Contaminant Mobility
This is the first in a series of articles on the development of soil alternative remediation standards (ARS) protective of groundwater quality under the New Jersey Department of Environmental Protection (NJDEP) guidance. Future articles will cover specific methods such as the soil water partitioning equation (SPE), synthetic precipitate leaching procedure (SPLP), and modeling options.
Development of Alternative Remediation Standard Concentrations
Under the NJDEP guidance contaminants must be divided based on mobility. This is because selection of specific methods used to develop ARS is dependent upon contaminant mobility. Thus the first step of the ARS process is to determine if you are dealing with mobile or immobile contaminants. In reality contaminant mobility can be very complex and is dependent on many factors including chemical properties, permeability, organic carbon content, and pH. Mobility is also greatly influenced by climatic conditions and even depth to groundwater.
Determination of Contaminant Mobility
So how do you determine which contaminants are considered mobile and immobile. The NJDEP 2007 basis and background document defines contaminants with Koc values of 20,000 L/kg and higher as immobile. This designation is based on a paper by Roy and Griffin (1985) of the Illinois State Geological Survey. They evaluated the aqueous mobility of various organic solvents and classified them as having various degrees of mobility, ranging from very highly mobile to immobile.
An alternative method using the SESOIL vadose zone model is presented in the NJDEP 2004 draft version of the “Basis and Background Document Impact to Ground Water Pathway”. This approach was used to evaluate contaminant mobility under typical New Jersey conditions. Chemical parameters for a generic contaminant were established. In every instance chemical properties were selected that enhanced contaminant mobility. Koc values were then varied to observe the influence on contaminant migration (Table 1). Modeling was performed using a sandy loam soil located in Trenton, New Jersey. Soil properties were established based on information contained in the SEVIEW Users Guide. Climatic parameters for Trenton were obtained from the SEVIEW climatic database.
Table 1
Contaminant Migration Based on
SESOIL Modeling
Koc
(L/kg)
|
Contaminant Migration
over 100 years
(inches)
|
Travel Time to
Groundwater
(years)
|
|
100,000
|
3.6
|
3,333
|
|
80,000
|
5.4
|
2,222
|
|
50,000
|
10.9
|
1,100
|
|
30,000
|
20.5
|
585
|
Predicted migration rates ranged from 3.6 to 20.5 inches over 100 years. Using a depth of 10 feet to the water table this corresponds to total travel time to groundwater of between 585 and 3,333 years. Based on these results the NJDEP determined that chemicals with Koc values of 50,000 L/kg and higher would migrate less than one foot over 100 years. They also point out that a Koc of 50,000 L/kg is equivalent to Kd of 100 L/kg for metals.
Contaminant Classification
I’ve compiled a list of Koc and Kd values used by the NJDEP. There are a total of 96 mobile organic contaminants (Table 2) and 31 immobile organic contaminants (Table 3). It makes very little difference if the 20,000 or 50,000 L/kg value is used as there are only four chemicals with Koc values that fall in this range (Table 4).
