Why cover your rolloff containers, or any load for that matter, with tarps? The answer is simply “protection.”

By Daniel P. Duffy

Tarps protect the load from the elements. They also protect fellow motorists from objects thrown from loose loads. These common-sense requirements are codified into laws and regulations governing litter or roadway safety in every state. Those of North Carolina provide a good example: Loads must be securely covered by tarpaulin or other suitable covering to prevent them from falling, dropping, shifting, leaking, blowing, or otherwise escaping.

Many local businesses, such as landfills, also require that loads be tarped. Consider this example requirement for waste disposers at the Foothills Landfill in California: All loads must be properly tarped; a double disposal fee will be charged for loads not covered. And at a municipal solid waste transfer station in Illinois, a dedicated tarping and inspection station must be constructed near the location where transfer trailers exit the transfer station building. The tarping station must be an elevated structure that provides transfer trailer drivers with a convenient location to effectively and securely tarp their loads prior to departing the site. The tarping station must be constructed in accordance with all applicable OSHA requirements.

In this article, we’ll examine the uses of various types of tarps, their deployment mechanisms, specialized applications, the interface between the tarp and its rolloff box, descriptions of products from major tarp manufacturers, and descriptions of their use from hauling contractors.

Rolloff Boxes: Sizes, Shapes, and Uses
Rolloff boxes are used for the temporary onsite storage of waste, debris, contaminated soil, and tank cleanout byproducts. Those with rear door access are usually serviced with gasket seals and splashguards to allow for the containment of liquids from the waste. Their standard volume capacities vary among 18-, 20-, 25-, and 30-yard sizes. Though some come with integral lid configurations, most rely on deployable tarp systems for load covering, especially for loads piled higher than the sides of the rolloff boxes.

In all cases, the rolloff boxes are serviced by up to eight relatively small-diameter metal wheels installed along the bottom, as well as welded eyelets or rings for hooking the boxes to a wench. A typical box width is 102 inches, with lengths varying from 16 to 24 feet; the heights of the rolloff box sidewalls vary with the volume capacity of the box. Rolloff boxes can be equipped with vertical filters, providing a one-step method for separating and dewatering sludges, slurries, and wastestreams. Liquid drains through the installed filter media panels and out of the container via discharge ports. Lugger boxes are smaller versions of rolloff boxes varying in size from 3 to 20 cubic yards. Compactor containers are larger versions of rolloff boxes (20- to 50-cubic-yard capacity) designed and built to withstand compaction feeder operations and to contain higher-density waste material.

Tarping Systems: Covers and Mechanisms
So what distinguishes a “rolling tarp” from the traditional pullover tarp that is deployed manually and tied in place? A rolling tarp has a support structure consisting of a series of parallel bow-shaped frames. The ends of the bows are anchored to a series of rollers on either side of the truck frame. It’s these rollers that give the tarp system its name. The rollers slide up and back along a track mounted on the siderails of the rolloff box or truck bed. The movement of the cover can be controlled from the cab or the ground. The cover expands or contracts like an accordion. The bow-shaped frame allows the cover to easily clear the material in the load, reducing the chance for tear or abrasion. Once fully extended, the tarp is taut (to eliminate slack that can be caught by wind) and locked in place.

The height of the bows will depend on the load being covered. Loose, small particle loads (such as sands and aggregates) will pile relatively flat in the truck bed or rolloff. Larger objects (construction debris, stacked tires, etc.) will tend to pile high in an irregular fashion. Special items such as equipment, generators, crates, etc., will require specially fitted tarps. In addition to special fitting, tarps can be equipped with such special features as rear doors like those found on trailers, rigid bulkheads, or other sidewall kits. All such features must be securely locked in place to prevent wind damage during transport.

Manufacturers and Customers
Roll-Rite LLC
Roll-Rite provides four tarp cover product lines. Its Front-to-Back systems are used on straight trucks, trailers, and components for transfer tubs. The systems’ components (pivot arms and framing) are constructed of polished aluminum, which saves 40% in weight over comparable steel components. The pivot arms operate without a cylinder, resulting in less replacement and maintenance costs. The Front-to-Back system can be installed on trucks with a 102-inch width.

