Contractors Adapt GPS To Track Trencher Operations

Two Iowa underground construction contractors have teamed to establish a field tiling operation that has adapted global positioning system (GPS) technology to control grade of drainage “tile” they install in state corn and soybean cropland.

Tiling takes its name from clay tiles installed in farm fields to remove excess moisture and was introduced to the United States in the late 1830s. Today slotted HDPE pipe is used, rather than clay tiles.

Coddington Wampler, LLC is a joint venture of David Wampler, owner of Jackson Creek Enterprises, Allerton, IA, and Darrell Coddington, Coddington Inc., Corydon, IA.

Jackson Creek Enterprises has wide experience installing underground water, sewer, gas, power and communications lines using trenching, plowing and horizontal directional drilling (HDD). Jackson Creek was one of the first HDD contractors to employ directional drilling for environmental remediation projects and remains one of the few companies in the U.S. that continues to use directional drilling in this market. Coddington does excavation, dozer and concrete work, building demolition, hauling and tree trimming for public utilities.

“There are many reasons for tiling fields,” said David Wampler, Jackson Creek president. “Tiling controls erosion and the soil’s moisture content, allows workers to get in fields earlier in the spring for planting, and can increase yields of five percent or more.”

Tiling is less costly than buying five percent more land, even if it is available, Wampler added. There also are tax incentives that will pay for tiling over time.

Wampler said most tile installed in the area served by Coddington Wampler is slotted HDPE pipe from five to 12-inches in diameter with some three and four-inch pipe also used.

“In our area,” Wampler continued, “trenching is the most common method of installation with some installed with tile plows. However, plows limit the diameter of pipe that can be used, and we like to maintain cover at 40 inches to prevent the possibility of damage from deep tillage equipment.”

“Most contractors in the Coddington Wampler area maintain grade with lasers,” said Darrell Coddington, Coddington president.

“However,” he explained, “lasers have limitations. The laser beam must maintain line of sight with the digging boom. Accuracy diminishes over distance and if the laser is setup wrong. the installation will be wrong. Weather also can affect the laser’s performance.”

Coddington Wampler made the decision to go with a GPS system because of the benefits it offers and to set itself apart from competitors, said Coddington. It consists of an Intellislope system incorporating a patented slope sensor manufactured by Gradient and a Raven Slingshot computer modem with a wireless telephone chip mounted in the cab of the trencher.

“The system connects to the Iowa Department of Transportation CORS network that provides 600 real time position updates per minute,” explained Coddington. “These updates, combined with the ability to view 18 to 22 satellites at any given moment, provide unparalleled accuracy without having to set up a base station in the field. If satellite coverage is lost due to tree canopies next to a draw or fence row, the system’s slope sensor takes over and allows trenching to continue without losing accuracy.”

The system was designed to be used on tiling plows, but Coddington Wampler adapted it for a trencher by modifying the machine’s hydraulics and adding a proportional flow valve that would work on a closed loop system. Placement of the slope sensor is critical to the proper operation of the unit, Coddington added.

For its tiling operations, Coddington Wampler purchased a Vermeer T655 Commander 2 series track trencher with a 20-inch tail wheel or idler on a single chain. The bridge of the trencher is set up for digging in dirt and has a hydraulic cylinder that controls the slope of the crumber shoe.

“This configuration,” said Wampler “does a better job cleaning dirt from the trench. We set it up to dig 22 inches wide at depths to eight feet. Unable to find a commercially-made tile boot that would accommodate 12-inch tile, we designed and built our own. The trencher gives us greater flexibility and we are not limited to field tile only. We have used it to install storm water drains and with very little modification we can use it to install road drainage, electric, gas, water and other work.”

The machine is powered by a 250-horsepower diesel engine. Its rotary power head shaft motor and splined head shaft produce lower speeds and higher torque to maximize trenching performance and minimize wear on chain. Spoil is removed by a conveyor system.

There are no established drainage districts in areas where the company tiles and tile lines typically drain into a creek or a road grade ditch. Coddington Wampler also builds terrace structures to control erosion.

“Production in ‘good’ ground conditions is between 22 and 24 feet per minute,” Wampler said. “We did a job last spring where a three-man crew installed a little over 18,000 feet in three days. This included stringing the tile, installing tees, outlet pipes, rodent guards, back filling and all of the connections.”

To begin a run of tile, the crew tracks the trencher along the length of the planned path of the installation, mapping the route with GPS.

“After mapping,” explained Wampler, “we enter the parameters for minimum sloop and depth that we want to maintain, and the unit calculates whether it is possible to meet the parameters that we set. If it can, we flip a switch and start trenching. The machine operator controls the track speed and steering. The GPS unit controls the depth. Once we complete a tile run, we move the trencher to the next tile run and map the topography back to where we want that tile run to start and do the process again.”

The primary benefit of the system, said Wampler, is accuracy.

“The success of Coddington Wampler is the story of two contractors working together,” said Wampler. “Through the years, Darrell has hired me to drill for him and I have hired Darrell to do concrete work and haul for me. We borrow equipment from each other and have used each other’s employees from time to time. I really don’t think that Darrell or I either one would have jumped into the field tiling business by ourselves. However, going into it together made it pretty easy. We had enough experience with each other that we knew this would work. Darrell has some field tiling experience, and both of us are experienced sewer contractors.”

Coddington Wampler has no employees, but draws crews from personnel of Jackson Creek Enterprises and Coddington, Inc.

“Between us, we can shuffle our workforce and equipment enough to keep the tiling business going,” Wampler continued. “We never know who or how many are going to be on the tiling crew.”

Wampler said the original idea for the tiling business came from the desire of both companies to keep employees working in the off seasons.

“Neither of us has ever laid off our employees during the winter,” he said, “and the tiling business gives us something else to help keep everyone busy. In our area, the crops are usually planted in late April or early May and are harvested starting in late September through the first part of November. So we tile before planting or after harvest. Of course, we can be shut down by weather.”

The partnership has provided other benefits.

“Last spring,” Wampler said, “field tile was in very short supply and almost impossible to get. Darrell did business with vendors that I didn’t; I did business with vendors that Darrell didn’t; we both did business with some of the same vendors. By working all of the possibilities we were able to obtain enough materials to keep tiling.

“And employees like being assigned to the tiling crew. There are no traffic control issues, no irate property owners, no onsite engineers, no inspectors and seldom any existing utilities. They are out in the wide open country with nothing getting in their way.”

Jackson Creek Enterprises, (641) 873-6500,

CORS Ag Network

The CORS (continuously operating reference station) network used by Coddington Wampler is similar to agricultural RTK (real time Kinematic) systems. Both rely on RTK base stations to relay correction data providing sub-inch accuracy. However, there are differences in the two systems.

CORS network fixed RTK base stations are placed at intervals of 30 to 45 miles, compared to the six-mile grid typical of dedicated agricultural networks.

Where agricultural networks use 450-megahertz (MHz) or 900-MHz radios to relay correction signals directly from towers to RTK receivers, CORS networks use the Internet to carry correction signals to a cellular modem, cell phone or data card.

Agricultural networks are brand-specific, but CORS RTK is brand-neutral — with CORS networks, users may employ any brand RTK equipment, provided it is able to use standardized correction data formats provided by the CORS networks.

Related Articles