Stormwater Management Report for the Macri Dixon Condo Block

Transcription

1 for the Macri Dixon Condo Block Town of Milton February 2017 JFSA Ref. No.: Prepared for : Prepared by : David Schaeffer Engineering Ltd.

2 52 Springbrook Drive, Ottawa, ON K2S 1B9 tel.: , fax: , in the Town of Milton February 2017 Prepared for : David Schaeffer Engineering Ltd. Prepared by : J.F. Sabourin, M.Eng., P.Eng. Laura Pipkins, P.Eng. Paul Wilson JFSA Ref. No.:

3 TABLE OF CONTENTS in the Town of Milton 1 INTRODUCTION AND OBJECTIVES DESIGN CRITERIA AND GUIDELINES Minor System Major System ASSUMPTIONS AND SOURCE OF DATA USED IN THIS STUDY PROPOSED MINOR AND MAJOR SYSTEM DRAINAGE Major System and DDSWMM Analysis Minor System and Hydraulic Gradeline Analysis EROSION AND SEDIMENT CONTROL DURING AND AFTER CONSTRUCTION SUMMARY, CONCLUSIONS AND RECOMMENDATIONS APPENDICES Appendix A: Appendix B: Appendix C: Appendix D: Rational Method Design Sheets (as per DSEL) DDSWMM Input and Output Files XPSWMM Model Schematic and Manhole Loss Coefficient Nomograph and Table Tables and Calculation Sheets Back Pocket: CD with DDSWMM and XPSWMM Modelling Files Page i

4 LIST OF TABLES Table 1: Comparison of Minor System Flows to the SWM Ponds... Page 9 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 4-Hour Chicago Storm (Free Outfall Conditions)... Page 11 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 4-Hour Chicago Storm (Restricted Outfall Conditions)... Page 16 LIST OF FIGURES Figure 1 : General Site Location... Page 3 Figure 2 : Proposed Minor System...(Back Pocket; Reduced Copy on Page 24) Figure 3 : Proposed Major System...(Back Pocket; Reduced Copy on Page 25) Figure 4 : Silt Control Measures during Construction (Silt fences)... Page 22 Figure 5 : Silt Control Measures during Construction (Catchbasin protection)... Page 22 Page ii

5 in the Town of Milton February INTRODUCTION AND OBJECTIVES (JFSA) were retained by David Schaeffer Engineering Ltd. (DSEL) to prepare a Stormwater Management (SWM) Plan for the Macri Dixon condo block, within the Mattamy Church Property. The Mattamy Church Property is tributary to SWM Ponds G and K, located within the Town of Milton. As shown by Figure 1, the development is on an angle relative to the compass, but will be described based on the nearest compass orientation for ease of reference. As shown by Figure 1, the proposed development is located west of Regional Road No. 25 and future development, east of Bronte Street, north of Britannia Road and future development, and south of Louis St. Laurent Avenue. Sixteen Mile Creek Tributary SWS-1-A passes through the site. The proposed Macri Dixon condo block is 1.63 ha, and was modelled at 99% imperviousness and fully tributary to SWM Pond G in the submitted June 2016 Design Brief for Stormwater Management Facility G for the Mattamy Church Property and December 2016 Stormwater Management Report for the Mattamy Church Property. The updated detailed design of the condo block proposes 1.43 ha at 82% imperviousness tributary to Pond G, with 0.20 ha of rearyard areas at 18% imperviousness draining directly to Tributary SWS-1-A. The February 2017 Addendum to Design Brief for Stormwater Management Facility G for the Macri Dixon Condo Block demonstrates that, with the latest design of the Macri Dixon condo block, Pond G will still operate in conformance with the requirements of the June 2016 Design Brief for Stormwater Management Facility G for the Mattamy Church Property. The Mattamy Church Property has a total drainage area of ha. Approximately 7.19 ha of the subdivision (in Phases 1 and 3) will drain uncontrolled to Tributary SWS-1-A, including 1.46 ha of residential rearyards, 0.20 ha of rearyards in the Macri Dixon condo block, and 5.52 ha of channel and buffer blocks. Similarly, a 0.01 ha buffer / road widening block (in Phase 2) will drain overland to Bronte Street. Another 8.17 ha of residential development (in Phase 3) of the subdivision drains to proposed SWM Pond K (designed by others). Finally, ha of the Mattamy Church Property (in Phases 1, 2 and 4) is tributary to SWM Pond G, including a 1.56 ha pond block (Pond G), a 2.75 ha school block, a 4.23 ha park block, 1.43 ha of the Macri Dixon condo block, and ha of residential development. The total drainage area to SWM Pond G is ha, including ha of the Mattamy Church Property (including the Macri Dixon condo block), a 1.21 ha external pond block (Pond G), a 7.33 ha external existing school block (Jean Vanier Catholic Secondary School), 2.18 ha of external Bronte Road, 1.02 ha of external future residential development, and 0.21 ha of Page 1

