New Retirement Home 6758 & 6766 Rocque Street Orleans, Ontario

Transcription

1 New Retirement Home 6758 & 6766 Rocque Street Orleans, Ontario Site Servicing and Stormwater Management Report By Mohamad Salame, P.Eng. Kamco Technique Ltee. 60 Grand Avenue North Cambridge, Ontario N1S 2K9 Seal and Signature of Engineer: Date: 21 February 2017

2 TABLE OF CONTENTS 1.0 Location Scope of report Methodology Existing site surface conditions Quantity control Post development conditions Rainfall Intensity duration Proposed services to the building ) Water service ) Sanitary service ) Storm service Erosion and sedimentation control Water quantity control Major flow route Water balance Storage calculations provided Conclusion and recommendations. 9

3 1 1. Project Location This report examines the impacts the proposed development will have on the run-off and sedimentation from the site and measures to mitigate those impacts for a proposed residential building development (retirement house) in which located at 6758 and 6766 Rocque Street Ottawa, Ontario, intersection of Rocque Street and St. Pierre Street. The Report has used the following documentation in its preparation: 1. Site Plan prepared by Golden Rock Architecture. 2. The current City of Ottawa Design Guidelines and Drawings. 4. Stormwater Management Planning and Design Manual by the Ministry of the Environment, dated March Scope of report The purpose of this report is to study stormwater management design criteria typically provided in such plans are to: 1. Preserve groundwater and base flow characteristics 2. Prevent undesirable and costly geometric change in the watercourse 3. Prevent any increase in flood risk potential 4. Protect water quality for human uses. 5. Calculate and describe the control measures taken for proposed development to control rain and storm water run-off on the entire property. 6. Identify all issues that require facilities, for the City of Ottawa approvals, including impacts of drainage to the Streets. 3. Methodology In order to successfully complete the storm water management study for this site, the following specific tasks were undertaken: 1) Calculate the allowable runoff rates using rational method. 2) Determine the percent impervious of the site Post-development value = ) Calculate post development runoff hydrographs. 4) Revise the site grades to attain the required on-site storage capacity for run off required. 5) Pre-development of existing site C value = 0.2 chosen based on the project site locations and used for 5 year storm and as recommended by the City. 6) Pre-development C value = 0.5 x 0.4% = 0.2 used for 100 year storm. 4. Existing site surface conditions The site consists of 2007 square meters ( ha) fronting on Rocque Street. The existing site is vacant land grassed areas, heavily vegetated and graded to slope towards southeast of the in which surface runoff water is naturally conveyed toward Bilberry

4 2 Creek. The existing site drains via overland sheet flow to the southeast of the site adjacent and towards to 15m development setback limit as shown on drawing C1. The underlying soil conditions for the site consist of sensitive silty clay overlain by topsoil and silty sand/ sandy silt in places. New proposed storm water management facilities (SWM) has to be implemented to satisfy the criteria outlined by City of Ottawa and control measures have to be incorporated in the design for quality and quantity of the storm water leaving the subject site. We have considered in calculations the development areas that covering proposed buildings, landscaped and parking areas. The wooden areas are excluded form design calculations as it is not affecting the proposed development. 5. Quantity control The site is within the Place D Orléans Town Centre, which allows for a pre-development maximum runoff coefficient of 0.5 and a time of concentration of 20 minutes. The City of Ottawa requires that post-development run-off shall match the pre-development runoff for the year storm events based on a post-development time of concentration of 10 minutes. Any excess runoff will be retained on site and discharged at pre-development rates so the there is no impact on the existing stormwater management regime. 6. Post development conditions The design of storm sewers computed in accordance with jurisdiction of the City of Ottawa. The extent of the proposed development consists of proposed new two retirement home buildings consists of four residential units, and upgrade driveways, parking lot and site grading. Proposed building Following are the criteria of post development conditions: Used Description Area (square meters) Percentage Total building roof area 347 m % Paved services 312 m % Landscaped, etc. 304 m % Total Area 963 m %

