Landscape Contractor / Design Build Maintain

JUL 2016

LC/DBM provides landscape contractors with Educational, Imaginative and Practical information about their business, their employees, their machines and their projects.

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Hartford Mill Pond, part of Centennial Park in downtown Hart- ford, Wis., showcases how oversize retaining wall units offer an effec- tive solution for challenging site applications. The 10-acre pond was constructed during the early 1980s with a timber wall that had since deteriorated. The city wanted to replace the wood wall with a structur- ally sound solution that would be aesthetically pleasing, durable, and would allow them to construct a safe pedestrian walkway adjacent to the pond. Originally, Jason Schall, Hartford's city engineer, envisioned us- ing smaller riprap stones around the pond's perimeter. However, he specified oversize Rib Rock landscape units from County Materials because they provide economic and structural advantages. Measur- ing 2' x 4' x 2', the oversize blocks are much heavier (approximately 2,500 pounds each), resulting in a more stable structure to hold back the organic soil and water from the pond. Rib Rock units are engi- neered to retain earth securely. Plus, oversize units allowed the land- scape contractor for the project, Wondra Construction Inc., to install more square footage in less time. A larger block means fewer joints, which reduces water penetrating and freezing. As a result, ice damage is minimized, ensuring the wall will last that much longer. There were several site and engineering challenges involved with this project. First, the pond required draining before any of the old timbers could be removed. The dam valve was opened to reduce the water level and the remaining water was pumped out through a filtra- tion system to avoid dumping sediment downstream. As the team dug down to remove rotting timbers, they also discovered the subsoil was filled with decomposing organic matter, which is not suitable mate- rial for building a structurally sound wall. The crew had to dig down 12 feet to remove timbers and hit solid ground before they could start installing the foundation. Big Pond, Big Blocks By Bryan Jones, County Materials Above: The 10 acre Hartford Mill Pond in Hartford, Wis., had a timber retaining wall constructed around its perimeter in the 1980s. Thirty years of constant water exposure later, the wood was rotting and unstable. Jason Schall, the city engineer, with the help of landscape contractor Wondra Inc., which specializes in grading, erosion control and more, created a heavy stone retaining wall as a replacement for the unsightly and unsafe wooden beams. The city funded the project, which also included a path for pedestrians and bicyclists next to the pond. Left: The original intent was to use smaller stones around the pond's perimeter, but ultimately, the 2' x 4' x 2' Rib Rock units from County Materials were selected. The 2,500-pound blocks create a more stable structure to hold back soil and water. Another benefit of the large blocks is fewer joints for water to penetrate, which means less damage to the stones when the pond freezes in winter. 14 LC DBM Hardscapes (Continued on page 16)

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