Types of dewatering

How does a dewatering system work? What is dewatering, when is it use and methods? Methods of Dewatering Excavations at Construction Site.

The eductor well method is a dewatering process used to control pore water pressures in materials with low permeability characteristics, such as fissured clays or silts. This method uses the venturi principle, where high pressure water is circulated through eductors in the base of each well to create a vacuum that helps promote drainage.

Construction dewatering, unwatering , or water control are common terms used to describe removal or draining groundwater or surface water from a riverbed , construction site, caisson , or mine shaft , by pumping or evaporation. Belt press issues, belt filter press and centrifuge are some of the examples of dewatering. It is also important to choose the best location for discharge , even when you might be far away from water bodies or catch basins. Purpose of Dewatering Sump pumping.

Well point systems with suction pumps. Shallow wells with pumps. This frequently involves the use of submersible dewatering pumps, centrifugal (trash) pumps, eductors, dewatering by electro osmosis, or application of vacuum to well points.

In silts and silt – clay mixtures the use of well points are aided by upper (0m – 0m long) compacted clay seals and sand- filtered boreholes (20cm – 60cm diameter).

Upper clay seals help to maintain higher suction (vacuum) pressures and sand filters increase the amount of discharge. Sump pumping can be effective in many circumstances, but seepage into the excavation can create the risk of instability and other construction problems. Sump pumping can be hugely cost effective, but excessive seepage and ground loss into the excavation can be both expensive and time consuming to deal with and can pose a real threat to the instability of the ground and adjacent structures. The simplest form of groundwater control is sump pumping where groundwater is collected in a sump and pumped away from the excavation site.

Different types of dewatering methods or techniques are available for dewatering of excavation. The different methods available for dewatering of excavations at constructions sites are executed uniquely as each one has a narrow range of applications. Each method is described in detail below. There are many different dewatering methods.

This water needs to be removed in construction projects to keep working as planned and provide a safe work environment. Diaphragm pumps use rubber diaphragms inside the pump casing that open and close to create a vacuum and draw in water. They are low volume but are excellent for muddy materials. A bowl, spinning at high spee separates the water from the solids which are compacted against the bowl walls.

Groundwater can be controlled by means of one or more types of dewatering systems appropriate to the size and depth of the excavation, geological conditions, and characteristics of the soil. Construction sites are dewatered for the following purposes: 1- To provide suitable working surface of the bottom of the excavation. Long-term dewatering individual permits apply to projects that exceed the thresholds and criteria described in Sections 2. These permits must be approved by the District Governing Board.

Two types of individual dewatering permits are available from the District.

Both types are designed to move water from one place to another continuously. A centrifugal water pump uses a rotating impeller to move water into the pump and pressurize the discharge flow.