DNT Construction photo
Now entering its 15th year in business, DNT Construction serves south central Texas customers in an area generally bordered by San Antonio, Austin and Houston.
As one of the larger civil construction firms in the Lone Star State, DNT Construction LLC is used to dealing with a range of challenges on its projects. As a result, the company has an equally full range of solutions ready to meet those challenges. Often, however, the impediment to production can be something as simple as a vein of hard rock, interrupting the normally smooth site prep effort.
Such was the case at a massive residential development in San Marcos, where a shelf of limestone running through the site added a step to the mass excavation/grading process.
Armed with hydraulic hammers — including an NPK GH-23 mounted on a Cat 349 — they showed the limestone to be little more than a temporary inconvenience. And all the rock being dealt with is effectively downsized and re-used on site. Big reductions, big efficiencies and big productivity. It's the Texas way.
One Stop Shop
Now entering its 15th year in business, DNT Construction serves south central Texas customers in an area generally bordered by San Antonio, Austin and Houston. With 750 employees, the company handles residential, commercial and municipal projects from excavation to utilities, and more. According to Hunter Drummond, a DNT vice president and equipment manager, that broad-scope capability has allowed them to grow into the company they are today.
"We consider ourselves a turnkey civil construction company," he said. "In addition to excavation, we do wet and dry utilities, retaining walls and, because this area is just exploding with growth, we have a large focus on residential subdivisions. The San Marcos area, in which one of our major, ongoing projects is located, is almost halfway between San Antonio and Austin, so the development around here is just through the roof."
The project to which Drummond refers, Kissing Tree, is a 1,300-acre, 55-year-old and up community which offers all of the amenities common to similar developments like The Villages, any Del Webb community, etc. DNT has been the site contractor on it for more than eight years and estimates that they are currently about halfway through the duration of the project. When complete, developers envision the gated community housing some 3,000 residences.
Sizeable Fleet
True to form, DNT's scope of work at Kissing Tree is extensive, tackling everything from site excavation to utility work to creation of retaining walls. The excavation/grading facet of the job includes pads for houses and community areas, as well as all new roads and sidewalks. Drummond said that their portion of the road work includes the subbase and base layer work — essentially everything up to asphalt.
"The utility work is quite extensive as well," he added. "We are doing all water, sewer, storm, fiber optics, gas, etc. It is in many of these areas that we encounter rock and need to turn to the hydraulic hammers. Our work over this last decade and a half has resulted in us putting together a pretty extensive fleet of 39 NPK hammers in addition to eight plate compactors — all of which we get from and have serviced by Waukesha Pearce, Inc.'s Pflugerville [Texas] branch."
The hammers in DNT's inventory vary in size from smaller PH-3's, used on mini-excavators to the GH-23 for 400 class excavators. As is common in the industry, the choice of hammer is dependent on a number of factors including volume and hardness of the material being encountered and a need to maintain a desired production rate.
China Syndrome
That last point — maintaining a specific production rate — came into play at Kissing Tree when a particularly hard seam of rock was encountered. According to Brad Dillon, one of DNT's excavation superintendents, it was challenging, even by Texas standards.
"The material we're encountering in one area, while still limestone, is much harder than we were anticipating," he said. "To give you an idea of how dense it is: if you pick up a pretty good-sized piece of it and drop it, it sounds like a China plate breaking — it's just nasty. I had two Cat 336s with GH-18 hammers working in that area and we were maxing out at 400 yards of material a day between two machines — well below what we were hoping to get. We knew we needed to take things up a notch."
Dillon and his managers called for a larger hammer, an NPK GH-23 mounted on a 105,000 lb. Cat 349 machine and, after arrival, saw immediate results.
"The single, bigger machine/hammer combo was bettering the production rate of the two smaller machines," he said. "Going with that larger hammer and machine not only got us better in line with our goals, it also freed up that pair of 336s to do other work on site. We are fortunate to have that kind of flexibility and make it work for us."
Hammer Time
If Drummond seems like he knows his way around a hydraulic hammer, it's because he does. Prior to coming to the contractor side, he was a service supervisor for a company that, at the time, was an authorized NPK dealer. That afforded him a much deeper knowledge of the hammers than most and allowed him to make an "apples-to-apples" comparison.
"While at that dealership, I had the opportunity to see and work on other brand hammers as well," he said. "Even back then it was obvious that the NPK hammers, particularly those in high production usage, were lasting probably twice as long as others between rebuilds. In addition, they're much more mechanic-friendly when it's time for that rebuild — there's no need for special stands or specialized tooling to get the work done. And their longevity speaks for itself; we've got quite a few in the 15-plus year-old range that we're still regularly using. In fact, we just recently finished rebuilding one that is 20 years old. While they're not the cheapest hammer to purchase, when you look at how long they will be in service, and the outstanding support they provide, they're really the logical choice."
Serious Commitment
The thousands of yards of rock DNT is hammering out at Kissing Tree will be used as fill in areas outside of the house pads — those in which material density isn't a factor. In addition, it can find use throughout the development as retaining wall material and could be crushed for use at a later date.
"Because this site is so massive, the earthmoving and grading effort is balanced, so there's no need to take material off site or — with the exception of specialized product — bring any on," said Dillon. "Being able to use the hammered rock plays into that scenario nicely."
Drummond added that an obvious partiality for one brand of hammer over any others is not unique to DNT, citing the fact that the two other largest contractors in that region also share their preference.
"Construction is a game of productivity, and you have to go with the tools that are going to serve you best, providing you with solid production and minimal downtime. We, along as the other big players in this market, have learned that NPK fits that bill. That's why, several years back, when our existing dealership took on another line of hammers and dropped NPK, we didn't change hammers, we changed dealers — the next day. We believed in it that strongly, and it's proven to have been the right choice every day since."
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