Blackstone Community Phase 4-8 Functional Servicing Report

Transcription

1 Blackstone Community Phase 4-8 Functional Servicing Report Project # Prepared for: Ontario Inc. Prepared by: Stantec Consulting Ltd.

2 Sign-off Sheet This document entitled Blackstone Community Phase 4-8 Functional Servicing Report was prepared by Stantec Consulting Ltd. ( Stantec ) for the account of Ontario Inc. (the Client ). Any reliance on this document by any third party is strictly prohibited. The material in it reflects Stantec s professional judgment in light of the scope, schedule and other limitations stated in the document and in the contract between Stantec and the Client. The opinions in the document are based on conditions and information existing at the time the document was published and do not take into account any subsequent changes. In preparing the document, Stantec did not verify information supplied to it by others. Any use which a third party makes of this document is the responsibility of such third party. Such third party agrees that Stantec shall not be responsible for costs or damages of any kind, if any, suffered by it or any other third party as a result of decisions made or actions taken based on this document. Prepared by Dustin Thiffault, P.Eng. (signature) Reviewed by Amanda Lynch, P.Eng. (signature)

3 Table of Contents 1.0 INTRODUCTION OBJECTIVE BACKGROUND POTABLE WATER ANALYSIS BACKGROUND PROPOSED WATERMAIN SIZING AND LAYOUT Ground Elevations Water Demand Connection to Existing Infrastructure HYDRAULIC ASSESSMENT Allowable Pressures Fire Flow POTABLE WATER SUMMARY WASTEWATER SERVICING BACKGROUND DESIGN CRITERIA PROPOSED SERVICING STORMWATER MANAGEMENT EXISTING CONDITIONS STORMWATER MANAGEMENT DESIGN Proposed Conditions Design Methodology DEVIATIONS FROM PREVIOUS STUDIES OVERLAND FLOW POST-DEVELOPMENT INFILTRATION GRADING UTILITIES HYDRO ENBRIDGE GAS TELECOMMUNICATIONS APPROVALS EROSION CONTROL GEOTECHNICAL INVESTIGATION CONCLUSIONS AND RECOMMENDATIONS

4 11.1 POTABLE WATER ANALYSIS WASTEWATER SERVICING STORMWATER MANAGEMENT GRADING UTILITIES LIST OF TABLES Table 1: Residential Water Demands Table 2: Institutional Water Demands Table 3: Contributions to Rouncey Road Sanitary Sewer Table 4: Wastewater Connections to Downstream Infrastructure Table 5: Contributions to SWM Ponds 6 and LIST OF FIGURES Figure 1: Approximate Location of Blackstone Phase 4-8 Draft Plan Area LIST OF APPENDICES : HYDRAULIC ANALYSIS EXCERPTS... A.1 : SANITARY SEWER CALCULATIONS... B.2 : STORM SEWER CALCULATIONS... C.3 : GEOTECHNICAL INVESTIGATION... D.4 : DRAWINGS... E.5

5 Introduction 1.0 INTRODUCTION Ontario Inc. (Mattamy (Monarch) Ltd.) has commissioned Stantec Consulting Ltd. to prepare the following Functional Servicing Report for phases 4-8 of the Blackstone Community. The subject property is located northwest of the intersection of Fernbank Road and Terry Fox Drive within the Fernbank Community. The property is currently zoned Development Reserve (DR) with the exception of the proposed school block currently zoned I1A/R3Z, and is bordered by Fernbank Road to the south, Phase 4 of the Fernbank Crossing subdivision (currently under approvals) to the west, Fernbank MSS Ponds 6 and 8 as well as the Monahan Drain to the north, and existing commercial developments to the west. The property is indicated in Figure 1. The proposed residential development comprises approximately 55.1ha of land, and contains a mixture of townhomes, single family units, a secondary and elementary school block, residential condominium blocks, as well as a 1.1ha park. Figure 1: Approximate Location of Blackstone Phase 4-8 Draft Plan Area td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 1.1

6 Introduction 1.1 OBJECTIVE The intent of this report is to build on the servicing principles outlined in the Fernbank Master Servicing Study (MSS) and updated based on existing infrastructure placed as a part of development of adjacent sites to create a servicing strategy specific to the subject property. The report will establish criteria for future detailed design of the subdivision, in accordance with the associated background studies, City of Ottawa Guidelines, and all other relevant regulations. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 1.2

