Aquifers, Wells, Drilling Rigs, and Pump Hoists

Then and Now

By Ed Butts, PE, CPI

Many aspects and procedures of constructing a water well and pumping system have changed greatly since
1975.

Water wells are drilled today at various angles with aquifers containing new, different, and various chemical contaminants and to extreme depths. Then you also have wells being drilled for other purposes such as geothermal, dewatering, aquifer storage and recovery (ASR), contaminant monitoring and recovery, and deep borehole injection uses.

Past common methods of well construction, such as cable tool machines, have largely been replaced with faster drilling methods. Some were still evolutionary or not around in 1975, including sonic and dual tube rotary drilling. In addition, excessive drafting of some aquifers has resulted in increased regulation and the need for deeper wells.

But even considering all these revisions, the main objective of drilling a water well has not changed—to obtain a safe and adequate source of groundwater. This month, as part of our retrospective look back on the industry over the past half century, we will examine the many changes and advances that have occurred with aquifers and well drilling and pump installation methods along with the increasing transition to electric vehicles.

Obviously, there are numerous current issues with aquifers and more advancements in well drilling equipment and pump hoists than cited herein, but due to space constraints, I am including what I consider to be some of the most notable.

Well Construction in 1975

Although the following will vary with regions and local customs, most domestic wells drilled in 1975 where I lived and worked were 6 inches in diameter with a smaller minority of 4-inch-diameter wells. Shallow-well and deep-well jet pumps were and are still commonly used.

Most of the cased wells constructed for municipal, irrigation, and industrial use typically varied in size from 8 inches to 16 to 20 inches or larger. Most new drilled wells utilized cable tool, mud rotary, or air rotary methods with a minority of wells drilled using auger, bucket, or reverse rotary methods for larger or shallower wells in unconsolidated formations.

Rotary methods primarily used either tophead or rotary table drive with traditional drag bits or tricone roller bits, primarily for unconsolidated formations. The tricone roller bit was invented by Hughes Tool Co. in 1908 and was the common drill bit used for oil well drilling at the time.

Mud rotary drilling utilized a bentonite mud and water mixture or water itself, circulated down the drill rod to the bit, and then upwards in the annulus between the drill rod and borehole to the surface. The mud is used to lubricate the bit as well as dislodge, lift, and transfer materials (i.e., cuttings) from the borehole to the surface.

Another rotary method used in our region, primarily for unconsolidated formations, was reverse rotary. As opposed to conventional mud rotary, reverse rotary injects the mud-water mixture down the annulus between the borehole and drilling tools and is extracted through the drill bit and up the drill rod and stem to the surface. The combined drilling fluid and cuttings are then diverted to a large settling pit or pond where a mud pump returns the drilling fluid to the borehole.

This process requires a greater water supply and continuous circulation to maintain the integrity of the borehole than mud rotary but is typically a faster drilling procedure that facilitates the removal of larger gravel and some boulders. This method was commonly used for larger irrigation and municipal wells.

Most wells drilled in semi-consolidated formations (sandstone and shale) and consolidated (mainly basalt) formations generally used the air rotary method. In air rotary drilling, compressed air is primarily used as the drilling media. The needed volume and pressure of air is developed in an auxiliary or deck-mounted compressor and forced down the drill pipe to the drill bit, often a tricone or down-the-hole (DTH) hammer.
The DTH hammer uses a uniform reciprocating percussive action to penetrate the formation, with the air carrying the cuttings back to the surface. Most new wells used welded or threaded joints on ASTM A-53-B steel well casing.

Domestic well testing usually consisted of a minimum one-hour bailer or air test while testing of industrial, irrigation, and municipal wells often consisted of a 4-hour to 24-hour pump test. Most of the new wells drilled in known regions could be reasonably predicted for depth, formation type, and yield from historical and anecdotal background knowledge before beginning construction.

