1956 Altona Road, City of Pickering Functional Servicing and Stormwater Management Report. Marshall Homes. Project # E15031

Transcription

1 1956 Altona Road, City of Pickering Functional Servicing and Stormwater Management Report Marshall Homes Project # E15031 August 2016

2 Table of Contents 1.0 Introduction and Background Existing Conditions Topography and Drainage Sanitary Servicing Water Distribution System Storm Infrastructure Design Criteria Guidelines Sanitary Sewers and Watermains Storm Sewers Stormwater Management Proposed Conditions Lot Grading Sanitary Sewer System Water Distribution System Storm Drainage Minor System Major System Stormwater Management Quantity Control Quality Control Water Balance/Infiltration Sediment and Erosion Control Floodplain Impact and Spill Analysis Conclusions Appendices Appendix A Appendix B Appendix C Appendix D Pre-Development Release Rates Post-Development Uncontrolled Release Rates Stormwater Management Calculations Quality Control Calculations Figures and Drawings Figure 1 Key Plan... 2 Figure 2 Existing Conditions Drainage... 5 Figure 3 Post-Development Drainage... 9 Drawing FSP Functional Servicing Plan... Rear Pocket Drawing FGP Functional Grading Plan... Rear Pocket

3 1.0 Introduction and Background CANDEVCON Limited has been retained by Marshall Homes to provide a functional servicing and grading design and a stormwater management (SWM) strategy for a proposed residential development in the City of Pickering. The developable portion of the site is bounded by Altona Road to the east, an existing residential development to the north, an existing stormwater management facility to the south and Petticoat Creek to the west. The site is located approximately 250m south of Finch Avenue. The developable area of the site has an area of 0.57 ha and is shown on Figure 1. Marshall Homes is proposing to re-zone this site from low density residential to high density residential through the proposed development of stacked townhouses. The proposed development will consist of five blocks of stacked townhouses, a proposed roadway, parking areas, landscaped areas and an amenity area. The following documents were reviewed in preparation of this FSSR: Phase 1 Environmental Site Assessment 1956 Altona Road, Pickering, Ontario prepared by Terrapex Environmental Ltd. (December 2013) Phase 2 Environmental Site Assessment 1956 Altona Road, Pickering, Ontario prepared by Terrapex Environmental Ltd. (December 2013) Assessment of the Altona Road Spill, prepared by Sabourin Kimble and Associates (March 6, 2014) The Corporation of the City of Pickering, Planning & Development Department, Engineering Design Criteria, Storm Sewer Services and Roads (February 2012) The Regional Municipality of Durham Design Specifications for Regional Services (2015) City of Pickering Stormwater Management Design Guidelines (2012) Stormwater Management Planning and Design Manual (SWMP Manual) prepared by the Ministry of Environment (March 2003) Marshall Homes, 1956 Altona Road Development, Functional Servicing and Stormwater Management Report, prepared by GHD Ltd. (June 2015) CANDEVCON LIMITED Page 1 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

4 WOODVIEW AVE. ALTONA RD. ROSEBANK RD. WHITES RD. FINCH AVE 37 STROUDS LN TWYN RIVERS DR. SHEPPARD AVE KINGSTON RD. KINGSTON RD ALTONA ROAD CITY OF PICKERING CANDEVCON LIMITED KEY PLAN FIG.1