Table 2
Mobile Organic Contaminants
|
Chemical
|
Koc
|
|
1,1,1-Trichloroethane
|
110
|
|
1,1,2,2-Tetrachloroethane
|
93.3
|
|
1,1,2-Trichloro-1,2,2-trifluoroethane
|
410
|
|
1,1,2-Trichloroethane
|
50.1
|
|
1,1'-Biphenyl
|
8,556
|
|
1,1-Dichloroethane
|
31.6
|
|
1,1-Dichloroethene (1,1-Dichloroethylene)
|
58.9
|
|
1,2,4-Trichlorobenzene
|
1,780
|
|
1,2-Dibromo-3-chloropropane
|
79.0
|
|
1,2-Dibromoethane
|
46.0
|
|
1,2-Dichlorobenzene
(o-Dichlorobenzene)
|
617
|
|
1,2-Dichloroethane
|
17.4
|
|
1,2-Dichloroethene (cis)
(c-1,2-Dichloroethylene)
|
35.5
|
|
1,2-Dichloroethene (trans)
(t-1,2-Dichloroethylene)
|
52.5
|
|
1,2-Dichloropropane
|
43.7
|
|
1,2-Diphenylhydrazine
|
710
|
|
1,3-Dichlorobenzene
(m-Dichlorobenzene)
|
708
|
|
1,3-Dichloropropene (cis
and trans) (summed)
|
45.7
|
|
1,4-Dichlorobenzene
(p-Dichlorobenzene)
|
617
|
|
2,4,5-Trichlorophenol
|
2,340
|
|
2,4,6-Trichlorophenol
|
999
|
|
2,4-Dichlorophenol
|
159
|
|
2,4-Dimethylphenol
|
209
|
|
2,4-Dinitrophenol
|
0.018
|
|
2,4-Dinitrotoluene
|
95.5
|
|
2,6-Dinitrotoluene
|
69.2
|
|
2-Butanone (Methyl ethyl
ketone) (MEK)
|
1.0
|
|
2-Chlorophenol
(o-Chlorophenol)
|
398
|
|
2-Hexanone
|
24.0
|
|
2-Methylnaphthalene
|
6,820
|
|
2-Methylphenol (o-cresol)
|
91.2
|
|
2-Nitroaniline
|
74.0
|
|
3,3'-Dichlorobenzidine
|
724
|
|
4,6-Dinitro-2-methylphenol
|
116
|
|
4-Chloro-3-methyl phenol
(p-Chloro-m-cresol)
|
1,116
|
|
4-Chloroaniline
(p-Chloroaniline)
|
66.1
|
|
4-Methyl-2-pentanone (MIBK)
|
15.0
|
|
4-Methylphenol (p-cresol)
|
74.0
|
|
4-Nitrophenol
|
74.0
|
|
Acenaphthene
|
7,080
|
|
Acenaphthylene
|
2,759
|
|
Acetone (2-propanone)
|
0.6
|
|
Acetophenone
|
37.0
|
|
Acrolein
|
1.0
|
|
Acrylonitrile
|
2.0
|
|
alpha-HCH (alpha-BHC)
|
1,230
|
|
Atrazine
|
360
|
|
Benzaldehyde
|
29.0
|
|
Benzene
|
58.9
|
|
Benzidine
|
47.0
|
|
beta-HCH (beta-BHC)
|
1,260
|
|
Bis(2-chloroethyl)ether
|
15.5
|
|
Bis(2-chloroisopropyl)ether
(2,2'-oxybis(1-chloropropane))
|
360
|
|
Bromodichloromethane
(Dichlorobromomethane)
|
55.0
|
|
Bromoform
|
87.1
|
|
Bromomethane (Methyl
bromide)
|
10.5
|
|
Caprolactam
|
6.0
|
|
Carbazole
|
3,390
|
|
Carbon disulfide
|
45.7
|
|
Carbon tetrachloride
|
174
|
|
Chlorobenzene
|
219
|
|
Chloroethane
|
15.0
|
|
Chloroform
|
39.8
|
|
Chloromethane (Methyl
chloride)
|
6.0
|
|
Dibenzofuran
|
13,455
|
|
Dibromochloromethane
(Chlorodibromomethane)
|
63.1
|
|
Dichlorodifluoromethane
|
66.0
|
|
Diethylphthalate
|
288
|
|
Dimethylphthalate
|
37.0
|
|
Endosulfan I and
Endosulfan II (alpha and beta) (summed)
|
2,140
|
|
Endosulfan sulfate
|
1,020
|
|
Endrin
|
12,300
|
|
Ethylbenzene
|
363
|
|
Fluorene
|
13,800
|
|
Hexachloroethane
|
1,780
|
|
Isophorone
|
46.8
|
|
Lindane (gamma-HCH) (gamma-BHC)
|
1,070
|
|
Methyl acetate
|
2.0
|
|
Methylcyclohexane
|
865
|
|
Methylene chloride