Changes to U.S. Aquifers, 1975 to 2025

The water well industry has witnessed significant changes and advances since 1975. One of the most obvious and bothersome of these is the widespread decline in static and pumping water levels and production in various aquifers and wells throughout the United States.

Here are just a few impacted aquifers throughout the United States that are becoming increasingly regulated.

Much of this, particularly in the central region of the country, can be attributed to the pumping of municipal and agricultural wells exceeding the recharge. An extreme example of this is in the Ogallala-High Plains Aquifer. It is one of the world’s largest groundwater sources, existing from South Dakota down
through the Texas Panhandle and extending across portions of eight states with the breadth and depth of the aquifer generally decreasing from north to south.

The saturated thickness of the Ogallala Aquifer in 1997 after several decades of intensive withdrawals is shown in Figure 1a. Regions where the static water level has declined during the period between 1980-1995 are shown in Figure 1b in yellow and red; regions where it has increased are shown in shades of blue.

The draft of the Ogallala Aquifer has continued into the 21st century and will into the foreseeable future. Depletion between just 2001 to 2008 is about 32% of the cumulative depletion during the entire 20th century.

Another impact in groundwater use since 1975 is the increased regulation on permitted uses and withdrawal rates for some aquifers. Another presently challenged aquifer is the Columbia River Basalt Group in parts of Oregon, Idaho, Nevada, and Washington.

The Columbia River Basalt Group (CRBG) was formed by the ancient Missoula Floods, which exposed the lava flows generated by regional volcanic actions. It engulfs about 63,000 square miles of the Pacific Northwest, forming a large igneous flood basin (aquifer) with an estimated volume of 42,000 cubic miles.

The CRBG possesses a finite volume of water storage, high withdrawal rates, and limited sources and volume of recharge.

The aquifer has experienced substantial declines in static water levels over the past 50 years with new construction and usage permits carefully controlled, or in many cases, totally declined.

The CRBG is often a prime candidate for aquifer storage and recovery (ASR) practices that is already being practiced in many regions of the country.

The final example is the Edwards Aquifer in Texas. The Edwards Aquifer Authority regulates withdrawal permits, transfers, and groundwater conservation plans under authority granted by the Texas legislature.

Groundwater conservation plans are required for permit holders who withdraw more than 3 acre-feet (977,400 gallons) per year unless irrigators can prove their water use is more than 60% efficient. Conservation plans require the use of best management practices as determined by the aquifer authority.

Advancements to Well Construction Methods, 1975 to 2025

Monitoring in 1975 wells was largely constructed from 4 inches and larger casings. Today, monitoring wells are commonly drilled using non-metallic casing sizes of 1 inch or 2 inches. In addition to extracting and monitoring groundwater quality parameters, modern monitoring wells are also used for monitoring groundwater levels during well testing and for establishing a cone of depression. Monitoring wells are
typically constructed using PVC casings and stainless steel or PVC screens.

Many of the other changes in water well drilling have occurred with the diversity and expansion of rotary drilling equipment, with an accompanying decline in the cable tool method. Most of this can be attributed to the much faster penetration rates experienced with the air and mud rotary versus cable tool methods.

As opposed to most 1975 models, many new rotary drilling machines are now lighter in weight and designed with minimal masts. They are often being built with mast-mounted carousels (Figure 2) and truck-mounted storage bins for additional drill rods. This is safer for personnel and speeds up handling drill rods, and in many cases, eliminates the need for a second support vehicle specifically used to transport drill rods.

One of the other principal differences to water well construction since 1975 is the widespread use of PVC and fiberglass-reinforced plastic (FRP) well casing and liner over steel. To use PVC or fiberglass pipe as well casing, the legal steps to get it approved had to be conducted in each state.

PVC well casing is offered in ASTM F-480 compliant Schedule 40, SDR 17, 21, and 26 ratings. Even though most PVC well casing and liner utilize glued interference joints, a recent addition uses a grooved spline and gasketed joint for faster assembly.

