The European criteria for acceptance of waste at landfills:
Implementation of Council Decision 2003/33/EC in Denmark
Ole Hjelmar11 Jesper Holm1, Jørgen G. Hansen2 and Kim Dahlstrøm2
DHI – Water & Environment
Agern Allé 5, DK-2970 Hørsholm, Denmark
1
2
Danish Environmental Protection Agency
Strandgade 29, DK- 1401 Copenhagen K, Denmark
Abstract
As part of the implementation of Council Decision 2003/33/EC the Danish EPA is developing the criteria for
acceptance of granular waste at landfills adjusted to Danish conditions. The Danish methodology is similar to
that used for the Council Decision criteria but the scenarios and conditions, particularly the water balances, are in
many respects different from those used in the general European case. In contrast to the Council Decision, the
Danish implementation will include development of leaching criteria for some organic components. It is also
planned to add an element of sustainability by limiting the necessary aftercare period. Since no results are
available yet, the paper focuses on describing the scenarios and conditions. It should be noted that the work
described is still in progress and that changes may still occur in the scenarios and preconditions.
Keywords: Landfill, Waste, Acceptance Criteria, Implementation, Leaching, Scenarios, Modelling, EU
Landfill Directive, Council Decision 2003/33/EC
1. Introduction
The Council Decision (2003/33/EC) of 19 December 2002 establishes criteria and procedures for the acceptance
of granular waste at landfills pursuant to Article 16 and Annex II of Directive 1999/31/EC on the landfill of
waste. The deadline for implementation of these criteria by the individual EU member states was 16 July 2004.
Due to the considerable amount of work involved, this deadline proved difficult to meet and the implementation
of the Council Decision has been somewhat delayed in several member states, including Denmark.
Since the Landfill Directive is a so-called minimum directive, the member states are allowed to set stricter
criteria nationally, if they can be justified by specific needs for protection of the environment. Denmark relies
almost exclusively on groundwater as a source of drinking water and therefore has a strong need for strict
protection of the groundwater quality. It is further Danish policy to promote sustainability in landfilling,
particularly in terms of limiting the duration of the necessary aftercare period at landfills. Whereas the concept of
sustainability has not been addressed in the EU Landfill Directive and the associated Council Decision, they do,
on the other hand, not prevent the pursuit of sustainability within the regulatory framework they define. The
Danish Environmental Protection Agency (DEPA) has therefore decided to use the methodology employed by
the “Modelling group” of the TAC Subcommittee for the Landfill Directive, adjusted to Danish conditions, to
develop the criteria to be implemented by Denmark, thereby attempting to ensure adequate protection of
groundwater and surface water bodies and to add an element of sustainability to landfilling. It is expected that
several of these criteria will be stricter than those listed in the Council Decision. Current Danish landfill policy
requires all new landfills to be located near the coast. This means that also protection of marine waters must be
taken into account. This will be incorporated into the development of Danish waste acceptance criteria but it will
not be addressed in this paper.

Author to whom correspondence should be addressed: oh@dhi.dk, phone: +45 45169405, fax: +45 45169292
This paper discusses the scenarios and the conditions applicable to the Danish situation with respect to the
development of leaching-based waste acceptance criteria. It was originally planned also to present the resulting
limit values to be implemented in Denmark. Due to the delay of the implementation procedure, this has not been
possible, and scenarios and other preconditions may still be subject to change. With some luck it should,
however, be possible to present at least proposals for Danish waste acceptance criteria at the time of the
WasteEng 2005 conference.
2. The Methodology
The methodology used to develop the acceptance criteria in the Council Decision 2003/33/EC has been
described in detail by Hjelmar et al. (2001), DHI and ECN (2003) and Hjelmar (2003). It is briefly summarised
below. Through a series of scenario-based model calculations a direct relationship is established between the
leaching behaviour of mainly inorganic contaminants released from landfilled granular waste, expressed in terms
of the results of a leaching test, and the risk these contaminants pose to the quality of downstream groundwater.
