Page 49 - Materials Chemistry, Second Edition

32 Practical Design Calculations for Groundwater and Soil Remediation

Step 2: Measure the apparent thickness of the free product inside the
well.
Step 3: Calculate the actual thickness of free product in the formation
by inserting values of these parameters into Equation (2.12).

Information needed for this calculation

• Specific gravity (or density) of the free product, SG
• Measured thickness of the free product in the well, t
• Capillary rise, h c

To determine the mass and volume of the free-floating product, the follow-
ing procedure can be used:

Step 1: Determine the areal extent of the free-floating product.
Step 2: Estimate the true thickness of the free-floating product.
Step 3: Calculate the volume of the free-floating product by multiply-
ing the area with the true thickness and the effective porosity of
the formation.
Step 4: Calculate the mass of the free-floating product by multiplying
the volume with its density.

Information needed for this calculation

• Areal extent of the free-floating product
• True thickness of the free-floating product
• Effective porosity of the formation
• Density (or specific gravity) of the free-floating product

Example 2.17: Determine the True Thickness of
the Free-Floating Product
A recent survey of a groundwater monitoring well showed a 75-in.-thick
layer of gasoline floating on top of the water. The density of gasoline is 0.8
g/cm , and the thickness of the capillary fringe above the water table is 1 ft.
3
Estimate the actual thickness of the free-floating product in the formation.

Solution:
Using Equation (2.12), we obtain:
Actual free-product thickness in the formation (t )
g
= (75)(1 − 0.8) − 12 = 3 in.