20191303 Ver 1_Bradford Drawdown Split_20191108

Draw Down Calculations Stage Storage Calculations
Bradford Circle Permeable Pavement Reservoir 1
Water Quality Volume(Ft3) 154.2 Total WQv Required Elev. (Ft) Area (sf) Volume(cf)
Top Elevation of Temp Pool (Ft) 337.15 Overflow Elevation 336.82 1230
Orifice Invert Elevation (Ft) 334.97 405.9
Maximum Head (Ft) 2.16 At Centroid of Orifice 337.15 1230
Driving Head Ho(Ft) 1.08 1/2 Maximum Head
Orifice Diameter(in) 0.50 Note-Reservoir Elevations Vary
Orifice Diameter(Ft) 0.04
Orifice Area (Ft2) 0.001
Orifice Coefficient 0.59 WQv 405.9
Orifice Discharge Q(Ft3/s) 0.01 %Voids 0.38
Days to Complete Drawdown 0.27 Between 2 and 5 Days Total WQv Provided(cf) 154.242
Q=CDAV2SH,
Where: Q = Discharge(cfs)
CD = Coefficient of discharge(dimensionless)-see Table 3-8
A = Cross-sectional area of flow at the orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ft/sec2)
Ho = Driving head(ft),measured from the centroid of the orifice area to
the water surface-Note:Usually use Ho/3 to compute
drawdown through an orifice to reflect the fact that head is
decreasing as the drawdown occurs.
Figure 3-3
Schematic section through an orifice
Ho
(me �
A=.7cR2
R,
Table 3-8
Values of Coefficient of Discharge,CD(Malcom,1989)
Enhance Condition CD
Typical default value 0.60
Square-edged entrance 0.59
Concrete pipe,grooved end 0.65
Corrugated metal pipe,mitred to slope 0.52
Corrugated metal pipe,projecting from fill 1.00

Draw Down Calculations Stage Storage Calculations
Bradford Circle Permeable Pavement Reservoir 2
Water Quality Volume(Ft3) 206.9 Total WQv Required Elev. (Ft) Area (sf) Volume(cf)
Top Elevation of Temp Pool (Ft) 336.64 Overflow Elevation 336.31 1650
Orifice Invert Elevation (Ft) 334.47 544.5
Maximum Head (Ft) 2.15 At Centroid of Orifice 336.64 1650
Driving Head Ho(Ft) 1.07 1/2 Maximum Head
Orifice Diameter(in) 0.50 Note-Reservoir Elevations Vary
Orifice Diameter(Ft) 0.04
Orifice Area (Ft2) 0.001
Orifice Coefficient 0.59 WQv 544.5
Orifice Discharge Q(Ft3/s) 0.01 %Voids 0.38
Days to Complete Drawdown 0.36 Between 2 and 5 Days Total WQv Provided(cf) 206.91
Q=CDAJ2gH,
Where: Q = Discharge(cfs)
CD = Coefficient of discharge(dimensionless)-see Table 3-8
A = Cross-sectional area of flow at the orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ft/sec2)
Ho = Driving head(ft),measured from the centroid of the orifice area to
the water surface-Note:Usually use Ho/3 to compute
drawdown through an orifice to reflect the fact that head is
decreasing as the drawdown occurs.
Figure 3-3
Schematic section through an orifice
1;)
time . Q
A=.7cR2
R,
Table 3-8
Values of Coefficient of Discharge,CD(Malcom,1989)
Enhance Condition CD
Typical default value 0.60
Square-edged entrance 0.59
Concrete pipe,grooved end 0.65
Corrugated metal pipe,mitred to slope 0.52
Corrugated metal pipe,projecting from fill 1.00

Draw Down Calculations Stage Storage Calculations
Bradford Circle Permeable Pavement Reservoir 3
Water Quality Volume(Ft3) 140.4 Total WQv Required Elev. (Ft) Area (sf) Volume(cf)
Top Elevation of Temp Pool (Ft) 336.13 Overflow Elevation 335.8 1120
Orifice Invert Elevation (Ft) 333.97 369.6
Maximum Head (Ft) 2.14 At Centroid of Orifice 336.13 1120
Driving Head Ho(Ft) 1.07 1/2 Maximum Head
Orifice Diameter(in) 0.50 Note-Reservoir Elevations Vary
Orifice Diameter(Ft) 0.04
Orifice Area (Ft2) 0.001
Orifice Coefficient 0.59 WQv 369.6
Orifice Discharge Q(Ft3/s) 0.01 %Voids 0.38
Days to Complete Drawdown 0.24 Between 2 and 5 Days Total WQv Provided(cf) 140.448
Q=CDAV2SH,
Where: Q = Discharge(cfs)
CD = Coefficient of discharge(dimensionless)-see Table 3-8
A = Cross-sectional area of flow at the orifice entrance(sq ft)
g = Acceleration of gravity(32.2 ft/sec2)
Ho = Driving head(ft),measured from the centroid of the orifice area to
the water surface-Note:Usually use Ho/3 to compute
drawdown through an orifice to reflect the fact that head is
decreasing as the drawdown occurs.
Figure 3-3
Schematic section through an orifice
Ho
(me �
A=.7cR2
R,
Table 3-8
Values of Coefficient of Discharge,CD(Malcom,1989)
Enhance Condition CD
Typical default value 0.60
Square-edged entrance 0.59
Concrete pipe,grooved end 0.65
Corrugated metal pipe,mitred to slope 0.52
Corrugated metal pipe,projecting from fill 1.00