UPDATED FUNCTIONAL SERVICING and STORMWATER MANAGEMENT REPORT

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1 TRAFALGAR ENGINEERING LTD. #1-481 Morden Road Oakville Ontario L6K 3W6 UPDATED FUNCTIONAL SERVICING and STORMWATER MANAGEMENT REPORT Fernbrook Homes (Bronte 15) Limited 3059/3047 Lakeshore Road West TOWN OF OAKVILLE PREPARED BY TRAFALGAR ENGINEERING LTD. PROJECT: 1448 September 14, 2012 Tel: (905) Fax: (905)

2 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: INTRODUCTION 1.1 Background In February 2008 Planning & Engineering Initiatives Ltd. prepared a Functional Servicing Report of the proposed development to be located at 3047 Lakeshore Road West, Oakville. The original report was prepared in support of an official plan and rezoning application for a 24-unit townhouse development on the subject lands. In November 2009 the OMB (PL081357) approved a modified plan, which consisted of a 15 Lot Single Family Development, located on a condominium roadway. On December 12, 2011 to address the Region of Halton issues related to removing the holding provision on the rezoning, Trafalgar Engineering Ltd. prepared an Updated Functional Servicing Report for the property. On June 11, 2012 Trafalgar Engineering Ltd. prepared a Stormwater Drainage Design Brief for the subject lands in support of the detailed engineering submission made to the Town of Oakville. Recently Fernbrook Homes (Bronte 15) Limited acquired the property immediately west of the subject lands at 3059 Lakeshore Road West, and plans to include these lands with the development of 3047 Lakeshore Road West. The resulting development will now have 18 single family lots located on a private condominium roadway. This report combines Trafalgar s December 12, 2011 Updated Functional Servicing Report and the June 11, 2012 Stormwater Drainage Design Brief, and updates these documents for the proposed 18 Lots. 1

3 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: Site Location and Description The subject lands are located at 3047 and 3059 Lakeshore Road West, on the north side of Lakeshore Road West, approximately 100m east of Mississaga Street. The site is bounded by the rear of the residential lots located on Mississaga Street on the west, Riverview Street on the north and Triller Place on the south. The single family house previously on the 3047 site was demolished in December, The development of these lands will include 18 single family residential lots with frontage onto a T-shaped private condominium road. The total site area is Ha. The site originally had a large valley running through the site from Mississaga Street to Lakeshore Road West. At Lakeshore Road West there is a 1200mm diameter pipe that receives drainage from the site and conveys it to the 1500mm diameter trunk sewer located along Lakeshore Road West. The upstream drainage has been cut off by a sewer along Mississaga Street, west of the site, and the 1200mm outlet only receives local drainage. 2.0 MUNICIPAL SERVICES (Water, Wastewater) 2.1 Water Supply and Distribution There currently exists a 150mm diameter watermain along the north side of Lakeshore Road West, immediately adjacent to the site. It is proposed that a 150mm diameter connection be made to the existing main. In accordance with the Region s requirements, the water system will be split at the property line, and a 150mm diameter Fireline and a 100mm diameter domestic service will be extended into the property adjacent to the roadway. Each unit within the development will be connected to the domestic main and each unit will be individually metered. 2

4 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: 1448 To provide fire protection, one internal hydrant will be provided. Based on a proposed development, the estimated maximum hourly demand for the development will be 0.55 l/s. 2.2 Wastewater There is a 375mm diameter wastewater main located on Lakeshore Road West, immediately adjacent to the site. The site will be connected to the existing main with a 200mm diameter connection. As part of the proposed storm drainage works the existing storm sewer at the front of the property will be lowered. This will allow the proposed sanitary lateral for the property to pass over the storm sewer and be directly connected to the existing sanitary main. The sewer at the property line will have an invert elevation of approximately 78.11m. The internal roadway and houses will be designed to insure that the future basements are serviced by gravity. The estimated peak flow from the proposed development is 0.88 l/s. The subject lands are tributary to the Marine Drive Wastewater Pumping Station. This station had been previously identified as not having sufficient capacity. The Region of Halton is currently undertaking improvements to the station, which are scheduled for completion in the fall of The station upgrade includes capacity for the original 15 lots of this development. In addition, the Region of Halton has added additional capacity to the station, which will be sufficient for the additional lots. 3

5 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: STORM DRAINAGE 3.1 Background In May, 2007, Planning & Engineering Initiatives Ltd. prepared a Stormwater Management Report in support of the development application at 3047 Lakeshore Road West, Oakville. In a letter dated October 8, 2009, the report was updated with a SWM Addendum (IBI Addendum) prepared by IBI Group and authored by Brian Enter, P. Eng. This report builds on the IBI Addendum and outlines the rationale for the design of the storm drainage system for the proposed development. 3.2 Proposed Drainage System To accommodate sanitary sewer requirements and to ensure that a positive down grade is provided for the development roadway, the condominium roadway has been designed at a 0.6% gradient running into the site from Lakeshore Road West. The front yards of the proposed lots will all drain towards the roadway and drainage will be collected by a series of roadway catchbasins. Under extreme rainfall conditions the major flows will be conveyed along the internal driveway to Lakeshore Road West. As a result of the existing topography and tree protection, the rear of the lots will be lower than the proposed internal roadway. A series of rear lot catchbasins have been proposed around the site to drain the rear yard and the adjacent surrounding lands. These rear lot catchbasins will be connected to the internal storm sewer system. There is a deep drainage swale located near the north-west corner of the site that collects a drainage area to the north-west. To collect drainage from this area, a 375mm diameter sewer inlet connected to the internal sewer is proposed. 4