6 external existing residential development. Note that the external future residential development is located on Whitlock Avenue, Day Terrace, Leger Way, and south of Hatt Court. The external existing residential development is located north of Lemieux Court. Also note that only minor system flows will be conveyed to Pond G from 0.98 ha of the west side of external Bronte Road, with excess major system flows continuing south under interim conditions, and draining west to a future development under ultimate conditions. The total drainage area to SWM Pond K is ha, including 8.17 ha of the Mattamy Church Property, a 1.94 ha external pond block (Pond K), a 2.15 ha external school block (Boyne Public School), and ha of external future residential development. SWM Ponds G and K discharge to Sixteen Mile Creek Tributary SWS-1-A. The purpose of the present study/report is to evaluate the major and minor system flows of the proposed development to Ponds G and K, including the Macri Dixon condo block tributary to Pond G, with respect to the Town of Milton stormwater management guidelines and to check the adequacy of the proposed pipe sizes to convey the 5-year and the 100-year storm flows from within the development and from external areas. Background documents that were reviewed in preparing this report include the following: - Stormwater Management Planning and Design Manual, Ministry of the Environment, March Erosion and Sediment Control Guidelines for Urban Construction, Conservation Halton et al., December Town of Milton Engineering and Parks Standards, Town of Milton, August Boyne Survey Block 2 Final Subwatershed Impact Study, More Than Engineering, July [ ] RE: Bronte Street and Britannia Road Reconstruction Sizing for Facilities H and G, Boyne Survey Block 2 Area, AMEC Environmental and Infrastructure, November 5, Functional Stormwater and Environmental Management Strategy, Boyne Survey Secondary Plan Area, AMEC Environmental and Infrastructure, November Mattamy Church Property / Hydraulic Analysis of Tributary SWS-1-A, J.F. Sabourin and Associates Inc., March Gulfbeck Developments Subdivision - Stormwater Management Design Report SWM Pond K, The Municipal Infrastructure Group Limited, October Design Brief for Stormwater Management Facility G for the Mattamy Church Property, David Schaeffer Engineering Ltd. and, June for the Mattamy Church Property, J.F. Sabourin and Associates Inc., December The DDSWMM and XPSWMM programs were used to model the major and minor systems, to ensure that all of the Town of Milton s stormwater management requirements are satisfied. The general SWM design criteria and guidelines which are to be met are described in Section 2. Page 2

7 Figure 1: General Site Location Page 3

8 2 DESIGN CRITERIA AND GUIDELINES The design criteria and guidelines used for the stormwater management of the subject subdivision are those that were developed in the background documents as well as those provided in the August 2014 Town of Milton Engineering and Parks Standards and generally accepted stormwater management design guidelines. During the course of the detailed design, it was determined that the 1.63 ha Macri Dixon condo block has an average imperviousness of 74%. The ha Church Property (including the Macri Dixon condo block) has an average imperviousness of 49%. Including external areas, the ha drainage area to SWM Pond G has an average imperviousness of 59%. Including external areas, the ha drainage area to SWM Pond K has an average imperviousness of 62%. Average imperviousness values are calculated based on a weighted average of the relevant subcatchment areas, as presented in Figure 3. A detailed analysis of the proposed dual drainage system was required to confirm that the following general design criteria and guidelines for the minor and major systems would be met. 2.1 Minor System a) Storm sewers on local roads are to be designed to provide a 5-year level of service. b) Sump pumps will be provided within residential units where the storm sewer is not sufficiently deep or where the storm sewer will be subject to elevated water levels during infrequent storms. Sump pumps are to be installed in accordance with Section of the August 2014 Town of Milton Engineering and Parks Standards. c) Inlet control devices shall not be installed. d) Grates for road catchbasins are to be flush type OPSD , and grates for catchbasins in rear yards, park and open spaces with pedestrian traffic are to be flush type OPSD e) Single catchbasins are to be equipped with 250 mm minimum lead pipes and double catchbasins are to be equipped with 300 mm minimum lead pipes. f) Under full flow conditions, the allowable velocity in storm sewers is to be no less than 0.75 m/s and no greater than 6.0 m/s. Page 4

