Controlling the Airspace
Compaction, ADC, and volume measurement are the keys to landfill profitability.
Landfill operators have to be diligent in their tracking of airspace utilization. This is because landfills basically sell thin air, and their profitability depends directly on how much waste they can pack into a given volume of disposal space. But operators will have no idea how well they are using airspace resources unless they can effectively track the volume consumed in a given time frame compared with the weight of the waste received during the same period. This information allows for direct comparisons with past operating practices at the site and with industry averages as a whole. This article will examine these three main airspace utilization and maximization techniques and how they affect a landfill’s bottom line.
Capital and Operating Costs
Capital costs at a landfill include the entire onsite infrastructure necessary for waste disposal operation, equipment maintenance, office management, and environmental protection. The largest single capital expenditure is the landfill itself. Depending on many factors, such as the depth of excavation needed to establish the floor grades of the liner system, the type of local soils and the difficulty of excavation itself, or the current cost of geosynthetics and consultant fees, the cost of constructing a single acre of landfill liner and leachate system suitable for receiving waste can run between $300,000 to $800,000.
Additional capital costs are associated with such onsite facilities and buildings as offices, machine shops, garages, fuel tanks, fencing, scales, scale houses, wheel washes, and access roads. These support facilities can cost between $1 million to $2 million. In addition to those facilities needed to operate the site, there are capital costs associated with closure of the landfill.
The final cap and cover, surface water management, and landfill gas extraction systems can together cost between $250,000 to $350,000 per acre. A 100-acre landfill could cost between $60 million to $120 million to construct and close.
Counterbalancing this on the ledger are the operational revenues gained from waste disposal. Let’s assume that a site’s limits of waste disposal are 100 acres in extent, approximately 2,000 feet by 2,000 feet. Because of local height restrictions, its maximum height above existing grades with 25% slopes is 100 feet (400 feet horizontal distance), creating a plateau of 33 acres (1,200 feet by 1,200 feet). Local hydrological conditions limit the average depth below existing grades to 50 feet with 33% side slopes (150 feet horizontal distance), creating a liner floor of 66 acres (1,700 feet by 1,700 feet). This results in a total volume of approximately 10,800 acre-feet (6,650 acre-feet above grade and 4,150 acre-feet below grade), or 17.4 million cubic yards.
With proper compaction, this volume could be equivalent to a waste mass of 9.4 million tons. At an assumed waste receipt rate of 1,000 tons per day, the landfill would have an operational lifetime of 36 years. The average annual capital costs would range from $1.7 million to $3.3 million dollars, though this will vary widely with some years having no capital costs while other may involve the construction of a complete disposal cell up to 10 acres in extent. With a typical tipping fee of $30 dollars per ton, the landfill’s gross earnings would be as high as $7.8 million annually.
The operating costs involved with the actual disposal of each ton of waste are actually quite small compared with capital costs for site construction. Direct operating costs may run between 10% to 15% of the tipping fee and include equipment operations and fuel, staffing, general maintenance, leachate collection and disposal, environmental sampling and monitoring, engineering service, and general overhead. Assuming high operating costs of about 15%, the above gross revenues can be reduced to $6.6 million net income.
The above is something of an extreme example, with everything going right and with exaggerations made to make a point. That point being how dependant a landfill’s profitability is on maximizing compaction and properly managing airspace. Improper compaction could reduce this landfill’s profitability to nil. Unlike capital costs associated with building and facility construction or liner and cap systems mandated by state regulations, the operator has the ability to affect his airspace utilization...and a landfill operator, like any other businessman is in business to make money.
Matching Your Equipment to the Characteristics of Waste
Landfills are sized by the amount of waste they receive. Small landfills receive up to 500 tons per day, moderate landfills between 500 and 1,000 tpd, and large landfills over 1,000 tons tpd. Typically, waste arrives at the landfill with a density between 15 and 25 pounds per cubic foot (an average of 20 pounds per cubic foot or 0.27 tons per cubic yard). Therefore, an assumed waste receipt of 1,000 tons would occupy an uncompacted volume of over 3,700 cubic yards, roughly equivalent 2.3 acre-feet, each day. The waste is deposited on the current workface and spread into a loose lift of 2- to 3- foot thickness. It is then compacted to half its initial thickness, doubling its in-place density to 0.54 ton per cubic yard.
