Productivity to Burn
GNSS helps streamline efforts in waste-to-energy plant expansion.
Energy from Waste (EfW), the processing of municipal solid waste (MSW) into heat, electricity, and pellets generally known as refuse derived fuel, has proven beneficial both for its potential and its ability to divert waste from landfills. At Covanta’s Niagara Falls, New York facility, a plant expansion is allowing improvement on both fronts. A new boiler will increase the efficiency of incinerating more than 2,250 tons of MSW per day, while the rail-to-truck facility will serve as the focal point for unloading waste shipped in from metropolitan New York City. The upgrade/expansion has been in the works for some time, according to Greg Maziarz, survey manager and project engineer for Pinto Construction Services (PCS), the general contractor on the job.
“In late 2012, we started Phase 1 of the project — realignment of one of the main rail lines into the plant,” he said. “We had to install the new track line and, because the site was flat and wide open, saw it as a great opportunity for GNSS guided machine control systems as well as multiple receivers on the site. We actually used a GNSS equipped dozer to mark out boundaries — a real plus since getting wooden lath into the frozen ground would have been impossible.”
That effort was followed in the fall of 2014 by Phase 2: remediation of a larger parcel next to the first. It was similar in nature as well — locating any structures in the ground, removing them or filling them with concrete, and so on.
“During that remediation phase, we took this whole site down an average of two feet and removed any waste and slag we encountered,” said Steve Beahen, PCS’s project superintendent. “We demoed 11,000 feet of buried old track, cut the site down, hauled off 30,000 tons of contaminated soil and material (in addition to the 20,000 tons removed in Phase 1), and brought in about 50,000 tons of new 2-inch runner crush. Despite a late start, we more than made up for it by incorporating GNSS guided machines and equipment.”
Maziarz added that using GNSS technology at the Covanta site paid other dividends as well. “We were compensated on volume, so, using either the bucket of the excavator or a rover, we would position anything we dug up,” he said. “Using Topcon Pocket 3D, we were making informative maps in real time which we would then send off to the owner with supporting images. They had proof of our volumes, allowing us to backfill and move on.”
“Even though the expansion site is 15 acres, pounding and working around stakes would have been a nightmare given
the amount of activity on site.”
The Main Event
With the preliminary phases completed, PCS moved on to the major component of the project: capping the site with stone, installing drainage throughout, laying down five additional rail lines — each nearly 3,000 feet in length — creating massive pads for the unloading effort and erecting a new thawing structure.
“Covanta has also gone to great lengths to make certain that all storm water is collected and sent to a monitoring station where it will be verified as being safe before it exits to the city sewers,” said Maziarz. “So there is nearly 5 ½ miles of piping running beneath the concrete pads. We built the model for all the work being done — including that massive web of storm sewer — loaded that design into the excavators we have onsite running Topcon X-63 machine control and they just went to work doing the 4-inch under drain.”
“And almost all staking has been eliminated,” he said. “Even though the expansion site is 15 acres, pounding and working around stakes would have been a nightmare given the amount of activity on site.”
Accuracy On Track
Key GNSS-equipped machines used by PCS at the Covanta site included a John Deere 750J dozer with Topcon 3D-MC2, as well as Komatsu PC-400 and PC-138 excavators, and a Doosan DX-225 excavator — each running Topcon X-63 systems.
“We used the John Deere 750 to grade the entire site, including the track areas in which tolerances had to be within ½-inch,” said Beahen. “The accuracies were so solid, in fact, that the concrete crew came in right behind us, set their forms for the pad and put down rebar without needing any additional grade work done.”
Efficiencies were also enhanced in an area in which the massive concrete pad butts up against a blacktop area. PCS built their design model to indicate that transition and, by doing so, they were able to cut subgrade for both areas at the same time and put the stone down in the asphalt section. Once the concrete was poured, they simply stripped those forms and made a single pass through the adjacent section before putting the blacktop down.
Dealing With Change
PCS prides itself on its ability to quickly respond to its customers’ needs and that strength, enhanced by its GNSS capability, was evident in the construction of a settlement pond on the Covanta site. According to Beahen, a mid-stream change, which could have disrupted schedules was easily handled.
“The pond was originally designed to be constructed using topsoil,” he said. “But, after we excavated, the engineers decided to switch to a fabric and rip-rap construction instead. Obviously rip-rap is a bit harder to handle and definitely more of a challenge to grade. But Greg built the model for it and Dwayne Seiler, our operator, using the GNSS-equipped Doosan excavator and a grading bucket, did it in just a couple of days. That just really sums up how impactful the technology has been for us out here.”