9 2.2 Major System a) The major system shall be designed with sufficient capacity to allow the excess runoff of a 100-year storm to be conveyed within municipal property. b) Roof leaders shall be installed to direct the runoff to splash pads and on to grassed areas. c) Flow across road intersections shall not be permitted for minor storms (generally 5-year or less). d) For the 100-year storm and for all roads, the depth of water at the crown shall not exceed 0.15 m. The maximum depth of water on streets, rearyards, public space and parking areas shall not exceed 0.30 m. e) A minimum of 0.30 m freeboard is to be provided to building openings. When catchbasins are installed in rear yards, safe overland flow routes are to be provided to allow the release of excess flows from such areas. f) The product of the maximum flow depths on streets and maximum flow velocity must be less than 0.65 m 2 /s on all roads. Page 5

10 3 ASSUMPTIONS AND SOURCE OF DATA USED IN THIS STUDY Sources of information and assumptions made in this study are listed below: - Stormwater management model: DDSWMM (release 2.1) and XPSWMM (version 2014) - Minor system design: 1:5 year (see rational method in Appendix A) - Major system design: 1:100 year - Max. flow depth on roads: 0.3 m above gutter; 0.15 m above crown - DDSWMM model parameters: Fo = 76.2 mm/hr, Fc = 13.2 mm/hr, DCAY = 4.14/hr, D.Stor.Imp. = 0.80 mm, D.Stor.Per. = 1.50 mm Detailed Area Imperviousness: based on development layout and taken as fully effective in the front lot portion and half effective in rear lot portion of each house. Lumped Area Imperviousness: based on runoff coefficient (C) where C = 0.7 x imperviousness ratio Design storms: 4-hour Chicago as per Town of Milton s criteria; peak averaged over 10 minutes. - Street catchbasin covers: OPSD Rearyard catchbasin covers: OPSD (100% capture) - Curb and gutter: OPSD on Gore Court, OPSD elsewhere. In the absence of flow capture curves for OPSD and curb and gutters, OPSD curb and gutters are assumed. - Manning's' roughness coeff.: for concrete and PVC pipes (free flow). - Minor system losses: Refer to Appendix C for manhole loss coefficients. - Extent of major system: Must be contained within the municipal right-of-way. - Depth of backyard swales: As per DSEL s Grading Plan - Street and pipe dimensions: As per DSEL s Plan and Profiles - Right-of-way characteristics: As per DSEL s Details of Roads - Downstream channel HGL: m based on the 100-year water level in Channel SWS-1-A at HEC-RAS cross-section 580 for Pond G, and m based on the 100-year water level in Channel SWS-1-A at HEC-RAS cross-section for Pond K, as per the March 2016 Mattamy Church Property / Hydraulic Analysis of Tributary SWS-1-A memo. Page 6

