Failure of Landfill Liner Systems

Detection of the Failure of Landfill Liner Systems

G. Fred Lee, PhD, PE, DEE and Anne Jones-Lee PhD =BR>G. Fred Lee & Associates
El Macero, California

It has been found that frequently, as part of permitting a new =andfill or landfill expansion, landfill applicants and/or their consultants will =laim that there is no evidence that the US EPA RCRA Subtitle C (hazardous waste) =ouble composite-lined landfills and Subtitle D (municipal solid waste - MSW) =ingle composite-lined landfills have failed to prevent leachate from passing =hrough the liner system and polluting groundwaters. This situation then leads =andfill applicants to try to convince regulatory agencies and others that, since =here is no evidence for groundwater pollution by the plastic sheeting-lined landfills, this approach must be protective of groundwater quality and =herefore a proposed landfill with this type of liner should be approved. =asically, the landfill applicants are trying to shift the burden of proof for =rotection of groundwater from the applicant to the regulatory agencies and/or the =ublic where it is up to the agency - public to prove that the plastic =heeting-lined landfills will be protective of the groundwater resources in the =icinity of the landfill for as long as the wastes in the landfill will be a threat. As discussed herein, such an approach is highly inappropriate.

Burden of Proof for Groundwater Quality Protection Should Be on the =andfill Applicant

It is important that as part of developing a landfill, the landfill applicant, whether public or private, be required to convincingly =emonstrate that a proposed landfill will be sited, designed, constructed, operated, =losed and provide post-closure care such that it will protect the groundwater resources, public health, environment and the interests of those within =he sphere of influence of the landfill, for as long as the wastes in the =andfill represent a threat. For planning purposes, the wastes in a municipal =olid waste landfill or the treated waste residues in a hazardous waste landfill =hould be considered a threat to public health, the environment and groundwater =esources forever (Jones-Lee and Lee 1993). It is now well-understood that today's =lastic sheeting-lined landfills that meet minimum or even somewhat above =inimum design requirements will, at best, only postpone when groundwater pollution =ccurs by landfill leachate generated within the landfill. This issue is discussed =n detail in the papers and reports developed by the authors. A list of =hese papers and reports is appended to these comments. Copies of them are =vailable upon request.

Since, as discussed in the report entitled, "Recommended Design, =peration, Closure and Post-Closure Approaches for Municipal Solid Waste and =azardous Waste Landfills," (Lee and Jones-Lee, 1995a) it is possible today to =evelop landfills that will be protective of public health, the environment and groundwater resources and the interests of those within the sphere of =nfluence of the landfill, the landfill applicant should be required to develop =andfills that will be protective for as long as the wastes in the landfill will =e a threat.

If there are questions about any particular landfill being =ppropriately sited, designed, constructed, operated and whether there will be =dequate post-closure care funding for as long as the wastes represent a threat, =.e., forever, then the landfill should not be developed or expanded. Those =ho own or use properties near proposed landfills should be protected from adverse =mpacts of the landfill. This will require those who generate wastes that are =laced in a landfill pay the true cost associated with landfilling the wastes. In =hose situations where there is inadequate information to evaluate whether a =roposed landfill will be protective, it is appropriate to err on the side of =rotection of public health, the environment and the interests of those who live =ear landfills rather than on the side of cheaper-than-real-cost waste =isposal. The cost of proper solid waste management only represents a few cents per =ay more for those who generate the wastes than the cost associated with minimum =ubtitle D landfills (Lee and Jones-Lee, 1993a). Similarly, the proper management =f landfill hazardous waste would not significantly increase the cost of =he goods that generate the waste.

Detection of the Leakage of Landfill Liner Systems

The basic reasoning (no pollution of groundwaters by landfill =eachate has been detected) that is being used in support of continued development of =Subtitle D minimum single composite-lined landfills and Subtitle C =ouble composite-lined landfills is fundamentally flawed for a variety of =easons. These issues are discussed below.