MSW is a highly heterogeneous mixture of organic and inorganic waste items. Organic materials include paper and paper products (34%), yard trimmings when not composted (13%), and food scraps and byproducts (12%) for a total by weight of approximately 59%. Inorganic portions of the wastestream include plastics (12%), metals (8%), textiles including cloth leather and rubber (7%), glass (5%), wood and furniture (6%), and all other (3%) for total inorganic portion by weight of 41%. So there is a rough 60/40 split in most municipal solid waste between organic and inorganic waste. These characteristics affect the waste’s initial density, void volumes, compaction potential and long-term decomposition volume—all of which affects airspace management requirements.
Given the quantities and characteristics of incoming waste, what type of equipment fleet should a landfill operator use to effectively manage his landfill’s wastestream? Standards have been established in the Caterpillar Performance Manual’s section on waste and landfill handling equipment. There are several functions that landfill equipment is required to perform that affect the choice of the landfill equipment. These functions include waste handling, cover material application, and general operational support (from the Caterpillar Performance Handbook, edition 41):
- Waste handling and compaction equipment dispose of the waste. Track-type tractors, track loaders, and landfill compactors are the primary machines.
- Cover material–handling machines provide daily cover requirements. If supplying cover material is a machine’s sole function at a landfill, it can be selected on the basis of normal earthmoving considerations, such as material characteristics, distance to borrow areas, volume to be transported, and other basic earthmoving principles (i.e., maximizing earth movement in the least amount of time at the lowest cost per yard).
- Support equipment includes motor graders, backhoe loaders, hydraulic excavators, water trucks, air compressors, service vehicles, water pumps, generators, and any other necessary equipment.
The specific types of machines required for each task are further dependent on a series of operational and financial factors:
- Amount and type of waste to be handled (daily tonnage)
- Amount and type of soil cover to be
- Distance cover material to be transported
- Weather conditions
- Compaction requirements
- Landfill method utilized
- Supplemental tasks
Generally speaking, the greater the amount of waste received each workday, the larger and more numerous the waste compaction equipment required. For example, a site receiving less than 500 tpd would require a lighter-weight model Cat 816F2 waste compactor (operational weight of 52,364 pounds), while a site that received up to 750 tpd would use a heavier model Cat 826H (81,498 pounds), and a site receiving more than 1,000 tpd would require the heaviest model Cat 836H (118,348 pounds). Similar matching increases in size for such support equipment as dozers and tracked front-end loaders would also be required for each landfill size.
Al-Jon produces a series of waste compactors under the Advantage label, ranging from the relatively lightweight Advantage 500, to the heavier Advantage 525 and to the Advantage 600, the heaviest waste compactor in North America. The 500 weighs in at 82,000 to 88,000 pounds with 48-inch-wide wheels equipped with 8-inch-long cleats, and can use a full-U, semi-U, or straight blade. It uses either a Cat 15.2-liter engine with 475 horsepower or a John Deere 13.5-liter, 500-horsepower engine. The 525 comes equipped with extra-heavy-duty steel construction and a sealed undercarriage, producing a compactor perfectly suited for use in rugged landfill conditions. Equipped with similar blades and wheels as the 500, the 525 is powered by either a Cat 15.2-liter engine with 540 horsepower or a John Deere 13.5-liter, 550-horsepower engine. Finally, the 600, which weighs 126,000 pounds, utilizes an all-wheel hydrostatic drive that does not need a torque converter, clutch, differentials, or axle shaft. As befitting its larger size, the 600 has 55-inch wheels and 10-inch cleats. It is a unique combination of sophisticated drive and pure brute force suitable for the largest landfills.