5 3 7. Rainfall Intensity Duration Frequency Curve Equation: An IDF (Intensity Duration Frequency) curve is a statistical of the expected rainfall intensity for a given duration and storm frequency. In Ottawa, the IDF curve is derived from Meteorological Services of Canada (MSC) rainfall data taken from the Macdonald- Cartier airport. Rainfall collected from 1967 to 1997 was analyzed using the Gumbel Distribution. The intensity duration frequency equations and data are used for calculating required storm water storage capacity to limit the peak flow. Equation of IDF curves is: I = A / (Td+B) C I is rainfall intensity in mm/hr T is time in hours (use 10 minutes for time of concentration) A, B and C are the shown as below: Return Period A (min) B (min) C (min) (years) Discharge are calculated using Rational Method Formula: Where Q = C I A Q = Runoff Volume, in m 3 / sec A = Area contributing to runoff. In Ha I = Rainfall intensity in mm/hr C = Runoff Coefficient, dimensionless Time of Concentration (T.C.) = 10 min. pre development and 20 for post development. Refer to appendices for the computer printout calculations. The post 5 and 100-yr storm event used the IDF information derived from the City IDF Curves and equations. i. The IDF equations are ii. I (5year) = /(T )*0.814 = mm/hr

6 4 iii. I (100year) = /(T )*0.820 = mm/hr Calculation of the post-development runoff coefficients is be based on the following impermeability factors: 2-10 Year 25 Year 50 Year 100 Year Buildings: Paving: Gravel : Grass/Landscape: The runoff coefficients for the lower figures as recommended by MTO Design chart. The 2-10 year Post Development characteristics for the site are as foloows: Building 347 m 0.90 = Paving 312 m 0.90 = Grass/Landscape 304 m 0.30 = 91.2 TOTAL = The Post Development Impermeability Factor = 684.3/963 = Proposed services to the buildings: 8.1 Water Service: New watermain supply lines is proposed as shown on drawing C2. Two new proposed water lines and meters are to be located in the basement prior to design and recommendation from mechanical consultant engineer in accordance with the jurisdiction of the City of Ottawa. New watermain services to the two buildings is grouped in a common trench to minimize the number of road cuts. Only one water service is connected to the City watermain. City watermeter remote control is located outside the building as indicated on drawings. Water Supply for fire-fighting calculations F = 220.C. (A) 1/2 F = the required fire flow in liters per minute C = Coefficient related to the type of construction = 1.5 wood frame (combustible construction) = 1.0 ordinary construction (masonry wall, combustible floor and interior) = 0.8 non-combustible construction (unprotected structural components) = 0.6 non-combustible construction (protected structural components, floor and roof)

7 5 A = total floor area (all storeys excluding basement at least 50% below grade) Main floor area: 347 m 2 Basement area: 347 m 2 Total area: 694 m 2 F = 220 x 1.0 (694) 1/2 = 5796 L/min F = 5800 L/min (rounded off to the nearest 1,000 L/min) 8.2 Sanitary Service: New 200 diameter sanitary sewer is proposed as shown on drawing C2. There is one sanitary main trench complete with manhole located inside property. Road cuts of new services shall be carried out in accordance with city requirements and reinstatements are required as per City of Ottawa standard detail R10. Weeping tiles drain system is connected to sump pit in basement and pumped to stormceptor manhole as shown on C2. The recommended max-daily domestic flow for the building was calculated using the current City of Ottawa design criteria with a conservative usage: As per Table 4.2 of the guidelines, a typical 2 bedroom unit has 2.1 persons per unit. For 4 units, the expected residential occupancy will be 8.4. A design occupancy of 10 will be used. As per figure 4.3 of the guideline, a design flow of 350L/c/day applies. Foe 10 people, the design flow is therefore 350x10 = 3500L/day, which is equivalent to 0.041L/s. The peak factor, using the Harmon Equation in Figure 4.3, yileds PF=4.41. Since PF need not exceed a value of 4.0, a PF=4.0 will be used. The peak residential flow is therefore 2.28L/s. 8.3 Storm Service: New storm service required most consideration due to increase in impervious surface and grading, resulting increase in storm water run-off from the site. Rational method was used in the calculation, runoff coefficient for impervious surfaces is required and corrected for high intensity storms. The required quantity of water retained over the site from the post development conditions proposed to be stored over the parking area. For storm of higher than 100 years storm event intensity, the water will flow south towards the creek and road nothing will discharge to neighboring properties.

