving waters. === | #Discharges from the Filterra units shall not cause or contribute to water quality standards violations in receiving waters. === | ||
− | == | + | ===Data analysis=== |
− | + | Credits apply only to the water being treated by a device. The applicable treatment volume must be determined using one of the [https://stormwater.pca.state.mn.us/index.php?title=Test_page_mtds#Calculating_annual_volume_treated_by_a_device methods described here]. | |
− | 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. | + | 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. |
[[File:Filterra data summary.png|400px|thumb|alt=excel screen shot|<font size=3>Summary statistics for Filterra monitoring, Bellingham, WA. Click on image to enlarge.</font size>]] | [[File:Filterra data summary.png|400px|thumb|alt=excel screen shot|<font size=3>Summary statistics for Filterra monitoring, Bellingham, WA. Click on image to enlarge.</font size>]] | ||
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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 | + | 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 recommended Tier 2 value is 65%. |
+ | |||
+ | 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]. | ||
To link to the Excel spreadsheet containing water monitoring data click here - [[File:Water quality data for MTDs Feb 4.xlsx]] | To link to the Excel spreadsheet containing water monitoring data click here - [[File:Water quality data for MTDs Feb 4.xlsx]] | ||
+ | |||
+ | ===Inspection, operation, and maintenance=== | ||
+ | *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 | ||
==Links== | ==Links== |
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.
When conditions described in this section are met, applicable Contech Filterra systems are approved for the following pollutant removals.
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%. The recommended Tier 2 value is 65%.
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