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Line 48: − + + − Stormwater Management Criteria for the site include: − Quantity Control – meet Humber River Unit Release Rates; − Quality Control – 80% TSS Removal; − Water Balance – Best Efforts to match post to pre; − Erosion control, 25mm erosion storm released over 72 hours, on-site retention of the first 5mm of rainfall − Stormwater Management Strategy − A series of sub-surface infiltration chambers providing on-site retention/infiltration of the 5mm storm, water balance to reduce runoff volumes, and storage of the 100-year storm; − Quality treatment provided using an oil/grit separator immediately upstream of each of the infiltration chambers, filtration through the infiltration chamber, and finally a stormwater management facility provided prior to discharging from the site. − Final erosion control provided within the stormwater management facility, controlling release rates to maintain the existing condition erosion exceedance values. − Final design required both LIDs to reduce the overall runoff volumes, but also sub-surface storage chambers to provide quantity control for rare storm events up to the 100-year design storm. Due to large area required for truck parking, limited opportunities for more landscaping to promote evapotranspiration, runoff volumes increased beyond ability of LIDs to negate the need for quantity control. − + + + + + + + + + + + + + − + − + − + − + − + − + − + − + − + − + − The site is located in Toronto. The size of the site is 0.53 ha. The site currently developed as commercial and residential. Proposed high rise (11-storeys) residential building with 3 levels of underground parking Proposed average site imperviousness is 90% (excluding uncontrolled buffer area 0.22 ha)+ − + − + − + − + + + + +
→Literature Review
==Literature Review==
==Literature Review==
Review examples of where LID practices with quantity control components have been used for achieving flood control
Review examples of where LID practices with quantity control components have been used for achieving flood control
Example 1: Costco Distribution Centre
<h3>Example 1: Costco Distribution Centre</h3>
Costco Distribution Centre located within Block 59, Vaughan. The site has 26.4 ha and the land use is commercial site with an average site imperviousness of approximately 90%;
Costco Distribution Centre located within Block 59, Vaughan. The site has 26.4 ha and the land use is commercial site with an average site imperviousness of approximately 90%;
Example 2. West Gormley, Town of Richmond Hill
'''Stormwater Management Criteria'''
*Quantity Control – meet Humber River Unit Release Rates;
*Quality Control – 80% TSS Removal;
*Water Balance – Best Efforts to match post to pre;
*Erosion control, 25mm erosion storm released over 72 hours, on-site retention of the first 5mm of rainfall
'''Stormwater Management Strategy'''
#A series of sub-surface infiltration chambers providing on-site retention/infiltration of the 5mm storm, water balance to reduce runoff volumes, and storage of the 100-year storm;
#Quality treatment provided using an oil/grit separator immediately upstream of each of the infiltration chambers, filtration through the infiltration chamber, and finally a stormwater management facility provided prior to discharging from the site.
#Final erosion control provided within the stormwater management facility, controlling release rates to maintain the existing condition erosion exceedance values.
*Final design required both LIDs to reduce the overall runoff volumes, but also sub-surface storage chambers to provide quantity control for rare storm events up to the *100-year design storm. Due to large area required for truck parking, limited opportunities for more landscaping to promote evapotranspiration, runoff volumes increased beyond ability of LIDs to negate the need for quantity control.
<h3>Example 2. West Gormley, Town of Richmond Hill</h3>
Residential development consisting of low and medium density land-use is implemented on the site. Average site imperviousness is approximately 60%;
Residential development consisting of low and medium density land-use is implemented on the site. Average site imperviousness is approximately 60%;
Stormwater Management Criteria for the site include:
Quantity Control – Rouge River – match post development peak flow rates to pre-development;
'''Stormwater Management Criteria'''
Quality Control – 80% TSS Removal;
*Quantity Control – Rouge River – match post development peak flow rates to pre-development;
Water Balance –Match post development water budget to pre-development;
*Quality Control – 80% TSS Removal;
Erosion Control – Southern portion of site discharging to a natural dry valley feature. Feature and contributing drainage area consists of very sandy soil, producing no runoff until a greater than 25-year storm event.
*Water Balance –Match post development water budget to pre-development;
Therefore, development discharging to dry valley needed to match runoff volumes, or have no runoff from development area for storms less than 25-year design storm.
*Erosion Control – Southern portion of site discharging to a natural dry valley feature. Feature and contributing drainage area consists of very sandy soil, producing no runoff until a greater than 25-year storm event.
Stormwater Management Strategy
:Therefore, development discharging to dry valley needed to match runoff volumes, or have no runoff from development area for storms less than 25-year design storm.
Use a combination of increased topsoil depths, perforated storm sewers, stormwater management facility, and an infiltration facility to provide quality, quantity, and reduce runoff volumes to match pre-development.
Even with favorable soils and maximum use of infiltration techniques, site still requires quantity control storage for large storm events.
'''Stormwater Management Strategy'''
Example 3: 3775-4005 Dundas St West (includes 2-6 Humber Hill Ave), Toronto
*Use a combination of increased topsoil depths, perforated storm sewers, stormwater management facility, and an infiltration facility to provide quality, quantity, and reduce runoff volumes to match pre-development.
*Even with favorable soils and maximum use of infiltration techniques, site still requires quantity control storage for large storm events.
Stormwater Management Criteria
Quantity Control – not requirement as drains to Lower Humber River
<h3>Example 3: 3775-4005 Dundas St West (includes 2-6 Humber Hill Ave), Toronto</h3>
Quality Control – 80% TSS Removal
The size of the site is 0.53 ha. The site currently developed as commercial and residential. Proposed high rise (11-storeys) residential building with 3 levels of underground parking Proposed average site imperviousness is 90% (excluding uncontrolled buffer area 0.22 ha)
Water balance/Erosion Control – Retention of 5 mm event on-site
'''Stormwater Management Criteria'''
*Quantity Control – not requirement as drains to Lower Humber River
*Quality Control – 80% TSS Removal
*Water balance/Erosion Control – Retention of 5 mm event on-site
==Stormwater Strategy==
==Stormwater Strategy==