8 6 Storm water discharged and controlled from proposed site development via orifice place installed downstream of control manhole and the oil grit separator stormceptor will clean and remove suspended solids leaving clean water discharged to street sewers. Rain water leader downspouts (RWL) to spill on grade in location as shown on C1 complete with concrete pad and minimum 1.2m away from building. 9. Erosion and Sedimentation Control: The requirement that stormwater is to be treated to enhanced protection levels as detailed in MOE Stormwater Management and Planning Design Manual (2003). MOE requires 80% removal of the suspended fine particles. A new grease manhole is proposed for this site development. In order to minimize the effects of erosion during the grading of the site, sediment control fencing shall be installed around any stockpiles and around catch basin during construction phase. Any sediment that is tracked onto the road way during the course of construction will be cleaned by the contractor. 10. Water Quantity Control: In order to achieve the storm water management requirements for the site, runoff generated from the areas will be controlled with installation of one orifice at outlet of control manhole. The proposed storm water management report (SWM) prepared by Kamco furnished to address City of Ottawa requirements with respect to water quality and run-off control, the proposed residential parking lot is small in area drawing C2 shown proposed catchbasin (CB) connected to new control manhole to discharge to existing street storm sewers. The proposed lot is provided with grease stormceptor manhole, however the water quality measures and the rainwater flow from the site would be classified as clean, free from grease, dirt and suspended solids. An orifice plate is proposed to be installed at storm manhole to control required flow discharge to street mains. The existing woodlands, trees and shrubs located on former open land inside east side of property is to remain as is and shall be protected by installing construction fencing during construction to prevent heavy objects entering the storm system. The existing woodlands areas and street does not have any existing CB s, therefore, sumps or traps will not be required.

9 7 Refer to the enclosed drawings C1, C2, C3, C4 and storm sewer design sheet for an illustration of the proposed system and discharge calculation. Orifice Equation: Q = Cc A sqrt (2g(H 2/3 D)) Where Cc coefficient of contaction (0.630) H head relative to the invert of the orifice D orifice diameter G gravitianal acceleration (9.810) Refer to appendix for each storm event calculations. Sedimentation and erosion controls should be provided during construction using the following technique depending on site development phasing and seasonal considerations: 1) Filter cloth and snow fencing along the property boundaries. 2) Mud mat at the construction entrance. 3) Stone / filter cloth protection on catchbasins. 4) Grassing of all required areas on completion of grading. All sedimentation and erosion control measures should be carried out in accordance with current City of Ottawa and Ministry of Natural Resources guidelines. The control measures should be checked on a regular basis and after each rainfall event and repaired as necessary. Per and Post Development Flows vrs. Storages Summary Table-1 Pre- Development (before construction) Event Control flow rate (m 3 /s) Release rate (m 3 /s) Allowable release rate (m 3 /s) Provided volume storages (m 3 ) 5 yr. Event Not available Wooded lot, Empty site 100 yr. Event Not available Wooded lot, Empty site Required volume storages (m 3 ) Post 5 yr. Event N/A N/A

10 8 Development (after construction) 100 yr. Event 5 yr. Pre value The pre-development and post development release rate generated from areas are the approximately same and storage requirements for post development will be controlled with installation 60 mm diameter orifice plate at main storm control manhole as indicated on drawings. The orifice will control storages on site and acceptable rate discharge to meet the required site conditions. There will be no external drainage flowing towards the site and proposed water storage ponding does not occur in the parking area for 5 or 100 year storm events. The proposed storm water management system for this site development will maintain the pre development (existing) surface and ground water divides for all design storms up to and including the 100 year event of post development. One Hundred Year Storm Event: The requested maximum allowable release rate for the one hundred year storm event for the site is m 3 /s with the most restrictive ICD that can be practically used. The post-development release rate for the 5-year storm event is to be m 3 /s. This is smaller than the requested release rate but it is the best results the can be practically achieved. Five Year Storm Event: The maximum allowable release rate for the five year storm event for the site is m 3 /s. The post-development release rate for the 5-year storm event is calculated to be m 3 /s. Therefore the maximum post development release rate for the 5-year storm used for the site is achieve the post development release rate. 11. Major flow route The major flow route will continue to flow towards southeast of the site in which surface runoff water is naturally conveyed toward Bilberry Creek. The existing site drains via overland sheet flow to the southeast of the site adjacent and towards to 15m development setback limit as shown on drawing C Water Balance Due to the size of the site and the existing underlying soil conditions it is felt that the proposed development will not have an impact on the existing groundwater conditions. 13. Storage calculations provided Roof storage = 0 (No roof storage, slopped roof)