With an operating weight of 81,000 pounds and a 442-horsepower diesel engine, Bomag’s BC772RB is the leader of its line of waste compactors. This powerful engine is environmentally friendly, having been redesigned and retrofitted to comply with up-to-date Tier 2 emissions standards. In the heavyweight class is its BC1172RB, weighing 120,000 pounds and powered by a 511-horsepower diesel engine. Though heavy, it is surprisingly quick, capable of reaching operating speeds of 7 mph. Though designed for power, Bomag’s waste compactors have not neglected the creature comforts of operators working in a harsh landfill environment. Each comes standard with dust protection provided by a fully sealed and enclosed cab frame. Agility is provided by oscillating joints that allow for delivery of maximum pressure, even on slopes as steep as 30 degrees (a grade of almost 60%), and a hydrostatic power train that maximizes torque and coordinates the operations of all four wheels through an intricate circuit system.
Though not a manufacturer of compaction equipment, Caron Compactor is a major supplier of compactor wheels and teeth, as well as trashblades and crawler/loader track shoes.
The company pioneered the use of compaction wheels featuring high-alloy, field-replaceable, patented pin-on wheel cleats, designing wheels and cleats with increased density as a primary objective. By plugging in site-specific information, Caron’s Compaction Efficiency Calculator, found at http://www.caroncompactor.com, provides a complete analysis of increased density impact on profitability.
Caron wheels come in two basic configurations: standard-width wheels to match the original manufacturers, and narrower, high-density wheels for increased pounds per linear inch. The Megamax Maximizer teeth are made of durable material guaranteeing a limited 10,000-hour warranty on the replaceable caps (equivalent to almost 3.5 years of typical landfill operations). The Wire Safeguard Group, with a continuous leading edge, helps eliminate wrapping without sacrificing overall wear life. In addition to wheels, Caron produces semi-U and double-semi-U trashblades for compactors and crawler tractors, as well as producing track shoes for solid waste applications. The company maintains a wheel and trashblade rebuild center in Chicago.
Caterpillar Inc. manufactures a series of purpose-built waste compactors, the 816F2, the 826H, and the 836H. The lightest of the three, the 816F2 weighs in at 52,364 pounds with a 253-horsepower engine. The heavier 826H and 836H have operating weights of 81,498 pounds and 122,586 pounds respectively with matching 401-horsepower and 555-horsepower engines (gross horsepower). However, there have been some significant changes lately to the heavy-duty 836H.
The 836H’s basic design has been continually refined, including a recent design update that makes this machine even more productive, easier to operate, and easier to service. A new auto-idle kickdown (AIK) system boosts fuel economy by automatically reducing engine speed when the 836H has not actively operated for a set time interval. The interval can be adjusted (from five to 60 seconds) through the Cat Electronic Technician, and the operator can enable or disable the system via a switch in the cab. Complementing the AIK feature is a new Idle Shutdown system, which automatically stops the engine after it has idled in a safe state for an extended time. The safe-idle interval is adjustable (between three and 60 minutes), and the system visually and audibly alerts the operator before engine shutdown, allowing time for manual override. Blade performance is enhanced for the 836H by a regeneration (“regen”) valve that assures positive hydraulic flow to the blade lift cylinder. This closed-loop hydraulic circuit reduces the potential for drawing a void on the head side of the lift cylinder as the blade lowers, thus keeping positive down-force on the blade and preventing it from being forced up by debris. Overall, the new system improves blade response and controllability.
The design of the new belly guard for the 836H is significantly refined, including wear plates made from more abrasion-resistant material, structural changes that provide a fourfold increase for withstanding impact forces, and labyrinth joints that reduce debris entry. The new guard incorporates a smooth profile that eliminates catch points that can cause wear and access issues to the belly guard. Along with this new bottom design are four hinged access doors that can be hydraulically actuated, allowing for easier access on both front and rear structures. Other structural enhancements include protected internal hinges, relocated mounting bolts (now protected from abrasion), and a design that better protects the center axle housing, rear trunnions, and hitch. The belly guard now can be serviced by one technician (not two) and has improved access minimizing service cost and downtime. Complementing the new belly-guard design is a 2-inch (51-mm) increase in the diameter of the 836H’s wheels, resulting in a 1-inch (25-mm) gain in ground clearance, to 25 inches (635 mm). Greater ground clearance reduces the resistance and abrasion caused by debris sliding against the belly guard, which provides a system approach for more productivity and greater traction and wear life on the Cat Stepped Tips.
