Location: Greencastle, IN
Size: 30,000 sq ft of retaining wall
Masonry Used: Used AB Classic Blocks - srw system from Allan Block
Submitted By: Allan Block
The project began as a private bid from selected firms. FA Wilhelm of Indianapolis, IN, was selected as the site construction manager/general contractor. The excavation and site package bid was then sent out in February 2013. The initial cost estimates with a competitive product were coming back higher than expected and so the local Allan Block producer, Reading Rock of Cincinnati, OH started receiving inquiries about supplying product for the project. Patience and determination paid off and they were permitted to construct an Allan Block Ashlar pattern wall mock up on site.
The look impressed DePauw University enough that it was allowed as an equal product for final wall bidding. Reading Rock, Decorative Paving, and Civil Design Solutions were able to come in with a better solution for the project at a lower cost due to the Allan Block unit design and ease of installation. In this case, Decorative Paving could install the Allan Block product faster providing a time saving advantage. Due to the student population, access to the site was regulated and monitored closely.
In addition there was an on-site inspector to ensure that construction followed the engineer’s specifications. Decorative Paving was the wall contractor and they proved their skill on this project. There was a lot of rain before they got started and the whole site was to be essentially a fill site so the wall was constructed with mostly structural fill. During construction of the multi-sport stadium, it was realized that there was a significant global stability concern with the site. Decorative Paving worked with the wall engineering firms to revise the plans and create an acceptable solution. The solution was a seven tiered terraced wall utilizing select backfill for the infill zones and extended geogrid layers to intercept the global stability slip arcs that were of concern.
The design challenge was that the geogrid layers could not extend beyond a line extending at a 1.75:1 slope away from the multi-use stadium structure footing for fear of undermining it during construction. This meant that a section of wall could not be built since the required cut would leave a slope of less than 1.75:1. The solution for that portion of the wall would be an in place concrete cut wall at the bottom of the toe that was designed as a cast footing roughly 4 ft-6 in. deep ( 1.4 m) and 2 ft. (0.6 m) wide.
This concrete cut wall would intercept the slip arcs that were of concern and ensure that the site remained stable while maintaining a solid construction slope. The whole project has been a collaborative effort between all parties from start to finish on this project. The resulting wall structures are a testament to how a closely managed project with a diligent contractor and a dedicated engineer can turn out. The clean lines and careful attention to detail have created a solid and functional structure that provides the high degree of aesthetics that DePauw University was looking for.