February 2011, Vol. 66 No. 2
Features
Significance Of Dewatering Can’t Be Overlooked
Dewatering is a necessary aspect of many underground construction projects. Construction sites near coastlines, rivers, other bodies of water and in other situations may require 24-hour dewatering every day. Heavy rains may fill work areas during storms.
Whatever the source of water in pits and other excavations, no work can be done until the water is removed.
“My father was a contractor for 42 years, and I grew up in the construction business,” said John J. Struzziery, P.E., principal engineer, Kleinfelder/SEA, Cambridge, MA. “I’ve always remembered something he told me: ‘If you control the groundwater, you can do anything.’ ”
Throughout his career as an engineer, Struzziery frequently has had projects that require dewatering. It may simply require pumping water and redirecting or “recharging” it into to the ground at another location or can require deep wells with pumps placed to remove water.
“Different conditions require different methods,” Struzziery said. “For our company’s projects, we specify dewatering criteria and the methods to accomplish the task.”
Pumps
No matter the source, pumps are the heart of most dewatering applications.
Ron Askin, Godwin Pumps vice president and director of sales, said if the dewatering system requires lifting the water to a higher elevation, it will require pumping.
“There are a wide variety of pumps available depending on the application, water level and permeability of the soil and required pumping distance,” said Askin. “The most common are automatic self priming pumps, centrifugal and rotary lobe well point pumps and submersible dewatering pumps. A dewatering system becomes necessary when the construction conditions require the work be done in a dry condition. This may be for a variety of reasons including soil compaction, sealing joints and structures, or just to increase productivity.”
In addition to pumps, said Askin, dewatering systems generally require diesel or electric power sources for the pumps and a piping system — hoses, valves, fittings, etc. — to get the water to the disposal location.
“Also important with dewatering systems,” he added, “are controls that automatically stop and start pumps, dependent upon the fluid level, and will also adjust the speed to match the water infiltration conditions.”
Simple dewatering needs often are accomplished by the general contractor or subcontractor responsible for underground construction portions of a project. Dewatering pumps are widely available for rent from pump companies and their distributors and equipment rental specialists.
Specialists
When a dewatering system is required, a specialist often is called. Some major pump companies — including Rain For Rent, Godwin and Thompson Pump — not only sell and rent pumps, but offer turnkey dewatering services. Some project owners or the engineering firms design dewatering systems for the projects, others involve the dewatering subcontractor in design and providing equipment and operation.
“The greatest benefit of a specialty dewatering contractor is the availability of a variety of solutions and knowledge of local soil conditions,” said Godwin’s Askin. “There is always some risk when working in wet conditions. It’s a great comfort to the prime contractor if his pump supplier has done similar projects in the area.”
Suppliers/experts
Godwin provides a variety of pumps and services including dry prime models, well point pumps, submersible dewatering pumps, and piping systems, including well points; HDPE pipe fusion; job set up and breakdown, pump watch, and system maintenance.
“All of our equipment and services are offered any time of day, any day of the week,” said Askin.
Thompson Pump operates 20 full-service, factory-owned locations across the United States, said Kirsten Petersen Stroud, Thompson Pump’s marketing manager. “Each location provides sales, rentals, repair, installation assistance and pump-related accessory needs. We are also aligned with a network of Thompson Pump factory-authorized distributors around the world.
“A specialist has the experience and knowledge to assure the job is done correctly, saving time and money. A specialist can offer full-service capabilities including engineering systems, dewatering design, installation, equipment, and monitoring 24 hours a-day, 7 days a week.”
She added that all Thompson branches and service centers are equipped with full inventories of pumps for sale or rent, repair parts and a full assortment of pipes and accessories. Each Thompson Pump location has the ability to complete the entire pump project, from planning and development, mobilization and installation, to system operation and maintenance. This turnkey ability provides full-service installation of complete packages.
In addition, Stroud said a full rental fleet with a variety of pumps is available at every Thompson Pump Service Center, and HDPE pipe fusion technicians are available for any project. Each factory-owned location is fully equipped with parts and equipment that can be immediately dispersed to any job site.
Rain for Rent has been providing solutions for complete liquid handling solutions since 1934. Rain for Rent’s staff includes experienced professionals that can design and install a system that will provide a solution for each customer’s unique project in an efficient and cost effective manner.
Solutions, be it water filtration system or dewatering system, can be tailored for a specific industry job site, from the simplest liquid-handling solution to the most complex, large flow bypass pumping job.
With more than 90 locations nationwide and international operations in Europe, Canada and Mexico, BakerCorp designs and constructs dewatering systems among many specialized services, including bypass pumping and excavation shoring. In addition to the utility market, BakerCorp provides integrated services for general construction, oil and gas, industrial services, environmental remediation, and many other markets.
Necessity
“Dewatering is necessary at any point where the water will impede the progress of the project,” said Carroll Hunnewell, BakerCorp eastern regional pump manager.“Excavations should be ‘ground dry,’ and our locations can supply the equipment and expertise needed for a multitude of dewatering applications.”
A typical system, said Hunnewell, will include smaller lower head higher volume units within the tunnel system that typically feed larger higher head units to pump to the surface. Surface water will either be contained and treated on site or fed into a local municipal treatment system.
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“While the general contractors is responsible for dewatering the site,” Hunnewell said, “most often they will rely on a dewatering company for their expertise in developing a system, because the specialist most often will understand the soil dynamics, hydraulic composition of the soil as well as the best methods to efficiently dewater the site.”
FOR MORE INFO:
BakerCorp.,800-BAKER 12, www.bakercorp.com
Godwin Pumps, (856) 467-3636, www.godwinpumps.com
Rain-For-Rent, 800-742-7246 , www.rainforrent.com
Thompson Pumps, 800-767-7310, www.thompsonpumps.com
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