Taum Sauk Dam Upper Reservoir Rebuild


Lesterville, Missouri
Client: RIZZO Associates (Formerly known as Paul C. Rizzo Associates, Inc.)
Owner: Ameren Missouri

The Taum Sauk Upper Reservoir, located in Lesterville, Missouri, discharged an uncontrolled, rapid release of water when it failed. The Owner, Ameren Missouri, made the decision to rebuild the dam in the original footprint, using the materials from the existing dam along with natural pozzolan from a waste pond at a nearby coal-fired plant to create the aggregate for the new dam. The project consisted of excavation of the existing rockfill dike for crushing into RCC aggregates, foundation preparation, and mass leveling, dental, bedding and facing concrete, as well as the placement of approximately three million cubic yards of RCC.

Fall Line was retained by RIZZO Associates (Formerly known as Paul C. Rizzo Associates, Inc.) (RIZZO), the Engineer of Record and Construction Manager, to perform Phase 1 of the Mix Design Program for the Rebuild of the failed dam. Fall Line performed the laboratory testing on aggregates from the existing rim dike of Taum Sauk Dam. Aggregates were separated into individual sieve sizes after oversized aggregates were removed from the stockpile. Aggregates Qualification Testing was then performed to serve as a basis for the trial RCC mix designs.

Laboratory RCC mix designs with varying amount of fly ash and cement were put under the direction of RIZZO. Laboratory testing of test cylinders were then tested for compressive strength, modulus of elasticity, and split tensile strength. Accelerated test methods were also utilized to project the 365-day compressive strength, modulus of elasticity, and split tensile strength.

Fall Line performed soil cement testing for the reservoir floor plating of the newly constructed reservoir. Our staff provided a mix design program for the soil cement portion of the project. Testing included optimum moisture-density relationship, durability testing, and compressive strength testing of the cylinders made.

Once construction on the dam began, Fall Line created a 6,000 square foot testing laboratory that included a 2,000 square foot concrete cylinder curing room for utilization as the Quality Assurance testing facility at the project. The laboratory served as the on-site Mix Design Testing Facility, as well as Fall Line's headquarters for providing Testing Oversight, QA/QC for the project. No outside materials were brought in for the rebuild. The entire reservoir was completed with existing rock from the previous reservoir. The staff was comprised of over 30 engineers and technicians who worked around the clock to provide testing services for this Award Winning Project.