Harmony Road (Regional Road 33) Class Environmental Assessment Rossland Road (Regional Road 28) To Conlin Road. Stormwater Management Report

Harmony Road (Regional Road 33) Class Environmental Assessment Rossland Road (Regional Road 28) To Conlin Road Stormwater Management Report PREPARED ...
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Harmony Road (Regional Road 33) Class Environmental Assessment Rossland Road (Regional Road 28) To Conlin Road Stormwater Management Report

PREPARED FOR: Regional Municipality of Durham 605 Rossland Road East Whitby, Ontario L1N 6A3 PREPARED BY: Stantec Consulting Ltd. 300-675 Cochrane Drive Markham, Ontario L3R 0B8

Date: May 2011 Project Number: 160210516

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

Table of Contents 1.0 INTRODUCTION ..............................................................................................................1.1 1.1 STUDY PURPOSE .................................................................................................1.1 1.2 BACKGROUND INFORMATION ............................................................................1.2 2.0 EXISTING CONDITIONS ..................................................................................................2.4 2.1 HARMONY ROAD STORM DRAINAGE .................................................................2.4 2.1.1 Minor System .....................................................................................................2.4 2.1.2 Major System .....................................................................................................2.8 2.1.3 Stormwater Management ...................................................................................2.8 2.2 HARMONY CREEK FLOODPLAIN.........................................................................2.8 3.0 STORMWATER MANAGEMENT DESIGN CRITERIA ...................................................3.10 3.1 WATER QUALITY CONTROL ..............................................................................3.10 3.2 WATER QUANTITY CONTROL ...........................................................................3.10 3.3 EROSION & SEDIMENT CONTROL ....................................................................3.11 4.0 ALTERNATIVE DESIGNS ..............................................................................................4.12 5.0 MITIGATION MEASURES ..............................................................................................5.13 5.1 STORMWATER MANAGEMENT .........................................................................5.13 5.1.1 Water Quality Control .......................................................................................5.14 5.1.2 Water Quantity Control .....................................................................................5.16 5.1.3 Erosion & Sediment Control .............................................................................5.17 6.0 STORM SEWER CAPACITY ASSESSMENT.................................................................6.18 7.0 CONCLUSION ................................................................................................................7.20

APPENDIX A APPENDIX B APPENDIX C APPENDIX D

STORMSEWER CAPACITY ASSESSMENT AND HYDROLOGIC CALCULATIONS STORMSEWER INSPECTION CCTV REPORT SUMMARY TAUNTON COMMUNITY SWM MASTER PLAN: DRAWING CS-1 CLOCA CORRESPONDENCE

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

List of Tables Page

TABLE 5.1

SURFACE DRAINAGE OUTLET CHARACTERISTICS

5.13

TABLE 6.1

STORMSEWER OUTLET CAPACITY ASSESSMENT SUMMARY

6.18

List of Figures Page

FIGURE 1

STUDY AREA

1.1

FIGURE 2a

STORM DRAINAGE

2.5

FIGURE 2b

STORM DRAINAGE

2.6

FIGURE 2c

STORM DRAINAGE

2.7

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

1.0

Introduction

1.1

STUDY PURPOSE

The Regional Municipality of Durham (Region) retained Stantec Consulting Ltd. (Stantec) to undertake a Class Environmental Assessment (Class EA) Study for modifications to Harmony Road (Regional Road 33). The Study Area for the Harmony Road Class EA extends from Rossland Road (Regional Road 28) to Conlin Road as shown in Figure 1 below.

N

Figure 1 - Study Area The Durham Regional Official Plan (ROP) designates Harmony Road as a Type A arterial road, which is the highest classification for arterial roads and reflects its importance in the Regional transportation system. In the Region’s current Transportation Master Plan (TMP) as adopted in 2003 and updated in 2005, the subject section of Harmony Road was identified for widening from three to five lanes between Rossland Road and Taunton Road and from two to four lanes between Taunton Road and Conlin Road. The current EA study builds upon the recommendations of the TMP, and is intended to confirm the opportunities and constraints associated with modifying Harmony Road, engage the public in discussing and reviewing the issues, and address the details of implementation of the recommended project. The overall intent of the Class EA is to improve the safety and efficiency of Harmony Road between Rossland Road and Conlin Road in order to accommodate anticipated increases in V:\01602\active\160210516 - Harmony Road Class EA\SWM\rpt_Final_SWM_Report_May_2011.doc

1.1

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT travel demands while facilitating and achieving social-economic and natural environment benefits for this area of the City of Oshawa and for the Region as a whole. This Stormwater Management (SWM) Report documents the existing drainage and floodplain conditions through the Study Area, evaluates the relative impacts of the alternative solutions on the receiving surface water systems, and recommends measures to mitigate the impacts of the preferred alternative.

1.2

BACKGROUND INFORMATION

The following sources have been referenced during the preparation of this SWM analysis: •

Black, Harmony, and Farewell Creeks Floodplain Mapping Study (Final Report), prepared by Aquafor Beech Limited, June 21, 2010;



Low Impact Development Stormwater Management Planning and Design Guide, Toronto and Region Conservation Authority, (2010);



Design and Construction Specifications for Regional Services, Regional Municipality of Durham (Works Department), April 2010;



Black, Harmony, Farewell Creek Watershed Existing Conditions Final Report, Central Lake Ontario Conservation, April 2011. Available for download at the following website: http://www.cloca.com/resources/Watershed_Man_Plans/Black_Harmony_Farwell_Watershe d_Management_Plan_2011/index.html



Engineering Design Standards & Criteria (Revision No. 8), City of Oshawa, dated May 2008;



Coldstream Drive - Stormsewer Design Sheet & Drainage Area Plan, City of Oshawa, dated August 2007;



Stormwater Management Brief – Proposed Oshawa North Commercial Development (Smart Centres), Counterpoint Engineering Inc, dated April 2007 (revised June 2007);



Harmony Horizons (Phase 3) Storm Sewer Drainage Plan and Calculations, D.G. Biddle & Associates Ltd., January 16, 2006;



Dusty Dawn Residential Development (18T-043230: Proposed Conditions Drainage Area Plan and SWM Pond Calculations, Sernas Associates, June – August, 2005;



Harmony Road As-Constructed Plan/Profile Drawings R-1 through R-3 (North of Taunton Road), Regional Municipality of Durham, February 2005;



Stormwater Management Plan - New Oshawa Recreation Complex – Part of Lot 4, Concession 4, D.G. Biddle & Associates Limited, March 26, 2004;



Harmony Horizons Storm Sewer Drainage Plan and Calculations, D.G. Biddle & Associates, Ltd., November 24, 2000;

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT •

Stormwater Management Master Plan: Taunton Community, Harmony Creek, City of Oshawa; Gartner Lee, Malone Given Parsons, Nak Design Group, Terraprobe, and Sernas Associates, dated August, 1997 (revised October 2004);



Harmony Road As-Constructed Plan/Profile Drawings 0-84-R-319 through 0-84-R-321 (South of Taunton Road), Regional Municipality of Durham, August 1985;



Harmony Road As-Constructed Plan/Profile Drawings 0-84-R-298 through 0-84-R-303 (South of Taunton Road), Regional Municipality of Durham, November 1985;



Stormwater Management Planning and Design Manual (SWMPD Manual), Ontario Ministry of the Environment, dated March 2003;



Design Specifications for Stormsewers, Regional Municipality of Durham Works Department, dated October 2002;



Taunton Road Reconstruction – MOE Application and Support, Sanchez Engineering Inc., May, 2000; and



Aerial Photography, Regional Topography, and other Planimetric Information provided by the Region of Durham, 2010.

