Location: Grand Rapids, Michigan
Product: Classic® 8
Manufacturer: Consumers Concrete - South Haven, Michigan
Design Engineer: Walltek - Clarkston, Michigan
Contractor: Walltek - Clarkston, Michigan
Total Area: 32,000 sq. ft. (2,973 sq. m), 42 ft. high (13m)
Case Study – Playground Expansion
Straight or Radius Split
Size: 8" H x 18" W x 12" D
200mm x 450mm x 300mm
Weight: 85 lbs., 39 kg
Design Challenge
To contain a 50' (15m) high slope which was historically
subject to soil erosion, an SRW was choosen
to maximize the land space at Knapp Forest
Elementary School in Grand Rapids, Michigan.
Zoning required that much of the donated land
remain untouched to protect a “green belt” between
the school property and public land.
Design Solution
Rockwood Retaining Walls’ Classic® 8 was the block
chosen for this formidable SRW project. Covering
one square foot per block, Classic® 8 was the most
sensible and efficient solution for the 32,000 sq. ft.
(2,973 sq. m) needed to surround the perimeter of
the school. The final design utilized a series of
tiered walls which met the “green belt” requirement
set forth by the zoning commission. Each tier
measures 7' (2m) in height and is spaced 5' (1.5m)
apart, as independent walls. At one section of the wall, the total wall height is an
impressive 42' (12.8m).
Soils on site were mostly sand, which made the actual removal of the native soil easy.
However, extensive excavation was required to accommodate grid layers that would extend
back approximately 40' (12.1m) behind the wall face, near the bottom of the wall. The
biggest concern was the global stability issue that would develop as a result of seven
multiple tiers being constructed on the project site. Careful consideration was given to
these individual walls, as there was no room for error. The multi-tiered walls would not
only retain the slope; they would also provide additional space for recreational play structures
at the foot of the wall. Public safety was a higher than normal concern, so the walls
were designed and engineered to exceed normal performance requirements.
The Result
Regarded as the biggest retaining wall in the Midwest, the Knapp Forest Elementary School
project demonstrates the performance of a Rockwood wall to retain a significant earth
formation, reclaim invaluable space, and ultimately prevent soil erosion.
