Department of Civil and Environmental Engineering

The University of Connecticut - Storrs

Assignment #2 for

CE-279 and CE-405

Environmental Systems Analysis

Spring 2000


Problem 1. Chemical Movement Through a Recompacted Clay Liner

You are in the process of designing an impoundment out of recompacted clay for the short term storage of a liquid waste containing a phenol. Assuming that the phenol concentration in the impoundment remains relatively constant and it is approximately 1.5 mg/L, the background ground water phenol concentration is 0.01 mg/L, and the diffusion coefficient of phenol in the clay is 5e-5 cm2/s, calculate how long will it take for the phenol to travel through 50 cm of clay and contaminate the ground water. Plot the phenol concentration as a function of depth of the clay layer. How deep should the clay layer be if one wanted to store the liquid for 5 years?

Problem 2. Estimation of the Diffusion Coefficient in Wetland Sediments

The following data were obtained from a pore water sediment sampler (similar to the one described in the class) and represent the chromium distribution in the pore water of the wetland sediment. The chemical spill occurred 180 days before the measurements were made. The concentration of chromium in the spill was 100 mg/L. The background chromium concentration is 0.001 mg/L. Calculate the diffusion coefficient.

z, cm Chromium Concentration, mg/L

1 50

2 17

3 5.6

4 3.8

5 1.4

6 0.6

7 0.2

Due date: February 9, 2000.

Instructor: Dr. Nikolaos P. Nikolaidis

Office: FLC Rm 318

e-mail: nikos@eng2.uconn.edu

Homepage: http://www.eng2.uconn.edu/cee/bio/Nikolaidis.html

Office Hours: MW 3:00 - 4:30 PM


e-mail: nikos@eng2.uconn.edu