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

2.0

Existing Conditions

The Study Area is predominantly located within the Harmony Creek Watershed. In the northernmost extent of the Study Area, Harmony Road straddles the drainage divide between the Harmony Creek Watershed (to the east) and the Oshawa Creek Watershed (to the west). The proposed improvements to Conlin Road, west of its intersection with Harmony Road, is located within the Oshawa Creek Watershed.

2.1

HARMONY ROAD STORM DRAINAGE

2.1.1

Minor System

The minor system flow is generally described as the stormwater runoff that conveys flow through a stormsewer and/or roadside ditch collection systems. Minor drainage system for the Region of Durham currently requires that all new stormsewer be designed to convey the 10-year storm unless outletting into an existing stormsewer system, in which case a 5-year design storm may be considered for design. The City of Oshawa has traditionally designed stormsewer to accommodate rainfall events up to and including the 1-year storm. Capacity of existing systems have been assessed with consideration for the preferred alternative as part of this study and conclusions have been drawn regarding the system’s ability to accept additional roadway runoff anticipated as part of the widening and/or provide recommendations for system capacity upgrades. The southern portion of the Study Area is serviced by stormsewer, which extends from the southern study limit (just north of Rossland Road) north to Taunton Road. Aside from a small portion of stormsewer that exists along the east side of Harmony Road from Taunton Road to just south of Coldstream Drive, roadside drainage ditches collect surface runoff for the portion of the Study Area located north of Taunton Road. Roadside ditches are crossed by the occasional cross culvert underneath adjacent municipal roads and private driveway entrances. From a point approximately 580 m south of Conlin Road (Station 3+420), which is the highest point along the existing roadway profile through the Study Area, roadway drainage generally runs in a direction from north to south for approximately 2,960 m until the existing bridge crossing over the main branch of Harmony Creek. This bridge constitutes the only major watercourse crossing throughout the Study Area. Roadway drainage between the above referenced high point and the existing bridge crossing discharge stormwater at several separate stormsewer outlet locations along Harmony Road (refer to Figure 2a through Figure 2c). Please refer to the roadway plan/profile drawings for the stationing/alignment. Surface drainage for areas north of the above referenced high point is collected via roadside ditches with runoff discharging overland into open drainage swales or overland relief areas at four (4) separate ditch outlet locations along Conlin Road (refer to Figure 2a). Roadway drainage from Harmony Road is currently partially treated by three (3) existing Stormwater Management (SWM) ponds. Drainage areas H5, H7, and H8 currently drain to the Harmony Horizons subdivision wet SWM pond, Dusty Dawn subdivision wet SWM pond, and the Smart Centres wet SWM pond, respectively (refer to Figure 2b).

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT Aside from the open roadside drainage swales (ditches) through the northern vicinity (rural roadway section) of the Study Area, there does not appear to be any formal SWM measures currently within the right-of-way to control the quantity or quality of storm runoff from Harmony Road. 2.1.2

Major System

Major system flow is the overland flow that drains towards a receiving watercourse above the capacity of the minor system. Harmony Road itself is the primary major system conveyance route through the Study Area. Major system flows drain overland in accordance with the existing roadway profile. Along the northern portion of the Study Area, major system drainage is provided within the roadside ditches since this portion of the roadway is not confined by curb and gutter. 2.1.3

Stormwater Management

Based on the Black/Harmony/Farewell Creek Watershed Existing Conditions Report, dated April 2011, there are nearby existing water quantity and quality control facilities. Two oil/grit separators exist to provide water quality treatment for more recent private development in the vicinity of the Harmony Road and Taunton Road intersection within the Wilson Subwatershed of Harmony Creek. In addition, two (2) water quality/quantity ponds are identified, which are located northwest of the Harmony/Taunton intersection (Dusty Dawn subdivision) and northeast of the Harmony Road intersection (Smart Centres). As noted, these two SWM ponds currently provide treatment for subcatchment areas H8 and H7, respectively (refer to Figure 2b). The Dusty Dawn SWM pond, which is generally bounded by Taunton Road, Leslie Court, and McCue Drive provides treatment for 40.65 ha of recently developed residential lands northwest of the Harmony Road and Taunton Road intersection (Sernas, 2005). The Smart Centres SWM pond, located immediately south of Coldstream Drive approximately 350 m east of the Coldstream Drive and Harmony Road intersection, provides treatment for 39.03 ha of recently developed commercial lands northeast of the Harmony Road and Taunton Road intersection (Counterpoint, 2007). As also noted above, a wet SWM pond also exists within the Harmony Horizons subdivision, which currently conveys drainage from subcatchment area H5 (refer to Figure 2b). This existing wet pond collects drainage from approximately 24.07 ha of Harmony Horizons subdivision plus an additional 34.91 ha of drainage from external area, which generally includes subcatchment area H5 and existing residential development east of Harmony Road (D.G. Biddle, 2005). It appears that no other SWM facilities exist that provide either water quality or quantity controls for Harmony Road through the Study Area.

2.2

HARMONY CREEK FLOODPLAIN

As noted above, the Study Area includes a watercourse crossing (Hoskin Bridge) over the main branch of Harmony Creek. A recent floodplain mapping study of Harmony Creek (Aquafor Beech Ltd, June 2010) indicates the following noteworthy points:

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT • • • •

The existing bridge opening measures approximately 4.42 m high by 12.60 m wide by approximately 22.17 m long; The Regional Flood does NOT overtop Harmony Road; identified as Structure No. 28 in the above referenced document; Regional Flood elevations at the immediate upstream and downstream side of the Harmony Road are 133.24 m and 132.34 m, respectively; and Per the Study, the lowest weir elevation along Harmony Road (sag elevation where spilling can occur over the roadway) is approximately 134.78 m. The flood level is approximately 1.54 m below the sag at the upstream and 2.44 m below the sag at the downstream.

As such, altering the existing roadway profile through this vicinity will not influence the existing floodplain since the roadway is reasonably well above the calculated Regional Storm watersurface elevation. In the event that alternative options are considered that will propose to widen the existing bridge and abutments, then a model update should be completed to confirm that there will be no adverse impacts to the existing floodplain and adjacent properties and existing infrastructure. Given the existing low-flow hydraulic regime (ie. no pressure and/or weir flow) through the existing bridge crossing and when considering the relatively steep channel profile through the immediate upstream reach of Harmony Creek, it is likely that any minor bridge widening to accommodate the widened roadway through this vicinity would have a negligible impact on the existing Regional flood profile.

