Hamlet of Dunmore April 2016
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HAMLET OF DUNMORE │ APRIL 2016 MASTER STORMWATER MANAGEMENT PLAN PREPARED FOR | PREPARED BY | CYPRESS COUNTY WSP CANADA INC. 816 - 2nd Avenue Suite 110, 1222 Brier Park Road NW Dunmore, Alberta T1B 0K3 Medicine Hat, Alberta T1C 0B7 Master Stormwater Management Plan WSP File: 14125113-00 Executive Summary On behalf of Cypress County, WSP Canada Inc. (WSP) has prepared a Master Stormwater Management Plan for the Hamlet of Dunmore in Cypress County, Alberta. Modeling of the entire Dunmore Plan area has been performed and preliminary results indicate the following: 1. A release rate (unit area discharge) of 2.70 L/s/ha be adopted for design of any stormwater infrastructure in the Dunmore Plan area. 2. Proposed culverts to be installed/upgraded at locations where modeling has shown the culvert capacity to be insufficient to pass the design flows. 3. Drainage channel alignments and sections should be developed where necessary. Conveyance system continuity must be ensured. As the details of the proposed development are those presented in the Scheffer Andrew report, it is anticipated that, as more detailed data becomes available, the drainage conveyance system components will need to be designed as per design intent in each subcatchment. The completed modeling was based on judicious use of topography so that downstream drainage system elements will be at similar or lower elevations than any upstream components. 4. Certain locations within the plan area may already have dugouts which could be integrated into the stormwater design. These locations should be investigated to see the feasibility of using pre-existing dugouts. The figures in the report may be consulted (Appendix 11). 5. Areas with known ponding issues should be investigated and remedial measures considered. 6. The existing vacant land at the southwest intersection of 10th Street and 4th Avenue should be investigated for possible inclusion as a stormwater management facility. Due to the elevation difference in the area (should this area be designated as a stormwater facility) a i Master Stormwater Management Plan WSP File: 14125113-00 storm lift station will be necessary to convey runoff to the north ditch of 3rd Avenue, just south of Highway 1. 7. Residents of the Hamlet of Dunmore have expressed concerns for the ponding which occurs along 4th Avenue near 10th Street. Poor definition of roadside ditches is cited. 8. Public consultation may be beneficial in determining areas of concern ii Master Stormwater Management Plan WSP File: 14125113-00 TABLE OF CONTENTS EXECUTIVE SUMMARY……………………………………………………………………………………………..i 1.0 OPTIONS AND HYDROLOGIC ASSESSMENT ................................................................. 1 1. INTRODUCTION ................................................................................................................. 1 1.2 CYPRESS COUNTY DUNMORE MASTER AREA STRUCTURE PLAN ............................. 1 1.2.1 Vision, Objectives, and Stormwater Management ................................................. 1 1.2.2 The WSP option (Option C) .................................................................................. 2 1.2.3 Reasons for Preparing Option C ........................................................................... 2 1.2.4 No Interbasin Transfer .......................................................................................... 4 1.2.5 Topography, Gravel Extraction and Precipitation .................................................. 4 1.3 HYDROLOGICAL DATA AND HYDROMETRIC STATIONS ............................................... 7 1.4 FREQUENCY ANALYSIS.................................................................................................... 8 1.5 FREQUENCY DISTRIBUTION .......................................................................................... 10 1.6 SINGLE STATION FLOOD FREQUENCY ANALYSIS ...................................................... 12 1.6.1 Flood Data Source .............................................................................................. 12 1.6.2 Estimation of Missing Data.................................................................................. 13 1.6.3 Single Station Flood Frequency Analysis Results ............................................... 14 1.7 PRE AND POST DEVELOPMENT COMMENTARY .......................................................... 15 1.8 UNIT AREA RELEASE RATE (DISCHARGE) ................................................................... 15 2.0 SITE DESCRIPTION ......................................................................................................... 17 2.1 STUDY AREA ................................................................................................................... 