5 2.0 Existing Conditions 2.1 Topography and Drainage Based on the topographical survey prepared by Rady-Pentek & Edward Surveying Ltd. (2014), the existing area for the proposed development site gently slopes south-westerly towards Petticoat Creek. The existing drainage conditions are illustrated on Figure 2. The site is currently occupied by a one storey brick dwelling, shed and associated gravel driveway. The pre-development peak flow for the 2 through 100 year storm events for the total drainage area of 0.46 ha was determined using the Rational method and the City s rainfall intensities. Various methods were used in calculating the time of concentration including the Airport Method, Soil Conservation Service Equation, Kirpich s Equation, and Bransby Williams Equation. The Airport Method resulted in the highest time of concentration of 21.9 minutes and was thus used in establishing the pre-development flow rates from the site. Based on the above, the 2 through 100 year pre-development flow rates were calculated and are presented in Table 1 below. Refer to Appendix A of this report for the calculations. Table 1: Pre-development Flow Rates Design Storm Event (Year) Pre-Development Flow Rate (m 3 /s) Refer to Appendix A for calculations 2.2 Sanitary Servicing The existing sanitary sewer system located adjacent to the subject site is illustrated on Drawing FSP and comprises a 250mm diameter sanitary sewer on Altona Road. The existing sanitary sewer system described above is conveyed southerly to the Liverpool Road Pumping Station and ultimately treated in the Duffins Creek Water Pollution Control Plant. 2.3 Water Distribution System The existing watermain system located adjacent to the subject site is illustrated on Drawing FSP and comprises a 300mm diameter watermain on Altona Road. The existing watermain system described above is located in pressure distribution Zone 2 which is supplied by the Rosebank Reservoir. CANDEVCON LIMITED Page 3 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

6 2.4 Storm Infrastructure There is an existing 1200mm storm sewer located along Altona Road discharging to Petticoat Creek south of the subject site; however, the existing site does not drain to this sewer, as outlined above in Section 2.1. The existing storm sewer system located adjacent to the subject site is illustrated on Drawing FSP. CANDEVCON LIMITED Page 4 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

7 PETTICOAT CREEK

8 3.0 Design Criteria 3.1 Guidelines Design guidance is provided in the following documents: The Regional Municipality of Durham Design Specifications for Regional Services (2015) City of Pickering Engineering Design Criteria Manual City of Pickering Stormwater Management Design Guidelines Toronto and Region Conservation Authority Stormwater Management Criteria (2012, Version 1.0) MOE Stormwater Management Planning and Design Manual (2003) 3.2 Sanitary Sewers and Watermains Sanitary sewers and watermains are to be designed in accordance with the Regional Municipality of Durham s Design Specifications for Regional Services (2015). 3.3 Storm Sewers The storm sewer system will be designed to comply with the City of Pickering s Engineering Design Criteria which are described as follows: Convey the 1 in 5 year storm flows without exceeding 80% pipe capacity Sewer flow must be in a subcritical condition (supercritical flow in sewers will not be allowed) Ensure the Hydraulic Grade Line (HGL) during the 100 year storm is a minimum of 300mm below the basement footing elevation The storm sewer shall be designed using the Rational Method and the City of Pickering s IDF data 3.4 Stormwater Management In accordance with TRCA, City of Pickering and MOECC the criteria for SWM for the subject site are as follows: Quantity Control - Control post-development peak flow levels to pre-development peak flow levels for all storms up to and including the 100 year return period event. Quality Control - Provide an Enhanced level of protection for the minor system drainage as per MOECC (minimum 80% total suspended solids removal). Water Balance/ Infiltration - Infiltrate or detain the first 5mm of rainfall to meet TRCA s minimum water balance/infiltration criterion. CANDEVCON LIMITED Page 6 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

