HYDRAULIC ESTIMATION OF DRAINAGE DISCHARGE RATE AT SANITARY LANDFILL OF COMMUNAL WASTE IN OSECNA, NORTHERN BOHEMIA[1]

 

 

Ing. Jakub Stibinger, Ph.D.[2], and Ing. Mojmír Soukup, Ph.D. [3]

 

 

 

ABSTRACT

This paper describes the method of hydraulic calculations of the drainage discharge rate from the internal landfill drainage system, placed at the bottom of the sanitary communal waste landfill, based on the drainage theory of De Zeeuw-Hellinga, under the non-steady saturated drainage flow conditions. The results were verified and compared with the actual data measured in the sanitary landfill of domestic waste in Osecna location, situated in Northern Bohemia, Czech Republic.

 

Keywords: Drainage, Leakage, Drainage Discharge Rate, Landfill, Communal and Domestic Waste, Sanitary Landfill.

 

 

1                    INTRODUCTION

The drainage system at the bottom of the landfills of the communal and domestic waste are used  to  secure conservation of the environment. The design of drainage system placed at the bottom of the sanitary landfills of communal waste should proceed from a water management project based on mathematical and physical description of the hydraulic processes inside the landfill body (Stibinger, 1994), hydrological conditions of the particular locality, the amount and physical properties of incoming communal and domestic waste as well as on the way of landfilling.

 

The hydraulic calculations of the landfill leakage rate, resp. drainage discharge rate from the internal landfill drainage system, placed at the bottom of the sanitary communal and domestic waste landfill, are, in this case, based on the drainage theory of De Zeeuw-Hellinga, under non-steady saturated drainage flow conditions (Ritzema, 1994). The results were verified and compared by the actual data from the sanitary landfill of domestic waste in Osecna location, situated in Northern Bohemia.

 

 

2                    THEORETICAL

 

2.1               De Zeeuw-Hellinga Equation

To simulate the drainage rate, in this case the landfill leakage rate q (M/T), during a period with a non-uniform distribution of landfill recharge R (M), the period was divided into time intervals of equal length (day, month, year).

 

De Zeeuw and Hellinga discovered that the change in the drainage rate is proportional to the excess drainage rate (R-q) (M/T) if the recharge R (M) in each time-interval is assumed to be constant. De Zeeuw-Hellinga drainage intensity factor a (T-1) represents the constant of proportionality and depends on the parameters of pipe drainage system and on the position of the impervious layer (Dieleman and Trafford, 1976).

 

In this case, drainage intensity factors also express the hydraulic efficiency of the landfill internal drainage system, which is situated at the bottom of landfill body. The basic equation can be formed as:

                                                                                                                              (1)

After integration between the limits t=t , q=q1 and t=t-1 , q=qt-1 can be written:

                                                                                                         (2)

where:

q                           landfill drainage discharge rate (M/T)

                       change in the landfill drainage discharge rate (M/T)

qt, qt-1                      landfill drainage discharge rate in time-interval t, t-1 (M/T)

      time interval (T)

R                          recharge of percolation water of landfill, constant in time interval (M) 

A                          De Zeeuw-Hellinga drainage intensity factor (T-1)

t                            time (T)

M, T                      length, time unit

 

2.2        Water balance equation for landfills

The recharge of the percolation water of landfill R (M) to the internal drainage system at the bottom of the landfill body, can be derived from the series of the cumulative values of recharges  (M), which was constructed by help of the simplified water balance equation, formed as:

                                                                               (3)

where:

i                            interval in the tested period

n                           total number of intervals in the tested period

                    series of the cumulative values of recharges in tested period (M)

                   series of the total precipitation amounts in tested period (M)

                    series of the total landfill irrigation amounts in the tested period (M)

                   series of the total landfill evaporation amounts in tested period (M)

                   series of the total quantity of the landfill surface run-off in tested period (M)

V.               series of the total wastewater retention capacity amounts in tested periods (M)

V                          water storage capacity or drainable pore space of the domestic waste (%

of volume)

Parameter W (M) represents the amount of waste in length units and can be approximated by expression W = (N.G-1) / S where N is the amount of waste in tons, G represents the density of waste in ton per volume and S (M2) is area delimited for waste landfilling. Because the series of the cumulative values of recharges (M) represents in reality cumulative curve, the values of the recharges of the percolation water of landfill R (M) for individual corresponding time interval  (  ) can be derived  by equation (4).

