March 2015, Vol. 70, No. 3
Features
HDD Plays Major Role In Maintaining Florida Keys Ecosystem
It has been a long time coming for the Florida Keys, but the enormous undertaking of connecting all of the islands to central sewer lines to replace the use of septic tanks is nearly complete.
Septic tank seepage had been a concern to the fragile ecosystem of the Keys, and this new central sewer line alleviated that issue. Until its recent completion, the central sewer line installation had been in progress for over a decade, dating back to 1999.
The multi-faceted project required precise coordination and engineering by Texas-based Layne Christensen Company – a global solutions provider in the water, energy and mineral industries. The portion of the project in which Layne primarily focused was the Cudjoe Regional Wastewater Collection System for the Outer Islands, an area overseen by the Florida Keys Aqueduct Authority. JJD Contracting, of Deerfield Beach, FL, was responsible for the installation of several sections of the sewer line, including the section in the National Key Deer Refuge in Big Pine Key.
Previously, the Florida Keys relied on the use of cesspits and septic tanks for wastewater disposal. Research has determined that excessive nutrients are a primary contributor to water quality degradation in the Florida Keys, leading to depressed oxygen levels, an increase of algae and an imbalance in both the number and diversity of native aquatic life. The near-shore waters off the Keys were exceeding carrying capacity for nutrient pollutant loads from sewage and storm water discharges, effectively degrading the surrounding waters. In an effort to remedy the situation, in 1999 the Florida Legislature reinforced disposal requirements for all wastewater management facilities throughout Monroe County.
The Cudjoe Regional project, which began in spring of 2013, was the final segment of the Florida Keys central sewer line installation project, running 16 miles from Upper and Lower Sugarloaf Key through Cudjoe Key, Summerland Key, Ramrod Key, Little Torch Key and ending at Big Pine Key. Of all the Florida Keys, the Lower Keys would prove to be the most difficult section and also end up being the most costly of the multi-million dollar project.
In one section of the project, JJD Contracting was hired to install 6,500 feet of 4-inch pipe in the portion of land adjacent to U.S. Route 1 Overseas Highway, from Big Pine Key through the National Key Deer Refuge. JJD had three weeks to complete the Big Pine Key installation. Once in place, the sewer lines will rely on electric-powered grinder pumps to provide low pressure to maintain flow.
Pristine habitat
The National Key Deer Refuge is a large expanse of mostly undeveloped pinelands and provides critical habitat for hundreds of endemic and migratory species including 17 federally listed species like Key deer, lower Keys marsh rabbits and silver rice rats. Their range is limited to a small section of the Lower Keys with most of the population living on Big Pine Key.
In other sections, JJD Contracting was charged with the installation of 12-16-inch high-density polyethylene (HDPE) transmission pipelines, which presents its own challenges, particularly when it comes to selecting the proper boring equipment. According to JJD Contracting, a horizontal directional drill must have significant pullback and rotational torque performance needed to install the larger diameter pipe, all while having a small footprint to work in the confined area along the roadway.
While every job poses its own unique set of circumstances and challenges, underground boring throughout the National Key Deer Refuge created several obstacles of its own. To protect animals from being struck by ongoing traffic, a fence was constructed alongside U.S. Route 1, which created a tight working area for the JJD crew to drill. There also was a narrow strip of land that contained U.S. Route 1 and an adjacent tunnel, allowing the deer to travel between the two sections of the refuge. The intersect sits approximately 750 feet from each side near the entrance of the tunnel where JJD had to bore through the intersection to install the sewer line. This exercise was necessary due to the lack of clearance on the side of the tunnel.
Hard fit
The set-up for the job was a challenge in and of itself. A sloping ditch made it difficult to obtain the proper angle for the approach and there were varying substrate conditions, changing from rock, cobble, sand, crushed limestone infill and clay in short distances from one another. Facing a difficult task with a short deadline, JJD turned to their Toro DD4045 directional drill that they purchased in 2014 from Toro dealer Flagler Construction Equipment, Davie, FL.
“We’ve owned other drills before, but nothing compares to the power in the DD4045 for a machine of its size,” said Mike Gardiner, co-owner of JJD Contracting. “Cam-style pipe-loading allows it to maintain a more narrow operating width, which is just what we needed for working in tight spaces.”
Equipped with 52 pieces of 10-foot one-piece forged pipe for durability in a variety of conditions, the DD4045 is the largest directional drill offered by Toro. Dual outriggers with unique reverse provide maximum stability during pull back, and ultimately allowed JJD to get the right angle and better footing in the sloping ditch to drill. With a tight deadline, the DD4045 had all the drilling power the JJD crew needed with 40,000 pounds of best-in-class thrust and pullback, along with 4,500 foot-pounds of torque and drilling fluid pump infinitely variable at up to 70 gallons per minute.
“The rig was perfect for the site because it has the power for long bores, and for getting through changing ground conditions, all in a compact footprint for working in a narrow ditch alongside a busy road,” said Raymond Rodriguez, who has over 20 years of operating experience and has been with JJD for the past three years.
With the right equipment, the job went smoothly despite the challenges that JJD faced along the way, from tight areas to varying ground conditions.
While it was a big undertaking that spanned several years’ time, connecting the Florida Keys to a central sewer line was an extensive process, but one that was necessary and beneficial for both residents and the environment. It’s impossible to put a price tag on maintaining the fragile ecosystem of the Florida Keys, which provides a home to a myriad of beautiful creatures, and will continue to be enjoyed by millions of people for years to come.
FOR MORE INFORMATION:
JJD Contracting, (954) 570-8142
The Toro Company – Underground, (952) 888-8801, http://www.toro.com/en-us/underground/
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