APPENDIX D. Drainage and Stormwater Management Assessment Memoranda

Transcription

1 APPENDIX D Drainage and Stormwater Management Assessment Memoranda

2 610 Chartwell Road, Suite 300 Oakville, Ontario, L6J 4A9 Tel: (905) Fax: (905) Website: TECHNICAL MEMORANDUM FROM: TO: Bryan Orendorff, M.A.Sc., P.eng. Alvaro Almuina, P.Eng., City of Barrie DATE: September 1, 2017 COPIES: Brent Gotts, P. Eng. OUR FILE: SUBJECT: Highway 400 McKay Road Interchange: Concept for Proposed Stormwater Management 1. Background The City of Barrie retained WSP to complete the Preliminary Design and Class Environmental Assessment (EA) of the proposed Highway 400 McKay Road Interchange in the City of Barrie. The study area is shown in Exhibit 1. The existing McKay Road is a paved rural arterial 2-lane road which crosses Highway 400 via an overpass bridge. At the time of preparation of this memo the McKay Road overpass has been removed but it is being replaced. The proposed improvements include a new interchange, which will be identified as Highway 400 McKay Road Interchange, as well as urbanizing McKay Road within the study limits. It is under the consideration from MTO that the alignment of Highway 400 will be shifted slightly to the west side in this section of the highway, but it has not been decided yet the amount of alignment shift. The alignments of the ramps will be affected by the shift of the highway alignment. Therefore, at this stage of the study, it is not appropriate to finalize the stormwater management strategy due to the fact that the ramp alignments will be revised. Therefore, a technical memorandum has been prepared at this stage of the study, to document the concept of the proposed stormwater management that can be implemented for the quality and quantity treatment of the storm runoff from for the proposed interchange.

3 Exhibit 1: Study Area Page 2

4 Page 3 2. Proposed Works The recommended plan is comprised of the following: A new interchange at McKay Road and Highway 400 A new Highway 400 crossing that connects Salem Road in the west with Lockhart Road in the east Local road widening of McKay Road, Salem Road and Lockhart Road with associated intersection improvements to tie into broader plans for road widening (i.e. other Class EAs currently being prepared by the City of Barrie). MTO is currently undertaking a Preliminary Design Study Update for Highway 400, from 1 km South of Highway 89 to the junction at Highway 11. MTO s update study is revisiting the previously approved plan from 2004 and updating it accordingly to address future (2031) traffic needs. The current traffic projections indicate that the Highway 400 corridor needs to be widened to 10 lanes throughout the majority of the study limits by That study will look at the widening of Highway 400 within these limits to a 10-lane cross-section (including HOV lanes). MTO s Preliminary Design Study Update was still ongoing at the time of preparation of the McKay Road Class EA ESR. It is expected that the McKay Road Interchange will be constructed in advance of MTO s implementation of the ultimate highway widening plan. Therefore, the Recommended Plan for the McKay Road Interchange is based on existing highway conditions. The ultimate interchange configuration will be subject to future review and design by the City of Barrie and MTO based on MTO s completed Preliminary Design Study Update and during the implementation of the highway widening. This ultimate interchange configuration is outside the scope of this assignment. 3. Review of Background Information WSP obtained and reviewed relevant information and mapping obtained from the City of Barrie, MTO, and Lake Simcoe Region Conservation Authority (LSRCA), including the following: Hydrologic Modelling - Hewitts, Sandy, Coe, Mooselnaka, Gilford, Lover s Creek and the City of Barrie Annexation Area, Final Report, Prepared for LSRCA by URS, dated July City of Barrie, Intensification and Annexed Lands Drainage and Stormwater Management Master Plan, Final Report, prepared by AMEC Environment and Infrastructure, dated October Lover s Creek Existing Subcatchment Plan, prepared by AMEC, dated October 2013

5 Page 4 Drainage Memorandum Highway 400 /10 th Line (McKay Road) Underpass Replacement (Work Order ), prepared by AECOM for MTO, dated October 9, Highway 400 Preliminary Design Report, GWP , From 1 km south of Highway 89 northerly 30 km to the Junction at Highway 11, prepared by URS Canada Inc. for MTO, dated May The City of Barrie, Storm Drainage and Stormwater Management Policies and Design Guidelines, dated November LSRCA Technical Guidelines for Stormwater Management Submissions, Draft, dated June MTO Highway Drainage Design Standards, dated Design Criteria and Standards The guidelines and policies used in the assessment of the drainage systems include: The City of Barrie, Storm Drainage and Stormwater Management Policies and Design Guidelines (2009); LSRCA Technical Guidelines for Stormwater Management Submissions (2016); MTO Highway Drainage Design Standards (2008); and MTO Drainage Management Manual (1997); The Ministry of the Environment and Climate Change s Stormwater Management Planning and Design Manual (MOECC Manual, 2003) was also referenced in the assessment of the drainage system. The City of Barrie has prepared stormwater management criteria in a document Storm Drainage and Stormwater Management Policies and Design Guidelines. The sections that are relevant to this study are as follows: a) Stormwater Drainage System Policies and Design Guidelines: This section outlines the City s criteria for drainage systems such as storm sewers, overland flow routes, bridges and culverts, watercourses, etc. According to this: Flow from Road: Road grading must direct flows from the right-of-way to a safe outlet at specified low points. Outlets can be walkways or open sections of road leading to open spaces or river valleys. Roads may be used for major system overland flow conveyance during the Regulatory (i.e. the larger of the 100-yr storm or Hurricane

6 Page 5 Hazel) storm subject to the 0.10 m above crown of road for collector and industrial road and single lane remains to open for arterial roads. Overland Flow Channels: It shall be designed to convey the Regulatory Storm peak flow without flooding adjacent private properties. Appropriate stabilization shall be provided to protect against velocity conditions experienced during the Regulatory Storm and calculations shall be provided to the City for review and approval. The maximum velocities during the 1:5 year and Regulatory storms shall be 1.5 m/s and 2.5 m/s, respectively for sod lined channels. Bridges and Culverts: i. Culverts and bridges crossing arterial roads must be designed to prevent overtopping during the 100-yr storm. Under certain circumstances the City may request protection from overtopping for the Regional Storm. In addition, bridges and culverts shall be designed so there is no increase in the Regulatory flood conditions of the watercourse. ii. All culverts shall be supplied with headwall end protection constructed of interlocking wall systems, concrete, armour stone or other material approved by the City. Design Flow: Design flow for road crossings is the 100-year flow (or Hurricane Hazel, if directed by the city) for arterial roads and the 50-year flow for the collector roads. Erosion Protection: Armour stone, river stone and/or concrete shall be provided at all inlets and outlets to protect against erosion of the watercourse and provide embankment stability. The maximum allowable target channel velocity shall be in accordance with the MTO Drainage Management Manual. Water Course: Watercourses and associated flood plains shall be capable of handling the Regulatory flood run-off as determined by the Conservation Authority. b) Stormwater Management Policies and Design Guidelines: This section outlines the City s policies and design criteria for stormwater management measures design. This section includes guidelines such as: environmental protection, flood and erosion protection, site plans and infill developments, source and conveyance controls, end of pipe controls, stormwater management facilities for quality and quantity control, stormwater management plantings, emerging technologies, and general maintenance requirements.

