WHEN YOU GOOGLE “DEWATERING,” some of the first results yielded are the Wikipedia page for the term, followed by the website for Griffin Dewatering Corp. While that pretty much sums up the company’s place in the industry, Griffin didn’t just rise to the top of the dewatering business overnight.

Griffin has been building a resume in the industry for nearly 80 years. Dewatering essentially refers to the process, or different processes, of groundwater removal. While this type of work is generally done near a coast where water tables are higher, dewatering is a system that is often needed on large jobs with deep excavations or jobs where a certain amount of water removal is necessary to complete the work, regardless of the location.

Getting Started


Griffin has been in the dewatering business when Tim Griffin started the company in 1934. At the time, there were few companies doing dewatering and the ones that did perform the work were mainly on the East Coast. Griffin started the business in a small factory in the Bronx borough of New York City, eventually passing it on to his son David, who ran the company until the early 1980s.  Since the days in the Bronx, Griffin has expanded to eight locations throughout the country and the company has maintained a reputation of being one of the premier dewatering companies in the United States.

Today, Griffin is a full service provider of construction dewatering, stormwater systems, groundwater treatment, slurry trenches, drilling services, relief wells and pump equipment manufacturing. The company does over $30 million of work annually. 

Tom Minihan, vice president of Griffin Dewatering Midwest, L.L.C., said Griffin’s innovation and ability to handle tough jobs has allowed the company to be successful for so many years. Minihan has worked for Griffin for the past 16 years and has 37 years of experience in the dewatering business. He has groundwater control expertise in a variety of systems and has previous experience designing and manufacturing dewatering equipment.

Since the current ownership took over in 1992, the company has begun focusing more on manufacturing and selling custom equipment in addition to expanding facilities to cater to the international market of dewatering.
“What makes Griffin different than other dewatering companies is its innovative, aggressive techniques,” Minihan said. “There are so many different aspects to the company other than the dewatering, like contract management, rentals, sales and service. We can do small jobs like a manhole tie-in all the way up to dewatering for sports arenas.”  

Minihan has been involved with some of Griffin’s major projects over the last several years, including renovations at Soldier Field in Chicago, the Elm Road Power Generating Plant in Oak Creek Wis., the BP Whiting Refinery Canadian Crude Operations Expansion in Whiting, Ind., and the Potawatomi Casino Expansion in Milwaukee, Wis. He said recently the company has been increasing its outreach to dewatering markets outside the United States, expanding mostly equipment sales into Canada and Mexico, and eventually reaching Central and South America, as well as Europe.

Jerry Soto, a purchasing manager for Griffin, agrees with Minihan that the reason for the company’s continued success is the ability to provide several different services related to dewatering.

Soto has more than 25 years of experience in pumps and their applications. He is involved in installations, testing of electric submersible pumps, design, estimating and project management of groundwater control systems, as well as coordinating Griffin’s pumps on large jobs around the country.

Soto said he believes diversity and experience are also a huge part of being successful. “Diversity has kept us afloat and has helped promote us,” he said. “We don’t just rely on certain parts of the company. It’s the experience of all the people within the company that have helped push us forward.”

Dewatering Systems and Equipment


Some of the company’s major dewatering jobs over the years have included sports arenas, power plants, treatment plants and hospitals. Griffin specializes in several different groundwater removal techniques, most notably, wellpoint systems, open pit sumping, the SilterVac point system, deep well systems, horizontal wells and eductor systems.   

The wellpoint system is one of the most common and adaptable pre-drainage methods used in dewatering. The system can allow for water to be pumped at a few gallons per minute in fine sandy deposits and up to thousands of gallons per minute in coarse sands and gravels. This method consists of multiple wellpoints spaced along a trench or excavation site, all of which meet at a common header which is attached to one or more pumps.

Minihan referred to another method Griffin uses as open pit sumping, a system that is effective in low permeable soils, clay and sand. Open pit sumping can be used for dewatering in bore pits, such as a road bore, and uses electric submersible and hydraulic drive pumps to extract the water.

Another system Minihan stressed was a vacuum system called the SilterVac point system. This is a method that allows dewatering in depths of about 20 ft. The system involves geotextile points that are centered around a bore pit to intercept layers of sand that contain water. The SilterVac system is generally used on jobs with a higher flow rate of water in the given area. The system is performed using vacuum-primed centrifugal pumps ranging from 4 to 16 in. in diameter, depending on the volume of water needed to be pumped.