HJ Industries is a manufacturer and distributor of customized products for the waste industry, including the highly rated Trac-Pac Compaction wheels for a wide variety of makes and models (Caterpillar, Bomag, Aljon, and Terex) and the patent-awarded HJ Final Drive Seal Protection Guard for the Cat Dozer Series. HJ Compaction Wheels are equipped with HJ’s patented Trac-Pac Compaction Cleats. Trac-Pac cleats and wheels are designed for use on compactors up to 120,000 pounds operating weight working in a variety of applications, including MSW, C&D, and sloping. The exclusive dual-traction pocket feature ensures that the cleats wear sharp, do not round off, and maintain superior traction throughout the wheel/cleat life cycle. The latest addition to the HJ product line for 2011 is the patent-pending Trac-Pac Waste Handler Compaction Track Pad for tracked dozers. HJ has created the first track pad in the industry to introduce compaction-like characteristics to the Cat track dozer equipment line. Features include increased grouser bar height (permitting higher compaction density), improved material size reduction, and extended track pad wear life.
Landfill Equipment is not a supplier of waste compacting equipment but is an industry leader in its rebuilding and reconditioning of previously owned equipment. Its final waste compaction equipment products are rated “work ready” for sale or rent. The company can refurbish, completely rebuild from frame up, or recondition any type of compactor on the market (including Caterpillar, CMI/Rex, and Al-Jon). The company also provides the same service for compactor machinery parts and waste compactor wheels and cleats. Not stopping at sales, Landfill Equipment’s service technicians and heavy-duty over-the-road service truck can provide onsite service for all makes and models of compactors.
Terex manufactures two models of waste compactors, the Terex TC400 and Terex TC550 Trashmaster. Both models offer a unique triangular wheel configuration, which increases stability and delivers full-width, single-pass coverage. The balance between operating weight—80,000-plus pounds for the TC400 and 110,000-plus pounds for the TC550—and wheel design deliver class-leading PLI compaction force. Offering 606 PLI and 733 PLI respectively, the TC400 and TC550 are able to compact more refuse in the same amount of space, increasing densities. With a contoured design that enhances wheel shredding action, the self-cleaning “Big Dog” cleats found on Terex compactors reduce refuse size and surface “fluffing.” With its 36-inch rear-wheel and 30-inch front-wheel widths, the TC400 offers 11-foot full-width wheel coverage. The TC550 delivers 12.5-foot wheel coverage with wheel widths of 35 inches in the front and 40 inches in the rear.
Terra Compactor Wheel manufactures compaction wheels, not the entire compactor. Its wheels can be found on the equipment of all the major waste compactor companies. An innovator in the field, Terra has developed a left- and right-hand twist-torque design for its compaction teeth.
The torque action of the cleats directs the flow of waste under the wheels while using wheel turning and rolling force to positive effect. The teeth patterns are designed to pull waste from under the center of the machine to where it can be properly compacted during the forward motion of the machine’s compaction pass. The effect is to improve waste compaction efficiency while reducing inefficient spin.
Daily Cover Requirements
Not all the airspace taking up a landfill’s disposal volume is occupied by waste. A significant portion of this space is daily and intermediate cover. Depending on operation efficiency, somewhere between 5% and 20% of a landfill’s volume can be non-waste cover materials. In addition to being potentially loose and dusty, the decaying organic portion of municipal solid waste can give off noxious odors while attracting potentially disease-carrying vectors (e.g., insects, birds, rodents). Daily cover is therefore required by solid waste regulations and is intended as a means of controlling odors, minimizing blown dust and debris, preventing the breeding of insect swarms, and to prevent vermin and birds from accessing the waste mass.