Travel Time of Leachate. The way that leakage through a Subtitle = single composite liner is detected is by pollution of the groundwaters at the =oint of compliance for monitoring the presence of leachate. The point of =ompliance can, in a properly developed landfill that complies with minimum Subtitle D requirements, be no more than 150 meters from the down groundwater =radient edge of the waste management units. This means that any leakage from a =ubtitle D landfill liner system must travel through the liner and unsaturated =eological strata below the liner to the groundwaters and then horizontally to the =oint of compliance. Since Subtitle D landfill liner systems have only been =equired by the US EPA for less than three years, it is entirely possible that at =any landfill sites the leakage through the liner that is likely occurring =as not yet reached the point of compliance.

Unreliable Groundwater Monitoring. One of the primary reasons why =Subtitle D and, for that matter, Subtitle C landfills have not been =ound to be polluting groundwaters is that the method of detection of groundwater =ollution involves vertical monitoring wells spaced hundreds to a thousand or more =eet apart at the point of compliance for monitoring. These monitoring wells =ave zones of capture into the aquifer of about one foot based on a three =orehole volume purge of the well before sampling. This means that unless there =s widespread general leakage throughout the whole bottom of the landfill =iner system, the plumes that are generated from initial leakage would not =ikely be detected by the groundwater monitoring wells. Parsons and Davis (1992) =ave discussed the approach that should be used to develop reliable =roundwater monitoring systems for lined landfills. Basically, the zone of capture =f the monitoring wells at the point of compliance for groundwater monitoring =ust be of such dimensions (lateral extent) to intersect the leachate plumes =hat arise from leaks through the liner system.

Cherry (1990) and Lee and Jones-Lee (1994a) have reported that =ypically the plumes that are developed from plastic sheeting-lined landfills are =ingerlike, i.e. with limited lateral dispersion. This creates a situation in which =he groundwater monitoring systems used have a low probability of detecting groundwater pollution before widespread pollution occurs beyond the =oint of compliance for groundwater monitoring. In most plastic sheeting-lined =andfills there will be several long, finger-like plumes of leachate extending =ell beyond the point of compliance before the failure of the liner system to =revent groundwater pollution is detected. This is one of the primary reasons =hy it is fundamentally flawed reasoning to assert that because the groundwater =onitoring systems at Subtitle C and D landfills have not yet detected groundwater pollution that these types of landfills will be protective of =roundwater resources for as long as the wastes in the landfill will be a threat. =/P>

Leakage Through Double-Lined Landfills. One of the best ways to =udge whether leakage will occur through a single composite liner is to =xamine the results obtained for leaks into the leak detection system for landfills =ined with double composite liners that have a leak detection system between =he two composite liners. Examining this issue is the best indicator available =t this time on what can be expected in the way of leaks through both the double =composite liner and a single composite liner landfill system. As =iscussed by Lee and Jones (1992), Bonaparte and Gross (1990) reported on finding =ignificant leaks in new landfills constructed with double-lined systems.

One of the issues that is of considerable concern with respect to =eakage through composite liners in a double composite-lined system is the =pproach that is used to establish excessive leakage rates through the upper composite =iner. Several years ago the US EPA attempted to establish a Liner Action =eakage Rate of a few gallons per acre per day as the rate at which a single =omposite liner in a double composite-lined system would be allowed to leak before =emediation efforts would have to be undertaken. As it turned out, based on the =eview by Bonaparte and Gross, allowing only a few gallons per acre per day of =eakage through the upper composite liner would mean that essentially all of the =pper composite liners of double composite-lined systems would be found to =ave failed. This caused the US EPA and the states to take a different =pproach where the Liner Actual Leakage Rate is based on what can be achieved with =urrent liner technology, rather than what is necessary to protect groundwater =rom pollution by landfill leachate.

