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Hydraulic Manual (Dec 2014)

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Hydraulic Manual (Dec 2014)

  1. 1. Hydraulic Manual 2013 2014
  2. 2. HM 001-00 Hydraulic Manual Section: CHANGE HISTORY Subject: Date Page September 18, 2014 1 of 2 September 15, 2014 Revised HM 614-00 and HM 000-00 Updated the culvert material types to include polypropylene and steel reinforced high density polyethylene on a pilot project basis. Updated the steel culvert material coating types to include polymer on a pilot project basis subject to additional manufacturing inspection requirements. The culvert connector requirements have been updated to replace the gasket requirement with a requirement to wrap the coupler with a non-woven geo-textile. Added a requirement for the use of a semi-corrugated coupler with electrometric O-Ring Gaskets to improve resistance to piping failures in fills greater than 3 m or water infiltration or continuous low flow conditions. Use of longer culvert lengths is now required in fills greater than 3 m to reduce the number of joint connections. Updated the name for the section. Updated the Table of Contents to reflect the slight change to the name of section 614-00 and the addition of section 001-00 Change History and the re-numbering of section HM 000-00 Table of Contents. September 18, 2014 Revised HM 701-00, HM 702-01, HM 702-02 and HM 704-00. Replaced Standard Plan HM705-01 with new Standard Plans HM705-01, and HM705-02. Revised Standard Plan HM705-02 and renamed it HM705- 03. Created new Standard Plan HM705-04. In HM 701-00 adopted the Canadian Highway Bridge Design Code (CHBDC) for the structural design of corrugated steel culverts equal to or greater than 3000 mm in diameter. The granular backfill specifications for road embankment CSP culverts have been revised to adopt a rectangular shape around the culvert with the dimensions based on CHBDC for 1500 mm ≤ D < 3000 and based on American Iron and Steel Institute (AISI) for D < 1500 mm. The guidance for spacing between multiple pipe installations has been amended to improve design flexibility. The guidance for design of camber has been amended to provide more specific guidance on its application. Standard Plan HM705-01 was replaced by the two new Standard Plans in order to implement the new granular backfill specifications based on culvert size. In Standard Plan HM705-02 Note 4 was removed so it can be used in multiple pipe installations. For Standard Plan HM705-04 the
  3. 3. Hydraulic Manual HM 001-00 Section: CHANGE HISTORY Subject: Date Introduction Page September 18, 2014 2 of 2 requirements are the same as before except that a separate plan has been included and the excavated slope has been amended to recognize the requirements of an unpaved approach versus a road embankment.
  4. 4. HM 002-00 Hydraulic Manual Section: TABLE OF CONTENTS Subject: Date Page September 18, 2014 1 of 4 000-00 Table Of Contents 001-00 Change History 002-00 Table of Contents 100-00 Introduction 101-00 Introduction 200-00 General Information 201-00 Use of this Manual 202-00 Use of Other Publications 203-00 Use of Professional Judgement 204-00 Design Exceptions 205-00 Use of the Terms Shall/Should/May 206-00 Roles and Responsibilities 206-01 Introduction 206-02 Technical Standards Branch 206-03 Regional Services Division 207-00 Definitions 300-00 Design And Approval Processes 301-00 Design Process 302-00 Design and Approval Requirements 303-00 Documentation Requirements 303-01 Hydraulic Design Reports 303-02 Hydraulic Approval Memo 304-00 Documentation Templates (Under Development) 305-00 Design Drawing Templates (Under Development) 400-00 Background Data Collection 401-00 Background Data Collection 500-00 Design Flows 501-00 Design Flow Methodology 502-00 Design Frequency
  5. 5. Hydraulic Manual HM 002-00 Section: TABLE OF CONTENTS Subject: Date Page September 18, 2014 2 of 4 503-00 Flow Calculation 503-01 Existing Structures at Site 503-02 Structures Upstream and Downstream 503-03 Rational Method 503-04 Transposition of Flows 504-00 Flow Frequency 505-00 Flow Conversion 600-00 Culvert Hydraulics 601-00 Introduction 602-00 Design Considerations 603-00 Inlet Control 604-00 Outlet Control 605-00 Allowable Headwater 606-00 Culvert Lengths And Minimum Diameters 607-00 Tailwater 608-00 End Treatments 609-00 Manning’s n 609-01 Pipe Flow 609-02 Constructed Channels 609-03 Natural Channels 609-04 Composite Manning’s n 610-00 Culvert Embedment 611-00 Wood Box Culverts 611-01 Design and Maintenance Considerations 611-02 Design Calculations 611-03 Standard Plans 12500: Framed Timber Culverts Page 1 of 5: Structural Details Page 2 of 5: Structural Details Page 3 of 5: Miscellaneous Details Page 4 of 5: Timber List Page 5 of 5: Timber List SP 22160: Backfilling Framed Timber Culverts 612-00 Median Drainage Structures
  6. 6. Hydraulic Manual HM 002-00 Section: TABLE OF CONTENTS Subject: Date Page September 18, 2014 3 of 4 613-00 Flow Over Embankments 614-00 Culvert Material and Connector Requirements 615-00 References 700-00 Structural Design 701-00 Structural Design Requirements 702-00 Height of Fill Tables 702-01 Corrugated Steel Pipe and Pipe Arch With D < 1500 mm 702-02 Corrugated Steel Pipe and Pipe Arch For 1500 ≤ D < 3000 702-03 Structural Plate Pipe 703-00 Structural Design Procedure 704-00 References 705-00 Standard Plans HM705-01: Backfilling Pipe Culverts D < 1500 mm In Road Embankment HM705-02: Backfilling Pipe Culverts 1500 mm ≤ D < 3000 mm In Road Embankment HM705-03: Backfilling Pipe Culvert D ≤ 600 mm In Unpaved Approach HM705-04: Backfilling Pipe Culverts 600 mm < D < 3000 mm In Unpaved Approach 800-00 Erosion Control At Culverts 801-00 Introduction 802-00 Design Principles 803-00 Design Requirements 804-00 Riprap Design 804-01 Sizing of Stone For Riprap 804-02 Riprap Apron 805-00 Natural Erosion Resistance 806-00 References 807-00 Standard Plans HM807-01: Riprap Pipe Culverts 600 mm < D < 1500 mm 900-00 Fish Passage Design Procedures 901-00 Fish Passage Design Procedures
  7. 7. Hydraulic Manual HM 002-00 Section: TABLE OF CONTENTS Subject: Date Page September 18, 2014 4 of 4 1000-00 Design Aids 1001-00 Design Aid Criteria 1002-00 CulvertMaster 1002-01 Operation 1002-02 Tutorial 1002-03 Design Examples 1100-00 Culvert Service Life (Under Development) 1200-00 Culvert Rehabilitation 1201-00 Introduction 1202-00 Culvert Sleeving 1203-00 References 2000-00 Technical Bulletins 2001-00 Design Directives
  8. 8. Hydraulic Manual Section 100 Introduction 2014
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  10. 10. HM 101-00 Hydraulic Manual Section: INTRODUCTION Subject: SCOPE OF MANUAL The Hydraulic Manual (HM) has been compiled as a reference document for the hydraulic design of culverts. In meeting that requirement, it also contains guidance applicable to the hydraulic design of bridges and open channels. The objective of culvert design is to select the most economical culvert to pass flow from a drainage area through the highway in a permissible manner with an acceptable risk of overtopping or damage from higher flows. The purpose of the Hydraulic Manual is to provide the designer with procedures for designing culverts while promoting uniformity of design on Saskatchewan Highways and supporting the provision of safe and efficient roads for the travelling public. Drainage is a major component of highway design. A poor culvert design may at best result in minor delays by overtopping the grade every year, and in extreme cases it may result in death and considerable property damage. It is hoped that with the aid of this guide, the designer is capable of handling culvert design problems to a degree of accuracy consistent with the accuracy of the field information. LAYOUT The guide’s layout is reflective of the natural grouping of the design topics that the designer will go through in order to undertake a culvert design. To assist designers, it includes section HM 1000-00 which includes, among other things, a series of design examples. DESIGN ASPECTS There are a number of aspects that shall be considered in a culvert design. These are: • Legal Aspects, • Hydrology, • Hydraulic Design, • Economics, • Navigation Concerns, • Environmental Concerns; and • Safety. LEGAL ASPECTS In the design of a hydraulic structure, the engineer shall ensure that it is Date Page January 31, 2014 1 of 2
  11. 11. Hydraulic Manual HM 101-00 Section: INTRODUCTION Subject: done according to accepted practices and that it meets applicable Federal and Provincial Acts and Regulations. Deviations that could result in damage and litigation should be avoided. HYDROLOGY Hydrology is concerned with the estimation of design discharges. Design discharge is often the overriding design criteria because all other aspects of the design are related to the design flow. Unfortunately, it may also be one of the most difficult aspects to determine. HYDRAULIC DESIGN Hydraulic design consists of looking at the different types of structures available to accommodate the design flows. It also incorporates all other drainage aspects into the design. It is therefore the next most important item in the design after the design flow estimate. ECONOMICS Most individual drainage structures on a highway system do not represent a large part of the total investment of highway funds. However, taken collectively, they represent a large investment. The usual procedure in hydraulic design is to consider a number of alternatives and to select one on the basis of economics. The most economic design is generally one where the costs of possible flooding and the material type are balanced against the cost of increased structure size and design life. NAVIGATION CONCERNS It is important that hydraulic structures do not restrict navigable waterways and meet the requirements of the Navigation Protection Act. ENVIRONMENTAL CONCERNS Any changes to existing drainage patterns may have an adverse effect on aquatic life and other flora and fauna. The requirements of regulatory agencies shall be taken into account during the assessment of possible effects. Changing the drainage pattern may also have a detrimental effect on the existing usage of adjacent land. Any changes to the existing drainage pattern and its effects on adjacent land shall be considered in the design. SAFETY The provision of a drainage facility should combine safety and efficiency in design. Drainage facility design should give serious consideration to the possibility of reducing or eliminating any feature that may pose a potential hazard to errant vehicles. Date Introduction Page January 31, 2014 2 of 2
  12. 12. Hydraulic Manual Section 200 General Information 2014
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  14. 14. HM 201-00 Hydraulic Manual Section: USE OF THIS MANUAL Subject: DISTRIBUTION This guide will not be issued or maintained in printed form. The manual is available through the Ministry of Highways and Infrastructure website. Users are encouraged to bookmark and use the manual from the website. If the user elects to download the guide, they shall then be responsible for checking the website to ensure that they always have the latest version prior to starting on any design work. USE WITHIN THE MINISTRY The Hydraulic Manual is to be used in conjunction with other Ministry publications; The U.S. Federal Highway Administration Hydraulic Design Series Number 5 – Hydraulic Design of Culverts and Hydraulic Engineering (HDS-5); and Circular No. 14 – Hydraulic Design of Energy Dissipators for Culverts and Channels (HDS – 14) in the design, tender, construction, rehabilitation, and decommissioning of culverts. Other Ministry publications are cross-referenced in this manual as required. The following is the ministry policy for the use of these publications: - If a design topic is addressed in both the Hydraulic Manual and HDS-5 or HDS-14, the Ministry standard procedure shall be to apply the information in the Hydraulic Manual as the Ministry Standard. - If a design topic is not addressed in the Hydraulic Manual or the HDS-5 or HDS-14, but is addressed in another publication, refer to HM 202-00. USE OUTSIDE THE MINISTRY The Ministry of Highways and Infrastructure recognizes that others may use the Hydraulic Manual. The Hydraulic Manual is a consideration of Ministry policies, standards, and practices. Therefore, it is not suitable for adoption by others as a design code or a set of minimum specifications, which if met will adequately protect the public. Hydraulic Manual users shall accept responsibility for each design produced and all associated risk of liability. Date General Information Page January 31, 2014 1 of 2