 (M)                                                                                                                             (4)

If the expression the R = 0. From the known values of the recharges R (M) and by the application of the De Zeeuw-Hellinga drainage theory, the landfill leakage rate (M/T) was estimated according to equation (4) in the each time interval .

 

 

3                    EXPERIMENTAL STUDY OF THE LANDFILL

 

3.1               Elemental input data of the landfill Osecna

All the data, which are necessary for calculation of the parameters of equation (3), (4) and for an approximation of the De Zeeuw-Hellinga drainage intensity factor a (T-1) and finally for the estimation of the landfill leakage rate  (M/T) according to equation (2), were taken from the monthly hydrological records of the location Osecna, region Liberec and from the landfill Osecna working records (monthly data) and from the monitoring of the landfill Osecna. In accordance with the De Zeeuw-Hellinga drainage theory, it is assumed, that all values in a selected time-interval (month) are constant.

 

The sanitary landfill of the solid domestic waste Osecna, situated near the location Osecna, region Liberec, Northern Bohemia, opened running in December 1995. It is supposed the landfill running will be finished at the end of the year 2003. The landfill location is situated in the Luzicke Mountains with altitude 770 – 800 meters above the sea level, in the forested territory of the Sierra Ještěd base. Long-term annual average of precipitation amounts to 910 mm, long-term annual average of temperature amounts to about 7.3.

 

The effective area S (M2), delimited for waste landfilling during the years 1997 and 1998, amounted to about 2.14 hectares (21 400 m2). The landfill internal drainage system, placed at the bottom of landfill body, comprises the drain spacing L (m) = 30, average of the thickness of the gravel drainage layer D (m) = 0.3 and diameter of the lateral drains r0 (m) = 0.1. Plastic perforated drainage pipes are placed under the drainage layer on the approximately horizontal landfill base liner. Hydraulic saturated conductivity of the gravel-sand material of drainage layer K= 3.0 m. day-1, drainable pore space Pd = 0.25 (-), (Figure 1).

 

The results of the initial hydraulic calculations indicate the value of the average depth of aquifer H (m) = 0.14 (lateral drains are placed almost to an impervious sealing system), and indicate the value of the De Zeeuw-Hellinga drainage intensity factor a (day-1) = (2K./ (L2.Pd) = 0.0184.

 

The base liner of the sanitary landfill Osecna is approximately horizontal. The slope of the base with plastic sealing foil is neglected. This fact is corresponding with premises of the De Zeeuw-Hellinga drainage theory, which is based, besides others, on a present of the approximately horizontal impervious layer. In a case of the strongly sloped landfill base liner system, other models and other methods have to be applied (D’Antonio and Pirozzi, 1991, McEnroe, 1992, Upadhyaya and Chauhan, 2001).

 

3.2               Results of hydraulic calculations

For description of the hydraulic behaviour of leakage at the bottom of sanitary landfill Osecna by De Zeeuw-Hellinga drainage theory was chosen year 1998, the third year of the landfill running. The actual hydrological and working data from landfill Osecna during the year 1998 are presented in Table 1 and viewed on Figure 2.

Figure 1   A scheme of the internal landfill drainage system inclusive of the drainage discharge and recharge processes at the Landfill Osecna, Northern Bohemia, Czech Republic, 1998

 

The water storage capacity V (% of volume) of the domestic waste and the waste density G (ton.m-3) in the conditions of the landfill Osecna, were approximated by the field experimental measurement, laboratory testing (Kutílek and Nielsen, 1994, Genuchten and Nielsen, 1985) and from the landfill working records as V (% of volume) = 25.0 and G  (ton.m-3)  =  0.85.

