 Subsurface Utility Engineering is a branch of engineering practice that involves managing risks associated with existing underground utilities. Combining geophysics, surveying and civil engineering a SUE investigation is a valuable component of any capital works project or asset management program. SUE provides accurate mapping of underground utilities that aids project designers avoid costly conflicts and allows them to properly plan for utility relocations to minimize project delays. TSH/TBE can provide utility mapping, utility coordination and utility design to help your project run as smoothly as possible.
Please follow the links on the side navigation of this page to learn more about SUE.
SUE Process
Subsurface Utility Engineering is a process that is unique to each project and the scope of the investigation often evolves as the overall project progresses towards construction. For each project the SUE provider systematically identifies what quality of utility information is required for the design, how best to collect the information and how to manage the information. While no project is the same, typically the following tasks will be performed:
- Scope of Work – The process of developing a written project specific work plan that consists of scope of work, levels of service, project schedule and desired project deliverables. The work plan is agreed upon by the SUE provider and the client.
- Record Research – The process of collecting and reviewing available utility records information for the project area.
- Designating – The process of using surface geophysical methods to determine the presence of subsurface utilities and to mark their horizontal position on the ground surface.
- Locating – The process of exposing and recording the precise horizontal and vertical position of subsurface utilities generally using a vacuum excavation technique.
- Data Management – The process of surveying the utility information and presenting the information in a CADD or GIS format.
- Conflict Analysis – The engineering process of using a conflict matrix to evaluate and compare collected utility information with the client’s proposed plans to identify and inform all stakeholders of potential conflicts, potential solutions and costs to solve the conflicts.
ASCE Standard
In 2003 the American Society of Civil Engineers (ASCE) published a document titled “Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data”. The standard defined SUE and set guidance for the collection and depiction of subsurface utility information.
This ASCE standard presents a system to classify the quality of existing subsurface utility data. The classification allows SUE providers, engineers, constructors and project owners to manage utility related risks due to existing utilities. Utility information that is collected and presented following this classification system can be readily interpreted by a user familiar with this standard. The standard defines four Quality Levels of utility data. The different levels are described below:
- Quality Level D – Information derived from existing records or oral recollections.
- Quality Level C – Information obtained by surveying and plotting visible above-ground utility features and by using professional judgement in correlating this information to Quality Level D.
- Quality Level B – Information obtained through the application of appropriate surface geophysical techniques to determine the existence and approximate horizontal position of subsurface utilities.
- Quality Level A – Information obtained by exposing and measuring the precise horizontal and vertical position of a utility at a specific point.
To order a copy of the standard from the ASCE website, please click here.
When to use SUE
SUE can be used anytime you need information about utilities. The two main applications of SUE are at the design stage of capital works projects or to collect accurate information for an asset management project. The process followed is essentially the same regardless of the application. The difference is in scope of work and the use and presentation of the information.
When a SUE investigation is carried out for a capital works project prior to construction the main goal of the investigation is to collect accurate utility information in the project area to avoid unwanted utility issues later on in the project. In this type of application the geographical area of the project is usually well defined and the key is collecting enough information to reduce the utility related risk to an acceptable level.
In an asset management application, the project owner is often missing information about their underground utilities or realizes that information they have is flawed or incomplete. In this situation the SUE provider would collect the required information to add to the asset management database. The Quality Levels described in the ASCE Standard can be used as a data attribute in the database so the user of the database knows how the utility information was collected.
Benefits of SUE
A properly planned and executed SUE investigation provides many benefits to the project owner including fewer project delays and lower overall project costs. Having reliable utility information allows the project designers to make informed decisions resulting in the following potential benefits:
- Reduced project delays and costs caused by waiting for utility relocation work to be completed;
- Reduced project delays and costs caused by waiting for redesign when construction cannot follow the original design due to unexpected utility conflicts;
- Reduced delays to contractors during construction caused by damaging or discovering utility lines that were not known to be present in the project area;
- Reduced number of conflicts and relocations because the designer has the ability to design around utilities when feasible.