9 4.0 Proposed Conditions 4.1 Lot Grading The proposed lot grading and centreline road grades are show on Drawing FGP, in the rear pocket. These target elevations provide guidance for functional design to ensure the overall grading and major drainage function. The proposed types of lot grading for the development are shown on Drawing FGP. Split drainage and backsplit drainage lots will be utilized within the proposed development to accommodate the existing boundary conditions. Lot grading plans for this development will be prepared at the site plan application stage for review by the City of Pickering. 4.2 Sanitary Sewer System A sanitary sewer system will be constructed within the road network to service the proposed townhouse development. The flows from the development will be conveyed via gravity to the existing 250mm dia. sewer on Altona Road. The routing and preliminary sizing of the sanitary sewer to service this development is shown on Drawing FSP, in the rear pocket. 4.3 Water Distribution System The water distribution network for the development will consist of watermains located within the road network. A meter room will be located at the entrance of the development providing fire protection and domestic water supply to the townhouse development. The watermain will connect into the existing 300mm diameter watermain on Altona Road. The routing and preliminary sizing of the watermain to service the development is shown on Drawing FSP, in the rear pocket. 4.4 Storm Drainage Minor System Minor system flows for the proposed development will be designed to comply with the City of Pickering s Engineering Design Criteria. The storm sewers are proposed to capture and convey flows westerly towards Petticoat Creek. The routing and preliminary sizing of the storm sewer to service the development is shown on Drawing FSP, in the rear pocket. The proposed drainage areas are shown on Figure Major System Since post-development flows are required to match pre-development flows, an orifice plate along with an upstream StormTech underground storage chamber (or approved equivalent) are proposed to store and release major system flows to the specified controlled release rate. Refer CANDEVCON LIMITED Page 7 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

10 to Section 4.5 for functional details on the stormwater management strategy for the development. Should the storm sewer become 100% blocked or an event in excess of the 100 year storm occurs, the major system flows will pond and spill towards Petticoat Creek at the south-west limit of the development via the overland flow route as depicted on Drawing FGP. 4.5 Stormwater Management Quantity Control Based on the proposed site plan for the subject development area, post-development runoff rates were calculated for the 2 through 100 year rainfall event. The flowrates were determined utilizing the Rational Method along with the City of Pickering rainfall intensities and a 10 minute time of concentration. The Antecedent Precipitation Factor of 1.1, 1.2 and 1.25 were applied to the runoff coefficient for the 25, 50 and 100 year storm events, respectively, in accordance with the City of Pickering s Stormwater Management Design Guidelines. The post-development flow rates from the site are presented in Table 2 below with calculations presented in Appendix B of this report. Table 2: Post-development Uncontrolled Flow Rates Design Storm Event (Year) Post-development Uncontrolled Flow Rate (m 3 /s) Refer to Appendix B for calculations Since the total post-development peak flows from the site exceed the pre-development levels, on-site detention is required. Due to the minimal available space for a stormwater management facility, site storage will be provided as surface storage within the roadway and parking area and using a StormTech (or approved equivalent) underground storage chamber system. The design of graduated controls to match the post-development release rates to pre-development levels for all storm events is complex within a storm sewer system. As such, for simplification it is proposed to control the 100 year post-development release rate to an allowable release rate equal to the 2 year pre-development flow. An 85mm diameter orifice is proposed to ensure that the total site release rate is less than the allowable release rate. Based on a total controlled release rate of 0.020m 3 /s, approximately 170m 3 of storage is required. Refer to Appendix C for preliminary design calculations. Detailed orifice and storage calculations will be completed as part of detailed design in support of the site plan application. CANDEVCON LIMITED Page 8 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