Although more resistant to corrosion and brackish water, both plastic casing alternatives must be used with caution during well sealing as the heat of hydration associated with the curing of Portland cement can result in high temperature spikes leading to potential well casing failures.

Down-the-Hole Hammers

Down-the-hole (DTH) hammer (Figure 3a) drilling has made it easier for contractors to drill wells faster and more efficiently, particularly using air rotary drill rigs in hard rock.

Until the beginning of the 20th century, well drilling in hard rock was mostly done by cable tool percussion drilling. A chisel mounted on a cable was repeatedly dropped into the borehole and pulled up again. This method has been used for thousands of years and is still used in developing countries.

Air-flushed drilling with top hammers began in the mining industry in Sweden in 1873, while down-the-hole drills with air flush and activation first became operational in 1950. Halco, in close cooperation with Stenuick Freres, pioneered the widespread development and distribution of the down-the-hole hammer, primarily for mining and blasthole applications, during the 1950s. These were mainly used throughout the
United Kingdom, Australia, New Zealand, Africa, and India.

Both tophole percussion and DTH drilling were synonymous in the 1960s with the use of air flush. It is now generally recognized and widely accepted as the primary water well drilling method in hard rock. Down-the-hole hammer drilling has been a feature of dam anchoring and rock mass grouting in the U.S. for several decades.

This rotary percussive drilling method was synonymous until recently with the use of compressed air. Within the last two decades, however, increasing use has been made of water-activated, down-the-hole hammers (WDTH). A hydraulic-driven DTH drill was patented in 1983. It used a valve to switch the hydraulic pressure driving the piston.

In the United States, DTHs driven by compressed air were introduced during the 1960s. The Directional DTH system, patented by Atlas Copco, was first used successfully in 2012 by drilling crews in the Marcellus Shale region of the United States to steer percussive drilling equipment.

Conventional down-the-hole hammers typically use carbide button bits (Figure 3b) and are available in sizes from 3½ inches up to 60 inches. Other DTH variants have been developed over the last 20 years based on air activation and flush. These include reverse circulation and dual-fluid system using air as the activator but permitting water flush.

Casing Hammers and the ODEX System

Water well contractors have several options available to them when determining the best method to use for their formations and casing advancement needs. Two common methods employ an underreamer or casing hammer.

A casing hammer (Figure 4) is a well-established alternative for advancing well casing in situations where the hole cannot otherwise be kept open, such as drilling through unconsolidated formations.

A rotary tophead rig may be equipped with a casing hammer powered by compressed air, hydraulic fluid, or mechanical power that concurrently drives the casing as drilling progresses. Typically, a DTH hammer, underreamer, or tricone bit is used to open a hole ahead of the casing and is then retracted inside the casing while the casing is driven with the casing driver.

The striking action of the casing hammer can be reversed to aid casing removal. Casing hammers have been developed for both cable tool and air rotary methods. At one time, air rotary drilling through alluvial formations was difficult, if not impractical. The introduction of the ARCH (air-rotary-casing hammer) method, however, allowed the use of air rotaries for alluvial wells.

Some of the most common applications for casing hammers are geothermal water well drilling, mini/micro piling, ground stabilization, and foundation work. The ODEX system is economical for shallow and short holes.

At the start, the ODEX eccentric reaming wing is in a closed position, and when the system starts drilling at the end of the casing, the reamer swings out in the drilling position, and thus enlarges the hole for the casing to advance. With its eccentric reaming wing, ODEX is acceptable for drilling and driving casing through unconsolidated formations including silt, clay, sand, and gravel.

Dual Tube Reverse Rotary

Another fairly recent addition to the rotary method is dual tube reverse rotary. The dual rotary drilling concept was developed by Barber Industries and commercialized with the introduction of a dual rotary rig in 1979.

This technology was acquired in 1993 by Foremost Industries LP of Calgary, Alberta. It maintains borehole stability by advancing an outer casing, which allows advancement where other overburden drilling systems are generally unsuccessful. Once the casing is in place, well installation can be accomplished in a controlled environment.

