Finding the Leak

By Steve Bradley

Structural integrity is essential when you’re working with any type of building. But, as much we’d like for structures to last a lifetime, nothing can stay in pristine condition forever. Natural elements (water, wind, temperature) will inevitably deteriorate structures over time. It’s part of our role as structural engineers to mitigate this deterioration and to help in repairs when it occurs. For anyone who has spent time working with structural deterioration you know that water is often one of the most hazardous and sometimes the hardest thing is finding the leak.

Concrete deteriorated from contaminated waterWhile working on a project recently, my colleague and I observed salt contaminated water dripping onto and deteriorating a cast-in-place concrete pilaster. Chloride ion testing indicated contamination of up to 60,000 parts per million, which in terms of contamination means it was like a salt popsicle. This leak was jeopardizing the structure of the building, so we had to figure out where the water was entering and find a way to stop it.

Finding the source of the contaminated water was easier said than done. We determined the leak had to be coming in through an interstitial crawl space, fed though joints in a precast parking deck above. We were able to access the crawlspace by using our arms and legs to shimmy below a precast beam that provided just a few inches of clearance. I quickly realized that I was a little too wide and needed to get rid of a few layers if I was going to make it through the access slot. I divested myself of my primary coat and was able to get myself inside. I felt my way around with my hands, hoping there would be an obvious trail showing me where the leak was coming from, but it was as dry as a bone. I used my flashlight for further investigation into nooks and crannies, but it yielded no helpful results.

Mud observed in the crawl space after the warm upA couple days later, the leak still on my mind, we were back at the site with a better access to observe the pilaster. We thought we must have miscalculated where the origin of the leak was located as the crawlspace was dry. We put our heads together and once again concluded the source of the leak had to be the in the crawlspace. This meant we would once again climb down into the crawlspace. This time, once into the access point, we found exactly what I was looking for: moisture and mud! Meaning the source of the water and its path to the pilaster were now observable.

What was the difference between the two days? There was a 30° rise in temperature between our first and second visits and this heat wave had led to runoff causing the dry space to become wet space. With this knowledge, we could then prepare a plan to fix the leak.

Sometimes the hardest part of studying structural deterioration is determining how and where detrimental elements are impacting the structure. Where is the leak? Which parts are the most vulnerable? Frequently, the most obvious answer may not be the correct one, and you have to be vigilant and flexible in this field of work. Perseverance in the effort, as in life, often pays off in big ways.

Steve Bradley, PE
  My learning style indicates that my interest and attention aligns with generalities more so than specifics. However, it is not possible to be a successful structural engineer without paying appropriate attention to detail, so I have taught myself to do so. I have found understanding the general nature of a project as well as the minutia has helped me both design and communicate well throughout my career. As a creative person who has been trained in structural engineering I have an advantage in solving unique problems. With a wide-range of experience starting with bridges and heavy structures to green field buildings, building condition assessments and restorations, I have in-depth knowledge of how structures work. I enjoy feeling challenged on the job, so no project is too obscure, no problem is too complicated.

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