7 Page 6 c) Requirements for Erosion and Sediment Control during Construction: This section includes a list of required items to control erosion and sediment transport into natural watercourses during construction. d) Guidelines for Hydrologic and Hydraulic Analysis: This section includes analysis guidelines such as City of Barrie IDF data, preferred method for runoff and flow calculations, preferred methods for hydraulic calculations, and water balance criteria. Based on this: 1:2 year, 1:5 year, 1:10 year, 1:25 year, 1:50 year, 1:100 year and the Regional storms shall be applied for quantity control and the 25 mm 4-hour Chicago storm shall be applied for erosion control as required. In order to determine the critical design storms, the SCS Type II (6-hr, 12-hr and 24-hr durations) and the 4-hour Chicago storm distributions for the 1:2 year through 1:100 year return period shall be applied. Bridge and culvert calculations should be completed by computer programs such as CulvertMaster and HEC-RAS or SWMM. The LSRCA has prepared stormwater management criteria in a document LSRCA Technical Guidelines for Stormwater Management Submissions. This document outlines LSRCA requirements for stormwater management such as: a) Stormwater Quantity Control: This section outlines requirements for peak flow control, volume control, major-minor system, and Regulatory Storm conveyance. Based on this: Linear development on sites without restrictions that create 0.5 or greater hectares of new and/or fully reconstructed impervious surfaces, shall capture and retain / treat on site, the larger of the following: i. The runoff from a 12.5 mm event from the fully reconstructed impervious surface and newly constructed impervious area. ii. The runoff from a 25 mm event from the net increase in impervious area on the site. b) Stormwater Quality Control: This section outlines requirements for treatment of suspended solids, phosphorus, winter salt, temperature, and other contaminants. c) Stream Erosion Control: This section outlines requirements for onsite detention to reduce erosion potential on downstream receiving bodies.

8 Page 7 d) Water Balance/Groundwater Recharge: This section outlines requirements for maintaining pre-development infiltration and evapotranspiration rates under proposed development conditions. e) Erosion and Sediment Control: This section outlines requirements for providing an effective erosion and sediment control plan during site disturbance activities. The MTO Highway Drainage Design Standards prescribe standards for designing Surface Drainage Systems (SD) and Water Crossings (WC). The standards that are relevant to this study are as follows: a) SD-12 Freeboard above Adjacent Watercourse or Water Bodies: This standard identifies the minimum required freeboard for roadways that are constructed adjacent to watercourses or waterbodies. b) WC-2: Freeboard and Clearance at Bridge Crossings: This standard identifies the soffit clearance and freeboard for bridges over waterbodies. For the freeway, the soffit clearance and freeboard for the design storm should be 1.0 m or higher. A Desirable Freeboard is measured vertically from the Energy Grade Line elevation of the design flow to the edge of the travelled lane at the low point. This freeboard is a recommended value although it is recognized that, due to site-specific considerations, it is not always feasible to provide this amount. A Minimum Freeboard of 1.0 m measured vertically from the High Water Level of the design flow to the edge of the travelled lane at the low point. c) WC-7 Culvert Crossings on a Watercourse: This standard identifies the desirable and minimum freeboard, minimum clearance and the maximum flood depth at culvert crossings. The Flood Depth at Culverts with a rise less than 3.0 m should not exceed 1.5 times the diameter or rise of the culvert at the upstream face. For culverts with a rise between 3.0 m and 4.5 m the flood depth at the upstream face must not exceed 4.5 m. This standard applies to closed footing culverts and open footing culverts with non-erodible bottoms. d) WC-8 Minimum Culvert Size: This standard identifies the minimum culvert size based on maintenance considerations. The following design objectives were established to minimize the potential impacts of the proposed improvements on the surrounding environment, based on the prevailing policy framework:

9 Page 8 Provide an effective/efficient drainage system; Minimize risk to public safety; Maintain flow paths for upstream lands; Maintain or enhance the quality of storm runoff; Maintain or reduce flood risk for lands within and surrounding the transportation corridor; Impose not negative impact (i.e. no increase in peak flows) to the existing Highway 400 MTO culvert; Minimize future maintenance requirements; and Situate SWM measures on lands available in the transportation corridor. 5. Site Investigation A field investigation was carried out in November The purpose of the site visit was to confirm the existing drainage conditions, local drainage patterns and drainage divides and conditions of any existing culverts. Site visit photographs are provided in Appendix A. 6. Design Storms 6.1 Rainfall IDF Parameters Rainfall Intensity-Duration-Frequency (IDF) parameters for various return period design storms were obtained from the City of Barrie. The parameters, 4-hour, 6-hour, 12-hour, and 24-hour rainfall depths are summarized in Table Storm Distribution Hyetographs for 6-hour, 12-hour, and 24-hour duration storms are provided by the City in SCS storm distribution, and 4-hour in Chicago Storm distribution. The storm duration resulting in the highest peak flows and runoff volumes shall be used for the study. Storm distribution hyetographs as provided by the City are provided in Appendix B. Table 1: Rainfall IDF Data (City of Barrie Stormwater Management Guidelines) Parameter 2-year 5-year 10-year 25-year 50-year 100-year A B

10 Page 9 Parameter 2-year 5-year 10-year 25-year 50-year 100-year C Equation for Rainfall Intensity = / + Rainfall Depth, mm (4 hour) Rainfall Depth, mm (6 hour) Rainfall Depth, mm (12 hour) Rainfall Depth, mm (24 hour) According to the Ministry of Natural Resources and Fisheries Flood Hazard Criteria Zones of Ontario, the project area falls within Zone 1. For this zone, the flood produced by the Hurricane Hazel storm is considered as the Regional Storm event. 7. Existing Drainage Conditions The McKay Road / Highway 400 area is located within the Lover s Creek watershed and slopes eastward toward Lake Simcoe. Soils within the drainage study limits are mostly characterized by Bondhead sandy loam and Tioga sandy loam. Runoff drains easterly toward Highway 400, crosses Highway 400 through a box culvert located approximately 260 m north of McKay Road and joins with the Lover s Creek tributary. Existing land use includes agricultural lands, wooded areas and commercial landscape business. The existing conditions drainage mosaic is shown in Exhibit 2. The drainage boundaries prepared for existing conditions are based on the existing highway and a generally assumed footprint for the proposed future interchange. Under existing conditions, the roadway runoff is conveyed by roadside ditches. On the west side of Highway 400, runoff from Catchments 100, 105, 115, 120 and 130 ultimately drains toward Highway 400, crosses Highway 400 through a box culvert C1 located approximately 260 m north of McKay Road and joins with the Lover s Creek tributary. Runoff from Catchment 110 drain overland in a south-east direction toward Highway 400. On the east side of Highway 400, runoff from Highway 400 Catchment 135 drains northerly via the highway ditch and joins with the Lover s creek tributary. Catchments 140 and 145 consist mostly of vegetative area and runoff from these areas drains overland in a south-east direction. Runoff from Catchment 150 drains overland northerly toward the Lover s Creek tributary.

11 Page Proposed Drainage Conditions Exhibit 3 shows the tentative proposed conditions drainage mosaic which illustrates the proposed catchments based on the tentative alignments of the Highway 400 McKay Road interchange. This proposed conditions plan is as compatible as reasonably possible with the most recently available MTO plans with the goal of limiting future potential rework and minimizing future costs. On the west side of Highway 400, runoff from Catchment 100 drains easterly as in the existing conditions. A grassed swale will be provided to drain the runoff from the roadway Catchment 105. A new Culvert C2 is required at the proposed N-E/W Ramp to drain the combined flows of Catchments 100 and 105. Runoff from Catchment 120 will drain to Catchment 122 via a storm inlet and new Culvert C6 at the proposed W-S Ramp. Runoff from Catchment 122 incudes flows from portions of Highway 400. The combined flows of Catchments 120 and 122 will be directed to a new Culvert C3 at McKay Road which will discharge into the proposed SWM Pond 1 located within the loop of the proposed E-S Ramp. Runoff from roadway Catchments 110 and 115 will be conveyed via storm sewers to discharge to SWM Pond 1. The SWM Pond 1 will provide quality and quantity control of the runoff from Catchments 110, 115, 120, 122 and 125 (total area of 6.04 ha). The controlled outflows will discharge to Catchment 130 where the flows will combine with the flows from Culvert C2. The combined flows will ultimately drain to the Lover s Creek tributary via existing Culvert C1 on Highway 400. On the eastside of Highway 400, runoff from Catchment 135, which includes a portion of Highway 400, will drain to a proposed SWM Pond 2 located within the loop of the proposed W-N Ramp via a new Culvert C4. Runoff from roadway Catchment 145 will also be directed to SWM Pond 2 via storm sewers. The SWM Pond 2 will provide quality and quantity control of runoff from Catchments 135, 140 and 145 (total area of 5.56 ha). The controlled outflows from SWM Pond 2 will drain to Culvert C5 at McKay Road to the east side ditch of Highway 400 and will ultimately drain to the Lover s Creek tributary. The hydrologic analysis of the drainage catchments and the hydraulic analysis of all existing and proposed culverts will be carried out when the alignments of the Highway McKay Road Interchange has been finalized.

