D. B. G R A Y E N G I N E E R I N G I N C.

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1 STORMWATER MANAGEMENT REPORT 948 Hunt lub Road Ottawa, Ontario Report No SWM August 27, 2012 Revised April 21, 2014 Revised December 9, 2014 Revised April 14, 2015 D. B. G R A Y E N G I N E E R I N G I N. Stormwater Management - Grading & Drainage - Storm & Sanitary Sewers - Watermains 700 Long Point ircle Ottawa, Ontario K1T 4E9 dbgray@rogers.com 1

2 STORMWATER MANAGEMENT REPORT 948 Hunt lub Road Ottawa, Ontario This report addresses the stormwater management requirements of a proposed 35 unit three-storey apartment building development located on 2199 sq.m. of land at 948 Hunt lub Road in Ottawa. The proposed development is the second phase of a two phase development and is considered a revision to an existing approved site plan for 934 Hunt lub Road. This report forms part of the stormwater management design for the proposed development. Also refer to drawing SG-1 & SG-2, prepared by D. B. Gray Engineering Inc. WATER QUALITY: The Rideau Valley onservation Authority (RVA) commented that the municipal storm sewers fronting the subject property on Hunt lub Road run to the east, outletting either at the upstream end of the municipal Sawmill reek onstructed Wetland Facility or into a low area of publicly owned land adjacent the Airport Parkway in either case, no additional quality controls are required for the purpose of surface water quality protection. No permanent on-site quality control measures are proposed. During construction, an erosion and sediment control plan has been developed (see notes 2.1 to 2.5 on drawing SG-2). In summary, to filter out construction sediment, geotextile fabric will be placed between the grate and frame of all existing catch basins adjacent to the site and all new catch basins as they are installed. WATER QUANTITY: The stormwater management criteria for quantity control are to control the post development peak flows for the 5-year and 100-year storm events to peak flows during the 5-year storm event using a pre-development runoff coefficient or runoff coefficient of 0.5, whichever is less. It is calculated that the pre-development conditions reflect a 5-year runoff coefficient of Using the Airport Formula for sheet flow it is calculated that the existing time of concentration is 13.0 minutes. Based on the Rational Method the pre-development (existing) peak flow is l/s. 2

3 alculations are based on the Rational Method. The runoff coefficients for the 100 year event were increased by 25% to maximum Stormwater will be stored within the development; on the roof of the proposed building; on the surface in a car park area; and underground in catch basins, manholes and sewer pipes. The runoff from the perimeter of the property (Drainage Area I 511 sq.m.) will be allowed to flow uncontrolled off the site. The flow from these areas is calculated at 10 minutes concentration. Each of three roof drains will be flow control type installed with a parabolic shaped slotted weir (1 slot per weir drain at l/s per mm per slot - 5 USgpm per inch per slot) causing the storm water to pond on the roof (Drainage Areas II & III 283 sq.m. & 604 sq.m.). An inlet control device (ID) located at the outlet pipe of B/MH-2 will control the release of stormwater from Drainage Area IV (801 sq.m.). The ID will restrict the flow and force the stormwater back up into the upstream sewer pipes, catch basin and manholes and onto the surface above catch basins B-1 and B/MH-2. Stormwater released through the roof drains and ID will be conveyed off the site via a an existing 300mm storm sewer connection that also serves 934 Hunt lub Road. The existing 300mm storm sewer connects to an existing 1800mm municipal storm sewer in Hunt lub Road. The ID shall be a Hydrovex "VHV Vertical Vortex Flow Regulator" and shall be sized by the manufacturer for a discharge rate of 9.95 l/s at 3.05 m head. It is calculated that an orifice area of 7854 sq.mm. (100 mm in diameter) and a discharge coefficient of will restrict the outflow rate to 9.95 l/s at a head of 3.05 m. Based on this orifice the maximum outflow rate for the 1:5 year storm event is calculated to be 9.84 l/s at 2.98 m. EXISTING ATH BASIN B#4: The stormwater management design developed by Stantec Engineering for 934 Hunt lub Road (now built) included an IBEX Type A ID to be installed in the outlet pipe of the catch basin B#4 located in the southeast corner of 934 Hunt lub Road. Based on Stantec s calculations the drainage area for this catch basin is 140 sq.m. with a runoff coefficient of 0.20 (i.e. grass). During the 100-year storm event we calculate that at 15 minutes time of concentration the runoff from this area is 1.39 l/s. The IBEX Type A ID will release l/s without any water ponding above the catch basin, so in this scenario there would be no surface ponding. 3

