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Appendix B.1 Storm Servicing and Stormwater Management Memorandum

AECOM 410 – 250 York Street, Citi Plaza 519 673 0510 tel London, ON, Canada N6A 6K2 519 673 5975 fax www.aecom.com

Memorandum - DRAFT

Mem-2017-10-03-SWM MEMO-60507735-Final

To Doug Law (City of London) Page 1

CC Karl Grueneis (AECOM), Peter McAllister (AECOM)

Subject

Watson Park Outlet Municipal Class Environmental Assessment – Storm Servicing and Stormwater Management

From Adam Spargo. B.Sc., Chris Moon P.Eng.

Date

3 October, 2017 Project Number 60507735

1. Introduction The City of London has engaged AECOM Canada Ltd. (AECOM) to complete a Municipal Class Environmental Assessment (EA) study for the replacement of the Watson Street storm sewer outlet that currently discharges into Watson Park. The EA study will consider the entire Watson Park drainage area and review existing storm sewer capacity, future intensification and infill development, areas of poor drainage and known flooding concerns. Various alternative strategies and solutions will be assessed that consider environmental and site specific constraints and public and agency input. The study will also focus on water quality and erosion control and consider the City’s ongoing rapid transit planning along the Wellington Road corridor. This memorandum provides a review of the existing drainage conditions and preliminary storm servicing alternatives for the evaluation of alternatives in the Municipal Class EA.

1.1 Study Area

The study area for the drainage and stormwater management investigations includes the entire Watson Park drainage area and some adjacent external catchments (refer to Figure 1). Three (3) storm sewer outlets currently discharge into Watson Park; the Watson Street outlet, Grand Avenue outlet, and Oatman Drain outlet (also referred to as Foxbar Creek). The EA will consider future redirection of external minor system catchments that could be directed to the Watson Park system to relieve capacity in adjacent storm sewers. The study area generally encompasses the area from Watson Park and Grand Avenue in the north, the CN rail line from Watson Park to Commissioners Road in the east, Commissioners Road from the CN rail line to High Street in the south, and High Street from Commissioners Road to Wellington Road in the west. The study area is located within the Upper Thames Valley Conservation Authority (UTRCA), and falls within the Central Thames Subwatershed. Watson Park is fully within the UTRCA regulated flood limit. The Watson Street outlet, along with the Oatman Drain and the Grand Avenue outlets, discharge into the Watson Park oxbow wetlands before ultimately flowing into the South Branch of the Thames River.

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Memorandum October 3, 2017


Land use within the study area is predominantly low density single detached residential, with some areas of commercial development, pockets of natural heritage features, and the Victoria Hospital and surrounding lands. While the majority of the study area is developed there is potential for future redevelopment and infill development including intensification of residential areas and expansion of the Wellington Road corridor under the City of London’s rapid transit initiatives.

2. Existing Conditions 2.1 Existing Minor System

The local minor system drainage is conveyed via storm sewers through the study area corridor. Portions of the Oatman Drain storm sewer network follow the original Foxbar Creek alignment and are located outside of the road right-of-way on private property. The study area is flat and back lot drainage is common within existing residential developments. Under existing conditions, there are three (3) minor system outlets into Watson Park. The EA study will consider the amalgamation of these outlets, among other alternatives. The drain ranges in size from 300 mm to 1350 mm diameter, however, in some locations the storm sewer diameters decrease in the downstream direction, which is not a recommended practice. Existing catchment areas have been determined based on the City of London digital elevation model data, 1 m contours, as-built drawings, site servicing plans, and field verification. Refer to Figure 2 for catchment details. General minor system conveyance for existing conditions is as follows: Watson Street

The Watson Street storm sewer ranges in size from 300 mm to 900 mm and services Watson Street and a portion of Wellington Road from Frank Place to Grand Avenue (sub-catchments A-01 to A-05). The catchment area is approximately 5.5 ha and consists of primarily low density residential and commercial land use. The Watson Street outlet is a 900 mm diameter concrete pipe that discharges into the historical oxbow at the western side of Watson Park. Some incidental water quality enhancement may occur in the oxbow wetland before entering the South Branch of the Thames River.

Oatman Drain

The Oatman Drain storm sewer follows the historic alignment of Foxbar Creek and drains an area of approximately 66 ha. The storm sewer runs along Wellington Road from Commissioners Road East to Frank Place. The system captures minor system flows from Weston Street, Bond Street, Raywood Avenue, Foxbar Road, Moore Street, Emery Street, Whetter Avenue, Thomas Janes Drive, Chester Street, Rowntree Avenue, Percy Street, Baseline Road East and Commissioners Road East. The catchment is dominated by low density residential and large commercial properties with some higher density residential areas and small pockets of undeveloped land. The catchment generally has no water quantity and quality controls with the exception of private permanent systems (PPS) providing quantity control at commercial properties 387-401 Wellington Road and 645 Commissioners Road East.

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The Oatman Drain storm sewer decreases in size from 1350 mm to 450 mm near the intersection of Rowntree Avenue and Wellington Road. The larger pipe size upstream of the 450 mm pipe is the result of previous sewer replacements and road reconstruction works. The 450 mm pipe also marks the location where the Oatman Drain storm sewer runs beneath private property. The reduction in size creates a significant decrease in the system capacity. The Oatman Drain outlet discharges into the south west corner of Watson Park providing the majority of runoff to the oxbow wetlands. Grand Avenue

The Grand Avenue storm sewer is a 600 mm sewer that captures drainage from Grand Avenue (sub-catchment D-01). According to the City of London infrastructure database, the 600 mm sewer crosses the Watson Park oxbow twice before discharging directly to the Thames River. This unusual alignment occurs because the sewer was originally a combined sewer that discharged to the former Watson Park pollution control plant (PCP). The PCP has since been removed and the sanitary component discontinued. During field inspections, AECOM staff were not able to confirm if the full length of the Grand Avenue storm sewer is in operation. It is possible that the downstream portion of the sewer has been abandoned and the outlet discharges directly to the oxbow wetland at the northern boundary of Watson Park.

Victoria Hospital

A review of the City of London’s storm sewer database and the Victoria Hospital site servicing plan identified that the storm sewer running along Wellington Road, from Wilkins Street to Commissioners Road East (sub-catchment P-01), is connected to the Victoria Hospital private storm sewer. This sewer crosses the hospital grounds from south west to north east and connects to a 1650 mm storm sewer located in the parking lot east of Baseline Road. The 1650 mm pipe conveys the minor system east to a storm water management facility that ultimately discharges to Dayus Creek. While the Wellington Road storm sewer from Wilkins Street to Commissioners Road East is not currently connected to the Oatman Drain, it is the City’s intention that this catchment will be reconnected to the future Wellington Road South trunk storm sewer.

2.2 Existing Minor System Capacity

The purpose of this study is to define the required sizing of the Watson Street outlet to accommodate future expansion of the Watson Street and Wellington Road storm sewer system. This could include replacement of the Oatman Drain and Watson Street systems with a trunk storm sewer, increased development in the catchment, and redirecting external catchments into the system. The existing outlet sewer capacity and 2-year design flow was reviewed for all outlets, and is summarized in Table 1 below. Refer to Appendix B for detailed calculations. These capacities have been determined using the City of London storm sewer design sheet.

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Table 1. Existing Storm Sewer Capacity

Storm Sewer Existing Catchment Area

(ha) Existing Outlet Capacity

(L/s) 2-Year Design Flow

(L/s)

Watson Street (900 mm) 5.5 1,425(1) 620

Oatman Drain (1200 mm) 65.9 5152 7887

Grand Avenue (650 mm) 1.0 405 110 1. The current 900 mm diameter outlet has additional capacity available; however, the 600 mm diameter sewer immediately upstream of the outlet is undersized. Based on the outlet capacity analysis, residual capacity is available in the Grand Avenue and Watson Street outlets, however, in the Watson Street sewer the 600 mm diameter sewer immediately upstream of the outlet is currently undersized and could not receive additional flows. The Oatman Drain outlet is currently undersized for the 2-year design flow along with an additional 1,610 m of the upstream trunk sewer also undersized. In particular, the reduction in pipe diameter at the intersection of Wellington Road and Rowntree Avenue from 1350 mm to 450 mm significantly reduces the sewer capacity. Significant upgrades are required in this area to prevent sewer surcharging and potential flooding. Based on a review of the storm sewer network and field verification of site conditions, it is recognized that portions of the Oatman Drain outlet drainage system are performing below current design standards. This has led to historical basement flooding within the catchment area. The following conditions exist:

• Undersized storms sewers along the Wellington Road corridor; • 2-year design storm flows conveyed overland on Wellington Road and through private

properties; • Storm sewers with diameters decreasing in the downstream direction; • Storm sewers located on private property with limited access and no easement; and • Limited formal stormwater management systems for quality control currently in place along

the corridor.

2.3 Existing Major System

The existing major system is shown in Figure 3. Within the study area, major flow routes are along the road and follow the general path of the existing storm sewer with the exception of Oatman Drain from Moore Street to its outlet at Watson Park. Through this area the major system follows the historical alignment of Foxbar Creek and is located on private property for a large portion of the remaining length. Several sag locations are present within the Oatman Drain major system that force flow overland across private property. The sag locations are as follows:

• Emery Street at Wellington Road; • Wellington Road at Moore Street; • Wellington Road at Bond Street; • Wellington Road at Weston Street; and • Wellington Road at Watson Street.

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Removal of the sag locations or high points is required to prevent spill onto private property and potential basement flooding. Alternatively, additional capacity could be provided in the minor system storm sewers to convey the 100-year event in areas of flooding concern.

3. Proposed Conditions The purpose of the EA study is to review alternatives for the upgrade of the Watson Street storm sewer outlet. These alternatives consider the following potential improvements:

• Abandonment of the Oatman Drain storm sewer and redirection of minor and major flows to the Watson Street outlet;

• Increased imperviousness in the Watson Street outlet and Oatman Drain catchment areas due to infill development/intensification, and future rapid transit planning; and

• Providing water quality control for existing development and future road widening.

3.1 Design Criteria

Stormwater Management Relevant standards and design guidelines used in the development of the stormwater management strategy include:

• The Ontario Ministry of the Environment Stormwater Management Planning and Design Manual (2003);

• The Draft Central Thames Subwatershed Study Delcan 2014; • The City of London Private Permanent Systems Policy (2010); • The City of London Design Standards (2017); • A comparison of future IDF curves for Southern Ontario, Coulibaly et al, February 2016. and • Low Impact Development Stormwater Management Planning and Design Guide (CVC, 2010); It is noted that the Ontario Ministry of Environment and Climate Change (MOECC) have recently released an Interpretation Bulletin in February 2015 regarding the ministry’s expectations on stormwater management and the use of LID practices. The MOECC recognize that conventional stormwater management practices (pipe and pond) that focus on peak flow mitigation and water quality, do not fully achieve watershed protection due to increased volume of runoff and water balance requirements. Moving forward stormwater management plans submitted for Environmental Compliance Approvals (ECAs) will consider the preservation of the natural hydrology through the use of LIDs and other source controls, where practical, feasible and appropriate. The Ministry have also clarified that LIDs are applicable and will be expected to be applied on soils with low infiltration rates (less than 15 mm/hr). The MOECC is currently preparing a LID guidance document that is expected to be release in late 2017. Ahead of this document, the CVC’s guidelines for LID (2010) have been used for the evaluation of LID as a SWM alterative.