Most regulations call for the application of a layer of at least 6 inches of cover soil over the exposed current workface at the end of each workday. Similar to daily cover, intermediate cover soil layers of 12-inch thickness are typically applied to those waste surfaces that may be exposed for extended periods of time (usually 30 days or longer).
Assuming again a moderate to large landfill that receives 1,000 tons per day of waste, that waste would be ideally compacted in-place to an average density of almost 0.5 ton per cubic yard. If placed in only one layer, the compacted waste would cover a surface of 54,000 square feet (2,000 cubic yards, or 54,000 cubic feet at a thickness of 1 foot), almost 1.25 acres. Most workfaces are smaller than that, 0.5 acre or less being common, to minimize waste exposure and the potential for windblown dust and debris and to allow a landfill to operate effectively with a smaller equipment fleet.
Further assuming a workface of a quarter acre (about 100 feet by 100 feet), a properly compacted daily waste receipt would form a layer with a thickness of almost 5.5 feet. The application of a daily cover soil layer of 6 inches of dirt would therefore increase the overall daily lift thickness to 6 feet. Under this scenario, daily cover soil would constitute over 8% of the total airspace volume. Given that this volume could ideally be filled with solid waste, the use of daily cover soil would reduce potential landfill gross revenues by that same 8%.
But soil is not the only possible daily cover material. There are broadly speaking, five other types of alternate daily cover that can be used instead of soil:
- Disposable sheets of thin plastic film
- Reusable tarps or sheets made from high-density polyethylene (HDPE)
- Reusable tarps made from heavy geotextile
- Spray applications using inorganic chemicals and concrete
- Spray applications that utilize such organic materials as pulped paper
Thin plastic films, polyethylene tarps, and geotextiles are relatively easy to deploy in calm weather by means of unrolling the sheets from a roll attached to a spreader arm fixed to a dozer or other piece of landfill equipment. However, they can be difficult to deploy in high winds. Plastic films are the least expensive in terms of cost per square foot, but HDPE and geotextile tarps can usually be reused multiple times until they are too worn to function properly. If left in place, sheets and tarps have to be purposely torn and shredded by running equipment over them prior to the next application of waste. This is done to prevent the impermeable sheets from forming pockets of perched leachate, which can leak out of a landfill hillside and/or cause slope instability.
Spray applications require specialized application equipment (mobile high-pressure hoses and spray guns). These covers can also be difficult to deeply in high winds and can often clog if used during freezing weather. The spray applications dry, forming a crusty surface that can be broken up by track walking with equipment at the start of the next workday. The materials utilized will either physically disintegrate or biologically decompose so as to not take up any disposal volume.
In either case, alternative daily cover (ADC), whether traps or sprays, can significantly increase the airspace utilization rate of a landfill and with it the landfill’s gross revenues. Taking the scenario described above, an ADC used in place of soil cover would free up nearly 8% of the of the landfill’s overall airspace volume, volume that could then be utilized for additional waste disposal. Using the hypothetical landfill described above, this facility would have a gross disposal volume of 17.4 million cubic yards.
Without in-place compaction, this airspace volume would be equivalent to approximately 4.7 million tons. At an assumed typical typing fee of $30 per ton of waste received, the minimum gross value of this landfill would be $141 million. However, effective compaction would double the density of the in-place waste, increasing the landfill’s gross value to $282 million gross. But the use of soil cover would eliminate 8% of this disposal revenue, an operating loss of approximately $23 million. It is easy to see why waste compaction and ADC easily pay for themselves.
|Photo: HJ Industries
HJ Industry’s Trac-Pac cleats and wheels are designed for use on compactors up to 120,000 pounds operating weight working in a variety of applications.
