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===Links=== | ===Links=== | ||
+ | *[[MPCA Simple Estimator]] | ||
+ | *[[Case study for using the MPCA Simple Estimator to meet TMDL permit requirements]] | ||
+ | *[[Guidance and examples for using the MPCA Estimator]] | ||
+ | *[[Quick Guide: MPCA Estimator tab]] | ||
+ | *[[Forms, guidance, and resources for completing the TMDL annual report form]] |
This page provides a list of considerations when using models to meet MS4 (Municipal Separate Storm Sewer System) total maximum daily load permit requirements. For detailed guidance or additional information, see the links section for each model.
The Minimal Impact Design Standards calculator is a moderately simple tool for estimating pollutant load reductions associated with best management practices (BMPs).
The MIDS calculator has a Site informationtab for site information and a Schematics'' tab for inputting information for individual BMPs.
The Results tab displays summary information for the site and for each BMP.
The following table summarizes a QAQC list for interpreting results.
General MIDS Calculator result QAQC list
Link to this table
QAQC / Review Item | Related MIDS Calculator Output |
---|---|
Review device routing | Review routing in "Schematic" window |
Confirm area routed to individual BMPs is correct | BMP Properties --> Watershed |
Confirm total watershed area is correct | Review "Site Information" window |
Confirm annual precipitation total is correct | Review zip code in "Site Information" window |
Review watershed pollutant concentrations | Compare watershed areal loading to literature values |
Review TSS/TP removal rates | Compare pollutant removal values to literature values |
Confirm no routing between non-volume reduction BMPs | Removal estimates for non-volume reduction BMPs in series are incorrect. For this reason, routing between non-volume reduction BMPs should be disconnected |
Review BMP sizing recommendations and review contributing watershed area | Bypass from undersized BMPs is not calculated for non-volume reduction BMPs. For this reason, only the area for which the BMP is correctly-sized should be modeled to the BMP (the remainder should be modeled as untreated) |
The MPCA Simple Estimator is a spreadsheet-based tool used to predict watershed-based loading for total phosphorus (TP) and total suspended solids (TSS), and estimate pollutant removal at water quality best management practices (BMPs).
The spreadsheet consists of 10 worksheets, one for each sub-watershed. Data from these worksheets is compiled on an eleventh worksheet called "Summary sheet". This summary sheet shows results for each sub-watershed and cumulative for the project/study.
Quality assurance/quality control procedures are summarized in the following table.
General MPCA Simple Estimator result QAQC list
Link to this table
QAQC / Review item | Related MIDS Calculator Output |
---|---|
Confirm total watershed area is correct | Review land use-based area assigned in the "total load" table |
Confirm annual precipitation totals are correct | Review annual rainfall values in column G and confirm all are the same value |
Review watershed pollutant concentrations | Compare watershed areal loading values in the "total load" table to literature values in Table 9 |
Review watershed routing to BMPs | Review land use-based area assigned to each BMP type |
Confirm only the directly-contributing watershed area is applied for each BMP | The area assigned to a given BMP should be only the directly-contributing watershed area and should NOT include area tributary to other BMPs upstream |
Review TSS/TP removal rates | Compare pollutant removal values to literature values. Note: percent load reduction shown for each BMP type is calculated based on the total watershed loading |
Review BMP sizing recommendations and review contributing watershed area | Bypass from undersized BMPs is not calculated. For this reason, only the area for which the BMP is correctly-sized should be modeled to the BMP (the remainder should be modeled as untreated). |