The approach may best be described in terms of a series of consecutive steps. First a decision is made concerning
the primary target or point of compliance (POC), e.g. the quality of groundwater at one or more points
downstream of the landfill. Quality criteria are then selected for the groundwater, and the physical characteristics
of the landfill and environment scenarios are selected and described. The environment scenario includes the net
rate of infiltration and a hydrogeological description of the unsaturated and saturated (aquifer) zones upstream,
below and downstream of the landfill. The source of the various contaminants is subsequently described in terms
of the flux of contaminants as a function of time (or the liquid to solid ratio, L/S) based on leaching data and the
hydraulic scenario defined. The leaching is approximated mathematically as an exponentially decreasing
function of L/S, using a component-specific constant, kappa () – see equation (1). Then the migration of the
contaminants from the base of the landfill through the unsaturated zone into the groundwater and through the
aquifer to the POC is modelled including only reversible, sorption-based contaminant/subsoil interaction
processes and using proven and accomplished flow and transport models. Selected Kd-values are used for each
contaminant to calculate and incorporate the retardation factors (assuming linear sorption isotherms). Based on
these “forward” calculations so-called “attenuation factors” (the ratio between the source peak concentration and
the peak concentration as modelled at the groundwater POC) are determined for each contaminant. The principle
of the three coupled source and transport models is illustrated in Figure 1.
Model 1: The source
POC
Model 2: Transport in
the unsaturated zone
Landfill
GWT
Model 3: Transport in the saturated zone
Figure 1. Cross-section showing the principle of three coupled source and transport models used for the forward impact
calculation at a landfill scenario.
The attenuation factors are then used for a “backwards” calculation of the permissible values of the source term
corresponding to the selected groundwater quality criteria for each contaminant at a particular POC. In the TAC
calculations the background concentration of the contaminants in the upstream groundwater was not taken into
account. The Danish calculations will include consideration of such background concentrations. The final step
consists of transforming the resulting source term criteria to a limit value for a specific test.
It should be noted that the procedure involves simplifications and generalisations of complex and diverse
physical-chemical processes. This may be justified by the need to have an operational and relatively simple
system, which can be used for the development of general criteria. If needed, it is always possible to apply other
or more sophisticated models and to adapt them to other general or site-specific conditions without changing the
principle of the calculations.
The Danish implementation of the Landfill Directive and the associated Council Decision will define four main
types of landfills: Inert waste landfills, hazardous waste landfills and two subcategories of non-hazardous waste
landfills, namely mineral waste landfills and landfills for mixed waste. Leaching criteria will be set only for
landfills for inert waste, mineral (non-hazardous) waste, and hazardous waste. A Danish mineral waste landfill
will in many respects be comparable to the landfills for non-hazardous waste receiving stable, non-reactive
hazardous waste as defined in the Council Decision.
3. Scenario and Calculation/Modelling Conditions
3.1 Selection of targets for protection and contaminants to be included
The TAC calculations only considered downstream groundwater quality, and the POCs were located 20 m and
200 m downstream of the edge of the landfill, respectively. In practice, only the POC located 20 m downstream
of the landfill was used for the setting of criteria. The Danish calculations will include both groundwater and
surface water quality targets. Because of the Danish policy of near-coastal location of landfills, marine water
quality will be an important target. However, as already mentioned above, only waste acceptance criteria based
on groundwater protection will be discussed in this context. The main Danish groundwater POC is placed 100 m
downstream of the landfill. For comparison with the criteria for utilisation of residues and soil, calculations are
also carried out for a POC located 30 m downstream of the landfill.
In the Council Decision, leaching-based criteria were set for As, Ba, Cd, Cr, Cu, Hg. Mo, Ni, Pb, Sb, Se, Zn,
chloride, fluoride, sulphate, DOC, phenol index, and TDS (as an alternative to chloride and sulphate) for waste
to be accepted at landfills for inert waste. For landfills for non-hazardous waste receiving stable, non-reactive
hazardous waste (from here on referred to as non-hazardous waste landfills) and landfills for hazardous waste,
leaching based criteria were set for the same components as for inert waste landfills with the exception of the
phenol index. In Denmark, the DEPA plans to include additional criteria for the leaching of those groups of
organics for which total content-based criteria have been set for acceptance at inert waste landfills in the Council
Decision. Those compounds are BTEX (in the calculations represented by benzene, toluene, and m-xylene), PCB
(in the calculations represented by PCB no. 28), mineral oil (only C10 to C25 are considered, in the calculations
represented by decane and pentadecane) and PAH (in the calculations represented by naphtalene and
fluroanthene).