7 Background 2.0 BACKGROUND The following documents were referenced in the preparation of this report: Fernbank Community Design Plan Master Servicing Study (MSS), Novatech Engineering Consultants Ltd., June West Park Pond 6 Stormwater Management Report and Design Brief, IBI Group, March Fernbank Community Ultimate Pond 8 Stormwater Management Facility Design Report, Stantec Consulting Ltd., April Geotechnical Investigation Proposed Residential Development Blackstone Community, Terry Fox Drive Ottawa, Paterson Group Inc., February Servicing Report, Monarch Corporation / Cardel Homes, Blackstone Community Phase 2-3, Stantec Consulting Ltd., October Letter Addendum to Blackstone Phase 2-3, Stantec Consulting Ltd., June Proposed Commercial Development, Terry Fox Drive at Fernbank Road, Serviceability Study, Stantec Consulting Ltd., September Proposed Commercial Development, Terry Fox Drive at Fernbank Road, Stormwater Management Report, Stantec Consulting Ltd., September Servicing Addendum 1180 Terry Fox Drive, Stantec Consulting Ltd., September City of Ottawa Sewer Design Guidelines, 2nd Ed., City of Ottawa, October 2012 City of Ottawa Design Guidelines Water Distribution, Infrastructure Services Department, City of Ottawa, First Edition, July 2010 td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 2.3

8 Potable Water Analysis 3.0 POTABLE WATER ANALYSIS 3.1 BACKGROUND The proposed development is located within Zone 3W of the City of Ottawa s water distribution system. This zone is fed by the Glen Cairn Pump Station. The Fernbank Community Design Plan (CDP) was issued with the Fernbank Master Servicing Study. Proposed watermain sizing for the larger watermains has not changed from that of the CDP, with watermain alignment changing only slightly to reflect the changes in road and lotting alignments. A 300mm diameter watermain exists along Cope Drive immediately east of the Blackstone Community development area, a 300mm diameter main also exists within Rouncey Road to the north and crossing below the Monahan Drain, and a 300mm watermain connection is proposed through the adjacent Fernbank Crossing subdivision to the west. 400mm watermains exist further east along Terry Fox Drive. No watermains currently exist along the adjacent portion of Fernbank Road. 3.2 PROPOSED WATERMAIN SIZING AND LAYOUT The proposed watermain alignment and sizing for this development is shown on Drawing WTR-1 with 203mm diameter and 305mm diameter piping. It should be noted that the pipe layout and sizing for the development is preliminary, and is to be verified upon detailed hydraulic analysis for the development area Ground Elevations The proposed ground elevations of the development range from approximately 97.25m to m. Preliminary grading and elevations have been determined for the site and included on Drawing GP Water Demand The current draft plan for the Blackstone Phase 4-8 Development calls for a total of 423 single units, 284 townhouse units, 92 back-to-back townhouse units, condominium blocks consisting of approximately 224 units, and an estimated total population of 2,932 persons. An additional 9.35ha of institutional development is expected to contribute to overall demands from the proposed watermains within the development. Water demands for the development were estimated using the City of Ottawa s Water Distribution Design Guidelines. For residential developments, the average day (AVDY) per capita td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 3.1

9 Potable Water Analysis water demand is 350 L/cap/d. For maximum day (MXDY) demand, AVDY was multiplied by a factor of 2.5 and for peak hour (PKHR) demand, MXDY was multiplied by a factor of 2.2. For institutional use, the AVDY is based on the area of land use and is shown in the following tables. For MXDY demand, AVDY was multiplied by a factor of 1.5 and for PKHR demand, MXDY was multiplied by a factor of 1.8. The calculated residential water consumption and institutional water consumption is represented in Table 1 and Table 2 for the Blackstone Phase 4-8 development: Table 1: Residential Water Demands Unit Type Units Person/Unit Population AVDY (L/s) MXDY (L/s) PKHR (L/s) Singles Townhomes Back-to-back Condo Block Condo Block Total Table 2: Institutional Water Demands Area (ha) Demand (L/day) AVDY (L/s) MXDY (L/s) PKHR (L/s) High School Elem. School Connection to Existing Infrastructure Potable water supply will be connected to the existing watermains located on Rouncey Road, Cope Drive, and Defence Street. Drawing WTR-1 shows the location of the connection points to the existing watermains. It is anticipated that the development will be phased from east to west and north to south. A minimum of two connections to the surrounding 300mm watermains will be provided as development proceeds to the west and south, with no more than 49 units serviced on a temporary basis via single feed per City guidelines. 3.3 HYDRAULIC ASSESSMENT A hydraulic model was built for the Fernbank MSS analysis in The model assumed two proposed 300mm mains bisecting the Blackstone development, along with existing 400mm and 300mm mains within Terry Fox Drive and Cope Drive. The majority of internal watermains to the Blackstone development were considered as being of 200mm in diameter. As boundary td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 3.2