11 PETTICOAT PETTICOAT CREEK CREEK

12 4.5.2 Quality Control Low Impact Development (LID) measures have been considered in order to provide a treatment train approach. These LID measures described below include lot level and end-of-pipe controls. Lot Level Controls Lot level controls present an opportunity to reduce runoff and promote infiltration at the source. These controls are proposed both on private properties and within the internal condo roadway. Incorporating controls that do not require maintenance can be an effective method in the treatment train approach to stormwater management and will help achieve the recommended 5mm of stormwater retention. Roof Leaders to Grassed Areas - There is potential for rear roof leaders to be directed to grassed areas where lots back onto open spaces (i.e. the townhouse units at the west and north limits of the development). However, based on the City of Pickering Stormwater Management Design Guidelines which say that all lots with frontage less than 12.0m must have roof drains directly connected, it has been proposed to directly connect all roof drains to the storm sewer system at this functional design stage. Extra Topsoil Depth Increasing the typical topsoil depth of 0.15m to 0.30m will minimize local runoff while promoting increased infiltration. Passive Landscaping to Promote Infiltration Planting of gardens and other vegetation designed to minimize local runoff or the use of rainwater as a watering source can be used to reduce rainwater runoff by increasing evaporation, transpiration and infiltration. By promoting infiltration through passive landscaping, stormwater management is provided for the volume of water infiltrated. Passive landscaping can provide significant stormwater management benefits as part of the overall treatment train approach for the subject development. A detailed landscaping plan will be provided as part of the Site Plan Application detailed design. End-of-Pipe Controls Runoff from the first flush or 25mm storm event is required to be treated prior to discharging to the Petticoat Creek. In addition to the previously mentioned passive treatment methods, a treatment train approach (i.e. LID measures in series) is proposed that will provide a TSS removal greater than 80%. The total TSS removal efficiency has been estimated utilizing an equation presented in the North Carolina Department for Water Quality Stormwater BMP Manual for calculating the total pollutant removal efficiency for BMP s or LID s in series. Refer to Appendix D for calculations. Oil & Grit Separator (OGS) Runoff from the subject development will be treated via an OGS. Based on the drainage area of 0.46 ha with an overall imperviousness of 80%, a Stormceptor STC- 750 (or approved equivalent) can provide 80% TSS removal. However, based on both TRCA and City of Pickering Stormwater Management Guidelines, it is assumed that the OGS will only provide removal of 50% TSS. Refer to Appendix D for sizing calculations. CANDEVCON LIMITED Page 10 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

13 Infiltration Gallery This LID measure will provide the opportunity for the total flow from the site impervious areas to infiltrate or be detained in a sub-surface gallery located at the rear of the blocks on the west limits of the property (refer to Figure 3). The gallery will also provide water balance benefits as outlined below in Section Flows that are not able to infiltrate will back up in the storm sewer flow over the weir in the splitter manhole towards the outfall to Petticoat Creek. It is assumed that the infiltration gallery will provide a 75% TSS removal efficiency (refer to Appendix D). Polishing swale/filter Strip Additional quality control is proposed at the outfall to the creek. The controlled flows will be conveyed through a proposed polishing swale which will then discharge to Petticoat Creek. The polishing swale will be designed to conform to the TRCA LID Manual. It is estimated that the swale will provide 40% TSS removal. Based on this treatment train approach to water quality control, it is estimated that a total TSS removal efficiency of approximately 92.5% will be achieved. Refer to Appendix D for calculations Water Balance/Infiltration Due to the small size of the site, it is proposed to infiltrate the first 5mm of rainfall to meet TRCA s minimum water balance/infiltration criteria. Based on the proposed development area of 0.46 ha at 80% imperviousness, a volume of approximately 23m 3 represents 5mm of runoff over the impervious site area. In order to achieve this requirement, it is proposed to infiltrate clean water flows downstream of the OGS along the rear lot line of the most westerly townhouse block (refer to Figure 3). A flow splitter manhole will divert the first flush flows to the infiltration gallery. For larger storm events the flood flows will continue to the outfall to Petticoat Creek. Additionally, if the water does not infiltrate in the gallery, it will back up to the flow splitter manhole and spill towards the outfall. Design details for the infiltration gallery and flow splitter manhole will be provided at the detailed design stage Sediment and Erosion Control Sediment and erosion control practices during construction will include, but not be limited to, standard devices such as silt fences, mud mats, catchbasin buffers and rock check dams. Detailed Sediment and Erosion Control Plans will be prepared in conjunction with the site plan application for the site Floodplain Impact and Spill Analysis As part of the original Functional Servicing and Stormwater Management Report prepared by GHD Ltd., TRCA requested confirmation of the floodline for the proposed development as well as a hydraulic conveyance analysis of the west Altona Road ditch, adjacent to the site during the Regional Storm event. Refer to the revised Functional Servicing and Stormwater Management Report (GHD Ltd., June 2015) for the results of the floodline and spill analysis. CANDEVCON LIMITED Page 11 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