  15. 15. Hydraulic Manual HM 201-00 Section: USE OF THIS MANUAL Subject: THIS PAGE INTENTIONALLY LEFT BLANK Date General Information Page January 31, 2014 2 of 2
  16. 16. HM 202-00 Hydraulic Manual Section: USE OF OTHER PUBLICATIONS Subject: INTRODUCTION Designers may wish to consider information in publications other than the Hydraulic Manual. For example, designers must also consult other relevant ministry publications. Designers may also consult other sources for design guidance. This is especially beneficial when a particular design topic is not addressed in a ministry publication or the Hydraulic Manual, or when the particular conditions warrant additional research. APPROVAL REQUIREMENTS When considering a design element based on information from another publication, the following approval requirements apply: - If information in one ministry publication is contrary to information in another, the most recently approved shall be the governing standard. Technical Standards Branch must be informed of any discrepancies or ambiguities. - If a design topic is not addressed in the Hydraulic Manual, but is addressed in another publication produced by the Ministry or the U.S. Federal Highway Administration (FHWA) Hydraulic Design Series Number 5 – Hydraulic Design of Highway Culverts and Hydraulic Engineering Circular No.14 – Hydraulic Design of Energy Dissipators for Culverts and Channels, the normal approval authority applies. - If the publication is not listed above, any proposed design element based on that information shall be approved by the same authority as a design exception. See HM 206-00 for more information. Date General Information Page January 31, 2014 1 of 2
  17. 17. Hydraulic Manual HM 202-00 Section: USE OF OTHER PUBLICATIONS Subject: THIS PAGE INTENTIONALLY LEFT BLANK Date General Information Page January 31, 2014 2 of 2
  18. 18. HM 203-00 Hydraulic Manual Section: USE OF PROFESSIONAL JUDGEMENT Subject: INTRODUCTION The guidance and standards in the Hydraulic Manual are intended for application in typical Saskatchewan contexts. Similarly, the guidelines in other publications are intended for certain contexts. It is not possible for any manual or publication to cover every situation that will be encountered in the field. FUNDAMENTAL RESPONSIBILITY The fundamental responsibility of an Engineer is to exercise professional judgement in the best interest of the public. Standards assist engineers in making judgements, but standards are not intended as a substitute for professional judgement. Engineers shall exercise judgement when applying standards and when recommending an exception to a standard. Exceptions to standards require justification and approval. The approval process itself shall not be considered an argument or justification for failing to consider an exception to standards when it is judged to be in the public interest. For more information on the design exception approval process, refer to HM 206-00. Date General Information Page January 31, 2014 1 of 2
  19. 19. Hydraulic Manual HM 203-00 Section: USE OF PROFESSIONAL JUDGEMENT Subject: THIS PAGE INTENTIONALLY LEFT BLANK Date General Information Page January 31, 2014 2 of 2
  20. 20. HM 204-00 Hydraulic Manual Section: DESIGN EXCEPTIONS Subject: INTRODUCTION A Design Exception is defined as any design element differing from the approved ministry standard. See HM 201-00 for more information on approved ministry standards. When a designer uses professional judgement to deem a design exception warranted, the designer shall obtain proper approval for the recommended exception. The process in this section provides the designers with guidelines for obtaining such approval. The purpose of this process is to ensure design exceptions are formally documented, appropriately evaluated and properly approved, as well as providing consistency throughout the Ministry and ensuring standards are kept current. A design exception may apply at any phase of the project; however, approved design exceptions are to be filed with hydraulic design report or approval memo. PROCESS GUIDELINES Step 1. Identify the Key Issue(s) - What are the circumstances that require a hydraulic design element to differ from the current standard? Step 2. Assess various options outside the standard - Identify options that are being considered to address the design exception. - Identify the implications associated with each option. - Consider short-term implications, long-term implications and risk management issues. Step 3. Provide Recommendations - Identify the option that is being recommended - Why was the option selected? Step 4. Submit a report for approval. Step 5. Assess the need for changes to existing standards Date General Information Page January 31, 2014 1 of 2
  21. 21. Hydraulic Manual HM 204-00 Section: DESIGN EXCEPTIONS Subject: - Each design exception should be evaluated by the appropriate Engineering Standards Branch Section to assess whether current standards should be changed. REPORT GUIDELINES Each design exception shall be described in a Design Exception Summary Sheet with a proper signature block. Design Exception Summary Sheets shall include the following: - Project identification and location; - Clear statement of the recommended exception ; - Standard from which the exception differs; - Clear, brief explanation of how and why the exception differs from the standard; and - Signature block. If there are multiple exceptions, they shall be listed in the transmittal memo along with one Design Exception Summary Sheet for each exception. The summary sheets shall be affixed as the cover pages of the Design Exception Report. The Design Exception Report shall include the following: - Introduction (which includes project identification and location); - Identification of the key issues; - Identify and assess the options to address the design exception; - Risk assessment; - Recommendation. APPROVAL The approval of a design exception is subject to the requirements listed in the document Operations Division Signing Authority Delegation (Non-Financial Items). Further to the approval requirements in that document, all non-minor design exceptions shall be reviewed and recommended by the Executive Director of Engineering Standards Branch. The original shall be filed in the Region and one PDF of the approved original shall be sent to the Senior Road Design Engineer, TSB. Date General Information Page January 31, 2014 2 of 2
  22. 22. HM 205-00 Hydraulic Manual Section: USE OF THE TERMS SHALL/SHOULD/MAY Subject: INTRODUCTION The words “shall”, “should”, and “may” will have the following standard meaning when referred to within the Hydraulic Manual. DEFINITIONS Shall: A mandatory condition. No discretion with statements using the stipulation “shall” is allowed. Should: An advisory condition. In statements using “should”, the suggestion is recommended but not mandatory. Deviation from the stated provision is allowed if there is justifiable cause to do so. May: A permissive condition. There is no requirement for design or application of the condition. It is included as an option. NOTE TO USERS Users shall be guided by these definitions. In the event of liability, the courts may place an emphasis on these definitions, which also reflect common English usage of the words. Note also that the traditional grammatical distinction between “shall” and “will” is fading. They are sometimes used interchangeably to convey the same meaning. Date General Information Page January 31, 2014 1 of 2
  23. 23. Hydraulic Manual HM 205-00 Section: USE OF THE TERMS SHALL/SHOULD/MAY Subject: THIS PAGE INTENTIONALLY LEFT BLANK Date General Information Page January 31, 2014 2 of 2
  24. 24. HM 206-01 Hydraulic Manual Section: ROLES AND RESPONSIBLITIES Subject: INTRODUCTION INTRODUCTION The Ministry is made up of many diverse work groups that have different roles and responsibilities within the organization. The purpose of this section is to identify the roles and responsibilities of the work groups with respect to their use of the material contained in the Hydraulic Manual. The Ministry is divided up into the following Divisions: • Ministry Services and Standards Division (MSSD) • Regional Services Division (RSD) • Planning and Policy Division (PPD) • Communications Branch. Currently MSSD and RSD use the Hydraulic Manual. MINISTRY SERVICES AND STANDARDS DIVISION MSSD is divided up into the following Branches: • Financial Services Branch • Corporate Support Branch • Information Management Branch • Technical Standards Branch. The Technical Standards Branch (TSB) is responsible for the design standards and manuals for the Ministry. It is also responsible for providing technical guidance and approvals that are required with respect to the manuals. The Hydraulic Manual is one of these manuals. The details of the roles and responsibilities of TSB is contained in section HM 206-02. The other Branches do not interact directly with the Hydraulic Manual. REGIONAL SERVICES DIVSION RSD is divided up into the following three Regions and the Major Projects Unit: • Northern • Central • Southern • Major Projects Date General Information Page January 31, 2014 1 of 2
  25. 25. Hydraulic Manual HM 206-01 Section: ROLES AND RESPONSIBLITIES Subject: INTRODUCTION The Regions are responsible for the design, installation, rehabilitation, maintenance, and decommissioning of the Ministry’s culverts based on the policies, standards and procedures developed by TSB. The Regions are made up of a number of sections and the details of the roles and responsibilities of each of these sections in hydraulic designs is contained in section HM 206-03. The Major Projects Unit can be involved in the delivery of hydraulic projects for the Regions in addition to work on special projects that have a hydraulic design component. Date General Information Page January 31, 2014 2 of 2
  26. 26. HM 206-02 Hydraulic Manual Section: ROLES AND RESPONSIBLITIES Subject: TECHNICAL STANDARDS BRANCH INTRODUCTION The Technical Standards Branch (TSB) is managed by an Executive Director and is divided up into the following Sections: • Earth Sciences and Research (ES&R); • Design and Traffic Engineering Standards (D&TES); • Construction Standards (CS); • Preservation and Operations Standards (P&OS); and • Bridge Standards (BS). The roles and responsibilities of each section with respect to hydraulic designs are outlined in the sections below. EXECUTIVE DIRECTOR OF TSB The Executive Director of TSB and the Assistant Deputy Minister of Regional Services are responsible for the approval of the Ministry’s Engineering Manuals and Standards. They are also responsible for the approval of design exemptions to these standards. EARTH SCIENCIES AND RESEARCH The Earth Sciences and Research section is responsible for the Ministry’s environmental standards and regulatory agency requirements relating to installation, rehabilitation and maintenance of culverts. The Senior Environmental Engineer position provides training and technical support to the Regions and consultants in this area. The Senior Geotechnical Engineer position is in this section and provides geotechnical design support to the Senior Road Design Engineer, the Regions and consultants with respect to foundation, settlement and slope stability issues relating to culverts. DESIGN AND TRAFFIC ENGINEERING STANDARDS The Design and Traffic Engineering Standards section is responsible for the Hydraulic Manual. The Senior Road Design Engineer position provides training and technical support to the Regions and consultants in the area of hydraulic design. This position also participates in the review and approval process for culvert designs. CONSTRUCTION STANDARDS The Construction Standards section is responsible for standard construction contract specifications and special provisions governing the purchase, installation. Rehabilitation and decommissioning of culverts. The Senior Construction Engineer position provides training and support to the Region on construction specifications. Date General Information Page January 31, 2014 1 of 2