12 Page Stormwater Management This section documents the preliminary screening of SWM practices, the increase in pavement areas due to the roadway widening, an assessment of potential impacts, and the proposed SWM facilities to mitigate the impacts. Under existing conditions, McKay Road is a rural road with roadside ditches to convey storm runoff. Under proposed conditions, McKay Road will be widened to four (4) lanes and urbanized with a center median and curb and gutter. The imperviousness of the catchments will increase due to the widening of the road as well as due to the implementation of new ramps. The increase in imperviousness leads to an increase in surface runoff. In order to meet the criteria as discussed in Section 4, a number of mitigation measures are recommended including SWM wet ponds, Enhanced grassed swales, infiltration galleries, and CB Shields. The four (4) primary criteria that the SWM strategy must meet are: a) Quantity Control (no increase in runoff peak flow rates); b) Quality Control (provide treatment measures to remove contaminants from the runoff); c) Erosion Control measures; and d) Volume Control (retain a specified volume of runoff on site) for water balance. Based on the above: Two SWM wet facilities (SWM Pond 1 and SWM Pond 2) are proposed within the loops of the E-S Ramp and W-N Ramp, respectively, to provide both quantity and quality control of the runoff. These SWM ponds will also service a portion of Highway 400. An Enhanced level of quality treatment will be provided by the two wet SWM facilities for most of the roadway catchments including a portion of Highway 400. A CB Shield will be provided within the storm inlet of Catchment 120 before discharging the runoff into an infiltration gallery. As far as possible, extended detention volumes will be provided in the two SWM ponds for erosion control. Wherever necessary, riprap or rock protection will be provided at the culvert outlets. To retain a specified volume of runoff on site for water balance, infiltration galleries are proposed at four locations, as shown in Exhibit 3. The locations of all culverts, SWM facilities, grassed swales, infiltration galleries, etc. are tentative only and will be finalized when the alignments of the Highway McKay Road

13 Page 12 Interchange has been finalized. The SWM strategy will also depend on the SWM measures proposed by the consultant designing the re-alignment of Highway 400. WSP s SWM strategy will required approval from MTO. The quantitative analysis of the SWM facilities such as calculation of permanent pool volumes, active storage volumes, footprint of SWM facilities and the locations, sizes and volumes of infiltration galleries will be determined once the alignments of the Highway McKay Road Interchange has been finalized. 10. Conclusion This technical memorandum provides a conceptual stormwater management strategy that could be implemented in the proposed Highway 400 McKay Road Interchange. MTO s Preliminary Design Study Update was still ongoing at the time of preparation of the McKay Road Class EA ESR. It is expected that the McKay Road Interchange will be constructed in advance of MTO s implementation of the ultimate highway widening plan. Therefore the Recommended Plan for the McKay Road Interchange is based on existing highway conditions. All hydrologic, hydraulic and SWM analyses and design calculations will be undertaken once the alignments of the Highway McKay Road Interchange have been finalized.

14 HIGHWAY ha C1 EXISTING MTO ROW STUDY LIMIT ha ha MCKAY ROAD ha ha STUDY LIMIT MCKAY ROAD ha ha ha ha LEGEND: HIGHWAY ha CATCHMENT BOUNDARY 100 CATCHMENT No ha CATCHMENT AREA DIRECTION OF FLOW EXISTING CONDITIONS DRAINAGE MOSAIC (TENTATIVE) HWY MCKAY ROAD INTERCHANGE EXHIBIT 2

15 HIGHWAY 400 HIGHWAY ha C1 NEW MTO ROW ha TENTATIVE INFILTRATION GALLERY C2 TENTATIVE INFILTRATION GALLERY ha LATERAL OUTLET WITH CB-SHIELD GRASSED SWALE SWM WET POND ha ha McKAY ROAD EAST MCKAY ROAD SWM Pond 1 C3 C5 Pond 2 McKAY ROAD EAST SWM ha MCKAY ROAD BY OTHERS ha BY OTHERS C6 C4 SWM WET POND LEGEND: ha ha CATCHMENT BOUNDARY 100 CATCHMENT No ha CATCHMENT AREA DIRECTION OF FLOW DITCH INLET WITH CB SHIELD ha HIGHWAY ha PROPOSED STORM SEWER PROPOSED GRASSED SWALE TENTATIVE INFILTRATION GALLERY PROPOSED DRAINAGE CROSSING PROPOSED CONDITIONS DRAINAGE MOSAIC (TENTATIVE) HWY MCKAY ROAD INTERCHANGE HIGHWAY 400 EXHIBIT 3

16 MMM Group Limited Salem Road Crossing at Highway 400 Preliminary Design and Class Environmental Assessment Study Drainage and Stormwater Management Report COMMUNITIES TRANSPORTATION December BUILDINGS INFRASTRUCTURE Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December i

17 STANDARD LIMITATIONS This report was prepared by MMM Group Limited (MMM) for the City of Barrie in accordance with the agreement between MMM and the City. This report is based on information provided to MMM which has not been independently verified. The disclosure of any information contained in this report is the sole responsibility of the client. The material in this report, accompanying spreadsheets and all information relating to this activity reflect MMM s judgment in light of the information available to us at the time of preparation of this report. Any use which a third party makes of this report, or any reliance on or decisions to be made based on it, are the responsibility of such third parties. MMM accepts no responsibility for damages, if any, suffered by a third party as a result of decisions made or actions based on this report. MMM warrants that it performed services hereunder with that degree of care, skill, and diligence normally provided in the performance of such services in respect of projects of similar nature at the time and place those services were rendered. MMM disclaims all other warranties, representations, or conditions, either express or implied, including, without limitation, warranties, representations, or conditions of merchantability or profitability, or fitness for a particular purpose. This Standard Limitations statement is considered part of this report. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December i

18 TABLE OF CONTENTS 1.0 INTRODUCTION Project Description and Purpose Proposed Works Background Information Design Criteria and Standards Site Investigation Design Storms Rainfall IDF Parameters Storm Distribution HYDROLOGIC ANALYSES Existing Drainage Conditions Surface Soil, Land Use, and Drainage Hydrologic Modelling Proposed Drainage Conditions Highway Improvements for Proposed Conditions Hydrologic Modelling and Discussion of Results HYDRAULIC ANALYSIS Proposed Conditions Hydraulic Analysis of Culvert STORMWATER MANAGEMENT Impact of the Proposed Roadway Improvements Proposed Stormwater Management Strategy Proposed Quantity Control Measures Proposed Quality Control Measures Proposed Erosion Control Measures Proposed Water Balance Measures CONCLUSIONS Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December ii