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The 2016 document A comparison of future IDF curves for Southern Ontario includes the following conclusion: Based on the ensemble of results developed through this study, the variability among future projections should be regarded as significant, resulting in a high level of uncertainty with respect to the future IDF curves. This high level of variability is associated with levels of uncertainty, which is greatest for short-duration and moderate-to-high return period events, for example the 15- minute to 1-hour 25- to 100-year storms, making it difficult to interpret a single design threshold for water management applications. Based on this study’s results, it is recommended that further study is needed in the selected study areas to better understand and refine the uncertainties involved in the future IDF statistics. This appears necessary before major change in infrastructure design standards in the study areas. The City of London has updated their design IDF curves in 2017. The update includes the most recent climate data and trends and has been adopted for the purpose of developing design concepts. However, consideration of climate change resiliency has been incorporated in general terms. SWM objectives have been defined for the study area:

• Erosion Control: Ensure that there is no adverse impact from an increase in rates and volume of runoff;

• Water Quantity Control: The existing outlet discharges to the oxbow wetland at Watson Park which discharges directly to the South Branch of the Thames River. Quantity controls are not required for discharges to the South Branch of the Thames River, as the study area peak flow will occur significantly earlier than peak flows from the South Branch watershed; and

• Water Quality Control: Ensure that there is no adverse impact in water quality. There are currently no water quality controls provided in the Watson Street, Oatman Drain and Grand Avenue outlets drainage areas. The Central Thames Subwatershed Study (Dillon 2014) requires normal level water quality control (70 % TSS removal) for the Oatman Drain catchment. Strategic implementation of water quality control is recommended to improve existing conditions where practical. Infill and intensification within the catchment will trigger quality control measures as per the City of London Private Permanent System policy.

• Water Balance: Best efforts for improvements to the water balance will be made where practical, feasible and appropriate.

• Consideration of resiliency to climate change. Conveyance The minor system will be designed to convey the 2-year storm and the major system the 100-year storm safely with ponding no greater than 300 mm depth. Localized upsizing of the storm sewers may be required to also accommodate 100-year major flows where high or low points along Wellington Road and adjacent streets cannot be removed.

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3.2 Opportunities and Constraints

Watson Park Aquatic Habitat The Watson Street, Oatman Drain and Grand Avenue outlets provide the primary water supply for the oxbow wetlands within Watson Park. Maintaining the existing hydrologic regime is preferred to ensure the long-term sustainability of the wetland ecosystems. Relocating the Oatman Drain outlet could reduce or increase runoff volume to certain areas of the oxbow wetlands. Alternatives should consider maintaining the existing hydrologic regime at these sites. Opportunities to maintain and enhance the receiving water quality to the Watson Park oxbow wetlands are preferred for aquatic habitat enhancement and preservation. There are currently no water quality controls within the Watson Street outlet, Oatman Drain outlet and Grand Avenue outlet catchments. Improvement in water quality can be achieved through the strategic implementation of oil grit separators (OGS), best management practices (BMPs) (e.g. grassed swales, vegetated filter strips, pervious pipe systems, and infiltration basins) and/or end of pipe solutions such as a stormwater management facility (SWMF). The maximum treatment area for an OGS is typically 5 ha, therefore OGS may not be feasible for quality control in the Oatman Drain catchment because of the large number of units required. Future Development The Oatman Drain catchment area is comprised primarily of single detached residential land-use with some areas of higher density townhouses and commercial plazas. Infill and intensification of landuse will trigger the implementation of the City’s private permanent systems policy (PPS) for stormwater management, providing water quality and quantity control for these areas. The City of London’s rapid transit planning includes a rapid transit route along Wellington Road. The introduction of a rapid transit line will require widening of Wellington Road with a total of up to six (6) lanes. Rapid transit will also likely promote intensification along the corridor. Widening Wellington Road would result in an increase in imperviousness (< 5%) that would lead to an increase in peak flows, a decrease in water quality, and a change in water balance conditions (increased runoff volume and decreased infiltration and evaporation). Because Oatman Drain discharges directly to the Thames River, peak flow control will not be required. The decrease in water quality through increased sediment loading and spill contamination could be addressed through oil grit separators and BMP’s developed during future rapid transit projects. Alternatively, this increase could be addressed through an end-of-pipe system in Watson Park also designed to retrofit the existing catchment and provide water quality control for future infill development. The change in water balance conditions would need to be addressed through LID strategies which are discussed further below. Wellington Road Low Impact Development (LID) Options The follow opportunities and constraints exist for the implementation of LID strategies to address water balance requirements for the future widening of Wellington Road:

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• The proposed Wellington Road cross-section will have a narrow boulevard and will limit opportunities for inclusion of LIDs within the boulevard landscape.

• Wellington Road is an arterial road providing a major transportation corridor within the city. This increases the potential for spill contamination and overall suspended soils loading rates to potential LIDs. OGS units will address this concern;

• Soils within the study area were determined from bore hole logs obtained during the 2017 Infrastructure Renewal Program Contract 9 (Base Line Road East) and are comprised of clayey silt or sand / gravel fill over clayey silt native material. The soils are anticipated to have a moderate hydraulic conductivity promoting infiltration;

• The bore hole logs also identified the groundwater table to be greater than 6.0 m in the southern portion of the study area (Base Line Road East) and is anticipated to be at a significantly lower elevation than any potential LID inverts. Shallower groundwater may be present in the northern portion of the study area in the vicinity of the South Branch of the Thames River, specifically in Watson Park which is within the regional flood plain; and

• The Thames – Sydenham & Region Drinking Water Source Protection Mapping identifies some parts of the study area are located in a Highly Vulnerable Aquifer and Significant Ground Water Recharge area, however it is not identified as being in a Well Head Protection zone.

Based on these opportunities and constraints implementation of LID strategies is limited. An exfiltration LID solution could be employed to increase infiltration under proposed conditions and address the increase in runoff volume. The exfiltration system would be comprised of a perforated pipe beneath the boulevard, curb line or travel lane. The objective would not be to match a pre-development infiltration target or minimum retention target but rather to achieve best efforts from a practical and implementable standpoint. Further detail on the exfiltration trench is provided in Section 3.3. It would be proposed to incorporate LID to address water balance and reduce the volume of run-off particularly for frequent events while maintaining the 2-year design storm criteria for the local and trunk storm sewers. This would introduce redundancy into the design and increase resilience to climate change. Realigning Oatman Drain The Oatman Drain storm sewer is not fully contained within the road right-of-way with approximately 1.1 km located on private property. This creates future maintenance concerns and can lead to additional basement flooding where surcharging of the minor system occurs on private property. Realigning the Oatman Drain storm sewer to Wellington Road provides the opportunity to improve capacity to meet the City of London design standards and develop a dedicated trunk storm sewer for the Wellington Road corridor. Although the current alignment is located within private property, easements are not currently in place. Realigning Oatman Drain would remove the requirement for future easements. Upper Thames Region Conservation Authority Planning Policy UTRCA regulations stipulate that SWM facilities, with the exception of outlets, should be directed to areas located outside of the defined limits of the natural hazard, which includes the regulatory flood plain, unless it can be demonstrated that there is a net public benefit in selecting the flood plain location and if all other potentially viable locations have been dismissed. In this case, the Watson Park location is the only viable area where sufficient open space is available for the location of a

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SWM facility as the upstream catchment is fully developed. The SWM facility would provide a net benefit to water quality for the currently untreated 72 ha of the Oatman Drain and Watson Street drainage areas. The UTRCA regulations also state that the encroachment of SWM facilities in to the flood plain must be justified with a catchment scale assessment as part of a Catchment Strategy, Area Plan, Subwatershed Plan, Master Drainage Plan or Environmental Assessment Act process. In this case, the location of the SWM facility is being assessed under the current Municipal Class EA. City of London Works Yard The City of London operates a works yard within Watson Park that includes laydown areas for construction materials and snow storage areas for winter snow removal. Any proposed works within Watson Park, including a SWMF, will reduce the available area for the works yard. Development and assessment of alternatives are to have regard for the use of this area by the City. Back to the River The Back to the River design competition includes Watson Park in future planning for the South Branch of the Thames River corridor. Any proposed works within Watson Park should consider the interaction with the future use of any park for public activity and enjoyment. Increased Storm Sewer Capacity Similar to the Oatman Drain, trunk storm sewers in immediately adjacent catchment areas have capacity issues leading to historic flooding concerns. Upsizing and realigning the Oatman Drain and the Watson Street outlet provides an opportunity to redirect minor system flows from neighbouring trunk storm sewers to the Oatman Drain catchment to alleviate capacity concerns. Sizing of the Watson Park outlet considers additional catchment areas where feasible. The following table indicates some of the key aspects and their opportunities and constraints as they pertain to storm servicing and stormwater management. Table 2. Stormwater Opportunities and Constraints

Key Aspect Opportunity Constraint

Future Development / Rapid Transit

• Retrofit quantity and quality control to catchment

• PPS triggers stormwater management for infill / intensification development.

• Upsize and relocate existing storm sewers to meet minimum standards

• Potential for cost sharing with the rapid transit project

• Opportunity to introduce a Wellington Road local and trunk storm sewer servicing arrangement

• Increase in storm runoff • Existing infrastructure condition • Identified basement flooding • No water quality controls in catchment • No water balance controls in catchment

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Key Aspect Opportunity Constraint

Wellington Road Low Impact Development (LID) Options

• Soils have moderate to high hydraulic conductivity promoting infiltration

• Study are is not located within a well head protection zone

• Groundwater table is anticipated to be significantly lower than proposed LID inverts

• Meets policy directives from MOECC with respect to water balance.

• Introduces climate change resilience.

• Proposed Wellington Road cross-section constrains inclusion of LIDs within the boulevard landscape

• Wellington Road is an arterial road and major transportation corridor in London which increases potential spill contamination and sediment loading.

• Highly Vulnerable Aquifer present within the study area

Realignment of Oatman Drain

• Develop new trunk storm sewer • Remove existing storm sewers from private

properties • Reduce/alleviate basement flooding • Reduced maintenance cost • Direct flows to new outlet with scour protection

• Potential conflicts with existing watermains, sanitary sewers, and sanitary forcemain

• Capital cost • Existing grading

Outlet Location • Rationalization of the number of outlets and location of outlets for maintenance

• Reduced maintenance costs • Improve scour protection at Oatman Drain

Outlet

• Existing condition • Maintain downstream slope stability • Maintain water source to oxbow wetlands • Relocation of City Works yard • Approvals • Capital cost

Retrofitting Water Quality Controls

• Improve water quality of receiving waters • Meet provincial targets for quality control • Enhance water quality, improve downstream

ecological function

• Encroachment of City Lands • Duplication of City PPS policy to address infill

and intensification. • Approvals • Maintenance cost • Capital cost

Back to the River Design Contest

• Provide improved aesthetics in Watson Park to meet with the design objectives of the Back to the River plan

• Impacts future plans for Watson Park by removing land for SWM controls

Watson Park Works Yard

• Provide water quality treatment for existing works yard and snow storage runoff

• Reduce available land for works yard and snow storage

• May require relocation of works yard

Increased Storm Sewer Capacity

• Alleviate / reduce basement flooding in upstream catchment

• Reduce overland flow on Wellington Road and through private properties

• Alleviate capacity issues for neighbouring trunk storm sewers

• Provide capacity for future infill development and intensification

• Conflicts with existing infrastructure • Maintenance cost • Capital cost

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3.3 Preliminary Storm Servicing and Stormwater Management Alternatives

Preliminary storm servicing and stormwater management alternatives have been developed in consideration of social, economic, natural heritage and technical constraints. Storm servicing may include overland flow routes, storm sewers and/or SWMFs. Pre-screening The implementation of multiple oil grit separator (OGS) units throughout the Oatman Drain catchment to treat the various lateral storm sewers feeding the Oatman Drain trunk sewer was initially considered. The maximum catchment area for an OGS unit is typically 5 ha. Initial evaluations identified that the lateral sewers feeding the Oatman Drain trunk storm sewer range in catchment area from 2.5 ha to 8.3 ha. Based on this area each lateral sewer would require a dedicated OGS unit resulting in approximately 14 OGS units within the Oatman Drain catchment. Due to the large number of OGS units required, retrofitting the existing Oatman Drain catchment with OGS units to provide water quality control was not considered feasible and further evaluation has been screened. The following preliminary alternatives were considered. Alternative 1: Do Nothing – Replace Existing Watson Street Storm Sewer Outlet No solution would be implemented to improve stormwater servicing or water quality control for the study area and a new Watson Street outlet would be sized to convey the 2-year event for the existing Watson Street outlet drainage area. Oatman Drain will continue to discharge at the existing location. The existing 900 mm outlet would be replaced with a similar sized outlet pipe with headwall. Summary Constraints for this solution are:

• The Watson Street outlet would not provide capacity for future realignment and upsizing of the Oatman Drain trunk storm sewer;

• No provision for future widening of Wellington Road for rapid transit; • No additional capacity provided for future infill development; • No retrofitting of water quality controls to the study area would be provided in accordance

with provincial policy; and • The existing outlet provides sufficient capacity for the 2-year event, however, some upsizing

of the Watson Street storm sewer would be required.

