Dewatering is extremely vital when constructing buildings, powerhouse and dams. Having firm and sound working conditions is indispensable. These structures not only require a dry base for their foundations but also a good water-table-stability in the girth. Although dewatering can be done by techniques such as gravity flow and electro-osmosis, the use of dewatering pumps is the most convenient, efficient and fastest in yielding satisfactory results.
The process is most useful in areas where the foundation of a building to be constructed is below the water table level. Dewatering activities must be done properly to avoid eroding the soil on the construction site.
Normally, dewatering is done by pumping or evaporation before excavation. The type of dewatering equipment to be used will depend on the corrosion potential of the material. It involves the use of a submersible pump or vertical turbine pump. Minor amount of water can always be pumped out by creating a sump.
Colin Adams, the Managing director of Pump Technology, the official sub-Saharan distributor of Grindex pumps Integrated Pump Technology says that one should consider factors such as performance and reliability of the pumps in its applications. He further adds it important to understand the application of the pump and its specific requirements before purchasing it.
Dewatering pump market in Africa
According to World Market for Pumps, the dewatering pumps market in Africa is at an approximate of US $50m as per their 2014 report. This means that Africa has a high potential for dewatering pumps due to its developing state.
Hennie van Niekerk, Regional Technical Advisor (PSP/PUC) of Putzmeister, a South African company that has engaged in a number of dewatering projects including back fill application and alternative fuel projects points out that without dewatering, effective production is not possible.
He further adds that up to date, the African market use centrifugal pump during dewatering process. The process however according to him process can be done much more effective in cutting energy and maintenance cost by the use of positive displacement pumps.
Importance of dewatering pumps
Some surface excavations are jeopardized due to the level of water table. Water tables can become elevated when they receive more water than they drain off. This can be from unusually high amounts of rain, or excess water from higher elevations.
Dewatering is carried out to permit excavation and construction within a dry environment as the water table is lowered. This in turn prevents ground subsidence.
Firm up the soil
Draining of the underground water plays a vital role in drying up the soil, firming the soil and making it suitable for construction. Dry soil stabilizes the landscape and reduces risk of sediments being carried off by water.
Provides dry basement
If not suitably managed and controlled, groundwater can cause problems for excavation and basement construction. These problems can range from nuisance seepage that reduce the efficiency of construction operations, through to major inflows that can result in instability, inundation and even collapse of the excavation. The excavation may flood as a result of groundwater inflows from water-bearing layers of soil or rock.
Kellie West, the Marketing Coordinator for Finish Thompson; a pump manufacturer popular with the mining companies in South Africa, Morocco, Algeria, Egypt and many more African states agrees that its vital to remove water before drilling from flooded areas.
She further adds that one needs to remove water that has accumulated at construction sites and to ensure the continued ability to work in the sites.
Control seepage and pore pressure beneath pavement
High pore pressures occur in soils composed of fine silts or clay’s. Since these soils have a very low permeability, vacuum-assisted dewatering scheme, such as ejector wells, or vacuum-sealed deep wells may serve to draw water into a well for abstraction.
Safety on the job
Wet or muddy ground produces unsafe working conditions for workers. The wet soil can trip workers. Water can also obstruct certain tasks. Its presence can also damage construction equipment or impede operations. Johnston Dan of SANDPIPER says that safety for the miner’s ranks first before any construction or mining activity.
Trends in technology
The market has a price sensitive nature and this is becoming a strenuous factor on overall revenue growth of the global market. China has emerged as a major producer of low cost pumps thus disrupting the market. To overcome this, international pump vendors differentiate their products through additional services and integrating this to advanced technologies. Some of the additional services include customization of the products.
Mr. Adams, Grindex official distributor adds that additional services like offering extends and providing technical and aftermarket support to end-users differentiates one in the industry. Increasing the warranty period to its customers affirms confidence to the customers of pumps one manufactures.
Variable speed drive controls are being used more and more to control dewatering pumps, together with motor protection and remote management systems. Nevertheless Mr. Paul Vermaak of SANDPIPER from the U.S points out that technology trends such as their AOD technology is a proven technology that is most efficient and reliable in the industry. “The AOD can handle, Running Dry and Submersible if flooding occurs, No mechanical Seals, No reliance on alignment or rotating bearings, completely portable, just ‘Plug and play,’ he adds.
Noise Control System Product Type
Buyers across the world prefer less noisy products in comparison to the noisy ones. Although, quieter equipment are more expensive because of their in built sound proofing mechanisms, consumers still buy the products. Quieter equipment is more beneficial and economical over a period of time.