11 9 Parking and inside storm pipe storage: Some of the volume is proposed to be stored in the underground structures as follow: = 8.27 m 3 Structure Depth/Length (m) Area (sq.m.) Capacity (cu.m.) CBMH pipe CB Subtotal 8.27 The remainder of the volume is proposed to be stored on the surface as ponding. The ponding is proposed to be contained within the curbs of the parking lot as shown on the site development drawings. With a ponding elevation of 62.95m for a 100 year average ponding depth of 30mm. = 145 sq.m. (surface ponding area) x 0.03m (average ponding height) = 4.35 m 3 The total available storage on site (for 100 years event) = = m 3 Required 100 yr. storm event storage = 9.7 m 3 The total available storage is m 3, which is greater than 9.7 m 3 and therefore is adequate. The available volume is 12.62/9.7=1.3% of the required volume. 14. Conclusion and recommendations In conclusion, the site development will be provided with a complete storm drain system and site grading. Storm water shall discharge into existing street storm sewer system. 1) In conclusion, the site development will be provided with a complete storm drain system as shown on proposed site servicing drawings. 2) In general the post-development run-off rate increased from pre-development due to increase of proposed site hard surfaces. 3) The new proposed SWM facilities designed to control the release rate as indicated through control flow roof drains and discharged to the street sewers system. 4) The site will be fully developed as detailed on the site servicing plans and Architectural drawings. 5) The site grading is undertaken according to the proposed elevations, details and erosion control measures shown on the enclosed engineering drawing. 6) Upon completion of construction, the site shall be confirmed to the design criteria specified to meet the City of Ottawa requirements.

12 10 7) In my opinion, the storm surface runoff water flow from the new proposed building and parking area will be adequate and will not impact on the performance of existing flow capacity or cause an increase on existing street s main sewers. 8) The proposed storm water management system for this site development will maintain the post development for all design storms up to and including the 100 year events. 9) Post development external storm water discharge path shall remain to match existing as shown on plan. 10) Existing eternal flow path is out of our scope of this report and site development. 11) The water balance for the site will not be impacted by the proposed development. 12) Site inspection during construction is required by a professional engineer. I have included storm water management design calculations for this development. The existing and proposed conditions presented indicate the post development conditions will be improved, this will meet the City of Ottawa requirements and the proposed development can safely be carried out. This report is issued for site plan approval and building permit. It is recommended that: i) The site grading is undertaken according to the proposed elevations, details and erosion control measures shown on the enclosed engineering drawing. ii) The storm water management system CB & MH shall be installed as detailed on the enclosed engineering drawings. iii) The storm water management faculties to be inspected by certified professional engineer during construction. iv) Quality control of the run-off from paved areas will be treated by an oil/grit separator. All of which is respectfully submitted, Kamco Technique Ltee Mohamad Salame, M.A.Sc., P. Eng., Project Manager 21 February 2017

13 Appendices 11

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15 12 Pre-Development Existing land before construction (vacant lot)

16 6758 & 6766 Rocque Street Ottawa, Ontario Residential Building Calculations for Pre developments (Existing Conditions) RAINFALL T.C. (min): 5- Years Storm Event 10 Pre-development C" Pre. 0.2 C, constant < 1.0 C" Post. (same as Pre.) 0.2 C, constant < 1.0 AREAS: ROOF(ha): 0 PAVED (ha) 0 GRASS(ha): TOTAL(ha): Allowable runoff factor "= (Total area x x C Pre x I)" Building roof controlled flow r No buildings "pre-development' 0 cms Total site realse flow rate cms "= (Allowable - (control+uncontroled flow))" Site run-off factor: 0.20 "= (Roof x C" Post) / Total area + (Paved x C Post) / Total area +(Grass x C Post) / Total area"

17 TIME I (mm/hr) Q (cms) STORAGE(cm) Storage Required (m^3): 0.0 Roof Storage Provided (m^3): 0.0 (see drawing C1)

18 6758 & 6766 Rocque Street Ottawa, Ontario Residential Building Calculations for Pre developments (Existing Conditions) RAINFALL T.C. (min): 100- Years Storm Event 10 Pre-development C" Pre. 0.2 C, constant < 1.0 C" Post. (Same as Pre.) 0.2 C, constant < 1.0 AREAS: ROOF(ha): 0 PAVED (ha) 0 GRASS(ha): TOTAL(ha): Allowable runoff factor "= (Total area x x C Pre x I)" Building roof controlled flow r No buildings "pre-development' 0 cms Total site realse flow rate cms "= (Allowable - (control+uncontroled flow))" Site run-off factor: 0.20 "= (Roof x C" Post) / Total area + (Paved x C Post) / Total area +(Grass x C Post) / Total area"

19 TIME I (mm/hr) Q (cms) STORAGE(cm) Storage Required (m^3): 0.0 Roof Storage Provided (m^3): 0.0 (see drawing C1)

20 17 Post-Development Proposed buildings construction

21 6758 & 6766 Rocque Street Ottawa, Ontario Residential Building Storm water calculations RAINFALL 5- Years Storm Event T.C. (min): 10 Pre-development 20 Post-developmen C" Pre C, constant < 1.0 C" Post C, constant < 1.0 AREAS: ROOF(ha): PAVED (ha) GRASS(ha): TOTAL(ha): No wooded area Allowable runoff factor "= (Total area x x C Pre x I)" Building roof controlled flow r 0 cms No roof rain water storages to be proposed on building Total site realse flow rate cms "= (Allowable - (control+uncontroled flow))" Use 5-years Pre. Development release reate Site run-off factor: 0.56 "= (Roof x C" Post) / Total area + (Paved x C Post) / Total area +(Grass x C Post) / Total area"