4 However the actual drainage area for this catch basin includes the south side of the roof and the rear yard of 948 Hunt lub Road. It is approximately 1500 sq.m. in area with a runoff coefficient of During the 100-year storm event we calculate that at 15 minutes time of concentration the runoff from this area draining into B#4 is actually l/s. However since the IBEX Type A ID will release l/s there would still be no surface ponding. The proposed drainage area for this catch basin includes the southern perimeter of 948 Hunt lub Road. It is approximately 270 sq.m. in area with a runoff coefficient of During the 100-year storm event we calculate that at 15 minutes time of concentration runoff from this area is actually 2.68 l/s. Again, since the IBEX Type A ID will release l/s there would still be no surface ponding. ONLUSIONS: WATER QUALITY: The Rideau Valley onservation Authority (RVA) has commented that no on-site quality control measures are required. No permanent control measures are proposed. An erosion and sediment control plan as been developed to be implemented during construction WATER QUANTITY: One Hundred Year Storm Event: The maximum allowable release rate for the one hundred year storm event for the site is l/s. The post-development release rate for the 100-year storm event is calculated to be l/s. Therefore the maximum post development release rate for the 100-year storm event is equal to the maximum permitted release rate. A maximum stored volume of cu.m. is required to achieve the post development release rate. Five Year Storm Event: The maximum allowable release rate for the five year storm event for the site is l/s. The post-development release rate for the 5-year storm event is calculated to be l/s. Therefore the maximum post development release rate for the 5-year storm event is less than the maximum permitted release rate. A maximum stored volume of cu.m. is required to achieve the post development release rate. 4

5 Summary Tables ONE HUNDRED YEAR EVENT Drainage Area AREA I (Uncontrolled flow off site) AREA II (East Roof) AREA III (West Roof) Maximum Maximum Maximum Allowable Release Volume Release Rate Stored Rate l/s l/s cu.m AREA IV TOTAL FIVE YEAR EVENT Drainage Area AREA I (Uncontrolled flow off site) AREA II (East Roof) AREA III (West Roof) Maximum Maximum Maximum Allowable Release Volume Release Rate Stored Rate l/s l/s cu.m AREA IV TOTAL

6 STORMWATER MANAGEMENT ALULATIONS The orifice calculations are based on the following formula: Q = d x A o 2gh x 1000 where: Q = flowrate in ltires per second d = coefficient of discharge A o = orifice area in sq.m. g = 9.81 m/s2 h = head above orifice in meters Flow control roof drain calculations are based on the following formula: Q = N x S x d x F where: Q = flowrate in ltires per second N = number of roof drains S = slots per weir d = pond depth at roof drain in mm F = flowrate through each slot litres per second per mm pond depth (5 USgpm per inch) Storage calculations on the roof and in the parking area are based on the following formula for volume of a cone: V = (A x d)/3 where: V = volume in cu.m. A = ponding area in sq.m. d = ponding depth in meters alculations for sub-surface storage (manholes and sewer pipes) are based on the following formula for volume of a cylinder: V = L x Pi x (d/2) 2 where: V = volume in cu.m. L = depth of water in manhole or length of pipe in meters d = diameter of manhole (1.22 m) or pipe in meters 6