As discussed by Lee and Jones (1992), the appropriate approach to =ake in establishing the Liner Action Leakage Rate is not what can be achieved =ith these types of liner materials, but what is necessary to protect the groundwaters from pollution by landfill leachate. This is the purpose of =he liners. The approach that should be used is to determine, on a =ite-specific basis, the rate of leakage through the upper composite liner that can be =llowed and not result in groundwater pollution if the lower composite liner =ere not present. For most situations, this will be on the order of a few gallons =er acre per day.

Development of Liner Leak Detection Systems. While landfill =pplicants and their consultants often claim that a single and/or double composite =iner system will not leak, it is obvious from the literature, principles of =hemical thermodynamics and common sense that such claims have no technical =alidity. The facts are that composite-lined systems often can leak at the time of construction due to imperfections in the construction. It is for this =eason that I-Corp International of Daytona Beach, Florida; Gundle - GSE of =ouston, Texas; and Robertson Barrier System Corp. of Vancouver, British Columbia =ave developed leak detection systems for liners. Such leak detection systems =re needed to detect leaks that are occurring at the time of construction of =he liner system that are not detected by conventional QA/QC approaches. =/P>

Landfill Operations Caused Leaks. Another important source of =eaks for new landfills is the inadequate protection of the liner system from the =nitial placement of the wastes in the landfill. Often inadequate attention is =iven to developing a protective layer between the liner system and the lowermost =ayer of wastes to prevent punctures from occurring in the liner system =ssociated with the initial placement of the wastes. An example of this type of =roblem occurred with Chemical Waste Management of Indiana's hazardous waste =andfill unit located near New Haven, Indiana where as part of placing the first =ayer of wastes in that landfill, the landfill operator punched 83 holes in the =iner. The leakage through these holes was of sufficient magnitude so that the =tate of Indiana required that the wastes that had been placed in the landfill be =emoved and the liners repaired.

Solvent Permeation. There is a special type of leakage of =andfill liners that, thus far, is largely being ignored by the regulatory agencies, =ven though it is well-documented in the literature. This is the problem associated =ith permeation of the liner by various types of organic solvents. Common =rganic solvents that are present in municipal solid wastes and in treated =azardous waste residues such as the chlorinated solvents, benzene, TCE and its degradation products such as vinyl chloride, etc., can pass through an =ntact, with no holes, flexible membrane liner in a short period of time. This =s a chemical process that does not cause the liner to deteriorate, but =nvolves the diffusion of the organics into the plastic sheeting and then through the =lastic sheeting into the media on the other side of the plastic sheeting which typically is the compacted clay layer. Permeation of dilute solutions of =rganic solvents through HDPE liners was discussed by Haxo and Lahey (1988). =his process has been investigated in detail by Sakti et al. (1991). =Recently, Buss et al. (1995) have published further information =n it.

It is important to note that this mechanism of leakage is =articularly significant since it results in the transport of highly hazardous =ersistent mobile constituents through the liner system under conditions where the =iner is perfectly formed and intact. It occurs not only from concentrated =olvent solutions, but also occurs with dilute aqueous solutions of the =olvents. The various solvents that are of concern can be purchased by the public at =he local hardware store and therefore are not exotic chemicals that would not be =xpected at a landfill, but are common chemicals that are expected in today's =unicipal landfills. Many of these solvents are known or expected carcinogens. The =S EPA (1988a), as part of promulgating Subtitle D regulations, noted that one =f the best ways to detect liner leakage of leachate is through measurement of =rganic solvents.

Long-Term Plastic Sheeting Liner Deterioration. Even if the liner =s perfectly formed and no holes are punched in the liner at the time of =aste deposition and if no organic solvents are present in the landfill, it is =till only a matter of time until the liner system fails to prevent leachate =rom passing through it. The US EPA (1988a), as part of promulgating Subtitle = regulations governing municipal landfills, stated,

"First, even the best liner and leachate collection system will =ltimately fail due to natural deterioration, and recent improvements in MSWLF =municipal solid waste landfill) containment technologies suggest that releases may =e delayed by many decades at some landfills."

