By using 3D laser scanning techniques commonly used to determine floor flatness, Sportworks Field Design and The Motz Group were able to identify settlement patterns connected to old utilities and calculate the exact amount of stone required for remediation at Paul Brown Stadium in Cincinnati, long before the first strip of synthetic turf was removed. Additionally, the use of 3D scanning allowed Motz and Sportworks to deliver a precise analysis of the finished field after the synthetic turf was replaced.

“To our knowledge, this is a process that is not yet commonly used in the sports industry,” said Craig Honkomp of Sportworks Field Design. “3D laser scanning is both quick and inexpensive and is opening up a whole new set of tools to allow us more information before a project ever begins and more information after the fact to ensure it was done right. Our belief is more information means a more educated client, which allows for better decisions regarding where money should be spent.”

The project started when Bengals head groundskeeper Brett Tanner, CSFM, reached out to Honkomp following a presentation he had given at the STMA Conference last January in Ft. Worth. At the time, the Bengals were preparing to replace the synthetic turf at Paul Brown Stadium, and Tanner was concerned about several depressions in the surface; some were small “point” settlements of around a foot in diameter, while others were several yards in size. These undulations clearly had a negative effect on the planarity of the playing surface and were challenges for the grounds crew to maintain.

Knowing that the field had previously been natural grass, Tanner suspected some of the old utilities—including old irrigation heads, heating sensors and storm drainage—might have settled over time, but he didn’t have anything to back up his theory. A traditional survey, while useful, would never show all the undulations and smaller details necessary to make a connection between the unevenness of the field and whatever was causing it underneath. To compensate, Sportworks Field Design chose to use a method of measuring the field’s planarity by using 3D laser scanners.

The use of 3D laser scanners in architecture has become standard practice over time when extremely precise measurements are needed, and Sportworks Field Design’s sister company, Truescan3D, had scanned warehouse floors (a floor flatness analysis) on several occasions when a very precise grade was required. However Sportworks had never applied the technique to a field.

Using 3D laser scanners, Truescan3D was able to collect approximately 1.5 billion points of data regarding the planarity of the field, which they were then able to translate into a very precise map that showed all the dips and undulations.

Honkomp then compared the actual data to an ideal grade and was able to produce a heat map showing discrepancies. The heat map showed very few high spots, but several low spots, including places where the actual field differed from the ideal plan by up to several inches. Comparing the maps to old record drawings put into computer-aided design (CAD), Sportworks was able to identify patterns and suggest that settlement around the heating sensors may have been causing several of the problems.

When it finally came time to dig, the heating sensors were in the exact locations Sportworks had identified. The field had settled in those locations because the heating sensors had not been backfilled properly.

When combined with field drainage tests completed by Sportworks and subgrade soil tests, by geotechnical company Terracon, Sportworks was able to provide a comprehensive analysis to Tanner to allow him to make well educated decisions on where to spend money on remediation before making improvements to the field to prevent similar problems from happening in the future.

Tanner was able to look at utilities, soil, and drainage issues and make an educated decision to spend money remediating the backfill problems above the old utilities, and to fix existing drainage problems where the stone had locked up preventing water from getting through, but not to spend the money necessary to fix some of the deeper sub-grade soils. The work could also be completed in a compressed timeframe while the team was still using the field.

Additionally, because the measurements were so precise, Sportworks was able to provide The Motz Group exact calculations of how much stone would be needed to fix the issues so they could have precisely the number of cubic yards needed available.

Once Motz removed the old turf, and remediated the utility areas and the quadrant of the field not draining, they used laser grading to achieve precise grading for the new synthetic turf.

As a check on the process, Truescan3D re-scanned the field and Sportworks again compared the data to the ideal, helping to show the client that the new field was well within the normal tolerance of ¼ an inch and met the ASBA standard. Based on the data, Motz also adjusted some of the grades outside the sidelines before putting the new synthetic turf in place.

The field was scanned one final time after the turf was put in place to verify it still met guidelines.

Having used the tool so successfully at Paul Brown, Sportworks plans to use 3D laser scanning at many of the fields it is helping to design in the future, creating more exact field planarity, and a more consistent playing surface for the athletes.

Additionally, the scanning data allows for exact calculations of stone or other remediation material, preventing the client from having to purchase too little or too much.

Craig Honkomp, PE, PS, LEED AP, is with the Sportworks Field Design division of The Kleingers Group, www.kleingers.com.

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