Handling garbage causes problems. As a result, the elements that exist in both rural and urban transfer stations potentially threaten workers, customers and the surrounding environment.
One way to effectively and inexpensively control the negative effects of dust, odor, noise, wastewater, litter and fire is by incorporating certain design elements into the basic building systems.
For example, solid waste loads contain dust, which is aggravated during waste unloading and transfer. When the solid waste facility is not enclosed by a building, a windy day can cause a virtual dust storm in the area.
The first step to controlling dust during waste transfer is to enclose the waste handling area within a building. Even when the building has large access doorways for vehicle and trailer traffic, enclosure can control dust if the building is situated so that wind does not blow directly into openings. Sweeping and washing down the waste transfer areas every day also helps to keep them free of dirt and debris.
If the construction budget allows, install ventilation fans high in the side walls of the building or in the roof to pull air and dust away from customers and transfer station workers. These fans mix the dust with a large amount of air and exhaust it outdoors at a height where it disperses before reaching the ground. A simple ventilation fan system for a small transfer station typically costs less than $5,000.
In some transfer stations, ventilation fans may be used in combination with a water misting system, which consists of low-volume fogging nozzles that are installed around the edge of or over a waste unloading area. Large amounts of dust activate the nozzles, which spray a fine mist over the waste unloading area, knocking the dust out of the air. Properly designed misting systems can battle dust without adding a significant amount of water to the waste. A water misting system will generally cost between $1 and $3 per square foot of misted area.
Odor And Noise Control While garbage causes odor at any transfer station, a properly designed building system will include plans for odor control. For example, buildings for waste handling areas should be designed so that waste is not easily trapped behind or between structural components. Floor areas inside the building should be sloped toward a drain to prevent standing water that has been in contact with refuse. Water collected from building drains should be discharged to an enclosed holding tank or sanitary sewer. Building openings should be located out of the path of prevailing winds to prevent the wind from blowing through the building and carrying odors to neighbors.
An operating plan that requires daily cleanup and washing of waste handling areas is another important odor control method. Rapid movement of the waste through the facility - normally within 24 hours and up to two weeks for remote rural areas - also helps to prevent odor. The operations plan should identify the maximum storage times for waste on a tipping floor and for full transfer trailers that are waiting to be hauled.
Arriving and departing vehicles create almost unbearable noise in a transfer station, but several methods can decrease its impact. For example, grade access and site roads to minimize road slopes to cut down on the gearing and engine noises when large trucks haul loads up an incline; install engine mufflers on site equipment; provide landscaped or vegetated buffer zones, preferably of 20 to 100 feet, between the facility and its neighbors; and limit the transfer station's hours of operation to normal work hours.
To minimize noise:
* Enclose the transfer activities within a building that has limited entrances and exits so that customers maneuver vehicles inside. This will reduce noise escaping the building.
* Install building doors on the access openings that remain closed except when the vehicles pass through the opening.
* Install siding on the building to interrupt the free movement of noise inside. Experience has shown that a transfer building with wall siding will substantially reduce the amount of noise that will leave the site. Insulation in the interior of the building further reduces noise transmission.
* Orient the building so that access openings do not face neighbors. If this cannot be avoided, try using earth berms, sound-absorbing walls or barriers and landscaped buffer zones.
Wastewater And Litter Water that comes in contact with refuse is considered hazardous and cannot be disposed in storm sewers or in a septic system. It must be removed from the site and treated at a wastewater treatment facility. Since it is expensive to dispose wastewater, minimize the amount created.
The only water that should be collected as wastewater is that which arrives with waste loads and which is used to clean the waste transfer area. Enclose the waste transfer area and slope the rest of the site away from the transfer building to keep rainwater from coming in contact with refuse. The floor areas inside the building should be sloped to a drain, and the drains should be piped to a holding tank or sanitary sewer. If a holding tank is used, pump it at regular intervals and transport the water to a treatment facility.
Transfer building design, orientation, wind screening, site fencing and clean-up help control litter at the site and prevent its migration onto nearby properties.
The most economical litter control method is to completely enclose the site with walls. Identify the principal wind directions to orient the transfer building on the site so that openings will not face into the wind.
The optimum design, which allows room inside the building for the customer vehicles to maneuver, is more common in urban areas where neighbors are nearby or where tolerance to other environmental factors such as noise, odor and dust is low. This method is mainly used at large-capacity transfer stations that handle at least 500 tons of waste each day.
