STORMWATER MANAGEMENT REPORT DRAFT PLAN OF CITY OF GUELPH

Transcription

1 Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH PRELIMINARY NOVEMBER 2, 2011

2 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH DOCUMENT CONTROL Client: Debrob Investments Limited Project Name: Report Title: IBI Reference: Version: Draft Plan of Subdivision, Cityview Drive City of Guelph Stormwater Management Report Draft Plan of Subdivision, Cityview Drive City of Guelph Digital Master: [J:\Kitchener\25528_CityviewDr\5.0 Design (Work) Phase\Stormwater\Preliminary\WTRswmPRELIMINARY docx\ \AK] Originator: [AK] Reviewer: Authorization: Circulation List: History: November 2, 2011 Page 1.

3 I B I G R O U P P R E L I M I N A R Y TABLE OF CONTENTS 1. INTRODUCTION EXISTING CONDITIONS Hydrogeological Setting PROPOSED CONDITIONS STORMWATER MANAGEMENT East-Draining Area West-Draining Area Regulatory Floodline Water Balance Requirements Stormwater Quality Control EROSION AND SEDIMENT CONTROL CONCLUSIONS... 6 TABLES Table 1: Land Use Characteristics... 3 FIGURES Figure 1: Site Location... 1 Figure 2: Existing Drainage Areas... 2 Figure 3: Proposed Drainage Areas... 2 Figure 4: Grangehill Subdivision Catchment Areas... 3 Figure 5: Valleyhaven Subdivision Catchment Areas... 3 Figure 6: OGS Drainage Area... 4 APPENDICES Appendix A Background Information Appendix B Preliminary Water Balance Calculations November 2, 2011 Page i.

4 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH 1. INTRODUCTION IBI Group was retained to prepare a Preliminary Stormwater Management Report in support of a planning application prepared on behalf of Debrob Investments Limited for the creation of a Draft Plan of Subdivision in the City of Guelph. This application proposes the development of the existing vacant site for residential and commercial purposes. The subject lands are located on the east side of Cityview Drive within the City of Guelph, and comprise of two properties, 55 and 75 Cityview Drive. The lands are legally described as Part of Lots 25, 31, and 32, Registered Plan 53 and Part of Lot 4, Concession 3, Division C. Refer to Figure 1 for the development location. The total property area owned by the developer is ha. The purpose of this Report is to establish the preliminary design for stormwater management, and to satisfy the criteria of the agencies reviewing the Report. The proposed development is subject to the criteria set out by the City of Guelph, the Grand River Conservation Authority, and the Ontario Ministry of the Environment Stormwater Management Planning and Design Manual (MOE 2003). This Preliminary Stormwater Management Report is based on the information contained in the following documents: Grangehill Estates Stormwater Management Design Brief, Stanley Consulting Group Ltd., October 1998; Grangehill Subdivision Phase 3, External Storm Drainage Area Plan (As-recorded), Stantec Consulting Ltd., April 1999; Final Stormwater Management Design Report for the Southern Hadati Creek Watershed, Upstream of the C.N. Railway Tracks, City of Guelph, Schaeffers Consulting Engineers, May 1997; Stormwater Management Design Report Draft Plan 23T and 23T Martini/Valeriote Subdivision City of Guelph, Gamsby Mannerow Limited, March 19, 2004; Design Brief, Valleyhaven Subdivision Phase II City of Guelph Revised, Gamsby Mannerow Limited, May 2003; Ministry of Environment Stormwater Management Planning and Design Manual (MOE, 2003); Geotechnical Investigation, Chung & Vander Doelen Engineering Ltd. (July 27, 2006); and Hydrogeological Investigation, Cityview Drive Development, Guelph, Ontario, Anderson GeoLogic Limited, June EXISTING CONDITIONS The 55 Cityview Drive site is currently vacant and no buildings or structures exist on the property. A single detached dwelling and two out-buildings are located on the 75 Cityview Drive property. The lands to the north, east and west of the subject property consist of residential development. Lands to the south of the subject property are proposed for residential development. November 2, 2011

5 SUBJECT PROPERTY FIGURE 1 SITE LOCATION DEBROB INVESTMENTS LTD. - CITYVIEW DRIVE SCALE N/A DATE NOVEMBER, 2011 PROJECT No QUEEN STREET SOUTH KITCHENER, ONTARIO N2G 1W6 (519)