10 Potable Water Analysis conditions for the area were not available at the time of preparation of this report, anticipated pressures in this development are based on the MSS analysis to meet basic day and peak hour demands. A fire flow analysis was also performed under maximum day conditions (see Appendix A for MSS model results) Allowable Pressures The City of Ottawa Water Distribution Design Guidelines state that the desired range of system pressures under normal demand conditions (i.e. basic day, maximum day, and peak hour) should be in the range of 350 to 552 kpa (50 to 80 psi) and no less than 275kPa (40 psi) at the ground elevation in the streets (i.e. at hydrant level). The maximum pressure at any point in the distribution system is to be no higher than 552kPa (80 psi). As per the Ontario Building Code & Guide for Plumbing, if pressures greater than 552kPa (80 psi) are anticipated, pressure relief measures are required. Under emergency fire flow conditions, the minimum pressure in the distribution system is allowed to drop to 138kPa (20 psi) Fire Flow A maximum fire flow of 19,000 L/min for proposed back-to-back townhomes was assessed based on Fire Underwriters Survey (FUS) requirements, and considered a worst case scenario of wood frame construction, a 600m2 floor plate area, and minimal exposure distances to adjacent structures. Upon receipt of boundary conditions, a fire flow analysis for the proposed system will be performed to verify that such a flow may be provided at nodes adjacent to back-to-back townhomes. Should the 19,000 L/min rate not be achievable, internal fire separations will be proposed to limit FUS fire flow requirements to available levels. It should be noted that as per the City s most recent technical bulletin in regards to fire flow (ISDTB ) for traditional side-by-side towns and row houses constructed in accordance with the OBC, the fire flow requirement shall be capped at 10,000 L/min. As such, nodes that are able to meet the 10,000 L/min fire flow are expected to perform adequately for the proposed development. Required fire flows for residential development blocks were assumed at 10,000 L/min. A final Fire flow assessment will be required at the subdivision approval phase in which local watermains are checked for their ability to provide the objective FUS fire flows, which in turn will be determined based on final unit layouts. Smaller, local internal watermains will need to be assessed and verified as development planning proceeds. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 3.3

11 Potable Water Analysis 3.4 POTABLE WATER SUMMARY The proposed piping alignment and sizing is capable of achieving the level of service in the subdivision based on the hydraulic analysis created at the Master Servicing level: The proposed water distribution system is recommended to include a combination of 305mm and 203mm diameter pipes; During peak hour conditions, the proposed system is capable of operating above the minimum pressure objective of 276kPa (40psi); During fire conditions, the proposed system is capable of providing sufficient fire flows (10,000L/min and above) while maintaining a residual pressure of 138kPa (20 psi) in the majority of the Blackstone Phase 4-8 development. Sizing of internal mains on local streets will be coordinated to ensure a minimum fire flow of 10,000 L/min may be achieved. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 3.4