14 The floodline shown on Drawings FSP and Drawing FGP, in the rear pocket, represent the floodline that resulted from the above noted floodplain analysis. Two 450mm diameter culverts are proposed in parallel at the entrance to the subject site to convey the flows in the west Altona Road ditch, as per the above noted analysis. The proposed road grade elevation at the entrance to the site has been established based on the above noted analysis to ensure that overland flow during the Regional event will be conveyed south by the ditch and will not encroach into the proposed development area. No further analysis of the floodplain or spill is presented here. CANDEVCON LIMITED Page 12 Marshall Homes August 2016 Functional Servicing and Stormwater Management Report Our File No. E15031

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16 APPENDIX A Pre-Development Release Rates

17 Project Name 1956 Altona Road Prepared By DB Project No. E15031 Checked By AK Subject Time of Concentration Calculation Area = 0.46 ha C - Runoff Coefficient = 0.35 L -Basin Length = 80 m Sw - Slope = 0.01 m/m Sw - Slope = 1.0 % A - Basin Area = 0.46 ha Airport Method - C < 0.40 Tc (min) Tc (hrs) Tp (hrs) T C = 3.26*(1.1-C)*L 0.5 = S w 0.33 Soil Conservation Service T C = L = V*60 Kirpich - natural basins T C = K*L 0.77 = S w n Bransby Williams - C > 0.40 T C = 0.057*L = S w 0.2 * A 0.1 W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031-SWM Calculation.xlsx 24/08/2016

18 Project Name 1956 Altona Road Prepared By : D.B. Project No. E15031 Checked By : AK Subject Allowable Release Rate 2 to 100 year post development flows from the site must be controlled to pre-development flows to Petticoat Creek. Since the opportunities for a staged outlet control are limited it is proposed to control 100 year post development flows to 2 year pre-development levels. Utilizing the rational method, the allowable release rate can be determined: Q = C I A Q = C = I = A = where, Allowable Release Rate (m 3 /s) Runoff Coefficient Intensity (mm/hr) Area (ha) The Intensity for: Pickering can be calculated as: I = a / (b + t)^c where, I = Intensity (mm/hr) 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year a = Constant = b = Constant = c = Constant = t = Time of Concentration (min) = I = Intensity (mm/hr) Based on the existing land use the pre development flow rates are: Area ID Area Description Area (ha) Runoff Coefficient Flow Rates (m 3 /s) 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year 101 Buildings Gravel Driveway Open Space Total Therefore the 100 year post development flows must be controlled to: m 3 /s. W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031-SWM Calculation.xlsx 24/08/2016

19 APPENDIX B Post-Development Uncontrolled Release Rates

20 Project Name 1956 Altona Road Prepared By : D.B. Project No. E15031 Checked By : AK Subject Post Development Uncontrolled Release Rate Utilizing the rational method, the post development release rate can be determined: Q = C I A where, Q = C = I = A = Flow rate (cms) Runoff Coefficient Intensity (mm/hr) Area (ha) * Antecedent Precipitation Factor of 1.1, 1.2 and 1.25 applied to runoff coefficient for 25, 50 and 100 year storms, respectively. The Intensity for: Pickering can be calculated as: I = a / (b + t)^c where, I = Intensity (mm/hr) 2 Year 5 Year 10 Year 25 Year 50 Year 100 Year a = Constant = b = Constant = c = Constant = t = Time of Concentration (min) = I = Based on the proposed land use the post development flow rates are: Area ID Area Description Area (ha) Flow Rates (m 3 /s) 2 Year 5 Year 10 Year 25 Year 50 year 100 Year Runoff Coefficient Flow Rates (m 3 /s) Runoff Coefficient Flow Rates (m 3 /s) Runoff Coefficient Flow Rates (m 3 /s) Runoff Flow Rates Coefficient (m 3 /s) Runoff Coefficient Flow Rates (m 3 /s) Runoff Coefficient 201 Total Site (Townhouse) Flow Rates (m 3 /s) W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031-SWM Calculation.xlsx 24/08/2016