  27. 27. Hydraulic Manual HM 206-02 Section: ROLES AND RESPONSIBLITIES Subject: TECHNICAL STANDARDS BRANCH This section is responsible for the drafting standards for the Ministry. Issues with the Drafting Standards Manual are to be addressed through the Senior Construction Engineer position. This section is responsible for the Consultant Solicitation and Selection Process. This process is managed by the Senior Project Management Engineer position. PRESERVATION AND OPERATIONS STANDARDS The Preservation and Operations Standards section is responsible for the maintenance standards for culverts and the standards relating to the Ministry’s Asset Management System. They are also responsible for the database containing the culvert inventory and condition rating data. The Senior Operations and Preservation Engineer positions provide training and technical support to the Regions on these systems and standards. BRIDGE STANDARDS The Bridge Standards section provides support for the structural design standards for culverts through the Senior Bridge Design Engineer and Director of Bridge Standards positions. The Section also provides support for the standards relating to the inspection and maintenance of bridge sized culverts. The Senior Bridge Asset Management Engineer position provides training and technical support to the Regions on the inspection, maintenance, and condition rating of bridge sized culverts. Bridge sized culverts are culverts equal to and greater than 1.5 m in diameter. They also include wood and concrete box culverts. Date General Information Page January 31, 2014 2 of 2
  28. 28. HM 206-03 Hydraulic Manual Section: ROLES AND RESPONSIBLITIES Subject: REGIONAL SERVICES DIVISION INTRODUCTION Each Region within Regional Services Division is managed by an Executive Director and is divided up into the following sections: • Design and Construction; • Regional Asset Management; • Regional Operations; and • Regional Logistics. The roles and responsibilities of the sections involved with culverts are outlined in the sections below. DESIGN AND CONSTRUCTION The Design and Construction section either undertakes the culvert design and construction contract administration or manages consultants undertaking the work. The Environmental Projects Specialist is to be consulted with for all culvert designs with respect to Saskatchewan Ministry of Environment, the Saskatchewan Watershed Authority and Federal Department of Fisheries and Oceans requirements. The Senior Project Managers are responsible for the following: • Sending PDF copies of all culvert designs to the Senior Road Design Engineer in TSB. • Ensuring that as-built drawings are completed. • Providing the details of all the culvert installations or rehabilitations to the Preservation Planner for the purpose of updating the Culvert Database. • Insuring that culvert markers are installed on through grade culverts. • Reviewing culvert designs to ensure that they comply with the Hydraulic Manual requirements and recommending their approval. • Notifying the Asset Management Group when culverts greater than 1.5 m have been installed so they can be inspected and any defects accepted during construction can be documented. REGIONAL ASSET MANAGEMENT The Regional Asset Management section performs a number of functions related to culverts. The various functions are outlined in the following discussion. Date General Information Page January 31, 2014 1 of 2
  29. 29. Hydraulic Manual HM 206-03 Section: ROLES AND RESPONSIBLITIES Subject: REGIONAL SERVICES DIVISION The Regional Asset Management section is responsible for the development of the capital culvert replacement programs, culvert data collection, and the Culvert Database. The Roadside Development Technicians process permits for roadside development work in the highway right-of-way (ROW). The permits cover the installation of new approaches and any associated culverts. Occasionally the installation of a buried utility in the ROW requires the removal and replacement of a culvert. The Preservation Planner is responsible for the updating of the Culvert Database. REGIONAL OPERATIONS The Regional Operations section performs a number of functions related to culverts. The various functions are outlined in the following discussion. The District Operations Managers (DOM) are responsible for the following: • Review and acceptance of the work covered by the Roadside Development Permits. Where this involves the installation of culverts the DOM is responsible for providing the Preservation Planner with the culvert installation details so that the Planner can update the Culvert Database. • The replacement of culverts managed by the District Maintenance Forces and providing the Preservation Planner with the culvert installation details so that the Planner can update the Culvert Database. • Ensure that culvert markers are installed for all culvert replacements that they have managed. • Ensure that existing culvert markers are maintained. • The routine maintenance of the existing culverts in their district. • The surveillance of existing culverts during and after flooding events. • Documenting the high water levels at culverts resulting from flood events and providing this information to the Preservation Planner so that the Planner can update the Culvert Database. Date General Information Page January 31, 2014 2 of 2
  30. 30. HM 207-00 Hydraulic Manual Section: DEFINITIONS Subject: ABUTMENT A wall supporting the end of a bridge or span, and sustaining the pressure of the abutting earth. ANGLE OF FLARE The angle between the direction of the wingwall and centreline of the culvert barrel. ANNUAL FLOOD The maximum daily or instantaneous peak discharge occurring in a given year. ALLOWABLE HEADWATER ELEVATION The maximum permissible elevation of the headwater at a culvert at the design discharge. APRON Protective material laid on a streambed to prevent scour at a bridge pier, abutment, culvert inlet, outlet, toe of a slope or similar location. ARCH Structural plate corrugated steel pipe formed to an arch shape and placed on abutments. The invert may be natural stream bed or any other suitable material but is not integral with the steel arch. BACKFILL Earth or other material used to replace material removed during construction, such as in culverts, sewer and pipeline trenches, and behind bridge abutments and retaining walls. BAFFLE A flow interference structure, usually in the form of a low weir, which is attached to a culvert invert and extends partially or entirely across the culvert. BASIN SLOPE The average slope of the terrain within a drainage basin. BED LOAD Sand, silt, gravel, rock or other mineral matter which is carried by a stream on or immediately above its bed. COVER The height of fill from the culvert crown to the top of subgrade. CRITICAL DEPTH The depth corresponding to the critical flow. Date General Information Page January 31, 2014 1 of 8
  31. 31. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: CRITICAL FLOW The condition in which flow transitions between streamlined and turbulent, subcritical and supercritical. This occurs when the minimum specific energy is reached. CROWN The highest point of the interior of a pipe at a given cross-section. CULVERT A conduit, usually covered by fill, whose primary function is to convey surface water through an embankment. DAILY DISCHARGE The average discharge occurring over a period of one calendar day. Also termed Mean Daily Discharge. DEPTH OF FLOW The vertical distance to the lowest point of a channel section from the top of the water surface. DESIGN FLOOD OR DESIGN DISCHARGE The maximum discharge a structure is designed to accommodate without exceeding the adopted design. DESIGN FREQUENCY The recurrence interval for hydrologic events used for design purposes. DESIGN HIGH WATER LEVEL The elevation of the level corresponding to the design discharge, but sometimes the level created by other factors such as ice jamming. DISCHARGE The rate of flow of water, usually in cubic metres per second. DITCH A small artificial drainage channel having a definite bed and banks. DRAINAGE Interception and removal of ground water or surface water by artificial or natural means. DYKE An embankment or wall, usually along a watercourse or flood plain, to prevent overflow onto adjacent low land. EMBEDMENT The depth to which a culvert invert is implanted below the average stream bed. END AREA The area calculated on the basis of inside diameter of the available flow area through the conduit. ENERGY LINE A plot showing the total energy along the direction of flow. Date General Information Page January 31, 2014 2 of 8
  32. 32. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: EROSION The wearing away of soil or other material by the action of flowing water or other agents. FILTER A layer of granular material or filter fabric placed over a fine grained material to prevent removal of the fines and at the same time permit the transmission of water. FISH MIGRATION ROUTE A stream used for, or which has good potential for, the seasonal migration of fish. FISH PASSAGE DESIGN DISCHARGE The discharge a culvert must be capable of passing without preventing the upstream passage of fish. FLARED INLET/OUTLET A culvert end treatment designed to improve the hydraulic performance and erosion control of the culvert inlet or outlet. FLOOD A relatively high flow in terms of either water level or discharge. FLOOD FREQUENCY The number of times a flood event occurs or is exceeded during a given period. FLOW Discharge in the channel. FLOW RATE Rate of discharge in the channel. HEAD The height of water above a given datum; the energy of water expressed in metres. HEADWALL A wall at the end of a culvert normally extending from the invert to above the soffit or crown of the culvert, and aligned parallel to the roadway or normal to the longitudinal axis of the culvert. HEADWATER The water upstream from, and whose level is influenced by, a culvert or other structure. HEADWATER DEPTH The depth from the headwater elevation to the invert at the first full cross section of the culvert. HEADWATER ELEVATION The water level upstream from a structure. Date General Information Page January 31, 2014 3 of 8
  33. 33. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: HEIGHT OF COVER Distance from the crown of a culvert or conduit to the finished road surface. HIGH WATER LEVEL The highest level reached by a flood. HORIZONTAL ELLIPSE A long span corrugated steel structure with the major diameter horizontal. HYDRAULIC GRADE LINE A plot showing the pressure head plus the elevation of various points along the direction of flow. HYDRAULIC JUMP An abrupt rise in water surface which occurs when flow changes from supercritical to subcritical. HYDRAULIC RADIUS The ratio of the water area to the wetted perimeter. HYDROGRAPH A graph of discharge or stage versus time at a given point in a drainage system. HYDROLOGY The science dealing with the occurrence, distribution and circulation of water on the earth, in the atmosphere or below the surface of the earth. ICE JAM The choking of a stream channel by the piling up or ice at an obstruction or constriction. ICING The gradual accumulation of ice in a culvert or channel resulting from freezing of seepage flows from groundwater, wetlands or other sources over a period of weeks or months. IMPERVIOUS Impenetrable. Completely resisting entrance of fluids. INFILTRATION The passage of water into the soil or conduit. INLET In culvert hydraulics, an entrance, an orifice, an opening, or a mouth. INLET CONTROL A condition where the flow is governed by the inlet characteristics and the headwater depth. INVERT The stream bed or floor within a structure, conduit or channel. Date General Information Page January 31, 2014 4 of 8