6 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH Based on the Geotechnical Investigation prepared by Chung & Vander Doelen Engineering Ltd., the site soil is generally sandy loam and silt till. The site has a drainage split, with ha draining to the east (area 101), and ha draining to the west (area 102). Existing drainage areas are shown on Figure 2. The topography is characterized by relatively gentle slopes on the western portion of the site with runoff draining overland in northeast to southwest direction toward Cityview Drive. Runoff enters a drainage ditch on the east side of Cityview Drive and then flows under the Railway line via a culvert draining to the south. The eastern portion of the site is characterized by relatively steep slopes, with drainage in a northwest to southeast direction. Runoff from the eastern portion of the site flows overland to a drainage swale along the eastern property boundary, which then flows south toward Clythe Creek. 2.1 Hydrogeological Setting Based on the Hydrogeological Assessment (Anderson GeoLogic Ltd. June 2011), the PSW located in the northwest end of the property is fed directly by surface water runoff (including interflow, which is the transient near-surface flow that originates from recent runoff events and which moves short lateral distances through surficial soil layers). There is no apparent upwelling or discharge of groundwater to the PSW, although shallow groundwater likely passes beneath the wetland. A detailed water balance assessment for the subject property has been completed in the Hydrogeological Assessment, based on the primary source of water to the PSW on the property being from surface water runoff and shallow interflow. The water balance has been used to develop targets for proposed conditions runoff. Given the relatively low permeability of the native surficial soils, active infiltration measures are not considered feasible for the development. 3. PROPOSED CONDITIONS Within the Draft Plan of Subdivision, it is proposed to protect the wetland and natural wooded areas and develop the agricultural areas. The proposed Draft Plan of Subdivision will create the proposed residential development together with the previously submitted Zoning By-law Amendment. The Draft Plan will consist of internal streets with access to Cityview Drive and Starwood Drive, and various accesses to surrounding residential development through Keating Street and Silurian Drive. The development will consist of single detached dwellings, semi-detached dwellings, on-street townhouses, multiple dwellings in the form of cluster townhouses and apartments, as well as future development blocks. The Draft Plan of Subdivision will also comprise of open space areas and parkland. The proposed Subdivision is shown on Figure 3, and land use characteristics are provided in Table 1. Stormwater management will be provided within offsite facilities as outlined in Section 4.0 below. A portion of the storm sewer will be routed through oil/grit separator units so that treated runoff to the wetland continues to provide surface water flow. The storm sewer for the site will be sized to account for external drainage areas. November 2, 2011 Page 2

7 LEGEND ha ha 6.438ha 379 QUEEN STREET SOUTH KITCHENER, ONTARIO N2G 1W6 (519) SCALE DATE PROJECT No. 1:3000 NOVEMBER, EXISTING DRAINAGE AREAS DEBROB INVESTMENTS LTD. CITYVIEW DRIVE FIGURE 2

8 STREET G STREET C LEGEND STREET E ha ha STREET F ha STREET D STREET B STREET A STREET A ha ha 379 QUEEN STREET SOUTH KITCHENER, ONTARIO N2G 1W6 (519) SCALE DATE PROJECT No. 1:3000 NOVEMBER, PROPOSED DRAINAGE AREAS DEBROB INVESTMENTS LTD. CITYVIEW DRIVE FIGURE 3

9 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH Table 1: Land Use Characteristics Lots/Blocks Proposed Land Use Area (ha) Units 1-49, Single Detached Dwellings , Semi-Detached Dwellings Street Townhouse Dwellings and 154 Cluster Townhouse Dwellings Apartment Dwellings Parkland 1.17 n/a 157 Open Space n/a Future Residential Development Road and Reserves n/a Total STORMWATER MANAGEMENT Existing stormwater management facilities have been constructed to the southeast and southwest of the proposed development. These facilities have been sized to provide both quantity and quality control of the stormwater runoff generated by the proposed development. A detailed review of the Reports and drawings listed in Section 1.0 was undertaken to demonstrate that sufficient capacity is available in the existing off-site facilities. Prior to development of the subject property a detailed Stormwater Management Report will be completed to the satisfaction of the City of Guelph and the Grand River Conservation Authority. 4.1 East-Draining Area Proposed conditions runoff from the ha east-draining portion of the development (area 201 on Figure 3) has been accounted for in the Stantec design for the Grangehill Estates development (refer to Figure 4). Stormwater will be conveyed to the existing stormwater management facility located on Watson Parkway via internal storm sewers sized to convey the minor storm runoff (5 year storm event). Major storm events will be conveyed overland to the pond within the road right-of-way. Drainage from the site will connect to the existing storm drainage system on Starwood Drive, and the storm sewer design for the subdivision will account for external drainage areas from existing development the north. 4.2 West-Draining Area Proposed conditions drainage from the 4.929ha west-draining portion of the development (areas 202 and 203 on Figure 3) has been accounted for in the Gamsby Mannerow design for the Valleyhaven Subdivision development (refer to Figure 5 and correspondence in Appendix A). Stormwater will be conveyed to the existing stormwater management facilities located within the Valleyhaven Subdivision north of the Railway line. Runoff will discharge via internal storm November 2, 2011 Page 3

