Category Archives: Means & Methods

Each of us has at least one hilarious-yet-costly story about hitting an underground utility. The one I can contribute is from 1990 and lacks drama, so I mostly tell other people’s stories. Popping the water main in freezing Gillette, Wyoming on the Wednesday before Thanksgiving is a popular one. So is that one time the CPT rig successfully located the refinery’s hot crude feed. And I like to tell the one about the train that broke the gas pipeline and burned down the bridge  even though there’s no drill rig involved. The best stories feature spectacular property damage and a complete absence of injuries or fatalities. In reality though, many of these stories do involve injuries or fatalities. They happen, and we know about them, but we don’t tell them. Despite our lighthearted anecdotes, underground utility protection is serious business. Deadly serious.

A recently completed project for our oldest Pacific Northwest client got us thinking about current practices and developing trends in utility protection. Fewer incidents is everyone’s shared goal.  This post organizes some of our thinking about how engineers can protect critical underground infrastructure, and keep everyone safe on the job.

Call Before You Dig

We’re all familiar with 1-call notification requirements, the white-paint-and-a-phone-call exercise we all perform before drilling. Sometimes the engineer and the operator meet up at the site for a chat. But I’m surprised at how few engineers know that a Washington DC based group called the Common Ground Alliance is responsible for publishing the Best Practices Guidelines. In these Guidelines, a1-call notification program is a very small component, and there’s a lot more great guidance available. Common Ground’s current guide contains vast amounts of useful information for operators, engineers, and contractors.  The subtitle is “the definitive guide for underground safety and damage prevention,” and it’s not an exaggeration. I highly recommend that you browse through the other parts of the manual and pick some topics for your next staff meeting. Our topic will be Section 5.19, the Excavation Tolerance Zone.

The Gold Shovel Standard

The Gold Shovel Standard (GSS) is a related industry best practices group working to reduce line strikes.  GSS member firms adhere to the Common Ground Best Practices, so the groups overlap a little and have complementary objectives. Pacific Gas & Electric founded the group as part of their effort to reduce line strikes down from the high in 2011.  This presentation describes how they reduced dig-ins by 38% over less than 3 years.

Right now the GSS is recruiting municipalities to join the Association and start requiring excavation contractors to be Gold Shovel Standard members.  Sacramento embraced this practice and enjoyed immediate success. There’s no doubt in my mind that larger municipalities and State DoT’s will soon require GSS membership in their IDIQ geotechnical services contracts. It’s coming (and it’s a good idea anyway) so we might as well get out ahead of the issue if we can.

Developing Practices

The GSS’s most interesting initiative, to me, is standardizing incident reporting. Standardized data allows statistical analysis. Analyses reveal trends. And trends allows fact-based improvements to best practices. The work of collecting data, analyzing it, and improving practices defines the very kernel of engineering; it’s how the building code came to be and continues to evolve. The GSS is performing foundational work that will lead to standard methods that address utility protection in the same way that ASCE 7 addresses earthquake design.

The Portland Water Bureau’s Utility Protection Plan program may represent the future of excavation planning. It extends water main protection beyond line-strike avoidance to consider structural integrity.  For critical water mains the UPP program requires a math-based, drawn, reviewed, and approved plan for supporting the pipe in the excavation. No longer are we allowed to just open up the street, expose the main, and figure out a plan based on what we see. The UPP manual offers some excellent temporary support examples for a variety of crossing geometries. The Portland BWS has expert knowledge of water pipe vulnerability, and their move to require a detailed UPP’s is evidence that good support planning is critical to digging around buried lines.

Most of the Common Ground, GSS, and UPP practices are familiar to us from work around oil and gas pipelines. Pipeline operators, generally acting individually, have each developed practical risk-reduction standard procedures for working around their lines. Adopting these practices reduces risk, improves operational reliability, and saves money. Further, some of North America’s largest General Contractors self-impose extra requirements on their high-risk excavations.  These programs yield significant return on investment; they’re good ideas that smart operators embrace. We expect that in the next 3 years, especially as the GSS program gains traction, utility protection will have increasing importance to Atlas Geotechnical’s client base.

Drop us a note if your organization is thinking about adopting the Gold Shovel Standard, incorporating Utility Protection Plans in your internal excavation manual, or just generally interested in improving operations by making better plans.  We love these types of conversations.  

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It’s really not important what this is or what it does. The point is that every step of planning, design, and implementation happened in the correct order.

One of our projects achieved a significant milestone on Friday, exactly according to plan. Like most of our projects, it’s interesting construction at a unique site, and there’s no similar recent project to guide design and construction.

We learned recently that the shoring design failed to address a subtle but important detail. Once it was identified, though, it didn’t take long for the team to embrace the need for a rapidly field-engineered solution. Thankfully, strong relationships allowed us to add a ringer of a Structural Engineer to round out our already very strong team. They responded to our design requirements with an absolutely gorgeous 2-sheet drawing package in less than 3 days. We could not have met our deadline without their contribution.

Just because the work was installed before the deadline doesn’t mean that everything went smoothly. Atlas still have equipment stuck in Customs Purgatory at the Canadian border. I dearly hope to receive my 25 ton hydraulic ram back. Collaboration within the team, though, went flawlessly. The crew were able to source replacement equipment and keep us on schedule.