  34. 34. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: INSTANTANEOUS PEAK DISCHARGE The maximum instantaneous discharge occurring during a given flood. INTENSITY- DURATION- FREQUENCY CURVE A curve expressing rainfall intensities for specified durations and frequencies. The data may also be presented in the form of tables or maps. JACKING (FOR CONDUITS) A method for providing an opening for drainage, or other purposes, underground by cutting an opening head of the pipe and forcing the pipe into the opening by means of a horizontal jack. LOCK SEAM Longitudinal seam in a pipe, formed by overlapping or folding of the adjacent seams. MEAN VELOCITY The velocity obtained by dividing the flow rate by the flow area. MITERED END A culvert end the face of which conforms with the face of the embankment slope (often termed a beveled end). NATURAL HYDROGRAPH A hydrograph plotted directly from stream flow records. OPEN CHANNEL A drainage course which has no restrictive top. OPEN CHANNEL FLOW Flow having its surface exposed to atmospheric pressure; the flow may be in an open channel or in a pipe flowing partly full. OPEN FOOTING CULVERT A culvert having either a natural invert of an artificial floor not integral with the walls (also termed open invert culvert). OUTLET CONTROL Flow control at a culvert in which the capacity is governed principally by the barrel roughness, length, slope, and in some cases by the tailwater. PERFORMANCE CURVE A plot of discharge versus headwater elevation or depth at a culvert. PERMEABILITY A property of soils which permits free passage of any fluid. Date General Information Page January 31, 2014 5 of 8
  35. 35. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: PIPE ARCH A corrugated steel pipe or structural plate corrugated steel pipe shaped to a span greater than rise; a multi radius shape with an arch shaped top and a slightly convex integral bottom, structurally continuous with an invert whose radius of curvature is greater than that of the crown. PIPING Subsurface erosion caused by movement of water through fill or natural ground usually associated with a surcharged flow in a pipe. PONDING Water backup in a channel or ditch as a result of a culvert of inadequate capacity or design to permit the water to flow unrestricted. PROJECTING END A culvert end which projects from the face of the embankment. RATIONAL FORMULA A formula for calculating discharge or runoff based on area and rainfall intensity. The formula is Q = C·i·A. REACH A length of stream channel selected for use in computations. RETENTION Temporary natural storage of runoff in lakes and swamps. In urban areas, long term storage for purposes other than reducing flood peaks. RETURN PERIOD The average period of years between flood occurrences equal to or greater than a given value. RING COMPRESSION The principal stress in a confined thin circular ring subjected to external pressure. RIPRAP A layer of stone to prevent the erosion of soil. RISE The maximum vertical clearance inside a conduit at a given transverse section, usually the centerline. ROUGHNESS COEFFICIENT A numerical measure of the frictional resistance of a surface to the flow of water expressed in terms of Manning’s n. RUNOFF COEFFICIENT A coefficient in the Rational formula expressing the ratio of the depth of runoff from a drainage basin to the depth of rainfall, and indicating the runoff potential of a particular soil type/land use combination. Date General Information Page January 31, 2014 6 of 8
  36. 36. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: RUNOFF That part of precipitation carried off from the area upon which it falls. Also the rate of surface discharge of the above. SCOUR Local lowering of a streambed by the erosive action of flowing water. SEAM A joint between two structural steel plates formed by overlapping and bolting them together. Also, the join or lap of riveted corrugated steel pipe (CSP) or the join or weld for continuous weld CSP. SEDIMENT Soils or other materials transported by wind or water as a result of erosion. SEWER A conduit or channel, usually covered, for carrying off the drainage waters and excrements of a town, factory, house, etc. SILL A low wall placed across a culvert or channel to control low flow levels or to stabilize the upstream bed. SOIL-STEEL STRUCTURE A culvert, comprised of structural steel plates and engineered soil, designed and constructed to induce a beneficial interaction of the two materials. SPAN The maximum width of a culvert barrel measured perpendicular to the walls. STAGE The height of a water surface above a specified datum. STATION FREQUENCY ANALYSIS A frequency analysis of flow records at a single stream gauging station. STREAM A body of water flowing in a bed, river, brook or channel. STRUCTURAL PLATE CORRUGATED STEEL PIPE Hot rolled sheets or plate, corrugated, custom hot dipped, galvanized, curved to radius, assembled and bolted together to form pipes, pipe arches, and other shapes. SUMP A storage area at the bottom of a catch basin for trapping sediment. SUPERCRITICAL FLOW Flow at depths shallower than the critical depth. Date General Information Page January 31, 2014 7 of 8
  37. 37. Hydraulic Manual HM 207-00 Section: DEFINITIONS Subject: TAILWATER The water downstream from a culvert or other structure. TAILWATER DEPTH The depth of water immediately downstream from a culvert, measured from the invert of the culvert. UNDERMINE To wash away supporting material from underneath a culvert. This is typically caused by eddies. UNIFORM FLOW Flow in which the velocities are uniform in both magnitude and direction along a conduit, all stream lines being parallel. VELOCITY HEAD The kinetic energy of flowing water expressed in metres. WASHOUT The failure of a culvert, bridge, embankment or other structure resulting from the action of flowing water. WATER COURSE A natural or artificial channel in which a flow of water occurs, either continuously or intermittently. WATERSHED The area of land drained above a given point. Also termed basin, drainage basin, or catchment. WATER SECURITY AGENCY An organization that leads management of Saskatchewan’s water resources to ensure safe drinking water sources and reliable water supplies for economic, environmental, and social benefits for the people of Saskatchewan. WEIR A dam across a river or channel to raise the level of water upstream or regulate flow. WETTED PERIMETER The sectional length of the wetted surface in contact with the flow. The length of the wetted contact between the water prism and the containing conduit. Date General Information Page January 31, 2014 8 of 8
  38. 38. Hydraulic Manual Section 300 Design and Approval Processes 2014
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  40. 40. HM 301-00 Hydraulic Manual Section: DESIGN PROCESS Subject: INTRODUCTION There are approximately 61,000 culverts that the Ministry of Highways and Infrastructure (MHI) is responsible for. This large, aging system is dispersed over a wide geographical area while serving a population of approximately one million people. The design procedures and standards that they are based on are a reflection of this situation and the current Regulatory requirements. The design and approval procedures are influenced by the budget processes used to generate the culvert projects. The culvert projects are part of either the Capital or Operating Budgets. The culverts that are installed under a Provincial Highway or as part of a Capital Road project are part of the Capital Budget. The remaining culverts are part of the Operating Budget. The Capital Budget projects are delivered through the Regional Design and Construction Group while the Operating Budget projects are typically delivered through the Regional Operations Group. There are differences between the processes associated with these groups, and the designer must be aware of the different requirements and properly apply them. Some of the design procedures involve obtaining information or approvals from external agencies and can have significant timelines associated with them. This needs to be recognized and incorporated into the Regions decisions regarding the program development and delivery of culvert projects so that the projects are not unnecessarily delayed. This process includes consultation with the Regional Environmental Project Specialist. The two most important ones are obtaining design flow information from Water Security Agency (WSA), and the determination of whether or not the culvert is required to be designed for fish passage by the Federal Department of Fisheries and Oceans (DFO). These tasks should be undertaken by MHI staff during the program development stage. The design procedure involves a number of steps. The number and content are dependent upon a number of factors. The factors affecting the design procedure and associated use of the Hydraulic Manual are discussed in the following sections. Date Design And Approval Processes Page January 31, 2014 1 of 6
  41. 41. Hydraulic Manual HM 301-00 Section: DESIGN PROCESS Subject: DESIGN AIDS MHI regulates the software used in the design of culverts. Refer to section HM 1000-00 for guidance on the use of design software. DESIGN AND APPROVAL REQUIREMENTS The determination of the appropriate design and approval requirements is the first step in the design process. Refer to section HM 302-00 for the requirements. DOCUMENTATION REQUIREMENTS Proper record keeping is essential to support the approval and quality assurance processes while allowing for the standards development and operational information requirements. The documentation requirements include the proper creation, approval and filing of design reports and the updating of the MHI databases related to culverts. Refer to section HM 303-00 for the procedure to be used COMPILE BACKGROUND INFORMATION The compilation of background data generally involves two sources. The first source of data involves an office search of files where relevant data might be available, and discussion with Maintenance Section staff, Rural Municipality staff, and local residents. A second source involves data that is obtained in the field at or near the site under study and hydraulic structures upstream and downstream. Refer to section HM 400-00 for guidance on the collection of background information. SELECT DESIGN FLOW In most situations the design flow is obtained from WSA and checked against the historical flow conditions at the site. Where this is not possible, the designer must establish a design flow by following the following steps: 1. Design frequency; 2. Flow determination; and 3. Flow frequency. Refer to section HM 500-00 for the guidance on the use of WSA design flows or the establishment of a design flow through other means. Date Design And Approval Processes Page January 31, 2014 2 of 6
  42. 42. Hydraulic Manual HM 301-00 Section: DESIGN PROCESS Subject: ESTABLISH FACTORS AFFECTING CULVERT DESIGN Allowable Headwater Elevation The allowable headwater elevation is the maximum permissible elevation of the headwater at the design discharge. It must account for the necessary freeboard to protect the structural integrity of the road, the elevation of permissible flooding upstream, and any other design considerations which may cause detrimental effects to land, property, or the highway network. Refer to section HM 605-00 for the procedure to be used. Presence of Springs The impact of springs needs to be considered with respect to the buildup of ice that they may cause in culverts and the issues that result during spring thaw and runoff. Tailwater The presence of tailwater influences the capacity of the culvert and the outlet flow velocity and therefore must be properly considered in the culvert design. Refer to section HM 607-00 for the procedure to be used. Stream Profile and Alignment The average stream bed slope needs to be determined to properly set the culvert grade in order to meet the DFO and Ministry of Environment (MOE) requirements. The determination of whether or not the stream is aggrading or degrading is an important part of this process. Streams are typically composed of pools and riffles. The pools occur at the bends and the riffles on the straight sections between them. The presence of bends and riffles introduce a natural undulation into the stream profile which must be taken into account when setting the average stream profile. The average stream profile should be based on the bend elevations or the riffle elevations whichever is the most appropriate for the site. Date Design And Approval Processes Page January 31, 2014 3 of 6
