Dewatering: Considerations, Methods, Applications, and More

You’re probably aware of watering and how it works for plants and lawns. But when it comes to dewatering, most people have no idea whatsoever. In the context of dewatering, water is not just often used extraneously, but it can also be damaging. And this is where the efforts, strategies, and practices come into the fold to eliminate water when it is not required or where it may lead to damage.

Think of soil wet enough that the vegetation begins to drown that ultimately erodes the soil. Oftentimes, water finds its way through residential areas like basements. On the other hand, construction areas are also often flooded that can halt the site operations for an extended period. In these cases, it is imperative to get rid of unnecessary water that impacts the soil, commercial or residential space, and environment at the same time.

Continue to read to learn about dewatering fundamentals, basic considerations, methods, techniques, processes, and more.

What Exactly Is Dewatering?

In a traditional sense, dewatering is the process of displacing or getting rid of groundwater through a dedicated work site. For the most part, experts use evaporation and pump to start and finish a successful dewatering process.

Typically, experts perform this type of process prior to footing excavation. Performing dewatering also becomes crucial to lower the overall water table that might create issues for other excavations later on. You can view dewatering through the lens of solid control or water control.

What is the Main Purpose of Dewatering?

At its core, dewatering is a sequential and strategic process to drain groundwater or rainwater from one specific excavation. For instance, without performing this process, construction sites can start on-site operations. The dewatering process ultimately separates water from solid substances like dredged slurry and drilling mud.

When it comes to construction and industrial worksites, water accumulation in excavation and trenches is quite common. This water accumulation leads to downtime where work areas are inaccessible because of flooding.

In these cases, the dewatering process becomes integral to resume operations. Besides, dewatering offers added safety and security for the entire operational crew on the site. It makes perfect sense for industrial and commercial players to implement a dewatering process before excavation of a site. It is the most effective way to lower the water table of an area and avoid creating issues at the start of the excavation.

Accumulation of Water

There is more than one reason for constant water accumulation on different sites. Predominantly, rain is the main culprit of water accumulation with a high water table. When it comes to construction sites, accumulation of water can occur in trenches, excavations, high table water locations, and sloped areas.

Standard Dewatering Applications

Well-pointing

Well-pointing refers to the strategic placement of shallow wells around a specific area in order to collect and separate water.

Pit Dewatering

It involves mining excavation sites with multi-layered access points and ore pits that often accumulate water and need urgent water control or removal.

Rim Ditch

As the title suggests, this application involves multiple berms and ditches designed to force the slurry flow. As a result, each side of the berm gets the coarse elements and other elements accumulate water at the bottom of the ditch.

Bypass Flow

This application involves a diversion of an insufficient drainage pipe that no longer can deliver water to decrease the water collecting process.

Construction Dewatering

This application involves a basic groundwater removal process on the surface area of a construction site.

Open Ponds

This application involves collecting low-level and over-the-ground water areas with laden slurry and toxic materials.

What Else?

Well, even the installation of common utility lines like water, electricity, telephone, and sewers requires dewatering. On the flip side, dewatering also has a wide range of applications in the mining field. For example, dewatering plays an important role in borrow-pits and rock mines. The dewatering process also takes place in lake excavations in order to construct a solid stormwater management network.

Focus on Key Dewatering Considerations

Signs

One of the main considerations for dewatering is to check soil erosion signs that may pinpoint instability. The truth is that erosion or instability is a major issue in big construction projects. So, make sure to control the erosion to preserve the original condition of the site and safeguard the structure at the same time.

Land

The main consideration of dewatering is to assess the kind of land. Your first step should be to take a closer look at diverse soil properties and study the ground to determine the most suitable dewatering method you can apply.

Weather

Take into account the weather conditions how it might impact the excavation process. You should avoid dewatering during heavy rain that might accelerate the infiltration rate.

Method

It is imperative to select the most practical dewatering method or technique. Carefully review the respective site and take into account soil parameters and then see whether a specific dewatering method would be cost-effective and efficient to pump out or suck groundwater.

Pump

Like the dewatering method, it is also crucial to select an appropriate dewatering pump. Remember each dewatering pump comes with its own application. Whether it’s draining reservoirs or floodwater, make sure to choose the dewatering pump that matches your needs. Also, make sure your dewatering equipment is versatile, safe, errorless, and efficient.

Major Dewatering Methods

Depending on the groundwater condition and type of soil, let’s take a look at the main dewatering methods:

• Well Point-based System

The title for the easiest installation goes to a well-point system. Not to mention, it is also a highly flexible, practical, and cost-effective dewatering method. What’s more is that this type of method works under most hydrologic and soil conditions.

In a mechanical sense, this type of method involves drilling the wells around the main construction site and then placing them into the wells. A well-point system, at its core, is a combination of small-diameter and interconnected wells with header pipes that lead to the main suction pump.

