Seeing eye-to-eye on inflow and infiltration challenges

This new column, contributed by Gordon Rose, P.E., and Janet Jackson, GISP, of McKim & Creed, explores various issues from the sometimes very different perspectives of GIS and civil engineering professionals. It will appear in CE News every other month and address water, wastewater, and stormwater infrastructure; site development; and other project-related topics. While Rose and Jackson may not see eye-to-eye on all engineering and GIS issues, they respect each other’s point of view and attempt to "intersect" their professions whenever possible.

In this first column, they face off on the following question: If GIS and Engineering see eye-to-eye, will it help your inflow and infiltration (I&I) challenges?
— Bob Drake, editor


Civil engineer’s perspective
Rose: Well, they had better see eye-to-eye or your challenges will be more than just I&I. If engineers see GIS as just a way to make a pretty map for the final report, then they are wasting their time. But why should we engineers use GIS at all?

First of all, data can reside within the GIS and, as engineers, we understand data. We live by data. We love data. Give me numbers and I am a happy guy! But many engineers, like me, are visual; we need a picture. And sometimes we can get lost in the data and not see the whole picture.

How many times have you had reams of data—in fact, so much data that you were drowning in it—yet still could not see where the problem was? Sometimes the data gives us tunnel vision; we focus on one or two bits of data, thinking the answer lies within that data. But that may cause us to miss other information that might just tie it all together. So how do we treat our myopia? How can we find out how these GIS geeks can help us? Can they literally draw us a picture using all this data that might help identify potential problem areas?

We were involved in a project recently where a municipal engineer told us he had a normal flow in his sewer system of 5 million gallons per day (mgd). However, after a 1-inch rainfall, he had a total flow of almost 20 mgd. Do you think he had an I&I problem?

Of course he did, but his real problem was identifying where it was so he could fix it. With a system of more than 200 miles of pipeline, finding the leak could have been like finding the proverbial needle in the haystack. But our GIS geek had built a database into the system maps. We overlaid the sewer system with the local hydrology and the GIS showed us that we had 36 manholes identified as "not found" in an area along a creek bed. Could it possibly be that they were so close to the creek that they were under water!? Bingo! "Hey boss, I think I found something here."

Sure enough, when we went back and looked more closely (in boats!), we discovered the missing manholes. Not only were many of them literally under water, some were even missing the ring and cover. Small wonder that the flow increased four-fold during rain events.

If we had looked solely at the data, we probably would have spent months searching for the problem area. We probably would have suggested that this engineer install flow meters in various pipe legs and spent months collecting (you guessed it) more data. Then we would have analyzed this data until we noted areas of higher flows after rainfalls and began zeroing in on the manholes along the creek bed. Eventually we would have found the problem, but we would have lost valuable time and money.

The picture we got from the GIS was invaluable. Very quickly, it pointed us to an area with obvious problems. We showed this to our client and he began fixing the situation immediately. Because he knew exactly where the problem was, the client was able to direct capital improvement funds not only to solve a pipeline problem, but also to create a solution that saved money in treatment costs.

So what have we learned? Sometimes our short-sightedness can prevent us from seeing the big picture. Perhaps we can use the expertise of other professionals to help us back away and see things we might have overlooked. We as engineers love technology and how it can help us perform our jobs. GIS is another tool in the toolbox that can help us perform our work, analyze our data, and help our clients.

Our client discovered that, by spending money upfront on developing a good system map, he was able to quickly realize financial benefits. Together, as GIS professionals and engineers, we were able to solve a problem for our client. And isn’t that why we are in business?

We haven’t solved all the problems, but we already have an early success. And we may have even helped some of our engineers believe in the value of GIS.

GIS perspective
Jackson: Wanting to see eye-to-eye and knowing how to do it are two different things. Being a team player takes more than just wanting it. First, think about which members are critical to your next project. If you have never or rarely included a GIS professional on your team, now is the perfect time to tap into that valuable resource, as GIS adds a new dimension to solving many problems. As you explain the project details and specific challenges, watch and listen to how each person answers the question, "How can my expertise help solve this problem?" A great project manager knows that when diverse professionals work together to solve a challenge, each will see the situation from a unique point of view. That is a good beginning. But don’t let it stop there, as the answer usually emerges from the possibilities (or synergy) offered by the team.

Hopefully, your GIS professional will not be able to keep quiet and will immediately begin explaining how GIS’s most powerful feature is the hidden database that resides behind the graphics—a major difference between GIS and CAD. When the GIS database is used as a central repository and holds data such as flow meter readings, pump station run times, sewer manhole repair and rehabilitation information, pipe age and materials, make/model, inverts, slopes, and distance, then you have the ability to begin the process of formulating a query, or question, and addressing your I&I challenge from the computer or GIS point of view.

The value of having all this data in one place is that the computer can analyze it by drilling down through the base mapping layers as well as specific utility information. When it finds exact criteria (pipe older than 10 years, located within 20 feet of a stream, that has been repaired twice in the last three years), the computer will spatially display what it finds on a map. Wham! Suddenly data you never thought went together creates a pattern or trend that is easily identified on a map.

Gordon says engineers love data. That’s something we have in common. GIS professionals love data also, but we love it when it’s spatially linked and organized into a database.

I have made solving the I&I challenge sound easy by using GIS, and for those with highly developed GIS systems, it might be just this easy. But most GIS databases are not built overnight. Spatially locating water and sewer features and then completing the database with all the valuable information (attributes) may take years. That’s OK. Start with a GIS master plan, be patient, make changes as needed, and watch your digital system grow. However, you don’t have to wait until it’s perfect to use it as a highly functional, practical tool for solving challenges and offering everyday solutions.

GIS can help manage I&I challenges, but it will also allow more efficient management of the entire utility division. Again, with GIS acting as a central hub of information, think of the possibilities when you link work order management, modeling, SCADA, and customer service records. When merged, these separate files take on a new life, which can make your life more efficient and manageable. No more waiting for someone to count the number of sewer manhole features in a specific sub-basin. No more hand coding which households are affected by the new stormwater regulations. No more determining which scenario of rerouting sewer lines will have the greatest positive impact. Your GIS will provide this information quickly, in an easy-to-view frame. It might even offer a few solutions to challenges that you hadn’t considered. The possibilities are endless when you use the hidden power of the GIS database to do some of your thinking and viewing.

The next time you are faced with a project that offers a difficult challenge, think about seeing eye-to-eye with a GIS professional. If you don’t know the powerful resource that GIS provides, just ask. But remember, GIS professionals can get pretty excited about sharing their expertise to a team that is ready to work together toward a creative solution. Helping others see the hidden benefits and viewing possibilities is what makes seeing eye-to-eye on I&I possible.

Gordon Rose, P.E., senior project manager at McKim & Creed, has 30 years experience in water distribution, wastewater collection and treatment, stormwater management, and planning. Janet Jackson, GISP, heads McKim & Creed’s GIS activities company-wide. Contact Rose and Jackson at McKim & Creed is an engineering, surveying, and planning firm with offices throughout the Southeast.

Posted in Uncategorized | January 29th, 2014 by

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