December 2022, Vol. 249, No. 12
Features
Using Regulation to Develop Natural Gas Systems
By Sam Miller, Vice President, Gas Engineering, Milhouse
(P&GJ) — Engineering design serves as a fundamental pillar of the lifecycle of an engineering project. The fundamentals of engineering design use industry standards combined with federal, state and municipal codes to produce a construction-ready engineering package.
Regulation plays a key role in determining the accuracy and reliability of the information provided on design drawings. For the natural gas industry, modern day regulation was founded as a response to a catastrophe.
On April 6, 1968, in the town of Richmond, Indiana, an existing cast iron natural gas main exploded near an existing sporting goods store, causing a secondary explosion from the gunpowder that was located inside the store. Both explosions killed 41 individuals and injured more than 150. The cause of the explosion was later identified as a corroding transmission pipe, which was owned by the Richmond Gas Corporation.[1]
In response to the explosion, the U.S. government passed the Natural Gas Pipeline Safety Act in 1968, which later went into effect in 1970.[2] As a response, the Office of Pipeline Safety (OPS) and the Office of Hazardous Materials Safety (OHMS) were created, which were eventually combined in 2004 into the Pipeline and Hazardous Materials Safety Administration (PHMSA).
For natural gas operators in the United States, PHMSA enforces federal regulations, including the Code of Federal Regulations (CFR) part 192, titled “Transportation of Natural and Other Gas by Pipeline: Minimum Federal Safety Standards.”[3] More than 305,000 miles (491,000 km) of interstate and intrastate transmission pipelines are regulated using CFR Part 192.[4]
While PHMSA provides regulations for all natural gas operators, many municipalities have relied on their own past experiences within their jurisdiction to create regulations. For example, the City of Chicago historically let contractors install natural gas utilities in the roadway via a trenchless method called directional boring.
When utilities are installed via directional boring, there is less visual confirmation of the location of underground utilities, causing an increased risk of a cross bore. A cross bore is the intersection of an existing underground utility or underground structure by a second utility installed using trenchless technology. This results in an intersection of the utilities, compromising the integrity of either or both utilities and underground structure.[5]
Over time, the City of Chicago saw an increase in the number of cross bores. As a response, they required all underground utilities to be placed in the roadway via open cut instead of directional bore.[6]
Regulations continue to evolve and, as shown by the examples above, are heavily influenced by historical events.
Critical Factors
Population Density
Federal codes provide the framework for minimum safety standards, and state and municipal codes use the specific geography and population density of their territory to further delve into the realities of installing natural gas pipelines underground within their jurisdiction. Population density specifically helps to determine the balance between natural gas distribution and transmission piping. As an example, the following are the three major natural gas operators in the state of Illinois: Ameren Illinois, Nicor Gas and Peoples Gas.
Amern is in southern and central Illinois, far away from major population centers such as Chicago. Because of low population density, Ameren’s system is heavily geared toward larger transmission mains that have to travel longer distances to service fewer customers.
Nicor Gas’s service territory primarily consists of the suburbs of Chicago, where population density is higher but does not include the City of Chicago. Nicor Gas’s pipeline network is a more balanced mixture of distribution main and transmission main.
Peoples Gas, the natural gas operator for the City of Chicago, has a pipeline network of almost solely distribution main, with transmission trunk lines interspersed within their territory.
Natural gas operators also have to consider how population density affects the density of other utility infrastructure in the area. In additional to natural gas, common utilities across the United States include water, storm sewer, sanitary sewer, electrical power and telecom/fiber. All these utilities have overlapping networks of above- and belowground infrastructure that must be maintained and improved upon to provide reliable and safe infrastructure to all people across the United States.