The deep well system is a versatile process that can pump both high and low quantities of groundwater for aquifers that exist deep beneath the excavation site.  Deep wells can almost always be used for water removal deeper than 20 ft and up to 90 ft deep. These types of systems involve individual, submersible pumps for each well rather than multiple wellpoints that connect to a common pump. Deep wells are high volume systems that can pump up to thousands of gallons of water per minute.      

Horizontal wells are another system that can be implemented using horizontal directional drilling (HDD) and can reach depths of 30 to 50 ft, or sometimes deeper. This system can also be used in trenching limited to about 19 ft, generally hooked up to an above-ground pump, but can be used with submersible or vacuum-primed centrifugal pumps as well. Minihan said as far as green initiatives, the horizontal well dewatering is becoming widely used in the company.

“We see it as a strong candidate for having low negative impact on the environment,” Minihan said.
Griffin also uses eductor systems for dewatering, specifically in deep excavations. According to Griffin, this system is particularly effective in soils with multiple, tough layers. The eductors are installed at relatively close spacing similar to the array in wellpoint systems, but require only a single stage to produce drawdowns of up to 100 ft or more.

Certain variables must always be taken into consideration before implementing any of these methods, particularly the physical layout, conditions of the site or trench to be dewatered.  The permeability of the site, the amount of water to be pumped, depth of the wells and arrangement of ground layers must all be carefully measured.

Minihan said the type of system used always depends on the soil conditions. In fact, Minihan himself created a custom filtration system that uses geotextile fabric to rid the groundwater of sediments during dewatering.  

“It’s actually similar to putting a handkerchief over a pipe and using that to filter out rock and dirt sediments from the water being pumped,” he said.

This was a technique that he personally developed as an alternative to the traditional slotted-screen approach. During dewatering, it is necessary to filter out dirt and other soil sediments, taking out only clean water, due to regulations by the Environmental Protection Agency (EPA).  

Recent Notable Projects/Contributions


In 2006, Griffin was honored by the American Society of Civil Engineers when the OPAL (Outstanding Projects and Leaders) Award was given to contributors to the Saluda Dam Remediation Project. Griffin was recognized for its work, along with SCE&G, Paul C. Rizzo & Assoc., Barnard Construction Co., and Kleinfelder, on the Saluda Dam Remediation Project in Columbia, S.C.  The Saluda Dam is located about 10 miles west of Columbia on the Saluda River. In 1986, an earthquake near Charleston caused the dam to fail, resulting in flooding. For the remediation project, Griffin provided dewatering services to the contractors that worked to construct a backup dam directly next to the original Saluda Dam in an effort to prevent possible future flooding.

Griffin also worked with the U.S. Army Corps of Engineers in 2011 on the Seabrook Floodgate Structure in the Industrial Canal in New Orleans. The floodgate structure was essentially a cellular-style cofferdam, build to reduce the risk of storm surges pushing water into the Inner Harbor Navigation Canal and flooding areas of the city. In late April, Griffin pumped 15 million gals of water from the site using forty-two 10-in. diameter, 75-ft deep wells outside the dam perimeter to lower the groundwater table and relieve external hydraulic pressure. The project was notable due to the high permeability of the soils outside the perimeter of the dam.

International Outreach and Going Forward


Minihan said that in general, the United States has recently been increasing its competitiveness in the international construction market and the dewatering industry is no exception. According to Minihan, U.S. exports of construction equipment in 2010 were up 28 percent and in 2011, up 43 percent. Minihan said it is a good sign for the industry as a whole and that exports have increased because the world’s need for equipment is growing.

“We are looking ahead to expansion in construction contract management, Web-based sales and basic expansion of our product line,” he said. “Water quality management equipment is a key item for us. We are also looking to increase custom piping and custom above-ground storage tanks. As infrastructures continue to expand, more sophisticated equipment will be needed.” 

As far as Griffin’s future, the company hopes to continue to do what it has done so well for almost 80 years. Minihan and Soto both stressed Griffin’s desire to continue adapting to trends in the industry, but also expand its own products, emphasizing that Griffin is much more than a dewatering contractor, involved extensively in manufacturing, sales, rentals, time and materials, engineering and construction management.
“In the future, I believe we will continue to be at the forefront of dewatering, but we will also get more into product sales and manufacturing and eventually grow into other fields,” Soto said. “We would like to think requests keep coming in because we are making reliable equipment.

“We are our own worst critic. When things work, we push that direction. When things don’t work, we are able to fix them pretty quickly.”

Andrew Farr is an assistant editor for Trenchless Technology.