The point of this post is not that we made a pair of little gizmos and installed them in the nick of time, or that our clever little solution avoided a 6-month project delay. The takeaway from this project is that we achieved success using the exact same process that we use to succeed on huge projects. This one was just distilled down to a very compressed timeframe and had no schedule allowance for mis-steps. Every element of a big complicated design was executed on this small complicated one, just really fast and with intense coordination.

  • The project manager established clear lines of responsibility.
  • We wrote up a basis of design and stuck to it.
  • We established concise performance expectations.
  • We sourced locally available materials.
  • We identified a need for and hired specialty expertise.
  • The structural engineer adapted the design on the fly, and
  • The team assured quality.

The design and execution procedure was exactly identical to one used on a much larger project; we just moved through it in 5 days instead of five months or five years.

I feel grateful to be working with such a competent and diverse team on this large, visible, terrifically interesting project. Our project manager gave us about a week to recover, perform maintenance, etc, and then we tackle the next of the three remaining big problems. With the team we’ve assembled I have no doubt we’ll resolve them all with style and grace.

Seattle imposes a local requirement for verification testing of shoring tiebacks in addition to proof and performance testing. Because the required test load is 2.0 times the design load, and our design safety factor is 1.5, the test is almost certain to fail the anchor on the soil/grout interface.  At least, if our design achieves the target conservatism, the verification test ought to fail the soil/bond interface; otherwise our strength estimate is low and our design is pointlessly conservative.

One charming aspect of such high test loads is that verification anchors need additional strands in order to safely transfer the test load down to the bond zone. (We prefer to test a typical bond length with extra strands rather than use a typical strand count and shorten the bond length.) that means that the test anchors look really robust. The anchor below is only a 180-kip anchor, but it has 9 strands because it’s going to be tested to 360 kips.

Another fun aspect of testing sacrificial anchors is that they need to be installed in between soldier piles so they don’t take up the pocket for a production anchor. That means that we get to use a cool reaction frame for the test. Setting the frame is an extra step, but I think it makes the test setup look super old-school.

Really, though, the point of this post is just to share the photo that Wes sent down from the jobsite. The test results, to be honest, were disappointing.  The setup is really clean and efficient, though. We’ve already installed a similar anchor and then post-grouted it looking for higher capacity. I expect that later today we’ll have a similar photo of a great looking verification test and also proof of the high strength we used in our design.

It’s been an interesting week here at Atlas Geotechnical World Headquarters. Our project in Seattle is standing down while Equipment Operators Local 302, who struck last week, continue negotiating a fresh labor agreement with the Associated General Contractors. Three timezones to the left, our project supporting new friends WW Clyde Company in Hanapepe is shut down by Hurricane Lane.

The hurricane, and attendant drenching rains, are on my mind because this afternoon’s task is analyzing hydraulic rise caused by installing bulkhead walls that allow driving access out to the in-water bents. Crane loads during demolition and foundation drilling are legitimately heavy, and the site is crowded, so getting equipment into position has turned into a significant effort.

I include some snapshots from my visit to the site last week. The existing bridge is a graceful reminder of classic Corps of Engineers construction. Built in 1938 for the Territory of Hawaii government, it’s provided reliable service for more than 8 decades.  The replacement bridge will be higher, wider, and safer.  Plus it’ll be free of the weight restriction that is causing difficulties for the re-opened aggregate quarry just a couple of miles up the road.

The temporary bridge is already in place, courtesy of Hawaiian Dredging Company, though the connecting diversion embankments remain for WWC to install.  Our good friend Gary Coover at Pryzm Consulting has the lead on geometric roadway design and utility relocation onto the temporary bridge.  We’ll lend a hand with a very narrow MSE embankment design, but we’ve also got our hands full with crane access designs for demolition and construction.

One last note:  The pipe piles in the photo at right, which support the temporary bridge, were intended to drive 40 or 50 feet into the “compact mud-rock” stated on the 1937 boring logs (I do so love the very effective diction in older plansets). The existing bridge is supported on untreated timber piles 35 to 40 feet long.  Surprisingly, PDA testing during of the pipes showed very low capacity through that known bearing layer.  The pipe pile in the photo is 140 feet long, as long as the planned new bridge shafts. Work in the Islands is just filled with surprises.

Everyone stay safe through the storm, please, and we’ll pick up where we left off once the floodwaters recede.

A brief post this afternoon because it’s been a long day at Hilo Harbor. One of the most common questions people ask me about wharf construction is “how do you get the piles in the correct locations? It’s a good question, because you can’t really use a tape measure from shore, and the surveyor would have to wear water wings to mark the spot. The solution is a lot more work, but is the only way to accurately place the wharf piles in the correct spot: We build a falsework structure and place a template on it. And by measuring really carefully to be sure that the template is in place, we know that every pile that we drive through the template will be in the correct location too.

img_1187This photo has a pretty busy background, which is an unavoidable part of taking action shots of really big equipment in a crowded busy port, but if you look carefully you can see the 999 lowering a 40-ft long template that has positions for driving 20 wharf piles. The surveyor (in a red shirt under his PFD) is walking back to his equipment, which is set up over a very carefully marked spot on the template.  If that spot is in the correct location, then the template is correct. And if the template is correct, then we’re ready to drive piles with confidence. All of the rough-looking steel beans and pipe piles are temporary, and are only there to support the all-important template.

So, tomorrow, if all goes well, we start production piledriving that will continue for the next 6 months