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

3.0

Stormwater Management Design Criteria

The subject Class EA addresses the proposed modifications to Harmony Road generally located between Conlin Road and Rossland Road (refer to Figure 1). The Central Lake Ontario Conservation Authority (CLOCA) has established the following SWM design criteria for the Black/Harmony/Farewell Creek Watershed. Stormwater management measures recommended as part of this Class EA will attempt to satisfy CLOCA’s SWM criteria to the greatest extent practicable.

3.1

WATER QUALITY CONTROL

Based on the Black/Harmony/Farewell Creek Watershed Existing Conditions Report, the surface water quality in Harmony Creek at the Hoskin Bridge is considered to be fairly poor, exhibiting increasing trends of chloride and generally high levels of phosphorus, both of which exceed the Provincial Water Quality Objectives (PWQO). Measured concentrations of nitrate and copper were relatively low and do not exceed recommended concentrations by Environment Canada and the PWQO, respectively. The Ministry of Environment’s (MOE) Stormwater Management Planning and Design Manual (SWMPDM) includes a volumetric sizing guideline for the removal of suspended sediments that is based on the various types of stormwater management facility, upstream imperviousness, drainage area and level of protection required. Within the entire Black/Harmony/Farewell Creek watershed Enhanced (Level 1) Protection is required by CLOCA, as the Black/Harmony/Farewell Creeks consists primarily of cool water fisheries and drains to a provincially significant coastal wetland.

3.2

WATER QUANTITY CONTROL

Stormwater quantity control criteria within CLOCA’s jurisdiction have been set by CLOCA, with reference to the MOE’s SWMPDM. CLOCA mandates that: • •

• •

3.10

every effort should be made to maintain existing watershed boundaries and drainage patterns; unless specified otherwise by the municipality, subwatershed study, or fluvial geomorphic analysis, the post-development peak flow rates must not exceed corresponding pre-development rates for the 1:2-year through 1:100-year design storm events and the Regional Event (Hurricane Hazel); if there are known undersized pipes/culverts downstream that could impede water conveyance or if there is private property within the riparian area that could be affected, then quantity control must be provided; and In the lower and mid-portions of the watershed it is preferable to discharge drainage from new developments without stormwater quantity controls, so that this drainage can flow through the system before the larger discharges from the upper portion of the watershed are routed through the adjacent natural drainage system.

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

3.3

EROSION & SEDIMENT CONTROL

Sedimentation and erosion control within CLOCA’s jurisdiction is jointly prescribed by CLOCA and the MOE. The MOE SWMPDM requires that the 25 mm 4 hr Chicago storm be stored and released over a 24-hr to 48-hr period. This ensures that the peak flows are released slowly reducing high volumes and velocities that can cause downstream erosion. In addition, preventative measures must be taken during construction activities to reduce the transport of sediments from the stripped site to waterways. Such measures include silt fencing, rock check dams and sedimentation ponds. These measures slow the rate at which stormwater runoff drains and encourage the settling out of suspended sediments.

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

4.0

Alternative Designs

Four through lanes are required to accommodate projected travel demands throughout the Study Area. Left turn lanes were identified based on turning traffic volumes. For design development and assessment the Study Area was divided into three sections as noted below: 1. Rossland Road to Grand Ridge Avenue 2. Grand Ridge Avenue to Coldstream Drive 3. Coldstream Drive to Conlin Road For each section of roadway the following alternatives were considered. Alternative 1: Do Nothing •

This alternative was used as a base case for comparison.

Alternative 2: 4 Lane Harmony Road (2 Through Lanes Each Direction) •

This alternative has 2 through lanes in each direction and left turns at the signalized intersections.

Alternative 3: 5 Lane Harmony Road (2 Through Lanes in Each Direction + 5 m Continuous Left Turn Lane) •

This alternative has 2 through lanes in each direction and has a continuous 5 m left turn land for the whole length of roadway section.

A review of the above referenced general alternatives yielded a preferred alternative to include 5 lanes from Grand Ridge Avenue to Conlin Road and 4 lanes plus select left turn lanes at key intersections for the roadway south of Grand Ridge Avenue. The resulting preferred alternative includes the following key elements: • • • • • • • • • • 4.12

Widen Harmony Road to 4 through lanes (2 through lanes in each direction) plus a continuous centre turn lane from Grand Ridge Avenue to Conlin Road. Maintain existing Hoskin Bridge. Provide a traffic signal at the Harmony Road / Conlin Road intersection including exclusive left turn lanes on all approaches. Provide sidewalk on both sides of Harmony Road. Construct a 1.7 m median island at Pinecrest Road to use right-in, right-out movements. Provide a southbound left turn lane to Swiss Heights. Extend the existing median island south of Taunton Road by approximately 60 m. Extend the existing median island north of Taunton Road by approximately 60 m (or 250 m in the ultimate scenario). Construct Harmony Road to an urban cross-section (provide curb and gutter) north of Coldstream Drive on the east side and north of Taunton Road on the west side. Provide continuous illumination on Harmony Road north to Conlin Road. V:\01602\active\160210516 - Harmony Road Class EA\SWM\rpt_Final_SWM_Report_May_2011.doc

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

5.0

Mitigation Measures

Potential measures to improve storm drainage and water quality through the Study Area were explored as part of the Class EA. These options should be considered for implementation at the detailed design stage.

5.1

STORMWATER MANAGEMENT

Roadway runoff, if left untreated, has the potential to impact receiving watercourses. Pollutants commonly found in roadway runoff include, but are not necessarily limited to: TSS, phosphorus, hydrocarbons, metals, chlorides and various nutrients, all of which can impair the aquatic ecosystem of the receiving watercourse. Increasing the amount of impervious surface by accommodating a widened roadway will also generate a greater volume and rate of surface water runoff into the collection system (existing and proposed stormsewer) and ultimately into the receiving watercourse. A summary of the existing and proposed impervious areas that drain to each outlet is summarized in Table 5.1 below. Refer to Figure 2a through Figure 2c for an illustration of the existing outlet locations. Table 5.1: Surface Drainage Outlet Characteristics Outlet ID1 Roadway Receiving Total Station System at Study Drainage Area Outlet Area (ha) H1 0+000 Stormsewer 0.97 H2 0+275 Open Swale Unknown H3 0+460 Harmony Creek 0.89 H4 0+500 Harmony Creek 8.45 H5 1+295 Stormsewer 34.39 H6 1+475 Abandoned 0.00 Open Swale H7 1+990 Stormsewer 2.83 H8 2+575 Stormsewer 3.30 H9 3+750 Open Swale 1.56 C1 0+000 Open Swale 8.60 C2 0+270 Open Swale 3.50 C3 0+420 Open Swale 12.50 C4 0+630 Open Swale 12.50

Prop. ROW Area (ha) 0.97 0.00 0.72 1.64 2.59 0.00

Ex. ROW Impervious Area (ha) 0.44 0.00 0.26 0.73 1.20 0.00

Prop. ROW Impervious2 Area (ha) 0.62 0.00 0.38 1.25 1.69 0.00

2.11 3.01 1.56 0.88 0.75 0.85 0.68

1.04 0.86 0.67 0.18 0.18 0.22 0.14

1.21 2.00 1.09 0.34 0.33 0.35 0.22

1.The pre-fix ‘H’ and ‘C’ denote Harmony and Conlin. The referenced roadway station is specific to each separate roadway. 2.For the purpose of the proposed conditions, the preferred alternative was considered for the impervious area tabulation.