7 948 Hunt lub Road Ottawa, Ontario REVISED REVISED 27-Aug Apr Nov-14 STORM WATER MANAGEMENT ALULATIONS Rational Method ONE HUNDRED YEAR EVENT Maximum Allowable Release Rate Five Year Event Pre-development (Existing) Development onditions Roof Area: 313 sq.m Asphalt/oncrete Area: 379 sq.m Landscaped: 1507 sq.m Total atchment Area 2199 sq.m Time of oncentration: Tc = Sheet Flow Airport Formula 3.26 (1.1 - ) (L) 1/2 min Sw 0.33 Runoff oefficient (): 0.42 Existing (see above) Sheet Flow Distance (L): 54 m Slope of Land (Sw): 2 % Time of oncentration (Sheet Flow): 13.0 min Area (A): 2199 sq.m. Time of oncentration: 13.0 min. Rainfall Intensity (i): 91 mm/hr (5 year event) Runoff oeficient (): 0.42 Existing (see above) or 0.5 which ever is less Flow Rate (2.78Ai): l/s DRAINAGE AREA I (Uncontrolled Flow Off Site): Roof Area: 20 sq.m Asphalt/oncrete Area: 33 sq.m Landscaped: 458 sq.m Total atchment Area 511 sq.m Area (A): 511 sq.m. Time of oncentration: 10 min. Rainfall Intensity (i): 179 mm/hr (100 year event) Runoff oeficient (): 0.33 Flow Rate (2.78Ai): 8.29 l/s 7

8 DRAINAGE AREA II (East Roof): (ONE HUNDRED YEAR EVENT) Roof Area: 283 sq.m Paved Area: 0 sq.m Landscaped Areas: 0 sq.m Total atchment Area 283 Ave No. of Roof Drains: 1 Slots per Wier: l/s/mm/slot (5 USgpm/in/slot) Depth at Roof Drain: 137 mm Maximum Release Rate 1.70 l/s Pond Area: 222 sq.m. Achieved Vol: cu.m. Max. Vol. Required: cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

9 DRAINAGE AREA III (West Roof): (ONE HUNDRED YEAR EVENT) Roof Area: 604 sq.m Paved Area: 0 sq.m Landscaped Areas: 0 sq.m Total atchment Area 604 Ave No. of Roof Drains: 2 Slots per Wier: l/s/mm/slot (5 USgpm/in/slot) Depth at Roof Drain: 137 mm Maximum Release Rate 3.40 l/s Pond Area: 484 sq.m. Achieved Vol: cu.m. Max. Vol. Required: cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

10 DRAINAGE AREA IV (ONE HUNDRED YEAR EVENT) Roof Area: 0 sq.m Asphalt/oncrete Area: 777 sq.m Landscaped: 24 sq.m Total atchment Area 801 sq.m Storage in MH's & B's Water Elevation: m Invert Depth m m B/MH cu.m. ID Invert: m B cu.m. (Outlet Pipe OF B/MH-2): Head: 3.05 m Storage in Sewer Pipes Diam. Length mm m Orifice Diameter 100 mm cu.m. Orifice Area: 7854 sq.mm. Surface Storage Above atch Basin Area Depth B/MH cu.m. oefficient of Discharge: B cu.m. Max. Release Rate: 9.95 l/s Achieved Vol: cu.m. Max. Vol. Required: cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

11 FIVE YEAR EVENT Maximum Allowable Release Rate Five Year Event Pre-development (Existing) Development onditions Roof Area: 313 sq.m Asphalt/oncrete Area: 379 sq.m Landscaped: 1507 sq.m Total atchment Area 2199 sq.m Time of oncentration: Tc = Sheet Flow Airport Formula 3.26 (1.1 - ) (L) 1/2 min Sw 0.33 Runoff oefficient (): 0.42 Existing (see above) Sheet Flow Distance (L): 54 m Slope of Land (Sw): 2 % Time of oncentration (Sheet Flow): 13.0 min Area (A): 2199 sq.m. Time of oncentration: 13.0 min. Rainfall Intensity (i): 91 mm/hr (5 year event) Runoff oeficient (): 0.42 Existing (see above) or 0.5 which ever is less Flow Rate (2.78Ai): l/s DRAINAGE AREA I (Uncontrolled Flow Off Site): Roof Area: 20 sq.m Asphalt/oncrete Area: 33 sq.m Landscaped: 458 sq.m Total atchment Area 511 sq.m Area (A): 511 sq.m. Time of oncentration: 10 min. Rainfall Intensity (i): 104 mm/hr (5 year event) Runoff oeficient (): 0.27 Flow Rate (2.78Ai): 4.02 l/s 11

