Sector – Botanical Gardens, Japanese Zen Waterfall
Location – Missouri
Application(s) – Ground Water Control, Chemical Grouting, Poly Urethane Grouting and Sealing


The east and west waterfalls in the Japanese Garden had developed cracks in the pools and were leaking large volumes of water. These waterfalls are typically in operation 9 months out of the year. The water that leaked through these cracks had eroded the subsurface of the pools and the surrounding earth around the exterior of the tiered pools of the waterfall. Large voids had developed under the pools and around the exterior.

Requirements & Challenges

Stop the water from leaking through the pools and eroding the waterfalls in a manner that would have the least impact on the footprint at each of the waterfalls.

The Japanese Garden, dedicated in 1977, was designed by the late Professor Koichi Kawana, a native of Japan and lecturer on environmental design and landscape architecture at the University of California, Los Angeles.

Rather than the typical garden filled with striking statuary, showy plants and flowers, the Japanese Garden is a monochromatic understatement, in which the viewer is permitted the thrill of personal interpretation and discovery. Such gardens, with a lake as their main feature, were popular among the Japanese feudal lords or daimyo of the 17th and 18th centuries. Because of the extensive lawn areas, they possess a feeling of openness unique to this style. The Japanese Garden also includes various garden styles that were developed by the Japanese in prior centuries.

Great care was taken with Seiwa-en (Garden of pure, clear harmony and peace) to ensure that the Garden would be traditionally authentic, incorporating in its design many concepts that make a garden more than greenery. The visitor to Seiwa-en will see distinct aspects of its beauty when viewing it from different vantage points. It is a world in microcosm, featuring carefully designed waterfalls, beaches and islands, sometimes with minimal plantings, as in the raked dry gravel gardens.

The small waterfalls suggest mountain cascades. The Blue Boulder Cascade, Seigan-no-taki, is constructed with three great steps symbolizing heaven, earth, and man. Cho-on-baku is the Waterfall of Tidal Sound. Water’s sounds are music in this environment.

Ideally, you would remove all of the rocks, boulders and cracked concrete and pour new concrete and reset all of the rocks and boulders. However, there are large boulders cast within the footprint of the waterfall pools and surrounding the waterfalls. The large rocks and boulders were handpicked and placed by the late Professor Koichi Kawana. Each of these large rocks and boulders are tagged and numbered. If one of these boulders were to be removed it would take a large crane to remove the boulder and then it would have to be placed back in the exact same spot. Some of these boulders have developed cracks over the years and there was a low probability that these boulders could be picked up without breaking. The equipment needed to do this would have been so large that the garden would have had to cut down some of the plants and trees just to gain access.


Helitech CCD came up with a plan that would be the least invasive with respect to the plant life and ecosystem within the garden. Helitech would install steel tubes called Manchettes and injection ports into the earth surrounding the pools of the waterfall and through the concrete base of the waterfall. Once these ports were installed, Helitech pumped a urethane grout into the ground to fill any subsurface voids and seal the pools from the underside. The urethane grout selected has excellent water sealing properties and is very elastic, so it can hold up to the freeze and thaw cycles that we experience in the Midwest.

Upon completion of pumping the urethane, Helitech removed the Manchettes and injection ports and then water tested the pools to make sure the pools were now holding water and the water was not leaking through the bottoms of the pools or around the pools and eroding the soil. Adjustments were made by pumping installing more ports and pumping more urethane.

The final step in the process was to seal the topside of the pools with a waterproofing membrane. The product selection for this application was involved due to the fact that the water that runs from these waterfalls into the lake impacts the ecosystem within the lake. There are Japanese Koi fish, turtles and other wildlife that thrive in this delicate ecosystem.

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