Dewatering Techniques: Pros & Cons of Each Method

In simple terms, dewatering removes water from solid material or soil through wet classification. The primary purpose of dewatering on construction sites is to reduce the water level in the ground. Also, since it will be practically impossible to build a solid foundation on wet soil, construction engineers have over the years adopted dewatering as a simple solution to deal with running sand, sewers, basement, and tunnel. 

Why dewatering?

Over the years, different questions have been raised on the efficacy of dewatering. There are also questions being raised to know if there are other alternatives to dealing with water levels below the soil other than dewatering procedures. After all that being are being said and done, the purpose of dewatering services include:

• * To drastically reduce the pressure of air in tunnel operation.

• * Creating a dry area on the construction site will enable the construction project to go on smoothly without delay.

• * Dewatering is used to support foundation materials.

• * Dewatering helps in containing and managing the embankment of seepage in dams.

What are dewatering methods?

1) Well point 

This is the most common and cheapest dewatering method. Well point dewatering method is best for hydrologic conditions and most soil. The process involves using a perforated metal or plastic metal of 7.5 or 5.5cm diameter, which will be covered with a screen. However, there is no universal length for the pipe. It varies from 62cm to 122cm. To use this method, the pipe is designed with water holes on it.

To extract water quickly, the pipe will be inserted into the ground either by jetting or driving. On the other end, the upper end of the pipe also has a pipe connected to it. Once the pipe is driven into the ground, the pump extracts the ground water through the header pipe straight to the other end on the outer surface.

2) Educator well

This method shares some similarities with the well point method. However, the difference is that while well point uses a vacuum to draw ground water to the surface, educator well uses high-pressure water to pump out water to the surface. Also, educator well can link to different well points. This is why most construction companies prefer this method because it saves time.

Other dewatering method includes open slump pumping and the deep well point method.

What are the necessary precautions that must be strictly adhered to while working on a dewatering project?

• * Avoid pumping water directly into slopes or sloppy areas.

• * Before discharging water extracted from the ground, the chosen area for discharging must be certified safe for the purpose.

• * Dewatering should not be embarked upon when it is raining.

• * Close supervision is essential when dewatering. This will help to take caution if any threat comes up during dewatering.

• * Water extracted should be discharged in a forest buffer zone for safety purposes. 

What is the advantage of dewatering?

Safety

Dewatering helps improve the safety of the people working on the construction site. This is because standing on the water can be harmful. When ground water is dewatered, it reduces the chances of sliding and workplace injury.

Stable soil

Once excess water is extracted from the ground, it helps in ensuring stable soil. Stable soil is vital because it reduces the chances of mudslides.

Environmental protection

Standing water can cause a negative environmental impact. Some of these impacts include:

• * Serving as a breeding ground for mosquitos and other diseases.

• * Stable water can accumulate debris that is toxic to the immediate and larger environment.

Final thought 

Ground water or stable water dewatering is an age-long practice that has continued to serve the interest of humanity. Despite the advantage of dewatering, you must take necessary precautions. Also, to ensure the task is carried out effectively, it should be handled with someone with a wealth of experience on the job. Effective dewatering solutions require the use of specialised dewatering pump equipment.