3.2 Description of scenarios
The landfill scenarios used in the TAC calculations are shown in table 1, and the corresponding scenarios
specified for the Danish situation are presented in table 2. As can be seen, it is assumed that a typical Danish
landfill will be smaller than that anticipated by the TAC, both in terms of height, length and width. The general
net rate of infiltration is assumed to be 350 mm/year under Danish conditions as opposed to 300 mm/year for the
TAC calculations. In all cases, an active landfill operation period of 30 years is anticipated.
The hydraulic scenario for the Danish situation is quite different from that assumed by the TAC. This is mainly
due to the fact that in the Danish situation highly permeable top covers, which do not restrict the rate of
infiltration, are used for all three types of landfills, and that no collection of leachate takes place after the
artificial bottom liner ceases to function. The rate of infiltration of precipitation into all three types of landfills is
therefore assumed to remain constant at 350 mm/year in the DK calculations. The TAC calculations also assume
a highly permeable top cover for the inert waste landfills, and hence a constant rate of infiltration of 300
mm/year. In the case of non-hazardous and hazardous waste landfills the TAC calculations assume a reduced
rate of infiltration of 200 mm during the operation period (30 years). The top is then covered by a composite
liner (artificial liner and clay liner), which remains 100 % effective for 30 years. The artificial liner then
gradually deteriorates over the next 50 years, after which it has no effect. The clay liner remains effective, and
after 80 years it controls the rate of infiltration at 31.5 mm/year (corresponding to a permeability of 10-9 m/s at a
gradient of 1 m/m). The resulting assumed rates of infiltration are shown in table 3 for the TAC calculations and
in table 4 for the DK calculations.
Table 1. Description of landfill scenario conditions and assumptions used in the TAC calculations.
Parameter
Unit
Height of the landfill
Length of the landfill
Width of the landfill
Surface area
Volume
Porosity of the waste
Dry bulk density of the waste
Dry weight of the waste
Permeability of the waste
Hydraulic conductivity of top cover
m
m
m
m2
m3
t/m3
t
m/s
mm/år
Inert waste
landfill
20
150
150
22500
450000
0.3
1.5
675000
1 x 10-5
> 300
Type of bottom liner
Thickness of bottom liner (clay)
Permeability of clay bottom liner
m
m
m/s
none
-
Non-hazardous
waste landfill
20
200
200
40000
800000
0.3
1.5
1200000
1 x 10-5
variable:
(0-200)
composite*
1
1 x 10-9
Hazardous waste
landfill
20
200
200
40000
800000
0.3
1.5
1200000
1 x 10-5
variable:
(0-200)
composite*
5
1 x 10-9
*: composite bottom liner (artificial liner + clay liner)
Table 2. Description of landfill scenario conditions and assumptions used in the calculation under Danish
conditions.
m
m
m
m2
m3
t/m3
t
m/s
mm/år
Inert waste
landfill
10
100
100
10000
100000
0.3
1.5
150000
1 x 10-5
> 350
Mineral waste
landfill
10
100
100
10000
100000
0.3
1.5
150000
1 x 10-5
> 350
Hazardous
landfill
10
100
100
10000
100000
0.3
1.5
150000
1 x 10-5
> 350
m
m
m/s
composite*
2
1 x 10-7
composite*
2
1 x 10-9
composite*
5
1 x 10-9
Parameter
Unit
Height of the landfill
Length of the landfill
Width of the landfill
Surface area
Volume
Porosity of the waste
Dry bulk density of the waste
Dry weight of the waste
Permeability of the waste
Hydraulic conductivity of top cover
Type of bottom liner
Thickness of bottom liner (clay)
Permeability of clay bottom liner
waste
*: composite bottom liner (artificial liner + clay liner)
In the TAC calculations, it is assumed that an inert waste landfill has no bottom liner, and the rate of release of
leachate through the bottom of the landfill is hence 300 mm/year. Non-hazardous and hazardous landfills are
assumed to be equipped with a composite bottom liner, i.e. an artificial liner on top of a clay liner. The artificial
bottom liner is assumed to have an initial efficiency of 99 % and gradually deteriorate to an efficiency of 0 %
over a period of 200 years. The efficiency of the clay part of the bottom liner remains intact, corresponding to a
permeability of 10-9 m/s (or 31.5 mm/year at a gradient of 1 m/m), and after some time controls the rate of
release of leachate. It is assumed that the leachate which is not released through the bottom of the landfill, is
collected and managed (treatment and/or discharge). In fact, in the TAC calculations the collection and
management of leachate is assumed to continue for as long as it is deemed necessary, i.e. beyond 110 years.