In this method, you have to abstract groundwater through well-points, which generates a vacuum pump. Now, the pipe has a perforated ball valve that regulates the water flow from one end to another. Through this dewatering method, you can lower the groundwater to over six meters. This dewatering method is suitable for buildings with deep constructed basements and sand gravels.

• Open Sump-based Pumping

Open sum-based pumping is arguably the most reliable method of dewatering and caters to a variety of conditions. It is also the most cost-effective, practical, and straightforward dewatering method. A sump refers to an area of a hold in the ground where collect water is pumped out for disposal.

One of the prerequisite conditions of this method is that groundwater has to be deeper than the usual basement floor. Technically, sumps and drains are constructed with equal corners and sides along with the foundational pit. After that, the drain sucks the groundwater and transfers it into the main sump. From there, the water is constantly excavated with mechanical or manual help.

This type of dewatering method is suitable for rock and soil conditions. For instance, you can apply this method in hard fissured rock and high-scaled coarse soils. Depending on the scenario, make sure to take into account basic considerations before starting this dewatering method.

And that’s because this technique involves a minimal risk that can collapse both sides. For instance, when it comes to fine-grained soils like fine sands or silts, there is a high degree of risk that can make the entire foundation unstable and result in ground settlement and movements.

• Eductor System

The educator dewatering system or ejector dewatering system is a quintessential technique. Experts use this specialist method in soils with low permeability with clays and silts. In a typical sense, Eductor dewatering system is used to support and stabilize the soil and slope sides in the excavation area.

Contrary to misguided perception, educator dewatering system is not similar to a well-point dewatering system. In fact, Eductor dewatering system utilizes highly pressured water across all units. In this type of dewatering technique, supply pumps are located straight on the ground level in order to transfer high-pressurized water, whereas the ejector nozzle is at the center of the well. The water flow via the nozzle ultimately produces an automated vacuum within the well and gets rid of the groundwater.

• Construction-based Deep-Well

When there is a need for deep excavation with a large groundwater quantity that requires immediate removal, this is where the construction style deep-well dewatering method comes into play. You can apply this method by constructing large deep wells in rocks or soils with the permeability of high gravel or moderate sands.

Fundamentally, this type of dewatering method is capable to drain water over 24m of depth. However, the well’s capacity, deep spacing, and depth can vary from one site condition to another. In some cases, the deep-well dewatering method is not a practical choice and requires switching to educators.

Learn to Use Dewatering Bags

Dewatering bags are highly durable and made out of geotextile fabric. This fabric works like a water filter to get rid of sediments from the liquid. In fact, these types of dewatering bags are used on construction sites and dredging operations.

Geotextile fabrics are also used in areas where the water table is close to the shoreline or too high. In addition, the size of a dewatering bag has to be precise and in line with the pumping flow and sediment type. The trick to using dewatering bags is to avoid more than one pipe discharge that fails the filter bag.

The right course of action is to manage your water runoff and navigate it to the closest storm inlet. For the most part, dewatering bags come in large sizes with geotextile and natural filtered fabric to get rid of sediments and oils from the water.

What about Dewatering Pumps?

Dewatering applications have their own set of challenges like transferring liquid with abrasive and solid-laden materials. The good news is that there are various ways to pump out the water for specific applications. However, some applications to get rid of accumulated water are more effective than traditional ones.

Nonetheless, you can select a suitable method to pump out water for “your” dewatering application. But make sure the pump is designed to handle non-clogged and solid materials. For instance, one of the safest and most suitable choices is submersible pumps for complex dewatering applications.

In fact, these pumps are designed to withstand solid abrasive content and are not vulnerable to clogging. It means you can completely submerge these pumps into the water without issues. On the other hand, self-priming type of pumps is also suitable options for dewatering. These types of pumping solutions offer more perks than traditional-style pumps.

Take Proactive Measures

It is never too late or too early to take a practical stand and prevent water accumulation that may impact your commercial, residential, or industrial area. Oftentimes, experts use slurry walls, grout curtains, and sheet piles to block the entry of water into the trenches or other foundational areas.

Once the water table starts to increase, you have to take the proactive approach to remove and pump out the water from the entire foundation. While it depends on the type of system you use, make sure to run a thorough engineering analysis to review the entire dewatering process and how it impacts other areas.

Sum Up

In this day and age, there are various exceptional and effective dewatering solutions. In fact, most industries now depend on advanced dewatering solutions to separate solids and liquids effectively. Whether it’s construction, agriculture, or mining, getting rid of groundwater is essential to start or resume operations.

The dewatering process has also become vital to ensure safe and secure working conditions. One of the perks of dewatering is that it prevents environmental contamination of the surrounding area and allows project managers on-site to be on schedule.

Since there are more sophisticated designed buildings and complex architectural structures, there is more important to thrive and survive in a competitive environment.

Whether it’s maintenance, glazing, excavation, or demolition, the dewatering process is at the center of it. Don’t hesitate to seek out the expertise of construction specialists who are aware of specific and updated industry regulations and laws and can help you meet start or restart projects.