19 LIST OF TABLES Table 1: Rainfall IDF Data (City of Barrie Stormwater Management Guidelines) Table 2: Summary of Existing Conditions Hydrologic Modelling at Point of Interest Table 3: Comparison of Proposed (Ultimate) and Existing Conditions Flows Table 4: Hydraulic Analysis of Proposed Culvert Table 5: Volume to be Retained on Site for Water Balance LIST OF EXHIBITS Exhibit 1: Study Area... 5 Exhibit 2: Existing Conditions Drainage Mosaics Exhibit 3: Proposed Conditions Drainage Mosaics LIST OF APPENDICES APPENDIX A PHOTOGRAPHIC INVENTORY APPENDIX B CITY OF BARRIE IDF INFORMATION APPENDIX C HYDROLOGIC ASSESSMENTS APPENDIX D CULVERTS HYDRAULIC ASSESSMENTS APPENDIX E STORMWATER MANAGEMENT Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December iii

20 1.0 INTRODUCTION 1.1 Project Description and Purpose The City of Barrie (City) retained WSP MMM Group Limited (MMM) to undertake the Preliminary Design and Class Environmental Assessment (EA) Study for the improvements of the Highway Salem Road overpass crossing. The study area is shown in Exhibit 1. Salem Road is a paved rural road running east-west located west of Highway 400 and currently stops short of the highway at a dead end approximately 450m west the highway. Salem Road continues past the dead end as a private gravel road up to the Highway 400 right-of-way (ROW). Located to the east of Highway 400 is Lockhart Road which runs east-west aligned with Salem Road. Lockhart Road is a gravel rural road and stops at a dead end at the Highway 400 ROW. The proposed improvements at this crossing include the installation of an overpass connecting Salem Road to Lockhart Road over Highway 400, as well as urbanizing both roads within the study limits. The purpose of this Drainage and Stormwater Management Report is to document the traceable decisionmaking process undertaken in the preliminary design of the proposed overpass crossing and the stormwater management concept resulting from the proposed improvements to the Highway 400 Salem Road Crossing. Approval in principle from the relevant regulatory agencies is required for various aspects of the design. This Drainage and Stormwater Management Report documents existing drainage characteristics, issues related to drainage and stormwater management (SWM), hydrologic and hydraulic analyses, acceptable opening sizes of drainage structures, SWM strategy assessment, and recommendations for a feasible SWM system for the proposed works. 1.2 Proposed Works The proposed works include the following: Extension of Salem Road; Improvement of Salem Road to urban cross section; Improvement of Lockhart Road to urban cross section; Addition of Salem Road overpass to connect to Lockhart Road; Relocation of affected utilities; and Reconfiguration of existing drainage features and construction of new drainage features to accommodate the crossing improvements but maintaining existing drainage patterns. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

21 Exhibit 1: Study Area Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

22 1.3 Background Information MMM obtained and reviewed relevant information and mapping obtained from the City of Barrie, MTO, and Lake Simcoe Region Conservation Authority (LSRCA), including the following: Hydrologic Modelling - Hewitts, Sandy, Coe, Mooselnaka, Gilford, Lover s Creek and the City of Barrie Annexation Area, Final Report, Prepared for LSRCA by URS, dated July Subwatershed Impact Study, Salem Annexed Lands, City of Barrie, Schaeffers Consulting Engineers, July City of Barrie, Intensification and Annexed Lands Drainage and Stormwater Management Master Plan, Final Report, prepared by AMEC Environment and Infrastructure, dated October Lover s Creek Existing Subcatchment Plan, prepared by AMEC, dated October 2013 Drainage Memorandum Highway 400 /10 th Line (McKay Road) Underpass Replacement (Work Order ), prepared by AECOM for MTO, dated October 9, Highway 400 Preliminary Design Report, GWP , From 1 km south of Highway 89 northerly 30 km to the Junction at Highway 11, prepared by URS Canada Inc. for MTO, dated May Geotechnical Investigation, Salem Road Water Main Norris Drive to Lockhart Road, Barrie Ontario, prepared for AECOM by Peto MacCallum Ltd. dated August The City of Barrie, Storm Drainage and Stormwater Management Policies and Design Guidelines, dated November LSRCA Technical Guidelines for Stormwater Management Submissions, Draft, dated June MTO Highway Drainage Design Standards, dated Design Criteria and Standards The guidelines and policies used in the assessment of the drainage systems include: The City of Barrie, Storm Drainage and Stormwater Management Policies and Design Guidelines (2009); LSRCA Technical Guidelines for Stormwater Management Submissions (2016); MTO s Highway Drainage Design Standards (2008); and MTO s Drainage Management Manual (1997); The Ministry of the Environment and Climate Change s Stormwater Management Planning and Design Manual (MOE Manual, 2003) was also referenced in the assessment of the drainage system. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

23 The City of Barrie has prepared stormwater management criteria in a document Storm Drainage and Stormwater Management Policies and Design Guidelines. The sections that are relevant to this study are as follows: a) Stormwater Drainage System Policies and Design Guidelines: This section outlines the City s criteria for drainage systems such as storm sewers, overland flow routes, bridges and culverts, watercourses, etc. According to this: Flow from Road: Road grading must direct flows from the right-of-way to a safe outlet at specified low points. Outlets can be walkways or open sections of road leading to open spaces or river valleys. Roads may be used for major system overland flow conveyance during the Regulatory (i.e. the larger of the 100-yr storm or Hurricane Hazel) storm subject to the 0.10 m above crown of road for collector and industrial road and single lane remains to open for arterial roads. Overland Flow Channels: It shall be designed to convey the Regulatory Storm peak flow without flooding adjacent private properties. Appropriate stabilization shall be provided to protect against velocity conditions experienced during the Regulatory Storm and calculations shall be provided to the City for review and approval. The maximum velocities during the 1:5 year and Regulatory storms shall be 1.5 m/s and 2.5 m/s, respectively for sod lined channels. Bridges and Culverts: i. Culverts and bridges crossing arterial roads must be designed to prevent overtopping during the 100-yr storm. Under certain circumstances the City may request protection from overtopping for the Regional Storm. In addition, bridges and culverts shall be designed so there is no increase in the Regulatory flood conditions of the watercourse. ii. All culverts shall be supplied with headwall end protection constructed of interlocking wall systems, concrete, armour stone or other material approved by the City. Design Flow: Design flow for road crossings is the 100-year flow (or Hurricane Hazel, if directed by the city) for arterial roads and the 50-year flow for the collector roads. Erosion Protection: Armour stone, river stone and/or concrete shall be provided at all inlets and outlets to protect against erosion of the watercourse and provide embankment stability. The maximum allowable target channel velocity shall be in accordance with the MTO Drainage Management Manual. Water Course: Watercourses and associated flood plains shall be capable of handling the Regulatory flood run-off as determined by the Conservation Authority. b) Stormwater Management Policies and Design Guidelines: This section outlines the City s policies and design criteria for stormwater management measures design. This section includes guidelines such as: environmental protection, flood and erosion protection, site plans and infill developments, source and conveyance controls, end of pipe controls, stormwater management facilities for quality Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

24 and quantity control, stormwater management plantings, emerging technologies, and general maintenance requirements. c) Requirements for Erosion and Sediment Control during Construction: This section includes a list of required items to control erosion and sediment transport into natural watercourses during construction. d) Guidelines for Hydrologic and Hydraulic Analysis: This section includes analysis guidelines such as City of Barrie IDF data, preferred method for runoff and flow calculations, preferred methods for hydraulic calculations, and water balance criteria. Based on this: 1:2 year, 1:5 year, 1:10 year, 1:25 year, 1:50 year, 1:100 year and the Regional storms shall be applied for quantity control and the 25 mm 4-hour Chicago storm shall be applied for erosion control as required. In order to determine the critical design storms, the SCS Type II (6-hr, 12-hr and 24-hr durations) and the 4-hour Chicago storm distributions for the 1:2 year through 1:100 year return period shall be applied. Bridge and culvert calculations should be completed by computer programs such as CulvertMaster and HEC-RAS or SWMM. The LSRCA has prepared stormwater management criteria in a document LSRCA Technical Guidelines for Stormwater Management Submissions. This document outlines LSRCA requirements for stormwater management such as: a) Stormwater Quantity Control: This section outlines requirements for peak flow control, volume control, major-minor system, and Regulatory Storm conveyance. Based on this: Linear development on sites without restrictions that create 0.5 or greater hectares of new and/or fully reconstructed impervious surfaces, shall capture and retain / treat on site, the larger of the following: i. The runoff from a 12.5 mm event from the fully reconstructed impervious surface and newly constructed impervious area. ii. The runoff from a 25 mm event from the net increase in impervious area on the site. b) Stormwater Quality Control: This section outlines requirements for treatment of suspended solids, phosphorus, winter salt, temperature, and other contaminants. c) Stream Erosion Control: This section outlines requirements for onsite detention to reduce erosion potential on downstream receiving bodies. d) Water Balance/Groundwater Recharge: This section outlines requirements for maintaining predevelopment infiltration and evapotranspiration rates under proposed development conditions. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

