After more than 20 years of public interest, the operation of landfills continues to evolve. Today's operators are making changes in response to Subtitle D as they try to avoid the often-exorbitant costs associated with compliance.

Proper landfill operations and procedures should be based on several goals, including environmental protection and minimizing costs and liability. While protecting the environment is important, environmental repairs are costly.

Other operating goals include:

* Meeting regulations and maintaining the integrity of liner and leachate collection systems;

* Controlling surface water run-off to prevent erosion or ponding of over-filled areas; and

* Monitoring the waste stream, leachate, groundwater and surface water constantly to detect any problems as quickly as possible.

Potential Problems Everyone who owns, operates or contributes waste to a landfill faces liability if there is an environmental problem. Because of the high costs involved, liability is one of the most critical elements in the operating goals. In addition to clean-up costs, fines for improper disposal or other regulatory infractions can be severe and can cost thousands of dollars per day for each violation.

Solid waste management costs can be minimized by landfilling the maximum amount of waste in the smallest possible volume. Reducing the amount of cover soil used and minimizing cover soil erosion and equipment operating time also can cut costs.

Most municipal waste landfills are not designed, constructed or operated to protect the environment when disposing hazardous waste. Environmental protection includes ground and surface water control as well as control of vectors to minimize the spread of disease. Migrat-ing landfill gas is another concern because of its ex- plosive nature and toxicity to vegetation. The Clean Air Act addresses controlling the release of landfill gas to the atmosphere.

Waste stream monitoring helps to identify hazardous wastes before they are inadvertently deposited in landfills. Such wastes can be recycled or properly disposed at a hazardous waste facility, which can prevent legal penalties and protect landfill personnel from exposure to hazardous materials.

Waste stream monitoring also ensures that special wastes, including tires and white goods, are properly managed to prevent future problems such as tires working their way out of the landfill. It also prevents wasting valuable lined landfill space on bulky recyclable items such as white goods or auto bodies. In many cases, state and federal regulations prohibit these items from landfills.

Operating Techniques Compacting materials conserves valuable lined landfill space by confining the waste to the smallest practical volume. Properly compacted waste provides a smoother surface for daily cover application which requires a smaller amount of cover, minimizes material installation costs and leaves more room for waste disposal.

To control erosion, it is important to manage surface water run-off properly by planting grass or using synthetic mats or other materials designed for this purpose. Ero-sion control reduces cover repair costs. If erosion is not controlled and becomes severe enough, run-off that is exposed to refuse may have to be managed as leachate, which is more expensive than managing clean stormwater.

When eroded soil is deposited in surface water management facilities, the facilities must be cleaned or repaired. Erosion of soil into state or federal waters, which can result in substantial fines, can be minimized or prevented by properly filtering through sand or vegetative filters.

The landfill operator's main defense in groundwater protection is a properly functioning landfill. The liner is usually covered by protective layers of fabric, net and/or soil. The material included in the first layer of waste placed over the liner should be selected to ensure that it does not contain long, sharp objects such as boards, pipes or posts, which could be forced through the protective layer and damage the liner. Waste spreading and compacting in this layer must be done carefully. Equip-ment should operate only over waste placed in at least two-foot layers.

If the liner is punctured, it must be repaired by a qualified liner installer. A qualified engineer or laboratory should test and certify the repairs. Involve the manufacturer and the installer of the original liner to maintain any warranties.

Federal and most state regulations limit the leachate head allowed over the liner. The leachate collection system's integrity can be maintained by following the initial spreading and compacting procedures.

Following the deposition of waste in the landfill, the leachate collection system must be inspected and maintained on a regular basis, which includes video inspection of leachate lines and hydro-jet cleaning as necessary. Leachate quality and quantity must be regularly monitored so that any rapid changes can be investigated and repairs can be made and documented by qualified personnel.

Efficient landfill operation is crucial to controlling disposal cost. Proper daily operation will protect the liner and leachate collection systems, ensure optimum space utilization and minimize liability.