Accuracy of Information
Before the 1980s, installing underground facilities relied on contractors to make decisions in the field to avoid utility conflicts. The only method available at the time was simply digging to expose any existing utility. However, because of an abundance of inaccurate records, attempts were made to excavate many utilities only to find that they were not in the aforementioned location. As time went on, regulators determined that this caused too many utility conflicts, utility relocations and project delays. In the late 1980s, the Virginia Department of Transportation adopted SUE (Subsurface Utility Engineering) standards, originally known as “digging and locating” for all underground work located in their territory.
In the 1990s SUE began to be used more often, with the Federal Highway Administration (FHWA) actively promoting the SUE concept, as well as introducing the SUE quality levels we see today. SUE levels are broken out from A to D depending on the quality of information provided.
According to FHWA, SUE levels are defined as follows:
As SUE levels increase from D to A, the cost of providing each level of information increases. Depending on project specific requirements, many different SUE levels can be used. Utility density also plays a role in determining SUE levels for a project. For example, municipalities located in rural areas may rely more on SUE Level D as a more cost-effective option compared to other SUE levels. A major city such as Chicago can require a SUE Level C or higher because of the higher congestion of utilities. There are many different variables when determining SUE levels and, as such, each project should be considered on a case-by-case basis.[7]
Even before SUE levels were established, obtaining and maintaining records of locations of existing natural gas facilities has been a crucial factor to avoid conflicts. For natural gas operators, according to CFR Part 192.1015, all natural gas operators must have and maintain a Distribution Integrity Management Program (DIMP).[8]
While natural gas operators have DIMP programs that provide reliable information, there are fewer regulated utilities for which records can vary in quality, reliability and accuracy. Nicor Gas’s territory contains approximately 640 different municipalities.[9]
Depending on the location of the project or municipality, the level of information provided can vary. Even within a single jurisdiction such as the City of Chicago, the level of detail and accuracy of information can vary depending on the type of utility.
Utility Conflicts
According to PHMSA, excavation damage during construction activities is among the primary causes of pipeline damage. Only corrosion and equipment failure account for more incidents. Gas utilities experienced 85,896 leaks caused by excavation damage in 2016. While PHMSA can evaluate the effectiveness of states in enforcing their damage prevention laws, the specific requirements and the level of enforcement of those laws can vary considerably from state to state.[10]
Continuous maintenance and improvement of these utility networks require an immense amount of coordination, especially for areas with a high population density. In these areas, one critical factor of utility design is avoiding utility conflicts, especially in metropolitan areas with a high utility density. Most municipalities will require minimum horizontal and vertical separation requirements for each utility.
As shown in Figure 1, the City of Chicago has specific standards for horizontal and vertical clearance requirements for all utility installations. For Peoples Gas designs, all projects are required to retrieve existing utility information from the City of Chicago. Once the existing utility information has been obtained, a survey of the project area is completed to conform to SUE Level C. After both items have been shown on drawings, conflict analysis can occur, and the running line of the proposed gas main can be safely designed.
As shown in Figures 3 and 4, the level of information provided can vary drastically. Figure 3 shows a clear water main atlas page with specific right-of-way (ROW) dimensions and fittings such as valves, tees, elbows and hydrants. Figure 4 gives a general idea and scope of the location of the telecom utility but does not contain any dimensions or scale that ties the underground asset to a specific location in the field.
Using utility records provided in Figures 3 and 4 in combination with an aboveground survey would qualify as SUE Level C, even though both records provide drastically different levels of information. SUE Level C is only as accurate as the information provided on the records.
Chicago may be unique in the sense that there is one governing entity that manages utility coordination. Utility coordination in the surrounding suburbs, Nicor Gas’s territory, follows a different path. The amount and age of existing utility information available is completely dependent on the municipality, ranging from old physical records to modern GIS systems. As a result, the detail and amount of existing information shown on natural gas design plans can vary widely, which can put additional risk on operators and contractors during construction to properly locate and avoid utility conflicts.