12 Wastewater Servicing 4.0 WASTEWATER SERVICING 4.1 BACKGROUND As indicated in the Fernbank Master Servicing Study, wastewater servicing for the Blackstone Phase 4-8 Development is conveyed to the Hazeldean Pump Station via two free flow gravity trunks; one running east along the existing Cope Drive, and one running north along Rouncey Road through Phases 1-3 of the Blackstone Development, and to the 1200mm diameter collector sewer within the Trans Canada Trail. The MSS outlines the sanitary servicing requirements for the subject property, and identifies a 250mm trunk sewer through the Blackstone Phase 4-8 Development to service portions of the Fernbank Crossing Development lands to the west. Drainage areas for this link have been modified since the Fernbank MSS was issued, diverting much of the lands within the Fernbank Crossing Development north to a secondary connection to the Rouncey Road sewer (majority of the areas noted as A19, A20 in the MSS) to suit construction timelines. The Sanitary Drainage Plans for the MSS and Fernbank Crossing are included in Appendix B. The current Sanitary Drainage Area Plan for Fernbank Crossing Phase 4 (Novatech, 2017) identifies a future population of and a residential area of 8.28ha forming external drainage west of the proposed Blackstone Community Phase 4-8 that will be conveyed through the development north to the Rouncey Road sanitary sewer connection point. 4.2 DESIGN CRITERIA As outlined in the City s Sewer Design Guidelines, the following design parameters were used to calculate estimated wastewater flow rates and to preliminarily size on-site sanitary sewers: Minimum Full Flow Velocity 0.6 m/s Maximum Full Flow Velocity 3.0 m/s Manning s roughness coefficient for all smooth walled pipes Single Family Persons per unit 3.4 Townhouse Persons per unit 2.7 Extraneous Flow Allowance 0.28 L/s/ha Residential Average Flows 350 L/cap/day Institutional Flows 28,000 L/ha/day Manhole Spacing 120 m Minimum Cover 2.5m In addition, a residential peak factor based on Harmon s Equation was used to determine the peak design flows. Institutional were assigned a peaking factor of 1.5 per Ottawa s Sewer Design Guidelines. For the purposes of this report, a conservative assumption for design flows from the future development blocks located within the Blackstone Phase 4-8 area has been applied to ensure td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 4.5

13 Wastewater Servicing sufficient sizing of downstream infrastructure. In conjunction with estimated flows generated from existing developments within Blackstone, West Park, and Fernbank Crossing subdivisions, external sewers/areas through the overall Blackstone Development were assessed to ensure appropriate sizing of the Rouncey Road sewer (see drainage areas on Drawing SAN-1 and background documents in Appendix B). Table 3: Contributions to Rouncey Road Sanitary Sewer Subdivision Total Area (ha) Residential Area (ha) Blackstone Phase 4-8 (Includes Fernbank Crossing Phase 4) Institutional Area (ha) Blackstone Phase West Park Phase Fernbank Crossing Phase Total Population 4.3 PROPOSED SERVICING The Blackstone Phase 4-8 will be serviced by a network of gravity sewers which will direct wastewater flows north and east to the trunk sewers within Rouncey Road and Cope Drive. Flows from external lands to the west will also be conveyed through the subject property as directed in the MSS. The proposed sanitary sewer design sheet and associated Sanitary Drainage Area Plan can be found in Appendix B & Appendix E respectively. The connection points and associated flows are summarized in Table 4 below, and have been coordinated with the latest available plans for existing downstream sewers. Previously allocated flows for the available connection points are noted in the table below. The allotted flow from MH1000 is based on the Servicing Brief for Blackstone Phases 1-3, whereas allotted flow to MH2000 is based on the MSS assumed inflow from Node 04 to the Cope sewer stub less commercial inflows from adjacent sites. Based on the estimated peak flows from the development, proposed modifications to sanitary sewer layout will not have negative impact on downstream infrastructure. Table 4: Wastewater Connections to Downstream Infrastructure MH ID Total Area (ha) Residential Area (ha) Institutional Area (ha) Population Total Flow (L/s) Alotted Flow (L/s) Total Sewer Dia. (mm) td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 4.6

