UST (Underground Storage Tank Locating)
Underground storage tanks are never fun to discover. They are costly to maintain, cause potential pollution and contamination that can decrease land values and environmental hazards and when building or digging onsite with a UST, hitting one could be devastating to a project.
USTs were typically used for in home heating or industrial heating from the early 1900s to about the 1990s, if your house or property was build before 1950’s it is likely that a UST could exist on your property, we often encounter USTs on older properties between 1900-1970. Each state has UST information but that information is very limited and not at all complete.
What are Underground Storage Tanks? (UST)
Underground storage tank (UST) locating is the process of identifying and determining the precise location of buried or hidden underground storage tanks, which are commonly used to store substances such as petroleum, chemicals, or hazardous materials. UST locating is essential for various reasons, including compliance with environmental regulations, maintenance, leak detection, and preventing potential risks associated with buried tanks.
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Here's an overview of underground storage tank locating and its significance:
1. Regulatory Compliance:
● Many countries have strict regulations governing the installation, maintenance, and removal of USTs to prevent soil and groundwater contamination.
● UST owners and operators are often required to conduct routine inspections, monitoring, and leak detection to ensure compliance with environmental regulations.
2. Leak Detection and Prevention:
● Over time, USTs can deteriorate, leading to leaks that contaminate the surrounding soil and groundwater. Locating USTs helps detect potential leaks early and prevents environmental damage.
3. Site Assessment:
● Prior to construction or excavation activities, locating USTs is crucial to avoid accidental damage to tanks and associated pipelines, preventing leaks and environmental hazards.
4. Property Transactions:
● When properties change ownership, potential buyers or lenders may request UST locating to assess any environmental risks associated with buried tanks.
5. Methods for Underground Storage Tank Locating:
● Ground Penetrating Radar (GPR): GPR uses radar waves to detect underground objects, including USTs. It can identify variations in the subsurface caused by tank walls, fill material, and piping.
● Electromagnetic Induction: This method uses electromagnetic fields to detect the presence of metallic objects like USTs. It is effective for locating metallic tanks.
● Acoustic Methods: Acoustic techniques involve generating sound waves and listening for reflections to identify voids or tanks underground.
● Soil Probing and Drilling: In some cases, soil probes or drilling can be used to physically verify the presence of an UST.
6. Professional Services:
● UST locating is often carried out by specialized companies or professionals with expertise in geophysical methods, environmental regulations, and equipment operation.
7. Environmental Impact:
● Locating and managing USTs appropriately helps prevent soil and groundwater contamination, protecting both the environment and human health.
8. Documentation and Reporting:
● The results of UST locating are documented and reported, providing information about the UST's location, condition, and potential environmental risks.
9. Risk Mitigation:
● Proper UST locating allows for informed decision-making regarding tank removal, repair, or maintenance, reducing the potential for leaks and environmental damage.
In summary, underground storage tank locating is a crucial practice for environmental protection, regulatory compliance, and risk mitigation. It involves using various methods to accurately identify the presence and location of buried storage tanks, contributing to the safe management of potentially hazardous materials and preventing contamination of soil and groundwater.
UST (Underground Storage Tank Locating)
How is UST locating performed?
Locating underground storage tanks (USTs) involves a combination of techniques and methods to accurately identify the presence, location, and dimensions of buried tanks. Here's a step-by-step guide on how to locate underground storage tanks:
1. Determine the Need:
● Establish the reason for locating the UST. Is it for compliance with regulations, property development, maintenance, or risk assessment?
2. Gather Information:
● Obtain any available historical records, site plans, as-builts, or maps that may indicate the location of USTs. This information can provide valuable initial insights.
3. Choose the Method:
● Select appropriate methods for UST locating based on factors like soil conditions, tank material, and the level of accuracy required. Common methods include Ground Penetrating Radar (GPR), electromagnetic induction, acoustic methods, and soil probing.
4. Ground Penetrating Radar (GPR):
● Set up the GPR equipment and select the appropriate radar frequency.
● Slowly move the GPR equipment across the target area, collecting data profiles.
● Analyze the GPR data to identify anomalies, such as the reflection of tank walls or pipes.
● Identify the exterior walls and mark boundaries from edge to edge of tank.
● Complete cross sections of GPR scan to find depth of the top of the tank
5. Electromagnetic Induction:
● Use an electromagnetic induction device to emit electromagnetic fields into the ground. This can be used to locate fill lines, intake lines and lines to and from the tank.
