It’s not every day that a 70-year-old hotel on the Las Vegas Strip needs to be demolished.
But when one did, GPRS was there to ensure the project stayed on time, on budget, and safe.
GPRS Project Managers Armando Gonzalez and Arthur Formoso mapped the buried utilities and inspected underground sewer lines in and around the historic resort to mitigate the risk of damaging this infrastructure during demolition. They completed their work while the hotel was still operating, and provided accurate data that not only ensured a safe demolition but will also be provided to the contractor selected to build on the site in the future.
“It was important for us to find everything so they could start the demolition and get on the right track,” Formoso said. “They didn’t want any surprises.”
Gonzalez utilized ground penetrating radar (GPR) and electromagnetic (EM) locating to identify and map all buried utilities on the property.
GPR is a non-destructive detection and imaging technology utilized in the construction industry for locating items such as utility lines, underground storage tanks (USTs), and rebar underground or within concrete slabs. A GPR scanner emits a radio signal into the ground or a slab and detects the interactions between the signal and any subsurface elements. Those interactions are displayed in a GPR readout as a series of hyperbolas that vary in size and shape depending on the type of material located.
Professional utility locators like GPRS’ SIM-certified Project Managers are specially trained to interpret this data, so they can determine what was located and provide an estimated depth for the buried obstructions.
EM locating compliments GPR by detecting the electromagnetic signals radiating from metallic pipes and cables rather than the utilities themselves. These signals can be created by the locator’s transmitter applying current to the pipe, or from current flow in a live electrical cable. They can also result from a conductive pipe acting as an antenna and re-radiating signals from stray electrical fields (detected by the EM locator functioning in Power Mode) and communications transmissions (Radio Mode).
Signals are created by the current flowing from the transmitter, which travels along the conductor (line/cable/pipe) and back to the transmitter. The current typically uses a ground to complete the current. A ground stake is used to complete the circuit through the ground.
At the hotel in Las Vegas, Gonzalez’s utility locates provided 99.8% accurate data for the demolition contractor to use for their planning.
“They already had as-built plans, so they kind of had an idea where everything was at,” he explained. “Once we came out, they kind of compared our locates to the drawings they already had. There were things that we were able to explain to them, like ‘this is what this is here,’ and stuff like that…”
Because of its age and the numerous renovations and expansions that had occurred at the hotel over the decades, the buried utilities on the property were a tangled web of both active and abandoned utilities. By utilizing EM locating, Gonzalez was able to verify which buried utilities were in use and which were inactive.
“The fact that we did our due diligence, even with things that seemed like they were abandoned or that they weren’t looking for, that’s what helped them realize ‘OK, we hired the right people,’” he said.
Formoso utilized a remote-controlled sewer inspection rover and push-fed sewer scope to map and inspect the integrity of the hotel’s buried sewer pipes. Both the rover and scope were equipped with CCTV cameras and sondes: instrument probes that are detectable from the surface using EM locating and allow for the mapping of buried wastewater utilities.
Because of the extraordinary depth of some of the sewer lines, Formoso also equipped his rover with a Prototek DuraSonde Transmitter. Colloquially referred to as a ‘super sonde,’ this 10 ¼ inch-long, 8 KHz frequency transmitter is detectable in nonmetallic pipes buried up to 50 feet down into the earth. By comparison, the rover’s internal sonde can locate pipes up to 15 feet deep.
Formoso was able to provide the client with a NASSCO-certified inspection report detailing the condition of the sewer system and providing photo and video evidence of all identified defects.
“There was just a lot of hidden stuff and vaults that we identified,” he said. “We saw a lot of as-intended maps, but they just kind of said ‘there’s something around here,’ and it was something that we had to actually find on the VPI side.”
Gonzalez, who lives near the hotel, personally witnessed the demolition, which occurred at 3 a.m. and was accompanied by a drone show.
“Even though they were going to demolish everything, [the client and the property owner] didn’t want to come across something that they didn’t know was there during demolition,” Gonzalez said. “The plans that they might have had could have varied from what was there because they’d changed it two to three times since the property was open. So, presenting a good, clean map of the property that was as detailed as possible to then give to the next client, that was important.”
From skyscrapers to sewer lines, GPRS Intelligently Visualizes The Built World® to keep your projects on time, on budget, and safe.
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Frequently Asked Questions
Can ground penetrating radar locate PVC piping and other non-conductive utilities?
GPR scanning is exceptionally effective at locating all types of subsurface materials. There are times when PVC pipes do not provide an adequate signal to ground penetrating radar equipment and can’t be properly located by traditional methods. However, GPRS Project Managers are expertly trained at multiple methods of utility locating.
Will I need to mark out the utilities that GPRS locates?
No, GPRS will locate and mark all utilities for you. We have a variety of tools and markers we can use to highlight the locations of utilities, underground storage tanks and whatever else may be hiding.
What deliverables does GPRS offer when conducting a video pipe inspection (VPI)?
GPRS is proud to offer WinCan reporting to our Video Pipe Inspection clients. Maintaining sewers starts with understanding sewer condition, and WinCan allows GPRS Project Managers to collect detailed, NASSCO-compliant inspection data. GPRS Project Managers not only inspect the interior condition of sewer pipes, laterals, and manholes – they can also provide a map of their location. The GPRS Mapping & Modeling Department can provide detailed GPS overlays and CAD files. Our detailed WinCan/NASSCO reports contain screenshots of the interior condition of the pipe segments that we inspect, as well as a video file for further evaluation, documentation, and/or reference.