  43. 43. Hydraulic Manual HM 301-00 Section: DESIGN PROCESS Subject: The culvert crossing should try to match the natural stream alignment. Significant realignment of the natural stream channel will require approval from MOE. Department of Fisheries and Oceans It is important that the hydraulic structures on fish migration routes do not restrict fish passage or habitat. The design and construction of hydraulic structures must meet the requirements of the Federal Fisheries Act and any associated Regulations and Measures to Avoid Causing Harm to Fish and Fish Habitat. The Act, Regulations, and Measures to Avoid Causing Harm to Fish and Fish Habitat are administered by DFO. Refer to section HM 900-00 for the fish passage design procedures to be used. The Regional Environmental Project Specialist is to be consulted with for all locations involving fish passage. Transport Canada It is important that hydraulic structures do not restrict navigable waterways. The design and construction of hydraulic structures must meet the requirements of the Navigation Protection Act and any associated Regulations. The Act and Regulations are administered by Transport Canada. The Regional Environmental Project Specialist is to be consulted with respect to the requirements. Water Security Agency WSA is the provincial organization responsible for reviewing aquatic habitat alterations for the protection of aquatic ecosystems and human health. The Environmental Management and Protection Act (EMPA) and The Water Regulations are the responsibility of MOE and define the WSA’s provincial authority for aquatic ecosystem protection and the broader aquatic habitat protection objectives that stem from it, such as the protection of the bed, bank and boundary of Crown surface waters Date Design And Approval Processes Page January 31, 2014 4 of 6
  44. 44. Hydraulic Manual HM 301-00 Section: DESIGN PROCESS Subject: and the values entailed such as aquatic habitat, organisms, the water cycle and shoreline stability. The design, construction and the rehabilitation of hydraulic structures must meet these requirements and require an Aquatic Habitat Protection Permit from WSA. The Regional Environmental Project Specialist is to be consulted with respect to the requirements of the Aquatic Habitat Protection Permit. Utilities The locations of any existing utilities must be determined as part of the design process. If there are utilities present, they must be taken into account in the design. Erosion Control The material type and vegetation cover for the streambed, stream bank, and flood area need to be identified and their permissible mean velocities established. Saskatchewan Environment requires that the streambed, stream bank, and flood area be protected so that the design flow from the culvert does not cause erosion. Refer to section HM 800-00 for the procedure to be used. Camber For culverts installed in high fills and/or yielding ground the effects of the resulting differential settlement have to be taken into consideration in the design. These effects are usually addressed through the introduction of camber in the pipe’s vertical alignment in order to prevent the reduction in capacity, icing and the reduction in service life that may result from ponding water. The Senior Geotechnical Engineer is to be consulted when addressing these design issues. Date Design And Approval Processes Page January 31, 2014 5 of 6
  45. 45. Hydraulic Manual HM 301-00 Section: DESIGN PROCESS Subject: Poor Foundation Soils For culverts installed in frost susceptible or swelling soils additional design measures may have to be taken in order to properly address these situations during the design and construction. The Senior Geotechnical Engineer is to be consulted with when addressing these design issues. Culvert Service Life The Ministry does not have standards for culvert design service life. It is the responsibility of the designer to identify and address local soil and water conditions which would significantly impact the average life of the culvert material being considered for use. The presence of standing water may have a negative influence on the service life of a corrugated steel culvert except for some areas of the Canadian Shield. This situation is usually associated with sloughs containing cattails and the condition can also be created through the embedment of the culvert. SELECT ALTERNATIVES When considering alternatives, the designer should consider all options that are available. The designer shall consider culvert material as well as the various sizes and hydraulic shapes that are available for each material type. ECONOMIC COMPARISON OF ALTERNATIVES After a number of alternatives have been selected based on design flows, the cost of each alternative must be determined. The costs to be included are the cost of the materials and the cost of the installation of the culvert. If the design lives of the alternatives are different, then the cost should be compared on a life cycle or full cost accounting basis. RECOMMENDATION A recommendation must be made after the alternatives have been assessed. This is normally the most economical installation unless there is some reason why a more costly installation is preferable. Date Design And Approval Processes Page January 31, 2014 6 of 6
  46. 46. HM 302-00 Hydraulics Manual Section: DESIGN AND APPROVAL REQUIREMENTS Subject: INTRODUCTION The purpose of this section is to provide the designer with guidance on when a hydraulic design is required or if a historical assessment of the culvert is appropriate for the approval of the installation of new culverts, the replacement of existing culverts, and the sleeving of existing culverts. HYDRAULIC DESIGN REQUIREMENTS New Road Construction Design flows have to be established for all culvert installations associated with new road construction. A hydraulic design shall be undertaken for all crossings except where the design flow condition warrants the installation of a minimum size culvert. This usually occurs where the culvert is located on a small localized drainage area that does not have a defined drainage channel and will not likely have an adverse effect upstream or downstream from the crossing. The hydraulic design report requirements are outlined in HM 303-01. The design ditch velocities should be checked against the permissive velocities, where appropriate, for the ditch soil type and proposed vegetation cover to ensure that there will not be erosion problems from a design flow event. The permissive velocities are outlined in HM 805-00. The ditch design water levels should be checked, where appropriate, against the allowable headwater criteria to ensure that the design criteria are not violated. This is typically required where a stream flows down a roadway ditch. The allowable headwater criteria are outlined in HM 605-00. Road Reconstruction A hydraulic design shall be undertaken for all crossings being replaced when the culvert diameter is equal to or greater than 1500 mm. Date Design Procedures Page January 31, 2014 1 of 4
  47. 47. Hydraulic Manual HM 302-00 Section: DESIGN AND APPROVAL REQUIREMENTS Subject: The hydraulic design report requirements are outlined in HM 303-01. For crossings when the culvert diameter is less than 1500 mm a hydraulic design shall be undertaken when: • A review of the historical performance of the culvert and an assessment of the risk associated with water overtopping the road at that location recommends that a hydraulic design be undertaken; or • Fish passage design is required; or • The crossing involves multiple culverts, or • The culvert is being sleeved. Otherwise the replacement culvert sizing is based on the historical performance of the crossing and an assessment of the risk associated with water overtopping the road. A Hydraulic Approval Memo is required to document culvert replacements where a Hydraulic Design Report is not required. The Hydraulic Approval Memo requirements are outlined in HM 303-02. Culverts Replacing a Bridge. A hydraulic design shall be undertaken. The hydraulic design report requirements are outlined in HM 303-01. Existing Culvert Replacements and Rehabilitation A hydraulic design shall be undertaken for all crossings when the culvert diameter is equal to or greater than 1500 mm or the culvert is being sleeved. The hydraulic design report requirements are outlined in HM 303-01. For crossings when the culvert diameter is less than 1500 mm a hydraulic design shall be undertaken when: • A review of the historical performance of the culvert and an assessment of the risk associated with water overtopping the Date Design Procedures Page January 31, 2014 2 of 4
  48. 48. Hydraulic Manual HM 302-00 Section: DESIGN AND APPROVAL REQUIREMENTS Subject: road at that location recommends that a hydraulic design be undertaken; or • Fish passage design is required; or • The crossing involves multiple culverts. Otherwise the replacement culvert sizing is based on the historical performance of the crossing and an assessment of the risk associated with water overtopping the road. A Hydraulic Approval Memo is required to document culvert replacements where a Hydraulic Design Report is not required. The Hydraulic Approval Memo requirements are outlined in HM 303-02. APPROVAL REQUIREMENTS All new culvert installations, replacements and rehabilitations are approved in the Regions by the Regional Design and Construction Director except for the following situations: • Culvert installations or replacement covered under Approach Permits and Utility Permits which are approved as per the Roadside Management Manual. • Minimum sized approach culverts which are replaced with the same culvert sizes by Operations crews which are approved by the District Operations Manager. • Temporary emergency culvert replacements which are approved by the District Operations Manager. Where any of the following conditions exist, the Hydraulic Design Report shall be reviewed by the Senior Road Design Engineer and recommended by the Senior Road Design Engineer on the approval sheet. • Where the design flow is greater than or equal to 6 m3 /s. • The crossing is required to be designed for fish passage. • The design involves a channel realignment or diversion. • The design involves hydraulic structures to control erosion or water velocity. • The design is part of a pilot project to test new technology, materials, or installation methods. • The design includes non-circular shapes. Date Design Procedures Page January 31, 2014 3 of 4
  49. 49. Hydraulic Manual HM 302-00 Section: DESIGN AND APPROVAL REQUIREMENTS Subject: Design Exceptions Where any culvert design element differs from the approved Ministry standard, the Hydraulic Design Report is approved as per the Signing Authority Delegation – Operations Division (Non-Financial Items). Refer to HM 206-00 for guidance with respect to this. Date Design Procedures Page January 31, 2014 4 of 4
