What do landfill managers, owners, and operators do to stay on top of the process?

JC: Landfill managers/owners/operators are primarily concerned with landfill development and proper waste disposal as their "core business." Landfill gas management is not considered core business, and RTC's experience has shown that landfill managers prefer to outsource this responsibility to a third-party developer. This allows the landfill manager to focus on core business. If a third-party developer option is not feasible, the manager must plan to design, permit, and construct landfill gas collection systems for installation as soon as landfill cells reach design-height maximums.

Air permitting must not be underestimated, especially for landfills located in severe ozone nonattainment areas. Air-permitting approval is required for a landfill gas combustion device. The landfill manager typically must employ an environmental manager experienced with landfill gas collection system permitting requirements or hire a reputable contractor to do it.

Landfill managers must be prepared to perform the operation and maintenance aspect of the landfill gas collection system. This involves system repair/adjustment primarily as a result of differential landfill settlement. Collection system tuning and monitoring is a must to proactively deal with settlement problems. A settlement problem, left untreated, can lead to pipeline blockage from condensate buildup and entire system shutdown.

BJ: The most basic landfill gas process is the anaerobic bioreduction of landfill mass. This process produces methane, CO2, and other nonmethane organic compounds, all of which contribute to global warming and the greenhouse effect, as well as to fire and explosive hazards, closed-quarter asphyxiation problems, and groundwater contamination. Any gas management program must address these issues as they apply to the specific site.

The first steps in producing a landfill gas management plan are to develop and install a gas monitoring system and to determine site-specific gas production rates. The first item should delineate site-specific probable hazardous areas. The second item will provide the owner/operator with an understanding of where the site stands regarding overall gas production. Based on information from the gas monitoring system, the calculated production rates, and other site data, the owner/operator can develop a gas control system. This can be as small as a free vent system or as large as a fully active gas system with flares. Once a system is installed, the work of monitoring and operating a system begins. Because in many cases the landfill will still be active, the gas control system may be installed in stages as the need arises. At this point, the owner will stay on top of the process by operating the monitoring system and maintaining gas control.

BF: As a manufacturer and distributor of methane-gas collection systems, we have seen that in the past few years the products that are available for collection, monitoring, disposal, etc. have made the job of monitoring and maintaining these systems more cost-effective. For example, the utilization of products from LFG&E [Santee, CA] has decreased field time in the monitoring. Through the years polyethylene resins have been developed for pipe that result in greater flexibility, increased tolerances of heat, etc. The cell classifications have changed three times in the past four years for higher tolerances of the American Society for Testing and Materials categories within the cell classifications.

GC: Landfill managers who stay up to date in the field go to the SWANA landfill gas meeting every spring. Some of them also go to Sardinia for the landfill conference and follow MSW Management.

KC: Generally when an energy end user is involved, SCS sees an onsite manager who is involved in wellfield optimization and power-plant operation. The owner contracts with SCS Field Services to obtain a permanent presence of a skilled landfill gas technician at the plant. Operating plants typically have a full-time presence. If the plant is not yet delivering landfill gas, we typically maintain the wellfield with weekly visits to the site. The economics are such that the differences between a well-run plant and field more than justify the increased personnel costs.

WC/KB: Those wishing to be at the forefront of landfill gas management typically ally themselves with a good consultant or researcher who can keep them apprised of innovative trends and proven technologies. It has been our experience that some landfill owners in the private sector rely heavily on consultants to keep them informed about landfill gas issues, while others hire internal landfill gas specialists. They also maintain contacts with companies that buy the gas for some specific end use so that they can take advantage of any opportunities. Responsible officials in the public sector rely on their landfill managers to comply with landfill gas regulations, while some of these managers seek the advice of consultants whenever possible. Attendance at industry seminars and conferences is another way to be informed; however, the trend in some organizations is to overload panel members and conference-organizing directors with a restricted representation of only limited viewpoints. This subsequently skews the direction of such conferences toward selling services instead of sharing information. This can be offset by identifying and staying in touch with knowledgeable researchers in the field, which is one of the most effective ways of maintaining one's landfill gas management expertise.