21 APPENDIX C Stormwater Management Calculations

22 Project Name 1956 Altona Road Prepared By : D.B. Project No. E15031 Checked By : A.K Subject Post Development Controlled Release Rate Area ID Area Description Area A (ha) Runoff Coefficient C Runoff Q Storage Required Vr Maximum Ponding Depth (m) 100 Year Catchment Characteristics Storage Details Control Details Surface Storage Vs Underground Storage (Pipe) Vu/g Underground Storage (Chamber) Vu/g Storage Available Va = Vs+Vp (m 3 /s) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m 3 ) (m 3 /s) 101 Total Site (Townhouse) MH1 85 Vertical Location Size (mm) Type Orifice Release Rate Qo W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031-SWM Calculation.xlsx 24/08/2016

23 Project Name Project No. Subject 1956 Altona Road E15031 Modified Rational Storage Calculation 100 Year Catchment ID = 201 (total drainage area) Time of Concentration (t c ) = 10 minutes Time Step (t 1 ) = 5 minutes Runoff Coefficient (C) = 0.94 Catchment Area (A) = 0.46 ha Target Release Rate (Q o ) = m 3 /s Time Intensity Runoff Storage Rate Required Storage t = t c + t 1 I=a/(t c +b) c Q=CIA Q s = Q - Q o V = Q s t (min.) (mm/hr) (m 3 /s) (m 3 /s) (m 3 ) Year Storage Required = 171 m 3 W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031-SWM Calculation.xlsx 24/08/2016

24 APPENDIX D Quality Control Calculations

25 Project Name 1956 Altona Road Prepared By AK Project No. E15031 Checked By DB Subject BMP/LID In Series TSS and TP Removal Efficiencies TP TSS Removal Efficiency % Removal Efficiency % Constructed Wetland Bioretention Dry Detention Ponds Perforated Pipe Infiltration / Exfiltration System Sand or Media Filters Infiltration Trenches Phosphorous Sorptive Media Sorbtive Media Interceptors Underground Storage Vegetated Filter Strips / Stream Buffers Wet Detention Ponds Permeable Pavement Oil Grit Separator 50 0 Sources: 1.Most TP Removal Efficiencies are from the 2012 MOECC Phosphorus Budget Tool in Support of Sustainable Development for the Lake Simcoe Watershed (Version 2.0, Technical Guidance Manual (prepared by Hutchinson Environmental Services Ltd., Greenland International Consulting Ltd., and Stoneleigh Associates Inc. for the MOECC), unless where otherwise indicated. 2. National Pollutant Removal Performance Database, version 3, updated in 2007 (CWP, 2007a). W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031 LID_WQ-Removal-Eff-Results.xlsx 24/08/2016

26 Project Information & Location Project Name 1956 Altona Rd. Project Number E15031 City pickering State/ Province Ontario Country Canada Date 8/19/2016 Designer Information EOR Information (optional) Name Louie Jakupi Name Company CANDEVCON Company Phone # Phone # ljakupi@candevcon.com Stormwater Treatment Recommendation Detailed Stormceptor Sizing Report 1956 Altona Rd The recommended Stormceptor Model(s) which achieve or exceed the user defined water quality objective for each site within the project are listed in the below Sizing Summary table. Site Name 1956 Altona Rd Recommended Stormceptor Model STC 750 Target TSS Removal (%) 80.0 TSS Removal (%) Provided 82 PSD Rainfall Station Fine Distribution TORONTO CENTRAL The recommended Stormceptor model achieves the water quality objectives based on the selected inputs, historical rainfall records and selected particle size distribution. Stormceptor Model Stormceptor Sizing Summary % TSS Removal Provided % Runoff Volume Captured Provided STC STC STC STC STC STC STC STC STC STC STC STC StormceptorMAX Custom Custom Stormceptor Detailed Sizing Report Page 1 of 7