25 e) Erosion and Sediment Control: This section outlines requirements for providing an effective erosion and sediment control plan during site disturbance activities. The MTO s Highway Drainage Design Standards prescribe standards for designing Surface Drainage Systems (SD) and Water Crossings (WC). The standards that are relevant to this study are as follows: a) SD-12 Freeboard above Adjacent Watercourse or Water Bodies: This standard identifies the minimum required freeboard for roadways that are constructed adjacent to watercourses or waterbodies. b) WC-2: Freeboard and Clearance at Bridge Crossings: This standard identifies the soffit clearance and freeboard for bridges over waterbodies. For the freeway, the soffit clearance and freeboard for the design storm should be 1.0 m or higher. A Desirable Freeboard is measured vertically from the Energy Grade Line elevation of the design flow to the edge of the travelled lane at the low point. This freeboard is a recommended value although it is recognized that, due to site-specific considerations, it is not always feasible to provide this amount. A Minimum Freeboard of 1.0 m measured vertically from the High Water Level of the design flow to the edge of the travelled lane at the low point. c) WC-7 Culvert Crossings on a Watercourse: This standard identifies the desirable and minimum freeboard, minimum clearance and the maximum flood depth at culvert crossings. The Flood Depth at Culverts with a rise less than 3.0 m should not exceed 1.5 times the diameter or rise of the culvert at the upstream face. For culverts with a rise between 3.0 m and 4.5 m the flood depth at the upstream face must not exceed 4.5 m. This standard applies to closed footing culverts and open footing culverts with non-erodible bottoms. d) WC-8 Minimum Culvert Size: This standard identifies the minimum culvert size based on maintenance considerations. The following design objectives were established to minimize the potential impacts of the proposed improvements on the surrounding environment, based on the prevailing policy framework: Provide an effective/efficient drainage system; Minimize risk to public safety; Maintain flow paths for upstream lands; Maintain or enhance the quality of storm runoff; Maintain or reduce flood risk for lands within and surrounding the transportation corridor; Impose not negative impact (i.e. no increase in peak flows) to the existing Highway 400 MTO culvert; Minimize future maintenance requirements; and Situate SWM measures on lands available in the transportation corridor. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

26 1.5 Site Investigation A field investigation was carried out in November The purpose of the site visit was to confirm the existing drainage conditions, local drainage patterns and drainage divides and conditions of any existing culverts. Site visit photographs are provided in Appendix A. 1.6 Design Storms Rainfall IDF Parameters Rainfall Intensity-Duration-Frequency (IDF) parameters for various return period design storms were obtained from the City of Barrie. The parameters, 4-hour, 6-hour, 12-hour, and 24-hour rainfall depths are summarized in Table Storm Distribution Hyetographs for 6-hour, 12-hour, and 24-hour duration storms are provided by the City in SCS storm distribution, and 4-hour in Chicago Storm distribution. The storm duration resulting in the highest peak flows and runoff volumes was used for the study. Storm distribution hyetographs as provided by the City are provided in Appendix B. Table 1: Rainfall IDF Data (City of Barrie Stormwater Management Guidelines) Parameter 2-year 5-year 10-year 25-year 50-year 100-year A B C Equation for Rainfall Intensity I = A/(t + B) C Rainfall Depth, mm (4 hour) Rainfall Depth, mm (6 hour) Rainfall Depth, mm (12 hour) Rainfall Depth, mm (24 hour) According to the Ministry of Natural Resources and Fisheries Flood Hazard Criteria Zones of Ontario, the project area falls within Zone 1. For this zone, the flood produced by the Hurricane Hazel storm is considered as the Regional Storm event. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

27 2.0 HYDROLOGIC ANALYSES 2.1 Existing Drainage Conditions This section discusses the existing soil, land use, drainage, and culverts of the study area. Hydrologic modelling was performed and the results are summarized in Section Surface Soil, Land Use, and Drainage The overall area is within the Lover s Creek watershed and slopes eastward toward Lake Simcoe. Soils within the drainage study limits are characterized primarily by sand with trace of gravel and loamy sand; however, there is also loamy sand present (geotechnical investigation performed by Peto MacCallum, August 2009). The study area drains to the south of Salem Road to a tributary of Lover s Creek approximately 600 m south of the study area. This tributary flows easterly through a culvert under Highway 400. Land use in this area includes paved road and parking lot, gravel road, and grassed fields. The existing drainage mosaic is shown in Exhibit 2. The existing drainage mosaic shows the existing catchments for the Highway 400 Salem Road crossing and surrounding area. Under existing conditions, the roadway runoff is conveyed by roadside ditches. On the west side of Highway 400, runoff from Catchment 200 drains to the sag of the existing gravel road section of Salem Road approximately 130 m west of the Highway 400 ROW. Runoff from Catchments 205 and 210 drain to the Salem Road roadside ditches from the north side of the roadway and combines with flows from Catchment 200. Runoff from Catchment 215 drains toward the roadway sag from the west side ditch of the road and runoff from Catchment 220 drains southerly. The combined flows from all these catchments (from Catchments 200 to 220) drain south-easterly to the Lover s Creek tributary and are conveyed through the Highway 400 culvert. On the east side of Highway 400, runoff from Catchments 225 and 230 drain southerly overland to the Lover s Creek tributary. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

28 LEGEND: CATCHMENT BOUNDARY C1 CATCHMENT No ha CATCHMENT AREA DIRECTION OF FLOW ha 210 SAUNDERS ROAD 0.25ha LOCKHART ROAD STUDY LIMIT VETRANS DRIVE ha ha ha SALEM ROAD HIGHWAY 400 LOVER'S CREEK TRIBUTARY ha STUDY LIMIT EXISTING CONDITIONS DRAINAGE MOSAIC HWY SALEM ROAD CROSSING EXHIBIT 2

29 2.1.2 Hydrologic Modelling The purpose of hydrologic modelling is to simulate the hydrologic response of the areas draining to various points of interest in the study area for various return period rainfall events. The hydrologic event simulation modelling software Visual OTTHYMO 2.4 (V02) used because the software: Was developed and tested in Ontario; Allows single event modelling of user defined design storms; Generates flow hydrographs at user specified locations (points of interest); Considers varying soil and land use conditions; and Allows channel and reservoir routing. The methodology used to develop the hydrologic model can be summarized as follows: Drainage area boundaries were delineated using the latest contour maps. Modelling parameters were estimated for each catchment based on the delineated drainage area, land use distribution (obtained from topographic mapping and aerial photo), soils distribution, and slopes of the overland and channel flow paths; The hydrologic response for drainage areas with a directly connected impervious land use greater than 20 percent was simulated using the Standard instantaneous unit hydrograph (STANDHYD); The hydrologic response for drainage areas with a directly connected impervious land use less than 20 percent was simulated using the Nash instantaneous unit hydrograph (NASHHYD); and Runoff hydrographs were generated at key points of interest including at the outlet of the study limits. The hydrologic modelling input parameters for each drainage area and V02 output summaries are included in Appendix C. Table 3 summarizes the results of the existing conditions hydrologic modelling for the 2-year to the 100-year storm events based on the 6-hour SCS, 12-hour SCS, 24-hour SCS, and 4-hour Chicago storm distributions. As shown, the flows obtained from the 6-hour SCS storm distribution are the highest at most of the points of interest. Therefore, the peak flows obtained from the 6-hour SCS storm distribution are selected for used in the hydraulic modelling presented in Section 3.2. However, the 24-hour SCS storm distribution was used in the assessments and design of SWM facilities. The 24-hour SCS storm produces the highest volumes. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