Three different studies have been carried out to investigate the benefits of using a SUE investigation at the design stage of construction projects. Read more about these studies in the SUE STUDIES section below.
SUE Studies
University of Toronto SUE Study
The Ontario Sewer and Watermain Contractors Association commissioned the University of Toronto to investigate the practice of using SUE on large infrastructure projects in Ontario. The study chose nine case studies and determined that the average rate of return for each dollar spent on SUE services on these projects was $3.41. The study also made a number of qualitative recommendations regarding the use of SUE.
Free copies of the report titled “Subsurface Utility Engineering in Ontario: Challenges and Opportunities” can be obtained from the Centre of Information Systems in Infrastructure and Construction website. Click here to obtain your copy.
Purdue University SUE Study
The Federal Highway Administration (FHWA) commissioned Purdue University to determine how effective SUE is at reducing costs on highway projects. The study selected 74 highway projects from across the USA and determined that on average every dollar spent on a SUE investigation resulted in $4.62 of project savings. Out of all the projects only three had a negative return on investment.
Free copies of Purdue’s January 2000 report “Cost Savings on Highway Projects Utilizing Subsurface Utility Engineering” may be obtained from the FHWA. Click here to obtain your copy.
Stevens Paper
An investigation by R.E. Stevens, presented at the International Conference of the Society of American Value Engineers, showed that the use of SUE services resulted in overall project savings of 10-15%.
Free copies of the paper “Adding Value Through the Innovations of Subsurface Utility Engineering (S.U.E.)” can be obtained from the Society of American Value Engineers website. Click here to obtain your copy.
SUE Articles
SUE FAQs (Click Question to reveal answer)
1. What is Subsurface Utility Engineering?
Subsurface Utility Engineering (SUE) is a branch of engineering practice that involves managing certain risks associated with utility mapping at appropriate quality levels, utility coordination, utility relocation design and coordination, utility condition assessment, communication of utility data to concerned parties, utility relocation cost estimates, implementation of utility accommodation policies, and utility design. [This definition is contained in: Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data, CI/ASCE 38-02, American Society of Civil Engineers, 2002.]
2. What major activities are involved in Subsurface Utility Engineering?
Major SUE activities are:
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Scope of Work – The process of developing a written project-specific work plan package that consists of scope of work, levels of service vs. risk allocation, project schedule and desired project delivery method. The SUE work plan package is agreed upon by the SUE provider and the client, describing the SUE work to be performed.
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Designating – The process of using a surface geophysical method or methods to interpret the presence of a subsurface utility and mark its approximate horizontal position on the ground surface or on above-ground surface markers.
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Locating – The process of exposing and recording the precise vertical and horizontal location and providing utility size and configuration of a utility.
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Data Management – The process of surveying, designating and locating information to project control and transferring it into the client’s CADD system, GIS files, or project plans.
- Conflict Analysis – The engineering process of using a conflict matrix to evaluate and compare depicted designating information with proposed plans (highway, bridge, drainage, and other) in order to inform all stakeholders of potential conflicts, potential resolutions and costs to cure.
3. How does SUE work?
SUE generally works as follows:
The project owner assumes responsibility for taking appropriate actions to consider and deal with utility risks. On small projects where few utilities are present, this may only involve making a conscious decision to proceed with the project using readily available information. On larger, more complex projects, the services of an engineer may be employed to provide expert advice and to use available technologies to provide better information.
The engineer, when involved, will advise the project owner of utility risks and recommend an appropriate quality level of utility data for a given project area at the appropriate time within the project planning and design process.
The project owner will then specify to the engineer the desired quality level of utility data.
The engineer will furnish the desired utility quality level to the project owner in accordance with the standard of care and will be responsible for negligent errors and/or omissions in the utility data for the certified utility quality level.
