Hydraulic Manual (Dec 2014)

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

Hydraulic Manual HM 001-00
Section:
CHANGE HISTORY
Subject:
Date
Introduction
Page
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.

HM 002-00
Hydraulic Manual
Section:
TABLE OF CONTENTS
Subject:
Date Page
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

Section:
TABLE OF CONTENTS
Subject:
Date Page
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

Section:
TABLE OF CONTENTS
Subject:
Date Page
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
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
HM807-01: Riprap Pipe Culverts 600 mm < D < 1500 mm
900-00 Fish Passage Design Procedures
901-00 Fish Passage Design Procedures

Section:
TABLE OF CONTENTS
Subject:
Date Page
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

Hydraulic Manual
Section 100
Introduction
2014

THIS PAGE INTENTIONALLY LEFT BLANK

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

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

Hydraulic Manual
Section 200
General Information
2014

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
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Section:
USE OF THIS MANUAL
Subject:
Date
General Information
Page
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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
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Section: USE OF OTHER
PUBLICATIONS
Subject:
Date
General Information
Page
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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
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Section: USE OF PROFESSIONAL
JUDGEMENT
Subject:
Date
General Information
Page
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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
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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
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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
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Section: USE OF THE TERMS
SHALL/SHOULD/MAY
Subject:
Date
General Information
Page
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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
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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
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HM 206-02
Hydraulic Manual
Section:
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.
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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.
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HM 206-03
Hydraulic Manual
Section:
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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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.
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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
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Hydraulic Manual
Section 300
Design and Approval Processes
2014

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.
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Design And Approval Processes
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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.
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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.
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.
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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
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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.
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
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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
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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
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REQUIREMENTS
Subject:
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.
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.
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
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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
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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
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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.
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REQUIREMENTS
Subject:
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.
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REQUIREMENTS
Subject:
- 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 )
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REQUIREMENTS
Subject:
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.
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REQUIREMENTS
Subject:
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.
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REQUIREMENTS
Subject:
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.
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HM 303-02
Hydraulic Manual
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
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REQUIREMENTS
Subject:
Hydraulic Approval Memo
Date
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Hydraulic Manual
Section 400
Background Data Collection
2014

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
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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
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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.
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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
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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
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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:
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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”.
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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
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Hydraulic Manual
Section 500
Design Flows
2014

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
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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.
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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
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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
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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
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Page
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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
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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
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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
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Page
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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
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Hydraulics Manual HM 503-02
Section:
FLOW CALCULATION
Subject: STRUCTURES UPSTREAM AND
DOWNSTREAM
Date
Design Flows
Page
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