The Impact of Groundwater Lowering in Construction: A Complete Guide

Construction projects often face challenges related to working around groundwater. The presence of water underground can significantly impact the stability and effectiveness of various construction processes. To mitigate these challenges, engineers and construction professionals employ techniques to lower the groundwater levels. In this article, we will explore the process of groundwater lowering in construction and understand its implications for different types of projects.

Understanding Groundwater Lowering

Before delving into the effects of groundwater lowering in construction, it is crucial to understand the concept itself. Groundwater lowering refers to the systematic reduction of water levels in the ground during construction activities. This process is typically carried out to create a dry working environment, enabling the implementation of construction methods that require a stable foundation or the prevention of water seepage into excavations.

The goal of groundwater lowering is to lower the water table temporarily, ensuring a safe and efficient construction process. This technique allows construction professionals to work on projects that would otherwise be impossible in the presence of excessive or uncontrolled groundwater.

Groundwater Lowering in Construction: A Practical Guide to Dewatering, Second Edition

by Natalia Borges Polesso(2nd Edition, Kindle Edition)

5 out of 5

Language	:	English
File size	:	60171 KB
Screen Reader	:	Supported
X-Ray	:	Enabled
Print length	:	673 pages
X-Ray for textbooks	:	Enabled

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The Effects of Groundwater on Construction

Groundwater can have various adverse effects on construction projects if not properly managed. These effects range from decreased soil stability to difficulties in excavations, concrete pours, and foundation constructions.

Soil Stability

High groundwater levels can significantly impact soil stability, leading to soil erosion, instability, and potential collapse of excavations. In saturated soils, the water-filled voids reduce the soil's ability to support structures, thus posing a serious challenge to construction projects.

Excavations

Water accumulation in excavations hampers the construction process, often requiring dewatering to maintain a dry working environment. Without proper groundwater lowering, excavations may require constant pumping or result in delays due to water seepage issues. These challenges can prove costly and time-consuming for construction projects.

Concrete Pouring

Excessive groundwater can dilute and weaken concrete, leading to quality issues and compromised structural integrity. Pumping concrete into unstable conditions can also cause segregation, resulting in an uneven and brittle foundation. By lowering the groundwater table, contractors can control these risks and ensure a solid foundation for their projects.

Foundation Construction

Foundations that are compromised by high groundwater levels can suffer from inadequate bearing capacity, settlement, or even floating. Such issues can jeopardize the structural stability of buildings and other structures. By managing groundwater levels, construction professionals can ensure foundations are constructed on stable and strong ground conditions.

Techniques for Groundwater Lowering

Several techniques are commonly employed to lower groundwater levels during construction:

Dewatering Wells

Dewatering wells, also known as deep wells or relief wells, are installed to remove groundwater from construction sites. These wells extract water by creating a temporary deep hole and often employ pumps to control the water flow. Dewatering wells are effective for large-scale projects and situations where significant water reduction is required.

Wellpoints

Wellpoints consist of small-diameter pipes, typically 38 to 50 millimeters in diameter, that are installed around the perimeter of the construction area. These wellpoints are connected to a vacuum or pump system that draws out groundwater from the surrounding soil. Wellpoints are commonly used for shallow groundwater lowering and are highly effective in cohesive soils.

Deep Soil Mixing

Deep soil mixing is a technique that involves combining the in-situ soil with a stabilizing agent to strengthen and seal the ground. This process reduces groundwater infiltration, providing a stable working environment. Although primarily used for ground improvement, deep soil mixing indirectly contributes to lowering the overall groundwater level.

The Benefits of Groundwater Lowering

While groundwater lowering techniques add complexity and cost to construction projects, they offer numerous benefits:

Increased Stability

By reducing groundwater levels, the stability of the soil improves significantly. This enhanced stability allows for safer construction processes, minimizes the risk of failures, and ensures the longevity of structures.

Enhanced Productivity

A dry working environment allows construction professionals to work efficiently and effectively. By lowering the water table, projects can progress smoothly without interruptions caused by water-related issues.

Cost Savings

Though groundwater lowering may incur additional expenses, its proper implementation can result in long-term cost savings. Construction delays, rework, and structural failures caused by uncontrolled groundwater can be far more expensive to rectify in the long run.

Groundwater lowering plays a crucial role in construction projects by addressing the challenges posed by excessive groundwater. By understanding the effects of uncontrolled water and employing appropriate techniques, construction professionals can create a safer, more stable, and efficient working environment. Despite the complexities involved, the benefits of groundwater lowering far outweigh the costs, making it an essential consideration for all construction projects.

Groundwater Lowering in Construction: A Practical Guide to Dewatering, Second Edition

by Natalia Borges Polesso(2nd Edition, Kindle Edition)

5 out of 5

Language	:	English
File size	:	60171 KB
Screen Reader	:	Supported
X-Ray	:	Enabled
Print length	:	673 pages
X-Ray for textbooks	:	Enabled

FREE

Linking theory and application in a way that is clear and understandable, Groundwater Lowering in Construction: A Practical Guide to Dewatering, Second Edition uses the authors’ extensive engineering experience to offer practical guidance on the planning, design, and implementation of groundwater control systems under real conditions.

Discover engineering methods that can help you improve working conditions, increase project viability, and reduce excavation costs.

In the decade since publication of this book’s first edition, groundwater lowering and dewatering activities have been increasingly integrated into the wider ground engineering schemes on major excavations to help provide stable and workable conditions for construction below groundwater level. Consequently, many engineering ventures now require a more in-depth assessment of potential environmental impacts of dewatering and groundwater control, and this book details the latest best practices to evaluate and address them.

Includes New Chapters Covering:

• Cutoff methods used for groundwater exclusion

• Issues associated with permanent or long-term groundwater control systems

• Groundwater control technologies used on contaminated sites

• Methods needed to understand, predict, and mitigate potential environmental impacts of groundwater control works

Updated to reflect the crucial technological and application advances shaping construction processes, this book contains valuable direction that can give you a true competitive advantage in the planning and execution of temporary and permanent dewatering works. The authors cover cutting-edge methods and key subjects, such as the history of dewatering, working on contaminated sites, site investigation techniques, and operation and maintenance issues, including health, safety, and legal aspects. Written for practising engineers and geologists as well as postgraduate engineering students, this updated manual on design and practice provides numerous case histories and extensive references to enhance understanding.