This retaining wall project for Main Event Entertainment’s new family center in the Kansas City, Missouri area is an instructive example of a contractor altering the installation game plan by using science, critical thinking, and experience to overcome unexpected and potentially dangerous site conditions during installation. The walls have been successfully built and conform to engineering specifications.
The new, 50,000 sf center has a parking lot that required construction of two retaining walls. Keystone’s Regal Stone Pro® wall, a rear-lipped SRW, was selected for its durability and ease of installation. The smaller of the two was a fill wall that was needed to hold the live load of the parking lot. Installation was straightforward and accomplished without unexpected challenges.
Installing the second of the two walls was much more eventful. The issues that arose on-site revolved around a 20-inch main water line, the location of which was known but had not yet been confirmed by potholing (the practice of digging test holes to expose underground utilities and determine their horizontal and vertical location). It serviced the entire west side of the city of Independence. Wall installation was so close to line that not only was there a risk of cutting off the water supply to half the population, there was a danger to everyone on the job site that the waterline could fail and flood the area as a result of the construction activities.
The approach that was decided on was to start construction at the low point and install moving away from the waterline to keep the soil in place for stabilization. When this part was completed, the installer built the part of the wall going toward the line. As they neared it, the bank began to fail; they found they could only excavate 12 lineal feet at a time, just enough to put in the required geogrid, build the wall up and backfill to stabilize the bank and waterline.
Their method was working until at one point the bank collapsed and exposed 60 feet of the line. At this juncture, the installation team leader knew they had to leave in place what soils were left and move to the other end of the wall. They shot a laser on the last base course block that had been laid, made calculations, and began construction on the other end.
As the team worked toward the previous stopping point, they were paralleling the waterline and would frequently see sections of bank fail again and expose pipe, a sight that increased their anxiety over its condition. For an additional measure of security against the waterline damage, a brace was positioned on the water line as digging continued. They also positioned a spotter to watch critical areas of the operation.
At last they reached the point where they had left off earlier, and were able to make a perfect match to the previously laid base course, then build up the middle, stabilizing the bank and the waterline. All involved could now breathe a sigh of relief: the wall was installed and there were no unwanted waterworks to be had that day.
For this project, the Regal Stone Pro wall system was produced by Pavestone in Lees Summit, Missouri. Regal Stone Pro RockFace 3-Piece is an 8-inch (h) unit having a modern architectural design appeal with natural stone texture combined with softened edges. The three-piece system creates alternating scale and dimensions. Geoff Brown of Down to Earth Landscaping, Belton, Missouri, co-owns the company that installed the walls. He said, “We use Keystone products in the right applications because of their durability and ease of use. They outperform competitors in the consistency category and yet allow us to be cost-conscious.”