The US EPA (1988b) Criteria for Municipal Solid Waste Landfills =tated,

"Once the unit is closed, the bottom layer of the landfill will =eteriorate over time and, consequently, will not prevent leachate transport out of =he unit."

Since the US EPA developed that position on the ultimate =eterioration of flexible membrane liners, considerable additional work has been done =hich now further strongly supports this position. A recent example of this is the =ork of Hsuan and Koerner (1995) where they have reported on the initial phase =f some long-term (10-year) studies that are underway on examining the rates of deterioration of flexible membrane liners. The focus of the Hsuan and =oerner's work is on the breakdown of the polymers in the plastic sheeting liners. =hey predict that this breakdown will occur due to free radical polymer chain =scissions in 40 to 120 years. These estimates are indicated by Koerner =o consider only some of the key issues that could cause breakdown. It is =ossible that breakdown could begin much earlier. Even if the breakdown of the =lastic sheeting polymers took 100 years or so, there is still no question that ultimately the plastic sheeting in the flexible membrane liners will =reak down leading to an inability to prevent leachate from passing through it =eading to groundwater pollution in the area.

It is important to put the ultimate breakdown of the flexible =embrane liner in the perspective of the time at which the treated waste residues in a hazardous waste landfill and in a municipal solid waste landfill =epresent a threat. Both types of landfills contain waste components that will be a =hreat, effectively forever. Therefore, since it is only a matter of time until disintegration of the flexible membrane liner occurs, it is only a =atter of time until groundwater pollution occurs at landfills lined with HDPE =lastic sheeting.

Compacted Clay Liners. Todays Subtitle C and D landfills require =hat the plastic sheeting layer(s) be backed by compacted clay. The minimum =esign requirements for the clay layer is two feet of clay that has a =ermeability, at the time of construction, of no greater than 10-7 cm/sec. =here are a variety of well known mechanisms (see Lee and Jones 1992) that cause the =compacted clay layers to increase their permeability over time. Factors =uch as desiccation cracking are important causes of increased permeability for =lay liners.

There is an increasing tendency to substitute thin bentonite mats of =lay for the two feet of compacted clay. These bentonite mats have advective permeabilities of about 10-9 cm/sec. However, the diffusional =transport through such layers is much higher than this amount. Gray =1988) has found that diffusion is a much more important process for determining =he transport through bentonite mats than the advective permeability. =urther, as discussed by Lee and Jones (1992), bentonite clays are subject to =ignificant shrink/swell properties where, for certain types of wastes that have =xcess calcium and magnesium over sodium, the sodium bentonite clay present in =hese mats would undergo ion exchange with calcium and magnesium, leading to a =shrinkage of the clay and increased permeability. There are significant questions about the advisability of relying on bentonite mats as a =eliable barrier for the transport of landfill leachate through them.

Overall, compacted clay layers will not prevent leachate transport =hrough them. They have finite permeabilities which will ultimately allow, under =esign specifications, the transport of leachate through the layer. Further, =here are a variety of mechanisms which can result in an increased permeability =rom that prescribed in the design and achieved at the time of construction. =/P>

Reliable Reporting on FML Properties

One of the problems with addressing the ultimate breakdown of the =iner system is the failure of landfill applicants and their consultants to =eliably report on the long-term stability problems with flexible membrane =iners. There are numerous examples in the literature such as Fluet et al. =1992), Tisinger and Giroud (1993) and Flood (1994) where individuals who work =or landfill applicants inadequately and/or unreliably report on the =ltimate breakdown of flexible membrane liners. As discussed by Lee and Jones-Lee =(1993b), the typical approach used by landfill consultants is to claim =hat the liner system will be "protective." However, they fail to discuss their definition of the duration of time in which they will be protective and =ail to mention the fact that, ultimately, this protective definition that they =se will result in groundwater pollution beyond the time that they are =onsidering to be of significance. Often this time is considered to be only 30 years =eyond the closure of the landfill.