Table 3. Assumed water balances over time for landfills for non-hazardous and hazardous waste in the TAC calculations
DHI & ECN (2003) and Dijkstra (2004).
years
Infiltration through top
cover
mm/year
Infiltration through
bottom liner
mm/year
Leachate to be collected and
treated and/or discharged
mm/year
0 –30
200
Increasing from 2 to 31.5
Decreasing from 198 to 168.5
30 – 60
0
0
0
60 –80
Gradually increasing from
0 to 200
Gradually increasing from 0
to 31.5
Period
80 – 110
31.5
Gradually increasing from 0 to
168.5
110 - 
200
31.5
168.5
Comment:
No cover during operation,
placement of artificial liner
after closure
Composite bottom liner. The
clay liner remains effective,
the artificial liner
deteriorates over 200 years
Continuing leachate collection
and management beyond 110
years assumed
Table 4. Assumed water balances over time for all three types of landfills in the Danish calculations.
years
Infiltration
through top cover
mm/year
0 –a
350
3.5
346.5
a-
350
350
0
Period
Infiltration through bottom
liner/over side
mm/year
Leachate to be collected and
treated and/or discharged
mm/year
Composite bottom liner. 99 %
effective during 70 years, then
Comment:
gradual deterioration of artificial
liner while overflow occurs
a: Time during which active leachate collection and management takes place. a = 60 years for inert waste
landfills, 80 years for mineral waste landfills and 100 years for hazardous waste landfills
No infiltrationreducing cover
In the Danish calculations, the hydraulic situation is the same for all three types of landfills, except for the
thickness and permeability of the bottom liner and the stipulated lifetime of the leachate collection system. All
landfills, including inert waste landfills, are equipped with composite liners. It is assumed that the artificial liner
remains 99 % efficient, corresponding to a rate of release of leachate through the bottom of 3.5 mm/year, for 70
years 60 years for inert waste landfills, for 80 years for mineral waste landfills and for 100 years for hazardous
waste landfills. After this period, the collection of leachate is assumed to stop (it is then required to have reached
a quality, which is acceptable in the surrounding environment) and a few years later all of the leachate produced
will flow over the edge of the liner unless other conduits are constructed. In the scenarios it is assumed that all
the leachate produced is released through the bottom or through or over the sides from year 60, 80 and 100,
respectively. The water balances for the Danish landfill scenarios are shown in table 4. The resulting relationship
between the liquid to solid ratio (L/S) and time is shown in table 5 for the different landfill scenarios for the first
100 years.
Table 5. Accumulated L/S as a function of time for the different landfill scenarios for the first 100 years.
Time elapsed
(years)
1
10
30
60
70
100
Danish scenarios, all
landfills
0.023
0.23
0.70
1.4
1.63
2.33
Accumulated L/S (l/kg)
TAC scenario for
TAC scenario for non-hazardous
inert waste landfill
and hazardous waste landfills
0.01
0.007
0.10
0.07
0.30
0.20
0.60
0.20
0.70
0.21
1.00
0.31
3.3 The composition of the leachate as a function of L/S
A rather crude and simplified description of the release of contaminants as a function of L/S or time is used in
both the TAC calculations and the Danish calculations. Waste/waste interactions are neglected and the landfill is
regarded as one large column or lysimeter, and it is assumed that the leaching of the contaminants under
consideration can be described as an exponentially decreasing function of L/S or time, originally based on a
simple continuously stirred tank reactor model (see e.g. Hjelmar et al., 2001). The concentration C of a
contaminant in the leachate (or eluate, from a laboratory leaching test) may then be estimated as follows:
C = C0 x e-(L/S) 
where
(1)
C0 is the initial peak concentration of the contaminant in the leachate (mg/l),
L/S is the accumulated liquid to solid ratio corresponding to the concentration C (l/kg),
 is a kinetic constant describing the rate of decrease of the concentration as a function of L/S for a given
material and a given component (kg/l).  may be estimated from laboratory leaching data and is for this purpose
considered independent of the material/waste in question (this is not actually true as  may vary both with
material and L/S, and the description of the source term may be improved by using material-specific  values
over limited L/S ranges).