14 Stormwater Management 5.0 STORMWATER MANAGEMENT 5.1 EXISTING CONDITIONS The proposed development site measures approximately 55 ha in area and is currently undeveloped. The topography across the site is relatively flat and has a gradual downward slope to the northeast. The site is bound by the Monahan Drain to the north, Fernbank Road to the south, existing commercial development to the west and further residential areas to the east. The neighboring lands to the west are currently under design/construction. Existing grades are provided on the conceptual grading plan (Drawing GP-1). In the past, runoff from the eastern half of the proposed draft plan area sheet drained towards Terry Fox Drive, and ultimately to the Monahan Drain. Currently, overland flows from the development are currently captured via temporary engineered channel immediately west of the existing commercial development area and are conveyed to the Monahan Drain. Fernbank Pond 6 receives flows from development areas further west of the proposed lands, and discharge to a realigned Monahan Drain segment running eastwards along the development s northern property line where it intercepts outflows from interim Pond 8 and crosses Terry Fox Drive further east. 5.2 STORMWATER MANAGEMENT DESIGN Proposed Conditions The proposed residential development contains a mixture of townhome and single family units, two school blocks and a centrally located park. The Fernbank stormwater management Pond 6 is located to the northwest of the property, and Pond 8 is located to the northeast. Site sewers for areas west of Rouncey Road and south of Cope drive are to be directed to Pond 6, whereas the remaining minor system areas and overland flow for the entirety of the site are to outlet to the ultimate Pond 8, with drainage areas roughly divided to utilize existing trunk sewer stubs previously installed for the proposed development. Inlet control devices and road sag storage points will be used to restrict inflow rates to the sewer and to provide attenuating surface storage as described in the design briefs for the Pond 6 and Pond 8 tributary areas Design Methodology The design methodology for the SWM component of the development is as follows: General Use of the dual drainage principle (City of Ottawa). Wherever feasible and practical, site-level measures should be used to reduce and control the volume and rate of runoff (City of Ottawa). Assess impact of 2-year storm (using 24hr SCS design event), 5-year storm, and the worst case 100-year storm events in addition to the 100-year events outlined in the City of Ottawa Sewer td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 5.7

15 Stormwater Management Design Guidelines, and climate change scenarios with a 20% increase of rainfall intensity, on the major & minor drainage system (City of Ottawa). Storm Sewer & Inlet Controls Size storm sewers to convey at minimum the 2-year storm event under free-flow conditions using 2012 City of Ottawa I-D-F parameters. Storm sewers servicing collector streets to convey the 5-year storm event. (City of Ottawa.) Restrict inflows to the sewer to the 2-year rate (5-year for collector streets) or as required. Institutional blocks within the development area are to retain additional runoff up to 50m 3 /ha in their respective areas as per Pond 8 recommendations (see Appendix C). Analysis to be conducted using the 100 year 24hour SCS distribution and 3-hour Chicago events (City of Ottawa). 100-year Storm HGL to be a minimum of 0.30 m below building foundation footing (City of Ottawa). Maximum climate change HGL to be lower than proposed basement elevations (City of Ottawa Sewer Design Guidelines (2012)). Surface Storage & Overland Flow No rear-yard ponding volumes to be accounted for in SWM model preparation (City of Ottawa). The product of depth times velocity on streets not to be greater than 0.6 during the 100-year storm (City of Ottawa). Building openings to be above the 100-year water level (City of Ottawa). Total maximum depth of flow under static and dynamic conditions shall be less than 0.35m (City of Ottawa). Major and minor flow to be conveyed to SWM ponds 6 and 8 for quality (80% TSS Removal) and quantity control (Fernbank MSS). Surface storage of 50m 3 /ha in residential areas and 100m 3 /ha in institutional areas to be provided (Pond 8 Design Report). Provide adequate emergency overflow conveyance off-site (City of Ottawa). The site is to be designed using the dual drainage principle, whereby the minor (pipe) system is designed to convey the peak rate of runoff from at minimum the 2-year design storm and runoff from larger events is conveyed by both minor (pipe) and major (overland) channels, such as roadways and walkways, safely off site without impacting proposed or existing downstream properties. In keeping with the inlet restriction criterion (2-year for local sewers, 5-year for collector streets, 10-year for arterial roads), inlet control devices (ICDs) or orifice plates will be specified during the detailed design stage for all street and rear yard catchbasins to limit the inflow to the minor system. Restricted inlet rates to the sewer are necessary to prevent the hydraulic grade line from surcharging storm sewers into basements during major storms. Drawing STM-1 outlines the proposed storm sewer alignment and drainage divides. The major system flows generated from larger events will be safely conveyed to Cope Drive, Street 3, and td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 5.8