12 DRAINAGE AREA II (East Roof): (FIVE YEAR EVENT) Roof Area: 283 sq.m Paved Area: 0 sq.m Landscaped Areas: 0 sq.m Total atchment Area 283 Ave No. of Roof Drains: 1 Slots per Wier: l/s/mm/slot (5 USgpm/in/slot) Depth at Roof Drain: 105 mm Maximum Release Rate 1.30 l/s Pond Area: 130 sq.m. Achieved Vol: 4.54 cu.m. Max. Vol. Required: 4.54 cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

13 DRAINAGE AREA III (West Roof): (FIVE YEAR EVENT) Roof Area: 604 sq.m Paved Area: 0 sq.m Landscaped Areas: 0 sq.m Total atchment Area 604 Ave No. of Roof Drains: 2 Slots per Wier: l/s/mm/slot (5 USgpm/in/slot) Depth at Roof Drain: 105 mm Maximum Release Rate 2.61 l/s Pond Area: 285 sq.m. Achieved Vol: 9.98 cu.m. Max. Vol. Required: 9.98 cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

14 DRAINAGE AREA IV (FIVE YEAR EVENT) Roof Area: 0 sq.m Asphalt/oncrete Area: 777 sq.m Landscaped: 24 sq.m Total atchment Area 801 sq.m Storage in MH's & B's Water Elevation: m Invert Depth m m B/MH cu.m. ID Invert: m B cu.m. (Outlet Pipe OF B/MH-2): Head: 2.98 m Storage in Sewer Pipes Diam. Length mm m Orifice Diameter 100 mm cu.m. Orifice Area: 7854 sq.mm. Surface Storage Above atch Basin Area Depth B/MH cu.m. oefficient of Discharge: B cu.m. Max. Release Rate: 9.84 l/s Achieved Vol: 6.33 cu.m. Max. Vol. Required: 6.33 cu.m. Release Stored Stored Time i 2.78Ai Rate Rate Volume min. mm/hr l/s l/s l/s cu.m

15 From: Jocelyn handler To: DOUGLAS GRAY Sent: Tuesday, April 22, :15 PM Subject: RE: 948 Hunt lub Rd Hello Doug, the municipal storm sewers fronting the subject property on Hunt lub Road run to the east, outletting either at the upstream end of the municipal Sawmill reek onstructed Wetland Facility or into a low area of publicly owned land adjacent the Airport Parkway. Although our mapping data lacks a definite outlet for this stormsewer, in either case, no additional quality controls are required for the purpose of surface water quality protection. Jocelyn Jocelyn handler M.Pl. MIP, RPP Planner, RVA t) x1137 f) jocelyn.chandler@rvca.ca mail: Box Rideau Valley Dr., Manotick, ON K4M 1A5 courier: 3889 Rideau Valley Dr., Nepean, ON K2 3H1 This message may contain information that is privileged or confidential and is intended for the use of the individual(s) or entity named above. This material may contain confidential or personal information which may be subject to the provisions of the Municipal Freedom of Information & Protection of Privacy Act. If you are not the intended recipient of this , any use, review, revision, retransmission, distribution, dissemination, copying, printing or otherwise use of, or taking any action in reliance upon this , is strictly prohibited. If you have received this in error, please contact the sender and delete the original and any copy of the and any print out thereof, immediately. Your cooperation is appreciated. From: DOUGLAS GRAY [mailto:dbgray@rogers.com] Sent: Tuesday, April 22, :02 AM To: Jocelyn handler Subject: 948 Hunt lub Rd Hi Jocelyn I am working on a proposed three-storey 35 unit apartment building development located on 2199 sq.m. of land at 948 Hunt lub Rd in Ottawa. Attached is a location map. Please comment and provide recommendations concerning the stormwater quality criteria for this site. Regards, Doug D. B. G R A Y E N G I N E E R I N G I N. Stormwater Management - Grading & Drainage - Storm & Sanitary Sewers - Watermains 700 Long Point ircle Tel: Ottawa, Ontario K1T 4E9 dbgray@rogers.com 15

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