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Alternative 2: Relocate Outlet to the Wellington Road Bridge, Realign Oatman Drain and Provide SWM Controls for Wellington Road Right-of-Way Only (OGS Units and LID Strategies) Storm servicing could be addressed via installation of a trunk storm sewer along Wellington Road to the Wellington Road bridge, installing a new outlet at the Wellington Road bridge discharging directly to the South Branch of the Thames River and abandoning the existing Watson Street, Oatman Drain and Grand Avenue outlets as part of the new trunk storm sewer upgrades. A separate local storm sewer would also be installed on Wellington Road to allow water quality control via OGS units for a widened Wellington Road right-of-way under rapid transit planning. Water quality control would only be provided to the Wellington Road corridor. No retrofitting of the existing Oatman Drain catchment would be provided and future infill development and intensification would require private permanent system (PPS) controls. Further efforts would also be made to remove the overland flow path from private property through the removal of sag locations along Wellington Road and/or the use of over-sized storm sewers to convey the 100-year event in sections of the Wellington Road South trunk storm sewer. Watson Street Outlet The Watson Street storm sewer would be abandoned and replaced with the Wellington Road South trunk storm sewer. The existing outlet would also be abandoned and a new outlet constructed at the Wellington Road bridge. The new outlet could be upsized up to a 2550 mm outlet sewer, complete with a headwall subject to detailed design. The increase in flows to the new outlet location could lead to increased erosion and scour downstream of the outlet. Energy dissipation scour bowls and backwater pools for aquatic habitat enhancement would be recommended to be integrated into the new storm outlet if appropriate and feasible. Moving the outlet away from Watson Park could starve the oxbow wetlands of base flow and lead to deterioration of these natural heritage features. Base flow could be provided through secondary low flow outlet that runs from Wellington Road, along Watson Street to the existing Watson Street outlet location. A local Wellington Road storm sewer would also be installed within the Wellington Road right-of-way. The local storm sewer would connect to the Wellington Road South trunk storm sewer at four locations:

• Intersection of Commissioners Road and Wellington Road (catchment = 3.0 ha); • Intersection of Moore Street and Wellington Road (catchment = 4.1 ha); • Intersection of Watson Street and Wellington Road (catchment = 2.2 ha); and • Intersection of Front Street and Wellington Road (catchment < 1.5 ha).

An OGS unit would be installed at each location to provide water quality control for a future widened Wellington Road right-of-way. Oatman Drain Outlet The Oatman Drain from Percy Street to the outlet at Watson Park would be abandoned and replaced with the Wellington Road South trunk storm sewer. The Oatman Drain outlet would also

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be abandoned. The new outlet location at the Wellington Road bridge would be more readily accessible for construction and maintenance than the current Oatman Drain outlet location. Grand Avenue Outlet The Grand Avenue storm sewer outlets directly to the Watson Park at the east end of Grand Avenue. The existing outlet would be abandoned and the storm sewer would instead be directed west to Wellington Street and connected to the Wellington Road South trunk storm sewer. Existing Wellington Road Bridge Outlet An existing 1500 mm storm sewer outlet is located at the Wellington Road bridge. The storm sewer services an area of approximately 14.7 ha including Wellington Road, High Street and Grand Avenue (west of Wellington Road). The existing outlet and associated storm sewer along Wellington Road would be abandoned and the system incorporated into the new Wellington Road South trunk storm sewer. Additional Drainage Areas Five external sub-catchments have been considered for addition to the Wellington Road South trunk storm sewer; P-01, P-02, P-03, P-04, P-05 as shown in Figure 5. The combined catchment area is 31.8 ha. P-01 is located south of Commissioners Road East and currently flows through the Victoria Hospital private storm sewer. Catchment P-02 is currently undeveloped land owned by London Health Sciences and flows through the Victoria Hospital private storm sewer. Under ultimate conditions it has been assumed that catchment P-02 would be fully developed as commercial or industrial land-use and a runoff coefficient of 0.9 has been applied. Catchments P-03 and P-04 are located along High Street and could be redirected along Baseline Road and Thomas Janes Drive, respectively. Catchment P-05 is located at Windsor Crescent. The minor system for P-05 could be directed down Frank Place to the Wellington Road South trunk storm sewer. Storm Servicing Preliminary trunk storm sewer sizing was determined using the City of London storm sewer design sheet. The Wellington Road South trunk storm sewer would be located fully within the Wellington Road right-of-way, and range in size from 1650 mm to 2550 mm. It is expected that the additional capacity should alleviate some basement flooding concerns where the existing storm sewer is undersized and is located on private property. Three local Wellington Road storm sewers would be installed to reduce the local sewer catchment area to a maximum of 6 ha to allow water quality treatment using OGS units. The local storm sewers would range in size from 375 mm to 825 mm. Storm sewer sizing would account for infill development within the Watson Street and Oatman Drain catchments. Infill development was assumed to be a transition from predominantly low density residential (runoff coefficient = 0.5) to a combination of low, medium and high density residential (average runoff coefficient = 0.7). For sub-catchment B-01 it was assumed that the Victoria Hospital lands would be fully developed with a high imperviousness (90 %). Sub-catchments where runoff coefficients were increased to account for the change in land use are shown in Table 3 and identified in Figure 5.

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Table 3. Sub-Catchment Existing and Proposed Runoff Coefficients

Sub-Catchment Catchment Area (ha)

Existing Runoff Coefficient

Proposed Runoff Coefficient

A-01 1.68 0.50 0.70

A-02 0.65 0.50 0.70

A-04 1.49 0.60 0.70

A-05 0.68 0.50 0.70

B-05 8.90 0.50 0.70

B-07a 3.60 0.50 0.70

B-07b 3.10 0.60 0.70

B-08 2.50 0.50 0.70

B-09 5.35 0.50 0.70

B-10 3.37 0.50 0.70

B-11 7.32 0.40 0.70

B-12 4.51 0.50 0.70

C-03 2.30 0.50 0.70

D-01 1.04 0.50 0.70

* Only catchments with a change in runoff coefficient area included. There are several sag locations along Wellington Road that create trapped low points for the overland flow path. During detailed design, further assessment should be completed to determine if the sag locations can be removed to allow overland flow to be contained within the road right-of-way or if the Wellington Road South trunk storm sewer should be upsized to provide capacity for the major system (100-year event) to alleviate ponding in these locations. Storm Water Management Controls Water quantity control is not required for catchments discharging directly to the South Branch of the Thames River due to the much longer time to peak for the South Branch of the Thames River at this location. MOE Level 2 protection (70% total suspended solids (TSS) removal) is required for the Oatman Drain / Fox Bar Creek catchment (Delcan, 2014). Water quality control would be provided for the Wellington Road local storm sewer only. Four (4) OGS units would be sized to provide MOE Level 2 protection. No additional retrofitting of water quality controls would be provided. The proposed location of OGS units is shown in Figure 5. Water quality control calculations accounted for an increase in the area of the Wellington Road pavement of 4.2 ha to account for up to 6 lanes of traffic under rapid transit planning. Low Impact Development (LID) Strategies The increase in runoff volume associated with the widening of Wellington Road would be addressed with a LID exfiltration trench. Initial flows would be directed to the exfiltration trenches comprising of perforated pipe wrapped in geotextile surrounded by gravel, and plugged at the downstream end. A conceptual arrangement of the exfiltration trench is shown in Figure 4. Flow from Wellington Road would be captured in catchbasins and conveyed through a local storm sewer to an OGS unit for pre-treatment. The OGS unit would discharge to a manhole containing an diversion arrangement

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comprised of a sump, an outlet to the trench at a lower elevation, and an outlet to a lateral storm sewer at a higher elevation. Once the capacity of the trench is exceeded, flows would be directed to the Wellington Road trunk storm sewer via the lateral outlet. Figure 4. General Arrangement for the Exfiltration Trench The sizing of the exfiltration trench and perforated pipe would be determined during detailed design and would be sized to provide best efforts in mitigating impacts to the water balance. Some key considerations in the design will include:

• Confirmation of soil and groundwater conditions. • The Wellington Road lateral and main storm sewers will be designed and sized with no

consideration for flow reduction provided by the LID (assumes exfiltration system has failed and/or abandoned);

• OGS units will provide pre-treatment to limit loading to the LID; • Appropriate spacing of catchbasins to manage drainage areas directed to the exfiltration

system; • Orientation of perforations to limit clogging; • Consideration of maintenance activities to allow flushing of the system with existing City

operational capabilities; and • Appropriate grade of perforated pipe to encourage sediment accumulation at the downstream

end for ease of maintenance. Summary Constraints for this solution are:

• Existing Wellington Road profile may require steep storm sewer pipes and / or drop structures to provide sufficient cover and grade for proposed trunk storm sewer;

• Sag locations on Wellington Road will need to be removed to provide an appropriate overland flow path for the major system without causing flooding of adjacent properties. If sag locations cannot be removed, sections of oversized pipe will be required to convey the 100-year storm;

• Upsizing of existing sewers is required to provide sufficient capacity to convey the 2-year storm;

• Potential conflicts with future rapid transit corridor; • The opportunity for both local and trunk storm sewers along Wellington Road is dependent on

the final rapid transit design and proposed cross-section; • LID opportunities are dependent on local site conditions and will be investigated during

detailed design; • Potential conflicts with the watermain, sanitary sewer and utilities along Wellington Road; • Retrofitting water quality controls to the Oatman Drain catchment area will not be provided

and no benefit to water quality will be achieved. Future water quality control for infill development would need to be addressed through PPS;

• Potential for erosion and channel instability at the outlet location to Watson Park; and

Page 16



• Potential to starve the oxbow wetlands of base flow by amalgamating the three (3) Watson Park outlets.

Alternative 3: Realign Oatman Drain and Provide SWM Controls for Wellington Road Right-of-Way Only (OGS Units and LID Strategies) Storm servicing could be addressed via the installation of a trunk storm sewer along Wellington Road to the existing outlet at Watson Street, abandoning the existing Oatman Drain and Grand Avenue outlets and upsizing and replacing the Watson Street outlet as part of the new trunk storm sewer. A separate local storm sewer would also be installed on Wellington Road with water quality control for a future widened Wellington Road right-of-way for rapid transit provided by two OGS units. Water quality control would only be provided to the Wellington Road corridor. No retrofitting of the existing Oatman Drain catchment would be provided and future infill development and intensification would require private permanent system (PPS) controls. Further efforts would also be made to remove the overland flow path from private property through the removal sag locations along Wellington Road and/or the use of over-sized storm sewers to convey the 100-year event in sections of the Wellington Road South trunk storm sewer. Watson Street Outlet The Watson Street storm sewer would be abandoned and replaced with the Wellington Road South trunk storm sewer. A new outlet will be constructed at the existing Watson Street outlet location. The new outlet could be upsized up to a 2550 mm diameter outlet sewer, complete with a headwall subject to detailed design. The increase in flows to the new outlet location could lead to increased erosion and scour downstream of the outlet. Energy dissipation scour bowls and backwater pools for aquatic habitat enhancement would be recommended to be integrated into the new storm outlet where appropriate and feasible. A local Wellington Road storm sewer would also be installed within the Wellington Road right-of-way. The local storm sewer will connect to the Wellington Road South trunk storm sewer at two (2) locations:

• Intersection of Commissioners Road and Wellington Road (catchment = 3.0 ha); • Intersection of Moore Street and Wellington Road (catchment area = 4.1 ha); and • Intersection of Watson Street and Wellington Road (catchment area = 2.2 ha).