16 Stormwater Management ultimately SWM Pond 8 by engineered (overland) channels such as roadways and walkways. Further details of overland flow routes to SWM pond 8 can be found in the Stormwater Management Facility Design Report for Pond 8 (Stantec, 2014). Per the requirements noted in the PCSWMM model prepared as part of the Pond 8 Design Report, it is intended to convey major system flows to Pond 8 providing 50m 3 /ha of surface storage in residential areas and 100 m 3 /ha of surface storage in institutional areas, and to ensure a maximum depth of flow of 0.35m (including static storage depths) as necessary to meet current City of Ottawa SWM criteria. The minor system from the proposed subdivision will be conveyed and modeled up to the point of discharge to Ponds 6 and 8 from the existing storm trunk sewers within Cope Drive (see Drawing STM-1 for locations). Pond 6 has been designed and sized to permit servicing of the proposed development area per IBI s West Park Pond 6 Stormwater Management Report and Design Brief (see Appendix C). Per the report, Pond 6 infrastructure is sufficient to service the development up to a total contributing area of 24.62ha at 56% imperviousness. Given capture of the full 5-year storm event and preliminary drainage areas and runoff coefficients as noted on Drawing STM-1, Pond 6 design criteria can be achieved for the development. Runoff coefficients for the proposed subdivision were estimated as follows, and are to be reassessed as part of detailed design: Singles/Townhomes 0.59 (average of 0.68 and 0.50 for front and rear yard runoff coefficients) Condominium blocks and back-to-back townhomes 0.70 Institutional areas 0.70 Parks 0.40 The general grading of the site will not likely permit additional major system (road sag) storage above the required 50m 3 /ha noted in the Pond 8 report before the 0.35m maximum flow depth is exceeded. As such, the design sheets included as part of Appendix C have been created to permit full capture of the 5-year design event rather than the minimum 2-year per City of Ottawa design criteria. Major system design will be reassessed at the detailed design stage, with the possibility of reducing required storm trunk sewer sizing should additional major system storage be available. A full dual-drainage dynamic model will be prepared as part of detailed design of the subdivision to assess hydraulic gradelines and their freeboard from proposed underside of footing elevations, as well as surface water depths along major system corridors through the subdivision. 5.3 DEVIATIONS FROM PREVIOUS STUDIES Based on the West Park Pond 6 Stormwater Management Report and Design Brief as prepared by IBI Group, a tributary area of 24.62ha at 56% imperviousness (equates to a runoff coefficient C=0.592, and 5-year AxC of ) has been allotted for the Blackstone Phase 4-8 Development (see Post-Development Drainage Area Plan Figure 2 in Appendix C for details). The storm sewer td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 5.9

17 Stormwater Management design sheet within the Fernbank Community Ultimate Pond 8 Stormwater Management Facility Design Report indicates a contributing area of 31.34ha and accumulated 5-year AxC of (not including pond block). Table 5 demonstrates the proposed tributary areas to Pond 6 and 8 for the current draft plan, and demonstrates adherence to target outflow volume criteria. Reduction in proposed Pond 8 tributary area is due to removal of the interim area INT_EXT as noted in the pond 8 report as the construction of Pond 6 has preceded that of the ultimate Pond 8, and will not be required to be serviced to Pond 8 in the interim. Table 5: Contributions to SWM Ponds 6 and 8 Tributary Area Total Area (ha) A x C Allowable A x C Net Change Pond Pond Total Based on the above, peak minor system flow rates to SWM Ponds 6 and 8 are expected to be similar to that assumed during design of the ultimate ponds. As no significant increases in overall runoff volume are anticipated to either pond, overall operating characteristics of the ponds are anticipated to be unaffected. 5.4 OVERLAND FLOW The subject site in its majority maintains overland flow routes to the ultimate SWM Pond 8 via the proposed Cope Drive and Street #3 as depicted in Drawing STM-1. The PCSWMM model for Pond 8 identifies a peak major system flow of approximately 785L/s during the 100 year 3 hour Chicago event for the subdivision along proposed Street 3. A calculation sheet has been prepared based on design examples for gutter flows per Chapter 4 of the MTO Drainage Management Manual, and included as part of Appendix C. The calculation sheet demonstrates that a 0.21m flow depth over crests in Street 3 will be required along with a high-point to highpoint overland slope of 0.35% to ensure proper conveyance of the 785L/s through Street 3 s 18m ROW. Road sags in this region will be limited to 0.14m to ensure overall flow depths do not exceed the required 0.35m maximum, and will be reassessed during detailed design. Drawing GP-1 presents the conceptual grading plan for the site, along with proposed overland flow routes. 5.5 POST-DEVELOPMENT INFILTRATION As stated in the Pond 8 Design Report, development of the Blackstone Phases 4-8 subdivision will require lot level infiltration measures such as infiltration trenches, bio-swales, topsoil amendment, or a combination thereof to provide a target infiltration rate of 95mm/year. Details of the measures to be implemented will form part of the detailed subdivision design. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 5.10