GB: Read current literature, attend seminars on the subject, check with consultants, and network with other solid waste professionals.

What are the consequences of not staying on top of the process?

JC: The consequences can be (a) collection system settlement/condensate blockage/shutdown, (b) offsite migration of landfill gas to groundwater, (c) landfill gas seepage through landfill cap and associated stressed vegetation, (d) odors to surrounding community, (e) compliance violations and fines, (f) reduced opportunity to attract a third-party landfill gas developer to pay for capital expenditures regarding future energy sales, and (g) negative effect on applying for future landfill expansions.

BJ: Assuming that one has an active gas system, the following problems may occur: (a) watered-out gas lines, (b) overpull or underpull on the gas wells, (c) well loss to watering out or movement in the landfill, or (d) fouling of the gas-flare system. These problems can result in improper gas collection and combustion, therefore leading to gas migration off-site (into both the ground and the air).

BF: If there happens to be a contract for the gas to be utilized by another source, you will probably have an angry customer. If it is meeting regulation, then you are probably not in compliance and could be subject to fines or penalties.

GC: The manager who falls behind has a landfill that does not manage its gas in the most efficient manner. The field is always in flux.

KC: SCS has seen sites where the landfill's ability to generate gas is destroyed by overdrawing on the system. This is the most obvious and most detrimental result of a neglected wellfield. Field technicians monitoring the percent of methane gas, oxygen, and nitrogen can tell when a landfill is being overdrawn. In addition, some Midwestern and Eastern sites with a history of drainage or infiltration problems experience a watering-in of the wellfield over time. This is a costly condition that results in a reduction of collection efficiency.

WC/KB: The most significant consequence is obviously noncompliance with the regulations. In some cases, if gas migration is allowed to continue for extended periods of time, a reduction in groundwater quality can occur through the condensation of volatile organic compound components in landfill gas and subsequent leaching into the groundwater. Furthermore, stressed vegetation on the landfill cover from the lack of control of landfill gas can lead to erosion problems and unsightly landfill covers. Odor problems often get a lot of attention as well. These consequences frequently result in expensive mitigative and remedial actions imposed by state regulators. The regulators might have been dissuaded from applying onerous closure requirements (e.g., groundwater pump and treat and/or HDPE final cover) if landfill gas management and conjunctive-use applications (gas extraction and groundwater cleanup) had been suggested.

GB: Not being able to maximize uses of the gas and maybe operating expensive, inefficient systems.

What tools and equipment make the various tasks easier and reduce the risks?

JC: The LANDTEC GA 90 or an equivalent landfill gas monitoring device for wellfield tuning. As-built drawings of the collection system, complete with piping profiles, will ease the pain of troubleshooting collection-system operation problems. Access to an experienced heavy-equipment operator to expose piping for maintenance. HDPE fusion machines for pipe ranging from 2 to 16 inches in diameter (a few larger landfills might justify an even larger pipe diameter). Spare parts inventory for HDPE and PVC pipe/fittings (for typical header piping and vertical extraction wells, respective materials of construction). The marketer of these materials can assist landfill managers with this spare-parts list. Establishing and implementing a preventative maintenance program for the landfill gas combustion equipment. Follow the manufacturer's guidelines for scheduled maintenance.

The single largest factor in reducing risk with landfill gas collection systems is proper design and investing sufficient capital in the wellfield and header piping system. You get what you pay for with landfill gas collection systems. Regardless of the sophistication of landfill gas combustion or monitoring technology used, it's only worth scrap value without a high-quality landfill gas delivery system.

BF: Obviously, the more you put into your system, the more you get out. Some systems are overdesigned, some are underdesigned. But utilizing certain products for the right applications can decrease costs as well as labor. We have also seen new design innovations from several engineers and owners. I guess you can say that they are "going against the norm." But what is the norm?

KC: Use of a LANDTEC GEM-500 gas extraction monitor by properly trained technicians can provide great guidance. Use of dual extraction wells in a wellfield can guard against watering in.