 

The specific hydrological conditions of the territory of the Sierra Ještěd base, the way of landfilling of the communal waste and the handling of percolation waters from landfill (landfill irrigation) in the landfill Osecna, allowed to reduced the water balance equation (3) in the tested period in to following form:

                                                                                                         (5)

 

By the reduced water balance equation (5), the cumulative values of the landfill recharges (mm) from the landfill Osecna, which in reality form cumulative curve (see Table 2) were approximated. In Table 2 are also presented the cumulative values of precipitation, total amounts of the incoming domestic waste and cumulative values of the waste water retention capacity (see Figure 3). All these data create the input parameters of the reduced water balance equation (5) for approximation of the cumulative values of the landfill recharges.

 

On the basis of known constant values of the landfill recharge curve R (mm) in the monthly time interval (see Figure 3 and Table 3) and the known value of the De Zeeuw-Hellinga drainage intensity factor a (day-1) = (2K./ (L2.Pd) = 0.0184 = 0.552 (month-1), according to equation (2), the values of the drainage discharge rate qt (mm/month) for every month (time-interval t) of the year 1998, were calculated. In accordance with De Zeeuw-Hellinga drainage theory, it is supposed, that the drainage discharge rate in the corresponding time interval (month) will be constant.

 

Table 1   Measured characteristics from the landfill Osecna (solid communal waste), location Osecna, Northern Bohemia, 1998.

1998 (month)

 Precipitation     (mm)

  Solid waste

 (tons)

 Leakage

 (mm)

  1 

 54.0

  15 014

   4.5

  2

 53.5

  11 718

 13.0

  3

102.0

  17 162

 24.0

  4

 19.5

  23 815

 15.0

  5

 22.5

  23 626

   5.6

  6

 73.0

  23 758

   4.0

  7

 69.0

104 138

   9.0

  8

 36.5

  23 266

   2.3

  9

100.0

  21 405

 32.5

 10

 80.3

  18 457

 25.4

 11

 66.1

  17 823

 26.6

 12

 24.4

  12 924

   2.3

Total

700.8

313 100

164.2  

 

Figure 2   Measured data from the landfill Osecna (solid waste), Northern Bohemia, 1998.

Table 2   Measured and calculated cumulative values from the landfill Osecna, Northern Bohemia, 1998 (*  measured values,  +   calculated values)

cumulative values

from 12. 1995 to

precipitation

(mm)    *

Communal

waste

(tons)    *

wastewater

retention

(mm)     +

Landfill

recharge

(mm)     +

               1997

1640.0

118313.6

1626.0

  13.9

1998 (month) 1

1694.0

119815.0

1646.7

  47.2

                 2

1747.5

120986.8

1662.8

  84.6

                 3

1849.5

122703.1

1686.4

163.0

                 4

1869.0

125084.6

1719.1

149.8

                 5

1891.5

127447.2

1751.6

139.8

                 6

1964.5

129823.0

1784.2

180.2

                 7

2033.5

140236.8

1927.3

106.1

                 8

2070.0

142563.5

1959.3

110.6

                 9

2170.0

144704.0

1988.7

181.2

               10

2250.3

146549.8

2014.1

236.1

               11

2316.4

148332.1

2038.6

277.7

              12

2340.8

149624.5

2056.4

284.3

 

If, for example, q6 = 26.5 (mm/month), it means, that the total landfill leakage in the June (at 1 month) will be 26.5 mm. The calculated values of the landfill leakage qt are expressed in mm per corresponding month (time-interval t). The results of the estimations (together with actual monthly measured values of the landfill leakage) are presented in Table 3 and graphically demonstrated in Figure 4.

 

The values of the recharges of the landfill percolation water R (mm) in the corresponding time intervals with constant length (months) were derived according to equation (4). The results, landfill recharge curve R (mm), are graphically symbolized in Figure 3 and presented in Table

 

 

4                    RESULTS AND DISSCUSION

From the comparison of monthly values of the landfill leachate qt calculated according to equation (2) for the landfill Osecna conditions and the factual measured monthly values of the landfill leakage from the same field (see Figure 4 and Table 3) it is obvious, that the shape of the curve of equations (2) and the shape of the curve of the actual measured monthly values is identical, even though the certain difference between the curves is apparent.