11 4 PROPOSED MINOR AND MAJOR SYSTEM DRAINAGE The proposed minor and major system drainage routes are shown in plan view in Figures 2 and 3, respectively. In accordance with the Town of Milton standards, the minor system has been designed to accommodate the 5-year post development flows from within the site and from external areas. A Rational Method design was conducted by DSEL (refer to Appendix A) in order to estimate minor system flows based on the Town of Milton IDF relationship and selected runoff coefficients. Note that the minor system capture on the following areas in the Church Property should be limited to the 5-year Rational Method flows (estimated below): External Existing Secondary School Block (A003SC1, ha, C = 0.65) : Elementary School Block 334 (A023SC1, ha, C = 0.75) : Neighbourhood Park Block 335 (A049PK1, ha, C = 0.40) : Neighbourhood Park Block 335 (A053PK1, ha, C = 0.40) : Neighbourhood Park Block 335 (A300PK1, ha, C = 0.35) : Neighbourhood Park Block 335 (A300PK2, ha, C = 0.36) : Neighbourhood Park Block 335 (A301PK1, ha, C = 0.38) : Neighbourhood Park Block 335 (A302PK1, ha, C = 0.39) : Neighbourhood Park Block 335 (A303PK1, ha, C = 0.39) : Neighbourhood Park Block 335 (A304PK1, ha, C = 0.40) : Neighbourhood Park Block 335 (Total) : External School Block (A103SC1, ha, C = 0.67) : 1382 L/s 603 L/s 59 L/s 369 L/s 5 L/s 8 L/s 11 L/s 22 L/s 28 L/s 35 L/s 537 L/s 421 L/s Excess flows from the areas above spill onto the street and are conveyed overland to the SWM ponds. For modelling purposes, minor system capture rates on undetailed existing and future external residential areas in the Mattamy Church Property were also limited to the 5-year Rational Method flows. Minor system capture rates on external Bronte Road were limited to the 5-year flow + 12%, as simulated using DDSWMM. The additional 12% capture is to account for the additional flows conveyed by surcharged pipes during the 100-year storm; that is, a greater head acting on the catchbasins, lead pipes and main storm sewer pipes during the 100- year storm results in greater capture than during smaller storm events. Page 7

12 Note that only minor system flows will be conveyed to Pond G from the west side of Bronte Road, with excess major system flows draining to an external system. The surface runoff collected by rearyard catchbasins is not to be controlled; hence they capture 100% of the 100-year flow. There are eighty-nine (89) such catchbasins within the Mattamy Church Property, two (2) of which are within the Macri Dixon condo block. Refer to Figure 2 for catchbasin locations. The street segments within the proposed development have been designed using a 'saw tooth' or 'sagged' road profile. The runoff from within these segments will be conveyed to catchbasins located at the lowest point within the street segment. Flows in excess of the catchbasin capture rate will be temporarily stored within the 'sagged' street segments and released slowly to the storm sewers. When the storage on a specific street segment is surpassed, the excess water will flow towards the next downstream street sag, and eventually to the appropriate outlet. It should be noted that the major system would outlet without flooding any of the properties within the subdivision. A 3.0 m wide overland flow route from Chretien Street to Neighbourhood Park Block 335, with a curb cut of 6.0 m, is provided west of the park. A 4.0 m wide overland flow route from Day Terrace to Pond G, with a curb cut of 10.0 m, is provided west of the pond. Refer to Calculation Sheet 2 of Appendix D for the capacity of the overland flow routes. Overland flow routes to Pond K are external to the proposed development, and are to be designed by others. The DDSWMM and XPSWMM analyses, discussed in the next sections, have demonstrated that the proposed drainage system for the subdivision will have sufficient capacity to control the excess flow during a 100-year event and safely capture and convey the 5-year flow to the ponds. 4.1 Major System and DDSWMM Analysis The DDSWMM computer program was used to model the major and minor system flows within the proposed development. The DDSWMM model presented in Appendix B was developed based on the information provided in Figures 2 and 3. Two simulations were conducted, one for each of the following rainfall events: i) A simulation of the 5-year, 4-hour Chicago storm; and ii) A simulation of the 100-year, 4-hour Chicago storm. The models use actual catchbasin capture flow curves, and the inflows are limited by lead pipe capacities. Note that 250 mm diameter lead pipes were assumed and are required between single catchbasins and the storm sewers, and 300 mm diameter lead pipes were assumed and are required between double or rearyard catchbasins and the storm sewers. Page 8