WC/KB: The most effective tool is knowledge. A landfill owner/operator needs to be able to read any signs of a problem with a landfill gas collection system, i.e., abnormal readings, stressed vegetation, and odor problems. There are various instruments used to monitor landfill gas, but the most effective ones are those built specifically for landfill gas monitoring, not those built for monitoring a specific gas component (usually methane). Tools such as comprehensive database programs (e.g., the Access database we use for landfill gas trend analysis and overall gas and groundwater management) and Excel spreadsheet models (landfill gas production and leachate recirculation) are crucial to a well-planned landfill gas management program. In the field, analytical tools such as GEM-500 and the HP Chemical Analysis Products field gas chromatograph accelerate decision-making and save money previously spent on laboratory analysis.

GB: Utilize a good gas collection system and perform tests as outlined in permits to make sure the system is performing as designed.

What are the cost tradeoffs between manual and automated gas management strategies?

JC: RTC's experience with this topic relates primarily to our landfill-gas-to-electric power plants. These plants can generally be described as "automated." The engine manufacturers ensure that the engine/generator sets can automatically adjust for changes in landfill gas fuel quality (e.g., variations in methane content). A general comment is that automated systems (e.g., auto flare igniter systems) are worth the extra cost when marginal manual labor rates and the potential environmental compliance issues of a collection system shutdown are factored in.

BJ: Automation of all aspects of gas management downstream of a collection system has proven to reduce personnel costs. Still, operational problems exist in collection systems. To substantially reduce cost of condensate disposal, we automated a condensate recycling system, whereas previously condensate had been taken offsite for treatment. The system had a one-year capital cost payback time.

GC: To run in an efficient manner today, at least the blower/flare/energy system has to be under the control of a well-designed programmable logic controller (PLC) system. There is no good way to do this on manual control. The PLC will normally take a week or two to tune. A canned PLC, as supplied in some cases, is no better than manual control.

KC: Most of the Midwestern systems that we have seen installed as a result of Section 29 tax credits have warranted a full-time operator rather than an automated system. [Section 29 tax credits provided a financial incentive for developers to install systems before June 30, 1997. The incentive has since expired.] Automated controls and automated dialing systems are important to include in any design, but we have not seen systems that remove the need for an operator.

WC/KB: Manual systems appear to be more cost-effective at the present time. Certain problems can only be recognized by a person, and undetected problems in automated systems can lead to costly repairs. In addition, it seems plausible that the cost of a monitoring round once per week or every two weeks would be much less than the headaches and operational costs involved with an automated system. As technology increases, there might be a point in the future when an automated system is more cost-effective. Automated landfill gas management can be very expensive and can lull the owner/operator into a false sense of security. Some degree of automation is acceptable and even required; however, the overall hands-on approach to landfill gas monitoring and system manipulation is still desirable.

GB: Manual systems are low maintenance and low cost but do not efficiently collect the gas. There is no opportunity to utilize landfill gas for energy or other purposes with a manual system.

What does the future hold for landfill gas management and how will we meet these challenges?

JC: It will continue to be dictated by federal and state regulatory standards (e.g., New Source Performance Standards for Municipal Solid Waste Landfills, promulgated March 1996). While not all landfills will trigger these regulatory requirements (and subsequently be forced to install an active landfill gas collection/combustion system), the trend toward larger regional landfills will result in a much higher percentage of landfills falling under these regulations. Landfill managers can meet this challenge either by budgeting annual capital expenditures for landfill gas collection and combustion systems or by contracting with a third-party landfill-gas-to-energy developer to absorb a portion (or possibly all) of the capital expenditures. They will also need to factor in the increased environmental recordkeeping/reporting requirements into their staff workload.

Regarding market potential for landfill-gas-to-energy, the future is very bright. Barely 10% of suitable landfill-gas-to-energy candidate landfills have implemented energy sale to an end user. For landfill-gas-to-energy (electric or direct fuel) facilities to be competitive with the utilities, it will be imperative that a number of landfills partner to sell a larger grouping of "green power" to the market. This is primarily for reliability of the energy supply. A larger grouping will ensure that the energy end user will not experience interruption in the supply.