As discussed by Lee and Jones-Lee (1994b), this 30-year post-closure =are period, which is mandated as the minimum for Subtitle C and D landfills, =s an infinitesimally small part of the total time that will ultimately have =o be considered during which the wastes in the landfill will be a threat to =ause groundwater pollution. Basically, the 30-year post-closure care period =as an error on the part of the US Congress and environmental groups which the =S EPA and Congress has yet to correct as part of the revisions of RCRA.

The problem of landfill applicants and those who serve as consultants =o them not disclosing the "whole truth" about the ultimate failure of the =andfill liner system to protect groundwaters for as long as the waste is a =hreat, is of sufficient concern such that the authors have developed a discussion of professional ethics issues. They discuss the situations associated with professional engineers failing to disclose the long-term public health =nd safety issues associated with a particular landfill as part of their =dvocating the construction of a landfill at a particular location based on a =inimum or near-minimum Subtitle C or D landfill liner - containment system design. =/P>

As discussed by Lee and Jones-Lee (1995b), professional civil =ngineers and those who are members of the National Association of Professional =ngineers are obligated to conform to the organizations' code of ethics which requires =ull disclosure of potential problems in those situations where public health =nd safety is at stake. This situation is routinely ignored by professional engineers, where they adopt an adversarial approach of only informing =egulatory agencies of the potential benefits of a particular landfill liner - =over containment and monitoring system design and fail to disclose the =ignificant long-term deficiencies with this design. This issue is discussed further =y Lee and Jones-Lee (1995b) where they recommend that the landfill siting =rocess be conducted in a true peer review arena where all advocates of a =articular position must present, for full public and peer review, the technical =asis for their position under the conditions where their peers can discuss the =alidity of that position.

Developing Protective Landfills

One of the issues that needs to be considered is whether Subtitle C =nd D landfills could be developed using the "dry tomb" landfilling approach =hat would be protective of groundwater resources for as long as the wastes =n the landfill represent a threat. Lee and Jones-Lee (1995a) have provided =uidance on how this can be accomplished. Basically, it involves the construction of =ll hazardous waste landfills and so-called non-hazardous waste landfills =sing double composite-lined systems with a reliable leak detection system =etween the two composite liners. This is the approach that is used in Michigan's =ule 641 for municipal solid waste landfills. Such landfills consist of a double composite lined system where the lower composite liner is part of a leak =detection system for the upper composite liner. It is also the approach =hat is used by the US EPA in Subtitle C landfills except that the US EPA has =ailed to develop adequate Liner Action Leakage Rates which will be protective of =he groundwaters in the vicinity of the landfill when the lower composite =iner is no longer an effective barrier and leachate passes through it.

The approach that should be followed is that whenever the leachate =eakage through the upper composite liner is sufficiently great so that the =roundwaters under the landfill could be polluted, i.e. impaired use for domestic or =ther purposes, by the leakage through the liner, then the landfill =wner/operator must stop the leakage through the upper composite liner or exhume the =aste.

Since this liner cannot be inspected and repaired without removal of =he wastes, stopping the leakage through it will require that an impermeable =over be installed on the landfill which has a primary component a leak =etection system that is operated and maintained in perpetuity, i.e. as long as =he wastes in the landfill represent a threat. The Robertson system, the Gundle =GSE leak detection system, the I-Corp leak detection system as well as others =hat are being developed can all potentially be used for this purpose. While =hese systems cannot function effectively in the landfill liner system, they =an be made to work in the landfill cover, which is accessible for repair.

