One of the projects that the grounds crew at Thuya has slated to address this spring is fixing the leak in the brook. As many of you may know, the brook is the man-made water feature behind the lower pavilion. The brook was created years ago as a water feature that flowed under the old boardwalk bridge.
The boardwalk allowed visitors to view the area behind the lower pavilion from above the often-boggy wooded area, on their way to the upper pavilion. Most of the boardwalk has since been removed, but the brook stayed and was rebuilt to look like an original and natural part of the landscape. During the subsequent rebuilds we made several little waterfalls into pools which produce a very pleasant and gentle babble. There are several stone seats around the brook, and a special surprise that delights many who discover it kneeling there. The grounds crew continues to add to the landscaping around the brook, to create a native feel behind the lower pavilion.
Water loss in water features is common. Water is lost through the natural process of evaporation and through evaporation as it splashes onto rocks or plants depending on its speed. Water can be wicked out of the feature from a partially submerged branch or plant stem or from the water being too close to the soil. The liner used to create the water feature can settle over time or slumps in the sides can occur. Cuts and tears can occur or the materials will simply age and deteriorate over time.
In the brook we discovered a few areas where the plant roots and the proximity to soil were causing some water loss through wicking or splashing. It was a good lesson to learn. We believe that the quality of the original rubber liner and its installation may have led to leaks which run the water level down daily. These discoveries coupled with the normal evaporation explain why the recirculating brook system does not hold water for long without needing to be refilled a few times a day, which is not ideal.
After a conversation between Thuya Garden Manager Rick LeDuc, Director of Farm and Gardens, Cassie Banning, and myself, we decided that the only way to fix the leak was to take the entire brook apart, put down a new liner, and rebuild the area. This project is the grounds crews’ top priority this spring. We plan to complete it before the garden opens on June 23.
We found an improved liner to install. It is 45mil (45/1000 of an inch) thick, and plant and animal safe. The crew will use one piece this time, instead of cutting and attaching the pieces together like we did the last time, which created more potential water loss. We will lay the new liner over the old one and fold it to create the right shape. This, along with the higher edges, should keep the brook water self-contained. We will continue to see some loss due to evaporation but under the shade of the trees this should be minor.
This project will be quite an undertaking because we used many large ledge-like pieces of pink granite to form the edges of the brook. The only way to move them is with our tripods and chain-hoists. The tripod we will use looks like the tripod people use to set a camera on. Our tripod has eight 12-foot long aluminum legs and steel hardware. Instead of setting a camera on top, we hook our chain-hoist underneath and lift between the splayed legs. The chain-hoist acts as a pulley that uses mechanical advantage to allow a single person to lift heavy objects, in our case large stones, vertically and lower them at the same consistent speed. It takes time and lots of patience to move these stones, which were selected and gathered specifically because of their age and weathering, along with their moss and lichens. The goal is to set the stones so they create the look of a natural brook flowing down a gentle slope.
I invite you to explore the brook area this season and let us know what you think.
Jason Ashur, Lead Groundskeeper at Thuya Gardens