18 Grading 6.0 GRADING The Blackstone Phase 4-8 lands drain predominantly from west to east. Existing drainage for the development is provided by an overland engineered channel that runs from south to north along the eastern property line of the development to the interim Fernbank MSS pond 8. The Master Servicing Study report provided preliminary grading for the Blackstone development which has been included for reference in Appendix E. For the purposes of this report a conceptual grading plan has also been prepared which takes into account anticipated overland flow conveyance, cover over proposed sewers, and grade raise restrictions as identified in the geotechnical investigation (see Section 10.0), as well as existing connection points on Rouncey Road, Defence Street, Fernbank Road, and Cope Drive. The conceptual grading plan has been provided for reference in Appendix E. A detailed grading design will be developed at the time of final design. Detailed grading will adhere to all requirements as outlined in the City of Ottawa guidelines. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 6.11

19 Utilities 7.0 UTILITIES 7.1 HYDRO Accessible Hydro infrastructure exists at the eastern boundary of the site via existing plant within Cope Drive, and along existing 4-party trenches within the Rouncey Road right-of-way, in addition to the existing hydro transmission corridor further north of the property. Overhead transmission lines also exist along Fernbank Road to the south of the development. Exact size, location and routing of hydro utilities will be finalized after design circulation. Transformer locations and positioning of required utility easements will be identified at the detailed design stage. Upgrades to the existing hydro infrastructure along Fernbank Road are anticipated due to the relatively low existing demand on plant in the area. 7.2 ENBRIDGE GAS Similarly to Hydro, existing gas infrastructure exists at the boundaries of the subject site. Exact size, location and routing of gas infrastructure will be finalized after design circulation. 7.3 TELECOMMUNICATIONS Both Bell and Rogers are expected to be able to service the subdivision. Infrastructure locations and easement requirements will be identified as part of the Composite Utility Planning process, following design circulation. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 7.12

20 Approvals 8.0 APPROVALS Ontario Ministry of Environment and Climate Change (MOECC) Environmental Compliance Approvals (ECAs, formerly Certificates of Approval (CofA)) under the Ontario Water Resources Act will be required for proposed on-site storm and sanitary sewers and inlet control devices (Transfer of review) for the proposed development. The ultimate Pond 8 design will also require an ECA under the newly expanded MOECC transfer of review program. The Rideau Valley Conservation Authority should be circulated on such submissions so that CA sign-off may be given and submission of the ECAs may proceed. Design & construction of the urbanized Fernbank Road segments including intersection improvements at the extension of Rouncey Road and Fernbank are expected to be phased along with development of the subdivision at large, and will be subject to RMA processes. A MOE Permit to Take Water (PTTW) may be required for the site as some of the proposed works may be below the groundwater elevation shown in the geotechnical report. The geotechnical consultant shall determine whether a PTTW is required at the detailed design stage / prior to construction. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 8.13

21 Erosion Control 9.0 EROSION CONTROL Erosion and sediment controls must be in place during construction. The following recommendations to the contractor will be included in contract documents. 1. Implement best management practices to provide appropriate protection of the existing and proposed drainage system and the receiving water course(s). 2. Limit extent of exposed soils at any given time. 3. Re-vegetate exposed areas as soon as possible. 4. Minimize the area to be cleared and grubbed. 5. Protect exposed slopes with plastic or synthetic mulches. 6. Provide sediment traps and basins during dewatering. 7. Install sediment traps (such as SiltSack by Terrafix) between catch basins and frames. 8. Plan construction at proper time to avoid flooding. The contractor will, at every rainfall, complete inspections and guarantee proper performance. The inspection is to include: 9. Verification that water is not flowing under silt barriers. 10. Clean and change silt traps at catch basins. A network of cutoff swales and a temporary sediment control basin is to installed to provide appropriate erosion and sediment control during earthworks operations. It is proposed to maintain the current erosion control scheme, and migrate the sediment basin and cutoff swales westwards along with construction phasing for the development. Refer to Erosion and Sediment Control Drawing EC-1 included in Appendix E for the proposed location of silt fences, cutoff swales, temporary sediment basins and other erosion control structures. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 9.14

