Jan 03, 2011

Home on the Riverfront

Combine a steep bank with a house on top and a river at the bottom, and preventing erosion from rain and flooding becomes a major priority. A home just outside of Louisville, Ky., on the Ohio River found itself faced with this challenge in late 2010.

Construction of the new house was underway when Eric M. Goodman of Form G was brought on site to design a bank stabilization solution. Initially, Goodman looked into using a small modular block system. He quickly realized, though, that the amount of excavation required to reinforce the walls would undermine the home’s foundation. Goodman turned to Redi-Rock , a precast concrete system that uses 1-ton blocks to create gravity solutions.

“With the Redi-Rock system, the excavation behind the walls was minimized down to 8 ft or so, and that saved a substantial amount of cost,” Goodman said. “We would not have been able to make the project feasible otherwise.”

Goodman was able to design a solution that required no reinforcement at all. The owners were impressed with the design and declared that Redi-Rock was the best solution for the project. They were given a choice in the aesthetics of the walls, available in three textures that give projects completely different looks: limestone, cobblestone or the new Ledgestone style.

“The owners picked Ledgestone based on color preference, the shape of the stone and the texture. The river banks have a sandy loam color, and the Ledgestone wall blends in and doesn’t look so massive,” Goodman said.

Ledgestone is said to give walls an incredibly natural finish. The organic patterns make individual blocks nearly indistinguishable in finished walls—even in large installations such as this one.

Form Follows Function

The project site is located within the conveyance zone of the Ohio River, so Goodman designed the walls to account for flooding as well. The walls were structurally designed with a curve to the upstream side so that water and debris would arc around the wall and reduce bearing capacity during a flood event. Rip-rap also was placed along the foundation of the lower wall to help minimize undermining.

In addition to stabilizing the slope, Goodman needed to create access to the beach. The grade change from the beach to the house measured 30 vertical ft, so hauling gear up and down the staircase for boating posed a major chore that the owners hoped to avoid. Creating a pathway that was accessible by motorized cart, therefore, became a priority to the homeowners. The design Goodman created followed the adage “form follows function.”

“We somehow needed to go from 1 to 1 to 3 to 1, and also incorporate a cart path,” Goodman said. “We decided on a cross-slope design with circular landings so the cart would have room to park. We designed the top freestanding wall using Redi-Scapes to maximize the view of the river and offer a gathering space along with a fire pit.”

The design called for two tiers of walls from local manufacturer Redi-Rock of Kentuckiana, with a Redi-Scapes freestanding wall on top. Redi-Scapes is a smaller block system ideal for garden walls and freestanding walls.

The wall construction on the river required four levels of permits, including permitting from the U.S. Army Corps of Engineers in order to build a structure of such magnitude on the shores of the Ohio River. When the permitting process was complete, the wall installation crew from Redi-Rock of Kentuckiana had 30 calendar days to install approximately 3,000 sq ft of retaining walls.

To create a foundation for the walls, the workers excavated a trench and installed dense grade aggregate. One block was buried to increase the walls’ structural stability. The Redi-Rock walls were simple to install using a small crew and a piece of heavy equipment. The blocks stacked in such a way that each interlocked with those above and below to create a solid structure.

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