As noted above and within the referenced figures, the Study Area includes several drainage outlets. The combined total proposed right-of-way area within the Study Area is approximately 15.8 ha with an existing and proposed impervious area of approximately 5.92 ha and 9.48 ha, respectively. As such, there will be a 3.56 ha increase to the impervious area within the proposed right-of-way. Please note that Outlet H2 directs drainage from portions of the V:\01602\active\160210516 - Harmony Road Class EA\SWM\rpt_Final_SWM_Report_May_2011.doc

5.13

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT residential subdivision generally located northeast of the intersection of Rossland Road and Harmony Road but does not collect any drainage from Harmony Road itself. In addition, Outlet H6 previously existed as a storm sewer outlet into an open drainage swale (Durham Region, 1985); however, as a result of the more recently developed Harmony Horizons subdivision, this outlet has since been plugged and the flows diverted approximately 180 m south using the existing Harmony Road stormsewer to Outlet H5 (D.G. Biddle, 2000). Outlet H5 was also modified from an open swale outlet to a municipal stormsewer as a result of the Harmony Horizons subdivision, which are now conveyed to a SWM pond via City municipal stormsewer for treatment (D.G. Biddle, 2000). SWM practices for the management of roadway runoff generally fall into the categories of water quantity and water quality of surface runoff. Water quantity management issues relate to properly sizing watercourse crossings of the roadway corridor, as well as the conveyance of roadway runoff along the roadway corridor for minor and major storm events. In addition, water quantity management strategies can include the need for facilities to address downstream flood and erosion potential from the development (expansion) of the roadway right-of-way. The term water quality relates to the treatment of the run-off from new pavement and where possible, the treatment of run-off from existing pavement; however, current legislation is related to the former. Typically, the treatment level is related to the standards defined in the watershed or sub-watershed planning study, which are dependent on the quality and sensitivity of the receiving stream system. As noted in Section 3.1, Harmony Creek requires that the MOE Level 1 (Enhanced) water quality controls be utilized. Various SWM practices are available to address both the quantity and quality of runoff from roadways. Due to the linear nature of roadway corridors, however, the full spectrum of SWM practices is typically not appropriate. There are a number of SWM measures that can be used to treat runoff and/or control peak flows from roadway surfaces. These generally include the following:

• • • • • •

Wet ponds/wetlands/hybrids; Grassed swales alone or grassed swales with rock check dams; Oil and grit separators; Catchbasin filter inserts; Off-site stormwater management facilities; and Cash-in-lieu of on-site treatment.

The respective characteristics, advantages and disadvantages of the SWM alternatives referenced above have been well documented in previous municipal and provincial literature; as such, this information has not been repeated again within this document. 5.1.1

Water Quality Control

South of Taunton Road In general, the feasibility of implementing conventional end-of-pipe SWM alternatives for the central and southern portion of the Study Area is limited due to the existing urban roadway section and spatial constraints. Fully developed commercial and residential lands reside immediately adjacent to Harmony Road throughout this vicinity. As such, water quality control 5.14

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT treatment alternatives are generally limited to the use of oil/grit separators or catch basin filter inserts. Filter inserts are generally less preferred due to the extensive maintenance requirements. Although there are four (4) drainage outlets located along the south/central portion of the Study Area, three (3) outlets (H1, H3 and H4) currently runoff without any treatment. These three subcatchments collect approximately 56% of the right-of-way drainage for portions of the Study Area located south of Taunton Road. The only remaining outlet (Outlet H5) currently directs water to the Harmony Horizons SWM pond, which provides Level 2 (Normal) water quality treatment for the contributing Harmony Road right-of-way. Although this pond was not originally designed to treat the ultimate Harmony Road configuration, the additional flow contribution as a result of the widening and associated increase in impervious area (0.49 ha) is considered to be negligible (less than 1%) when considering the overall contributing area to the SWM pond is 58.98 ha. In order to avoid the potential for excessive maintenance requirements associated with installing treatments at 3 separate outlet locations, it is recommended that water quality treatment focus on the H4 outlet since it currently drains the largest amount of area among the 3 untreated outlets, including some untreated existing residential development to the east along Harmony Road and Pinecrest Road. Installing an oil/grit separator at this location to treat for all contributing drainage area would treat approximately 2.64 ha of impervious area, which is greater than the proposed 1.31 ha of increased impervious area proposed along Harmony Road south of Taunton Road. This approach would provide a net improvement when compared to the existing conditions. Installing an oil/grit separator at both Outlet H1 and H3 to treat the full contributing drainage areas to each would not treat an amount of impervious area greater than the proposed 1.31 ha increase through this vicinity. As such, installing an OGS near the H4 outlet and allowing H1 and H3 to continue to drain without treatment is recommended to offset the effects associated with the proposed roadway widening. North of Taunton Road The northern portion of the Study Area currently includes a rural roadway section. Several smaller drainage outlets exist through this vicinity as noted in Table 5.1 above. Although there are seven (7) existing outlet locations, it is arguable that the impacts to the four (4) outlets along Conlin Road (C1 through C4) are negligible, since the maximum increase in paved surface to either of these outlets does not exceed more than 0.20 ha, each outlet will be directed into vegetated swales, and the increase in impervious area relative to the contributing drainage area is considerably less. As such, the respective vegetated outlets along Conlin Road are assumed to provide sufficient water quality enhancements for Outlets C1 through C4. Outlet H7 currently drains to the Dusty Dawn SWM pond, which was designed to provide water quality/quantity controls for the ultimate Harmony Road conditions (Sernas, 2005). As such, no further water quality controls to treat this area are necessary. Outlet H8 currently drains to the Smart Centres SWM pond, which was also designed to provide quality/quantity controls for the ultimate Harmony Road conditions (Counterpoint, 2007). As such, no further water quality controls to treat this area are necessary. Harmony Road right-of-way area contributing to Outlet H9 is intended to ultimately be treated by a SWM pond located on private lands east of Harmony Road, as outlined in the Stormwater Management Master Plan (Taunton Community – Harmony Creek), dated October 2004. As outlined on Drawing CS-1, which accompanied the Master Plan and is provided again with this V:\01602\active\160210516 - Harmony Road Class EA\SWM\rpt_Final_SWM_Report_May_2011.doc