22 Geotechnical Investigation 10.0 GEOTECHNICAL INVESTIGATION A geotechnical investigation for the development was completed by Paterson Group Inc. in February of The report summarizes the existing soil conditions within the subject area and construction recommendations. For details which are not summarized below, please see the original Paterson report included in Appendix D. Subsurface soil conditions within the subject area were determined through field investigations between December 2006 and March In total, 65 boreholes were drilled and 8 test pits excavated throughout the subject lands. In general soil stratigraphy consisted of topsoil and/or a thin silty sand and clayey silt layer followed by a sensitive silty clay deposit. Bedrock was assumed at depths ranging from 10m to 30m below ground surface. The thickness of the existing topsoil ranged from 0 to 510mm. Groundwater levels were encountered between 0m and 6.8m in depth. It is expected that construction will occur below the existing groundwater table and therefore a permit to take water is required. A permit to take water for the overall Blackstone development was obtained in May 2013, and will expire on August 31, Based on the observed soil conditions, a grade raise restriction of between 0.8m and 2.0m above existing grade was recommended. The conceptual grading plan (Drawing GP-1) demonstrates adherence to the permissible grade raise recommendations, and will be reassessed at time of detailed design. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 10.15

23 Conclusions And Recommendations 11.0 CONCLUSIONS AND RECOMMENDATIONS Based on the preceding information, the following conclusions are summarized below: 11.1 POTABLE WATER ANALYSIS During peak hour conditions, the proposed system is expected to operate above the minimum pressure objective of 276kPa (40psi); The proposed system is capable of providing sufficient fire flow while maintaining a residual pressure of 138kPa (20 psi) in all areas based on hydraulic analysis done at the master servicing level. A final hydraulic analysis is to be completed at time of detailed design; Two 300mm diameter mains are anticipated for the proposed development along future extensions of Cope Drive and Rouncey Road. The remainder of internal watermains are assumed to be 200mm in diameter WASTEWATER SERVICING The Blackstone Phase 4-8 subdivision will be serviced by a network of gravity sewers which will direct wastewater flows north and east through the Rouncey Road and Cope Drive sewers, and ultimately to Hazeldean Pumping Station. External lands to the west will also be conveyed through the subject property as directed in the MSS and revised during design of the Fernbank Crossing development. The proposed sanitary sewer design indicates 2 connection points to the existing downstream Rouncey and Cope sewers, with total estimated peak outflows of 54.4L/s and 19.4L/s respectively. The proposed drainage area to the Rouncey Road sewer has been optimized to utilize remaining residual capacity of the sewer STORMWATER MANAGEMENT The proposed stormwater management plan is in compliance with the goals specified in the background reports and the 2012 City of Ottawa Sewer Guidelines and 2016 Technical Bulletin. Inlet control devices will be proposed to limit inflow from the site area into the minor system to the 5-year storm event based on City of Ottawa IDF curves. The storm sewer hydraulic grade line will be maintained at least 0.30 m below the underside of footing in the subdivision during design storm events up to the 100-year storm. All dynamic surface water depths are to be less than 0.35 m during all storm events up to the 100-year storm. Quality treatment of runoff and quantity control for the development will be provided by the existing downstream SWM pond 6 and proposed ultimate pond 8 adjacent to the Blackstone Development area. The proposed site design will maintain an emergency overland flow route to Pond 8 via Cope Drive and pathway to the pond via Street 3. Future institutional developments within the Blackstone Community will be required to provide on-site storage to 100m 3 /ha within their respective areas while restricting minor system inflows to the 5-year design event as appropriate. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 11.16

24 Conclusions And Recommendations 11.4 GRADING A conceptual grading plan has been prepared taking into account required overland flow conveyance, cover over sewers, hydraulic grade line requirements, and grade raise restrictions as identified in the geotechnical investigation. A detailed grading design will be developed at the time of final design. Detailed grading will adhere to all requirements as outlined in the City of Ottawa guidelines UTILITIES Utility infrastructure exists in the general area of the subject site. Exact size, location and routing of utilities will be finalized at the detailed design stage. td w:\active\ _blackstone community phase 4 to 8\design\report\draft servicing\rpt_ _servicing.docx 11.17