PHOTO: ROLL-RITE

Roll-Rite's adjustable system features offer more flexibility when tarping rolloff trucks or trailers that handle variable-sized containers.

Roll-Rite’s Light Truck system is designed for use on 1-ton and light-duty trucks. The system operation can either be semi-automatic (useful for infrequent tarping) or fully automatic (for frequent tarping). The semi-automatic systems are custom made and come pre-installed with a Roll-Rite tarp of appropriate size (up to 18 feet in length) and weight. The semi-automatic system does not use pleated or flapped tarps. Automatic systems are electrically powered and operated from within the cab. The automatic system uses tension or bow tarps only, and will accommodate pleated and flapped tarps.

For the waste industry, Roll-Rite provides tarp systems for rolloffs, hooklifts, and luggers. The system fits trucks up to 102 inches in width and is a lay-down variation of the company’s standard sliding pivot. Multiple options are available to create a custom system: electric-over-hydraulic or hydraulic power, optional towers and controls, and your choice of tarp fabrics.

Side-to-Side systems are available for general and sealed applications including side dumps, straight trucks, and long trailers for agriculture (bulk grains); paving and construction (aggregates); and solid waste (including debris). These systems can be operated either from within the cab or by remote control to allow the loader to monitor the tarping operation. Remote control is performed via wireless relays operated with a secure keyed lockout switch. The system also allows for the installation of direct-drive converter kits that replace manually cranked systems with electrically powered operations.

Roll-Rite’s customers can attest to its tarps’ versatility and ease of use: “I had another brand tarp system. … It didn’t work well at all. When I got my new truck and trailer, I asked my body distributor for the best tarp system. They showed me a Roll-Rite system they had installed on another truck. I could see the strong construction in the arms and system. I was very happy with the installation. The low profile [of the knuckle pivot] works really smooth and reduces the chance of catching on anything overhead. It’s just the best system on the market.” (R&R Excavating, Beaverton, MI)

Odin International, Thor Tarp Division
The Thor Tarp Division of Odin International provides a variety of tarps to protect hauled goods from wind, rain, snow, ice, and sun; from diesel smoke and salt; and from debris and other road damage. These include rolloff covers for construction dumpsters, railcar covers for moving loads, and stationary aggregate-loaded cars on the siding. The tarps also effectively contain loads of loose material such as gravel and protect other motorists from flying debris. This tarp will allow the hauler to meet state requirements for complete cover on loose loads.

Thor provides heavy-duty vinyl tarps for covering large, bulky, and uncrated equipment (such as generators, machinery, large steel structures, or construction equipment being hauled to a site). The ThoroShield 1850 and 2250 models are vinyl tarps coated with nylon to minimize wear, tear, and abrasion. These tarps can be custom sized and custom shaped, including a five-sided cover that snuggly fits over large crates. These crate-covering tarps are made from Thor’s DuraShield line of products. Tie-downs can be provided by D-rings, pipe loops, or grommets.

For large, irregular, and sharp-edged objects (such as debris being cleared and hauled from a construction site), the ThoroWeave 950 HMT or 700 MCM tarps are available. They are manufactured from a polypropylene tarp or vinyl-coated polyester mesh that contains debris while letting air through to relieve air pressure, which can cause a tarp to tear. Other specialty tarps are available for utilities (supply storage and clean rooms), construction (scaffolding covers and building enclosures), protection of telecommunications equipment (tarpaulins and rain drain kits), hazardous waste (containment of liquids and impacted soil stockpiles), and manufacturing (protecting rolling stock from rain damage and providing enclosures for temporary facility expansions).