30 Table 2: Summary of Existing Conditions Hydrologic Modelling at Point of Interest Flow Location/ Point of Interest Upstream of Salem Road Sag North Side Salem Road West of Culvert North Side Salem Road east of Culvert South Side Salem Road West of Culvert South Side Salem Road east of Culvert Combined Flow of Study Area West of HWY 400 Hydro ID Storm Distribution Flow (m3/s) 2-Yr 5-Yr 10-Yr 25-Yr 50-Yr 100-Yr Regional 4-hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II North Side Salem Road East hr Chicago hr SCS II hr SCS II hr SCS II South Side Salem Road East Combined Flow of Lockhart Road East of HWY hr Chicago hr SCS II hr SCS II hr SCS II hr Chicago hr SCS II hr SCS II hr SCS II Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

31 2.2 Proposed Drainage Conditions This section discusses the proposed drainage improvements and patterns resulting from the improvements to the highway crossing (Section 2.2.1). Hydrologic modelling was carried out using Visual OTTHYMO 2.4 (V02) and the results are summarized in Section Highway Improvements for Proposed Conditions Under proposed conditions: Salem Road and Lockhart Road will be widened; Salem Road and Lockhart Road will be urbanized (with curb and gutter, and sidewalks/multi-use paths); and Salem Road and Lockhart Road will be connected by an overpass over Highway 400. Exhibit 3 shows the proposed conditions drainage mosaic which illustrates the proposed catchments based on the improvements to the Salem Road and overpass crossing of Highway 400. On the west side of Highway 400, Catchment 200 will drain to a proposed new culvert under Salem Road at approximately Station where the sag currently exists. Catchment 200 will remain unchanged as in existing conditions. Runoff from urban roadway Catchment 205 will be conveyed by storm sewers and will be directed to a dry SWM facility located in Catchment 225 for runoff quantity control. Outflows from the pond will discharge to the downstream side of the proposed culvert. Runoff from Catchment 210 will be conveyed by storm sewers and a pipe storage facility (Super pipe) will be used for peak flow control. The outflows from the pipe storage facility will discharge to the downstream side of the culvert. Catchment 220 includes half of the proposed Highway 400 overpass; runoff from Catchment 220 will be conveyed by storm sewers and will be discharged uncontrolled to the downstream side of the proposed culvert. Due to over controls provided at the dry SWM facility in Catchment 225, peak flow controls for runoff from Catchment 220 are not required. The combined flows from Catchments 200 to 220 eventually drain south-easterly to the Lover s Creek tributary toward the Highway 400 culvert. On the east side of Highway 400, Catchment 230 will drain via storm sewers under Lockhart Road which will either outlet into a drainage swale or be connected to storm sewers under Lockhart Road designed by others (beyond MMM s study limit). Since the stormwater management works of Lockhart Road (beyond the study limit) is unknown at the time of preparing the Report, MMM has proposed a storage pipe facility for runoff peak flow control for the potion of Lockhart Road from the Highway 400 overpass to the easterly study limit. Should be situation be known in the near future, for example a SWM facility or storage facility, this proposed pipe storage facility can be removed from the current design. Oil and grit separators (OGS) will be provided for the roadway Catchments 205, 210, 220 and 230 for the runoff quality treatment. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

32 LEGEND: CATCHMENT BOUNDARY C1 CATCHMENT No ha CATCHMENT AREA DIRECTION OF FLOW ENHANCED GRASSED SWALE OIL GRIT SEPARATOR ha SUPER PIPES 100-YR STORAGE VOLUME = 390 m³ PROPOSED CULVERT 1520 mm X 910 mm CONCRETE BOX HIGHWAY 400 PROPOSED 34.0 m ROW LOCKHART ROAD PROPOSED 34.0 m ROW SAUNDERS ROAD VETRANS DRIVE ha ha EXFILTRATION TRENCH FOR WATER BALANCE ha LOCKHART ROAD SAUNDERS ROAD EXFILTRATION TRENCH FOR WATER BALANCE ha PROPOSED 34.0 m ROW SALEM ROAD 225 INFILTRATION GALLERY FOR WATER BALANCE SUPER PIPE 100-YR STORAGE VOLUME = 250 m³ HIGHWAY ha DRYSWM FACILITY 100-YR STORAGE VOLUME = 1840 m³ LOVER'S CREEK TRIBUTARY STUDY LIMIT PROPOSED CONDITIONS DRAINAGE MOSAIC HWY SALEM ROAD CROSSING EXHIBIT 3

33 2.2.2 Hydrologic Modelling and Discussion of Results As determined in Section 2.1.2, the 6-hour SCS Type II storm distribution resulted in the highest flows compared to the 12-hour and 24-hour SCS and 4-hour Chicago storm distributions at most of the points of interest. Therefore, the proposed conditions hydrologic modelling was carried out using the 6-hour SCS Type II storm distribution. Hydrologic modelling was completed to simulate both uncontrolled and controlled drainage conditions following the proposed highway crossing improvements. Table 3 provides a comparison of the existing and proposed conditions flows. Table 3: Comparison of Proposed (Ultimate) and Existing Conditions Flows Outlet Hydro ID Drainage Area (ha) Condition 6-hour SCS Storm Distribution Flows (m 3 /s) 2-yr 5-yr 10-yr 25-yr 50-yr 100-yr Regional Flow to Lover s Creek Tributary from Study Area, west of Highway 400, Existing Pr. Un Difference (Pr. Un. Ex) % Increase 39.2% 35.5% 31.1% 28.4% 25.3% 23.8% 4.3% Pr. Co Difference (Pr. Co. Ex) % Increase -2.0% -4.2% -5.7% -6.6% -6.6% -6.8% -8.2% Existing Combined Flow of Study Area, east of Highway / Pr. Un Difference (Pr. Un. Ex) % Increase 1030% 575% 471% 363% 319% 283% 14% Pr. Co Difference (Pr. Co. Ex) % Increase 0.0% -12.5% -8.8% -9.8% -17.2% -24.4% -24.5% Note: Pr. Un. = Proposed Uncontrolled Pr. Co. = Proposed Controlled Ex = Existing d/s = Downstream As shown in Table 3, the 2-year to the 100-year flows at the downstream side of the proposed culvert increase from m 3 /s to m 3 /s for the 2-year storm to m 3 /s to m 3 /s for the 100-year storm, respectively. Two SWM facilities consisting of a dry pond and a super pipe are proposed to control flows from Catchment 205 and 210, respectively before discharging overland to the Lover s Creek Tributary. The dry pond is in Catchment 225, and runoff from Catchment 205 and the pond catchment will be over-controlled to compensate the uncontrolled flows from Catchments 220 and 200. Flows from Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

34 Catchments 220 and 200 will be discharged uncontrolled. The resulting total controlled runoff rates to the Lover s Creek tributary under proposed conditions will be less than existing conditions. On the east side of Highway 400, the 2-year to the 100-year flows draining from Lockhart Road within the study limits increase from m 3 /s to m 3 /s for the 2 year storm to m 3 /s to m 3 /s for the 100-year storm, respectively. Runoff from this section of the road will be controlled with oversized pipe (super pipes) storage facility. The resulting total controlled runoff release rates from this section of the road will be less than the existing runoff rates, as summarized in Table 3. The proposed conditions hydrologic input parameters, V02 schematics, input data and summary of output files for all modelling scenarios are provided in Appendix C. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

