Q-2, r. 9.01 - Design code of a storm water management system eligible for a declaration of compliance

Section 30 Disposition versions

2020-12-31

30. The parameters of the computer model must comply with the values of the attributes indicated in Table 3.8 for “General options” type elements.

For the other parameters of the computer model, the values of the attributes, other than the Horton or Green-Ampt attributes, must be determined following a calibration of the model or, failing that, comply with the values indicated in Table 3.8.

For the values of the Horton or Green-Ampt attributes, if onsite data are available, the date must be used or, failing that, the values indicated in Table 3.8 must be complied with.

Table 3.8 Parameters of the SWMM5 computer model

Element of the model	Attribute	Value
General options	Units	L/s or m3/s
General options	Routing model	Dynamic wave
General options	Infiltration model	Horton or de Green-Ampt
General options	Reporting time steps	≤ 1 minute
General options	Routing time steps	≤ 30 seconds
General options	Allow ponding	Activated
Subcatchments	Roughness coefficient (N) – impervious area	Table 3.5
Subcatchments	Roughness coefficient (N) – pervious area
Subcatchments	Depth of depression storage - impervious area	Table 3.9
Subcatchments	Depth of depression storage - pervious area
Subcatchments	Horton – maximum infiltration rate (fo)	Table 3.10
Subcatchments	Horton – minimum infiltration rate (fc)	Table 3.11
Subcatchments	Horton – decay constant (k)	≥ 2
Subcatchments	Green-Ampt – Suction head at the wetting front	Table 3.12
Subcatchments	Green-Ampt – Saturated hydraulic conductivity
Node	Ponded area	Non-zero value

Table 3.9 Initial losses according to the type of surfaces

Type of surface	Minimum initial loss (mm)
Paving	1.5
Flat roof	1.5
Sloped roof	1.0
Grass	5.0
Wooded area and fields	8.0
Forest	15.0

Table 3.10 Initial infiltration capacity (fo)

Type of surface	Initial infiltration capacity (fo) (mm/hr)
	With little or no vegetation			With dense vegetation
	Sandy soil	Loam	Clay soil	Sandy soil	Loam	Clay soil
Completely dry soil	125	75	25	250	150	50
Virtually dry soil	60	40	15	125	75	25
Drained, but not dry soil (field capacity)	40	25	10	80	50	15
Virtually saturated to saturated soil	Values of Table 3.11

Table 3.11 Ultimate infiltration capacity (fc)

Hydrologic soil group(1)	Ultimate infiltration capacity (fc) (mm/hr)
A	35
B	15
C	2
D	0.5

Hydrologic groups A, B, C and D are those defined in the report Classement des séries de sols minéraux du Québec selon les groupes hydrologiques, Rapport final, IRDA, déc. 2013.

Table 3.12 Suction head at the wetting front and saturated hydraulic conductivity

Type of soil	Suction head at the wetting front (mm)	Saturated hydraulic conductivity (mm/hr)
Sand	50	120
Loamy sand	60	30
Sandy loam	110	11
Loam	90	3
Silty loam	170	7
Sandy clay loam	220	2
Clay loam	210	1
Silty clay loam	270	1
Sandy clay	240	1
Silty clay	290	1
Clay	320	0

O.C. 871-2020, s. 30.

Not in force

In force: 2020-12-31

30. The parameters of the computer model must comply with the values of the attributes indicated in Table 3.8 for “General options” type elements.

For the other parameters of the computer model, the values of the attributes, other than the Horton or Green-Ampt attributes, must be determined following a calibration of the model or, failing that, comply with the values indicated in Table 3.8.

For the values of the Horton or Green-Ampt attributes, if onsite data are available, the date must be used or, failing that, the values indicated in Table 3.8 must be complied with.

Table 3.8 Parameters of the SWMM5 computer model

Element of the model	Attribute	Value
General options	Units	L/s or m3/s
General options	Routing model	Dynamic wave
General options	Infiltration model	Horton or de Green-Ampt
General options	Reporting time steps	≤ 1 minute
General options	Routing time steps	≤ 30 seconds
General options	Allow ponding	Activated
Subcatchments	Roughness coefficient (N) – impervious area	Table 3.5
Subcatchments	Roughness coefficient (N) – pervious area
Subcatchments	Depth of depression storage - impervious area	Table 3.9
Subcatchments	Depth of depression storage - pervious area
Subcatchments	Horton – maximum infiltration rate (fo)	Table 3.10
Subcatchments	Horton – minimum infiltration rate (fc)	Table 3.11
Subcatchments	Horton – decay constant (k)	≥ 2
Subcatchments	Green-Ampt – Suction head at the wetting front	Table 3.12
Subcatchments	Green-Ampt – Saturated hydraulic conductivity
Node	Ponded area	Non-zero value

Table 3.9 Initial losses according to the type of surfaces

Type of surface	Minimum initial loss (mm)
Paving	1.5
Flat roof	1.5
Sloped roof	1.0
Grass	5.0
Wooded area and fields	8.0
Forest	15.0

Table 3.10 Initial infiltration capacity (fo)

Type of surface	Initial infiltration capacity (fo) (mm/hr)
	With little or no vegetation			With dense vegetation
	Sandy soil	Loam	Clay soil	Sandy soil	Loam	Clay soil
Completely dry soil	125	75	25	250	150	50
Virtually dry soil	60	40	15	125	75	25
Drained, but not dry soil (field capacity)	40	25	10	80	50	15
Virtually saturated to saturated soil	Values of Table 3.11

Table 3.11 Ultimate infiltration capacity (fc)

Hydrologic soil group(1)	Ultimate infiltration capacity (fc) (mm/hr)
A	35
B	15
C	2
D	0.5

Hydrologic groups A, B, C and D are those defined in the report Classement des séries de sols minéraux du Québec selon les groupes hydrologiques, Rapport final, IRDA, déc. 2013.

Table 3.12 Suction head at the wetting front and saturated hydraulic conductivity

Type of soil	Suction head at the wetting front (mm)	Saturated hydraulic conductivity (mm/hr)
Sand	50	120
Loamy sand	60	30
Sandy loam	110	11
Loam	90	3
Silty loam	170	7
Sandy clay loam	220	2
Clay loam	210	1
Silty clay loam	270	1
Sandy clay	240	1
Silty clay	290	1
Clay	320	0

O.C. 871-2020, s. 30.