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All the examples in this appendix have been stored in the Examples project. When reviewing these examples, you can either use the models in the Examples project or create a new project and create the models using the New Model button. In the examples below, it is assumed that the models in the Examples project are being used.

 

Case 1

 

This example shows how to create a Subtitle D landfill with a composite liner and constant concentration source. The flow through the composite liner is calculated using a leakage rate calculation as proposed by Giroud et. al. (1992).

 

Case 2

 

This example shows the case of pure diffusion with constant source and base concentrations.

 

Case 3

 

This example edits the previously entered data in Case 2 to include advective transport and fixed outflow in the base stratum.

 

Case 4

 

This example shows how to add a finite mass source with leachate collection to Case 3. Also shows how to calculate the Reference Height of Leachate and the Volume of Leachate Collected. Uses the automatic search for the peak concentration.

 

Case 5

 

This example illustrates use of the program to model a hydraulic trap, using essentially the same data as in Case 4.

 

Case 6

 

This example has a 1 m thick compacted clay liner underlain by a 3 m thick fractured till layer. The source is finite mass with a leachate collection system, and the base is an aquifer with fixed outflow. Different sorption in the liner and the fractured till isalso considered.

 

Case 7

 

In this example the lateral migration of a radioactive contaminant is modelled, in a fractured porous rock with a single set of parallel fractures. The base of the porous rock is assumed to extend to a considerable distance from the source and is represented by an infinite thickness boundary condition. This example illustrates the case where the default integration is not adequate. The maximum sublayer thickness feature is also used in this example.

 

Case 8

 

This examples uses an Initial Concentration Profile in analyzing a laboratory diffusion test for Potassium. The specimen consists of a 4.5 cm thick clay sample with a background concentration of Potassium of 10 mg/L. In this example the Reference Height of Leachate is equal to the actual height of leachate above the sample.

 

Case 9

 

Freundlich non-linear sorption is considered in analyzing a laboratory diffusion test for Phenol in this example. The sample is a 7 cm thick undisturbed clay, with a 6.5 cm leachate column above for a source.

 

Case 10

 

In this example the Variable Properties option is used to examine time-varying advective-dispersive transport from a landfill. A landfill with a finite mass and a leachate collection system with an inward Darcy Velocity (i.e., a hydraulic trap) is considered. The leachate collection system is assumed to begin to fail after 19 years. After failure of the leachate collection system the leachate mound builds over a 10 year period, causing a reversal in the hydraulic gradient and a loss of the hydraulic trap.

 

Case 11

 

This example demonstrates the use of a time-varying source concentration and an initial concentration profile. A landfill cell is initially filled with fresh water, and no waste is deposited for 7 years. The landfill is situated in a clay with a pore water chloride concentration, during the initial 7 years the chloride from the clay diffuses into the cell water. Between 7 and 10 years the cell is filled with waste and the chloride concentration increases linearly to 2100 mg/L. The source concentration then remains constant between 10 and 13 years. Between 13 and 15 years the source concentration decreases linearly to 1180 mg/L. The source concentration then remains constant between 15 and 19 years.

 

Case 12

 

In this example the results of the program are compared with an analytical solution developed by Tang et al. (1981). The analysis is for a single fracture system. It is shown that the program gives exactly the same results as the analytical solution.

 

Case 13

 

The results of the program are compared to the results obtained by an analytical solution given by TDAST. The TDAST program was developed by Javandel et al. (1984), and is for a 2-dimensional plane dispersion problems in an infinitely deep porous media. Concentrations obtained by both methods are in close agreement for a dispersion coefficient of 0.01 m2/a. However, at higher dispersion coefficients, for example 5 or 10 m2/a, the methods are not in agreement. This is because for the geometry and time frame

considered in this problem, a 2-dimensional solution is required and POLLUTEv7 considers only 1-dimensional migration in the layer below the source.

 

Case 14

 

In this example a landfill with primary and secondary leachate collection systems is modelled using the Passive Sink option. The secondary leachate collection system is simulated using a passive sink to model outflow from the collection system. The landfill contains a finite mass of a conservative species, and is underlain by an aquifer with fixed outflow.

 

Case 15

 

In this example the model of Case 14 is extended to incorporate failure of the primary leachate collection system after 20 years. This failure is modelled using the Variable Properties special feature. The use of the Variable Properties and Passive Sink features together is illustrated in this example.

 

Case 16

 

This example illustrates the use of the Monte Carlo simulation feature, in conjunction with the Variable Properties and Passive Sink features. The landfill model used in Case 15 is modified to simulate uncertainty in the time of failure of the primary leachate collection system. In this example the failure time is given a triangular distribution, with a minimum of 15 years, a mode of 25 years, and a maximum of 50 years.

 

Case 17

 

This example demonstrates how to create a landfill with a composite primary liner, primary and secondary leachate collection systems, and a compacted clay secondary liner.

 

Case 18

 

In this example a phase change in the secondary leachate collection system is modelled using the Phase Change special feature. The phase change occurs in the secondary leachate collection system at the interface between the unsaturated and saturated zones, assumed to be .2 and .1 meters thick respectively. The landfill contains a constant concentration of DCM, which experiences biological decay in the landfill, primary and secondary liners, and the aquifer.

 

Case 19

 

In this example a multiphase diffusion test performed by Buss et al. (1995) is modelled. This test involved the migration of toluene from a ‘constant’ source through a 0.1 cm thick HDPE geomembrane, a 18.2 cm thick airspace and into a 12.3 cm water reservoir (assumed to be well mixed).

 

Case 20

 

This example uses the same date as Case 16 for Monte Carlo simulation, except a Sensitivity Analysis is performed. In this example the failure time has a minimum of 15 years and a maximum of 50 years.