 

It seems that the maximum difference affects at the maximum of the precipitation. It means, that the De Zeeuv-Hellinga drainage model reacts for precipitation much more better then for an incoming amount of domestic waste, which creates the wastewater retention capacity of the landfill body and reduces the direct precipitation effects.

 

The use of the De Zeeuv-Hellinga way of estimation will be probably more effective at the beginning of landfilling, where the impact of precipitation is strong and the landfills are, especially in this period, more unstable during the precipitation and heavy rains action. De Zeeuv-Hellinga drainage theory also supposes, the relatively large distance between drain pipe level and impervious layer and this requirement, in a case of the landfill Osecna, was not completely carried out.

 

On the other hand, it should be noted that the modeling of time series of the landfill leakage during the landfilling is very difficult and complicated. The mathematical and physical description of the incoming waste compacting and increasing in connection with hydrological processes can be exact, especially for a long period of landfilling.

 

And from this point of view, the De Zeeuv-Hellinga drainage model can be applied as a suitable tool for landfill leakage approximation in a certain selected (critical) time period of the landfilling. It also appears, that the De Zeeuv-Hellinga drainage model approximation, yields the slightly higher values of the landfill leachates then the experimental data, so that is why, the application of its results, can guarantee the more effective probability of the internal landfill drainage system design.

Figure 3   Total amounts of precipitation, incoming waste and total values of wastewater retention capacity with course of the landfill recharge R, Landfill Osecna, Northern Bohemia, 1998.

Table 3   Landfill recharge monthly values and landfill leachate measured and calculated monthly values from the landfill Osecna, (solid communal and domestic waste), Northern Bohemia, 1998

1998 (month)

Precipitation

(mm)

Landfill

recharge

R (mm)

Landfill leakage measured values (mm)

Landfill leakage qt,  calculated

values (mm)

 1

  54.0

 33.4

   4.5

 20.0

 2

  53.5

 37.4

 13.0

 27.4

 3

102.0

 78.4

 24.0

 49.1

 4

  19.5

   0.0

 15.0

 28.2

 5

  22.5

   0.0

   5.6

 16.2

 6

  73.0

 40.3

   4.0

 26.5

 7

  69.0

   0.0

   9.0

 15.2

 8

  36.5

   4.5

   2.3

 10.7

 9

100.0

 70.6

 32.5

 36.2

10

  80.3

 55.0

 25.4

 44.2

11

  66.1

 41.6

 26.6

 42.8

12

  24.4

   6.6

   2.3

 27.4

Total

700.8

367.8

164.2

343.9 

Figure 4   Comparison between the measured and calculated values of the landfill leakage Landfill Osecna, Northern Bohemia, 1989.

 

 

5                    CONCLUSIONS

The correct estimation of landfill drainage recharge rate during the landfilling has a key role in landfill hydrology and landfill drainage policy. It is vital for the impact evaluation of the existing internal landfill drainage systems or for the calculation of parameters of the new ones.

 

Verification of simple analytical De Zeeuv-Hellinga solution as application to estimate the landfill drainage recharge from the internal drainage landfill system at the bottom of landfill, formed in equation (1) and (2), showed a good conformity between calculations and measured data under the unsteady state saturated landfill drainage flow (leakage) in the bottom of landfill body.

 

At the Department of Land Use and Improvement, Faculty of Forestry, Czech University of Agricultural Prague, research of the landfill leakage at the beginning of landfilling is carried out. The partial results of this investigation entitle to apply the De Zeeuv-Hellinga drainage model of landfill leakage, expressed by equation (2), especially in the initial period of the landfilling on conditions that the complex software products like DRAINMOD (Skaggs, 1999), SWAP (Dam, 2000), MODFLOW are used, or the other available models of similar type should be tested or adjusted for the landfill hydrology. This introduced De Zeeuv-Hellinga landfill leakage approximation should be used as a simple tool for immediate estimation of the values of landfill leakage for certain selected time intervals, further can be corrected and specified. It should serve as a tool what requires only minimum amount of information (the basic  hydrology data, working data of the waste collecting and landfill bottom drainage system basic design parameters).

