Sunday, May 14, 2023

Treatment in BMP’s and LID’s for InfoSWMM and ICM SWMM - with Emojis

 Treatment in BMP’s and LID’s

5.1 Treatment

Excerpt from the EPA manual Storm Water Management Model Reference Manual Volume III – Water Quality (PDF) which can be found here

5.1.1 Background

Stormwater Quality Management: BMPs and LID 💧🌿

Stormwater quality is pivotal for urban and environmental health. It's primarily managed through a blend of "best management practices" (BMPs) and a hydrologic source control technique, widely recognized as "low impact development" (LID). The treatment can be at the runoff source or within the conveyance network. While LID's source treatment will be discussed later, this section sheds light on SWMM's modeling of treatment within the conveyance system.

Unit Treatment Processes in Conveyance Systems 🌀: Table 5-1, inspired by Huber et al. (2006), classifies the treatment processes leveraged by various BMPs within conveyance systems. The aspiration is to model these processes fundamentally, correlating pollutant removal with design parameters, hydraulic variables, and chemical properties. However, the current understanding often limits this approach, pushing reliance towards empirical data-driven relationships.

Challenges with Monitoring Data 📊: Strecker et al. (2001) highlight the intricacies of using monitoring data to draw consistent BMP effectiveness conclusions. The International Stormwater BMP Database ( emerges as a robust resource, offering BMP performance data from 500+ studies across 17 BMP and LID categories. This database is a living entity, continually updated with fresh data.

BMP Performance Overview 🌱: Table 5-2 showcases the median influent and effluent event mean concentrations (EMCs) across various BMP categories and pollutants, as extracted from the BMP database. The yellow-highlighted cells signify significant pollutant removal by the respective BMP category. Meanwhile, Table 5-3 provides a snapshot of median removal percentages of common pollutants by filtration, ponds, and wetlands, as documented in the Minnesota Stormwater Manual. These percentages align with the median EMC figures from Table 5-2.

In Summary 📝: 

Stormwater quality management, through BMPs and LID, is vital. While comprehensive modeling remains a challenge, resources like the BMP Database offer invaluable empirical insights. Leveraging this data can aid in enhancing stormwater treatment, safeguarding both urban landscapes and natural ecosystems. 🌍💧🌳.ntages are consistent with those inferred from median EMC numbers in the BMP database table 5-2.

Table 5-1 Treatment processes used by various types of BMPs

ProcessDefinitionExample BMPs
SedimentationGravitational settling of suspended particles from the water column.Ponds, wetlands, vaults, and tanks.
FlotationSeparation of particulates with a specific gravity less than water (e.g., trash, oil and grease).Oil-water separators, density separators, dissolved-air flotation.
FiltrationRemoval of particulates by passing water through a porous medium like sand, gravel, soil, etc.Sand filters, screens, and bar racks.
InfiltrationAllowing captured runoff to infiltrate into the ground reducing both runoff volume and loadings of particulates and dissolved nutrients and heavy metals.Infiltration basins, ponds, and constructed wetlands.
AdsorptionBinding of contaminants to clay particles, vegetation or certain filter media.Infiltration systems, sand filters with iron oxide, constructed wetlands.
Biological Uptake and ConversionUptake of nutrients by aquatic plants and microorganisms; conversion of organics to less harmful compounds by bacteria and other organisms.Ponds and wetlands.
Chemical TreatmentChemicals used to promote settling and filtration. Disinfectants used to treat combined sewer overflows.Ponds, wetlands, rapid mixing devices.
Natural Degradation (volatilization, hydrolysis, photolysis)Chemical decomposition or conversion to a gaseous state by natural processes.Ponds and wetlands.
Hydrodynamic SeparationUses the physics of flowing water to create a swirling vortex to remove both settleable particulates and floatables.Swirl concentrators, secondary current devices, oil-water separators.

Table 5-2 Median inlet and outlet EMCs for selected stormwater treatment practices

PollutantMedia FiltrationDetention BasinRetention PondWetland BasinManufactured Device
TSS mg/L52.78.766.824.270.713.520.49.0634.518.4
F. Coliform, #/100mL135054214801030192070713000614022102750
Cadmium, ug/L0.310.160.390.310.490.230.310.180.400.28
Chromium, ug/L2.  3.662.82
Copper, ug/L11.286.0110.625.679.574.995.613.5713.4210.16
Lead, ug/L10.51.696.083.108.482.762.
Nickel, ug/L3.512.205.643.354.462.19  3.844.51
Zinc, ug/L77.317.970.017.953.621.
Total P, mg/L0.
Orthophosphate, mg/L0.050.030.530.390.
Total N, mg/L1.060.821.402.371.831.
TKN, mg/L0.960.571.491.611.281.050.951.011.591.48
NOX, mg/L0.330.510.550.360.430.

Source: International Stormwater BMP Database, “International Stormwater Best Management Practices (BMP) Database Pollutant Category Summary Statistical Addendum: TSS, Bacteria, Nutrients, and Metals”, July 2012 (

Table 5-3 Median pollutant removal percentages for select stormwater BMPs

PollutantSand FilterPondsWetlands
Total Suspended Solids858473
Total Phosphorus775038
Particulate Phosphorus919169
Dissolved Phosphorus6000
Total Nitrogen353030
Zinc and Copper507070

Source: Minnesota Stormwater Manual (

No comments:

AI Rivers of Wisdom about ICM SWMM

Here's the text "Rivers of Wisdom" formatted with one sentence per line: [Verse 1] 🌊 Beneath the ancient oak, where shadows p...