5.15

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT SWM Brief for reference in Appendix C, stormsewer was envisioned to convey right-of-way drainage in a southerly direction to the future ‘Greenhill Avenue’, located approximately 610 m south of the Harmony Road and Conlin Road intersection. Since the development of these private lands east of Harmony Road have not proceeded to date and no timeframe for such development is presently known, it is recommended that the roadway drainage continue to be conveyed to the existing low point at Station 3+750 (Outlet H9) and that future development of these private lands pick-up the roadway drainage at this location, rather than the future Greenhill Avenue. These flows can continue to be conveyed to the future SWM pond, in accordance with the SWM Master Plan, when the development of these lands proceeds. A proper drainage outlet under the existing conditions cannot be accommodated at the future Greenhill Avenue due to topographic constraints. Although this stormsewer configuration deviates from the original alignment shown on Drawing CS-1, it is considered to be more practical, less costly, and easily accommodated by the future development since the Master Plan alignment would require a greater amount of stormsewer length to capture the same area and a stormsewer depth at the intersection of the future Greenhill Avenue and Harmony Road in excess of 6 m. Under the interim condition, that is until the lands east of Harmony Road are developed, directing drainage across the open field, as observed under the existing conditions, is the recommended water quality treatment alternative. Care shall be taken at the detailed design phase to ensure that the outlet is properly equipped with energy dissipation (rip rap lined plunge pool) and spread into existing vegetation to mitigate for any increased erosive effects that may result from more concentrated flows at the proposed stormsewer outlet. All proposed water quality treatment control devices shall be sized in accordance with the MOE’s SWMPDM and all municipal design standards. 5.1.2

Water Quantity Control

As indicated in the Black/Harmony/Farewell Creek Watershed Existing Conditions Report, …”In the lower and mid-portions of the watershed it is preferable to discharge drainage from new developments without stormwater quantity controls, so that this drainage can flow through the system before the larger discharges from the upper portion of the watershed are routed through the adjacent natural drainage system.” Based on the proximity of the south/central portion of the Study Area, water quantity controls should not be required for the proposed roadway widening. Conversely, the northern Study Area is located in the upper portion of the Harmony Creek Watershed and would typically be subject to providing water quantity controls. As noted above, Outlets H7 & H8 currently drain to existing SWM facilities, which have accommodated the ultimate Harmony Roadway quantity control requirements. As such, no further water quantity control measures are necessary at these outlets. As also noted above, ultimately Outlet H9 will be conveyed to a SWM quantity/quality pond on private lands, as outlined in the SWM Master Plan (refer to Appendix C). Under the interim conditions, the marginal increase in runoff expected from the roadway widening at H9 is considered to be negligible. In the interim, the proposed stormsewer shall outlet into an energy dissipator and vegetated level spreader to ensure no erosive impacts on receiving private lands scheduled for future development. Any construction (if required) outside the Harmony Road 5.16

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT right-of-way will require permission from the adjacent private property owner. When development of the private lands proceed, the developer shall be responsible for designing and constructing a SWM quality/quantity control facility to treat runoff from the widened Harmony Road. Although the anticipated increase in runoff associated with the improvements at the Conlin Road intersection (Outlets C1 through C4) could rely upon the existing roadside drainage swales equipped with rock check dams for quantity controls, the anticipated increases in runoff are considered to be negligible. However, consideration to implement rock check dams within the existing Conlin Road drainage ditches should be explored further at detailed design. 5.1.3

Erosion & Sediment Control

As noted above, since the Study Area is spatially constrained conventional end-of-pipe alternatives are not feasible. As such, portions of the Study Area that will include an urban roadway section will not need the 25 mm 4-hr Chicago Storm extended detention volume. In the event that a rural roadway section will remain within the northern portion of the Study Area, then the extended detention is achievable within roadside swales equipped with rock check dams and/or infiltration trenches. A detailed Erosion and Sediment Control Plan should be provided at the detailed design stage. As a minimum, it is recommended that the Erosion and Sediment Control Plan incorporate the following measures: •

Erect heavy duty silt fences prior to grading or construction adjacent to the Harmony Creek valley corridor, the undeveloped landscape in the northern portion of the Study Area and existing road right-of-ways that are down gradient along the perimeter of the Study Area to protect adjacent and downstream areas from migration of sediment in overland flow;



Erect tree protection fencing prior to grading or construction along the outside perimeter of drip lines of preserved trees in consultation with environmental consultant;



Provide erosion control filters around existing adjacent catch basins during construction;



Provide a construction entrance feature (“mud mat”) to minimize the offsite transport of sediment from construction vehicle tires on the adjacent municipal road right-of-ways;



Install temporary rock check dams in swales where appropriate to help attenuate flows and encourage sediment deposition;



Install erosion control matting on all steep (>3:1) slopes; and



Stabilize all disturbed areas according to OPSS 572;

To ensure the effectiveness of the various erosion and sediment control measures, an appropriate inspection and maintenance program is necessary. The inspection activities should include weekly inspections or after each significant rainfall event (>15 mm), with consideration for all silt fence installations, sediment traps and temporary impoundments, outlets and vegetation. It is also recommended that monitoring reports be submitted to the Region and CLOCA during active construction periods. Alternatively, a designated environmental monitor may be designated onsite to ensure that all erosion and sediment control devices remain intact and function as intended by design. V:\01602\active\160210516 - Harmony Road Class EA\SWM\rpt_Final_SWM_Report_May_2011.doc

5.17

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

6.0

Storm Sewer Capacity Assessment

Outlet capacities of the receiving systems for each proposed drainage outlet were reviewed as part of this assessment. A summary of these capacities for the 1-, 2-, 5-, and 10-year storm events is summarized in Table 6.1 below. A stormsewer is considered to be at capacity when flows are conveyed by gravity without any pressure flow within the pipe. Once the water-surface elevation within the stormsewer exceeds the height of the pipe obvert, the system is considered to be flowing under pressure, and above the regular gravity conveyance capacity of the pipe. Refer to Figure 2a through Figure 2c for the outlet locations. Calculations are provided in Appendix A. Table 6.1: Stormsewer Outlet Capacity Assessment Summary Outlet ID1 Storm Recurrence Interval 1-year 2-year 5-year Ex. Prop. Ex. Prop. Ex. Prop. 36.7% 47.2% 44.6% 57.4% 55.4% 71.4% H1 N/A N/A N/A N/A N/A N/A H2 33.7% 43.9% 41.0% 53.4% 50.4% 65.7% H3 54.9% 64.0% 66.6% 77.7% 84.8% 99.0% H4 84.3% 86.8% 102.4% 105.4% 129.4% 133.2% H5 N/A N/A N/A N/A N/A N/A H6 91.3% 101.5% 110.9% 123.3% 138.6% 154.0% H7 22.8% 47.7% 27.7% 58.0% 34.8% 73.0% H8

10-year Ex. Prop. 69.2% N/A 62.7% 107.3% 162.9% N/A 173.5% 43.8%

89.2% N/A 81.7% 125.2% 167.7% N/A 192.8% 91.7%

1.The pre-fix ‘H’ and ‘C’ denote Harmony and Conlin.

