Grout Performance Testing – Logan Martin Dam
Dam Remediation Using High and Low Mobility Pressure Grouting
Logan Martin Dam, owned and operated by Alabama Power Company, is a hydroelectric generation site located on the Coosa River in Vincent, Alabama. Since construction in the late 1960’s, ongoing remedial pressure grouting projects have targeted significant seepage flow reduction beneath the embankment dam which is founded on karst, a limestone geology characterized by underground aquifers, caverns, and the potential for sinkholes, particularly as seepage flow erodes the underlying limestone and continually changes its distribution. Alden and Alabama Power have partnered to design and construct a large scale enclosed pressure grouting test chamber (3’ wide by 3’ tall by 30’ long) and an associated test protocol to evaluate and optimize grout mix design performance in geo-materials that simulate the fractured, cavernous geology at Logan Martin Dam.
This first-of-a-kind test approach uses a small production scale grout plant to prepare and inject the high mobility grout mixtures into the test chamber. The test chamber is designed with discharge ports along its length to allow water initially occupying the test chamber—and subsequently grout—to be displaced as newly batched grout is injected. Throughout the grout injection process, pressure and temperature measurements within the test chamber, as well as discharge flow rate and discharge flow specific gravity measurements out of the test chamber, are used to monitor and evaluate grout dispersion characteristics within the chamber.
Grout injection criteria used to govern test advancement and later termination includes displaced grout quality (i.e., displaced grout specific gravity relative to that of the freshly batched grout) and the internal test chamber pressure. After grout injection, various performance metrics are evaluated to quantify mix effectiveness. The normalized grout take, for example, evaluates the overall mix efficiency by relating the injected grout volume to the volume available within the geo-material for grout to occupy.
Since conception, updates to the test facility and protocol have been made to facilitate low mobility grout testing, as well as grout performance testing in the presence of water cross flow. Results from this ongoing research program are being used to reduce grouting cost through grout mix design and bore hole spacing optimization, while also improving dam safety by increasing knowledge on how grout penetrates rock fractures without in-situ excavation.
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Between 1932 and 2010 the state of Louisiana has lost about 2006 square miles of land due to a combination of subsidence, sea level rise, and management of the Mississippi River. Computer models predict a further loss of 1800 to 4200 square miles in the next 50 years, amounting to 55% of the land in Plaquemines Parish and resulting in $300 million in annual economic damage. Following hurricanes Katrina and Rita, the Coastal Protection and Restoration Authority (CPRA) was formed as a single state entity with the authority to protect and restore the lands of coastal Louisiana.
The $50 billion coastal master plan includes restoration and risk reduction projects. The restoration projects include barrier island restoration, hydrologic restoration, marsh creation, ridge restoration, sediment diversion, and shoreline protection. The Barataria and Breton Basins have experienced some of the largest land loss—almost 700 square miles. Two sediment diversions are being designed, one for each basin. The sediment diversions connect the Mississippi River to the basins, allowing for the controlled diversion of up to 75,000 cfs of water and sediment to the Barataria basin and 30,000 cfs to the Breton basin.
The design and construction of sediment diversions on the scale proposed for Barataria and Breton is unprecedented, the results of which will rely heavily on the numeric and physical modeling required to design the major diversion features, including the inlet, conveyance, and outlet structures. Alden is constructing two 1:65-scale, live-bed physical models to test performance and effectiveness of the diversions.
Discover more:
- Making Mississippi Mud In Massachusetts To Restore Wetlands | Here & Now [wbur.org]
- A Mini Mississippi In Mass. May Help Save New Orleans From Rising Seas [90.9 Boston NPR]
- Rerouting the Mississippi River could build new land—and save a retreating coast [Science Magazine]
- Find the Mississippi River in Massachusetts [Chronicle 5 WCVB]
- To Save Louisiana’s Vanishing Coast, Build a Mini Mississippi Near Boston [The New York Times nytimes.com]
- Louisiana researchers tackle a changing Mississippi Delta [PBS News Hour Weekend pbs.org]
- Mid-Barataria Sediment Diversion could create, save 47 square miles of land over 50 years [nola.com]
- CPRA Using Giant Model to Test Mid-Barataria Diversion
- Mississippi River Diversions Could Save Louisiana's Drowning Coast [enr.com]
- Louisiana Coastal Protection and Restoration Authority [Official Website]
- A Mini-Diversion in Boston is Paving the Way for Louisiana’s Boldest Coastal Project [mississippiriverdelta.org]

Civil Infrastructure | Hydrology, Hydraulics, and Fluids
Mid-Barataria Sediment Diversion
Alden constructed two 1:65-scale, live-bed physical models to test performance and effectiveness of the proposed land rebuilding diversions on the Mississippi River.
The Cedar Cliff dam and hydropower project is located approximately six miles from Cullowhee, in Jackson Country, North Carolina. The dam and hydroelectric facility is owned by Duke Energy and is located downstream of three other hydroelectric projects that are operated as a system.
The primary spillway includes a Tainter gate and the existing auxiliary spillway system includes two fuse plug sections (with different crest/activation elevations). It was determined that the combination of the primary and auxiliary spillway systems were not adequate to safely pass the regulatory-increased Inflow Design Flood (IDF). The construction of a Hydroplus Fusegate system with six semi-labyrinth Fusegates in an enlarged auxiliary spillway channel was selected to increase spillway capacity to safely pass the new IDF which is now the full Probable Maximum Flood (PMF).
Two reduced scale physical models were constructed to determine the required size of a ventilation system for the proposed Cedar Cliff Fusegates and headpond and tailwater levels at each Fusegate for flows up to the sixth Fusegate activating. The tailwater levels were required for design of the Fusegate ballast system.
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Civil Infrastructure | Hydrology, Hydraulics, and Fluids
Cedar Cliff Spillway
Physical model study to determine hydraulic performance of a proposed auxiliary spillway system during flooding events