13 100-year intakes are located at the east end of Hinton Terrace near Lot 68 in order to prevent overland flow from draining overland to the adjacent channel block. For the 100-year storm, simulation results show that 185 L/s and 182 L/s are directed towards the catchbasins at the 100-year intake points on Hinton Terrace (on subcatchments A061NE and A061NW). Based on the assumed catchbasin grate capture curves and the capacity of lead pipes (refer to Calculation Sheet 3 of Appendix D), it was determined that two (2) OPSD double catchbasin grates on the east side of the road equipped with one (1) shared 300 mm diameter lead pipe, and two (2) OPSD double catchbasin grates on the west side of the road equipped with one (1) shared 300 mm diameter lead pipe, would have enough capacity to capture the incoming flow, even if the grates were 50% blocked. 4.2 Minor System and Hydraulic Gradeline Analysis The minor system analysis was completed using the XPSWMM program based on the peak flows captured during the 5- and 100-year Chicago storms as calculated with the DDSWMM program. Since several pipes will potentially surcharge to ground level during a 100-year storm, the XPSWMM model was extended on the surface to allow for the excess flow that cannot enter the minor system to be routed through the major system. These excess flows were reinserted into DDSWMM in the next downstream segment as hydrographs. The minor system was analyzed for both free outfall and restrictive downstream conditions. Restrictive downstream conditions for all storms were based on the 100-year water level of m in Channel SWS-1-A at the Pond G outfall (HEC-RAS cross-section 580), and m in Channel SWS-1-A at the Pond K outfall (HEC-RAS cross-section ), as per the March 2016 Mattamy Church Property / Hydraulic Analysis of Tributary SWS-1-A memo. Pond G was modelled as designed in the June 2016 Design Brief for Stormwater Management Pond G for the Mattamy Church Property by DSEL and JFSA, updated to reflect as-built conditions. Pond K was modelled as per the October 2016 Gulfbeck Developments Subdivision Stormwater Management Design Report SWM Pond K by The Municipal Infrastructure Group Limited. Table 1 presents the peak minor system inflows to the SWM ponds obtained with the Rational Method and with the above mentioned simulations. Table 1: Comparison of Minor System Flows to the SWM Ponds Location 5-Year Rational 5-Year DDSWMM/ 100-Year DDSWMM/ Method Flow XPSWMM Flow XPSWMM Flow (m 3 /s) (m 3 /s) (m 3 /s) MH 71 to Pond G MH 127 to Pond K Page 9

14 Table 1 shows that the 5-year total flow simulated with the DDSWMM/XPSWMM models is slightly higher than the Rational Method flow. This may be partly explained by the difference in the selected time of concentration and the fact that the Rational Method tends to underestimate design peak flows for areas larger than 10 ha. The DDSWMM/XPSWMM simulations have determined that for the selected 5- and 100-year storms, the total minor system peak inflows to Pond G would be m³/s and m³/s, respectively. For the selected 5- and 100-year storms, the total minor system peak inflows to Pond K would be m³/s and m³/s, respectively. The 100-year flow will surcharge most parts of the minor system; however for this analysis this is not critical as residential units with basements will be protected by sump pumps. In order to determine the extent of pipe surcharge, the 100-year water levels generated by the combined DDSWMM/XPSWMM models were compared against ground elevation, represented by the manhole cover elevation. When the computed HGL reached the manhole cover elevations in the XPSWMM, the excess flow was routed in a downstream DDSWMM segment to re-enter the minor system in a downstream pipe. This situation occurred at forty-four (44) locations within the proposed storm sewer network during the 100-year storm, one (1) of which is within the Macri Dixon condo block. Refer to Tables 2A and 2B below for spill locations and peak flows; all spill nodes in the XPSWMM model are prefixed with an S. Note that manholes within the Macri Dixon condo block are prefixed with M ( SM for spills). Within the proposed Church Property, including the Macri Dixon condo block, the depth of water on the road will be retained within the right-of-way and will not exceed the maximum allowable value of 30 cm at the gutter or 15 cm at the crown during the 100-year Chicago Storm (refer to Calculation Sheet 1 of Appendix D, where the calculated maximum was 14.5 cm at the gutter and 4.4 cm at the crown). Furthermore, it was determined that, for the 100-year event and for all major system segments, the product of the depth of water (m) at the gutter multiplied by the velocity of flow (m/s) will not exceed the maximum allowable 0.65 m 2 /s (refer to Calculation Sheet 1 of Appendix D, where the calculated maximum was m 2 /s). Tables 2A and 2B summarize the pipe data and hydraulic simulation results for the 100-year storm under free and restricted outfall conditions, respectively. Note that the flowing full pipe velocities are not less than 0.75 m/s and no greater than 6.0 m/s for all proposed pipes. Page 10