Airspace Saver Daily Cover is a reusable tarp produced by Sassco Supply. Fabrene Inc. manufactures the fabric used to make the tarp. The lightweight but high-quality tarp material is further strengthened by high-strength (6,000 pounds yield strength) polyester web straps sewn into every seam and around the hem of the tarp sheet. At intervals of 12 feet around the hem, the tarp is equipped with steel D-rings that allow men and equipment to securely fasten and place the tarp. If rugged durability is a requirement (and it typically is for landfill applications) additional reinforcement can be added with a heavy cable or chain sewn into the hem. The chain adds additional weight to the tarp, which steadies it and allows for easy placement even in high winds.
AmCon Environmental Inc. is a manufacturer of woven polypropylene ADC tarps. The tarps are woven to reduce air infiltration into the landfill and shed precipitation off of the workface. Designed for rugged landfill applications, the tarps can last up to a year of application and can even be used as a foundation for temporary landfill access roadways. Reinforced by 15,000-pound tensile strength nylon webbing sewn into the edges and corners, the 8-ounces-per-square-yard fabric can be easily deployed without damage.
EPI Environmental Products Inc. manufactures the Enviro Cover System (ECS) a degradable polyethylene film primarily used as an ADC in landfills. Enviro Cover occupies almost zero volume while meeting the Environmental Protection Agency’s requirement (40CFR258.21 3.3.1(b)) of ADC “to control disease vectors, fires, odors, blowing litter, and scavenging without presenting a threat to human health and the environment,” saving airspace and reducing operating costs. Enviro Cover is not an ordinary plastic film. It possesses extremely good resistance to puncture and tear, as well as elongation properties, and it has been specifically designed to meet the requirements for daily and intermediate covers. With EPI’s patented pro-degradant additive, Enviro Cover is degradable under the thermal, mechanical stress, and/or photo conditions of landfills. This degradation capability ensures that Enviro Cover will not affect the vertical movement of landfill gas and leachate within the waste mass. The operational benefits of using this product are manifold: increased landfill capacity by 15% to 50% by conserving airspace; reduced costs of importing, moving and placing earthen cover material; rapid coverage of the workface; and no removal costs. There is no need for removal, since the film acts as a “blanket” barrier and, in time, will lose tensile properties and degrade.
The degradation process is thermal in nature. Biodegradation of waste produces heat, carbon dioxide, methane, water, and biomass. As a result of the heat of biodegradation, the temperature inside a landfill is usually higher, and may be up to 35°C and higher than the ambient air temperature in deep landfills. This high temperature is a resource to break down thermally degradable polyethylene ADC films within a landfill. The Enviro Cover is a thermally degradable film. It contains EPI’s patented pro-degradant additive that enables the film to undergo thermo-oxidative degradation at elevated temperatures. Following thermal degradation, the remaining molecular fragments may be subject to anaerobic biodegradation and are eventually reduced to form methane.
Deployment is performed with EPI’s specially designed equipment. The company’s model 610 is designed for small to midsize landfills. This is an attachment that can be easily fixed to a standard front-end loader bucket. It is capable of deploying a 10-foot-wide roll even in extreme weather conditions. Its ballast is held in the bucket itself and is poured out on top of the film as it is being deployed. The Model 628 is designed for larger landfills and can deploy a 16-foot-wide roll. It can be attached to a dozer blade and comes with a hydraulic dispensing system that allows for reliable and consistent distribution of ballast (anchoring) material (which can be almost any material smaller than 4 inches in diameter).
Kym Industries Inc. is in the container liner and area tarp business. The company’s tarp products are constructed from heavy-duty but lightweight polypropylene material a minimum 19 mils thick and weighing from 10 ounces to 22 ounces per square yard. They come equipped with reinforced webbing around the hems, vinyl reinforced pockets, double stitching, grommets at regular intervals around the perimeter, and secured loops for transporting and placement. The tarps can be manufactured to local specifications and conditions using a wide variety of material and additives, including fire retardants and UV inhibitors. The tarps can be made to any size specification.
