Page 195 - Materials Chemistry, Second Edition

178 Practical Design Calculations for Groundwater and Soil Remediation

Use Table 2.4 to convert the Henry’s constant to a dimensionless
value:

H = H/RT = (6.7)/[(0.082)(273 + 20)] = 0.28 (dimensionless)
*
Use Equation (2.28) to find K :
oc
K = 0.63K = 0.63 (10 2.73 ) = (0.63)(537) = 338
ow
oc
Use Equation (2.26) to find K :
p
K = f K = (0.01) (338) = 3.4 L/kg
oc
oc
p
Use the saturated gasoline vapor concentration of weathered
gasoline, 226 mg/L (from Example 5.1) and Equation (5.2) to
estimate X :
sat

  (0.35)(40%) + (1.6)(3.4) + (0.35)(1 40%)−  

 
X sat =   0.28 0.28  × (226)
 1.8  

= 2,528 mg/kg

(c) Determine the amount of TPH to be removed before the disap-
pearance of the free-product phase by using Equation (5.12):

M = (V)(ρ ) = (6,500 ft )[(1.8 × 62.4 lb/ft )]
3
3
s
t
s
= 730,100 lb = 332,000 kg
M removal = (X initial – X )(M )
sat
s
= (6,000 − 2,528 mg/kg)(332,000 kg)
= 1.153 × 10 mg = 1,153 kg
9
(d) Estimate the extracted vapor concentration using Equation (5.1):
As determined in Example 5.1, the saturated gasoline vapor
concentrations are 1,343 mg/L and 226 mg/L for the fresh
and the weathered gasoline, respectively. Since the observed
VOC concentrations of the extracted vapor often decrease
exponentially over time, the geometric average of these two
values is used as the average concentration for this interval:

G = (1,343)(226) = 551 mg/L