Todays RCRA Subtitle C and D landfill covers involve the use of the equivalent of a composite liner in which thin plastic sheeting and a =ompacted clay layer is constructed on top of the waste layer. This low =ermeability layer is designed to minimize but not prevent moisture from entering the =andfill and generating leachate. Daniel and Koerner (1991) discuss the variety of =actors that influence the stability of a landfill cover such as the =ifferential settling of the waste which can be highly disruptive of the cover =ntegrity. Typically landfill owners/operators will assert at a landfill permitting =earing that if any problems develop in the integrity of the landfill cover, =hat these will be repaired. However, the low permeability layer of the landfill =over (the plastic sheeting and compacted clay) are buried below several feet of =op soil and a drainage layer. Cracks can develop in the low permeability layer =hich cannot be perceived upon visual inspection of the landfill cover. It is =or this reason that Lee and Jones-Lee (1995c) advocate that leak detectable =overs be used in Subtitle C and D landfills.

If the landfill owner/operator cannot or will not stop the leakage of =leachate through the upper composite liner, then the owner/operator must =emove (exhume) the wastes in the landfill, properly treat them, and manage the =residues from such treatment in such as way as to not lead to further groundwater pollution. Failure to adopt this approach will mean that the =aste in a landfill will pollute the groundwaters of the area. As discussed by =ee and Jones-Lee (1995a), such an approach requires that a dedicated trust fund =e developed from disposal fees during the landfill's active life. This =rust fund should be of sufficient magnitude to ensure that sufficient funds are =resent to operate and maintain the leak detectable cover, leachate collection =ystem and the leak detection system between the two composite liners. While other financial instruments are currently allowed in RCRA post-closure =unding, such financial instruments are likely to be unreliable. Hickman (1992, 1995) =as discussed the importance of using a dedicated trust as a reliable =inancial instrument to address long-term contingencies associated with "dry tomb" =ype landfills.

The typical 30-year post-closure fund associated with both hazardous =nd non-hazardous waste landfills is grossly deficient compared to the funds =hat will likely be required during the 30-year period, much less the =nfinite period of time that funds will be needed to address contingencies that will =ltimately have to be addressed at the landfill. An important aspect of this =ituation is whether private landfilling companies will, in fact, be economically =iable in the future when the funds will be needed--20, 50, 100 or so years from =ow. As discussed by Lee and Jones-Lee (1993c, 1994b), private landfilling =ompanies are accruing massive liabilities that ultimately will cause these firms =tockholders to sell their stock from the firms, making the firms financially =nstable, ultimately leading to their bankruptcy. This past year, at the annual =eeting of the Waste Management of North America Stockholders, the WMX CEO, D. =untrock, noted that WMX was losing money on its hazardous waste management =usiness. D. Buntrock is quoted in the Chicago Tribune as stating at this meeting, =EM>"Most of us in the company wish today we never heard of the business." =ituations such as this give little confidence that landfill companies will, in =act, meet their long-term obligations associated with post-closure care of =andfills.

The US Congress General Accounting Office (GAO 1990) informed =ongress in a report entitled, "Hazardous Waste Funding of Postclosure Liabilities =emains Uncertain," that the current regulatory approaches do not necessarily =rovide the funding that will be needed to address contingencies during their post-closure period, i.e., while the wastes remain a threat. Further, =he GAO (1995) has reviewed the potential for funding the monitoring and =aintenance of hazardous waste landfills and concluded that, at this time, there are =igh degrees of uncertainty about whether federal and state funds will, in =act, be available to provide for monitoring and maintenance and periodic (five =ear review) of hazardous waste landfills in accord with current regulatory requirements.

Some states, such as South Carolina, are beginning to address this =ssue by requiring that waste management companies post cash bonds to address =ong-term landfill contingencies.

While generally today, regulatory agencies are not adequately =ddressing the long-term issues associated with municipal and hazardous waste landfills =ultimately failing to protect public health, groundwater resources and =he environment from waste derived constituents, there is growing =ecognition of the deficiencies of current regulatory approaches where the minimum landfill =esign for Subtitle C and D landfills is recognized as being badly out of date =nd not protective of public health and the environment for as long as the =astes in the landfill will be a threat. An encouraging situation recently developed =n the state of Indiana where the Hazardous Waste Facility Siting Authority =eviewed a Chemical Waste Management of Indiana proposal to expand a hazardous =aste landfill where it became clear, that ultimately, that landfill would =ollute groundwaters of interest to the city of New Haven which is located =mmediately adjacent to this landfill. The Siting Authority concluding in an eight =o one vote that the landfill should not be expanded because of its potential =o ultimately pollute groundwaters of interest to New Haven, Indiana.