10 LEGEND W AR ST SUBJECT PROPERTY D OO A IV DR T E E RE W AT SO N PK W Y ST NOTE: DRAINAGE AREAS SHOWN ARE FROM THE AS RECORDED STANTEC DRAWING R-104 DATED NOVEMBER 24, QUEEN STREET SOUTH KITCHENER, ONTARIO N2G 1W6 (519) SCALE N/A DATE NOVEMBER, 2011 PROJECT No GRANGEHILL SUBDIVISION CATCHMENT AREAS DEBROB INVESTMENTS LTD. CITYVIEW DRIVE FIGURE 4

11 LEGEND SUBJECT PROPERTY STREET A NOTE: DRAINAGE AREAS SHOWN ARE TAKEN FROM THE GAMSBY MANNEROW - MARTINI/VALERIOTE STORM WATER MANAGEMENT REPORT DATED OCTOBER 23, QUEEN STREET SOUTH KITCHENER, ONTARIO N2G 1W6 (519) SCALE DATE PROJECT No. N/A NOVEMBER, VALLEYHAVEN SUBDIVISION CATCHMENT AREAS DEBROB INVESTMENTS LTD. CITYVIEW DRIVE FIGURE 5

12 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH sewers sized to convey the minor storm runoff (5 year storm event). Major storm events will be conveyed overland to the pond within the road right-of-way. Runoff from rear lot catchment area 203 will discharge to Cityview Drive via the proposed development to the south. Runoff will be routed to an upgraded storm sewer and road system on Cityview Drive, and will then flow west adjacent to the railway line to the existing pond (refer to Figure 3). An easement (or block) will be secured to provide a suitably sized servicing corridor for storm, sanitary, and water services, and to provide an overland flow route for events up to the 100 year storm. The drainage system will be sized to account for flows from the proposed development to the south. 4.3 Regulatory Floodline GRCA mapping shows a drainage course tributary to Clythe Creek flowing through the southeast corner of the subject property with an associated Regulatory Floodline at this location. Based on information received from the GRCA, the Regulatory Floodline elevation for Clythe Creek applicable to the site can reasonably be reduced from m to m (see correspondence in Appendix A). The official floodline is based on what may be considered overly conservative flows from hydrology in the Eastview Secondary Master Drainage Report (1992). Based on discussions with John Palmer, Water Resources Engineer from the Grand River Conservation Authority, instead of a Regulatory flow of m 3 /s used in the Eastview Secondary Master Drainage Report, other reliable studies indicate that Regulatory flows in Clythe Creek at the railway underpass (just north of York Road) are less than 42 m 3 /s. Using a HEC-RAS model developed in support of the Watson Parkway realignment using this lower flow value, Mr. Palmer has estimated the backwater elevation upstream of the railway underpass will not be higher than m for the Regulatory storm event. Based on the topographic survey information, the lowest elevation on the subject lands is approximately m. Although we cannot as yet adopt this updated floodline elevation for Regulatory purposes, the GRCA have indicated that they can comfortably state that there is no floodplain within the proposed development if the existing grades on the property are higher than m. 4.4 Water Balance Requirements The strategy for stormwater management should include the following components, as recommended in the water balance analysis completed in the Hydrogeological Assessment: The runoff quantity to the wetland is calculated in accordance with the Table 1 wetland runoff targets in the Hydrogeological Assessment. Based on that Report, the total runoff and lateral inflow of shallow groundwater to the wetland is 16,900 m 3 /year; Since the wetland on site is sustained by surface water runoff and lateral inflow of shallow groundwater, these quantities should be maintained by diverting treated storm runoff as surface flow to three locations as shown on the preliminary engineering drawings; Referring to Figure 6, each of the three catchment areas (301, 302, and 303) will have ha of area treated and diverted to the wetland to match the existing runoff and lateral groundwater inflow value of 16,900 m 3 /year. Preliminary calculations are provided in Appendix B; November 2, 2011 Page 4

13 N :2000 (m) 246 BRANT AVENUE BRANTFORD, ONTARIO N3T 3J5 (519) SCALE DATE PROJECT No. FILE:T:\25528_CityviewDr\5.9 Drawings\59civil\layouts\25528PLT-STM.dwg LAYOUT:SWM FIG 6 LAST SAVED BY:Paul.rodrigues, Wednesday, November 02, :17:37 PM PLOTTED BY:Paul Rodrigues Wednes