Variation in Regulations
While there is little debate that regulations play a critical role in ensuring the safety of all natural gas pipeline operations, municipal regulations directly affect the cost of projects and programs. For example, as referenced in the “Natural Gas Regulations” section, the City of Chicago requires all natural gas pipe within its jurisdiction to be installed using the open cut method. According to the 2019 Rules and Regulations for Construction in the Public Way, all openings in the public way must also be restored according to Chicago Department of Transportation (CDOT) standards.[11] Figure 5 shows an example of the limits of restoration based off various openings within a sample roadway.
Figure 5 shows typical examples of how a simple street crossing with a natural gas pipe can impact restoration limits. First, if two openings are located within 150 feet (46 meters) of each other, the area between those openings must be restored. Second, if a new utility is being installed within 5 feet (1.5 meters) of an intersection, the intersection must be restored up to the flow line of the adjacent street.
Since natural gas pipes are required to be open cut in the roadway, these restoration standards must be followed. Experienced engineers working on natural gas designs in the City of Chicago understand these requirements and, in turn, use judgement to minimize restoration impacts. For example, if there are gas mains within 150 feet of each other, in many cases they will be moved farther apart to save on restoration costs.
In contrast to the City of Chicago, Will County, Illinois, has different regulations that also considerably impact the cost of natural gas design in its jurisdiction. According to the Will County Utility Permit Guidelines dated February 22, 2019, Will County does not allow roadway impacts for any newly installed facility without the written permission from Will County DOT.[12]
Natural gas facilities are required to be directionally bored across the roadway to minimize impacts to traffic and street restoration. Will County also does not allow the abandonment of underground facilities, requiring contractors to remove abandoned natural gas piping once it’s retired. The cost of the removal falls on the owner of the facility.[13]
Current Solutions
For engineering designs to be effective, information shown on design drawings needs to be reliable, accurate and easily accessible.
For the City of Chicago, the Office of Underground Coordination (OUC) is responsible for the protection of the surface and subsurface infrastructure from damage due to planned and programmed construction, installation and maintenance projects. Any proposed projects for new construction and installation work within the City must be processed through the OUC.
The OUC is made up of 27 reviewing utility members, consisting of both city agencies and private entities who review existing utility information and proposed projects to determine the effect that specific requests will have on their facilities.[3] The OUC acts as a centralized hub that disseminates existing utility information and provides coordination between its members to minimize conflicts in the field during construction.
The OUC process can be separated into two different stages: information retrieval (IR) and existing facility protection (EFP). During the IR process, each representative from the participating companies has 30 calendar days to respond to the proposed underground work.
Each reviewing utility member, consisting of but not limited to water, sewer, telecom, electric and natural gas utilities, provide information for the requested project area straight from their records. Combined with the City of Chicago’s requirement to survey all projects areas, this ensures that all submitted projects to the City adhere to SUE Level C standards.[7]
During the EFP process, each of the utility representatives will review the submitted project and, based off the proposed design and existing information shown, will authorize the permit, reject the plans due to a conflict or mark that their facilities are not located in the project area. Each utility reviewer will provide comments that need to be addressed until a permit can be authorized. These comments can help to address any concerns or questions that arise due to older or less accurate records.
Only once all participating members authorize the permit, then a project can be approved and issued for construction. Accurate and reliable information allows engineers to provide conflict analysis to mitigate risk of damage during construction.
While this whitepaper focuses on design, it is worth mentioning that design plans often require contractors to use their local 811 number before they dig to electronically locate any utilities in the project area. Electronic locates (SUE Level A) completed just before construction compiled with accurate information on the design drawings has shown to lower the risk of change orders and damage to other facilities.