Landfill-gas-to-energy industry growth will also depend on continued public and congressional support in the form of federal and/or state economic incentives (e.g., tax credits) for this renewable power source.

BJ: At this time, we are seeing a closing down of tax credits for gas projects. Simultaneously we are seeing increasingly larger landfills being built. These new landfills have the potential to produce more and more landfill gas. The challenge that we as an industry must face in the future is how to develop economic uses for the gas produced. To meet this challenge, we must plan to work with groups outside of our own industry---i.e., the end users---so that we can better develop a market for our product.

BF: We see the future as very positive. Whether incentives-such as tax credits-are given out or not, the collection has to be done. In the past year, we have seen several companies make these systems work without tax incentives, in the form of contracts between a buyer and a seller.

GC: The value of having the gas under good control can only go up, and as a result all sites will have to keep systems on review and should have an engineer on retainer who has a wide and deep background in landfill gas.

KC: Direct-energy-use projects have been successful throughout the Midwest. This was a trend that appeared unexpectedly and repeated itself with several different ownership groups. Other sites remain, which might allow this trend to continue.

WC/KB: Landfill gas management must be considered as only a single part of the entire landfill "organism." A holistic approach is required if the entire landfill animal is to be understood and satisfactorily controlled. For example, the landfill cell design and construction must balance the expected leachate production and recirculation/treatment, which in turn must be balanced (and partly dictated) by the operation of the landfill gas management system. We can meet these challenges only by viewing the landfill as a resource waiting to be tapped and knowledgeably developed. We must integrate all facets of the landfill design and construction such that the final result is a tamed organism that predictably functions and progressively degrades to a reclaimable and restorable resource. As the size of modern landfills is ever increasing, the use of landfill gas as an energy source becomes more attractive. The challenge here is to ensure that collection systems are designed to operate at optimal extraction rates and efficiencies, such that the energy source is optimized and the landfill environment is controlled. To accomplish this, we need to maintain detailed records and databases of successful and unsuccessful landfill gas collection systems. As landfill gas control technology ages, our databases and knowledge can increase dramatically. Whenever possible, case studies that span the life of a collection system should be developed and evaluated. As with any engineering discipline, we need to learn from our mistakes and constantly improve our designs through a combination of both theoretical processes and practical knowledge. .

How and where does the bioreactive landfill fit into the equation?

BJ: Anaerobic bioreactor landfills will become increasingly important to the future of MSW landfills. The dry-tomb landfill will become a thing of the past; the concept is being perceived as too costly to continue from both an operational and a risk standpoint. The bioreactor landfill will accelerate stabilization of the landfill with the benefits of regaining space that was not available for landfilling and reducing time for monitoring after closure. Another benefit is an increase in the production rate of landfill gas, which might allow for better utilization of the gas. Finally, as we stabilize MSW, we reduce the risk of environmental problems in the future. As the cost benefits of the bioreactor are better understood, more operators will pursue this as a way to operate MSW landfills. As more data are gathered, we will continue to see fewer political and regulatory hurdles for these types of operations.

GC: To get the best results, all landfill gas systems will have to be treated as a part of a bioreactive system subject to adjustment as conditions change. This means both equipment and controls need to work well over a wide range.

KC: Most involved in landfill design see the bioreactive landfill as the next logical step in long-term protection of our environment. Landfill gas designers would be wise to anticipate this fact in designing landfill gas systems.

WC/KB: The bioreactor landfill is simply one integral part of the living landfill organism; however, this is a part that is critical to the progressive development of the landfill as a resource to the community, not a detriment. Bioreactive landfills as they pertain to landfill gas management have to occur in a controlled, lined landfill environment. Landfill gas management is just one piece of the puzzle when it comes to bioreactors; leachate management, waste-placement practices, and waste composition play important roles as well. For a landfill to act as a true bioreactor, the waste degradation process must be optimal. Proper landfill gas management is a key factor in this optimization.

GB: Recirculating leachate would speed up the degradation of organic waste and landfill gas production as well.