By integrating the above expression, the amount of contaminant, E (in mg/kg), released over the period of time it
takes for L/S to increase from 0 l/kg to the value corresponding to C, can be calculated:
E = (C0/)(1 – e - (L/S) )
(2)
Only a limited number of determinations of  are available, and the values used for the inorganic contaminants
both in the TAC calculations and the Danish calculations were produced by Albers et al. (1996) based on column
leaching tests performed on construction materials. Additional data on phenol and DOC were estimated by ECN
(DHI and ECN, 2003). The values are listed in table 6. Improved  values adjusted to specific groups of waste
and scenarios may, if possible, be applied in the Danish calculations.
Leaching curves (C/C0 vs. L/S) for various values of , assuming the CSTR leaching model, are presented in
figure 2.
Since no  values are available for organic compounds (other than phenol and DOC), values have been estimated
partly on the basis of theoretical considerations, assuming that the CSTR leaching model is applicable also to
organic compounds. It was further assumed that the waste types (inert, non-hazardous and hazardous) may be
represented by soils with different contents of TOC (same value used for non-hazardous and hazardous waste).
Fugacity calculations for a given compound were then performed for a system under conditions corresponding to
those in the unsaturated zone. The starting point was saturated pore water, and the distribution between the
water, solid and gas phases was subsequently determined using K d values estimated from TOC and literature
values of KOC (the organic carbon/water partitioning coefficient) estimated from the octanol/water partitioning
coefficient (KOW), water solubility and Henry’s constant. Pore volume distributions of air and water, V A/Vw,
corresponding to 2 (sand) and 0.33 (clay), respectively, were used. The resulting  values are shown in table 7.
Table 6. List of the  values for inorganic components and phenol and DOC used both in the TAC calculations
and the Danish calculations.
Parameter
As
Ba
Cd
Cr
Cu
Hg
Mo
Ni
Pb
Sb
Se
Zn
Chloride
Fluoride
Sulphate
Phenol
DOC
Average values and 95 %
confidence intervals for  (kg/l)
0.03  0.05
0.15  0.04
0.50  0.10
0.18  0.03
0.28  0.03
0.05  0.03
0.35  0.04
0.29 0.05
0.27 0.06
0.11  0.07
0.38  0.18
0.28  0.05
0.57  0.07
0.22  0.14
0.33 0.05
0.3
0.17
Number of
determinations
44
55
37
82
90
5
76
37
52
33
10
41
45
6
49
Data source
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
Albers et al. (1996)
ECN (DHI &ECN, 2003)
ECN (DHI &ECN, 2003)
Kappa (kg/l)
0.1
0.2
0.5
0.8
1
5
10
1
0.8
C/C0
0.6
0.4
0.2
0
0.001
0.01
0.1
1
10
100
L/S (l/kg)
Figure 2. The influence of  on the shape of the leaching curve, assuming the CSTR leaching model.
The calculations were repeated in steps corresponding to the annual rate of infiltration and accounting for the
gradual removal of organic contaminant with the pore water to provide C/C 0 as a function of L/S from which 
could subsequently be determined. Assuming values of fOC for inert waste (fOC = 0.005), mineral waste (fOC =
0.03) and hazardous waste (fOC = 0.03), the  values shown in table 7 were calculated for the organic compounds
under consideration for use in the model calculations (it is still being considered whether to use one  value for
all waste types or whether to use two different  values for each component as calculated). Only  values
corresponding to clay properties are shown since they were lower than or equal to those corresponding to sand
properties and hence considered most critical in relation to the model calculations. As shown in Figure 2, a lower
 corresponds to a slower decrease in leachate concentration, and this generally leads to a higher downstream
peak groundwater concentration).
Table 7. Estimated values of  (in kg/l) for organic compounds leaching from waste in Danish scenarios.