27 Stormceptor The Stormceptor oil and sediment separator is sized to treat stormwater runoff by removing pollutants through gravity separation and flotation. Stormceptor s patented design generates positive TSS removal for each rainfall event, including large storms. Significant levels of pollutants such as heavy metals, free oils and nutrients are prevented from entering natural water resources and the re-suspension of previously captured sediment (scour) does not occur. Stormceptor provides a high level of TSS removal for small frequent storm events that represent the majority of annual rainfall volume and pollutant load. Positive treatment continues for large infrequent events, however, such events have little impact on the average annual TSS removal as they represent a small percentage of the total runoff volume and pollutant load. Design Methodology Stormceptor is sized using PCSWMM for Stormceptor, a continuous simulation model based on US EPA SWMM. The program calculates hydrology using local historical rainfall data and specified site parameters. With US EPA SWMM s precision, every Stormceptor unit is designed to achieve a defined water quality objective. The TSS removal data presented follows US EPA guidelines to reduce the average annual TSS load. The Stormceptor s unit process for TSS removal is settling. The settling model calculates TSS removal by analyzing: Site parameters Continuous historical rainfall data, including duration, distribution, peaks & inter-event dry periods Particle size distribution, and associated settling velocities (Stokes Law, corrected for drag) TSS load Detention time of the system Hydrology Analysis PCSWMM for Stormceptor calculates annual hydrology with the US EPA SWMM and local continuous historical rainfall data. Performance calculations of Stormceptor are based on the average annual removal of TSS for the selected site parameters. The Stormceptor is engineered to capture sediment particles by treating the required average annual runoff volume, ensuring positive removal efficiency is maintained during each rainfall event, and preventing negative removal efficiency (scour). Smaller recurring storms account for the majority of rainfall events and average annual runoff volume, as observed in the historical rainfall data analyses presented in this section. Rainfall Station State/Province Ontario Total Number of Rainfall Events 3329 Rainfall Station Name TORONTO CENTRAL Total Rainfall (mm) Station ID # 0100 Average Annual Rainfall (mm) Coordinates 45 30'N, 90 30'W Total Evaporation (mm) Elevation (ft) 328 Total Infiltration (mm) Years of Rainfall Data 18 Total Rainfall that is Runoff (mm) Notes Stormceptor performance estimates are based on simulations using PCSWMM for Stormceptor, which uses the EPA Rainfall and Runoff modules. Design estimates listed are only representative of specific project requirements based on total suspended solids (TSS) removal defined by the selected PSD, and based on stable site conditions only, after construction is completed. For submerged applications or sites specific to spill control, please contact your local Stormceptor representative for further design assistance. Stormceptor Detailed Sizing Report Page 2 of 7

28 Drainage Area Total Area (ha) 0.46 Imperviousness % 80.0 Water Quality Objective TSS Removal (%) 80.0 Runoff Volume Capture (%) Oil Spill Capture Volume (L) Peak Conveyed Flow Rate (L/s) Water Quality Flow Rate (L/s) Up Stream Storage Storage (ha-m) Discharge (cms) Up Stream Flow Diversion Max. Flow to Stormceptor (cms) Design Details Stormceptor Inlet Invert Elev (m) Stormceptor Outlet Invert Elev (m) Stormceptor Rim Elev (m) Normal Water Level Elevation (m) Pipe Diameter (mm) Pipe Material Multiple Inlets (Y/N) No Grate Inlet (Y/N) No Particle Size Distribution (PSD) Removing the smallest fraction of particulates from runoff ensures the majority of pollutants, such as metals, hydrocarbons and nutrients are captured. The table below identifies the Particle Size Distribution (PSD) that was selected to define TSS removal for the Stormceptor design. Particle Diameter (microns) Fine Distribution Distribution % Specific Gravity Stormceptor Detailed Sizing Report Page 3 of 7

