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Filtration Manufactured Treatment Devices (view source)
Revision as of 00:15, 7 February 2024
, 9 months ago→Sizing
As with OGS, the Rational Method can be employed to estimate flow rates discharged to the MTD for the site in question based on historical rainfall records and the selected recording interval (≤1 hour, 15 minute preferred where available). These flow rates are in turn used to calculate hydraulic and sediment mass loading to the selected Filtration MTD model (TRCA, 2023)<ref>TRCA. 2023. Guidance on the Use and Application of Results from
As with OGS, the Rational Method can be employed to estimate flow rates discharged to the MTD for the site in question based on historical rainfall records and the selected recording interval (≤1 hour, 15 minute preferred where available). These flow rates are in turn used to calculate hydraulic and sediment mass loading to the selected Filtration MTD model (TRCA, 2023)<ref>TRCA. 2023. Guidance on the Use and Application of Results from
Verified Laboratory and Field Testing for Stormwater Manufactured Treatment Devices. A Publicly Available Specification Prepared by: Toronto and Region Conservation Authority and Supported by: The Standards Council of Canada. June, 2023. Accessed: https://sustainabletechnologies.ca/app/uploads/2023/07/SETV-Guidance-PAS-2023-07-27-English.pdf</ref>. In general, sizing should ensure that at least 90% of the annual runoff volume during an average year is treated (i.e. does not exceed the system treatment flow rate as defined in Table 2 below).
Verified Laboratory and Field Testing for Stormwater Manufactured Treatment Devices. A Publicly Available Specification Prepared by: Toronto and Region Conservation Authority and Supported by: The Standards Council of Canada. June, 2023. Accessed: https://sustainabletechnologies.ca/app/uploads/2023/07/SETV-Guidance-PAS-2023-07-27-English.pdf</ref>. In general, sizing should ensure that at least 90% of the annual runoff volume during an average year is treated (i.e. does not exceed the system treatment flow rate as defined in Table 2 below).
{|class="wikitable" style="width: 1100px;"
|+ Key System Design Parameters
|-
!style="width: 30%;"|Design Parameter
!style="width: 70%;"|Description
|-
|'''System treatment flow rate'''
|The treatment flow rate represents the maximum flow rate that was conveyed through the treatment chamber during field testing without bypassing. The system bypass rate is greater than the system treatment flow rate. When the system treatment flow rate is expressed per unit sedimentation area, it is referred to as the system treatment surface loading rate.
|-
|'''Maximum filtration flux rate or media infiltration rate'''
|The maximum filtration flux rate is a measure of the maximum treatment flow rate per unit filter surface area. For devices with membrane or media cartridges the rate is provided both per cartridge and for the total filtration surface area (multiple cartridges). For devices with media filters where flows are conveyed vertically from top to bottom the rate is expressed as an infiltration rate for the system. In both instances, the maximum filtration flux rate is determined from field testing as the lowest measured treatment flow rate prior to the onset of bypass, which would typically occur just before required filter maintenance.
|-
|'''Detention time'''
|The detention time is the time required for water to be conveyed through the MTD at a given flow rate. It is influenced by the wet volume, or maximum volume in the MTD at a specified flow rate.
|-
|'''Design total suspended solids (TSS) runoff concentration'''
|The suspended solids concentration in site runoff that is used to calculate sediment mass loading to the unit over the course of an average precipitation year.
|-
|'''Maintenance sediment storage depth and volume'''
|The maintenance sediment storage depth/volume represents the storage depth/volume available for sedimentation either on top of the media filter or within the chamber housing the filter cartridges and pretreatment chamber(s) (if applicable), as recommended by the manufacturer and confirmed through field testing. The sump depth is constant across different unit sizes, but the sump volume increases in relation to the effective filtration area, as per the scaling rule noted above.
|-}<br>
</br>
The recommended maintenance frequency must adhere to the findings in the field test report or be shown through detailed design calculations to meet the approval agency maintenance interval requirements, with a buffer of safety added for uncertainties in site specific sediment, gross solids and debris loads. MTD inspections may need to be more frequent at sites where the site runoff quality is likely to lead to faster clogging of system filtration components than was observed in the field test. Some runoff quality parameters that may enhance [[clogging]] potential relative to the field test results may include the presence of a larger mass of finer particles (silts and clays), higher organic matter content or hydrocarbon loading, and higher bacterial loads, which can enhance the development of biofilms.
==References==
==References==