To screen the wind from the transfer station, two methods can be effective: a roofless building, or windproof barriers or deflectors surrounding an open transfer building with a roof. The roofless building approach, in which high walls shield the waste transfer area from the wind, is applicable only in areas where precipitation is low. For this method to be effective, the designer must consider the height of the walls relative to the waste transfer area dimension parallel to the wind direction. Short walls and a long dimension parallel to the wind will result in the flow of wind over the walls and directly into the area which is supposed to be sheltered from the wind.
Wind screening using windproof barriers or deflectors must be designed to be stable in the wind to avoid damage or possible customer injury, and must be located close to the waste transfer area.
Fencing the site to control litter is only marginally effective because litter can move away from the ground. A litter-control fence should be at least six feet tall and preferably eight feet tall, and can be installed in a series, to be effective. Litter control fences also must be cleaned frequently so that they don't get clogged and become wind deflectors, directing litter up and over fences. Wind fences can be permanently installed or moveable. Permanent fencing costs from about $9 to $18 per linear foot. Moveable fences can cost $1,500 to $3,000 for a 20-foot section.
Litter clean-up should only be considered to back up other litter control methods. Once litter leaves a transfer station site, it becomes an eyesore and a nuisance that can be expensive to clean up.
Fire Control A transfer station's fire control measures are governed by the Uniform Building Code (UBC), Uniform Fire Code, the National Fire Protection Association (NFPA) and the fire marshal's interpretation of these codes. The UBC building occupancy rule determines the method of fire protection to install. In addition, a fire marshal's interpretation can result in discrepancies between stations that are similar in design but located in different areas.
Common methods of fire protection include portable fire extinguishers, standpipe hose stations, fire hydrants and fixed sprinkler suppression systems. Depending on their capacity, portable fire extinguishers are either hand-held or cart-mounted. Extinguishers are typically located at entrances and exits in the transfer building. Generally at least two extinguishers are provided, and more may be required if the transfer building is enclosed or if it contains hydraulic oil-actuated equipment.
Standpipe hose stations are rated by NFPA for occupant, fire department or combined use. They can be dry or full of water, depending on climatic conditions, and are specially designed and located to provide up to 500 gallons per minute of water for 30 minutes. The building must be within 150 feet of a standpipe, which should be located in fire-rated areas or outside the building. A maximum of 100 feet of hose must be on a rack and attached to the standpipe, ready for use.
Fire hydrants are normally outside, full of water and pressurized and required to deliver 1,000 gallons per minute of water for 60 minutes to a fire hose. With the fire marshal's approval, the flow requirement is often reduced to 500 gallons per minute for 60 minutes. Fire hydrants are usually within 150 feet of all structures.
Fixed sprinkler suppression systems fall into two major categories: wet pipe and dry pipe. Selecting the type of system depends on climatic conditions. Both sprinkler system types involve installation of piping and sprinkler heads throughout the transfer building. The systems are designed to spray approximately .13 gallons per minute of water per square foot of protected area. The water supply to these systems is generally required to be at least 800 gallons per minute for 60 minutes. A sprinkler system costs between $3 and $5 per square foot of protected area plus the cost of the water supply system.
All of these fire protection methods (except the fire extinguisher) require a water supply system capable of providing 500 to 1,000 gallons per minute for 60 minutes. When a public water main provides the water supply, the cost will be minimal compared to the transfer station construction cost. If a public water main is not available, the cost to develop a well or a long-distance pipe-line can be considerable - an 8-inch water line can cost as much as $40 per linear foot to construct.
Another option is to construct a water well, storage tank and fire pump station. A water well capable of delivering 10 to 20 gallons per minute will cost $30 to $40 per foot of depth. A 60,000-gallon water tank will cost approximately $35,000 and a 1,000-gallons-per-minute fire pump with an electric motor drive will cost approximately $40,000.
Public interest in solid waste projects and increasing awareness of environmental issues have changed the face of acceptable transfer station design. Many state and local laws now require transfer facilities to include features that will control impacts to the customers, workers and the surrounding environment.
Several of the building systems call for the same preventive measures. It is crucial to consider all the building systems as part of an integrated environmental control system and to work with an experienced designer to increase the effectiveness of your transfer station design.