CE En 540 - Homework #10

BIOSCREEN

Go to the BIOSCREEN and BIOCHLOR download page and download a copy of the BIOSCREEN model to your local drive.  Open the BIOSCREEN spreadsheet in Excel.

The objective of this assignment is to use BIOSCREEN to model BTEX degradation at a site.  We will use the simple first order decay reaction model.  Assume the following conditions:

1. Hydrogeology

Seepage Velocity = 150 ft/yr

2. Dispersion

Estimated Plume Length = 350 ft.

3. Adsorption

Retardation Factor = 1.5

4. Biodegradation

You will find a value for the 1st order decay coeff. that calibrates the model to the field data.

Ignore the instantaneous reaction terms.

5. General

Modeled Area Length = 400 ft

Modeled Area Width = 200 ft

Simulation Time = 3 years

6. Source Data

Source Thickness in Saturated Zone = 6 ft.

Source Zones:

Width	Conc. (mg/L)
36	0.1
20	5.0
14	20.0
20	5.0
36	0.1

Source mass = 150 kg

7. Field Data (at t=3 yrs)

Conc.	18.6	7.5	2.4	0.53
Distance From Source	0	40	120	240

Problem:

Enter the values shown above.  Estimate a value of the decay coeff. and run a centerline analysis to see if the computed values match the observed values.  Change the decay coeff. and iterate until you get a good match.

Optimal decay coeff. = __________________

Change the simulation time to 25 yrs.  Enter the predicted concentrations at the monitoring well locations:

Submittal Instructions:

Copy this assignment to a Word document and fill in the data requested at the bottom.  When finished, create a zip archive containing both the word document and your BIOSCREEN Excel file.  Click here to upload the zip archive electronically to the TA for grading.