The dual rotary technique is being used successfully where unconsolidated formations (glacial till, sand, gravel, and boulders) make it difficult to drill a cased borehole using conventional mud rotary drilling techniques.

The dual rotary drilling rig utilizes a lower rotary drive unit to advance casing through unconsolidated overburden. Rotational forces are effectively transmitted to the casing through power-operated jaws. A carbide studded shoe, welded to the bottom casing joint, enables the casing to cut through the overburden.

The role of the drill pipe is to transfer sufficient rotational torque and weight to the drill bit. A hybrid of dual tube reverse circulation drilling is known as dual tube flooded reverse (DTFR) (Figure 5). It is an environmentally friendly and non-invasive drilling process. DTFR generally drills with the borehole fluids at their naturally occurring level.

The dual tube method has distinct advantages over conventional rotary drilling methods as lost circulation in extremely porous formations, common to conventional mud and reverse rotary drilling, is not as risky or likely with dual tube methods. All drilling fluids can be contained as well, creating less danger for the potential loss of or contamination caused from drilling fluids.

DTFR uses a combination of natural formation water, added clean water, and compressed air to mobilize the drill bit cuttings to enable the advancement of large-diameter borings in formations ranging from unconsolidated geology to medium hard and fractured rock.

DTFR applications are typically used for projects entailing large-diameter water wells in sedimentary and metamorphic broken or fractured formations with depths commonly ranging from 500 feet to 3000 feet where environmental protection is important.

The dual tube rotary methods can be used to drill deep, large-diameter applications including municipal wells, irrigation wells, industrial wells, environmental wells, exploration boreholes, injection wells, aquifer storage and recovery (ASR) wells, dewatering wells, elevator shaft drilling, construction drilling, and various other types of drilling applications.

Sonic Drilling

A fairly recent addition to water well drilling equipment is sonic drilling. Sonic drilling technology (Figure 6) is based upon the principle of creating high frequency, resonant energy that results in vibration.

The hydraulic motors on the exterior of the head oscillate offset internal weights at speeds reaching 5000 RPM. As a result of the offset counter rotating weights, it creates a downhole vibration between 50 to 140 hertz or more to advance a core barrel or casing into subsurface formations.

Approximately 12 rigs using early sonic technology were constructed from 1974 to 1983 and used in different applications. Unfortunately, these first machines experienced frequent breakdowns and lacked appropriate tooling to withstand the associated vibratory forces.

The recession of the early 1980s discouraged Hawker Siddeley, an early pioneer in sonic drilling, from continuing development work in this field. However, these original sonic rig heads and drill rigs are still used today.

There are situations when a client or the application prefers to avoid the use of drilling mud, air, or even clean water while drilling. This is an advantage as sonic drilling does not necessarily require air or drilling mud while drilling. This makes sonic drilling the preferred method for many water wells as well as geotechnical holes, observation and monitoring wells, geo-construction, and other environmental applications that require clean formation samples.

The primary sonic advantage is its ability to constantly case the borehole after it advances the tooling to the next interval. This minimizes the risk of lodged tooling below ground surface.

If the situation should occur that the override casing begins to tighten, the sonic drill can place a larger casing to reduce the skin friction on the downhole tooling without removal of the already installed drill steel. This allows the sonic drill to maximize its depth capability, ranging from 250 to over 500 feet, depending on the situation, formation, and diameter.

Offering excellent performance in overburden soil conditions, the sonic drill head can drill three to five times faster than other methods without the use of drilling mud and with 70% to 80% less waste. Sonic drills can also provide continuous undisturbed core samples to a depth of 300 feet, a significant advantage over other drilling methods.

Casing While Drilling

Although the casing while drilling (CWD) method has been historically used for cable tool drilling and has been quite popular for gas and oil well construction for more than half a century, those using the rotary method for water wells have been possibly using it for only the past 30 or so years on a much more limited basis.