Recent federal regulation also has been a driver for improved accuracy and reliability of information. CFR Part 192.607 reads, “Records established under this section documenting physical pipeline characteristics and attributes, including diameter, wall thickness, seam type, and grade (e.g., yield strength, ultimate tensile strength, or pressure rating for valves and flanges, etc.), must be maintained for the life of the pipeline and be traceable, verifiable, and complete.”[8]
While this regulation applies specifically to steel transmission natural gas pipeline, the key words are traceable, verifiable and complete. As technology continues to evolve, natural gas operators have already turned to GIS systems to help adapt to CFR 192.607. Natural gas operators were given 14 years starting July 1, 2020, to become compliant with CFR192.607. While it remains to be seen how GIS systems will evolve in 14 years, PHMSA’s goal is clear — provide regulation to improve the accuracy, reliability and availability of pipeline information.
Conclusion
Natural gas has become an integral part of everyday life in society. Federal and municipal regulations strive to provide safer, more reliable systems to minimize catastrophes. Design engineers play a critical role in providing safe designs to minimize field changes and risks.
It is critical for natural gas design engineers to understand where their information comes from and how it can be affected by current regulation. Engineering judgement is required to determine when existing information needs to be supplemented with advanced locating techniques. An understanding of federal and municipal regulations is crucial to maintain a balance between a cost-effective design and a safe design.
References
[1] Associated Press. 1968. “Two blocks of Indiana City leveled by blast, blaze.” Spokesman-Review. April 7, 1968. p. 1.
[2] Natural Gas Pipeline Safety Act of 1968. Accessed 2022. https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/Natural Gas Pipeline Safety Act of 1968.pdf.
[3] Chicago Department of Transportation. 2022. “Office of Underground Coordination.” Accessed 2022; https://www.chicago.gov/city/en/depts/cdot/provdrs/construction_information/svcs/office_of_undergroundcoordination.html.
[4] U.S. Energy Information Administration. 2008. “About U.S. Natural Gas Pipelines.” Accessed 2022. https://www.eia.gov/naturalgas/archive/analysis_publications/ngpipeline/index.html.
[5] PHMSA/NAPSR Plastic Pipe Ad Hoc Committee. 2014. “Meta - Analysis: Cross Bore Practices.” 2014.
[6] City of Chicago. 2022. “OUC Review Criteria.” Accessed 2022. https://www.chicago.gov/city/en/depts/cdot/supp_info/efp--projects_requiringreview.html.
[7] U.S. Department of Transportation Federal Highway Administration. 2018. “Subsurface Utility Engineering.” Accessed 2022. https://www.fhwa.dot.gov/programadmin/sueindex.cfm.
[8] Code of Federal Regulations. 2022. 49 CFR Part 192. “Transportation.” Accessed 2022. https://www.ecfr.gov/current/title-49/subtitle-B/chapter-I/subchapter-D/part-192?toc=1.
[9] Nicor Gas. 2022. “Our Service Area.” Accessed 2022. https://www.nicorgas.com/company/where-we-are/our-service-area.html.
[10] Hartman, K. and D. Shea. 2021. “How States Protect Pipelines from Excavation Damage.” National Conference of State Legislatures. Accessed 2021. https://www.ncsl.org/research/energy/how-states-protect-pipelines-from-excavation-damage.aspx#:~:text=Every%20state%20has%20its%20own,the%20part%20of%20the%20state..
[11] Chicago Department of Transportation. 2019. “CDOT Rules and Regulations for Construction in the Public Way.” Accessed January 2019. https://www.chicago.gov/content/dam/city/depts/cdot/Construction Guidelines/2019/2019_CDOT_Rules_and_Regs_101819.pdf.
[12] Will County Department of Transportation. 2022. “Utility Permit Guidelines.” Accessed February 22, 2022. https://www.willcountyillinois.com/County-Offices/Economic-Development/Division-of-Transportation/Permit-and-Access-Regulations/Utility-Permits/FileId/5980.
[13] Will County Department of Transportation. 2022. “Will County DOT Removal of Out of Service Utilities.” Accessed January 13, 2022. https://www.willcountyillinois.com/County-Offices/Economic-Development/Division-of-Transportation/Permit-and-Access-Regulations/Utility-Permits/FileId/48399.
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