As noted, Outlet H2 is a stormsewer that drains underneath Harmony Road, which only collects drainage from a residential subdivision located to the east. As such, no assessment was required for this Outlet. In addition, H6 was previously removed as a result of the Harmony Horizons residential development and also did not require any assessment. Drainage that previously discharged into an open swale at H6 was redirected approximately 180 m south along Harmony Road to outlet H5. Outlet H5 is currently captured by a municipal stormsewer and conveyed through the residential subdivision to the Harmony Horizons SWM pond. The design of that particular stormsewer applied the City of Oshawa stormsewer design standard, which requires a 1-year design storm for the minor system. In summary, H1, H3, and H4, will all convey a 5-year storm under the proposed conditions. Outlet H5 and H7 will generally be limited to a 2-year and 1-year storm conveyance capacity, respectively. Although Outlet H7 will only slightly exceed a 1-year capacity, there is no anticipated adverse impact to the existing storm sewer or receiving SWM pond. Outlet H8 has capacity to convey a 10-year storm under the proposed conditions, which will direct drainage easterly along Coldstream Drive into the Smart Centres SWM pond. All other outlets not referenced in Table 6.1 above will discharge freely into vegetated swales and do not require capacity assessment. A stormsewer CCTV inspection was conducted on January 18th and January 19th, 2010. The general conditions of the stormsewers are considered to be satisfactory with some notable deficiencies, which hinder the overall system to be considered in ‘good’ condition. Please refer to Appendix B for the full report summary. 6.18

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

All new stormsewers shall be designed in accordance with the Region of Durham’s stormsewer design standards. Minor system drainage for the Region of Durham currently requires that all new stormsewer be designed to convey the 10-year storm unless discharging into an existing stormsewer system, in which case a 5-year design storm may be considered for design.

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6.19

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

7.0

Conclusion

This report has demonstrated that the proposed improvements to Harmony Road may proceed in general conformance with the applicable Region, City, and CLOCA SWM requirements. The findings of this report are summarized as follows: •

Minor and major system flows from the Study Area will be conveyed to eleven (11) separate existing outlet locations. Seven (7) of these outlets are located along Harmony Road while the remainder are along Conlin Road;



No SWM quality controls currently exist along Harmony Road right-of-way, aside for the vegetated roadside swales along the northern portion of the Study Area;



Three existing SWM ponds exist on adjacent commercial/residential developments, which will treat runoff from the widened Harmony Road at subcatchments H5, H7, and H8;



A future SWM pond will capture and treat runoff from subcatchment H9 as part of future development on lands east of Harmony Road. In the interim, the proposed stormsewer shall outlet into an energy dissipator and vegetated level spreader to ensure no erosive impacts on receiving lands scheduled for future development;



SWM quality controls may proceed in the form of an oil/grit separator at Outlet H4 to treat a level of impervious area from the widened Harmony Road and adjacent residential development to mitigate for the increased level of imperviousness south of Taunton Road;



Consideration to provide water quantity/quality controls within roadside ditches along Conlin Road to treat runoff at Outlets C1, C2, C3, and C4 should be explored further at detailed design;



Capacity of outlets that will discharge to existing stormsewer will generally range between a 1-year and 10-year storm;



Existing stormsewer within Harmony Road is considered to be in a satisfactory condition with some notable deficiencies that will require rehabilitation works;



The proposed roadway improvement will not have any impact on the existing Harmony Creek Regional Storm floodplain. In the event that Hoskin Bridge is to be widened, then an updated hydraulic model should be prepared to confirm that no adverse impacts will result from the potential widening; and



The SWM strategy for the proposed roadway improvements has been reviewed and approved by CLOCA (refer to Appendix D).

7.20

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HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT All of which is respectfully submitted, STANTEC CONSULTING LTD.

Tim Gallagher, M.Sc., P. Eng., P.E. Water Resources Project Manager Tel : (905) 944-6870 Fax: (905) 474-9889 [email protected]

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7.21

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

APPENDIX A STORMSEWER CAPACITY ASSESSMENT AND HYDROLOGIC CALCULATIONS

0+000 0+275 0+460 0+500 1+295 1+460 1+990 2+575 3+750 0+000 0+270 0+420 0+630

Station

0.00 N/A 0.17 6.79 31.80 0.00 0.72 0.29 0.00 7.72 2.75 11.65 11.82

~ External Contributing Area1 (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50

~ Total Contributing Area @ Outlet (ha) 0.44 0.00 0.35 2.64 14.57 0.00 1.36 0.86 0.67 0.18 0.18 0.22 0.14

~ Impervious Area (ha) 45.4% 0.0% 38.8% 31.2% 42.4% 0.0% 48.2% 26.1% 42.9% 2.1% 5.1% 1.8% 1.1%

Percent Impervious (%)

Where: i = Average Rainfall Intensity (mm/hr) - for a given storm duration (td) td = Storm Duration (min) a, b, c = rainfall equation coefficients a= 519.5 1-Year Storm IDF Parameters as per City of b= 4 Oshawa c= 0.7755

i = a/(tc + b)c

1. Area beyond drainage from within adjacent frontage onto ROW and ROW.

H1 H2 H3 H4 H5 H6 H7 H8 H9 C1 C2 C3 C4

Outlet ID

Pre-Development Conditions Existing 1-year Storm Capacity

MODIFIED RATIONAL METHOD

0.46 0.00 0.40 0.33 0.43 0.00 0.48 0.28 0.44 0.20 0.20 0.20 0.20

Runoff Coefficient1 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

(min)

Time tc

49.6 0.0 52.3 43.1 45.4 0.0 48.5 46.5 44.5 44.5 53.4 44.5 44.5

(mm/hr) 0.061 N/A 0.052 0.335 1.872 0.000 0.184 0.121 0.084 0.212 0.104 0.309 0.309

(m /s)

3

Intensity Flow i=a/(td+b)^c Qp=CiA/360

0.167 N/A 0.153 0.610 2.219 1.389 0.202 0.532 Free Free Free Free Free

(m /s)

3

Outlet Capacity

36.7% N/A 33.7% 54.9% 84.3% N/A 91.3% 22.8% N/A N/A N/A N/A N/A

Percent Capacity

0+000 0+275 0+460 0+500 1+295 1+460 1+990 2+575 3+750 0+000 0+270 0+420 0+630

0.00 N/A 0.17 6.79 31.80 0.00 0.72 0.00 0.00 7.72 2.75 11.65 11.82

~ External Contributing Area1 (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50

~ Total Contributing Area @ Outlet (ha) 0.62 0.00 0.47 3.16 15.06 0.00 1.53 2.00 1.09 0.34 0.33 0.35 0.22

~ Impervious Area (ha) 60.0% 0.0% 52.2% 37.4% 43.8% 0.0% 54.2% 60.7% 69.7% 4.0% 9.4% 2.8% 1.8%

Percent Impervious (%) 0.59 0.00 0.52 0.39 0.44 0.00 0.54 0.60 0.68 0.20 0.20 0.20 0.20

Runoff Coefficient1,2 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

(min)

Time tc

49.6 0.0 52.3 43.1 45.4 0.0 48.5 46.5 44.5 44.5 53.4 44.5 44.5

(mm/hr)

Where: i = Average Rainfall Intensity (mm/hr) - for a given storm duration (td) td = Storm Duration (min) a, b, c = rainfall equation coefficients a= 519.5 1-Year Storm IDF Parameters as per City of b= 4 Oshawa c= 0.7755

i = a/(tc + b)c

0.079 N/A 0.067 0.391 1.928 0.000 0.205 0.254 0.130 0.212 0.104 0.309 0.309

(m3/s)

Intensity Flow i=a/(td+b)^c Qp=CiA/360

1. Area beyond drainage from within adjacent frontage onto ROW and ROW. 2 - Assumed Runoff Coefficient from % Impervious Area using Simple Method, C = 0.05 + 0.009(I) - (Schueler, 1987); minimum Runoff Coefficient assumed to be 0.20

