Retaining Walls Create Space for University Expansion

THE CHALLENGE

Founded in 1898, Dallas Baptist University (DBU) sits atop the hills of Southwest Dallas overlooking Mountain Creek Lake. In 2007, the 5,000-student university embarked on a long-term plan to refurbish and expand the historic campus.

Redi-Rock has been part of DBU's campus improvement plan since 2007. Redi-Rock retaining walls also played a key role in this latest expansion and renovation project. For this phase of construction, DBU needed several unique solutions:

• A decorative and durable gravity retaining wall to protect the shoreline of its storm water detention pond
• A large reinforced retaining wall to create space for a new building
• A soil anchor wall with stairways to uphold an existing building and provide access to the new building

"The primary challenge was constructing a wall with very little space between buildings. The tight space meant there was a lack of room for traditional reinforcements," explained Ernie Fields, P.E. from the project engineering firm, Walter P. Moore.

THE SOLUTION

DBU initially chose Redi-Rock from local Redi-Rock manufacturer SI Precast because the block aesthetics fit the campus' overall long-term vision. But good looks are only part of the equation when it comes to retaining and freestanding walls.

Redi-Rock is an engineered retaining wall solution that relies on the weight of massive, one-ton blocks to literally hold back the earth. The blocks use a patented knob and groove system to create an extremely strong interlock between blocks. This allows tall gravity walls to be built in minimal space, which is a huge benefit on campuses like DBU's where space is at a premium. In addition, even taller gravity walls can be built using the incredibly efficient Redi-Rock reinforced system.

Redi-Rock gravity walls were perfect for the shoreline wall on campus

This most recent phase of construction required three separate retaining walls.

• For the stormwater detention pond wall on campus, the goal was to clean up the look and turn the detention pond into a focal point rather than an eyesore. Designers were able to create a 9 foot (2.7 meter) tall gravity wall with 9 inch (230 millimeter) setbacks to diffuse the wave action in the fairly large sized pond.

• To create more usable space for the new building to be built above the detention pond, designers took advantage of Redi-Rock reinforced walls. The tall, geogrid reinforced wall was finished with freestanding blocks to top off the aesthetics of the structure, framing the space for campus growth of the new building, parking lot, and road.

• The third wall, which was positioned behind the newly constructed building, was the most technically demanding. But, where there's a will there's a way with Redi-Rock. With site demands beyond the scope of a traditional gravity wall and not enough room for geogrid reinforcement between the existing building and the new building, Fields designed a soil anchor wall that could overcome the challenges. The 28in Redi-Rock blocks manufactured by SI Precast were cast with three galvanized loops through which rebar could pass. That rebar was tied to a rebar cage, which then incorporated the soil anchors and was poured full of concrete. The soil anchor grade beams were created directly behind the Redi-Rock blocks every couple of courses while a temporary wire wall held back the excavation. As if the site conditions didn't complicate construction enough, two elegant cast-in-place staircases came down the face of the wall to provide students and faculty easy access to both buildings on campus.

"It's gorgeous," said Greg Barrett, Sales Manager of SI Precast, of the finished project. "What made this project unique were the challenges posed by the site conditions and existing structures. This highlighted the versatility of Redi-Rock in a gravity shore protection wall, a tall reinforced wall, and a soil anchor wall."

Barrett also stressed that SI Precast worked closely with DBU to qualify the right installers for each of the walls on campus. With the scope of the project, the technical details, and the longstanding relationship with the university, SI Precast wanted to make sure they had the right crews bringing the vision into reality.

THE OUTCOME

Overall, DBU has used a mix of gravity, reinforced, and freestanding walls, along with columns and caps to complete over 50,000 square feet (4645 square meters) of walls on campus to date - with more to come! This phase of construction took approximately 4.5 months to complete.

The versatility of Redi-Rock allows for a consistent look on all the projects throughout the campus.

PROJECT DETAILS

Project: Dallas Baptist University Improvements #194 Engineer: Walter P. Moore Installer: Environmental Safety Services Inc. & Builder Services Co. Manufacturer: SI Precast Year Built: Multiple Years Location: Dallas, Texas