Compound
Benzene
Toluene
m-xylene
Naphtalene
Fluoranthene
Decane
Pentadecane
PCB 28
Inert waste
(fOC = 0.005)
3.8
1.6
0.74
0.42
0.0052
0.00043
0.0000015
0.0020
Mineral waste
(fOC = 0.03)
1.2
0.34
0.14
0.073
0.00086
0.000073
0.00000024
0.00033
Hazardous waste
(fOC = 0.03)
1.2
0.34
0.14
0.073
0.00086
0.000073
0.00000024
0.00033
3.4 Transport and groundwater quality parameters
Table 8 shows the values of Kd used to describe the contaminant/subsoil interaction in the transport modelling
both in the TAC calculations and in the Danish calculations (still subject to change). The same Kd values are
used to describe the conditions in the both the unsaturated and the saturated zones.
Table 8. Subsoil Kd values (both for the unsaturated and saturated zones), groundwater background concentrations and GW
criteria used in the TAC calculations (DHI and ECN, 2003) and proposed for the Danish calculations. The Danish
Kd values are still under consideration.
Component
As
Ba
Cd
Cr
Cu
Hg
Mo
Ni
Pb
Sb
Se
Zn
Chloride
Fluoride
Sulphate
Phenol
DOC
Benzene
Toluene
m-xylene
Napthalene
Fluoranthene
Decane +Pentadecane
PCB 28
DK
100
2
20
1
100
20
10
20
100
5
5
20
0
2
0
5
0
0.02
0.1
0.2
0.5
40
100
100
Kd
(l/kg)
TAC
50
2
20
100
14
1
10
50
50
5
5
30
0
2
0
40
0
-
GW background conc.
(g/l)
DK only
0.8
62
0.008
0.09
0.3
0.0011
0.7
0.5
0.05
0.08
0.10
3.0
25
0.5
50
0
Undetermined
0
0
0
0
0
0
0
GW quality criteria at POC
(g/l)
DK
TAC
8
10
700
700
2
4
20
50
100
50
1
1
20
70
10
20
5
10
2
5
10
10
100
100
150000
250000
1500
1500
250000
250000
Undetermined
100
3000
10000
1
5
5
1
0.1
5
-0.01
-
In the Danish calculations, the background concentration of the contaminants in the upstream groundwater are
taken into account in the determination of the dilution. The background concentrations used are also shown in
table 8. The table also shows the groundwater quality criteria set at the POC in both cases. Substantial reductions
are seen in the Danish values as compared to the TAC values for Hg, Mo and phenol. Smaller reductions are
seen for As, Cd, Cr, Ni, Pb, Sb and chloride, whereas an increase is seen for Cu.
3.5
Transport modelling in the unsaturated and saturated zones
The input to the transport model for the unsaturated zone in terms the flux of each contaminant as a function of
time is calculated for each type of landfill by combining the information on the flow of leachate out of the
landfill (section 3.2) with the information on the composition of the leachate as a function of L/S (section 3.3).
For a given scenario, the relationship between L/S and time is easily calculated (e.g. Hjelmar, 1990).
A numerical 3 D flow and transport code, MIKE-SHE, in which the modelling of the transport through the
unsaturated and the saturated zones is integrated, is applied in the Danish contaminant transport calculations
(DHI, 2003). The corresponding TAC calculations were performed using CXTFIT/ECOSAT and HYDRUS 2D
for the unsaturated zone and MODFLOW and MT3D for the saturated zone (DHI and ECN, 2003).
Since the clay part of the bottom liners under the landfills constitutes the unsaturated zone, the parameter values
for the unsaturated zone modelling can be seen in tables 1 and 2. The parameter values used in the model
calculations of the transport in the saturated zone both in the Danish and the TAC calculations are shown in table
9.
The relatively large differences between the DK and TAC dispersivities may be explained by the fact that in the
TAC calculations, high dispersivities were used in the model to ensure the occurrence of total vertical mixing in
the aquifer, which was one of the pre-conditions. Total vertical mixing is not assumed in the Danish calculations.
Table 9. Parameter values used in the model calculations of transport in the saturated zone in the Danish calculations and
in the calculations performed by the TAC (DHI and ECN, 2003).