H1 H2 H3 H4 H5 H6 H7 H8 H9 C1 C2 C3 C4

Outlet ID

Station

Post-Development Conditions Existing 1-year Storm Capacity

0.167 N/A 0.153 0.610 2.219 1.389 0.202 0.532 Free Free Free Free Free

(m3/s)

Outlet Capacity

47.2% N/A 43.9% 64.0% 86.8% N/A 101.5% 47.7% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50

c

Percent Impervious (%) 45.4% 0.0% 38.8% 31.2% 42.4% 0.0% 48.2% 26.1% 42.9% 2.1% 5.1% 1.8% 1.1%

Where: i = Average Rainfall Intensity (mm/hr) - for a given storm duration (td) td = Storm Duration (min) a, b, c = rainfall equation coefficients a= 647.7 2-Year Storm b= 4 IDF Parameters as per City of c= 0.784 Oshawa

i = a/(tc + b)

0.44 0.00 0.35 2.64 14.57 0.00 1.36 0.86 0.67 0.18 0.18 0.22 0.14

~ Impervious Area (ha)

1. Area beyond drainage from within adjacent frontage onto ROW and ROW.

Pre-Development Conditions Existing 2-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.29 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82

MODIFIED RATIONAL METHOD

0.46 0.00 0.40 0.33 0.43 0.00 0.48 0.28 0.44 0.20 0.20 0.20 0.20

Runoff Coefficient1

Time tc (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 60.3 0.074 0.167 0.0 N/A N/A 63.6 0.063 0.153 52.3 0.406 0.610 55.2 2.272 2.219 0.0 0.000 1.389 58.9 0.224 0.202 56.4 0.147 0.532 54.0 0.102 Free 54.0 0.258 Free 64.9 0.126 Free 54.0 0.375 Free 54.0 0.375 Free 44.6% N/A 41.0% 66.6% 102.4% N/A 110.9% 27.7% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50 0.62 0.00 0.47 3.16 15.06 0.00 1.53 2.00 1.09 0.34 0.33 0.35 0.22

~ Impervious Area (ha)

Percent Impervious (%) 60.0% 0.0% 52.2% 37.4% 43.8% 0.0% 54.2% 60.7% 69.7% 4.0% 9.4% 2.8% 1.8% 0.59 0.00 0.52 0.39 0.44 0.00 0.54 0.60 0.68 0.20 0.20 0.20 0.20

Runoff Coefficient1,2

Time tc (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 60.3 0.096 0.167 0.0 N/A N/A 63.6 0.082 0.153 52.3 0.474 0.610 55.2 2.340 2.219 0.0 0.000 1.389 58.9 0.249 0.202 56.4 0.308 0.532 54.0 0.158 Free 54.0 0.258 Free 64.9 0.126 Free 54.0 0.375 Free 54.0 0.375 Free

Where: i = Average Rainfall Intensity (mm/hr) - for a given storm duration (td) td = Storm Duration (min) a, b, c = rainfall equation coefficients a= 647.7 2-Year Storm b= 4 IDF Parameters as per City of c= 0.784 Oshawa

i = a/(tc+ b)c

1. Area beyond drainage from within adjacent frontage onto ROW and ROW. 2 - Assumed Runoff Coefficient from % Impervious Area using Simple Method, C = 0.05 + 0.009(I) - (Schueler, 1987); minimum Runoff Coefficient assumed to be 0.20

Post-Development Conditions Existing 2-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.00 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82 57.4% N/A 53.4% 77.7% 105.4% N/A 123.3% 58.0% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50

i = 2464/(Tc+16) (per Region Standards)

1. Area beyond drainage from within adjacent frontage onto ROW and ROW.

Pre-Development Conditions Existing 5-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.29 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82

MODIFIED RATIONAL METHOD

0.44 0.00 0.35 2.64 14.57 0.00 1.36 0.86 0.67 0.18 0.18 0.22 0.14

~ Impervious Area (ha)

Percent Impervious (%) 45.4% 0.0% 38.8% 31.2% 42.4% 0.0% 48.2% 26.1% 42.9% 2.1% 5.1% 1.8% 1.1% 0.46 0.00 0.40 0.33 0.43 0.00 0.48 0.28 0.44 0.20 0.20 0.20 0.20

Runoff Coefficient1

Time td (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 75.0 0.093 0.167 0.0 N/A N/A 78.2 0.077 0.153 66.6 0.517 0.610 69.7 2.872 2.219 0.0 0.000 1.389 73.6 0.280 0.202 71.0 0.185 0.532 68.4 0.129 Free 68.4 0.327 Free 79.5 0.155 Free 68.4 0.475 Free 68.4 0.475 Free 55.4% N/A 50.4% 84.8% 129.4% N/A 138.6% 34.8% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50 0.62 0.00 0.47 3.16 15.06 0.00 1.53 2.00 1.09 0.34 0.33 0.35 0.22

~ Impervious Area (ha)

Percent Impervious (%) 60.0% 0.0% 52.2% 37.4% 43.8% 0.0% 54.2% 60.7% 69.7% 4.0% 9.4% 2.8% 1.8% 0.59 0.00 0.52 0.39 0.44 0.00 0.54 0.60 0.68 0.20 0.20 0.20 0.20

Runoff Coefficient1,2

Time td (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 75.0 0.119 0.167 0.0 N/A N/A 78.2 0.101 0.153 66.6 0.604 0.610 69.7 2.957 2.219 0.0 0.000 1.389 73.6 0.311 0.202 71.0 0.388 0.532 68.4 0.201 Free 68.4 0.327 Free 79.5 0.155 Free 68.4 0.475 Free 68.4 0.475 Free

i = 2464/(Tc+16) (per Region Standards)

1. Area beyond drainage from within adjacent frontage onto ROW and ROW. 2 - Assumed Runoff Coefficient from % Impervious Area using Simple Method, C = 0.05 + 0.009(I) - (Schueler, 1987); minimum Runoff Coefficient assumed to be 0.20

Post-Development Conditions Existing 5-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.00 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82 71.4% N/A 65.7% 99.0% 133.2% N/A 154.0% 73.0% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50

i = 3453/(Tc+20) (per Region Standards)

1. Area beyond drainage from within adjacent frontage onto ROW and ROW.

Pre-Development Conditions Existing 10-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.29 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82

MODIFIED RATIONAL METHOD

0.44 0.00 0.35 2.64 14.57 0.00 1.36 0.86 0.67 0.18 0.18 0.22 0.14

~ Impervious Area (ha)

Percent Impervious (%) 45.4% 0.0% 38.8% 31.2% 42.4% 0.0% 48.2% 26.1% 42.9% 2.1% 5.1% 1.8% 1.1% 0.46 0.00 0.40 0.33 0.43 0.00 0.48 0.28 0.44 0.20 0.20 0.20 0.20