An OGS unit would be installed at both locations to provide water quality control for a future widened Wellington Road. Oatman Drain Outlet The Oatman Drain from Percy Street to the outlet at Watson Park would be abandoned and replaced with the Wellington Road South trunk storm sewer. The Oatman Drain outlet would also be abandoned. The new outlet location at Watson Street or the Wellington Road bridge would be more readily accessible for construction and maintenance than the current Oatman Drain outlet location. Grand Avenue Outlet

Page 17



The Grand Avenue storm sewer outlets directly to the Watson Park at the east end of Grand Avenue. The existing outlet would be abandoned and the storm sewer would instead be directed west to Wellington Street and connected to the Wellington Road South trunk storm sewer. Additional Drainage Areas Five external sub-catchments have been considered for addition to the Wellington Road South trunk storm sewer; P-01, P-02, P-03, P-04, P-05 as shown in Figure 6. The combined catchment area is 31.8 ha. P-01 is located south of Commissioners Road East and currently flows through the Victoria Hospital private storm sewer. Catchment P-02 is currently undeveloped land owned by London Health Sciences and flows through the Victoria Hospital private storm sewer. Under ultimate conditions it has been assumed that catchment P-02 would be fully developed as commercial or industrial land-use and a runoff coefficient of 0.9 has been applied. Catchments P-03 and P-04 are located along High Street and could be redirected along Baseline Road and Thomas Janes Drive, respectively. Catchment P-05 is located at Windsor Crescent. The minor system for P-05 could be directed down Frank Place to the Wellington Road South trunk storm sewer. Storm Servicing Preliminary trunk storm sewer sizing was determined using the City of London storm sewer design sheet. The Wellington Road South trunk storm sewer would be located fully within the Wellington Road right-of-way, and range in size from 1650 mm to 2550 mm. It is expected that the additional capacity should alleviate some basement flooding concerns where the existing storm sewer is undersized and is located on private property. Two local Wellington Road storm sewers would be installed to reduce the catchment area to a maximum of 6 ha to allow water quality treatment using OGS units. The local storm sewers would range in size from 375 mm to 825 mm. Storm sewer sizing would account for infill development within the Watson Street and Oatman Drain catchments. Infill development was assumed to be a transition from predominantly low density residential (runoff coefficient = 0.5) to a combination of low, medium and high density residential (average runoff coefficient = 0.7). For sub-catchment B-01 it was assumed that the Victoria Hospital lands would be fully developed with a high imperviousness (90 %). Sub-catchments where runoff coefficients were increased to account for the change in land use are shown in Table 3 and identified in Figure 6. There are several sag locations along Wellington Road that create trapped low points for the overland flow path. During detailed design, further assessment should be completed to determine if the sag locations can be removed to allow overland flow to be contained within the road right-of-way or if the Wellington Road South trunk storm sewer should be upsized to provide capacity for the major system (100-year event) to alleviate ponding in these locations. Storm Water Management Controls Water quantity control is not required for catchments discharging directly to the South Branch of the Thames River due to the much longer time to peak for the South Branch of the Thames River at this location.

Page 18



MOE Level 2 protection (70% total suspended solids (TSS) removal) is required for the Oatman Drain / Fox Bar Creek catchment (Delcan, 2014). Water quality control would be provided for the Wellington Road local storm sewer only. Three OGS units would be sized to provide MOE Level 2 protection. No additional retrofitting of water quality controls would be provided. The proposed location of OGS units is shown in Figure 5. Water quality control calculations accounted for an increase in the area of the Wellington Road pavement of 4.2 ha to account for up to 6 lanes of traffic under rapid transit planning. Low Impact Development (LID) Strategies The increase in runoff volume associated with the widening of Wellington Road would be addressed with a LID exfiltration trench. Initial flows would be directed to the exfiltration trenches comprised of perforated pipe wrapped in geotextile surrounded by gravel, and plugged at the downstream end. The design of this system is consistent with Alternative 2 above. Summary Constraints for this solution are:


• Sag locations on Wellington Road will need to be removed to provide an appropriate overland flow path for the major system to prevent flooding of private property. If sag locations cannot be removed, sections of oversized pipe will be required to convey the 100-year storm;

• Upsizing of existing sewers is required to provide sufficient capacity for the 2-year storm; • Potential conflicts with future rapid transit corridor; • The opportunity for both local and trunk storm sewers along Wellington Road is dependent on

the final rapid transit design and proposed cross-section; • LID opportunities are dependent on local site conditions and will be investigated during

detailed design; • Potential conflicts with the watermain, sanitary sewer and utilities along Wellington Road; • Retrofitting water quality controls to the Oatman Drain catchment area will not be provided

and no benefit to water quality will be achieved. Future water quality control for infill development would need to be addressed through PPS;

• Potential for erosion and channel instability at the outlet location to Watson Park; and • Potential to starve the oxbow wetlands of base flow by amalgamating the three (3) Watson

Park outlets.

Page 19



Alternative 4: Realign Oatman Drain and Provide End of Pipe SWM Controls (SWMF Facility) Storm servicing could be addressed via the installation of a trunk storm sewer along Wellington Road, abandoning the existing Oatman Drain and Grand Avenue outlets and upsizing and replacing the Watson Street outlet. The major overland flow path will be moved from private property to Wellington Road and follow the general path of the trunk storm sewer. Retrofitting the existing catchment with water quality controls would be achieved through an end-of-pipe stormwater management facility (SWMF). Watson Street Outlet The Watson Street storm sewer would be abandoned and replaced with the Wellington Road South trunk storm sewer with a new outlet at the existing Watson Street outlet location. The new outlet will be upsized up to a 2550 mm outlet sewer, complete with headwall, subject to detailed design. Oatman Drain Outlet The Oatman Drain storm sewer system would be abandoned and replaced with the Wellington Road South trunk storm sewer. The Oatman Drain outlet would also be abandoned. The new outlet location at Watson Street would be more easily accessible for construction and maintenance than the current Oatman Drain outlet location. Grand Avenue Outlet The Grand Avenue storm sewer outlets directly to the Watson Park at the east end of Grand Avenue. The existing outlet would be abandoned and the storm sewer directed west to Wellington Road and connected to the Wellington Road South trunk storm sewer. Additional Drainage Areas In order to provide relief to adjacent storm sewer networks external drainage areas would be redirected to the Wellington Road South trunk storm sewer. Five external catchments have been considered for addition to the Wellington Road South trunk storm sewer; P-01, P-02, P-03, P-04, P-05 as shown in Figure 7. The total catchment area is 31.8 ha. P-01 is located south of Commissioners Road East and currently flows through the Victoria Hospital private storm sewer. Catchment P-02 is currently undeveloped land owned by London Health Sciences and flows through the Victoria Hospital private storm sewer. Under ultimate conditions it has been assumed that catchment P-02 would be fully developed as commercial or industrial land-use and a runoff coefficient of 0.9 has been applied. Catchments P-03 and P-04 are located along High Street and could be redirected along Baseline Road and Thomas Janes Drive, respectively. Catchment P-05 is located at Windsor Crescent. The Windsor Crescent minor system could be directed down Frank Place to the Wellington Road South trunk storm sewer.

Page 20



Storm Servicing Preliminary trunk storm sewer sizing was determined using the City of London storm sewer design sheet as defined in the City of London Design Specifications and Design Manual (2012). The Wellington Road South trunk storm sewer would be relocated from private property to the Wellington Road right-of-way. A 2550 mm outlet size would be required, subject to detailed design. It is anticipated that additional capacity in the trunk storm sewer and removing Oatman Drain from private property will alleviate some basement flooding concerns in the study area. Storm sewer sizing would account for infill development within the Watson Street and Oatman Drain catchments. Infill development was assumed to be a transition from predominantly low density residential (runoff coefficient = 0.5) to a combination of low, medium and high density residential (average runoff coefficient = 0.7). For sub-catchment B-01 it was assumed that the Victoria Hospital lands would be fully developed with a high imperviousness (90 %). Sub-catchments where runoff coefficients were increased to account for the change in land use are shown in Table 3 and identified in Figure 7. There are several sag locations along Wellington Road that create trapped low points for the overland flow path. During detailed design, further assessment should be completed to determine if the sag locations can be removed to allow overland flow to be contained within the road right-of-way or if the Wellington Road South trunk storm sewer should be upsized further to provide capacity for the major system (100-year event) to alleviate ponding in these locations. Storm Water Management Controls Water quantity control is not required for catchments discharging directly to the Thames because of the much longer time to peak for the South Branch of the Thames River at this location. Water balance requirements would not be met by this strategy. The proposed widening of Wellington Road would result in increased runoff volume and decreased infiltration and evapotranspiration. Under Alternative 4, water quality controls would be provided via an end-of- pipe SWMF for existing development and future road widening within the catchment. The new Wellington Road South trunk storm sewer outlet would discharge into a forebay, directing flows through a permanent pool and active storage before discharging via an outlet structure to the oxbow wetlands in Watson Park. MOE Level 2 protection (70% total suspended solids (TSS) removal) is required for the Oatman Drain / Fox Bar Creek catchment (Delcan, 2014). The MOE SWM guidelines were used to determine preliminary sizing for the SWMF volume and SWM block area. The preliminary SWMF location is shown in Figure 8. To SWMF sizing calculations accounted for a widened Wellington Road (additional 4.2 ha increase in impervious surfaces) and redirection of an additional 43.8 ha of external drainage area to the Wellington Road trunk storm sewer. The pond has not been sized for future infill development or intensification which would require permanent private systems to address water quality concerns. The permanent pool and extended detention pond volumes for each scenario are provided in Table 4.

Page 21



Table 4. Proposed Stormwater Management Facility General Design Characteristics

Characteristic Scenario

Scenario Existing Conditions Proposed Conditions

Imperviousness 69% 72%

Service Catchment Area (ha) 72 104

Level of Water Quality Protection Level 2 Level 2

Water Quality Protection Volume (m3/ha) 128.5 133.2

Total Volume Required (m3) 9,286 13,860

Required Permanent Pool and Forebay Volume (m3) 6,395 9,696

Erosion Control and Baseflow Volume (m3/ha) 40 40

Extended Detention Volume (m3) 2,892 4,164

SWM Block Size (ha) 0.75 0.97 Summary Constraints for this solution are:

• Does not address water balance requirements and will result in a change to the existing hydrologic cycle through increased runoff volume from the future widening of Wellington Road.


• Sag locations on Wellington Road will need to be removed to provide an appropriate overland flow path for the major system without causing flooding of adjacent properties. If sag locations cannot be removed, sections of oversized pipe will be required to convey the 100-year storm in the minor system;

• Upsizing of existing sewers required to provide sufficient capacity; • Potential conflicts with future rapid transit corridor; • Potential conflicts with utilities, watermain, sanitary sewer along Wellington Road; • Significant portion of the Watson Park area required for the proposed SWMF; • Location of the SWMF constrained by the woodland community within Watson Park; • Retrofitting water quality controls to the Oatman Drain catchment area would be provided for

existing development and future road widening, however, water quality control for future infill development would still need to be addressed through PPS;

• Potential to starve the oxbow wetlands of base flow by amalgamating the three (3) Watson Park outlets;

• Interaction with the Back to the River design contest and future planning; • Removal of a large portion of the current City of London works yard.

Page 22



References AECOM. (2017). City of London, 2017 Infrastructure Renewal Program, Contract 9, Base Line Road

East, Balderstone Avenue, Percy Street and Sylvan Street.

Delcan. (2014). Water Resources and Slope Stability Components for a Central Thames Subwatershed Study.

City of London (2017) Design Specifications & Requirements Manual.

City of London. (2010). Private Permanent Systems Policy.

Coulibaly et al. (2016). A comparison of future IDF curves for Southern Ontario.

Credit Valley Conservation. (2010). Low Impact Development Stormwater Management Planning and Design Guide.

Ontario Ministry of the Environment and Climate Change. (2003). Stormwater Management Planning and Design Manual. Toronto: Queen's Printer for Ontario.

Ontario Ministry of the Environment and Climate Change. (2015). Interpretation Bulletin: Expectations Re: Stormwater Management.