29 Site Name Drainage Area Total Area (ha) 0.46 Imperviousness % 80.0 Site Details 1956 Altona Rd Infiltration Parameters Horton s equation is used to estimate infiltration Max. Infiltration Rate (mm/hr) Surface Characteristics Width (m) Slope % 2 Impervious Depression Storage (mm) Pervious Depression Storage (mm) 5.08 Impervious Manning s n Pervious Manning s n 0.25 Maintenance Frequency Maintenance Frequency (months) > 12 Min. Infiltration Rate (mm/hr) Decay Rate (1/sec) Regeneration Rate (1/sec) 0.01 Evaporation Daily Evaporation Rate (mm/day) 2.54 Dry Weather Flow Dry Weather Flow (lps) 0 Winter Months Winter Infiltration 0 TSS Loading Function TSS Loading Parameters Buildup/Wash-off Parameters Target Event Mean Conc. (EMC) mg/l Exponential Buildup Power Exponential Washoff Exponent TSS Availability Parameters Availability Constant A Availability Factor B Availability Exponent C Min. Particle Size Affected by Availability (micron) Stormceptor Detailed Sizing Report Page 4 of 7

30 Cumulative Runoff Volume by Runoff Rate Cumulative Runoff Volume Runoff Rate (L/s) Runoff Volume (m³) Volume Over (m³) (%) Stormceptor Detailed Sizing Report Page 5 of 7

31 Rainfall Depth (mm) No. of Events Rainfall Event Analysis Percentage of Total Events (%) Total Volume (mm) Percentage of Annual Volume (%) Stormceptor Detailed Sizing Report Page 6 of 7

32 For Stormceptor Specifications and Drawings Please Visit: Stormceptor Detailed Sizing Report Page 7 of 7

33 Project Name 1956 Altona Road Prepared By AK Project No. E15031 Checked By DB Subject BMP/LID In Series TSS and TP Removal Efficiencies TSS Overall Treatment Efficiency (%) 92.5 E= A + B - Where: E = Overall Treatment Efficiency (%) A = Efficiency of the First or Upstream BMP / LID SWM feature B = Efficiency of the First or Downstream BMP / LID SWM feature (A x B) 100 N.B. Efficiency of Facilities A and B determined, and then calculated in series with Facility C. This 'in series' removal efficiency calculation continues, as you consider additional downstream BMP or LID features. TSS Removal LID/BMP Description Eff. (%) LID1 Oil Grit Separator 50 LID2 Infiltration Gallery 75 LID3 Polishing Swale/Bioretention 40 E (A +B) 87.5 E (A&B + C) 92.5 Equation Reference: North Carolina Department for Water Quality Stormwater BMP Manual. The BMPs in Series total pollutant removal efficiency equation may be found in Section of this Manual. W:\EAST\Projects\2015\E Altona Rd\Water Resources\Calculations\E15031 LID_WQ-Removal-Eff-Results.xlsx 24/08/2016

34 WHITES RD. ROSEBANK RD. WOODVIEW AVE. CREEK PETTICOAT FINCH AVE 37 SHEPPARD AVE KEY PLAN KINGSTON RD. KINGSTON RD. STROUDS LN TWYN RIVERS DR. ALTONA RD.

35 WHITES RD. ROSEBANK RD. WOODVIEW AVE. CREEK PETTICOAT FINCH AVE 37 SHEPPARD AVE KEY PLAN KINGSTON RD. KINGSTON RD. STROUDS LN TWYN RIVERS DR. ALTONA RD.