Runoff Coefficient1

Time td (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 93.7 0.116 0.167 0.0 N/A N/A 97.2 0.096 0.153 84.3 0.654 0.610 87.8 3.615 2.219 0.0 0.000 1.389 92.1 0.350 0.202 89.2 0.233 0.532 86.3 0.163 Free 86.3 0.412 Free 98.7 0.192 Free 86.3 0.599 Free 86.3 0.599 Free 69.2% N/A 62.7% 107.3% 162.9% N/A 173.5% 43.8% N/A N/A N/A N/A N/A

Percent Capacity

~ Total Contributing Area @ Outlet (ha) 0.97 0.00 0.89 8.45 34.39 0.00 2.83 3.30 1.56 8.60 3.50 12.50 12.50 0.62 0.00 0.47 3.16 15.06 0.00 1.53 2.00 1.09 0.34 0.33 0.35 0.22

~ Impervious Area (ha)

Percent Impervious (%) 60.0% 0.0% 52.2% 37.4% 43.8% 0.0% 54.2% 60.7% 69.7% 4.0% 9.4% 2.8% 1.8% 0.59 0.00 0.52 0.39 0.44 0.00 0.54 0.60 0.68 0.20 0.20 0.20 0.20

Runoff Coefficient1,2

Time td (min) 16.87 0.00 15.52 20.98 19.35 0.00 17.48 18.69 20.00 20.00 15.00 20.00 20.00

Intensity Flow Outlet i=a/(td+b)^c Qp=CiA/360 Capacity (mm/hr) (m3/s) (m3/s) 93.7 0.149 0.167 0.0 N/A N/A 97.2 0.125 0.153 84.3 0.764 0.610 87.8 3.723 2.219 0.0 0.000 1.389 92.1 0.390 0.202 89.2 0.488 0.532 86.3 0.253 Free 86.3 0.412 Free 98.7 0.192 Free 86.3 0.599 Free 86.3 0.599 Free

i = 3453/(Tc+20) (per Region Standards)

1. Area beyond drainage from within adjacent frontage onto ROW and ROW. 2 - Assumed Runoff Coefficient from % Impervious Area using Simple Method, C = 0.05 + 0.009(I) - (Schueler, 1987); minimum Runoff Coefficient assumed to be 0.20

Post-Development Conditions Existing 10-year Storm Capacity ~ External Contributing Station Outlet ID Area1 (ha) H1 0+000 0.00 H2 0+275 N/A H3 0+460 0.17 H4 0+500 6.79 H5 1+295 31.80 H6 1+460 0.00 H7 1+990 0.72 H8 2+575 0.00 H9 3+750 0.00 C1 0+000 7.72 C2 0+270 2.75 C3 0+420 11.65 C4 0+630 11.82 89.2% N/A 81.7% 125.2% 167.7% 0.0% 192.8% 91.7% N/A N/A N/A N/A N/A

Percent Capacity

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

APPENDIX B STORMSEWER INSPECTION CCTV REPORT SUMMARY

Memo

To:

Tim Gallagher, P.Eng.

From:

Stantec Markham File:

160210516

Reference:

Ary Rezvanifar Stantec Markham

Date:

February 14, 2011

Harmony Road Improvements from Rossland Road to Conlin Road Region of Durham Sewer Inspection CCTV Report Summary

We have reviewed the Sewer Inspection reports and videos for the study area conducted by Veolia Environmental Services on January 14th, 2010, January 18th, 2010 and January 19th, 2010. The general condition of the sewers in this area is satisfactory with some notable deficiencies hindering the system from being in good condition. The more common deficiencies in the pipes were the accumulation of debris, light encrustation and the presence of surface wear. In total there was, •

1 area of longitudinal cracking;



1 area of longitudinal fracture/circumferential fracture;



1 area where the sewer link was punctured;



3 areas where surface wear was sited;



8 legs of pipe where silt or concrete debris have collected;



9 locations of light encrustation;



2 locations of medium encrustation;



1 intruding catch basin connection and;



4 areas of light/running infiltration.

Most of the noted deficiencies are occurring in or around areas where the catch basins drain into the storm pipe, notably the encrustation and infiltration deficiencies. One of the studies conducted resulted in discovering a hole in the sewer pipe between MH K30-0009 and its outfall. The hole had caused the unbolted segments at the top of the pipe to fold inward, producing an obstruction in which the camera could not pass and complete the survey. Though no infiltration at the punctured location was present, this was the one of the most severe deficiencies observed for the all of the surveyed sewer system. Another notable deficiency was observed in the sewer pipe between MH K30amr x:\active\160210516\environmental study report\supporting studies\final version of reports\appendix m - swm report\harmony road cctv report summary feb 2011.docx

February 14, 2011 Tim Gallagher, P.Eng. Page 2 of 3

0011 and MH J30-0042; where longitudinal and circumferential fractures were present. The camera also had troubles completing its survey in areas where high accumulations hard concrete, rock and silt debris had formed. Based on these observations, it is recommended that the sewers be rehabilitated through the following measures: •

flushing the sewers to remove any debris and encrustation;



parging the cracks found in the pipe;



repair the punctured hole in the sewer pipe between MH K30-0009 and the K30-OUTFALL/remove and replace the pipe;



patching areas of exposed gasket and rebar and;



grouting around the catch basin lead connections.

We trust that this adequately summarizes the current conditions of the storm drainage system for the Study Area.

STANTEC CONSULTING LTD.

Ary Rezvanifar Transportation EIT [email protected] Attachment: Storm Sewer Deficiency List for Harmony Road

February 14, 2011 Tim Gallagher, P.Eng. Page 3 of 3

Storm Sewer Deficiency List for Harmony Road Sewer Line

Deficiencies

Start MH

Finish MH

L30-0014

L30-0008

Running Infiltration (x2), Light Encrustation under CB lead (x2), Excess Debris

L30-0030

L30-0008

Light Encrustation under CB lead (x2)

L30-0030

L30-0027

Light Encrustation under CB lead

L30-0002

L30-0003

Excess Debris

L30-0003

L30-0017

Surface Wear

L30-0015

L30-0005

Surface Wear, Intruding CB Lead Connection

L30-0032

L30-0025

Encrusted Debris

K30-0002

K30-OUTFALL

Debris (Leaves and Pebbles) (x2)

K30-0005

K30-0006

Debris (Leaves and Branches), Clean the MH access steps in MH K30-0006

K30-0005

K30-0001

Medium Surface Wear, Longitudinal Crack, Debris

K30-0009 K30-OUTFALL

L30-0020 K30-0013 K30-0015 K30-0008

K30-0016 K30-0015 K30-0001 K30-0014

K30-0011

J30-0042

L30-0012

L30-0014

Light Encrustation, Punctured Sewer Pipe which has resulted in an obstruction (Study had to be abandoned) Light Encrustation at joint Medium Encrustation at joint Debris (5%), Medium Encrustation at joint Debris (5%, 25%), Light Encrustation, Running Infiltration Longitudinal Fracture / Sewer Broken, Circumferential Fracture Light Encrustation at junction, Running Infiltration

HARMONY ROAD – CLASS EA ROSSLAND ROAD TO CONLIN ROAD, OSHAWA, ON STORMWATER MANAGEMENT REPORT

APPENDIX C TAUNTON COMMUNITY SWM MASTER PLAN DRAWING CS-1