35 3.0 HYDRAULIC ANALYSIS The Bentley s CulvertMaster hydraulic modelling software was used to design the proposed culvert under Salem Road at the existing sag location. The design standards for the hydraulic assessment of culverts and bridges are based on the MTO Highway Drainage Design Standards (HDDS) (February 2008) which was discussed in Section 1.3. The CulvertMaster model was used to estimate the headwater depth and to assess the hydraulic capacity of the proposed culvert. The CulvertMaster model was selected for the following reasons: Evaluates inlet and outlet controlled headwater depths; Simulates the hydraulic performance of culverts based on user-specified flows; Considers variable tailwater depths based on either outlet channel geometry or user specified depth discharge rating curves; and Incorporates an extensive database of standard culvert sizes, shapes and materials, and allows for the addition of custom culvert types and sizes. Under existing conditions, there is no culvert under Salem Road; instead less frequent return period storm flows could overtop the gravel road at the sag. 3.1 Proposed Conditions Hydraulic Analysis of Culvert Salem Road will be classified as urban arterial road under proposed conditions. The design flow for the proposed culvert will be the 50-year flow with no overtopping for the 100-year flow. It was determined that a 1520 mm span x 910 mm rise concrete box culvert will meet both the City of Barrie and MTO design criteria. The proposed culvert size will provide a desirable freeboard above the energy grade line greater than 1 m, a HW/D ratio less than 1.5, and no overtopping for any design storm event. The slope of the existing ground is more than 10%. In order to maintain a small slope for the culvert to minimize velocities, the upstream inlet will require a drop channel design or an inlet structure, which will be carried out during the detail design phase. Table 4 provides the details of the hydraulic analysis of the proposed culvert. Rock protection or an outlet pool with a flow spreader may be required at the outlet of the culvert for erosion protection and energy dissipation. The CulvertMaster output reports for the 50-year, 100-year, and Regional design storms are included in Appendix D. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

36 Table 4: Hydraulic Analysis of Proposed Culvert Culvert ID Size (mm) / Type Length (m) U/s Invert (m) D/s Invert (m) EOP Elev. at Low Point / Spill Elev. (m) Events Flow (m 3 /s) Computed HWL (m) Exit Velocity (m/s) Upstream Velocity Head (m) EGL (m) Desired Freeboard (m) HW/D Meets requirements? C mm x 910 mm Concrete Box year year Regional For Design Storm: Freeboard > 1m Yes HW/D 1.5 Yes For 100-year and Regional Storm: No Overtopping Yes Notes: U/s - Upstream * Desirable freeboard obtained from subtracting EOP elevation at low point and EGL elevation. D/s - Downstream EOP - Edge of pavement HWL - Headwater Elevation EGL - Energy Grade Line HW/D - Headwater over Depth Ratio Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

37 4.0 STORMWATER MANAGEMENT This section documents the preliminary screening of SWM practices, the increase in pavement area due to the roadway widening, an assessment of potential impacts, and the proposed SWM facilities to overcome the impacts. Under existing conditions, Salem Road and Lockhart Road are rural roads with roadside ditches to convey storm runoff. Under proposed conditions, both Salem Road and Lockhart Road will be widened to four (4) lanes and urbanized with a center median and curb and gutter. In order to meet the criteria as discussed in Section 1.4, a number of mitigation measures are recommended including a dry pond, Enhanced grassed swale, oversized pipes for storage (super pipes), exfiltration trenches, infiltration galleries, and oil and grit separator (OGS) units. 4.1 Impact of the Proposed Roadway Improvements The Salem Road and Lockhart Road widening will lead to an increase in impervious areas within the Lover s Creek watershed. The roadway impervious area (Catchments 205 to 220) on the Salem Road section (west side of Highway 400) increased from 19% to 79%. As a result of this, the overall imperviousness, including the external Catchment 200, increased from 27% to 39%. The roadway impervious area (Catchments 225 to 230) on the Lockhart Road section (east side of Highway 400) increased from 18% to 80%. As a result of the increase in imperviousness, flow increases at the point of interest are as presented in Table 3. The key observations at the points of interest are: The flows draining to Lover`s Creek tributary increased by m 3 /s (42%) for the 2-year to m 3 /s (25%) for the 100-year, respectively. The flows from the Lockhart Road section increased by m 3 /s (1030%) for the 2-year to m 3 /s (283%) for the 100-year, respectively. Hence, peak flow controls are required to control the flows from post- to pre-development levels. 4.2 Proposed Stormwater Management Strategy The four (4) primary criteria that the SWM strategy must meet are: 1. Quantity Control (no increase in runoff peak flow rates); 2. Quality Control (provide treatment measures to remove contaminants from the runoff); 3. Erosion Control measures; and 4. Volume Control (retain a specified volume of runoff on site) for water balance. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

38 4.2.1 Proposed Quantity Control Measures In order to meet the quantity control criterion for Salem Road, the following measures are proposed: A dry pond is recommended in Catchment 225 to control runoff from Catchment 205. The maximum size of the dry pond would be approximately 1840 m 3 in volume based on the 100-year 24-hr SCS storm. The pond will control the 2-year to the 100-year flows to less than pre-development levels. The pond will provide over control of flows to balance the uncontrolled flows from Catchment 210. A super pipe is proposed in Catchment 210. The maximum volume required to control the flows to predevelopment levels is 250 m 3. A 70 m long, 2400 mm x 1500 mm concrete box pipe will be required which will give a storage volume of 252 m 3. The outflows from the storm sewer will be directed to the downstream side of the proposed culvert. As mentioned above, no control will be provided for Catchment 210. The outflows from the storm sewer will be directed to the downstream side of the proposed culvert. On the east side of Highway 400, a super pipe is proposed in Catchment 230. The maximum volume required to control the flows to pre-development levels is 390 m 3. A 110 m long, 2400 mm x 1500 mm concrete box pipe will be required which will give a storage volume of 396 m 3. As mentioned in Section 2.2.1, should the SWM situation of Lockhart Road be known in the near future, for example a SWM facility or storage facility designed at another location, this proposed pipe storage facility can be removed from the current design. Exhibit 3 includes the recommended measures for peak flow controls. Stage-discharge-storage calculations are provided in Appendix E Proposed Quality Control Measures Under proposed conditions, quality control measures will be provided through the use of Enhanced grassed swales wherever feasible, OGS units, and CB Shields. CB Shields prevent stormwater inflow from disturbing the catchbasin sump and re-suspending solids and it can be installed in those catchbasins where the storm sewer cannot be directed to Enhanced grassed swales. This technology is Environmental Technology Verification (ETV) verified to capture 50% TSS and can be fitted with an oil capture device if required. OGS units are recommended to be used in combination with the Enhanced grassed swales or CB Shields to maintain the treatment train. OGS units provide up to 50% of TSS removal when used as part of a treatment train. The following are recommended for quality control measures: From Station to Station of Catchment 205, road runoff which will be conveyed by storm sewer and will discharge to an Enhanced grassed swale on the south of the roadway. An OGS will be provided before discharging to the Enhanced grassed swale (EGS). The minimum bottom width of the Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