  50. 50. HM 303-01 Hydraulic Manual Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports INTRODUCTION The purpose of this section is to provide the designer with guidance on the creation of hydraulic design reports. HYDRAULIC DESIGN REPORT REQUIREMENTS Hydraulic design reports are required to provide documentation of all hydraulic designs. The hydraulic design report contents outlined in the next section is set up for individual crossings. For new road construction and road reconstruction projects all of the crossings requiring hydraulic designs should be combined into a single hydraulic design report following the outline provided below omitting the information that does not apply. If you are not sure about what to include, contact the Senior Road Design Engineer. HYDRAULIC DESIGN REPORT CONTENTS 1. Recommendation - Provide the final recommendations from the report. - Quick reference for the reviewers. 2. Background Information - Structures/property and special conditions that may impact or be impacted by the design. - Existing road cross-section surfacing structure, cross-slope and widths, sideslope. - Historical performance of the culvert. o Description of existing culvert (length, type, size, material and end treatment) and its condition. o Names of people contacted and their comments. o Copies of relevant information from Ministry files and media sources. o Dates of previous floods and their associated high water levels. o Estimate of the number of years the culvert has been in service. o Document any issues with ice flow blockages or buildup of ice in the culvert. Date Design And Approval Procedures Page January 31, 2014 1 of 6
  51. 51. Hydraulic Manual HM 303-01 Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports 3. Utilities and Regulatory Agencies - Identify all utilities and regulatory agencies. - Locate all utilities and assess their impact on the design. - Special conditions or lack thereof from the regulatory agencies. 4. Design Flow - Return period(s) for design. - Saskatchewan Water Security Agency flow estimates. - Check Water Security Agency flow estimates based on calculation of historical flows at existing structure. - Rationalization of recommended design flows which includes assessment of risk. 5. Design Parameter - This section includes information on the design decisions relating the major design criteria (omit the sections that do not apply to the design). 5.1 Allowable Headwater - Description of the controlling headwater condition and its location. 5.2 Tailwater - Description of the controlling stream tailwater condition and its location. - Description of and justification for the use of hydraulic structures to control the tailwater elevation. - Justification for the embedment of the culverts if used in the design. 5.3 Erosion Protection - Calculation of the outlet apron length. Date Design And Approval Procedures Page January 31, 2014 2 of 6
  52. 52. Hydraulic Manual HM 303-01 Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports - Recommendation of erosion protection material for the sideslope and apron associated with the inlet and outlet and justification for selection. - Description of and justification for use of any special energy dissipating structures. 5.4 End Treatments - Description of and justification for the use of anything other than a projecting end treatment. 5.5 Culvert Alignment - Description of and justification for placing the culvert on a skew angle or shifting the culvert location. 5.6 Stream Channel Realignment - Description of and justification for realigning the stream channel. 5.7 Road Cross-Section and Profile - Description of and justification for changes to the existing road cross-section, sideslope, vertical and horizontal alignment. 6. Selection of Alternative - The following criteria were used in assessing the alternative recommendation. 6.1 (Provide the following summary of the design parameters that are common to all of the design alternatives. Omit any that do not apply. Where the listed design parameter varies with the design alternative, it is to be included in Table 303-1 ) Date Design And Approval Procedures Page January 31, 2014 3 of 6
  53. 53. Hydraulic Manual HM 303-01 Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports Summary Of Design Parameters - Allowable Headwater Elevation = - Design Flow QDesign = - Tailwater Elevation QDesign = - Design Flow QFish = - Tailwater Elevation QFish = - Average Natural Channel Slope = - Natural Channel Status (aggrading, degrading, stable) = - Culvert Slope = - Culvert Manning’s n = - Inlet Elevation = - Outlet Elevation = - Culvert Embedment (depth/%) = - Channel Profile Design Elevation at Outlet = Table 303-1: Comparison of Alternative’s Design Parameters Design Parameter Alternative 1 (Description) Alternative 2 (Description) Alternative 3 (Description) For QDesign Computed Headwater Depth Factor of Safety (QMax*/QDesign) Outlet Flow Depth Outlet Flow Velocity For QFish Computed Headwater Depth Outlet Flow Depth Outlet** Flow Velocity *QMax is the flow with the headwater set to the road overtopping point. **Use the higher of the inlet and outlet flow velocity when culvert under inlet control. 6.2 Cost Analysis - Summarization of the costs for alternatives evaluated. Date Design And Approval Procedures Page January 31, 2014 4 of 6
  54. 54. Hydraulic Manual HM 303-01 Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports 6.3 Selection of Alternatives - Identify any alternatives that were considered but did not make the short list of alternatives that were analyzed in detail. - Provide the reasoning for the recommended alternative. Appendices Appendix A: Water Security Agency Correspondence On Design Flows Appendix B: Regulatory Agency Correspondence Appendix C: CulvertMaster Culvert Designer/Analyzer Reports Appendix D: CulvertMaster Culvert Calculator Reports Appendix E: Cost Estimates Appendix F: Photographs Appendix G: Plans 1. Location Plan 2. Construction Operation Plan 3. Road Cross-Section Detail Plan 4. Installation Typical Cross-Section Plan 5. Erosion Protection Plan 6. Streambed Profile Plan 7. Highway Centerline and Ditch Profile Plan 8. Stream Cross-Section Plan Note: The DFO Copy of the Report does not contain Section 6.2 - Cost Analysis. Date Design And Approval Procedures Page January 31, 2014 5 of 6
  55. 55. Hydraulic Manual HM 303-01 Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Design Reports REPORT DISTRIBUTION The distribution of the approved hydraulic design reports shall be as follows: One signed original filed in the Region, and one PDF copy of the original signed report to TSB. Where fish passage is required, a third signed copy of the report may be required for submission to DFO. Date Design And Approval Procedures Page January 31, 2014 6 of 6
  56. 56. HM 303-02 Hydraulic Manual Section: DOCUMENTATION REQUIREMENTS Subject: Hydraulic Approval Memo INTRODUCTION Purpose To provide the designer with guidance for Approval Memos. Scope The Memo covers individual culvert replacements, and culvert replacements included in highway reconstruction or upgrading projects. A group of culverts can be included into a single approval report. CULVERT APPROVAL MEMO CONTENTS 1. Recommendation. 2. Declaration (Use the following statement) The culvert(s) historical performance had been reviewed and used as the basis for determination of the new culvert size. 3. Analysis: Documentation of justification for recommending an increase in the culvert size. 4. Culverts Covered Under Approval: Table listing the control section, at km, existing culvert size, existing culvert type existing culvert material, replacement culvert size. 5. Approval Block. Appendices: Include any documentation to support Section 3 analysis. MEMO DISTRIBUTION The distribution of the approved hydraulic approval memos shall be as follows: One signed original filed in the Region. Date Design And Approval Procedures Page January 31, 2014 1 of 2
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  58. 58. Hydraulic Manual Section 400 Background Data Collection 2014
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  60. 60. HM 401-00 Hydraulic Manual Section: BACKGROUND DATA COLLECTION Subject: INTRODUCTION A successful culvert design relies on historical site information and sufficient field data collection. In support of the culvert design, site field data collection should provide enough information for designers to determine channel and floodplain geometry, adjacent structures which may affect the hydraulics of the structure, adjacent crossings, soil types, evidence of scour, and natural obstructions. DATA REQUIREMENTS The following data collection requirements are for the preparation of hydraulic designs. Where full hydraulic designs are not required the data collection requirements should be amended to reflect the scope of the project being undertaken. Historical Site Data The historical site data consists of previous hydraulic design reports and information on previous high water levels contained in MHI Library, Technical Standards Branch, Region and District paper and electronic files. It is to be obtained through discussion with District Maintenance Section staff, Rural Municipality staff and local residents. Historical site data consists of the following information: • Dates and high water levels of previous flood events. • If the water flowed over the road, the location, depth and width of the water at its peak and the length of time that water was flowing over the road. • The period of time that information covered. For example, the flood data was obtained from observations covering the time period from 1990 to 2011. • Information on the presence of springs and any historical issues with icing up of the culvert or ice flow blockages during the spring runoff. Field Data Requirements The designer shall visit the site before or with the survey crew in order to determine if additional measurements are required due to the existing site conditions. During the site inspection, the designer will take the following set of standard pictures plus additional pictures as Date Background Data Collection Page January 31, 2014 1 of 8
  61. 61. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: required or make clear sketches. The photos should be taken with a GPS enabled camera. If thick vegetation is present at the location, the crew should be notified as it may interfere with their GPS survey equipment. All survey points shall be referenced to a geodetic bench mark. Photographs: • Structure o Panorama picture of the inlet from property line to property line taken from the property line. o Standard picture of the inlet from the property line. o Close up of the inlet. o Picture of inside of inlet showing condition of the structure. o Panorama picture of the outlet from property line to property line taken from the property line. o Standard picture of the outlet from the property line. o Close up of the outlet. o Picture of inside of outlet showing condition of the structure. • Fence lines • Road(s) o Panorama picture of the road from the centre of the structure looking up change from property line to property line. o Standard picture of road, from the centre of the structure looking up chainage. o Panorama picture of the road, from the centre of the structure, looking down chainage from property line to property line. o Standard picture of road, from the centre of the structure, looking down chainage. o Pictures of ditch blocks, field approaches and intersecting roads within 250 m of the site. Include pictures of the inlet and outlet of any culverts installed in them. • Stream o Panorama picture of the stream, taken from the edge of Date Background Data Collection Page January 31, 2014 2 of 8
  62. 62. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: the road shoulder, looking up stream from edge of road to edge of road. o Standard picture of stream looking up stream. o Panorama picture of the stream, taken from the edge of the road shoulder, looking downstream from edge of road to edge of road. o Standard picture of stream looking downstream. o Picture of stream bottom material (if visible). o Picture of the stream at each cross-section location. • Section lines. • Utilities. • Upstream man-made structures that potentially could be flooded. • Scour holes and any stream obstructions such as beaver dams within 400 m of the structure. • Landmark. Notes to record in survey file: • Direction of flow if it is obvious. • Height and width of opening under bridges or wood box culverts. Measure the height of the opening at the backing on both sides and in the channel at the deepest point. This will help in selecting the size of the new structure. • Make a note as to whether profiles or typicals continue to rise or drop after end shots. • Complete set of transit notes. • Note whether or not farmyards are occupied. Existing Road Centreline Profile: • The profiles shall be a minimum of 250 m in length in each direction from the existing structure. The profile should go far enough in each direction to establish the location of the low point on the highway in relation to the drainage basin and facilitate setting a gradeline, if a grade raise is required. • Shots at least every 25 m. Date Background Data Collection Page January 31, 2014 3 of 8