Thor Tarp customers agree: “I would like to thank you for the tarp that Thor Tarp manufactured for me. It is exactly what I ordered with plenty of tie-down points and was built to precisely the measurements I requested. It fits my trailer like a glove. The material that the tarp is made out of is of outstanding quality and durability. I know this because the first time I used my new tarp I tied it down with some 1-inch-wide nylon motorcycle tie-downs, and the end of one of the straps came loose and went under the trailer tire while I was going down the freeway! The strap ripped in half without doing any damage to the tarp. Again, I am very impressed with the quality of your materials.” (Customer Charles Cain)

Dragon Products of the Modern Group (USA) Ltd.
Dragon offers a series of liquid-tight rolloffs with optional mounting tarp systems. The rolloffs are either slant-front open or heavy-duty, and are either open-top or closed-top containers. The closed-top containers are equipped with an over-/under-rolling lid instead of a tarp. The open-tarp containers (either slant-front or heavy-duty) with mounting tarp come in 20-, 25-, and 30-cubic-yard sizes. Gaskets constructed of extruded rubber seals reinforced by metal retainers provide the box’s liquid-tight seals. The cover is a full-opening side-rolling tarp with five bows constructed on a continuously welded box frame measuring 96 inches wide by 264 inches long.

K-PAC Equipment, a Division of Krause Co.
K-PAC manufactures a line of hooklift hoists, cable rolloff hoists, and container carriers. Its hooklift hoists vary from the KP806 12,000-pound-capacity dual pivot hooklift system to the Model 630 60,000-pound-capacity heavy-duty material loading systems. The hook hoist systems are designed with a full-length sub-frame, which fully supports the container during transit. Stability during transport is provided by eight different points on the sub-frame: four side rollers, two flange rollers, and two container guide support brackets. These supports remove the stress on pull hook assembly during transit, reducing the need for costly maintenance. The heavy-duty material loading systems come equipped with twin-acting hydraulic cylinders, and sliding “L-arms” that adjust for height and load distribution. Its 3,500-psi hydraulic system is backed up by dual counter-balance valves, which ensure safe loading even in the event of hydraulic hose failure.

PHOTO: K-PAC

K-PAC’s product line has a dedicated clientele, including Mike Adcott, owner of Waste Equipment Sales and Service LLC of Baltimore, MD: “Having been directly involved in the waste industry for over 20 years in both equipment sales and equipment service, I have seen products come and go. K-PAC makes what I believe to be the industry’s best tarping system! They have created a tarp system that simply outperforms all others on the market today. It’s the only system we stock because of its popularity. No serious waste hauler should accept anything less than a K-PAC tarp on their truck.”

Donovan Enterprises
Donovan manufactures six different types of tarp materials. The company’s knitted black mesh is a lightweight (only 6.5 ounces per square yard, less than half the weight of a polyvinyl chloride, or PVC, tarp), durable material. Its resistance to ripping makes it suitable for waste hauling applications. Donovan’s multicolor PVC mesh is used for standard applications. The vinyl tarp material provides waterproofing protection. The company’s asphalt lumite tarp provides a lighter-weight, waterproof cover. Where safety is a primary concern, Donovan’s orange dense web netting provides both increased strength and visual safety warning (this is the same material used for construction safety fences). The company also provides a mixed PVC/poly black mesh for applications where durability is a concern.

To deploy these tarps, Donovan provides its Hy-Tower tarping system. Hy-Tower is an armless tarping system capable of covering 20- to 30-cubic-yard rolloff containers. The roller rises 15 feet above the truck frame, allowing for easy covering of peaked loads. It is a simple-operation, low-cost alternative to standard arm deployment systems.

Aero Industries and Willow Marketing
Aero Industries Inc. has developed a hydraulic flip tarping mechanism exclusively for the refuse industry, the LID. Since it is hydraulically operated, the LID can be operated using the hydraulic system of the trailer itself. There is no additional cost associated with an independent tarp hydraulic system. Though it uses the truck’s hydraulic system, it is not operated from within the cab. The LID is opened and closed by an operator on the ground. Dave Boyd, Aero’s president, explains, “You simply push a lever on the hydraulic valve up to uncover the load and push the handle down to cover it again. It’s that simple.” The faster turnaround time increases productivity and efficiency, allowing operators to haul more per day.