39 EGS will be 1.0 m with 3:1 side slope. The length will be approximately 50 m. The EGS will convey runoff to the dry SWM facility. For the remaining section of the road from Station to 0+760, storm runoff will be treated by an OGS. A measure of treatment can also be achieved in the dry SWM facility. The combination of OGS, Enhanced grassed swale and SWM facility will maintain the treatment train approach. The outflows from the SWM facility will be directed to vegetative landscape through the use of a flow spreader. The overland sheet flow through vegetative landscape further provides a measure of quality treatment. For Catchments 210 and 220, a combination of CB Shields) and OGS will be provided to maintain the treatment train approach. CB Shields will be provided for each catchbasin of the roadway and the treated runoff will be conveyed by storm sewer to an OGS. The OGS will provide additional treatment before discharging to Lover s Creek tributary. Similarly, for Catchment 230, a combination of CB Shields and OGS will be provided to maintain the treatment train approach. CB Shields will be provided for each catchbasin of the roadway and the treated runoff will be conveyed by storm sewer to an OGS. The OGS will provide additional treatment before discharging downstream on Lockhart Road. As mention in Section 2.2.1, should the SWM situation of Lockhart Road be known in the near future, for example a SWM facility or storage facility designed at another location, the proposed CB Shields and OGS can be removed from the current design. Exhibit 3 also includes the recommended measures for quality control Proposed Erosion Control Measures Under proposed conditions, there will be several storm sewer outfalls (including the dry pond outfall). If discharged directly to grade, the concentrated flows from the outfalls have potential to cause erosion and scour. In order to mitigate this erosion potential, outlet pools and dispersion berms (flow spreader) will be designed at these outlets. The plunge pools will provide energy absorption and velocity control, while the dispersion berm will allow for the concentrated flows to disperse evenly into sheet flow. Evenly distributed sheet flow has much less erosion potential than the highly concentrated flows from the storm sewers. Based on this concept, the following are recommended: An outlet pool to be provided at the storm sewer outlet on the south side at Station to provide any potential erosion on the Enhanced grassed swale. A rock protection to be provided at the end of the Enhanced grassed swale to protect any embankment erosion of the SWM pond. A flow spreader to be provided at the pond outlet to disperse concentrated flows from the outlet pipe to sheet flows. An outlet pool with rock protection to be provided on the downstream end of the proposed culvert to protect channel bed erosion. Typical schematics of these erosion control measures are shown in Exhibit 3. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

40 4.2.4 Proposed Water Balance Measures The LSRCA criteria state that for linear development volume control, the volume to be retained on site for water balance is the larger of the following: a) The runoff from a 12.5 mm event from the fully reconstructed impervious area, or b) The runoff from a 25 mm event from the net increase in impervious area on the site. Table 5 provides the summary of retention volumes required to provide for water balance on site. Table 5: Volume to be Retained on Site for Water Balance Salem Road Criteria 12.5 mm from the fully reconstructed impervious area 25 mm from net increase in imperious area Lockhart Road 12.5 mm from the fully reconstructed impervious area 25 mm from net increase in imperious area Total Roadway Area (ha) Fully Reconstructed Impervious Area (ha) Retention Volume Based on Net Increase in Impervious Area (ha) Retention Volume (m 3 ) Recommended Retention Volume (m 3 ) From the above table, the governing volumes for water balance retention are based on the 25mm event from the net increase in impervious area on the site. On site water balance retention volume can be achieved through infiltration gallery and exfiltration trench on Salem Road and exfiltration trench on Lockhart Road. An infiltration gallery will be provided within the dry SWM facility providing approximately 480 m 3 of retention volume. An exfiltration trench with approximate retention volume of 80 m 3 will be provided in Catchment 210. An exfiltration trench with approximate retention volume of 120 m 3 will be provided in Catchment 230. To determine the sizing of the exfiltration and infiltration trenches, the MOECC guideline equations 4.2 Maximum Allowable Soakaway Pit Depth and 4.3 Infiltration Trench Bottom Area were used: According to Equation 4.2: According to Equation 4.3: d = PT 1000 A = 1000V/(P n T) = V d. n Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

41 Where, A = bottom area of the trench (m 2 ) d = maximum allowable depth of the soakaway pit (m) V = runoff volume to be infiltrated P = percolation rate of surrounding native soil (mm/hr) n = porosity of the storage media (0.40 for clear stone) T = retention time or drawdown time (48 hrs for this site). From the MOECC guidelines Table 4.4: Minimum Soil Percolation Rates it can be seen that percolation rates for sand, loamy sand, and sandy loam are 210, 60, and 25 mm/hr respectively. As this site is primarily a mixture of sand and loamy sand, the percolation rate will be assumed to be 100 mm/hr for preliminary design. A percolation test of the soil is recommended during the detail design phase. A safety correction factor of 2.0 will also be applied in order to account for soil compaction during construction, as well as long term loading. This safety correction factor will reduce the design percolation rate to 50 mm/hr. Based on the volume requirement provided above, A 50 m long x 14 m wide x 1.8 m high infiltration gallery will be provided within dry SWM facility. It provides 504 m 3 of storage volume for water balance. A 75 m long x 1.5 m wide x 1.8 m high exfiltration trench will be provided at Salem Road Catchment 220 west of Highway 400. This will provide 81 m 3 of storage volume for water balance. A 95 m long x 1.8 m wide x 1.8 m high exfiltration trench will be provided at Lockhart Road Catchment 230 east of Highway 400. This will provide 123 m 3 of storage volume for water balance. The calculations for the sizing of infiltration gallery and exfiltration trenches are provided in Appendix E. The ultimate configuration of exfiltration trenches and infiltration gallery will be determined during the detail design stage; however, the analysis above indicates that the required volume can be retained and infiltrated on site to meet LSRCA criteria. Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

42 5.0 CONCLUSIONS Based on the preceding analyses for the proposed Salem Road crossing over Highway 400, the following conclusions can be made: 1. The existing drainage systems consist exclusively of open roadside ditches. 2. The proposed improvements and road widening will increase impervious areas, resulting in increased stormwater runoff. 3. Under proposed conditions: A 1520 mm span x 914 mm rise concrete box culvert is proposed to convey the runoff from the external area north of Salem Road to Lover s Creel tributary to maintain the drainage pattern. The proposed Salem Road and Lockhart Road widening will lead to an increase in impervious areas within the Lover s Creek watershed. The roadway impervious area on the Salem Road section west of Highway 400 increased from 19% to 79%. The roadway impervious area on the Lockhart Road section east of Highway 400 increased from 18% to 80%. Therefore, peak flow controls are required to control the flows from post- to pre-development levels. Stormwater runoff peak flows will be controlled on Salem Road through the use of a dry pond and super pipes and on Lockhart Road through the use of super pipes. On site stormwater retention will be provided through the utilization of exfiltration trenches below the storm sewers, and an infiltration gallery below the dry pond. Stormwater quality treatment will be provided through the use of CB Shields, OGSs, and Enhanced grassed swales. Under proposed conditions, these recommendations will meet the established criteria and mitigate the potential negative impact that can be caused by the increase in pervious areas. All of which is respectfully submitted by: MMM Group Limited Madhav Baral, M.A.Sc., P. Eng. Senior Project Engineer Peter Lim, P. Eng. Senior Project Manager Drainage and Stormwater Management Report Salem Road Crossing at Highway 400 MMM Group Limited December

43 APPENDIX A PHOTOGRAPHIC INVENTORY

44 PHOTOGRAPHIC INVENTORY Salem Road Crossing at Highway 400, City of Barrie APPENDIX A Photo 1: Salem Road looking east Photo 2: Salem Road looking east toward low point (sag) Photo 3: Salem road looking east toward road low point Photo 4: Salem Road, south side of road low point 1 of 2

45 PHOTOGRAPHIC INVENTORY Salem Road Crossing at Highway 400, City of Barrie APPENDIX A Photo 5: Downstream Channel looking south from Salem Road low point Photo 6: Lockhart road looking east from Cul-de-sac Photo 7: Looking south from Lockhart Road Cul-de-sac. Photo 8: Looking north east from Lockhart Road Cul-de-sac. 2 of 2

46 APPENDIX B CITY OF BARRIE IDF INFORMATION

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