With respect to Subtitle D landfills, a number of states, such as New =ork, New Jersey, Michigan, Pennsylvania, Kentucky, Oregon and Arizona, have =dopted double composite-lined landfills as the minimum landfill liner design =or situations where there are groundwaters underlying the landfill that =ould be polluted by landfill leachate at any time in the future. California has =ad regulations (Water Resources Control Board, Chapter 15) since the mid =980s that require that hazardous waste landfills not leak leachate through the =iner system for as long as the wastes in the landfill represent a threat, and =municipal solid waste landfills not allow sufficient leachate to pass =hrough the liner system to potentially impair the uses of the groundwaters =ased on the concentrations of constituents in the unsaturated zone underlying the =andfill for as long as the wastes represent a threat. While, such approaches =ppear, from a regulatory perspective to be highly protective, in fact, based on =he way in which the Chapter 15 regulations have been implemented at the =egional board level do not provide for this level of protection. Instead, the regional =oards have been allowing landfill applications to construct landfills that, =bviously, will not protect groundwaters from pollution by landfill leachate for as =ong as the wastes in the landfill will be a threat.

The justification for this approach is based on that mention is made =n the regulations of minimum landfill liner cover - containment system design requirements. Even though the regulations explicitly state that the =inimum requirements are not necessarily protective at all sites and that the =iner cover - containment system must protect groundwaters from impaired use =or as long as the wastes in the landfill represent a threat. The inappropriate =interpretation of the regulations that is routinely occurring today in California by regional boards where the minimum design is determined to =e equivalent to the groundwater quality protection performance standards =et forth in the regulations is extremely short-sighted and contrary to public =ealth, groundwater resources and the protection of the environment. This =pproach has allowed the construction of municipal solid waste landfills that will =bviously not conform to the basic regulatory requirements of protecting =roundwaters from impaired use from waste associated constituents for as long as the waste =represent a threat.

Summary and Conclusions

Municipal solid waste and hazardous waste landfills of the type being =developed today in which either a single composite or a double =omposite-liner is used as a containment system for the wastes and collection system for =landfill leachate are likely and will ultimately lead to groundwater =ollution by leachate for those landfills sited at locations where there is a =ydraulic connection between the base of the landfill and groundwaters that are or =ould be used for domestic and other water supply purposes at any time in the =nfinite future. The failure of being able to specifically show groundwater =ollution by Subtitle C and D landfills today should not be interpreted to mean that groundwater pollution has not nor will not occur in the future. The =asic problem with such an approach is that the monitoring systems used to =etect landfill liner leakage involving vertical monitoring wells at the point =f compliance for groundwater pollution is a fundamentally flawed approach =hat has a low probability of detecting initial liner leakage before widespread groundwater pollution occurs.

Based on characteristics of the rate of movement of leachate through =he unsaturated and saturated zone, the characteristics of the liners and =he reliability of the groundwater monitoring systems that are being used =oday, it is concluded that it would be, indeed, rare that groundwater pollution =t the point of compliance for Subtitle C and D landfills would, in fact, be =etected today. These landfills have only been constructed for a relatively short =eriod of time. In many situations, the rate of migration of leachate through =he liner and subsurface strata would not be sufficiently great to be detected in monitoring wells that happen to intercept the finger plumes of leachate =hat are being generated or will be generated by leakage through the liner =ystem.