6 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: 1448 At the rear of Lots 1 to 4 the existing boundary grade is very low compared to the proposed rear yard grades and the existing driveway on the adjacent property. We have had discussions with the adjacent property owner (3039 Lakeshore Road West) and we have received their permission to re-grade and raise the common grade along the property line. A swale will be installed in this area and will be connected to a catchbasin located near Lakeshore Road West and within an irregular part of the Town s right-of-way. A catchbasin will replace the existing drain in the area and will be connected to the existing 1500mm diameter storm sewer located along Lakeshore Road West. At the south-east corner of the site, at the rear of Lot 1, a rear lot catchbasin will be installed to collect the local drainage. It is impractical to connect this rear lot catchbasin to the internal sewer system and therefore this rear lot catchbasin will be connected directly to the existing 1500mm diameter sewer on Lakeshore Road West. In a similar fashion a rear lot catchbasin will be located in the south-west corner of Lot 18 and connected directly to the Lakeshore Road West sewer. 3.3 Design Criteria The IBI Addendum undertook an evaluation of the local storm sewer system and combined major and minor drainage systems to produce a hybrid of the two that would represent the response of the drainage system to a 100-year event. The Storm Sewer Design sheet based on this approach determined that the total peak 100-year flow to the sewer system downstream of the subject site (IBI MH 4 to IBI MH 5) is 2.819m 3 /s. This included the post-development flow from the subject site. The reported capacity of the downstream system is 4.530m 3 /s. In general accordance with the Town of Oakville drainage requirements, the sewer along the internal driveway will be designed to for the 5-year flow from the areas draining directly to the internal roadway. Overland flow will be conveyed along the roadway to Lakeshore Road West. 5

7 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: 1448 For the rear areas there is no opportunity to convey the major storm to the internal driveway. To address this issue, the internal storm sewer systems have been sized based on receiving the 100- year runoff for the rear yards and external drainage areas. The Town of Oakville staff have expressed concern with the drainage of the swale running from Mississaga Street to the proposed development. They requested the sewers within the development be sized assuming a runoff coefficient of C=0.70 from this area. (This runoff coefficient is normally used for higher density developments such as townhouses.) The incorporation of the higher runoff coefficient into the design of the sewer system does not imply that the Town will support redevelopment of these lands to this level. In addition, connecting to the site sewer or increasing the flows to this sewer will require the party connecting/increasing flows to obtain the Town of Oakville s approval to do so and to enter into an agreement with the condominium corporation to acquire the appropriate easement, to cover such items as long term maintenance and the cost of oversizing of the sewers. The attached Storm Sewer Design Sheet uses the standard Rational Method to calculate the drainage from the front lot areas and roadway. To account for the 100-year runoff from the rear areas, a peak flow has been calculated using the Rational Method with a fixed rainfall intensity of 200mm/hr. The 100-year runoff was added directly to the 5-year runoff from the front areas to get a Design Flow. 3.4 Lakeshore Road Sewer Replacement The original Planning & Engineering Initiatives Ltd. design assumed that the existing 1200mm diameter pipe, currently acting as an outlet from the site, would be utilized as an outlet for the site. In addition, they proposed that the sanitary sewer connection for the site would be located to the east of the storm sewer connection. To accommodate the storm and sanitary connections, a significant sideyard setback on Lot 1 was required to accommodate these sewers. 6

8 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: 1448 To better utilize the site, we are proposing a direct connection to storm and sanitary infrastructure on Lakeshore Road West. The existing 1200mm diameter sewer along Lakeshore Road West will be lowered to allow the site sanitary sewer to connect to the existing sanitary sewer on the south side of the roadway. The existing 1200mm diameter connection to the site will be removed and the site s storm sewer will be connected to the lowered sewer. The new 1200mm diameter sewer will be installed at 1.0% and will have a capacity of 4.078m 3 /s, well in excess of the m 3 /s peak sewer flow reported in the IBI Addendum. 3.5 Spill from Mississaga Street The IBI Addendum hydraulic grade calculations indicate that there is only 8cm freeboard at the Mississaga Street sag. They suggested this be increased to 30cm. We have reviewed detailed topographic information of this area and have concluded it is not possible to raise freeboard in this area without adversely impacting the adjacent driveway and properties, and as such, have not re-graded this area to provide additional freeboard. In the extremely rare event that there is a spill from Mississaga Street, there is added capacity in the downstream subject site system to handle additional flows. 7

9 Update Functional Servicing Report Trafalgar Engineering Ltd. 3059/3047 Lakeshore Road West, Oakville September 14, 2012 Project: 1448 Water Quality Enhanced water quality protection is required for the site. Based on the site drainage area, including the external area of 1.99ha. and an estimated impervious percent of 35%, a STC2000 Stormceptor Manhole is required to provide enhanced water quality control. 3.0 SUMMARY 1. An internal watermain will be constructed along the proposed roadways to provide domestic water and fire protection. The system will be connected to the existing watermain on Lakeshore Road West. 2. An internal sanitary sewer system will be constructed along the internal roadways and will be connected to the existing sanitary sewer along Lakeshore Road West. 3. The internal sewer system has been designed with a capacity for 100-year flows from the rear lots and external drainage and 5-year capacity for the internal roadway and private roadway. 4. An internal overland flow path has been provided along the private driveway to Lakeshore Road West. 5. The existing storm sewer on Lakeshore Road West will be lowered to improve sanitary and storm sewer servicing of the site. 6. The potential spill from Mississaga Street has been reviewed. It has been determined that raising the freeboard at Mississaga Street as suggested by IBI is not practical. 8

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11 APPENDIX A Calculations

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16 APPENDIX B IBI Addendum

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