This method is commonly known as a form of a casing advancement system (CAS). For rotary drilling, there are several different and valid reasons for using CWD as well as variations. This includes encountering unstable or caving formations or flowing sand. There are three primary types of CWD systems:

1. Non-retrievable CWD system
2. Retrievable CWD system
3. Drilling with liner system.

The first variation is to attach the bit permanently to the drill pipe with no intent to retrieve the bit. This is generally the cheapest and simplest method. The borehole is advanced with the casing, and once reaching the final depth, the casing is perforated in the region of productivity.

The retrievable casing while drilling system strikes a balance between conventional drilling tools and CWD. The main advantage of this system is that it can be steered and used with both conventional drilling and logging while drilling tools.

Drilling with liner works in much the same way as the previous two systems, except it does not involve the use of a casing drive system. The liner hanger setting tool is connected to the drill pipe and then attaches to the power swivel at the surface.

In rotary water well construction, the most common system uses a latching bit, and the casing is rotated with the tophead drive. This is a fast, efficient, and economical system, but consideration must be given to the strength of the string, specifically the casing wall thickness and the type of joint.

When using threaded joints, the threads should be of a premium quality and rated for well drilling. On larger casing sizes (more than 12 inches), welded joints are generally preferable as they are stronger and will not break at a thread root.

Although the CWD method has inherent limitations as well as applications, its use has been supplanted in the United States by other methods such as reverse and dual tube rotary.

However, as the advantages of this method for certain formations become more widely known, drill rig manufacturers will undoubtedly develop the machinery and techniques needed to compete with other drilling methods. As technology continues to evolve, the increased use of CWD will likely continue to become even more refined, helping to drill faster, safer, and more efficiently.

Pump Hoists

As relatively new equipment to the water well industry, pump hoists have largely kept pace with the type and weight of well pumps. Early pump hoists often consisted of a manually set A-frame or tripod assembly. These were largely used with chain hoists to install deep set rod and jet pumps set on galvanized steel pipe as well as some vertical turbine pumps.

The early days of pump hoists also included actual or modified cable tool rigs and cranes. Three-line cable-tool drilling rigs typically used the casing line for pulling and setting pumps while two-line machines generally used the sand line. The friction drive and brake nature of a sand line for pump servicing often resulted in inconsistent setting speeds with pipes often bouncing off the support plate or elevator.

Manufactured pump hoists before 1975 were still largely homemade rigs, with the mast and winch often powered with friction lines, electric worm gear drives, or hydraulic motors. Before the widespread popularity of submersible pumps, these units often consisted of a single structural steel box tube or
a cross-braced channel shaped mast without an extension. Therefore, the pulling height was often limited to 15 feet to 20 feet, ideal for 10 feet of pump column and shaft but impractical for 20-foot pipe lengths.

Pump hoists used for deep set vertical turbine pumps were often equipped with cable tiebacks or a stiff leg behind the main mast (Figure 7), which assisted with the heavier weights of vertical lineshaft turbine and early submersible well pumps.

Many early pump houses for larger pumps were built on tracks to enable moving the building away from the well to provide room for the pump hoist and stiff leg. The primary commercial manufacturers of domestic pump hoists in 1975 were Smeal, Monitor, and Cyclone, with the Smeal models 3T and 5T the most popular. During the late 1970s, Smeal also made a rotating pump hoist patterned after a 5T, called the
S5T.

Moving forward to 2025, most commercially made pump hoists are quite similar in construction and function. In essence, what manufacturers deem the best commercial model drives their designs. However, all models typically have a hydraulically raised mast, with the extension extendable using either an internal hydraulic cylinder or mechanical reeving means.

The extended mast on most modern pump hoists ranges in overall height from around 30 feet to more than 50 feet. The masts generally possess adjustable laybacks up to 20 feet with the distance determined from the hoist frame to the center line of the cable. This is a distinct advantage for a modern pump hoist as many wells and pumps inside of pump houses can now be successfully accessed.

