Dams have been vital to human civilization for thousands of years, serving as critical structures for water management, irrigation, flood control, and hydroelectric power generation. From the ancient earthen barriers of Mesopotamia to today’s towering concrete giants, these engineering marvels have transformed landscapes and supported economic development. However, the increasing demands on water resources and the growing impacts of climate change can cause vulnerabilities in dams, making their integrity more crucial than ever.

As we navigate the complexities of maintaining and monitoring dams, effective leak detection emerges as a key component in ensuring their safety and longevity, safeguarding communities and ecosystems alike. While concrete dams often reveal leaks through visible cracks or seepage, earthen dams pose a more insidious threat. Their porous nature can diffuse the path of leaks, making them harder to pinpoint. These leaks can lead to a cascading effect, causing washouts that undermine the dam’s stability. As more soil is eroded, the leak worsens, creating a vicious cycle that can culminate in catastrophic failure.

Tailored Solutions for Dam Leaks

RETTEW’s geophysics team offers a solution. By employing advanced techniques, we can precisely locate leaks within earthen dams, enabling targeted repairs that minimize disruption to the surrounding infrastructure. Moreover, regular monitoring surveys act as early warning systems, allowing us to address potential issues before they escalate into critical emergencies.

The detection of leaks in earthen dams requires a tailored approach. The optimal geophysical technique depends on the specific site conditions and potential sources of interference. Electrical methods, while effective in many scenarios, can be hindered by the presence of steel sheet-pile cores, which disrupt the flow of electrical current.

However, a technique known as Spontaneous Potential (SP) offers a promising resolution. By mapping the electrical currents generated by subsurface water flow, SP can reveal active leak paths even in the presence of steel sheet piles. Additionally, microgravity surveys can identify areas of missing mass, indicative of soil washouts within the dam or beneath spillways. Ground penetrating radar (GPR), though limited by heavy reinforcement in concrete spillways, can also be a valuable tool in mapping shallow washouts.

By combining these techniques, RETTEW’s geophysics team can gain a comprehensive understanding of the extent and location of damage, enabling us to design and implement targeted repairs that restore the dam’s integrity and safeguard critical water resources.

RETTEW’s Comprehensive Approach to Dam Rehabilitation

RETTEW’s 30+ years of experience in dam leak surveys have equipped us to tackle a wide range of challenges. One such project involved an aging earthen dam exhibiting signs of distress, including seepage and a noticeable depression on its crest. While one governing body advocated for demolition and a complete rebuild, another sought a more cost-effective repair solution.

RETTEW’s task was to detect and map subsurface seepage pathways/washouts in the dam to aid in assessing its structural integrity and designing the extent of repairs.RETTEW undertook a comprehensive geophysical investigation, employing a combination of Spontaneous Potential (SP) and microgravity surveys. SP revealed streaming potentials related to active water pathways from the reservoir to seepage points, while microgravity identified areas of missing mass, suggesting potential washouts. However, the presence of dense reinforcement in the concrete spillway prevented the use of certain techniques, highlighting the need for a tailored approach.

The results of our investigation painted a clear picture. The dam’s southern end was particularly vulnerable to seepage, with evidence of both increased infiltration and subsurface erosion. These findings were corroborated by the microgravity data, which confirmed the existence of significant washouts.

Based on our analysis, RETTEW recommended exploratory borings and potential grouting of the anomalies. However, a severe storm triggered a timely emergency breach, which revealed the extent of the damage, ultimately necessitating a multi-year dam replacement project.

As the world faces increasing water scarcity and climate-related challenges, the preservation of earthen dams is more important than ever. Earth dams, often overshadowed by their concrete counterparts, play a crucial role in our water infrastructure. Yet, their porous nature makes them susceptible to hidden dangers. With our expertise and commitment, RETTEW is dedicated to protecting these vital structures and the communities that rely on them.