Not every alternate daily cover material is a reusable tarp or throwaway sheet. Landfill Service Corp. manufactures Posi-Shell cover systems, a spray-applied mineral mortar coating, similar to stucco. Posi-Shell cover is both inflammable and durable over long-term exposure. It consists of a liquid base (water or leachate) mixed with Posi-Pak P-100 fibers, and a PSM-200 setting agent. Even latex paint can be added to the mix (if local regulations allow), further enhancing its durability. Durability and multiple colors can be altered by the addition of Portland Cement and dyes. The final product forms a durable, nonflammable crust that resists wind and water erosion. Different formulas can be mixed using ingredients in differencing proportions to create different applications (short-term overnight cover, intermediate cover for erosion and odor control, and long-term cover for stockpiles and compost). Since the crust (though resistant to wind and rain) can be easily broken up by simple track walking with equipment at the start of the next workday, it will not interfere with gas or leachate migration through the landfill.
Southwestern Sales Co. manufactures a highly efficient automated tarp deployment system. Combining the patent-pending tarpLOX-equipped tarpARMOR tarps with the company’s labor-efficient TDS tarp deployment system, one operator can lay up to 12,000 square feet of tarp in fewer than 10 minutes from the comfort of the cab of existing landfill equipment.
The tarpLOX system provides complete coverage every time and will not allow tarps to bunch together in the middle of the spool and reduce the tarp’s coverage area. Its two-tarp deployment systems, the TDS-30 and the TDS-30 HC, can deploy up to four ballasted tarps (each measuring 30 feet by 100 feet). The smaller model, the TDS-30, deploys three 6.5-ounce-per-square-yard tarps, weighs in at 3,000 pounds, and is applicable for landfills that have a high sludge content, muddy conditions, or otherwise require the use of low ground pressure vehicles. Made with a frame of heavy-duty steel, it has wide foot pads directly welded to the frame. The heavier TDS-30 HC weighs 4,000 pounds and can deploy up to four tarps, each at 9.4-ounces per square yard.
New Waste Concepts provides one-stop shopping for almost all of a landfill’s safety and aesthetic needs (daily, intermediate, and long-term covers as well as cover additives, seeding stimulants, odor controls, bird controls, and dust controls). The company’s non-cement, spray-on ADC can be applied with specially designed spray equipment. New Waste Concepts’s Topguard is a blend of polymers and recycled fibers that needs no further additives or mixing. Proguard SB is a higher-density version with higher viscosity, suitable for steeper slopes and adverse operating conditions. Proguard IIB and IIB+ are designed to adhere more effectively to a workface. For intermediate and long term covers, their ConCover SW can provide cover for up to 60 days.
Tarpomatic’s Automatic Tarping Machine (ATM) is a self-contained unit that attaches to heavy equipment to unroll and retrieve different types of fabric panels. Using this device, tarps can be deployed in all weather conditions, including winds of up to 70 mph. The remote system has automatic shutdown and remote motor startup. Each ATM is custom-fitted to be lifted and transported by dozer blade or related equipment. The ATM uses a hydraulic drive motor and engaging system to unwind and rewind the tarp spool with variable speed control. Spools can be disconnected and reconnected, using a single ATM to link a series of tarps together to cover or uncover a landfill’s workface. The operator can control the ATM’s engine, height of the spool, and forward or reverse rolling through a controller unit placed in the cab. The system is designed for 40-foot-wide panels of various lengths and can be adapted to a wide range of heavy equipment.
ATM operation procedures are relatively simple: Drive the ATM to the top of the workface with a full tarp spool in place. Deploy the tarp by activating the hydraulic drive and simultaneously backing your equipment until the workface is covered. Removing a tarp is also simple: Hook the tarp to the ATM spool. Activate the hydraulic drive and move forward to roll the tarp onto the spool. It is the fastest way to deploy landfill cover currently on the market.
Keeping Tabs on Airspace
Traditionally, landfills would track airspace utilization by performing a ground survey of the current workface and disposal cell annually, or maybe quarterly. Modern machinery equipped with GPS can track surface elevation daily and in real time. Not only can an operator keep tabs on daily compaction efforts, but he also can track equipment utilization and operator efficiency in order to optimize his fleet operations. Though there will always be a need for a confirmatory ground survey for formal reporting, GPS guidance equipment can mostly eliminate the need for manual staking and measurement.