  63. 63. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: Existing Ditch Profiles: • Shots at least every 25 m carrying the shots through the stream channel. Additional shots shall be taken to establish the channel cross-section. The profile should go far enough to get elevation higher than highway centerline at structure. • Make sure the profile establishes the crests in the ditches. • The profiles shall be at least 250 m in length in each direction from the existing structure. Natural Ground Profiles: • The profiles shall be a minimum of 250 m and go far enough to capture dips where water could run out of the ditch. • Shots at least every 25 metres. Take additional shots at low points and crests. • Take the profile outside of the ditch and close to the edge of the right-of-way in order to have a profile of the natural ground slope running into the streambed. Streambed (Thalweg) Profile: • The profile shots shall be taken at the lowest part of the stream channel. • The profile shall be at least 300 m to 400 in each direction from the existing structure. The profile should go far enough to establish direction of flow (extend profile to achieve a drop or rise of approximately 1 m in each direction where the terrain is flat). • Shots shall be taken at every change of direction (include enough shots to show the shape of the bends) and change of elevation in the channel. • The first shot is to be at the end of the structure. Shots shall be taken at a 1 m interval from the end of the structure to the property line. This will allow the definition of any existing scour holes, and will aid in establishing invert and outlet apron elevations for the new structure. • Take extra shots immediately before and after any obstructions Date Background Data Collection Page January 31, 2014 4 of 8
  64. 64. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: (note type in survey notes) in streambed. Also take a shot on top of obstruction as well as enough shots to show its shape. (examples, beaver dams or rock riffles) Streambed Typical Cross Sections: • All stream bed cross-sections shall be taken perpendicular to the stream channel. As a minimum for narrow channels, shots shall be taken on the bottom of each edge and the mid-point of the channel along with the top of the bank. For wider channels additional points are to be taken in order to give an accurate representation of the channel bottom shape. If the bank goes up in steps, additional points are to be taken in order to give an accurate representation of the bank and its top shape. The cross-sections have to extend far enough to include the top of the flood plain and the “Ordinary High Water Mark”. This is usually the edge of the pine trees in northern areas. In other parts of the province where the flood plain is wide and flat the cross-section shall extend for 100 m. • The lowest point on the cross-sections shall be included as points on the stream channel profile. • A typical cross-section shall be taken at the edge of the right- of-way downstream from the structure where there is no bend in the channel within the right-of-way. Where the channel bends and flows within the right-of-way, cross-sections are to be taken at the start, mid-point and end of each bend and every 15 m along the along the tangent sections. • Cross-sections are to be taken at the start, mid-point and end of the first two bends in the channel downstream from the edge of the right-of-way and every 25 m on tangent from the edge of the right-of-way till the start of the third bend. If the third bend is further than 400 m the last cross-section is to taken at the end of the stream channel profile. If the distance between the bends is less than 25 m the tangent cross-section shall be taken at the midpoint between the two bends. • Take cross sections at all channel obstructions for 100 m upstream and 500 m downstream. The cross sections must be taken on top of the obstructions and in the natural channel either before or after the obstructions. Date Background Data Collection Page January 31, 2014 5 of 8
  65. 65. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: Roadway Typical Cross Sections (Min.4): • Take a typical cross section on each side of the existing structure. Take it as close to the existing structure as possible, keeping it away from the wingwalls and outside the steam channel. • Take a typical cross section on one side of the existing structure showing the ditch cut. • Typicals should extend far enough to pick up beyond the ROW edge and be on natural ground. • Cross sections at structure centre, piers, abutments and shots at every 8 m and the key elevations: Centerline, lane and pavement edge, pavement bottom, shoulder edge, deck curb, sideslope break, crown, invert, and stream bed. Water Levels: • Present Water Levels on both sides of existing structure. If there is a strong flow take the shots approximately 20 m from centreline. Also if there is an obstruction in this area, take a shot just before and after the obstruction to establish the new PWL. • High Water Level (HWL) on the upstream side of existing structure. A couple of ways to determine the HWL is to look for scouring on bridge piles or fence posts. Look for differences in growth on the banks of the streambed. • Average Water Level. This is where the normal vegetation in the area changes to aquatic vegetation. Usually this is fairly obvious and follows the stream bed and will be at a relatively consistent elevation Miscellaneous: • All through grade and approach culverts must be shot and sizes recorded. • Tie in all dry approaches including shots on the lowest part of the approach. Utilities: Date Background Data Collection Page January 31, 2014 6 of 8
  66. 66. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: • Tie in all visible utilities, above and below ground. Upstream Development: • Look for manmade structures upstream which may affect the allowable headwater (houses, barns granaries, etc.). Obtain ground surface elevation at the base of the structure. Existing Structure: • Shots on the corners of the wood box culverts. Making sure the shots represent the elevations of the wood planking. • Measurement of the height and width of the clear opening of the wood box culvert. • Inverts of culvert. For wood box culvert the elevation at the mid-point of the cross-sill at the end of the wood box and the inlet and outlet aprons. BRIDGE STRUCTURE If the structure identified for replacement is a bridge, a grid type survey should be completed. This type of survey will be required if the existing bridge must be replaced by a bridge. For bridge survey, the following information needs to be recorded in addition to the above requirements. Existing Road Centreline Profile: • Shots on top of existing surfacing at centreline of roadway and at both edges of pavement. Take shots at both abutments and at all piers. Include the centreline shots on the centreline profile. Provide elevation, stationing and offset for each point. As per attached drawing “Bridge Survey”. • Take shots on top of the concrete or timber decking just outside the edge of the pavement. Take shots at both abutments and all piers. Provide elevation, stationing and offset for each point. As per attached drawing “Bridge Survey”. Date Background Data Collection Page January 31, 2014 7 of 8
  67. 67. Hydraulic Manual HM 401-00 Section: BACKGROUND DATA COLLECTION Subject: Flood Plain Typical Cross Sections: • Channel cross-sections at the inlet and outlet of the bridge. o Take cross-sections as close to the bridge as possible on natural ground. i.e. cross-sections should not include points influenced by the bridge, ditch or roadway. o Cross-sections are to extend 100 m each way from the centre of the stream. Provide stationing and elevation for each point shot. Stationing for the cross-sections must be tied to the roadway centerline profile stationing. • Channel bed profile. o The profile is to extend 200 m upstream and downstream from the centerline of the roadway. o Take shots along the bottom of the channel bed at 20 m spacing. Provide stationing and elevation for each point shot. Indicate the channel bed spacing at the centre of the bridge. • Minimum of 100 m in all 4 directions (parallel and perpendicular to the channel) and the cross section should be every 25 m, and at stream obstructions and changes in gradient. Starting the shots as close to the bridge as possible but on natural ground. • Take enough shots to produce an accurate contour plan for the bridge location with 0.1 m intervals. Contours at 0.5 m are to be labeled. Generally contours should include an area 100 metres upstream and downstream from the bridge and 100 metres each way from centre of the channel. Date Background Data Collection Page January 31, 2014 8 of 8
  68. 68. Hydraulic Manual Section 500 Design Flows 2014
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  70. 70. HM 501-00 Hydraulic Manual Section: DESIGN FLOW METHODOLDGY Subject: INTRODUCTION Hydrology in its broadest sense is the study of water and addresses its occurrence, distribution, movement and chemistry. The design and operation of hydraulic structures relies on hydrology for the determination of the design flows that they must accommodate. This section presents the Ministry’s methodology and components involved in its implementation. There are three main components involved in establishing a design flow: 1. Design frequency; 2. Flow determination; and 3. Flow frequency. The processes associated with the above components are outlined in the sections below. METHODOLOGY Design Frequency The first step in the determination of the design flow is the establishment of the appropriate design frequency. The criterion for this is contained in section HM 502-00. Flow Determination The second step in the determination of the design flow is the establishment of the appropriate design flow for the chosen design frequency. In Saskatchewan, the Water Security Agency (WSA) is the Provincial authority in the field of hydrology. The Ministry does not have the resources to have full time hydrologists on staff, so it relies on the WSA for the determination of the design flows used in the design of hydraulic structures. The diverse topography of Saskatchewan is the result of glacial actions and is considered unique in the world. Because the resulting Date Design Flows Page January 31, 2014 1 of 4
  71. 71. Hydraulic Manual HM 501-00 Section: DESIGN FLOW METHODOLOGY Subject: topography is different than the rain erosion based topographies common to the United States and other parts of Canada, its impact must be considered in the choice of the methodology used to estimate the design flow. Of particular significance is the typical large amount of “prairie pothole” depression storage contained in the effective contributing areas of the basin in the central and southern parts of the Province. The amount of water stored in these areas varies throughout the year and between years. Depending upon the water level the same rainfall or spring runoff event can produce anything from no runoff to a flood. Within the field of hydrology there are two main methods for the establishment of a design flow for a specified design frequency. The methodologies are based either on the analysis of historical rainfall or snowfall data or are based on the analysis of historical stream gauge data. In central and southern Saskatchewan, care must be taken when using snow gauge data because the snow cover can drift for large distances in these parts of the Province. This has a significant impact on the resulting spatial distribution of the snow. Therefore, snow pack measurements or historical information on the snow pack in a drainage basin is preferable to the use of snow gauge data alone. The Ministry has standardized on the use of historical stream gauge data for the determination of design flows because it reflects the output of all of the related design factors, including those impacted by the topography. To address all of the impacts on the input side using the rainfall based design methodologies would be a significantly more complicated and expensive process. The WSA uses the following method to determine design flows. Generally, the situations they encounter involve one of three types: • Locations with long term records; • Locations with short term records; or • Locations with no records. Date Design Flows Page January 31, 2014 2 of 4