Parameter
Width of catchment
Length of catchment
Distance from water divide to beginning of landfill
Distance to POC
Net rate of infiltration
Thickness of aquifer
Upper boundary
Fixed hydraulic head at downstream boundary
Horizontal hydraulic conductivity Kx = Ky
Vertical hydraulic conductivity Kz
Effective porosity
Longitudinal dispersivity
Transversal dispersivity
Vertical dispersivity
Cell size
Number of calculation layers
Unit
Used in DK
m
m
m
m
mm/year
m
m
m/s
m/s
m
m
m
m
-
300
250
50
100 (and 30)
350
6
Closed
Approx. 5.75
10-4
10-5
0.3
0.45
0.001
0.0005
2
8
Used by
TAC
500
600
100
20 and 200
300
Approx. 6
Closed
Approx. 4.1
1.4 x 10-4
1.4 x 10-4
0.3
20
4
2
10
6
4. Determination of Attenuation Factors and Limit Values for Leaching
Once the attenuation factor (i.e. the ratio between the peak concentration at the bottom of the landfill and the
peak concentration at the POC) has been determined for a given contaminant and a given landfill scenario, it can
be used to determine the maximum allowable concentration at the base of the landfill. In the TAC calculations,
the maximum allowable concentration is found by multiplying the groundwater quality criteria (table 8) by the
attenuation factor. In the Danish calculations, where background concentrations are accounted for, the upstream
background concentration (table 8) is subtracted from the groundwater quality criteria before it is multiplied by
the attenuation factor.
To find the actual leaching limit value in terms of released amount (mg/kg), the maximum allowable
concentration found above is entered into equation (2) in section 3.3 as C0. Using the appropriate values for L/S
and  (see Tables 6 and 7), the limit value E corresponding to the L/S value used can be calculated. Denmark has
chosen to refer the limit values to L/S = 2 l/kg and to use the batch leaching test EN 12457-1 for compliance
purposes.
Due to the delayed implementation of the Council Decision in Denmark, actual modelling results and limit
values are not yet available. They should, however, be available for presentation at the time of the WasteEng
2005 conference.
5. Conclusion
As part of the implementation of the Council Decision 2003/33/EC the Danish EPA has decided to use the
methodology employed by the “Modelling group” of the TAC Subcommittee for the Landfill Directive, adjusted
to Danish conditions, to develop the waste acceptance criteria to be applied in Denmark. Due to the strong
emphasis on groundwater protection in Denmark, some of the Danish acceptance criteria are expected to be more
stringent than those developed by the TAC. Since the Danish implementation of the Council Decision has been
delayed, actual results of the model calculations are not yet available. Instead, the paper focuses on describing
the scenarios and conditions, which are being used in the Danish model calculations. Throughout, they are
compared to the scenarios and conditions used in the TAC calculations.
Some of the major differences are that a bottom liner for inert waste landfills is prescribed in DK but not by the
TAC, and that in contrast to the TAC calculations, no infiltration-reducing top cover is allowed at the Danish
landfills. It is furthermore assumed that leachate collection is discontinued for the three landfill types defined in
DK (for inert waste, mineral, non-hazardous waste and hazardous waste, respectively) after 60, 80 and 100 years,
respectively, at that time producing an overflow of 350 mm/year and requiring the leachate to be acceptable in
the surrounding environment. In principle, leachate collection is continued forever for the TAC calculation
scenarios for non-hazardous and hazardous waste, producing an annual release of leachate of only 31.5 mm.
Another difference is that DK intends to develop leaching criteria for those organic components (BTEX, PCB,
mineral oil and PAH) for which total content criteria are required for inert waste landfills in the Council
Decision. The Danish POC is located 100 m downstream of the landfill, whereas the TAC in the POC
calculations were placed 20 m downstream for most components. In addition, several parameters used in the
release and transport calculations, including Kd values, groundwater background concentrations and groundwater
quality criteria have been adjusted to Danish conditions. Both the kappa-values used in the source term and the
Kd values are still under consideration. The resulting limit values may be expected to differ from the TAC
results.
6. Acknowledgement and Disclaimer
The work presented in this paper was funded by the Danish Environmental Protection Agency (DEPA) and
based on the methodology developed by the Model Group under the TAC Subcommittee for the Landfill
Directive, which developed the criteria for acceptance of waste at landfills described in Council Decision
2003/33/EC. As in several other countries, the implementation of the Council Decision into Danish legislation
has been delayed, and the iterative process of setting up and adjusting scenarios and conditions and performing
model calculations has not yet been fully completed. The work and the data presented must therefore be regarded
as preliminary and subject to change.
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