Sustainable Land Development Today - October 2007 - (Page 23)

LAND SURVEYING GPS System Makes the Grade Irregular lake bed project offered great example of benefits with GPS technology. By Larry Trojak The Shadow Lake development in Papillion, Nebraska, is the latest addition to what is becoming one of the most prestigious — and fastest-growing — suburbs of Omaha. When complete, the 400-acre site will feature 700 mid- to upper-bracket homes and an amenity fairly uncommon to the Nebraska landscape: a 47-acre lake. However, that water feature alone offered its share of challenges. JAM Grading, Trucking & Demolition, the firm handling grading for the entire project, answered those challenges by equipping their excavator with a GPS system and turned a potential nightmare into just another normal day at the office. firm up enough for us to resume bringing in equipment,” Maloney explained. Lake depths, according to Maloney will vary, but will generally be 18-20 feet deep in the larger Shadow Lake reservoir side and 24 feet in the smaller Midlands reservoir side. “The Midlands side is designed deeper to allow for a 10-foot accumulation of silt from runoff over the next 20years. However, if the area continues to develop the way it has, the runoff won’t be anywhere near that projected depth.” Digging Sight Unseen With a 21-year history under its belt, site development is nothing new to JAM Grading. Even the opportunity to do some lake creation was well within its job description. Where things got murky (literally, in some cases) was in the special contours of the lake bed at Shadow Lake. “In many areas, the lake bed is anything but flat,” says Maloney. “It undulates with bowls, humps and ridges that are designed to be enticing habitats for fish when the lake is filled. While that’s a great, environmentally-sound idea, it presented a whole new set of grading challenges for us. Based on previous experience with this technology, I made the decision early on to purchase a GPS system; it proved to be one of the best decisions we could have made.” Despite their efforts to keep things dry, Maloney says there were many cases in which the lake bottom was still under water making it impossible to check grade in a traditional manner. “That was also the case with every one of the bowls and depressions in the lake bottom,” he says. “Using the Topcon 3DXi, however, our operator simply looked at the profile on his cab display and saw the whole picture: what he had done, what he was currently doing and what he had yet to do. Based on that, it was simply a matter of digging down to grade; a job which could have been a real headache was suddenly easy and accurate.” Hitting the Table The horseshoe-shaped feature at Shadow Lake is actually two separate digs — one 11-acres, the other 36-acres — which represents removal of about 400,000 yards of material. According to Jon Maloney, JAM Grading’s Project Superintendent, there were a number of issues that challenged them throughout the course of the project, but none more so than the water table. “Despite a hydrologist’s report that said it shouldn’t happen, water started coming in five feet before we hit our designated lake bottom. So we dug a trench to cut off the ground water, pumped out the area and let the ground Reliable Grade Control The system in place at JAM Grading, a 3DXi GPS+ system from Topcon Positioning Systems (Livermore, California), brings excavator operators the same grade control benefits available for years to users of dozers and scrapers. According to the Todd Bechtel, Vice President of Omaha-based DK&B Construction Specialties which initially rented the system to JAM, the 3DXi features 360-degree CAN-based tilt sensors which continually measure angles from the excavator’s cab, boom, stick, and bucket. “This allows the operator to make a precise cut every time regardless of what angle the machine is at,” explained Bechtel. “If he is sitting on a www.SLDTonline.com 23 http://www.SLDTonline.com

Table of Contents Feed for the Digital Edition of Sustainable Land Development Today - October 2007

Sustainable Land Development Today - October 2007 Contents Our Voice Your Voice Editorial Board Mapping the Development Process Looking at a New Dimension The Environmental Liability Continuum GPS System Makes the Grade Regulations: Reactions Mixed Trends: Communications Easements Business Management: Recycling Sustainable Practices: LEED-ND Energy: Community Propane Systems Transportation: Mountain Solutions Recommended Reading Calendar Products/Services Showcase Classifieds Advertiser Index The Last Word

Sustainable Land Development Today - October 2007

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