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©2018 Enviroprobe Service, Inc. : 81 Marter Avenue : Mt. Laurel, NJ 08054 : 856.858.8584

Blog

March 2, 2015

It's a very common practice for environmental consultants to get soil samples around underground storage tanks (USTs). The selection of drilling locations depends on a lot of factors and sometimes it's preferable that they are located as close as possible to USTs without risking damaging them. Ground penetrating radar (GPR) is a great tool to use to delineate UST scopes due to its very high lateral resolutions.

GPR can be used to delineate scopes of USTs made of steel or fiberglass. Even if a concrete slab is constructed on the ground surface for the protection of UST, i...

February 15, 2015

Ground penetrating radar (GPR) has many applications. One of its applications in engineering is to delineate lateral extents of footings for bridges, buildings and other structures. Design and as-built plans are not always available when needed and a GPR survey could provide valuable information about the footings in a non-destructive and efficient way.

The GPR profile below shows a concrete footing with reinforcement. The top of the footing was about 3' underneath a concrete floor. The GPR profile was collected next to a steel supporting structure.

February 13, 2015

"The ground is snow covered, is it OK for the GPR survey?" This is a very common question from our clients. Ground penetrating radar (GPR) actually works well through snow or ice. Below is a GPR profile showing an underground storage tank (UST) with ground covered by about 4 to 6" of snow. The located UST was marked on-site as in the picture to the right.

Although snow or ice on the ground surface wouldn't block GPR signals, it's not a favorable working condition for some types of GPR surveys, such as those searching for underground utilities. A GPR designed for undergro...

January 23, 2015

One question we get frequently from our clients is: how accurate is underground utility locating? The alternate question is: what's the safe distance to drill or excavate away from marked underground utilities? Although there is no precise answer to this question, there are still some good practices to follow.

Some states require you keep certain distance away from marked underground utilities if powered tools are to be used. For example, in new jersey, you can only hand dig within two feet of a line marked by utility companies. In general, two feet is the minimal distan...

January 6, 2015

When there is a good penetration depth for ground penetrating radar (GPR), GPR can be used to estimate thicknesses of subsurface layers. However, caution has been taken as such estimation may not be accurate without references or ground truth information. 

As EM waves from GPR travel down and bounce back from a subsurface interface between two layers, the travel time can be determined. In order to calculate the depth to the interface, the wave travel velocity needs to be known. Although there are indirect ways to estimate the wave velocity and depths such as using the co...

November 14, 2013

We’re frequenctly requested by clients to bring “concrete GPR” to sites for searching something underground. However, sometimes these requests were based on the misconception of concrete GPR. Just because the medium is concrete it does not mean that the "concrete GPR” is the best approach.

The main difference between a concrete GPR and a regular GPR, such as those for underground utility locating and underground storage tank locating, is the antenna frequency. The antenna frequency of a concrete GPR system is usually in the range of GHz, while those of regular GPRs are t...

November 14, 2013

Enviroprobe conducted an underground utility locating survey at a gas station in Morristown, NJ. During the process of searching for underground utilities, an anomaly showed up in the ground penetrating radar data close to the pump island. The experienced Enviroprobe geophysicist immediately realized this could be an orphaned underground storage tank. Further investigation utilizing metal detectors confirmed the finding. The finding was notified to the client, a reputable environmental consulting company, so further appropriate actions could be taken.

November 5, 2013

Prior to drilling, digging, trenching, and excavating, it is essential to know where underground utility lines are located. It’s particularly important for gas stations. Unlike residential house and office building properties, gas stations usually contain extra underground utilities including those for gasoline/diesel tanks and pumping systems. Besides the usual utilities including electrical power, communication, sewer, water and natural gas lines, there are other important lines such as fuel/product lines, ventilation lines and electrical conduits for the gasoline/die...

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