Inspection that took 5 months now completed in a single day
Pure Technologies completes longest single day pipeline inspection to date using PipeDiver® technology.
From the Colorado town of Buena Vista, the views of the distant Rocky Mountains are deceptively stunning. Up close, the terrain is hilly, inhospitable and extremely remote. With no roads and little access, this is helicopter, snowmobile and 4-wheel-drive country. As might be expected, the logistics of inspecting a water pipeline that runs through this unforgiving territory makes the inspection extremely time consuming and hazardous for everyone.
For the Homestake Water Project, the manned electromagnetic (EM) inspection that previously shut down the critical 44-mile (77 km) pipeline for at least one month annually over five years, was now completed in one day, thanks in part to an enhanced PipeDiver® EM tool developed by Pure Technologies.
From 5 months using tradition dewatering and manned entries to a single day. Now that’s progress.
“Amazing,” said Tom Hankins, Supervisor for Homestake Water Project, in describing the Otero pipeline inspection run. “With the PipeDiver tool travelling through the pipeline at three feet per second, we can do what we previously did in five months, [over a five-year period] in just one day…”
Colorado Springs and the City of Aurora are the second and third largest communities in the state of Colorado. The Homestake Water Project (Homestake) is a joint venture between the two cities to collect and transport water from the mountains to the communities that serve almost 1 million people.
The Homestake Water Project includes a collection system, a series of reservoirs, a tunnel that brings water through the continental divide and a pump station that delivers up to 120 million gallons of water per day through the pipe.
One of the pipelines managed by Homestake includes the 44-mile Otero Discharge Pipeline, a large diameter (66-inch) non-cylinder prestressed concrete pipeline (PCP) built in the early 60s by the Cities of Aurora and Colorado Springs. In the past several years, the pipeline has suffered a few major breaks and non-surfacing leaks. The critical pipeline, which provides 60 to 70 percent of Colorado Springs’ and Aurora’s water, is in a high-risk location, with few roads and steep inclines, and recently the pipeline has suffered catastrophic failures.
Variety of methods used to inspect the pipeline
Over the past ten years, Homestake has deployed a variety of methods to inspect the pipeline. This includes visual, above ground, manned electromagnetic cart, and inline leak detection using the SmartBall® platform, of which Homestake has been a licensee for more than six years. Homestake conducts their own SmartBall inspections, analysis and leak verification of the pipelines they manage.
Beginning ten years ago, over a five-year period, Homestake shut down the Otero Discharge Pipeline each September to perform a condition assessment on certain sections of the pipeline. The shutdown included two weeks just to drain the pipeline to prepare it for a manned electromagnetic (EM) inspection tool, and another two weeks to perform the inspection.
“This task is hazardous,” says Tom Hankins, “not just to the mobilization crews, but also to the inspection teams inside the pipe who required rope support on the steep slopes.”
Because Homestake enjoyed a good relationship with Pure Technologies and knew of its innovative inspection technologies, when Pure broached the subject of using an enhanced PipeDiver electromagnetic tool on the remote 44-mile Otero District pipeline, without the need for dewatering, Homestake became keenly interested. Especially as Pure Technologies was able to develop a new exciter for the PipeDiver tool, which could be used on non-cylinder PCP and deliver higher resolution data than in the past.
PipeDiver platform collects EM data and operates while pipeline remains in service
The PipeDiver platform is a versatile, free-swimming condition assessment tool that collects electromagnetic data on the prestressing wires, and operates while the pipeline remains in service. The tool has specialized electromagnetic sensors to identify and locate prestressing wire wraps, which are the main structural components of PCP and PCCP, and the primary indicators that the pipe will fail.
And so the planning began. The purpose of Homestake long distance PipeDiver inspection was to locate and quantify the amount of the prestressing wire wraps on all 44 miles in one run, identify the individual pipe sections with distress growth, and drive repair/replacement decisions. A long, tall order, indeed.
High-risk inspection not without its challenges
The proposed inspection was a technically challenging, high-risk project. The teams put more than six months of planning into the inspection logistics, and Pure Technologies worked closely with Homestake to ensure existing facilities could be used for the tool’s insertion and extraction. Homestake also facilitated a calibration with the new tool prior to inspection, which would help with wire break identification and quantification.
Safety a major issue propelling the inspection
In order to inspect the largest portion of the Otero Discharge Pipeline, the PipeDiver was inserted into a surge tower located 600 feet above the pipeline. This also required a rope crew and a fully-suited diver with an umbilical line to rappel via a sled 600 feet down the 66-inch pipe in order to align the PipeDiver in the proper direction. Once the tool was set in the right direction, the rope team safely hauled up the diver and cart.
The pumps were turned on, and the PipeDiver sailed off without a hitch.
“Safety is a major issue because of the rough terrain as the pipeline slices through the Rocky Mountains with lots of hills, highs and lows, which required lots of ropes to get in and out, with the crews experiencing slips and falls…this way the inspection is conducted inside pipe, which is much safer…it does a better job.”
Tom Vidmar, Superintendent of the Homestake Water Project
In addition, the mobilization team installed 55 tracking sensors along the 44-mile pipeline route to monitor the PipeDiver tool as it traversed the inhospitable and extremely remote pipeline alignment.
Recognized as longest single day PipeDiver tool run in the history of Pure Technologies
Contingency plans were developed in case the PipeDiver tool got hung up along the 44-mile route, but in the end, less than 24 hours later, the tool successfully sailed into the surge pond, to the applause of the Homestake and Pure crews. The PipeDiver tool was removed from the surge pond and the pipeline data retrieved.
In the end, the PipeDiver electromagnetic inspection, at 44 miles long, was recognized as longest single day run for the tool in the history of Pure Technologies. With Pure Technologies now analyzing the electromagnetic data, Homestake will soon have information on the location and amount of broken prestressing wires on all 44 miles of the pipeline, which in turn, will drive repair/replacement decisions for the proactive water authority.
All in all, not bad for a day’s work.