Patoka Lake Seepage Remediation

Patoka Lake Dam is located 118 miles above the mouth of Patoka River, a tributary of the Wabash River in Indiana. The project is 13 miles northeast of Jasper, Indiana and approximately 55 air miles northwest of Louisville, Kentucky. The project consists of a 1500-foot long earth and rockfill dam embankment having a maximum height of 85 feet above streambed. The project have a 1500-foot long dike with a maximum height of 33 feet. The outlet works consist of a control tower with hydraulically operated lift gates, an 8-foot by 12-foot oblong conduit, and a 370-foot wide uncontrolled spillway in a topographic high between the main dam and dike. During original construction in the 1970's the foundation for the main dam was treated extensively with dental concrete to repair karstic features in the limestone foundation. The original design contained an extensive grout curtain from the right abutment of the dam extending through the spillway to the left abutment of the dike. During construction the grouting between the spillway and the left abutment of the dam was eliminated based on test grouting in vertical holes and the need to limit cost growth because of the extensive foundation treatment for the dam. In the spring of 1996, heavy rains resulted in pools 7 inches below spillway crest for extended periods of time. During the time the pool was in the spillway several sinkholes developed and were treated with sandbag rings. Sinkhole development was progressing in an upstream direction as time progressed. The potential existed to lose control of the pool through the sinkholes which were eroding the clay infilling in subterranean solution features in the limestone. In order to prevent the loss of pool, a foundation grouting program was developed for the area between the spillway and the left abutment of the dam. The grouting program used state of the art materials including a suite of additives to stabilize the cement grout and limit the bleed potential and pressure filtration properties. In addition, state of the art computer monitoring was used to control the grouting form a central location. Computer monitoring included real time onscreen displays of evolving grout pressure, grout flow rate, and permeability. The real time display was updated automatically about every two seconds. The Patoka Lake Seepage Remediation project was a revolutionary leap forward in the Corps' grouting practices through the first time use of balanced stabilized grouts and computer aided control and evaluation systems. The use of the new technology resulted in significant cost savings when compared to other traditional construction methods and far exceeded the performance criteria established for the project. The application of these technologies to grouting throughout the Corps of Engineers will amplify those benefits far beyond the benefits accrued at Patoka. 16 pp., 2 tables, 8 figures.