OHM Groups. FUNCTIONAL SERVICING REPORT 33 Arkell Road City of Guelph August 5, Prepared By:

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1 Prepared By: OHM Groups FUNCTIONAL SERVICING REPORT 33 Arkell Road City of Guelph August 5, 2015 Guelph Owen Sound Listowel Kitchener Exeter Hamilton GTA 650 Woodlawn Rd. W., Block C, Unit 2, Guelph ON N1K 1B8 P:

2 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD AUGUST 5, 2015 TABLE OF CONTENTS 1. INTRODUCTION SITE INFORMATION PROPOSED DEVELOPMENT Sanitary Sewers Storm Sewers Watermain STORMWATER MANAGEMENT Design Criteria Post-Development Conditions Routing WATER QUALITY CONCLUSIONS... 5 LIST OF FIGURES Figure No. 1 Figure No. 2 Site Location Map Post-Development Drainage Area Plan LIST OF APPENDICES Appendix A Appendix B Post-Development MIDUSS Computer Model Output for the 5 and 100 Year Design Storms and Stage-Storage Discharge Calculation Tables Stormceptor Design Summary I

3 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD AUGUST 5, 2015 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD, GUELPH AUGUST 5, INTRODUCTION In support of the Zone Change Application, this report documents the proposed preliminary site servicing and stormwater management design for the proposed development at 33 Arkell Road in the City of Guelph (City), as shown on Figure No. 1. Van Harten Surveying Inc. completed a topographic survey of the site in August The adjusted legal boundary was provided by Van Harten Surveying Inc. in July The site layout was provided by BJC Architects Inc. in July The existing and proposed site details are shown on the Preliminary Site Grading and Servicing Plan (GMBP Drawing No. SGP). 2. SITE INFORMATION The hectare site is currently zoned Residential Single Detached (R.1B). The site currently includes a two storey detached house, an old farm silo and the stone foundation of an old barn. The subject property is irregular in shape with a frontage of approximately 67 m along Arkell Road and approximately 60 m deep. For the purposes of this report, Arkell Road adjacent to the site is assumed to run east-west and is assumed to be north of the site. The site is bound to the north by the Arkell Road right-of-way. The site is bound to the east by the Arkell Road Bible Chapel and is bound to the west by Hamilton s Corner Garage Ltd. The site is bound to the south by a vacant field. The vacant field is currently being designed as a townhouse development. An existing 5m wide road widening easement runs along the northerly property limit. Under existing conditions the subject property generally slopes from east to west. 3. PROPOSED DEVELOPMENT This Report is in support of a Zone Change Application to change the current Residential Single Detached (R.1B) zone to a General Apartment Zone (R.4A) zone. The proposed development includes a 746m 2 (8,030ft 2 ) apartment building with associated parking and driving areas. 3.1 Sanitary Sewers A proposed 200mm diameter sanitary sewer connected to the existing 200mm diameter sanitary sewer on Arkell Road will service the proposed apartment building. 1 OF 5

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5 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD AUGUST 5, Storm Sewers With the proposed development, the area of impervious surfaces on-site will be increased, increasing the rate of runoff. To offset the increase in runoff rate, we propose to construct an on-site storm sewer system capable of conveying the 5 year design storm to the stormwater management facility located in the northwest corner of the site. The runoff will be attenuated within the stormwater management facility prior to being released to the Arkell Road storm sewer system at a controlled rate. The major design storm is proposed to sheetflow to Arkell Road. 3.3 Watermain A proposed 200mm diameter water service will extend from the existing 400mm diameter watermain on Arkell Road. The proposed 200mm water service will service the apartment building and provide fire flow to the apartment building s sprinkler system. 4. STORMWATER MANAGEMENT 4.1 Design Criteria The stormwater management criteria provided by the City of Guelph used for the analysis of the site is as follows: 1. The 5-year allowable outlet rate of the site is 0.022m 3 /s. 2. The minimum acceptable water quality level of discharge to the municipal collection system is 70% TSS removal. The City of Guelph Chicago Storm parameters used to model the 5 and 100 year design rainfall events for the site are summarized in the following Table No. 1. Table No. 1: City of Guelph - Chicago Storm Parameters Coefficient 5 Year 100 Year A B C R Duration (min) Total Depth (mm) The Horton infiltration method was used in the MIDUSS model. The following parameters summarized in the following Table No. 2 were used according to the City of Guelph Standards. Table No. 2: MIDUSS Horton Parameters Impervious Areas Pervious Areas Maximum Infiltration (mm/hr) Minimum Infiltration (mm/hr) Lag Constant (hr) Depression Storage (mm) OF 5