4. What are the benefits of using SUE?
SUE provides many benefits. Proper use of this cost-effective professional engineering service will eliminate many of the utility problems typically encountered on highway projects, including:
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Delays to projects caused by waiting for utility relocation work to be completed so construction can begin;
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Delays to projects caused by redesign when construction cannot follow the original design due to unexpected utility conflicts;
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Delays to contractors during construction caused by cutting, damaging, or discovering utility lines that were not known to be there;
- Claims by contractors for delays resulting from unexpected encounters with utilities; and
Deaths, injuries, property damage, and releases of product into the environment caused by cutting utility lines that were not known to be there.
5. Are there any standards of care for the use of Subsurface Utility Engineering?
The American Society of Civil Engineers (ASCE) has developed an important standard of care guideline, Standard Guideline for the Collection and Depiction of Existing Subsurface Utility Data, CI/ASCE 38-02. This standard guideline describes four quality levels of utility depiction:
- Quality Level D – Information derived from existing records or oral recollections.
- Quality Level C – Information obtained by surveying and plotting visible above-ground utility features and by using professional judgment in correlating this information to Quality Level D.
- Quality Level B – Information obtained through the application of appropriate surface geophysical methods to determine the existence and approximate horizontal position of subsurface utilities.
- Quality Level A – Precise horizontal and vertical location of utilities obtained by the actual exposure and subsequent measurement of subsurface utilities, usually at a specific point.
The CSA is currently developing a standard for the Mapping of Underground Utitity Infrastructure. It is expected to be completed in 2009 or 2010. The standard will reference the use of SUE and the ASCE 38-02 Quality Levels.
6. Where can copies of the ASCE standard guideline (ASCE 38-02) be obtained?
Copies of ASCE Standard 38-02 can be obtained from the ASCE Bookstore: http://www.pubs.asce.org or by calling 1-800-548-2723.
7. What qualifications should a provider of SUE services have to do the work properly?
Firms providing SUE services shall be licensed with the provincial engineering body for the provision of consulting engineering services (i.e. PEO, APEGGA)
It is recommended that project owners consider the following, not necessarily all-inclusive, criteria when selecting a SUE provider. Providers of SUE services should be able to:
- Demonstrate a thorough knowledge and understanding of designating, locating, and data management activities,
- Provide designating and locating services to the extent desired by the contracting agency,
- Survey SUE data acquired during the designating and locating phases to project control and transfer it into the contracting agency's CADD system, GIS files, or project plans.
Individuals assigned by the SUE provider to carry out the work should be well trained, experienced, and capable.
- Individuals in responsible charge of the work and responsible for certifying deliverables should be engineers employed by the SUE provider in accordance with provincial professional registration requirements.
- The project manager should have previously been involved in the management of one or more SUE contracts and must be available to commit sufficient time to the project.
Other team members should have previously been involved in SUE designating, locating, surveying, and/or mapping activities.
Resources of the provider should be adequate to carry out the SUE work in a timely manner, considering other possible commitments of work and the contracting agency's anticipated needs, including a possible need for work on several projects to take place simultaneously.
A wide range of equipment is necessary to detect the variety of underground utilities that may be present. Equipment available for utilization by the provider should include, but not be limited to, the following:
- ELF, VLF, LF electromagnetics, magnetometers, terrain conductivity meters, resonant sonics, and other geophysical designating equipment,
- Vacuum excavation or comparable nondestructive locating equipment,
- State-of-the-art surveying and data recording equipment, Software systems compatible with the contracting agency's CADD system.
Providers of SUE should have:
- The financial capacity to provide the required services,
- Measures of protection for the contracting agency against errors and omissions of data collection, interpretation, and management.
Providers of SUE services should be able to provide:
- Vertical data accurate to within ± 15 mm (0.05 ft),
- Horizontal data accurate to applicable survey standards.
Providers of SUE services should carry adequate insurance covering all aspects of the work. Minimum amounts should be in accordance with the contracting agency's requirements.
SUE Links
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