PHOTO: AREO INDUSTRIES

The frame’s driveshaft design increases the LID’s strength to withstand high winds. This greatly increases the LID’s durability compared with ladder-style frames that flex and twist in motion. Additional features of the LID include front-mounted controls, low-profile front assembly, and internal support brackets. Mesh top covers are also provided to cover high peaked loads. The LID can be used on a wide variety of trucks (fitting a range of trailers from 43 to 53 feet long and 96 to 102 inches wide) and rolloffs. Since one size fits all, equipping a truck fleet becomes simple. The streamlined assembly uses half the hardware of comparable tarp systems—16 bolts and 13 welds. And hinge locations can be moved for a custom fit. The LID is one of three refuse products and among a dozen tarp systems manufactured by Aero Industries.

One of these is the Crank-N-Go tarping system, which allows tarp deployment without climbing or ropes to tie down. Bows do not have to be removed manually, since they move automatically with the tarp. The Crank-N-Go has a framework that slides along cables mounted an each side of the dump truck body or trailer. Manual cranking slides the tarp and bows forward or backward over your load. It can be operated from the ground or cab, for extra safety.

Power for deployment of the tarps is provided by one of three manual models or one electric model. Manual drives include V-belt drive, chain drive for longer trailers, and double V-belt drive for dump body cab shields. Electrical drives are provided for ease and convenience.

Pioneer Cover-All
Pioneer has developed a new Rack ’n Pinion design whose geared mechanical movement prevents what is often a serious problem in traditional, cylinder-driven pivot arms. In cylinder tarping systems self-weight could cause the system to collapse when the pivot arms are deployed at the 12:00 position. The combination of roller assembly and cylinders at the end of pivot arms translates to over 1,000 pounds of weight that often comes crashing into containers and/or cradles. The stresses and strains induced into the system by self-weight result in additional repair and maintenance costs. The system’s precision mechanical movement reduces potential damage, can easily adjust for 20- to 50-yard-capacity boxes, eliminates side arm free fall (and resulting dangers), allows for a precise synchronized deployment of the tarp, and prevents damage to the roller assembly.

Pioneer has also patented a telescoping side arm system that minimizes bending movements on the system’s structural elements and allows for variable-length tarp deployment. The hydraulic cylinders are enclosed for protection against the elements. The arms come with quick-disconnect pins that allow for easy replacement or repair. Less expensive, fixed-length side arms are available for transporting single-size containers.

Driving this system is the HR4500R hydraulic covering system with adjustable length low-arms, fixed gantry, and Rollmaster roller assembly. This system is recommended when covering 20- to 50-yard containers. The truck’s own hydraulic system is used to power the HR1500H. The connection between the tarp roller and the truck hydraulics is made with by a right angle hydraulic direct-drive gear motor. A hydraulic gantry is used to deploy the rolled tarp, using pivot arms (constructed of heavy-duty steel tubing) to cover the load. Reverse-wound torsion springs act in combination with the pivot arms to maintain tautness during deployment of covers up to 16 feet in length.

American Rolloff and Automated Waste Equipment Co. Inc.
American provides six types of rolloff box loading systems. The XT is the heavy-duty series (60,000- and 75,000-pound capacity utilizing a dual tire lift axle and either an inside/outside or outside rail), the industry’s heaviest constructed and maintenance-free rolloff hoist available. Built to last, the XT comes with high-strength steel in pins, hinges, and rollers. Its hydraulic system utilizes a 70-gallon tank reservoir. All its major components (cylinder, roller, and sheave pins) are removable, not welded into place, to allow for ease of repair and replacement.

The IC series is an interchangeable system (also rated at 60,000- and 75,000-pound capacity utilizing a dual tire lift axle and either an inside/outside or outside rail). Designed for ease of maintenance, it uses interchangeable cylinders for different anticipated loads.

Single rolloff hoists are available for a variety of applications: lift gate containers, recycling bodies, and spreaders. Custom-designed for individual truck chassis, these hoists can manage containers from 16 to 24 feet in length. Lift gate containers are available for white good collection, container delivery, wood chipping, and Porta-John delivery. Recycling bodies can be used for delivering recyclables to market, bulk waste collection, storm cleanups, or salt spreading. The tailgate spreader attaches to a standard rolloff-based box and can also be used as a dump body.

Daniel P. Duffy, P.E., is an environmental engineer in Cincinnati, OH.

MSW - May/June 2005