Sukut Construction Moves, Rebuilds Mountains

by Sheila L. Barger, CalContractor Magazine

Sukut Construction, Inc. is the industry’s leader at grading California’s steepest terrains in upscale and prominent cliff communities such as Crystal Cove and Pelican Hill Resort. However, available land – especially land with a coastal or mountain view – is becoming increasingly difficult to find. According to Sukut’s CEO, Mike Crawford, the easy ground is gone.

That’s why the award-winning earthmover is using new and innovative approaches to rebuild mountains, making this type of terrain a safer place to build communities. In fact, the use of GPS (Global Positioning System) technology for grade control is reinventing how a job is built.

Case in point: Standard Pacific Homes’ Three Oaks subdivision in Walnut, California. Sukut will move more than 17 million cubic yards of dirt to create 268 mountaintop lots for this multi-million dollar project that spans 268 grading acres. According to Michael Bobeczko, Director of Marketing, “The job started in May 2006 and by late 2007, there will be a mountain with a strong new foundation ready for development.”

He notes that utilizing equipment with GPS technology makes it possible to complete this project and to do so within budget and on time. This is yet another example of one of the company’s hallmarks: identifying key elements, foreseeing problems before they occur and creating solutions.

The earthmoving experts are now mountain-building experts. Michael Battaglia, Vice President of Project Development for Standard Pacific Homes, emphasizes that one of the main reason’s his company chose Sukut for this particular job is its track record for analyzing the problem, providing critical path planning, and utilizing state-of the- art equipment to solve problems. “This project has been on the drawing board for years and it takes great intuition and understanding to actually accomplish the rebuilding of a mountain’s foundation. Sukut has that experience,” says Battaglia.

Walnut Hills is the largest and most difficult job for Sukut’s Los Angeles office. Steve Yurosek, Los Angeles Division President, says, “The production of this job is massive, moving 1.5 million cubic yards each month in difficult, steep terrain. Thirty percent of the job is the construction of the four sheer keys, with over 300 ft. cuts and replacing them with up to 400 ft. deep compacted fill.”

During initial design stages, landslide areas were identified in the mountain. This required removal of landslide debris and weak clay layers as well as the construction of large shear keys within the foundation of the mountain. “A shear key is similar to the reinforcement of a buttress or footing to form the foundation’s support. It holds the weight of the mountain,” explains Harvey Davila, a Sukut foreman.

Davila notes that the steepness of the mountain grade prevents him from using a grade checker to obtain accurate measurements. “Sukut is pioneering the use of GPS technology to rebuild mountains, making it possible for machine operators to grade unreachable areas and to do so with a higher level of safety.”

Using an accurate 3D model of the terrain and GPS-equipped machinery, Sukut excavated the weak materials down to the bedrock. Many of the cuts excavated more than 1.5 million yards of earth. Sometimes, this involved digging past the bedrock to build a shear key large enough to support the excessive weight. Upon completion, 2 to 2.5 million cubic yards of dirt were replaced into the cuts. Between the layers, water was sprayed on the dirt and packed down by the Sukut’s equipment rolling over the new ground. This formed an average compaction rate of 93% of the maximum achievable density, making it almost as hard as rock.

Sukut has been using GPS technology for almost five years. Prior to GPS, the job was manually intensive, involving hand levels and grade checkers. Matt Eklund, Sukut’s GPS Program Manager explains, “Much of our grade checking is done digitally on a computer and then loaded onto the machine to keep the grade checker safely away from the equipment. Instead of being controlled by grade checkers moving amongst stakes, the operator can now simply pay attention to the screen to shape slopes.”

As developer, Standard Pacific Homes asked Jerry Pabbruwee, Sukut’s Vice President of Estimating, to review various options, risks and costs to maximize the area to be constructed. His investigation of the mountain’s footprint and the slide area confirmed the impact of pre-sheared weak clays within the foundation that would have major changes on the earthwork logistics.

It was determined that a sequential excavation/backfilling method would need to be used to complete all shear keys. A 3D model was drawn up of the site, identifying that four shear keys would need to be constructed. “An accurate 3D model can uncover potential problems in the design that can be mitigated before other project constraints are locked in,” explains Pabbruwee. “The model proves constructability of the site and is used later as the blueprint for layout and equipment control.”

Landslides are often initiated by subsurface ground water found throughout the mountain. Lowering the ground water and installing drainage throughout the project increases the stability of the slope. Todd Gunnell, Sukut’s Project Manager adds “There is 18 miles of sub-drain pipe and 10 miles of concrete “V” terrace ditches being poured to drain the water from the hillside. Along the entrance of the development, 7,200 square yards of Geogrid, or fabric soil reinforcement, will line the sloping areas for further stability. The total slope finish area is over 6 million sq. ft. or 145 acres.”

Mike Barnet, the onsite Sukut Superintendent, states that the biggest challenge is determining where to begin when slopes are steep and ravines drop 60 feet or more throughout the project. He indicates that using the GPS for complex designs and elevations has made it possible. “We are able to cut slopes, over excavate and finish pads at correct elevations. It would be nearly impossible to have a grade checker and surveyors complete this massive job in 18 months because of the harsh terrain.” He explains that, due to logistics, surveyors could not keep up with the productivity demands needed to meet deadlines.

The dozers and scrapers equipped with GPS no longer need surveying stakes to find the correct grade. The operators know exactly where to excavate and how to finish the slopes. Throughout the grading process, the grades are continuously checked. “The model that the operators see on their screen is checked against the engineer’s plan to make sure it conforms to the design,” continues Barnet.

Over 60 pieces of heavy equipment are developing the site, including Sukut’s newest addition to its extensive equipment fleet – the Cat 657G Wheel Tractor scraper and D9T Track Type tractor, both with Trimble’s latest GPS technology. After helping to complete the earthmoving, the GPS technology will be utilized in replanting the 50+ year-old trees that were removed before the project started.

“The GPS identified the location of dozens of oak trees growing on the site,” says Kevin Rhoades, Project Engineer, “After the construction is finished, we will replant them on the new foundation, returning the mountain to its natural beauty.”

Sukut Construction, Inc. is California’s largest mass excavation and grading contractor, moving 150 million cubic yards of earth each year. Founded almost 40 years ago and headquartered in Santa Ana, California, with offices in Oceanside, Los Angeles, and soon Riverside, the company is nationally recognized for its work on residential developments, golf courses, storm water drainage systems, landfill construction and environmental cleanups, landslide stabilization and heavy highway construction. In recent years, it’s garnered more than 30 industry honors, including the Contractor of the Year and Best Company to Work For.

Sukut is ranked the 224th largest contractor in the nation, amongst the nation’s Top 20 Storm and Floodwater Systems Contractors, and is the nation’s #1 Landfill and Environmental Cleanup Contractor, according to Engineering News Record Magazine. With more than 600 employees and 30 major projects, revenue projections total more than $250 million for 2006 making it one of California’s Top 50 Contractors. Additional information is available on the company’s website at www.sukut.com or by calling 800.339.6024.