● Monitor the response of the electromagnetic fields as they interact with metallic objects like USTs, and radiate the signal, to detect the metal of the tank and Mark areas where anomalies are detected.
6. Acoustic Methods:
● Generate sound waves (sonic or ultrasonic) and listen for reflections from buried objects or voids.
● Analyze the sound data to determine the presence of USTs.
7. Soil Probing and Drilling:
● Physically probe the soil using a soil probe or drill small exploratory holes in suspected locations.
● Carefully examine soil samples for signs of buried tanks or fill material associated with USTs.
8. Data Interpretation:
● Analyze the data collected from the chosen methods to identify consistent patterns or anomalies that indicate the presence of an UST.
9. Cross-Verification:
● If feasible, use multiple methods to cross-verify the results and increase confidence in the findings.
10. Mark the Location:
● Mark the ground with flags, paint, or other markers to indicate the locations where USTs are suspected.
11. Documentation and Reporting:
● Document the findings, methods used, and any other relevant information.
● Create a report detailing the UST locations, dimensions (if determined), and any additional observations.
12. Validation and Further Assessment:
● If necessary, perform additional assessment to verify the findings. This could involve excavation to physically expose the UST.
Remember that the accuracy of UST locating methods can vary based on factors such as soil conditions, tank material, and equipment quality. Accurate UST locating is crucial for regulatory compliance, environmental protection, and preventing risks associated with underground storage tanks.
UST (Underground Storage Tank Locating)
What can make locating USTs difficult to locate?
Locating underground storage tanks (USTs) can sometimes be challenging due to various factors that affect the accuracy and effectiveness of the locating methods. Here are some reasons why USTs might be difficult to locate:
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Lack of Documentation: If there are no accurate records, maps, or as-built drawings indicating the location of USTs, it becomes more challenging to narrow down potential search areas.
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Irregularities in Site History: Changes in land use, renovations, or previous tank removals that were not properly documented can complicate the process of identifying UST locations.
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Varying Soil Conditions: Different soil types have varying electromagnetic properties that can affect the penetration of radar waves or the response of electromagnetic induction methods, potentially leading to false readings or signal distortion.
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Tank Material: Tanks made of non-metallic materials, such as fiberglass or plastic, might not respond as readily to electromagnetic induction methods, making them more difficult to detect.
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Debris and Obstructions: The presence of debris, rocks, utilities, or other buried objects can obstruct signals and cause interference, making it challenging to accurately pinpoint USTs.
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Depth of Burial: Tanks buried at greater depths might not be detected by certain methods with limited penetration capabilities.
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Tank Shape and Orientation: Irregularly shaped or horizontally oriented tanks can result in weaker signal reflections or distorted readings, affecting the accuracy of detection.
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Signal Attenuation: The signals used in detection methods can weaken or attenuate as they pass through different materials, reducing their ability to reach or return from deeper USTs.
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Voids or Fill Material: If USTs have been removed and the voids left behind are backfilled with different materials, the signal responses can vary, leading to potential confusion in interpretation.
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Interference and Noise: Environmental factors such as electrical interference, radio signals, or nearby structures can introduce noise into the data and affect the clarity of detection. The more utility dense an area is the more experience it takes to detect a tank location.
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Limited Access: USTs located in areas with limited accessibility, such as under buildings, roads, or dense vegetation, can make it difficult to position equipment for effective scanning. Small areas can also pose a challenge to tank locating due to needing at least a 10x10ft space to use larger GPR units as GPR needs a 2ft space to begin to scan.
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Operator Expertise: The accuracy of detection methods relies on the knowledge and experience of the operator. Inexperienced operators might misinterpret signals or misjudge results. That's why our technicians have over 600 hours of training and locating USTs using a variety of locating methods.
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Cost and Equipment Limitations: More advanced detection methods might be costly, and not all facilities or professionals have access to specialized equipment.
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Combination of Factors: Often, the difficulty in locating USTs arises from a combination of these factors, requiring a thorough and systematic approach to overcome the challenges.
Given these challenges, it's important to consider a comprehensive approach that involves using multiple methods, cross-referencing findings, and seeking professional assistance when necessary. Here at AUUL, the goal is to increase the accuracy of UST location and ensure proper management, regulatory compliance, and environmental protection.
In combination with GPR locating, we also use specific magnetic locators that can detect USTs up to 8ft deep, allowing for a more accurate private utility locate.