Most modern pump hoists have two hydraulic leveling jacks in the rear and at least two or three additional reels for ancillary or different purposes. All are usually driven by a hydraulic motor, which itself is driven by a hydraulic pump powered by the engine of the truck using a power take-off (PTO) or a separate deck engine.

The use of hydraulics provides precise control and positioning of a load, a definite advantage over friction-line machines. To lessen wear on the truck engine, some homemade hoists use a smaller deck-mounted engine to run the hydraulic pump.

The main line of the pump hoist usually performs the heavy lifting of the well pump. The main line can usually be routed through a traveling block to increase the capacity of the hoist. This can vary from a two-part line up to a four- or five-part line. Most commercial pump hoists are capable of lifting from 1000 pounds to up to 25,000 pounds on a single main line, with the capacity doubling for every additional line.

The top of the mast must be secured to an anchor to gain this increase in most cases. They also utilize an automatic reeving and braking mechanism to support the load at any position although some hoists use a self-locking worm gear.

Larger pump hoists are generally built with an A-frame configured mast and cable tiebacks for added strength. Most machines can also be equipped with various options such as a breakout wrench, remote control, front leveling jack, extended mast, hydraulic oil cooler, second sand line, third tail-out line, cathead, and powered brake for the sand line.

The sand line has a lighter capacity than the main line and travels much faster. It is intended to operate a bailer to bail sediment from the well to clean it before installing a new pump. Some larger pump hoists are also equipped with a third line which in some cases is used to extend the mast extension but is generally used as an auxiliary line for tailing in or out or pulling lineshaft/oil tube assemblies and tailing in or out pipe for larger vertical turbine and submersible pumps.

Most commercially made pump hoists are currently provided from various manufacturers including Hunke, Pulstar, G&R, Semco, and Kyle (swinger).

Another advancement to pump installation and pulling tools is the portable pump puller, also made by several manufacturers. These are hand-carried or cart-mounted portable hoists that are often controlled with a single person and use two or three pneumatic tires or opposing traction belts, oriented around or opposing the pipe.

The tires or belts are frictionally applied against the drop pipe using hydraulic, electric motor, or worm gear powered winches to provide traction during pulling or setting the pump. These units are effective for handling steel, PVC, and polyethylene drop pipe, pump, and wire between 500 pounds to more than 1000 pounds.

In many cases, these devices provide the most practical and safest method of pulling externally scaled pipe or several hundred feet of polyethylene pipe and pump from a well. There are various makes and models with specific weight limits and options, such as remote control and battery powered. Examples of two models are illustrated in Figure 8.

The Evolution of Electric Vehicles

The rapid rise and evolution of electric vehicles is sure to make a substantial difference in the water well industry over the next 50 years. Largely due to the wide variation in fuel prices and the perceived or real impact of climate change, one of the major changes has been a recent shift away from the use of internal combustion engines towards electric vehicles.

This technology is still in its infancy as far as large trucks are concerned, but the change shows promise, and every indication is this trend will continue.

Initially, electric vehicles were mainly limited to passenger vehicles, but improved battery technology has seen an increased presence of electric pickups and trucks. Virtually all the major automotive manufacturers including Ford, GMC, Toyota, and Chrysler (RAM) as well as Tesla have or intend to introduce a line of electric-driven pickups.

Larger trucks are also being developed that will enable mounting lighter drill rigs and pump hoists to electric-powered truck cabs and chassis. An example of this is the Zeus 9000-pound payload Z-19 chassis 800-volt system (Figure 9).

______________________________________________

This concludes this month’s edition of Engineering Your Business. We will continue this series looking back on 50 years of growth and change in the water well industry next month with an overview on test and water level meters.

Until then, work safe and smart.

---

Ed Butts, PE, CPI, is the chief engineer at 4B Engineering & Consulting, Salem, Oregon. He has more than 40 years of experience in the water well business, specializing in engineering and business management. He can be reached at epbpe@juno.com.