music simulates the operation of the following different typesof stormwater quality improvement facilities:
Buffer Strips are commonly used as asource control measure, particularly for management of road runoff.They are effective in the removal of coarse to medium-sizesediments and can be used as an effective pre-treatment measure forbioretention systems. They also can assist in reduction ofpeak flows for smaller events and may promote infiltrationdependent upon the underlying soil conditions.
Vegetated Swales are open channelsystems which use vegetation to aid the removal of sediment andsuspended solids. These systems are subjected to fairly highhydraulic loading and the removal efficiency is dependent on thedensity and height of the vegetation in the channel. As forbuffer strips, the vegetation can assist in reducing peak flows fora range of events (dependent on the swale width and length) and mayalso be beneficial in volumetric reduction through infiltration,dependent upon the underlying soil conditions.
Wetlands are an effective stormwatertreatment measure for the removal of fine suspended solids andassociated contaminants, as well as soluble contaminants. They can also provide significant storage for a range of stormevents. These systems use a combination of physical, chemicaland biological processes to remove stormwater pollutants. They arecommonly used as end-of-pipe stormwater treatment systems, butrecent research has shown that they are scalable for application asnear-source control measures. The model also has the capability tomodel the reuse of treated stormwater stored in wetlandsystems.
BioretentionSystems (also known as biofiltration systemsor rain-gardens) promote the removal of particulate and solublecontaminants by passing stormwater water through a filter medium,either for infiltration into surrounding soils, or for collectionby an underdrain. This category is thus also used for modellingvegetated infiltration systems, whilst unvegetated infiltrationsystems are modelled with the Infiltration node (see below). Welldesigned bioretention systems can provide both flow management andwater quality benefits. A range of factors affect the treatmentperformance of the bioretention systems, including the type andcomposition of filter media (e.g. loamy sand), the presence andtype of vegetation used, and the presence of design enhancementssuch as the use of a saturated zone to enhance denitrification. Inmusic, the prediction of bioretention system performance is basedon extensive research undertaken by the Facility for AdvancingWater Biofiltration (see www.monash.edu.au/fawb). It is strongly recommendedthat FAWBs Stormwater Biofiltration Adoption Guidelines beconsulted when designing (and modelling) bioretentionsystems.
InfiltrationSystems reduce the volume of stormwater, andhence the frequency of runoff and the mass of contaminants carried,by infiltration into the bed of the basin. In music theInfiltration node is used only to simulatethe performance of unvegetated infiltrationsystems (e.g.using gravel or sand filter media). Vegetatedinfiltration systems should be modelled using the Bioretentionnode (seeabove). Ingeneral, the use of vegetated infiltration systems is advocatedwherever possible. In unvegetated systems, coarse particulates aredeposited on the floor of the basin. Dissolved material and veryfine particulates infiltrate into the soil, hence the potential forcontamination of groundwater needs to be addressed. Inflows inexcess of the storage and infiltration capacity of the basin willoverflow and continue downstream. By reducing the volume of surfacerunoff, infiltration systems help to counteract the increase inrunoff volume and frequency that generally accompaniesurbanisation.
Media Filtration Systemsare commonly modular or pre-fabricated systems which are used forfiltering stormwater. These systems typically use a simple sandmedia, or a more specialised engineered media, and may bespecifically tailored to provide water quality suitable forstormwater harvesting. You can edit the properties of this node tomatch the specifications of the filtration system being used (suchmodification should be undertaken only using published andpeer-reviewed data).
Ponds are stormwatertreatment measures such as open water bodies (without significantshallow vegetated areas in the predominant flow paths) andornamental ponds. The treatment of stormwater is predominantlyassociated with temporary detention to reduce peak flows andfacilitate settling of suspended solids. Other treatment processespromoted in pond systems include phytoplankton assimilation ofsoluble nutrients and ultra-violet disinfection. These processesare currently not explicitly included in the modelling algorithm.The model also has the capability to model the reuse of treatedstormwater stored in ponds.
Rainwater Tanks enable reuse ofroof runoff for in-house or garden use. While some settling mayoccur in the tank, the main contaminant removal process is thediversion of impervious area runoff to pervious areas (via gardenuse) or to sewer (after in-house use). Effective use of rainwatertanks can reduce the directly connected impervious area of acatchment, and help to counteract the increase in impervious areathat generally accompanies urbanisation through reduction in runoffvolumes.
Sedimentation Basinsare open water bodies aimed predominantly at the removal of coarseand medium particles. Typically they operate at high hydraulicloading rates, and have fairly short detention times. The treatmentof stormwater in sedimentation basins is achieved almost entirelyby temporary detention to facilitate settling of suspended solids.No other biological or biochemical processes are simulated withinthe Sedimentation Basin node.
DetentionBasins areopen or closed storages aimed primarily at reducing downstream peakflows although they also offer some removal of coarse and mediumparticles. Typically they operate at high hydraulic loading rates,and have fairly short detention times. The treatment of stormwaterin detention basins is achieved almost entirely by temporarydetention to facilitate settling of suspended solids. No otherbiological or biochemical processes are simulated within theDetention Basin node.
Gross Pollutant Traps aredevices for effective removal of solids conveyed by stormwaterwhich are typically larger than 5 mm. Often, they are used as thefirst treatment element in a stormwater treatment train. There aremany proprietary gross pollutant traps currently suitable for usein urban catchments and information on their performance isbecoming available. As for media filtration systems, information onperformance of these systems should only be sourced from publishedand peer-reviewed data.
Generic Treatment Nodesallw you to define transfer functions for flows and water qualityfor stormwater quality treatment measures which are not explicitlymodelled in music. Generic nodes can also be used to model suchsituations as flow diversion, flow dilution, contamination by seweroverflow, etc.