  72. 72. Hydraulic Manual HM 501-00 Section: DESIGN FLOW METHODOLOGY Subject: At culvert crossings located in basins with a gauging station with long term records, the flow data is taken directly from the gauge station records. The design flows are typically transposed from the full basin to the sub-basin containing the culvert crossing. At locations where short term information is available, this information is integrated with a nearby location where long term data is available. From this, the design discharges are determined. For locations where no data is available, the design flows are transposed from nearby basins with similar characteristics and are based on contributing areas. The WSA provides a mean daily flow estimate for the site under consideration for the following flow frequencies: 1:2, 1:10, 1:25, 1:50 and 1:100 along with a peaking factor. The mean daily flow is multiplied by the peaking factor to determine the instantaneous peak flows. The WSA flow calculations carry a degree of variability. The amount of variability depends upon the relationship of the drainage basin to the basins that have gauging stations on them in the Province. Because of the variability, the Ministry requires that all of the WSA estimates be validated as being reasonable using a second approved method. The following methods are to be used. They are listed in order of preference and reliability. • Flow through an existing structure at the study site based on an analysis of the historical headwater levels; • Flow through an existing structure upstream or downstream of the site based on an analysis of the historical headwater levels; and • The Rational Method. The analysis procedure for the above methods is contained in sections HM 503-01, HM 503-02 and HM 503-03 respectively. For drainage basins smaller than 25 km2 SWA may not be able to provide a flow estimate due to the accuracy issues involved in their Date Design Flows Page January 31, 2014 3 of 4
  73. 73. Hydraulic Manual HM 501-00 Section: DESIGN FLOW METHODOLOGY Subject: methodology. They will let the designer know if this is the case when responding back to the request. When this occurs, the Designer will have to use one of the alternative methodologies listed above. In some situations WSA may not be able to respond in a timely manner with a flow estimate. This can be avoided by requesting design flows early in the culvert replacement programming cycle. When this cannot be avoided, the designer can obtain the gauging data from SWA and utilize the transposition of flow methodology contained in section HM 503-04. FLOW FREQUENCY When a flow is determined using a historical headwater level at existing structures, it must be assigned a frequency. Some judgment must be used to determine that flow frequency. The methodology to do this is contained in section HM 504-00. FLOW CONVERSION The calculated flow frequency, as determined above, must next be converted to the design frequency. The methodology to do this is contained in section HM 505-00. CULVERTS REPLACING BRIDGE STRUCTURE Where a bridge is being replaced with culverts, the design flow to be used for the new design should equal or exceed the existing bridge capacity Date Design Flows Page January 31, 2014 4 of 4
  74. 74. HM 502-00 Hydraulic Manual Section: DESIGN FREQUENCY Subject: INTRODUCTION This section outlines the various design flow frequencies that are used in culvert and bridge hydraulic designs. The designer must use care to ensure that they are using the correct values since instantaneous peak flows are used for culvert designs and maximum mean daily flows are used for bridge designs. The design flow frequency for fish passage is contained in section HM 900-00. INSTANTANEOUS AND MEAN DAILY FLOWS The difference between instantaneous peak flow and mean daily flow is the time period over which the flow is averaged and the magnitude of the peaking factor is a function of the characteristics of the drainage basin. The mean daily flow is averaged over an entire day, whereas the peak instantaneous flow is averaged over a matter of minutes. This is illustrated in Figure 502-1. The shape of the curve is dependent upon the physical characteristics of the drainage basin. This can result in the maximum mean daily flow and the peak instantaneous flow being roughly equivalent or the peak instantaneous flow may be three times or greater than the max mean daily flow. Figure 502-1 –Typical Natural Hydrograph (SWA, 1962) Date Design Flows Page January 31, 2014 1 of 2
  75. 75. Hydraulic Manual HM 502-00 Section: DESIGN FREQUENCY Subject: MEAN ANNUAL FLOW The Mean Annual Flow (Q2.33) is the average volume of water to flow through a stream per year. As such, it is a mean daily flow. It is also referred to as the bankful flow. Generally, it is the flow that defining the change from aquatic to terrestrial vegetation along the stream bank. DESIGN FLOW The design flow for culverts use an instantaneous flow, whereas the design flow for bridges uses a mean daily flow. Refer to Table 502-1 for design flows for culverts and Table 502-2 for bridges. Table 502-1: Culvert Design Flow Frequencies Class of Road Design Frequency (Instantaneous Peak Flow) National Highway System 1/50 All Other Provincial Highways & Provincial Roads 1/25 Other Roads 1/5 to 1/10 Table 502-2: Bridge Design Flow Frequencies Class of Road Design Frequency (Maximum Mean Daily Flow) Provincial Highways and Provincial Roads 1/50 to 1/100 Other Roads 1/25 The design frequency shall be increased to 1/100 where a community or area of the province would be isolated by the highway being overtopped or washed out due to hydraulic structure failure. Consideration should be given to increasing the design frequency to 1/100 for structures where extreme flooding conditions could cause excessive damage to a community immediately upstream of the culvert crossing. Note that this does not apply to individual farmyards. The protection of farmyards is governed by the allowable headwater design criteria contained in section HM 605-00. Date Design Flows Page January 31, 2014 2 of 2
  76. 76. HM 503-01 Hydraulic Manual Section: FLOW CALCULATION Subject: EXISTING STRUCTURES AT SITE INTRODUCTION The most reliable method to determine the design flow at a location is by determining the high water history of an existing installation. Valuable information can be obtained from an on-site inspection as well as interviews with local Ministry personnel, Rural Municipality staff and residents. HIGH WATER LEVEL The historical high water levels of past floods and the years that they occurred in should be determined along with the estimated age of the culvert. Past high water levels may also be indicated in the field by high water marks such as ice scars on trees, debris and high water lines on crossing structures, earth surfaces or buildings. In addition to the interview and field information, a check of Ministry files may yield useful information at a particular location. If a problem has occurred at a site, it may be noted on the file along with the high water level and the year it occurred in. Once the high water level has been determined, an effort should be made to ensure that this high water level was not the result of a circumstance other than a capacity problem. It is possible that icing could have partially obstructed the barrel of the culvert, or debris could have partially obstructed the culvert opening. This can be checked by comparing flows with flows at upstream and downstream structures. TAILWATER The tailwater elevation is determined based on site survey data and field observation of conditions that may affect the tailwater elevation. If survey data is not available, then field observation will have to be used to estimate a tailwater elevation and checked by doing a sensitivity analysis of the crossing using the Quick Calculator mode in CulvertMaster. FLOW CALCULATIONS Once the high water level is known and the tailwater condition has been determined, it is possible to determine the discharge associated with the historical high water level events. Date Design Flows Page January 31, 2014 1 of 2
  77. 77. Hydraulic Manual HM 503-01 Section: FLOW CALCULATION Subject: EXISTING STRUCTURES AT SITE FLOW THROUGH BRIDGES Through the use of Manning’s Formula, it is possible to develop a velocity for flow in a natural channel. With the calculated velocity, and channel area, a discharge can then be calculated. However, this formula often results in velocities that are too high for Saskatchewan conditions. A rule of thumb for flow under bridges is to use a velocity of 1.2 m/s to 1.5 m/s multiplied by the area under the bridge. Scour immediately downstream from the bridge usually indicates that a higher value should be used. In this case the rule of thumb is to use a velocity of 1.5 m/s to 1.8 m/s. Designers are also advised to check with the Senior Bridge Project Manager in the Asset Management Section in their respective region since they have cross-sections of the stream channel on each side of the bridge that are taken during each bridge inspection. They may also have a record of design flows and unusual flows on file. DETERMINING DESIGN FLOW After a flow has been determined at an existing structure, it must be assigned a frequency and converted to a design frequency. Refer to section HM 504-00 and section HM 505-00 for the procedures to do this. Date Design Flows Page January 31, 2014 2 of 2
  78. 78. HM 503-02 Hydraulic Manual Section: FLOW CALCULATION Subject: STRUCTURES UPSTREAM AND DOWNSTREAM INTRODUCTION Situations occur where data from structures other than the location under consideration should be used. An example is where a highway is being constructed on a new location across a drainage run. Design flows can be obtained from structures upstream or downstream from the proposed installation on the same drainage run. Another example is when a high water level is known at a site upstream or downstream of an installation. This can be used to determine the design flows at the site or to check the design flow being used at the site under study. FLOW AT STUDY SITE Flow at Other Structures The first step involved in determining the flow at the study site is to determine the flow at the structure upstream or downstream from the study site. This is done by following the same procedure as for Existing Structures at Site outlined in section HM 503-01. Additional Flow The second step is to determine the flow that must be added or subtracted to the flow calculated above. The typical method is the method of transposition. First, the effective area contributing to the project site is calculated and then the effective area contributing to the other structure area is determined. Finally, the method of transposition described in section HM 503-04 is used to determine flow at the project site. If the Rational Method is being used, the following process should be followed. First, the additional contributing area can be determined from a topographic map. Next, a runoff coefficient can be obtained from HM 503-03. Finally, intensity can be obtained from Intensity- Duration-Frequency (IDF) charts and a discharge can be calculated. IDF charts are available from Environment Canada’s “National Climate Data and Information Archive” website. The discharge is either added or subtracted from the calculated flow at the upstream or downstream structure. Date Design Flows Page January 31, 2014 1 of 2
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