17 2.2 REGIONAL DRAINAGE .................................................................................................... 17 2.3 LOCAL DRAINAGE BASINS ............................................................................................. 20 2.3.1 Drainage Basin A ................................................................................................ 20 2.3.2 Drainage Basin B ................................................................................................ 20 2.3.3 Drainage Basin C................................................................................................ 20 2.3.4 Drainage Basin D................................................................................................ 21 2.4 HAMLET DRAINAGE ........................................................................................................ 21 3.0 STORMWATER MANAGEMENT PLAN CONCEPTS....................................................... 24 3.1 GENERAL CONCEPTS..................................................................................................... 24 3.2 MAJOR-MINOR DRAINAGE SYSTEM .............................................................................. 26 3.3 SUBCATCHMENT DESCRIPTIONS ................................................................................. 27 3.3.1 Drainage Subcatchments .................................................................................... 27 3.3.2 Subcatchment Descriptions ................................................................................ 28 4.0 ANALYSIS METHODOLOGY ........................................................................................... 45 4.1 SINGLE EVENT ANALYSIS .............................................................................................. 45 4.2 COMPUTER MODELS ...................................................................................................... 49 5.0 POST DEVELOPMENT ANALYSIS .................................................................................. 51 TC-1 Master Stormwater Management Plan WSP File: 14125113-00 5.1 MODELLING PARAMETERS AND HYDROGRAPHS ....................................................... 51 5.1.1 Post Development Analysis and Modeling Parameters ....................................... 51 5.1.2 Hydrographs ....................................................................................................... 52 5.2 DETENTION PONDS AND DISCHARGE RATES ............................................................. 52 5.3 MODELLING LOGIC ......................................................................................................... 53 5.4 MODELLING RESULTS .................................................................................................... 53 6.0 CONCLUSIONS AND RECOMMENDATIONS ................................................................. 54 7.0 COST OF RECOMMENDATIONS .................................................................................... 58 8.0 IMPLEMENTATION .......................................................................................................... 59 9.0 REFERENCES .................................................................................................................. 61 10.0CORPORATE AUTHORIZATION ..................................................................................... 62 APPENDIX 1 – SWMHYMO (Computer) Modeling Results. APPENDIX 2 – Flood Frequency Analysis. APPENDIX 3 – Basin (Station) Transfer. APPENDIX 4 – Hydrometric Station Data Sheets from the Water Survey of Canada. APPENDIX 5 – Medicine Hat Airport IDF data sheets (Environment Canada 2014). APPENDIX 6 – A, B, C parameter development calculation. APPENDIX 7 – Subcatchment Data. APPENDIX 8 – Preliminary Pond Data Table. APPENDIX 9 – Preliminary Culvert Data Table. APPENDIX 10 – Alberta Environment Pond Approval for Eagle Ridge Pond. APPENDIX 11 – Figures 1 to 10. APPENDIX 12 – Rough Order of Magnitude (ROM) – Construction Cost Estimate TC-2 Master Stormwater Management Plan WSP File: 14125113-00 LIST OF FIGURES Figure 1.1 Bullshead Creek and Ross Creek Drainage basins (conceptual). Figure 1.2. Location of the hydrometric stations (Alberta Water Survey of Canada Active Stations). Figure 1.3 Hydrometric Station 05AH005 Seven Persons Creek at Medicine Hat. Figure 1.4 Summary of Common Frequency Distributions. Figure 1.5 Pearson III Distributions for Frequency Analysis. Figure 1.6. Linear Regression of I-MAX and MAX flow values. Figure 3.1. Drainage low point adjacent to proposed pond P-6 Figure 4.1 Chicago Design Storm (1:100 year, 24 hour duration) LIST OF TABLES Table 1. Results of Single Station Flood Frequency Analysis. Table 2. Unit area discharge from Single Station Flood Frequency Analysis. Table 3. Implementation Recommendations