 

The verification of the field test results and measurements reflects, that the possibilities of application and their benefits user, mentioned above, can be fulfilled.

 

 

6                    ACKNOWLEDGEMENTS

The authors thank Mrs. Jiřina Suvova for her careful documentation of all data. We would like to acknowledge in particular help of Mrs. Marta Medlikova from GESTA Rynoltice a. s., Landfill Osecna, during the operation on the landfill site Osecna.

 

 

7                    REFERENCES

Dam J. C. van, (2000) Field-scale water flow and solute transport. SWAP model concepts, parameter estimation and case studies. Doctoral Thesis Wageningen University. Wageningen, The Netherlands, (pp. 5-26).

D’Antonio G., Pirozzi F. (1991) Hydraulic behaviour of leachate at the bottom of sanitary landfills. Proceedings Sardinia 91, Third International Landfill Symposium, CISA publisher, Cagliari, vol. II, 899-997. 

Dieleman P. J., Trafford B. D. (1976) Drainage testing. Irrigation and Drainage Paper 28. FAO. Rome, Italy, (pp. 58 – 62).

Genuchten M. Th. Van, Nielsen D. R. (1985) On describing and predicting the hydraulic properties of unsaturated soils. Annales Geophysicae 3. pp. 615-628.

Kutílek M., Nielsen D. R. (1994) Soil hydrology. Geo-ecology textbook, Catena Verlag, 38162 Cremlingen Destedt, Germany. ISBN 3-923381-26-3, pp. 98-102.

McEnroe B. M. (1992) Hydraulics of leachate collection and cover drainage. In  Landfilling of Waste: Leachate, Christensen, Cossu, Stegmann (Eds), Elsevier Applied Science Publisher, London and New York, pp. 531-541.

Ritzema H. P. (1994) Subsurface flows to drains. In: Drainage Principles and Applications, H. P. Ritzema (Eds),ILRI Publ. 16, Wageningen, The Netherlands. (pp. 283-294).

Stibinger J. (1994) Design Parameters of Landfill Internal Drainage System. Proceedings EIPOS 94, International EIPOS-Conference, TU Dresden, Dresden, Germany, pp. 355-358.

Skaggs R. W. (1999) Drainage simulation models. In: Agricultural Drainage, R. W. Skaggs & J. Schilfgaarde van, American Society of Agronomy, Inc., Crop Science Society of America, Inc., Soil Science Society of America, Inc., Madison, Wisconsin, USA, (pp 469-500).

Upadhyaya A. and Chauhan H. S. (2001) Falling water tables in horizontal / sloping aquifer. Journal of Irrigation and  Drainage Engineering. Vol. 127, No. 6. ASCE, ISSN 0733-9437, pp. 378-384.

Non-published papers of the GESTA Rynoltice a. s. of the hydrologic and landfill data from sanitary landfill of domestic waste in Osecna location, region Liberec,  /Northern Bohemia/, Czech Republic, 2001 /in Czech/

CSN standard 83 80 33. (2002) Landfilling of waste – Handling of percolation water from landfills, Prague, Czech Republic

CSN standard 83 80 30. (2002) Waste landfilling - Basic conditions for design and construction of landlfills, Prague, Czech Republic


[1]         Paper No 045. Presented at the 9th International Drainage Workshop, September 10 – 13, 2003, Utrecht, The Netherlands.

[2]         Department of Land Use and Improvement, Faculty of Forestry, Czech University of Agricultural Prague, 165 21 Prague-6, Kamycka 129, Czech Republic, e-mail: stibic@email.cz

[3]         Research Institute for Soil and Water Conservation Prague, 156 27 Prague-5, Zabovreska 250, Czech Republic, e mail: soukup@vumop.cz.