Ontario Ministry of the Environment and Climate Change. (2017). Thames – Sydenham & Region Drinking Water Source Protection Interactive Mapping (available at http://www.sourcewaterprotection.on.ca/approved-source-protection-plan/interactive-mapping/)

http://www.sourcewaterprotection.on.ca/approved-source-protection-plan/interactive-mapping/

http://www.sourcewaterprotection.on.ca/approved-source-protection-plan/interactive-mapping/

Appendix A

Figures

Watson Street Outlet

Oatman Drain Outlet

Grand Avenue Outlet

Wellington Road

High Street

-

South Street

Base

line R

oad E

ast

Gran

d Ave

nue

Belgrave Avenue

Ridout Street South

Fairview Avenue

Upper Queen Street

Bake

r Stre

et

Westo

n Stre

et

Bond

Stre

et

Nelson Street

Wind

sor A

venu

e

Trevithen Street

Whett

er Av

enue

Moor

e Stre

et

Rayw

ood A

venu

e

Ches

ter S

treet

Carfrae Crescent

Huntingdon Drive

Hill Street

Garfi

eld A

venu

e

Front Street

Chiddington Avenue

Comm

ission

ers R

oad E

ast

Alex

andr

a Stre

et

Rown

tree A

venu

e

Langley StreetEm

ery S

treet

East

Maitland Street

Foxb

ar Ro

ad

Thom

as Ja

nes D

rive

Westminster Avenue

Percy

Stre

et

Chev

iot R

oad

Cowan Avenue

McKeon Avenue

McCl

ary A

venu

e

Belha

ven R

oad

Compton Crescent

Connington Street

Gerrard Street

Carfrae Street

Herkimer Street

Linco

ln Pl

ace

Western Counties Road

Waterloo Street

William Street

Aver

ill Cr

esce

nt

Wilki

ns St

reet

Bellevue Avenue

Victor

ia Ho

spita

l Ent

ry

McKe

nzie

Aven

ue

Colborne Street

Highland Heights

Philip Street

Clarence Street

Lhsc

Driv

eway

Wellington Street

Southgate Street

Lyndhurst Place

Tecu

mseh

Ave

nue E

ast

Hick

son A

venu

e

St Neots Drive

Adare Crescent

Torri

ngto

n Cres

cent

Thompson Road

Kingsford Crescent

Ferg

uson

Plac

e

Sandringham Crescent

Mountsfield Drive

Wind

sor C

resc

ent

Water

man A

venu

e

Balderstone Avenue

Barons Court

Cowa

n Plac

e

Marla

Cre

scen

t

Rosel Crescent

Chiddington Gate

Cowan Court

Rockingham Court

Sylvan Street

Mountsfield Crescent

Kennon Place

Fairv

iew C

ourt

Aver

ill Pl

ace

Waterman Lane

Chidd

ingto

n Plac

e

Huntingdon Place

Wood

land P

lace

Wellin

gton C

ourt

Compton Place

Compto

n Cou

rt

Tecu

mseh

Ave

nue E

ast

-

-

Emer

y Stre

et Ea

st

-

Gerrard Street

-

-

-

-

-

-

-

Ches

ter S

treet

Wilkins Street

-

-

-

-

-

-

-

Base

line R

oad E

ast

-

-Ch

ester

Stre

et

-

Sheet No.

Scale:

Date:

Drainage and Stormwater ManagementStudy Area

Figure 1

1:7,500

1/9/2017µ

Project No. 60513238Watson StreetStorm Sewer OutletClass Environmental Assessment

Schedule BLegend

UTRCA Regulatory FloodlineStudy AreaLot Line

Watson Park

ThamesRiver (South Branch)

DUNDAS ST

WEST

DEL B

RNE

OXFORD ST E

HAMILTON RD

OXFORD ST W

HIGHBURY AVE N

ADELAIDE ST N

HWY 401 E

COMMISSIONERS RD SOUTHDALE RD W

BRADLEY AVE

WONDERLAND RD N

DRAFT

Study Area

Key Map

-

Wellington Road

High Street

Base

line R

oad E

ast

Fairview Avenue

Westo

n Stre

et

Bond

Stre

et

Trevithen Street

Gran

d Ave

nue

Wilkins Street

Whett

er Av

enue

Moor

e Stre

et

Comm

ission

ers R

oad E

ast


Ches

ter S

treet

Huntingdon Drive

Front Street

Bake

r Stre

et

Rown

tree A

venu

e

Langley Street

Emer

y Stre

et Ea

st

Chidd

ingto

n Ave

nue

Foxb

ar Ro

ad

Thom

as Ja

nes D

rive

Westminster Avenue

Percy

Stre

et

Victor

ia Ho

spita

l Ent

ry

Cowan Avenue

McKeon Avenue

McCl

ary A

venu

e

Edna Street

Compton Crescent

Lhsc

Driv

eway

Southgate Street

Lyndhurst Place

Tecu

mseh

Ave

nue E

ast

Adare CrescentFrank Place

Water

man A

venu

e

Balderstone Avenue

Watson Street

Marla Crescent-

-

-

-

-

-

Ches

ter S

treet

-

Ches

ter S

treet

-

-

-

-

-

-

-

!w B-05 8.9 0.5

!w B-11 7.3 0.4 !w

C-02 6.5 0.9

!w B-09 5.4 0.5

!w B-12 4.5 0.5

!w B-01 3.9 0.9

!w B-04 3.6 0.9

!w B-10 3.4 0.5

!w B-03 3.4 0.4

!w B-08 2.5 0.5

!w B-06 2.5 0.9

!w C-01 2.5 0.9

!w B-02 2.4 0.9

!w C-03 2.3 0.5

!w A-01 1.7 0.5!w

A-04 1.5 0.6

!w A-03 1.0 0.8!w

A-05 0.7 0.5

!w A-02 0.7 0.5 !w

B-07a 3.6 0.5

!w B-07b 3.1 0.6

1650

975

1350

900

150

250

200

825

750

375

1200

600

1830

300

1500

450

525

675

1050

1050

900

525

525

675

300

300

600

525

600

450

300

525

450

375

450

900

375

675

1050

525

300

200

300

1500

300

300

825

250

600

750

1650

750

300525

250

900

675

750

825

1650

375

900

300

750

1200

600

600

450

1200

1050

375

450

300

375

450

250

375

250

1200

300

600

450

525

375

250

750

525

450

375

250

375

675

300

450

450600

1050

375

675

300

1200

375

250

300

375

250

300

675

250

675

1650

1200

750

450

525

300

600

1200

450

1200900

900

300

450

600

750

900

825

900

1050

300

600

600

1650

1050

450

1200

375

675

675

1500

675

1650

250

250

825

300

1050

825

250

450

300

1200

1200

600

675

375

1350

750

300

750

250

82537

5

300

1200

900450

375

525

375

300

675

300

1650

375

525

375

25030

0

675

675

900

250

900

105037

5

375

300

600

450

250

300

900

300

300

1650

250

1200

1200

450

900

825

375

600

1200

300

600

300

825

375

375

975

1050

250

250

450

450

750

675

450

1200

1200

375

450

600

250

750

375

300

1350

750

300

375

525

3001650

675

600

600

1350

300 60

0

1200

300

900

375

675

825

300

375

250

900

1350

1200

450

600

450 300375

600

1350

300

525

1200

750

375

600

900

900

1650

375

250

300

975

525

250

450

300

450

600

450

750

375

825

1650

375

900

300

300 450

300 1200

450

750

1200

375

675

300

600

300

375

375

675

1050

675

250

675

300

525

375

975

300

1500

375

300

300

600

750

300

300

450

375

1200

525

300

450

600

900

450

525

600

450

1050

525

375

750

300

825

300

900

600

675

300

375

1050

1200

300

250

450

525

250

375

300

1350

375

375

300

Sheet No.

Scale:

Date:

Drainage and Stormwater ManagementExisting Minor System Drainage

Figure 2

1:6,500

12/19/2016µ

DRAFTProject No. 60513238

1.3A1

Catchment ID

Run-off CoefficientCatchment Area (ha)

0.5

Watson StreetStorm Sewer OutletClass Environmental Assessment

Schedule BLegend

UTRCA Regulatory FloodlineContour (1m)

STM OutletSTM ManholeSTM PipeLot Line

Oatman Drain Outlet Sub-Catchment

Oatman Drain Outlet, BaselineRoad Sub-Catchments

Watson Street Outlet Sub-Catchments

External Sub-Catchments

Tham

esRiv

er(So

uthBr

anch

)

Watson Park

_̂_̂

_̂

_̂

_̂

_̂ _̂

-

Wellington Road

High Street

Base

line R

oad E

ast

Fairview Avenue

Westo

n Stre

et

Bond

Stre

et

Trevithen Street

Gran

d Ave

nue

Wilki

ns St

reet

Whett

er Av

enue

Brookside Street

Moor

e Stre

et

Comm

ission

ers R

oad E

ast


Rayw

ood A

venu

e Ches

ter S

treet

Huntingdon Drive

Front Street

Bake

r Stre

et

Alex

andr

a Stre

et

Rown

tree A

venu

e

Langley Street

Emer

y Stre

et Ea

stChiddington Avenue

Foxb

ar Ro

ad

Thom

as Ja

nes D

rive

Adelaide Street South

Westminster Avenue

Percy

Stre

et

Wind

sor A

venu

e

Victor

ia Ho

spita

l Ent

ry

Cowan Avenue

McKeon Avenue

McCl

ary A

venu

e

Edna Street

Thompson Road

Compton Crescent

Connington Street Chev

iot R

oad

Herkimer Street

Linco

ln Pl

ace

Beverly Street

Aver

ill Cr

esce

nt

Lhsc

Driv

eway

Southgate Street

Lyndhurst Place

Tecu

mseh

Ave

nue E

ast

Adare Crescent

Torri

ngto

n Cres

cent

Kingsford Crescent

Frank Place

Wind

sor C

resc

ent

Terrace Street

Water

man A

venu

e

Balderstone Avenue

Watson Street

Marla

Cre

scen

t

Wellington Crescent

Cheviot Place

Chiddington GateRockingham Court

Sylvan Street

Colgr

ove P

lace

Kennon Place

Fairv

iew C

ourt

Aver

ill Pl

ace

Waterman Lane

Chidd

ingto

n Plac

e

Huntingdon Place

Wellin

gton C

ourt

-

-

-

-

-

-

Ches

ter S

treet

-

Ches

ter S

treet

-

-

-

-

-

-

-

-

Emer

y Stre

et Ea

st

Sheet No.

Scale:

Date:

Drainage and Stormwater ManagementExisting Major System Drainage

Figure 3

1:6,500

1/18/2017µ


1.3A1

Catchment ID

Run-off CoefficientCatchment Area (ha)

0.5


Schedule BLegend_̂ LowPoint

Overland Flow Path

UTRCA Regulatory Floodline

Contour (1m)

Lot Line

Major SystemCatchment

Watson Street Outlet

Oatman Drain Outlet

External Minor Systems intoOatman Drain

Tham

esRiv

er(So

uthBr

anch

)

Watson Park

kj

kj

kj

kj

!w P-04 9.1 0.9

!w B-05 8.3 0.7

!w C-02 6.4 0.9

!w P-02 5.9 0.6

!w P-03 5.7 0.6

!w P-01 5.7 0.9

!w B-12 4.4 0.7

!w B-11 6.4 0.7

!w B-01 3.8 0.7

!w B-04 3.6 0.9

!w P-05 3.1 0.5

!w B-10 3.1 0.7

!w B-09 4.8 0.7

!w B-06 2.4 0.9

!w C-01 2.5 0.9

!w B-02 2.3 0.9

!w C-03 2.3 0.7

!w B-08 2.3 0.7

!w A-01 1.5 0.7

!w L-02 4.1 0.9 !w

L-01 3.0 0.9

!w L-03 2.2 0.9

!w D-01 1.0 0.7

!w B-03 1.4 0.9

!w A-05 0.7 0.7

!w A-04 1.0 0.7

!w A-02 0.5 0.7

!w A-03 0.7 0.8

!w B-07a 3.4 0.5

!w B-07b 2.9 0.6

!w E-01 14.1 0.7

!w B-07a 3.4 0.5

!w B-07b 2.9 0.6

Sheet No.

