Making Dam Sure: How Safe Are Indiana’s Dams, Including Geist?
It is arguably the most important man-made structure in northeast Marion County. Standing 799 inches tall, the Geist Reservoir dam is impressive in scope, and yet people pass by it daily without giving the dam much thought. It’s there and the water stays where it’s supposed to.If, however, the structural integrity of Geist dam were ever seriously compromised, the result could be catastrophic. It pushes the limit of understatement to say that thousands of people, homes and businesses rely on a safe, structurally sound Geist dam.
Earlier this year, a highly critical report was issued by a blue-ribbon engineering association about America’s decades-old infrastructure – including the condition of its dams. The 2013 Report Card for America’s Infrastructure provided a sobering judgment of Indiana’s roads, bridges, dams, wastewater treatment facilities and the like. Using the familiar letter-grade system to rank the quality of each state’s infrastructure, the American Society of Civil Engineers (ASCE) slapped Indiana with a grade of D, based on physical conditions and needed fiscal investments for improvement.
Hoosier dams earned the lowest of Indiana’s marks, managing only a D-. Citing Indiana data, ASCE reported that more than 50 percent of the 1,088 dams regulated by the state needed remediation, adding that, “today many dams in Indiana are deficient as a result of age, deterioration, and a lack of maintenance.” The report also noted that many of the state’s dams were built 30 or 40 years ago.
The report’s troubling data prompted Townepost (publisher of atGeist and atFishers magazines) to seek a status report on the Geist dam. This is what we learned.
Construction on the earthen and concrete Geist dam was completed in 1943 – 70 years ago. “We would describe the Geist Reservoir dam as being in very good condition,” said Ed Malone, director of production, Citizens Energy Group, when questioned about the dam’s structural integrity. “We have no concerns related to its age. We inspect to evaluate the conditions associated with the dam, and any predictive or preventive maintenance needed.”
Geist Reservoir and the dam are privately owned assets of Citizens Energy Group (CEG). The dam is subject to regulatory oversight by the Indiana Department of Natural Resources (DNR), and carries a federal designation as a high-hazard dam, meaning a failure could cause loss of life, homes, buildings, utilities, etc.
High hazard dams in Indiana must be inspected every two years. CEG’s Malone noted that the Geist dam receives annual inspections by a third-party engineering firm. “Typically, there may be minor issues that are fixed immediately. The dam and spillway are monitored daily [by CEG], 365 days a year. Someone is there to physically inspect it, looking at both sides (of the structure),” he explained.
According to the DNR, in July of last year, Indianapolis engineering firm Cardno ATC conducted the required third-party inspection of the Geist dam, giving it an overall “fair” rating – the second-highest of five designations. “No existing dam safety concerns were recognized for normal loading [pressure] conditions,” explained Phil Bloom, DNR spokesman, who added, “Infrequent hydraulic or seismic events would probably result in dam safety deficiency” for structures with “fair” ratings. Bloom emphasized that the highest rating (“satisfactory”) is difficult to achieve, and to reach it, “The dam would have to have a safe performance under all conditions, including earthquakes,” he said.
When contacted by Townepost to discuss the Geist dam, Malone said a considerable amount of dollars are spent to ensure the longevity of each of the utility’s dams. “You’ll find we spend a considerable amount of time and effort… in assuring the reliability of this dam (Geist),” he emphasized.
In 2010, CEG made improvements to the dam’s upstream slope and crest (the water side). The work included pouring concrete over steel mats to mitigate erosion; raising the vertical wall on the face of the dam by two feet; replacing security fencing and installing security cameras; and driving metal sheets into the earthen dam to inhibit seepage. “Piezometers inside the dam are monitored on a monthly basis to ensure there’s no seepage,” explained Malone. A piezometer is an instrument for measuring the pressure of a fluid.
While there is every reason to believe the Geist dam is structurally sound, and that it is subjected to rigorous safety inspections and regular maintenance, one potential threat looms – an earthquake. The New Madrid Fault Line centered in southeast Missouri is capable of causing a significant earthquake with shock waves reaching Indiana. The New Madrid zone had four of the largest North American earthquakes in recorded history, and seismologists have long warned it is overdue for a seismic event of some consequence. New Madrid researchers say a violent shifting of its tectonic plates could potentially result in significant damage in seven states, including Indiana. The Wabash Valley fault system is also capable of wreaking seismic damage.
In 2008, a 5.4 magnitude earthquake centered in Illinois struck the Midwest, shaking buildings in Chicago and Indianapolis (source: US Geological Survey report.) DNR spokesman Bloom said, “Possible damage to Geist Dam from an earthquake would depend on conditions such as the magnitude of the earthquake, the geologic condition under the dam,” and other factors.
Liquefaction (shaking causing a severe loss of soil strength) is a risk associated with earthen dams. CEG‘s Malone said any such seismic activity impacting the Geist dam would be determined quickly. “We do have tremors periodically – two or three in the last ten years, very moderate. Also, we have cameras and can see any such seismic action because of water movement.” According to the DNR, the 2012 Geist inspection report concluded, “there is virtually no probability of liquefaction for the soil conditions at [the dam] under any reasonably anticipated ground-shaking.”
Perhaps most troubling is Indiana’s anemic commitment to dam safety: just $400,000 and only five full-time employees, which equates to 217.6 dams per engineer. In 2005, Indiana ranked 25th in full-time engineers devoted to dam safety. The DNR said it is taking steps to proactively address the issue. “You do the best you can with the tools you have. It’s for others to decide when additional funding is available,” said spokesman Bloom.
When asked specifically about the safety and inspection record of the Geist dam, DNR did not raise any red flags, and CEG called the dam’s condition very good. “It has been maintained, and continues to serve its purpose. We take that responsibility very seriously and are always vigilant about safety, stability and long-term reliability,” said Malone.
It’s worth contemplating, however, what might happen to the dam in the event of a serious earthquake – a force of nature that, as history has shown, is a legitimate threat in the Midwest.