Ultimately, all Subtitle C and D landfills have the potential to =ollute groundwaters hydraulically connected to them. It is only a matter of =ime when this occurs. There is an urgent need to update RCRA to develop =egulatory approaches that will, in fact, protect groundwaters from pollution by =andfill leachate for as long as the wastes in a hazardous waste or municipal =olid waste landfill represent a threat. Until this update occurs, the siting of =andfills should be done in accord with reliably informing the regulatory agencies =nd the public that the current regulatory approach in developing Subtitle C and = landfills is not protective of public health, groundwater resources and =he environment from pollution by landfill leachate for as long as the =astes in the landfill represent a threat.


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Lee, G. F. and Jones, R. A., "Municipal Solid Waste Management in =ined, `Dry Tomb' Landfills: A Technologically Flawed Approach for Protection of =roundwater Quality," Report of G. Fred Lee & Associates, El Macero, CA, 68pp. =arch (1992).

Lee, G.F. and Jones-Lee, A., "The Cost of Groundwater Quality =rotection in Landfilling," Report of G. Fred Lee & Associates, El Macero, CA, =pp, July (1993a).

Lee, G. F. and Jones-Lee, A., "Geosynthetic Liner Systems for =unicipal Solid Waste Landfills: An Inadequate Technology for Protection of Groundwater Quality?" Waste Management & Research, 11(4):354-360 (1993b). =/P>

Lee, G. F. and Jones-Lee, A., "Landfill Post-Closure Care: Can Owners =Guarantee the Money Will Be There?", Solid Waste and Power, =U>7(4):35-39 (1993c).

Lee, G.F., and Jones-Lee, A., "A Groundwater Protection Strategy for =ined Landfills," Environmental Science & Technology, 28:584-5 =1994a).

Lee, G. F. and Jones-Lee, A., "Landfilling of Solid & Hazardous =aste: Facing Long-Term Liability," IN: Proceedings of the 1994 Federal Environmental Restoration III & Waste Minimization II Conference, =azardous Materials Control Resources Institute, Rockville, MD, pp. 1610-1618, =pril (1994b).

Lee, G.F. and Jones-Lee, A., "Recommended Design, Operation, Closure =nd Post-Closure Approaches for Municipal Solid Waste and Hazardous Waste Landfills," Report to Greenpeace, Mexico, G. Fred Lee and Associates, El =acero, CA (1995a).

Lee, G.F. and Jones-Lee, A., "Practical Environmental Ethics: Is =here an Obligation to Tell the Whole Truth?," Published in condensed form =Environmental Ethics: The Whole Truth" Civil Engineering, Forum, 65:6 (1995b). =/P>

Lee, G.F. and Jones-Lee, A., "Overview of Landfill Post Closure =ssues," Presented at American Society of Civil Engineers Convention session =evoted to "Landfill Closures - Environmental Protection and Land Recovery," San =iego, CA, October (1995c).

Parsons, A.M. and Davis, P.A., "A Proposed Strategy for Assessing =ompliance with the RCRA Ground Water Monitoring Regulations," Current Practices =n Ground Water and Vadose Zone Investigations, ASTM STP 1118, =avid M. Nielsen and Martin N. Sara, (editors), American Society for Testing and Materials, Philadelphia, PA (1992).

Sakti, J.P., Park, J.K., and Hoopes, J.A., "Permeation of Organic =hemicals through HDPE Geomembranes," In: Proceedings of ASCE National Environmental Engineering Conference, ASCE, New York, July (1991).

Tisinger, L.G., and Giroud, J.P., "The Durability of HDPE =eomembranes," Geotechnical Fabrics Report, p. 4-8, September (1993).

US EPA, "Solid Waste Disposal Facility Criteria; Proposed Rule," =ederal Register 53(168):33314-33422, 40 CFR Parts 257 and 258, US EPA, Washington, D.C., August 30, (1988a).

US EPA, "Criteria for Municipal Solid Waste Landfills," US EPA =ashington D.C., July (1988b).

References as:" Lee, G. F. and Jones-Lee, A., 'Detection of the =ailure of Landfill Liner Systems,' Report of G. Fred Lee & Associates, El =acero, CA, April (1996)."