Scale:

Date:

Drainage and Stormwater ManagementProposed Alternative 2

1:6,500

2/24/2017µ


1.3A-01

Catchment ID

Runoff CoefficientCatchment Area (ha)

0.5


Schedule B

LegendProposed Outlet

kj Proposed OGS

Wellington Road Local Storm Sewer

Proposed STM PipeUTRCA Regulatory Floodline

Wellington Road Trunk Storm SewerSub-Catchment

Existing Sub-CatchmentExisting Sub-Catchment - IncreasedRunoff CoefficientWellington Road Local Storm SewerSub-Catchment

Proposed Additional Sub-Catchment

Tham

esRiv

er(So

uthBr

anch

)

Watson Park

Figure 4

Small diameter low flow pipe to provide baseflow for oxbow wetlands

New proposed outlet

kj

kj kj

!w P-04 9.1 0.9

!w B-05 8.3 0.7

!w C-02 6.4 0.9

!w P-02 5.9 0.6

!w P-03 5.7 0.6

!w P-01 5.7 0.9

!w B-12 4.4 0.7

!w B-11 6.4 0.7

!w B-01 3.8 0.7

!w B-04 3.6 0.9

!w P-05 3.1 0.5

!w B-10 3.1 0.7

!w B-09 4.8 0.7

!w B-06 2.4 0.9

!w C-01 2.5 0.9

!w B-02 2.3 0.9

!w C-03 2.3 0.7

!w B-08 2.3 0.7

!w A-01 1.5 0.7

!w L-02 4.1 0.9 !w

L-01 3.0 0.9

!w L-03 2.2 0.9

!w D-01 1.0 0.7

!w B-03 1.4 0.9

!w A-05 0.7 0.7

!w A-04 1.0 0.7

!w A-02 0.5 0.7

!w A-03 0.7 0.8

!w B-07a 3.4 0.5

!w B-07b 2.9 0.6

Sheet No.

Scale:

Date:


1:6,500

2/24/2017µ

Project No. 60513238

1.3A-01

Catchment ID


0.5


Schedule B


kj Proposed OGS

Wellington Road Local Storm SewerProposed STM PipeContour (1m)UTRCA Regulatory Floodline

Wellington Road Trunk Storm SewerSub-Catchment

Existing Sub-CatchmentExisting Sub-Catchment - IncreasedRunoff Coefficient

Wellington Road Local Storm SewerSub-Catchment

Proposed Additional Sub-Catchment

Tham

esRiv

er(So

uthBr

anch

)

Watson Park

Figure 5

-

Wellington Road

High Street

Base

line R

oad E

ast

Fairview Avenue

Westo

n Stre

et Bond

Stre

et

Trevithen Street

Gran

d Ave

nue

Wilki

ns St

reet

Whett

er Av

enue

Brookside Street

Moor

e Stre

et

Comm

ission

ers R

oad E

ast


Rayw

ood A

venu

e Ches

ter S

treet

Huntingdon Drive

Front Street

Bake

r Stre

et

Alex

andr

a Stre

et

Rown

tree A

venu

e

Langley Street

Emer

y Stre

et Ea

stChiddington Avenue

Foxb

ar Ro

ad

Thom

as Ja

nes D

rive

Adelaide Street South

Westminster Avenue

Percy

Stre

et

Wind

sor A

venu

e

Victor

ia Ho

spita

l Ent

ry

Cowan Avenue

McKeon Avenue

McCl

ary A

venu

e

Edna Street

Thompson Road

Compton Crescent

Connington Street Chev

iot R

oad

Herkimer Street

Linco

ln Pl

ace

Beverly Street

Aver

ill Cr

esce

nt

Lhsc

Driv

eway

Southgate Street

Lyndhurst Place

Tecu

mseh

Ave

nue E

ast

Adare Crescent

Torri

ngto

n Cres

cent

Kingsford Crescent

Frank Place

Wind

sor C

resc

ent

Terrace Street

Water

man A

venu

e

Watson Street

Marla

Cre

scen

t

Wellington Crescent

Cheviot Place

Chiddington GateRockingham Court

Kennon Place

Fairv

iew C

ourt

Aver

ill Pl

ace

Chidd

ingto

n Plac

e

Huntingdon Place

-

-

-

-

-

-

Ches

ter S

treet

-

Ches

ter S

treet

-

-

-

-

-

-

-

-

Emer

y Stre

et Ea

st

!w P-04 9.2 0.9

!w B-05 8.9 0.7

!w P-01 8.2 0.9

!w B-11 7.3 0.7

!w C-02 6.5 0.9

!w P-02 5.9 0.6!w

P-02 5.7 0.6

!w B-09 5.4 0.7!w

B-12 4.5 0.7

!w B-01 3.9 0.7

!w B-04 3.6 0.9

!w B-10 3.4 0.7

!w P-03 3.1 0.5

!w B-08 2.5 0.7

!w B-06 2.5 0.9

!w C-01 2.5 0.9

!w B-02 2.4 0.9

!w C-03 2.3 0.7

!w A-01 1.7 0.7

!w B-03 3.4 0.9

!w A-04 1.5 0.7

!w A-03 1.0 0.8!w

D-01 1.0 0.7

!w A-05 0.7 0.7

!w A-02 0.7 0.7

!w B-07a 3.6 0.7

!w B-07b 3.1 0.6

Sheet No.

Scale:

Date:


Figure 6

1:6,500

2/24/2017µ


1.3A-01

Catchment ID


0.5


Schedule B

LegendProposed OutletContour (1m)Proposed STM PipeUTRCA Regulatory FloodlineApproximate Pond Location

Wellington Road Trunk StormSewer Sub-Catchment

Existing Sub-CatchmentProposed Additional Sub-CatchmentsExisting Sub-Catchment - RunoffCoefficient Increased for FuturePotential Infill Development

Tham

esRiv

er(So

uthBr

anch

)

Watson Park

!@

234.5

236.5

237.2

188 m

45 m

239

240

241

242

244

245

246

247

236

249

237

235

238

243

250

238243

244

243

246

239

239

243

238 238

246

236

250

238

238

246

241

239

247

238

242

238

237

242

242

250

250

243

239

250

238

243

243

235

242

243

235

243

243

239

239

236

245245

243

249

237

243

242

242

245

236

235

235

243

244 249

238

243

FOD4

FOD4

SWD3

CUM1-1

MAM2-2

750

250

525

375

600

675

900

1200

1200

1200

1200600

900

600

600

600

600

600

1200

1200

600

1200

1200

1200

900

Sheet No.

Scale:

Date:

Drainage and Stormwater ManagementAlternative 4 - SWM Facility Option 1

Figure 7

1:1,500

1/18/2017µ

DRAFTProject No. 60513238Watson StreetStorm Sewer Outlet

Class Environmental AssessmentSchedule B


Existing STM ManholeProposed STM PipeExisting STM PipeContour (1m)UTRCA Regulatory FloodlineProposed Access Road

!@ Outlet Structure

Permanent PoolExtended Detention7.5 m Buffer

ELCCUM1-1FOD4MAM2-2SWD3

Buffers10m20m30m

Existing Watson Street Outlet Elevation 233.96

New 2400 mm OutletInvert 236.50

Existing Drop StructurePipe Invert 236.55

Outlet Structure with OrificeDischarge to Oxbow

Existing Oatman Drain OutletTo Be Removed

Maintain 900 mm Culvert

Pond location is preliminary only and could be relocated to the north sideof Watson Park.

The proposed pond outlet could alsobe relocated, however, a base flowto the southern oxbow wetland shouldbe maintained.

Appendix B

Design Calculations

RUNOFF COEFFICIENT 'C'DENSELY BUILT, PAVED - 0.90 PROJECT

SINGLE FAMILY RESIDENTIAL - 0.35 to 0.75

SEMI-DETACHED RESIDENTIAL - 0.40 to 0.75 PROJECT NO. 60311566

APARTMENTS & COMMERCIAL - 0.50 to 0.70 STORM AREA 72.29 ha

INDUSTRIAL - 0.50 to 0.90 DESIGNED BY ATS

PLAYGROUNDS & PARKS - 0.20 CHECKED BY CJM

DATE 02/28/17

FLOW, Q = 2.78 AIR

WHERE, Q = PEAK FLOW IN LITRES PER SECOND (L/s)

R = RUNOFF COEFFICIENT (See Above)

i = RAINFALL INTENSITY (mm/hr), RETURN PERIOD = 2 years

A = AREA IN HECTARES (ha)

SEWER LOCATION AREA A X C RAINFALL INTENSITY Q SEWER DESIGN

AREA STREET TOT. RUNOFF INCR TOTAL TOTAL CUM. SEWER TIME ENT. INTENSITY "n" CALC. NOM. STORM CAPACITY VELOCITY LENGTH FLOW

NO. AREA AREA COEFF. AxC SECT. AxC LAT. (2.78 x) SECT. ACCUM. 'i' PIPE D PIPE D SLOPE Q m./s. TIME

ha. ha. (above) A X R A X R A x R min. min. mm/hr l/s mm mm % l/s (min. 0.9 m/s) m minutes

WATSON STREET

A-01 WELLINGTON RD. 1.68 1.68 0.50 0.84 2.34 19.00 76.00 177.48 0.013 288.5 375 4.15 372.67 3.37 85.0 0.42

A-02 WELLINGTON RD. 0.65 2.33 0.50 0.33 0.84 3.24 0.42 19.42 75.02 242.96 0.013 349.4 525 2.80 750.84 3.47 91.7 0.44

A-03 WELLINGTON RD. 1.00 3.33 0.80 0.80 1.17 5.46 0.44 19.86 74.01 404.28 0.013 484.2 600 1.36 747.11 2.64 58.5 0.37

A-04 WELLINGTON RD. 1.49 4.82 0.60 0.89 1.97 7.95 0.37 20.23 73.18 581.64 0.013 625.3 650 0.72 672.95 2.03 92.0 0.76

A-05 WELLINGTON RD. 0.68 5.50 0.50 0.34 2.86 8.89 0.76 20.99 71.54 636.24 0.013 506.9 675 2.64 1425.03 3.98 44.2 0.18

OATMAN DRAIN

B-03 WELLINGTON RD. 3.40 3.40 0.90 3.06 8.51 10.50 103.02 876.38 0.013 569.1 1350 2.70 9150.64 6.39 247.0 0.64

B-01 LHS WELLINGTON RD. 3.90 3.90 0.90 3.51 9.76 0.44 10.50 103.02 1005.26 0.013 597.9 375 2.73 302.26 2.74 250.0 1.52

B-02 BASELINE RD. E 2.40 6.30 0.90 2.16 3.51 15.76 1.52 12.02 96.93 1527.86 0.013 707.5 450 2.57 476.88 3.00 215.0 1.20

C-01 645 WELLINGTON RD. 2.50 2.50 0.90 2.25 6.26 10.50 103.02 50.00 0.013 170.8 300 5.40 234.46 3.32 110.0 0.55

C-02 387 - 401 WELLINGTON RD. 6.50 9.00 0.90 5.85 2.25 22.52 10.50 103.02 200.00 0.013 394.0 450 1.00 297.47 1.87 802.0 7.15

C-03 BASELINE RD. 2.30 11.30 0.50 1.15 3.20 19.00 76.00 442.98 0.013 180.0 950 0.74 1876.83 2.65 60.0 0.38

B-04 WELLINGTON RD. 3.60 24.60 0.90 3.24 3.06 6.82 36.47 0.64 11.14 100.36 3660.44 0.013 1039.1 1350 1.90 7676.20 5.36 60.8 0.19

B-05 PERCY ST. 8.90 33.50 0.50 4.45 13.12 48.84 0.19 11.33 99.60 4865.02 0.013 1174.0 1350 1.75 7366.96 5.15 284.8 0.92

B-06 ROWNTREE AVE. 2.50 36.00 0.90 2.25 17.57 55.10 0.92 12.26 96.06 5292.79 0.013 1214.3 450 1.73 391.26 2.46 36.1 0.24

B-07a WELLINGTON CRT. 3.60 39.60 0.50 1.80 19.82 60.10 0.24 12.50 95.16 5719.39 0.013 1001.0 525 5.66 1067.53 4.93 20.0 0.07

B-07b CHESTER ST. 3.10 42.70 0.60 1.86 21.62 65.27 0.07 12.57 94.91 6195.39 0.013 1031.5 525 5.66 1067.53 4.93 20.0 0.07

B-08 THOMAS JANES DR. 2.50 45.20 0.50 1.25 23.48 68.75 0.07 12.63 94.67 6508.40 0.013 1471.2 900 0.94 1831.29 2.88 184.9 1.07

B-09 EMERY ST. E. 5.35 50.55 0.50 2.68 24.73 76.19 1.07 13.71 90.95 6928.91 0.013 1483.3 1050 1.02 2877.52 3.32 97.3 0.49