15 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Free Outfall Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A N/A N/A S4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S5 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S7 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S9 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S10 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S11 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S22 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S27 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S32 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S34 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S35 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

16 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Free Outfall Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A S37 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S39 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S42 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S43 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S45 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S46 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S60 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

17 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Free Outfall Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) PondG N/A S101 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S103 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S104 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S105 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S107 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S110 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S112 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S113 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S115 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S116 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S117 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S118 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S119 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S120 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

18 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Free Outfall Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A PondK N/A S144 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S340 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S400 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S401 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S402 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S403 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S404 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S405 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S406 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S407 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PondG Gout N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PondK Kout N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S3401 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S3402 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S92 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S93 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

19 Table 2A: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Free Outfall Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A N/A N/A S304 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M N/A M101 M N/A M102 M N/A M102 SM102 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M103 M N/A M103 SM103 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M104 M N/A M104 SM104 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A MB104 M N/A Note: (1) A negative surcharge implies that the pipe is not flowing full

20 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Restrictive Downstream Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A N/A N/A S4 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S5 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S7 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S9 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S10 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S11 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S22 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S27 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S32 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S34 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S35 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

21 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Restrictive Downstream Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A S37 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S39 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S42 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S43 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S45 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S46 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S60 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

22 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Restrictive Downstream Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) PondG N/A S101 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S103 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S104 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S105 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S107 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S110 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S112 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S113 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S115 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S116 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S117 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S118 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S119 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S120 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

23 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Restrictive Downstream Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A PondK N/A S144 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S340 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S400 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S401 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S402 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S403 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S404 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S405 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S406 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S407 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PondG Gout N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A PondK Kout N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S3401 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S3402 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S92 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A S93 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A

24 Table 2B: Pipe Data and Hydraulic Simulation Results for the 100-Year, 24-Hour Chicago Storm (Restrictive Downstream Conditions) U/S D/S U/S D/S Pipe Dia. Pipe Pipe Pipe n U/S MH D/S MH Design Design Peak Peak / Surcharge Time Max. Max. Freeboard MH MH Invert Invert / Height Width Length Slope Cover Cover Vel. Flow Pipe Design U/S to U/S D/S U/S HGL and Elev. Elev. Flow Flow (1) Peak HGL HGL MH Cover (m) (m) (mm) (mm) (m) (%) (m) (m) (m/s) (m 3 /s) (m 3 /s) (m) (h) (m) (m) (m) N/A N/A N/A N/A S304 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M N/A M101 M N/A M102 M N/A M102 SM102 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M103 M N/A M103 SM103 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A M104 M N/A M104 SM104 N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A N/A MB104 M N/A Note: (1) A negative surcharge implies that the pipe is not flowing full

25 5 EROSION AND SEDIMENT CONTROL DURING AND AFTER CONSTRUCTION Silt and erosion control strategies shall be implemented during construction activities in order to minimize the transfer of silt off site. The following measures should be implemented: i) Silt control fences shall be installed as required in order to prevent the movement of silt off-site during rainfall events. ii) Construction of a mud mat shall be installed at the site entrance in order to promote selfcleaning of truck tires when leaving the site. iii) All catchbasins shall be equipped with a crushed stone filter in order to prevent the capture of silt in the storm sewer system. iv) Regular cleaning of the adjacent roads shall be undertaken during the construction activities. v) Regular inspection and maintenance of the silt control measures shall be undertaken until the site has been stabilized. vi) The erosion and sediment control devices shall be removed after the site has been stabilized. vii) Refer to Site Alteration Permits , and associated with this development. Page 21

26 Figure 4: Typical installation of silt fences Figure 5: Catchbasin with geotextile to protect storm sewer pipes from sediment contamination Page 22