22 TIME I (mm/hr) Q (cms) STORAGE(cm) Storage Required (m^3): 2.6 Roof Storage Provided (m^3): 0.0 (see drawing C1) Top of Water Elevation (m): (Grade) Orifice plate Inv. Elevation (m): (see drawing C2) Head relative to the orifice invert (m) Q (cms) 'g' Gravitianal acceleration (m/s^2) `C' Coefficient of contraction (Factor) 'D' Orifice diameter (mm) 59 Use minimum orifice plate 60mm diameter installed upstream of pipe to match 100yrs. storm event.

23 6758 & 6766 Rocque Street Ottawa, Ontario Residential Building Storm water calculations RAINFALL 100- Years Storm Event T.C. (min): 10 Pre-development 20 Post-developmen C" Pre %of "C" added C, constant < 1.0 C" Post AREAS: ROOF(ha): PAVED (ha) GRASS(ha): TOTAL(ha): No wooded area Allowable runoff factor "= (Total area x x C Pre x I)" Building roof controlled flow r 0 cms No roof rain water storages to be proposed on building Total site realse flow rate cms Use 5-years Pre. Development release reate Site run-off factor: 0.56 "= (Roof x C" Post) / Total area + (Paved x C Post) / Total area +(Grass x C Post) / Total area"

24 TIME I (mm/hr) Q (cms) STORAGE(cm) Storage Required (m^3): 9.7 Roof Storage Provided (m^3): 0.0 (see drawing C1) Top of Water Elevation (m): (Grade) Orifice plate Inv. Elevation (m): (see drawing C2) Head relative to the orifice invert (m) Q (cms) 'g' Gravitianal acceleration (m/s^2) `C' Coefficient of contraction (Factor) 'D' Orifice diameter (mm) 59 Use minimum orifice plate 60mm diameter installed upstream of pipe to match 100yrs. storm event.

25 Sewer Lines Design Flow Calculations

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37 SANITARY SEWER DESIGN SHEET Design By: MS Date: 21 February 2017 SITE AREA = Ha. PIPE ROUGHNESS: FOR MANNING'S EQUATION UNIT EXTERNAL FLOW = ( L.s.ha) PIPE SIZES: 150mm DIA. Municipality of Ottawa PERCENT FULL: TOTAL PEAK FLOW / CAPACITY MUNICIPAL ADDRESS: 6758 & 6766 Roque Street, Orleans (Ottawa), Ontario PROJECT NAME: Residentail building : 350 L / capita / day PROJECT NO.: LOCATION SANITARY SEWER DESIGN Type Full Qcap. Full Flow DESCRIPTION From To Area Infill Length Diameter Slope of pipe Capacity Velocity Q(d)/Qcap M.H. M.H. (hectares) (L/s) (m) (mm.) (%) Material (L/s) (m/s) Building -1 Building -1 San. MH PVC SDR Building -2 Building -2 San. MH PVC SDR San. MH Street San PVC SDR Total sanitary peak flow generated by the property from two buildings is 2.28 L/sec Refer attached sheet for peak calculations.

38 STORM SEWER DESIGN SHEET - STREET CONNECTION SEWER BY: MS DATE: 21 February 2017 RAINFALL PARAMETERS: A = mm/hr C = minutes SEWER DESIGN: PIPE ROUGHNESS: FOR MANNING'S EQUATION 5 YEAR DESIGN STORM EVENT B = 6.05 mm/hr n = PIPE SIZES: IMPERIAL EQUIVALENT FACTOR Municipality of Ottawa t = minutes PERCENT FULL: TOTAL PEAK FLOW / CAPACITY MUNICIPAL ADDRESS: 6766 Roque Street, Ottawa PROJECT NAME: Proposed residential building S T O R M S E W E R D E S I G N S H E E T PROJECT NO.: LOCATION STORMWATER ANALYSIS STORM SEWER DESIGN A R Time of Flow Rainfall Peak Full Flow Full Flow DESCRIPTION From To Area Runoff Accumulated Concentration Time Intensity Flow Length Diameter Slope Capacity Velocity Building Ex. Street (hectares) Coeff. A*R A*R (min) (min.) (mm/hr) (L/s) (m) (mm.) (%) (L/s) (m/s) Area drain above parking CB CB/MH Stormceptor Street main

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