B-10 MOORE ST. 3.37 53.92 0.50 1.69 27.41 80.87 0.49 14.19 89.34 7225.10 0.013 1549.0 1200 0.88 3815.96 3.37 349.8 1.73

B-11 BOND ST. 7.32 61.24 0.40 2.93 29.09 89.01 1.73 15.92 84.07 7482.74 0.013 1336.9 1200 2.07 5852.59 5.17 141.0 0.45

B-12 WESTON ST. 4.51 65.75 0.50 2.26 32.02 95.28 0.45 16.38 82.78 7886.87 0.013 1429.4 1200 1.61 5161.50 4.56 308.0 1.12

GRAND AVENUE

D-01 GRAND AVE. 1.04 1.04 0.50 0.52 1.45 19.00 76.00 109.87 0.013 373.7 600 0.40 405.18 1.43 91.7 1.07

STORM SEWER DESIGN SHEET

(2 year Return Period)

2016 WATSON STREET STORM SEWER REPLACEMENT

City of London

2016 Watson Park Environmental Assessment

Existing Conditions







DATE 02/28/17

FLOW, Q = 2.78 AIR









OATMAN DRAIN / WATSON PARK

P-01 WELLINGTON RD. 5.65 5.65 0.90 5.09 14.14 10.50 103.02 1456.34 0.013 728.4 900 2.00 2671.21 4.20 250.0 0.99

P-04 LHS - BASELINE RD. 9.12 9.12 0.90 8.21 22.82 10.50 103.02 2350.77 0.013 910.0 1050 1.59 3592.66 4.15 140.0 0.56

PIPE ONLY WELLINGTON RD. 14.77 13.29 36.95 0.73 11.23 100.03 3696.39 0.013 1176.3 1350 1.00 5568.90 3.89 133.0 0.57

B-03 WELLINGTON RD. 1.42 16.19 0.90 1.28 13.29 40.51 0.57 11.80 97.79 3961.22 0.013 1118.8 1350 1.50 6820.48 4.76 247.0 0.86

L-01 WELLINGTON RD. LOCAL 3.01 3.01 0.99 2.98 8.28 0.86 10.50 103.02 853.44 0.013 629.2 675 1.50 1074.16 3.00 250.0 1.39

B-01 LHS WELLINGTON RD. 3.84 3.84 0.90 3.46 9.61 10.50 103.02 989.80 0.013 594.5 675 2.73 1449.12 4.05 250.0 1.03

B-02 BASELINE RD. E 2.32 6.16 0.90 2.09 3.46 15.41 1.03 11.53 98.83 1523.17 0.013 960.6 1050 0.50 2014.66 2.33 215.0 1.54

C-01 645 WELLINGTON RD. 2.49 2.49 0.90 2.24 6.23 10.50 103.02 50.00 0.013 170.8 300 5.40 234.46 3.32 110.0 0.55

C-02 387 - 401 WELLINGTON RD. 6.44 8.93 0.90 5.80 2.24 22.34 10.50 103.02 200.00 0.013 394.0 450 1.00 297.47 1.87 802.0 7.15

C-03 BASELINE RD. 2.31 11.24 0.70 1.62 4.50 19.00 76.00 541.66 0.013 180.0 950 0.74 1876.83 2.65 60.0 0.38

B-04 WELLINGTON RD. 3.58 37.17 0.70 2.51 14.57 10.14 75.67 0.86 12.66 94.58 7356.16 0.013 1522.6 1650 1.00 9509.77 4.45 115.0 0.43

P-02 HIGH ST. to BASELINE RD. 5.86 5.86 0.60 3.52 9.77 19.00 76.00 742.89 0.013 571.4 675 1.90 1208.93 3.38 200.0 0.99

B-05 PERCY ST. 8.27 51.30 0.70 5.79 27.22 3.52 101.53 0.43 13.09 93.05 9647.37 0.013 1685.5 1800 1.00 11993.32 4.71 46.8 0.17

B-06 ROWNTREE AVE. 2.44 53.74 0.90 2.20 36.52 107.64 0.17 13.26 92.47 10153.53 0.013 1718.2 1800 1.00 11993.32 4.71 110.0 0.39


B-07b CHESTER ST. 2.94 60.11 0.70 2.06 41.12 120.03 0.09 13.73 90.85 11105.22 0.013 1776.9 1950 1.00 14846.99 4.97 70.0 0.23

P-03 HIGH ST. to THOMAS JANES DR.5.67 5.67 0.70 3.97 11.03 19.00 76.00 838.61 0.013 674.4 825 1.00 1497.69 2.80 165.0 0.98

B-08 THOMAS JANES DR. 2.33 68.11 0.70 1.63 43.18 3.97 135.60 0.23 13.97 90.07 12414.18 0.013 1852.7 1950 1.00 14846.99 4.97 98.0 0.33

B-09 EMERY ST. E. 4.76 72.87 0.70 3.33 48.78 144.87 0.33 14.30 89.01 13093.93 0.013 1890.1 1950 1.00 14846.99 4.97 100.0 0.34

L-01 WELLINGTON RD. LOCAL 4.09 4.09 0.99 4.05 11.26 10.00 105.18 1184.00 0.013 767.5 825 1.00 1497.69 2.80 600.0 3.57

B-10 MOORE ST. 3.06 80.02 0.70 2.14 52.11 4.05 162.08 0.34 14.63 87.94 14453.31 0.013 1961.4 2100 1.00 18091.07 5.22 100.0 0.32

B-11 BOND ST. 6.36 86.38 0.70 4.45 58.30 174.45 0.32 14.95 86.95 15368.84 0.013 2007.1 2100 1.00 18091.07 5.22 320.0 1.02

P-05 WINDSOR CRES. 3.12 89.50 0.70 2.18 62.75 180.52 1.02 15.97 83.92 15349.20 0.013 2006.2 2100 1.00 18091.07 5.22 50.0 0.16

A-01 WELLINGTON RD. 1.50 91.00 0.70 1.05 64.94 183.44 0.16 16.13 83.46 15510.53 0.013 2014.0 2100 1.00 18091.07 5.22 55.0 0.18

B-12 WESTON ST. 4.38 95.38 0.70 3.07 65.99 191.97 0.18 16.31 82.97 16126.69 0.013 2043.7 2100 1.00 18091.07 5.22 30.0 0.10

A-02 WELLINGTON RD. 0.46 95.84 0.70 0.32 69.05 192.86 0.10 16.40 82.70 16149.23 0.013 2044.8 2100 1.00 18091.07 5.22 30.0 0.10

A-03 WELLINGTON RD. 0.73 96.57 0.80 0.58 69.38 194.49 0.10 16.50 82.43 16231.64 0.013 2048.7 2100 1.00 18091.07 5.22 80.0 0.26


D-01 GRAND AVE. 1.03 1.03 0.70 0.72 2.00 19.00 76.00 152.34 0.013 355.7 375 1.00 182.93 1.66 276.0 2.78

A-04 + A05 WATSON ST. 1.01 100.83 0.70 0.71 69.96 0.72 198.46 0.26 16.75 81.73 16419.37 0.013 2443.2 2550 0.40 19202.15 3.76 120.0 0.53

E-01 WELLINGTON RD. 0.68 101.51 0.70 0.48 71.39 199.78 0.53 17.29 80.30 16242.07 0.013 2433.3 2550 0.40 19202.15 3.76 60.0 0.27

Orange cells denote runoff coefficients increased from existing conditions




City of London


Alternative 2







DATE 02/28/17

FLOW, Q = 2.78 AIR










P-01 WELLINGTON RD. 5.65 5.65 0.90 5.09 14.14 10.50 103.02 1456.34 0.013 728.4 900 2.00 2671.21 4.20 250.0 0.99

P-04 LHS - BASELINE RD. 9.12 9.12 0.90 8.21 22.82 10.50 103.02 2350.77 0.013 910.0 1050 1.59 3592.66 4.15 140.0 0.56

PIPE ONLY WELLINGTON RD. 14.77 13.29 36.95 0.73 11.23 100.03 3696.39 0.013 1176.3 1350 1.00 5568.90 3.89 133.0 0.57

B-03 WELLINGTON RD. 1.42 16.19 0.90 1.28 13.29 40.51 0.57 11.80 97.79 3961.22 0.013 1118.8 1350 1.50 6820.48 4.76 247.0 0.86

L-01 WELLINGTON RD. LOCAL 3.01 3.01 0.99 2.98 8.28 0.86 10.50 103.02 853.44 0.013 629.2 675 1.50 1074.16 3.00 250.0 1.39


B-02 BASELINE RD. E 2.32 6.16 0.90 2.09 3.46 15.41 1.03 11.53 98.83 1523.17 0.013 960.6 1050 0.50 2014.66 2.33 215.0 1.54

C-01 645 WELLINGTON RD. 2.49 2.49 0.90 2.24 6.23 10.50 103.02 50.00 0.013 170.8 300 5.40 234.46 3.32 110.0 0.55

C-02 387 - 401 WELLINGTON RD. 6.44 8.93 0.90 5.80 2.24 22.34 10.50 103.02 200.00 0.013 394.0 450 1.00 297.47 1.87 802.0 7.15

C-03 BASELINE RD. 2.31 11.24 0.70 1.62 4.50 19.00 76.00 541.66 0.013 180.0 950 0.74 1876.83 2.65 60.0 0.38

B-04 WELLINGTON RD. 3.58 40.18 0.90 3.22 14.57 10.14 77.66 0.86 12.66 94.58 7544.42 0.013 1537.1 1650 1.00 9509.77 4.45 115.0 0.43


B-05 PERCY ST. 8.27 54.31 0.70 5.79 27.93 3.52 103.52 0.43 13.09 93.05 9832.58 0.013 1697.6 1800 1.00 11993.32 4.71 46.8 0.17

B-06 ROWNTREE AVE. 2.44 56.75 0.90 2.20 37.24 109.63 0.17 13.26 92.47 10337.59 0.013 1729.8 1800 1.00 11993.32 4.71 110.0 0.39


B-07b CHESTER ST. 2.94 63.12 0.70 2.06 41.84 122.03 0.09 13.73 90.85 11286.06 0.013 1787.7 1950 1.00 14846.99 4.97 70.0 0.23


B-08 THOMAS JANES DR. 2.33 71.12 0.70 1.63 43.89 3.40 136.02 0.23 13.97 90.07 12451.49 0.013 1854.8 1950 1.00 14846.99 4.97 98.0 0.33

B-09 EMERY ST. E. 4.76 75.88 0.70 3.33 48.93 145.28 0.33 14.30 89.01 13130.80 0.013 1892.1 1950 1.00 14846.99 4.97 100.0 0.34


B-10 MOORE ST. 3.06 83.03 0.70 2.14 52.26 4.05 162.49 0.34 14.63 87.94 14489.73 0.013 1963.3 2100 1.00 18091.07 5.22 100.0 0.32

B-11 BOND ST. 6.36 89.39 0.70 4.45 58.45 174.87 0.32 14.95 86.95 15404.86 0.013 2008.9 2100 1.00 18091.07 5.22 320.0 1.02

P-05 WINDSOR CRES. 3.12 92.51 0.70 2.18 62.90 180.94 1.02 15.97 83.92 15383.96 0.013 2007.9 2100 1.00 18091.07 5.22 50.0 0.16

A-01 WELLINGTON RD. 1.50 94.01 0.70 1.05 65.09 183.86 0.16 16.13 83.46 15545.10 0.013 2015.7 2100 1.00 18091.07 5.22 55.0 0.18

B-12 WESTON ST. 4.38 98.39 0.70 3.07 66.14 192.38 0.18 16.31 82.97 16161.05 0.013 2045.3 2100 1.00 18091.07 5.22 30.0 0.10

A-02 WELLINGTON RD. 0.46 98.85 0.70 0.32 69.20 193.28 0.10 16.40 82.70 16183.48 0.013 2046.4 2100 1.00 18091.07 5.22 30.0 0.10

A-03 WELLINGTON RD. 0.73 99.58 0.70 0.51 69.52 194.70 0.10 16.50 82.43 16249.06 0.013 2049.5 2100 1.00 18091.07 5.22 80.0 0.26