6 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD AUGUST 5, Post-Development Conditions For post-development analysis purposes, the hectare site was modelled as three (3) drainage catchments. The post-development drainage catchments are shown on Figure No. 2 and described below. The post-development MIDUSS computer modeling is attached in Appendix A. Catchment 100 (0.074 hectares) represents the proposed apartment building s rooftop. Stormwater runoff from Catchment 100 is proposed to be attenuated at a controlled rate by the roof drains. Catchment 100 is modeled with two (2) roof drains, complete with six (6) weirs per drain. The roof leaders are proposed to drain directly to the proposed stormwater management facility located in the northwest corner of the site. Catchment 100 stage-storage-discharge calculation table is presented in Appendix A. Catchment 200 (0.313 hectares) represents the parking, driving and grassed areas surrounding the apartment building. Runoff from Catchment 200 is proposed to drain to the proposed stormwater management facility located in the northwest corner of the site. Runoff stored within the stormwater management facility will be attenuated by a 100mm orifice plate on the outlet of the stormwater management facility prior to discharging to the Arkell Road storm sewer system. Catchment 200 stagestorage-discharge calculation table is presented in Appendix A. The proposed stormwater management facility is proposed to be 18m long x 8m wide and 1m deep stone storage gallery with approximately 58m 3 of runoff storage. Catch basins are proposed in the parking and driving area to collect the runoff from the asphalt surfaces. The stormwater management facility is expected to provide stormwater storage for all storms up to, and including, the 5 year design storm. Catchment 300 (0.031 hectares) represents the south and west sloped portions of the site that cannot drain to the proposed on-site stormwater management facility. Runoff from Catchment 300 is proposed to drain overland un-attenuated to the neighbouring southerly and westerly properties. All runoff from the parking and driving surfaces will drain through a Stormceptor 300i prior to discharging to the proposed stormwater management facility located in the northwest corner of the site. 4.3 Routing The hydrologic model MIDUSS was used to create the design storm runoff hydrographs and to route the hydrographs. The routing results for the proposed apartment building rooftop are summarized in Table No. 3 below. 3 OF 5

7 FUNCTIONAL SERVICING REPORT OHM GROUPS 33 ARKELL ROAD AUGUST 5, 2015 Table No. 3: Proposed Apartment Building Rooftop (Catchment 100) - Stage-Storage-Discharge Capacity Storage and Control Peak Flow m³/s Available Capacity Storage Volume m³ Storage Elevation m Peak Flow m³/s Actual Capacity Used Storage Volume m³ Storage Elevation m Roof Drain Year Year Overflow The routing results for the proposed stormwater management facility are summarized in Table No. 4 below. Table No. 4: Proposed Stormwater Management Facility (Catchment 200) - Stage-Storage-Discharge Capacity Storage and Control Peak Flow m³/s Available Capacity Storage Volume m³ Storage Elevation m Peak Flow m³/s Actual Capacity Used Storage Volume m³ Storage Elevation m Orifice Year Top of Stone Weir Year Overflow A summary of the post-development peak flow from the site for the 5-year and 100-year design storm events are provided in Table No. 5 below. Table No. 5: Peak Flow from Site (m 3 /s) 5 Year 100 Year Catchment 200 (SWM Facility) Catchment 300 (Un-attenuated) Total Flow from Site (with Hydrograph lag) As shown in the attached MIDUSS modelling, the outlet hydrograph peaks from Catchment 200 and 300 do not coincide with each other due to the hydrograph lag of the separate Catchments. As shown in Table No. 5 above, with the implementation of the proposed stormwater management system, the 5-year postdevelopment peak runoff rate from the site, including the hydrograph lag, is less than the allowable outlet rate of 0.022m 3 /s. 4 OF 5

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9 Appendix A Post-Development MIDUSS Model Output and Stage-Storage-Discharge Calculation Tables

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16 Appendix B Stormceptor Design Summary

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