$45 million gone. Adios. That was the economic impact to Mexico for previous NFL matches.  Not only was the cancellation of the 2018 Rams v. Chiefs game a black eye for all parties involved, but also it resulted in an unprecedented joint “statement” from the NFL’s Commissioner Roger Goodell and Mexico’s President-Elect Andrés Manuel López Obrador.

Earlier this year, at the recommendation from the NFL’s consultants, Azteca Stadium brought in World Sports Solutions International (World Sports) to serve as technical advisors and make recommendations relating renovating the field.  World Sport’s resume includes, construction, renovation and/or maintenance of 9 of the 12 stadiums used during the 2014 World Cup – Brazil. 

Many in the sports turf industry watched the scene unfolding at Azteca Stadium in November 2018 in disbelief. There were many questions and not many answers. It’s human nature to try to blame a disaster on a single cause, the simpler the better. It would be wrong to point blame at a single cause. The reality is that decades of history, intense traffic, Mother Nature and technology all transpired to cancel the 2018 NFL Mexico City game.

Based on interviews with the grounds crew, reviews of reports and inspection of the playing field, World Sport’s agronomist, Renato Luis Lauretti, concluded that four factors all contributed to the field not being in playing condition: inadequate soil and drainage; installation of a hybrid system that hampered remediation efforts; weather; and high traffic.

Soil and drainage

When Azteca Stadium was built in 1968, the architects and engineers had a different understanding of sports fields than today. Fast forward to 2017 and 2018, and the Azteca soil had developed into almost entirely organic matter. Black, mucky soil that was easily compacted and easily became anaerobic when wet conditions persisted. This 40+-year-old soil, that by all accounts was the original soil when the stadium was first constructed, was of more interest to archeologist than sports turf managers.

To compound the problem, the drainage system that was originally installed when the stadium was built had been rendered ineffective over the years, filled with muck and of no practical impact. Water could not effectively penetrate the high organic matter soil and would remain trapped far above the drainage system.

While the field could look great, it simply could not handle any appreciable amounts of water and be playable. Moreover, once the rain fell the soil would become anaerobic, depriving the kikuyugrass of oxygen and adding unnecessary stress.

Technology

In the spring of 2018, the PlayMaster hybrid grass system from Tarkett Sports was installed at Azteca. The key advantage to hybrid systems is the added soil stability, which is lost over a short period of time once the warm-season grasses, such as bermudagrass and kikuyugrass, mature because the stolons and rhizomes provide the necessary horizontal reinforcement.

Azteca now had a PlayMaster, installed over easily compacted, high organic matter, mucky soil, with no effective drainage. The roots of the kikuyugrass faced a challenge, to stay above the carpet layer where ample oxygen was present or venture downward into compacted oxygen deprived environment to quickly wither and die.

The installation of the hybrid system created a major challenge for Azteca’s ground crew. To create the right environment for the roots to penetrate through the carpet layer into the subsoil, the subsoil needed to be decompacted and its composition changed by introducing sand to mitigate anaerobic conditions.

With the newly installed hybrid system, pulling cores was now off the table, as was the use of a deep rotary aerator. The PlayMaster became an impediment to fixing the underlying soil conditions that were allowed to exist prior to installation of the hybrid system. As a result, the hybrid system created a barrier to the implementation of cultural practices needed to promote a healthy sod by remediating the poor soil conditions and traffic events.

Weather

The summer and fall of 2018 was wetter than anticipated. The historical average rainfall over a 30-day period in Mexico City from June to September is between 4.4 inches to 6.3 inches per month. October sees about 2 inches and November sees about .50 inch. In 2018, October received more than its average amount of rain and 5 days before the game, November 14, the Stadium received close to .7 inches, bringing November’s total to over 1.1 inches.

With no effective drainage, the mucky soil stayed very wet contributing to the anaerobic conditions and the kikuyugrass remained in a weakened condition with its root system predominately above the hybrid carpet layers.

Traffic

The stadium is home to two professional soccer teams and the Mexican National team and hosts events almost every weekend. In 2018, Shakira played back-to-back concerts over the October 11 weekend, followed by multiple professional soccer games. The pitch was left in shambles after the Shakira concert, with dead and dying grass on a hybrid system installed over very poor soil that hampered cultural practices necessary to create a strong turf stand that could recover.

World Sports was brought in by Azteca Stadium to assess existing conditions and make recommendations in the capacity of technical consultants and eventual project managers if renovation was decided. World Sports’ agronomist Renato Luis Lauretti was brought in to oversee the project, supported by Breno Cuoto to oversee the sod farm and installation, and Fabio Camara, our engineer agronomist, to oversee the installation of the drainage system and sub base.

On March 20, 2019, the sod farm was far from ready. This singular challenge could spell disaster for the project. World Sports designed a fertility program and recommended immediate changes to the cultural practices designed to push the grass so that it could be harvested in early June. With roughly 2½ months, the grass would need to make dramatic progress to be harvested.

On May 10, 2019, World Sport performed its final inspection of the sod. Over the course of 50 days, the grass had formed a reasonably dense stand and was looking ready. The true test would be rolling a sod sample to visually inspect and understand the maturity of the root structure. Two test rolls were taken, with the conclusion being that the sod was still immature, but very close to being harvested.

After assessing the existing conditions and the likelihood that another failure was probable if the underlying soil conditions were not rectified, and based on World Sports’ recommendation that the sod would be ready by June, a decision was made by the Azteca Stadium ownership group to move forward with the renovation of the field by installing a working drainage system, replacing the high organic matter soil with 12 inches of sports sand (90/10% mix) and sodding the field using stadium’s existing kikuyugrass sod.

Once the green light for the project occurred, local contractors removed the hybrid system, irrigation and high organic matter soil. An attempt was made to locate and move the old drainage system, but it was deeper than anticipated and left in place to prevent delays to the project.

Fabio Camera arrived in Mexico City on May 31 to provide technical advice and oversee the installation of the sub base, drainage system, irrigation and soil base.  The local contractors and engineers worked quickly to maintain the tight schedule.

The sub base was graded with a 1-degree slope from the crown to the side of the pitch. The drainage system consists of 27 feeder drains on each side of the pitch that flow into a 6-inch collector drain on both sides of the field. The collector drains were previously installed by Azteca as part of a remediation effort earlier in the year. The feeder drains maintain the slope of the sub base and are supported with geotextile and gravel.

An irrigation system was installed, with new pump, clock and control using Toro elements, 24 heads with an extra valve and four heads at the south end due to its being a larger area.

The topsoil now consists of a 90/10 high quality sand to peat moss mix. The peat moss arrived a few days late, having traveled from Canada, which caused a 2-3 day delay. The slope from center to side of the field was reduced to .8%.

On June 11, the sod began to be installed; while the root systems could have been more mature, the initial rolls are all looking good and installation proceeded with few challenges.

At the time of this article, sod harvest and installation are proceeding. In the coming months we hope to update the STMA members on the results of sod installation and maintenance practices in preparation for the numerous soccer games and the eventual NFL game between the Chargers and Chiefs in November 2019.

Michael Newcomb is COO, World Sports Solutions International. World Sports Solutions International has offices is Brazil, California, Florida and Nevada, providing sports field construction, renovation, maintenance and consulting services for all levels.

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