D-01 GRAND AVE. 1.03 1.03 0.70 0.72 2.00 19.00 76.00 152.34 0.013 355.7 375 1.00 182.93 1.66 276.0 2.78

A-04 WATSON ST. 1.01 103.84 0.70 0.71 70.04 0.72 198.67 0.26 16.75 81.73 16436.64 0.013 2444.2 2550 0.40 19202.15 3.76 120.0 0.53

A-05 WATSON ST. 0.68 104.52 0.70 0.48 71.46 199.99 0.53 17.29 80.30 16259.04 0.013 2434.2 2550 0.40 19202.15 3.76 60.0 0.27





City of London


Alternative 3







DATE 02/28/17

FLOW, Q = 2.78 AIR










P-01 WELLINGTON RD. 8.20 8.20 0.90 7.38 20.52 10.50 103.02 2113.63 0.013 837.6 900 2.00 2671.21 4.20 250.0 0.99

P-04 LHS - BASELINE RD. 9.20 9.20 0.90 8.28 23.02 10.50 103.02 2371.39 0.013 913.0 1050 1.59 3592.66 4.15 140.0 0.56

PIPE ONLY WELLINGTON RD. 0.00 17.40 7.38 8.28 43.53 0.76 11.26 99.87 4347.94 0.013 1250.1 1350 1.00 5568.90 3.89 133.0 0.57

B-03 WELLINGTON RD. 3.40 20.80 0.90 3.06 15.66 52.04 0.57 11.83 97.64 5081.54 0.013 1228.3 1350 1.50 6820.48 4.76 247.0 0.86


B-02 BASELINE RD. E 2.40 6.30 0.90 2.16 3.51 15.76 1.03 11.53 98.83 1557.79 0.013 968.8 1050 0.50 2014.66 2.33 215.0 1.54

C-01 645 WELLINGTON RD. 2.50 2.50 0.90 2.25 6.26 10.50 103.02 50.00 0.013 170.8 300 5.40 234.46 3.32 110.0 0.55

C-02 387 - 401 WELLINGTON RD. 6.50 9.00 0.90 5.85 2.25 22.52 10.50 103.02 200.00 0.013 394.0 450 1.00 297.47 1.87 802.0 7.15

C-03 BASELINE RD. 2.30 11.30 0.70 1.61 4.48 19.00 76.00 540.18 0.013 180.0 950 0.74 1876.83 2.65 60.0 0.38

B-04 WELLINGTON RD. 3.60 42.00 0.90 3.24 18.72 5.12 75.28 0.86 12.70 94.44 7309.57 0.013 1519.0 1650 1.00 9509.77 4.45 115.0 0.43


B-05 PERCY ST. 8.90 56.50 0.70 6.23 27.08 3.36 101.94 0.43 13.13 92.91 9671.85 0.013 1687.1 1800 1.00 11993.32 4.71 46.8 0.17

B-06 ROWNTREE AVE. 2.50 59.00 0.90 2.25 36.67 108.20 0.17 13.30 92.34 10190.99 0.013 1720.5 1800 1.00 11993.32 4.71 110.0 0.39


B-07b CHESTER ST. 3.10 65.70 0.70 2.17 41.44 121.24 0.09 13.77 90.72 11198.93 0.013 1782.5 1800 1.00 11993.32 4.71 70.0 0.25


B-08 THOMAS JANES DR. 2.50 73.90 0.70 1.75 43.61 3.42 135.61 0.25 14.02 89.91 12392.02 0.013 1851.5 1950 1.00 14846.99 4.97 98.0 0.33

B-09 EMERY ST. E. 5.35 79.25 0.70 3.75 48.78 146.02 0.33 14.35 88.84 13172.76 0.013 1894.4 1950 1.00 14846.99 4.97 100.0 0.34

B-10 MOORE ST. 3.37 82.62 0.70 2.36 52.53 152.58 0.34 14.68 87.78 13593.53 0.013 1916.8 2100 1.00 18091.07 5.22 100.0 0.32

B-11 BOND ST. 7.32 89.94 0.70 5.12 54.88 166.82 0.32 15.00 86.79 14679.21 0.013 1972.9 2100 1.00 18091.07 5.22 320.0 1.02

P-05 WINDSOR CRES. 3.10 93.04 0.70 2.17 60.01 172.85 1.02 16.02 83.77 14680.27 0.013 1972.9 2100 1.00 18091.07 5.22 50.0 0.16

A-01 WELLINGTON RD. 1.68 94.72 0.70 1.18 62.18 176.12 0.16 16.18 83.32 14874.11 0.013 1982.7 2100 1.00 18091.07 5.22 55.0 0.18

B-12 WESTON ST. 4.51 99.23 0.70 3.16 63.35 184.90 0.18 16.36 82.82 15513.92 0.013 2014.2 2400 1.00 25829.11 5.71 30.0 0.09

A-02 WELLINGTON RD. 0.65 99.88 0.70 0.46 66.51 186.17 0.09 16.45 82.58 15573.14 0.013 2017.1 2400 1.00 25829.11 5.71 30.0 0.09

A-03 WELLINGTON RD. 1.00 100.88 0.80 0.80 66.97 188.39 0.09 16.53 82.33 15710.97 0.013 2023.8 2400 1.00 25829.11 5.71 80.0 0.23

D-01 GRAND AVE. 1.04 1.04 0.70 0.73 2.02 19.00 76.00 153.82 0.013 357.0 400 1.00 217.29 1.73 276.0 2.66

A-04 WATSON ST. 1.49 103.41 0.70 1.04 67.77 0.73 193.31 0.23 16.77 81.69 15992.20 0.013 2419.2 2550 0.40 19202.15 3.76 120.0 0.53

A-05 WATSON ST. 0.68 104.09 0.70 0.48 69.54 194.64 0.53 17.30 80.26 15822.43 0.013 2409.5 2550 0.40 19202.15 3.76 60.0 0.27





City of London


Alternative 4

Existing Conditions Proposed Conditions

Existing Imperviousness Wellington Road WideningAdditional Area = 0 ha Additional Area = 43.84 ha

No Change in Imperviousness 3.5 % Increased Imperviousness

Water Quality Requirement (Level 2 - Normal)

70% TSS Removal (Central Thames Subwatershed Study)

70% TSS Removal (Central Thames Subwatershed Study)

Catchment Area 72.29 104.09

Runoff Coefficient (Weighted Average) 0.8 0.8

Percent Impervious % 68.8 72.4

Increase in Imperviousness % 0.00 3.5

Total Storage Volume Required m39286 13860

Extended Detention Volume Required m32892 4164

Permanent Pool Volume Required m36395 9696

Normal Protection m3/ha 128.5 133.2

Extended Detention m3/ha 40 40

Sediment ForebayForebay Length m 45 45

Forebay Bottom Width m 6 6

Side Slopes m/m 4 4

Forebay Top Width m 22 22

Forebay Width Check OK OK

Cross-section Area m227.3 27.3

Volume in Forebay m31226 1226

Percent of Permanent Pool Volume % 19.2 12.6

Permanent Pool Volume Check OK

Main CellPermanent PoolRequired Volume m3

5169 8470

Average Depth m 1.8 2.0

Side Slope m/m 3 3

Main Cell Length m 120 143

Length to Width Ratio m/m 4 4

Top Width m 30 36

Bottom Width m 19 24

Actual Volume m35314 8509

Permanent Pool Volume Check OK OK

Extended DetentionRequired Volume m3

2892 4164

Average Depth m 0.8 0.8

Side Slope m/m 7 7

Main Cell Length m 120 143

Length to Width Ratio m/m 3.0 3.1

Top Width m 41 46

Bottom Width m 30 36

Extended Detention Volumne m33173 4397

Extended Detention Volumne Check OK OK

SWM BlockBuffer m 7.5 7.5

SWM Block Area ha 0.75 0.97Total Length m 165 188

Parameter Units

Land Use SummaryExisting Conditions

Catchment Commercial Low Res Medium Res Road Parks Total Boulevard Actual AreaArea Weighted

ImperviousnessImperviousness 90 55 70 99 0 50

A-01 0.17 0.81 0.32 0.20 1.50 0.18 1.68 66.2A-02 0.03 0.28 0.16 0.14 0.60 0.05 0.65 69.1A-03 0.62 0.12 0.13 0.87 0.13 1.00 81.9A-04 0.34 0.74 0.30 1.38 0.11 1.49 71.5A-05 0.57 0.05 0.63 0.05 0.68 57.9B-01 0.10 3.78 0.00 3.89 0.05 3.94 55.9B-02 1.13 0.21 0.78 2.12 0.27 2.39 85.4B-03 1.22 0.42 1.48 3.12 0.48 3.60 84.3B-04 3.61 3.61 0.01 3.62 89.9B-05 0.84 2.20 0.65 3.69 0.43 4.12 68.5B-06 0.15 1.77 0.24 2.16 0.32 2.48 60.8B-07 0.57 1.79 0.36 2.72 0.42 3.14 65.7B-08 0.37 1.44 0.06 0.29 2.16 0.34 2.50 65.0B-09 0.33 3.90 0.06 0.58 4.87 0.48 5.35 61.6B-10 2.44 0.15 0.40 2.99 0.38 3.37 60.3B-11 0.55 3.86 0.22 0.96 0.69 6.29 1.03 7.32 57.9B-12 0.17 3.35 0.00 0.43 0.25 4.21 0.30 4.51 57.1C-01 1.92 0.00 0.40 2.32 0.19 2.51 88.4C-02 5.96 0.39 6.35 0.05 6.40 87.6C-03 3.03 5.10 0.10 0.84 0.64 9.71 0.94 10.65 64.8D-01 0.73 0.14 0.02 0.89 0.15 1.04 59.0

68.8

Proposed Conditions


ImperviousnessImperviousness 90 55 70 99 0 50

A-01 0.17 0.81 0.32 0.20 1.50 0.18 1.68 66.2A-02 0.03 0.28 0.16 0.14 0.60 0.05 0.65 69.1A-03 0.62 0.12 0.13 0.87 0.13 1.00 81.9A-04 0.34 0.74 0.30 1.38 0.11 1.49 71.5A-05 0.57 0.05 0.63 0.05 0.68 57.9B-01 0.10 3.78 0.00 3.89 0.05 3.94 55.9B-02 1.13 0.21 0.78 2.12 0.27 2.39 85.4B-03 1.22 0.42 1.48 3.12 0.48 3.60 84.3B-04 3.61 3.61 0.01 3.62 89.9B-05 1.00 6 0.1 1.2 0.06 8.36 0.54 8.90 64.4B-06 0.15 1.77 0.24 2.16 0.32 2.48 60.8B-07a 3.03 0.20 3.23 0.37 3.60 56.9B-07b 0.57 1.79 0.36 2.72 0.42 3.14 65.7B-08 0.37 1.44 0.06 0.29 2.16 0.34 2.50 65.0B-09 0.33 3.90 0.06 0.58 4.87 0.48 5.35 61.6B-10 2.44 0.15 0.40 2.99 0.38 3.37 60.3B-11 0.55 3.86 0.22 0.96 0.69 6.29 1.03 7.32 57.9B-12 0.17 3.35 0.00 0.43 0.25 4.21 0.30 4.51 57.1C-01 1.92 0.00 0.40 2.32 0.19 2.51 88.4C-02 5.96 0.39 6.35 0.05 6.40 87.6C-03 0.30 1.60 0.3 2.20 0.10 2.30 65.1D-01 0.73 0.14 0.02 0.89 0.15 1.04 59.0

Additional CatchmentsP-01 5.43 0.04 1.83 7.30 0.94 8.24 87.3P-02 7.66 0.00 0.00 0.55 0.00 8.21 0.99 9.20 86.2

P-03 & P-04 0.64 7.55 0.37 1.55 0.00 10.11 1.59 11.70 62.5P-05 0.00 2.17 0.00 0.42 0.00 2.59 0.51 3.10 60.1

104.71 70.4Increase in Total Imperviousness


ImperviousnessExisting

Imperviousness 32.29 47.01 1.44 12.92 1.03 10.02 104.71 70.4

Wellington Road Widenening 32.29 47.01 1.44 17.10 1.03 5.84 104.71 72.4

Weighted Average