A running tabulation of daily airspace can be modeled and used as the basis for reports and updates like any other business metric. The volume figures are created by AutoCAD programs designed to directly receive and convert GPS data into mathematical, three-dimensional surfaces called TIN files. Since airspace utilization is the business metric for landfill operations, GPS tracking is now essential to remain profitable and competitive. Volumes can be compared with tonnages received during the same period to calculate in-place densities and with past practices during similar operation all period. Airspace utilization trends can be established that will allow for accurate business forecasting.
InSite Software has developed a family of related software programs designed to perform site layout and earthwork analyses, including volume estimates and grading. Takeoffs can be done from image files (e.g., PDF, TIF, JPG). Instant updates are available in real time. Its SiteWork software can be used to calculate earthwork volumes from cuts and fills, topsoil and surface stripping, strata quantities, subgrade materials, topsoil respread, areas, lengths, trench excavation, and backfill.
The data used can be from digitizer input or CAD import as spot elevations, contours, 3D sloping lines, or a database that combines all three types. With this data, SiteWork uses patented Delauney Triangulation to generated ground surfaces, strata boundaries or grading plans.
Trimble Geomatics and Engineering provides hardware and software applications for a wide variety of landfill and earthwork: Terramodel for CAD design module; Paydirt for calculating soil volumes and quantities; SiteWork for detailed analyses of site projects, allowing an operator to produce detailed reports on cut-and-fill volumes; and RoadWork for haul-and-fill quantities for road construction. The reports created by these analyses can be saved to an Excel file, allowing for the importation of this information into spreadsheets and construction bidding software.
Specific to landfill operations, Trimble’s environmental solutions cover all the needs that take place in every step of the waste management process. This includes TerramodelConstruction, which can be used for landfill design and waste-cell construction. The company’s product line provides complete positioning solutions and services, starting at the waste collection and transportation through recycling and disposal at modern sanitary landfills or waste-to-energy facilities. Trimble’s tools allow a landfill operator to minimize expenses and maximize resource efficiency.
Topcon Positioning manufactures a series of GPS guidance instruments. Properly installed, these instruments can be applied to landfill workface and earthwork construction operations for both fine and rough grading. Topcon’s series of HiPer receivers (HiPer II, Hiper Lite, Hiper GA, Hiper Pro, and Hiper L1) can be integrated into earthmoving equipment or operate as standalone receivers. They allow for static-control point surveying and kinematic data collection. Topcon’s Millimeter GPS allows earthwork equipment to grade surfaces according to a stakeless grading system. It can take a GPS rover and transform it into a super-precise measuring device that rivals a robotic total station.
Augmenting this capable hardware is a suite of earthwork design and surveying software packages. Sitemaster and Sitemaster Lite are integrated design, surface modeling and construction survey systems, which provides seamless integration for Topcon field equipment and 3DMC systems.
Pocket 3D is a simplified field application with an intuitive touchscreen interface that allows field personnel to quickly and easily check grades anywhere on the site with cut/fill information constantly displayed on the screen.
As anyone writing a feasibility study will tell you, nothing is always an option. Even if it is an undesirable option, doing nothing serves as useful baseline for evaluating all other approaches. But in the real, highly competitive world of landfill operations, doing nothing (like failure) is not an option.
The above landfill-operating examples provide a clear illustration of how much the landfill industry and waste disposal operations have changed since the so-called good old days. In today’s competitive economy, landfill operators have to squeeze every dollar out of every ton of waste that arrives at their sites.
Many of the direct costs are out of the operator’s control. Truck scales will cost what current market conditions ask for them. Land and building construction costs are primarily functions of local economies. Leachate disposal rates are determined by local communities, and diesel fuel prices by world economic conditions.
But airspace is the one thing of which a landfill operator can and must directly take charge. All other things being equal, how well an operator uses his available airspace will determine whether he stays profitable and competitive. MSW
Author's Bio: Daniel P. Duffy, PE, writes frequently on the topics of landfills and the environment.