Managing system wide depth of cover to reduce risk to critical assets
Project Overview
- Develop new program for monitoring cover over buried pipe for entire pipeline system
- Steward site prioritization and mitigations
Project Impact
- Identified areas of low cover that increased risk for pipelines
- Raised land owner awareness in areas where land use has reduced cover over pipelines
- Significantly reduced cost of low cover mitigations through creative greenspace and other land owner agreements
- Reduced risk to critical infrastructure
According to PHMSA’s data, there were 182 product releases resulting from 196 documented line strikes between 2010 and 2021 in locations where the pipeline was buried 24” deep or less.1 Of these, 16 of the leaks were a result of farm activity in agricultural areas. (1)
Although the One Call system is effective for coordinating excavation activity with utility operators, 13 states have certain exemptions from One Call notifications when performing farming excavation. (2) While agricultural activities typically are not a risk to pipelines, soil ripping or tile installation can have much a deeper soil impact and present a higher risk. This is particularly true in farm fields where the pipeline may no longer be as deep as it was when it was first installed.
Current DOT regulations require pipelines to be installed at particular depths based on land use type (§195.248 and §192.327). However, there are over 125,000 miles of pipeline still in service (in the U.S) that were originally installed before to 1980. (3) Many of these older pipelines were installed prior to the existence of burial depth requirements and may also have lost some amount of cover since their installation. Cover loss can result from a variety of causes including natural erosion, farming practices, and changes in land use.
In 2016, a major Midwest liquid petroleum transportation services company came to HT Engineering with a mountain of data from recent pipe centerline surveys that also gathered pipe depth data. The operator hoped that the surveys might indicate areas where cover was less than adequate based on land use. Using input from local operations and damage prevention personnel, HTE developed a process for identifying, evaluating, and prioritizing low cover areas for risk mitigation.
Our team continues to manage the program activities including cost stewardship, monitoring and prioritizing locations of concern, and leading a multi-disciplinary team of operator and contractor personnel to ensure the safety of the pipeline system. This approach has resulted in increased public awareness in areas where historical pipe cover has been lost as well as creative solutions to depth of cover issues that have resulted in cost savings of up to 95% over traditional methods such as line lowering.
With the expertise HTE has gained developing and implementing this process from the ground up, we are eager to employ what we’ve learned to help the industry manage depth of cover concerns.
References:
- “Distribution, Transmission & Gathering, LNG, and Liquid Accident and Incident Data.” PHMSA, 20 Oct. 2021, https://www.phmsa.dot.gov/data-and-statistics/pipeline/distribution-transmission-gathering-lng-and-liquid-accident-and-incident-data.
- PHMSA, Washington, DC, 2014, Study on the Impact of Excavation Damage on Pipeline Safety, https://www.phmsa.dot.gov/sites/phmsa.dot.gov/files/docs/Report%20to%20Congress%20on%20Excavation%20Damage%20-%20October%202014.pdf. Accessed 26 Oct. 2021.
- “Gas Distribution, Gas Gathering, Gas Transmission, Hazardous Liquids, Liquefied Natural Gas (LNG), and Underground Natural Gas Storage (UNGS) Annual Report Data.” PHMSA, 20 Oct. 2021, https://www.phmsa.dot.gov/data-and-statistics/pipeline/gas-distribution-gas-gathering-gas-transmission-hazardous-liquids.