14 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH The details of the outlet locations will be provided at the final design stage, and will include appropriate erosion protection measures since the design will include pipes with headwalls discharging to grade. 4.5 Stormwater Quality Control Although stormwater quality control is provided in the off-site pond facilities, the portions of the drainage areas diverted to the wetland must be treated. Stormwater quality control for the road drainage is therefore to be provided for an Enhanced Protection Level prior to water being discharged to the wetland (80 percent TSS removal for OGS units). The OGS units will be sized at the final design stage to provide an Enhanced Protection Level for long-term suspended sediment removal, based on contributing drainage area and peak flow rate. Figure 6 shows the preliminary drainage areas to each of the three outlet locations. The OGS units should be inspected and cleaned as per the manufacturer s specifications. Conventional stormwater quality control measures will not remove salt from runoff, it is therefore recommended that the use of salt be minimized to as great an extent as possible in compliance with any City of Guelph policies and regulations. 5. EROSION AND SEDIMENT CONTROL During area grading, erosion and sediment control measures will be implemented to ensure sediment does not escape the subdivision nor impact environmental lands to be protected. This would take the form of silt fences and sediment control ponds strategically positioned on the subdivision at low points receiving overland flows. An environmental monitoring program would be developed as part of the approval process to ensure the erosion and sediment control measures are installed, maintained and are functioning as intended. Based on the relatively steep slopes and sandy soils, the overall erosion potential for the site is considered to be high. Therefore, the erosion and sediment control plan recommends a range of erosion control measures. The preliminary erosion and sediment control measures identified for the subject lands include the following items: Silt fence is to be erected before any grading or stripping begins on the site to protect the creek and other adjacent areas from migration of sediment in overland flow; The provision of a mud mat at the entrance(s) to the site to minimize the amount of sediment transported off the site on construction vehicle tires; All runoff will be directed to temporary sediment control features (via swales if necessary) to ensure that no untreated runoff is discharged from the site; All disturbed areas will be stabilized as quickly as possible to minimize the opportunity for November 2, 2011 Page 5

15 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH erosion; All disturbed areas not scheduled for construction within 30 days must be stabilized immediately as per OPSS 572; and Temporary sedimentation ponds will be provided at various locations throughout the development, and all construction runoff will be routed to these facilities. Details for erosion and sedimentation control will be provided during the final engineering design (including an Erosion and Sediment Control Plan). 6. CONCLUSIONS This Preliminary Stormwater Management Report clearly outlines the proposed development will meet the criteria set out by the Review Agencies as follows: It has been confirmed that both water quantity and quality control will be provided in existing off-site SWM facilities for both the east and west draining portions of the proposed development; Runoff from the east-draining portion of the development will be routed to the existing storm sewer system on Starwood Drive; Runoff from the west-draining portion of the development will be routed to an upgraded storm drainage system on Cityview Drive, and then to the Valleyhaven Subdivision SWM pond through an easement (or block) adjacent to the Railway lands; Water balance calculations for existing and proposed conditions have been prepared for the wetland area; Treated road runoff will continue to provide surface water flow toward the wetland on the property; Based on preliminary information provided by the GRCA, the Clythe Creek floodline does not encroach onto the subject lands; Preliminary erosion and sediment control features have been identified and will be finalized at the detailed design stage; Based on these conclusions, we recommend that this Preliminary Stormwater Management Plan be accepted by all review agencies in support of the Draft Plan of Subdivision with appropriate conditions. November 2, 2011 Page 6

16 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH All of which is respectfully submitted. Yours truly IBI GROUP Andy Kroess, M.Eng., P.Eng. Senior Water Resources Engineer J:\Kitchener\25528_CityviewDr\5.0 Design (Work) Phase\Stormwater\Preliminary\WTRswmPRELIMINARY docx\ \AK November 2, 2011 Page 7

17 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH APPENDIX A BACKGROUND INFORMATION November 2, 2011

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23 I B I G R O U P P R E L I M I N A R Y Debrob Investments Limited STORMWATER MANAGEMENT REPORT DRAFT PLAN OF SUBDIVISION, CITYVIEW DRIVE CITY OF GUELPH APPENDIX B PRELIMINARY WATER BALANCE CALCULATIONS November 2, 2011

24 Cityview Drive Draft Plan of Subdivision, City of Guelph Preliminary Wetland Surface Flow Calculation Target Annual Surface Runoff Volume = m 3 (based on Hydrogeologial Assessment) Area 301 Drainage Area = m 2 Area 301 Diverted to Wetland = 8750 Annual Rainfall = 920 mm Annual Total Runoff Volume (Area 301) = 5635 m 3 (based on 70% of rainfall as minor runoff) Area 302 Drainage Area = m 2 Area 302 Diverted to Wetland = 8750 Annual Rainfall = 920 mm Annual Total Runoff Volume (Area 302) = 5635 m 3 (based on 70% of rainfall as minor runoff) Area 303 Drainage Area = m 2 Area 303 Diverted to Wetland = 8750 Annual Rainfall = 920 mm Annual Total Runoff Volume (Area 303) = 5635 m 3 (based on 70% of rainfall as minor runoff) * Total Peak Flow to Wetland = m 3 * based on pipe flow (5 year storm) from Roads. IBI Group 11/2/2011