(Dichloromethane)
|
11.7
|
|
MTBE (tert-butyl methyl
ether)
|
8.0
|
|
Naphthalene
|
2,000
|
|
Nitrobenzene
|
64.6
|
|
N-Nitrosodimethylamine
|
0.3
|
|
N-Nitrosodi-n-propylamine
|
24.0
|
|
N-Nitrosodiphenylamine
|
1,290
|
|
Pentachlorophenol
|
5,100
|
|
Phenol
|
28.8
|
|
Styrene
|
776
|
|
Tertiary butyl alcohol
(TBA)
|
2.0
|
|
Tetrachloroethene (PCE)
(Tetrachloroethylene)
|
155
|
|
Toluene
|
182
|
|
Trichloroethene (TCE)
(Trichloroethylene)
|
166
|
|
Trichlorofluoromethane
|
114
|
|
Vinyl chloride
|
18.6
|
|
Xylenes (total)
|
386
|
Table 3
Immobile Organic Contaminants
|
Chemical
|
Koc
|
|
4,4'-DDD (p,p'-TDE)
|
1,000,000
|
|
4,4'-DDE (p,p'-DDX)
|
4,470,000
|
|
4,4'-DDT
|
2,630,000
|
|
Aldrin
|
2,450,000
|
|
Anthracene
|
29,500
|
|
Benzo(a)anthracene
(1,2-Benzanthracene)
|
398,000
|
|
Benzo(a)pyrene
|
1,020,000
|
|
Benzo(b)fluoranthene
(3,4-Benzofluoranthene)
|
1,230,000
|
|
Benzo(ghi)perylene
|
3,858,158
|
|
Benzo(k)fluoranthene
|
1,230,000
|
|
Bis(2-ethylhexyl)phthalate
|
15,100,000
|
|
Butylbenzyl phthalate
|
57,500
|
|
Chlordane (alpha and
gamma)
|
120,000
|
|
Chrysene
|
398,000
|
|
Dibenz(a,h)anthracene
|
3,800,000
|
|
Dieldrin
|
21,400
|
|
Di-n-butyl phthalate
|
33,900
|
|
Di-n-octyl phthalate
|
83,200,000
|
|
Dioxin (TCDD)
(2,3,7,8-Tetrachlorodibenzo-p-dioxin)
|
2,453,466
|
|
Fluoranthene
|
107,000
|
|
Heptachlor
|
1,410,000
|
|
Heptachlor epoxide
|
83,200
|
|
Hexachloro-1,3-butadiene
|
53,700
|
|
Hexachlorobenzene
|
55,000
|
|
Hexachlorocyclopentadiene
|
200,000
|
|
Indeno(1,2,3-cd)pyrene
|
3,470,000
|
|
Methoxychlor
|
97,700
|
|
PCBs (Polychlorinated
biphenyls)
|
309,000
|
|
Phenanthrene
|
26,533
|
|
Pyrene
|
105,000
|
|
Toxaphene
|
257,000
|
Table 4
Chemicals with
Varying Mobility Classification
|
Chemical
|
Koc (L/kg)
|
|
Dieldrin
|
21400
|
|
Phenanthrene
|
26533
|
|
Anthracene
|
29500
|
|
Di-n-butyl
phthalate
|
33900
|
The NJDEP provides Kd values for 19 metals. Using the 2004 classification 15 chemicals are considered mobile (Table 5), while the remaining four are considered immobile (Table 6).
Table 5
Mobile Metals
Chemical
|
Kd (L/kg)
|
|
Antimony (total)
|
45
|
|
Arsenic (total)
|
26
|
|
Barium (total)
|
17
|
|
Beryllium
|
35
|
|
Cadmium
|
23
|
|
Chromium (total)
|
28
|
|
Cobalt (total)
|
45
|
|
Cyanide
|
9.9
|
|
Manganese (total)
|
65
|
|
Mercury (total)
|
0.20
|
|
Nickel (total)
|
24
|
|
Selenium (total)
|
14
|
|
Silver (total)
|
0.25
|
|
Thallium (total)
|
48
|
|
Zinc (total)
|
23
|
Table 6
Immobile Metals
Chemical
|
Kd (L/kg)
|
|
Aluminum (total)
|
1,500
|
|
Copper (total)
|
430
|
|
Lead (total)
|
900
|
|
Vanadium (total)
|
1,000
|
Summary
In New Jersey contaminants must be classified based on environmental mobility in order to select appropriate methods to develop ARS.
In the next newsletter we will look at the use of the SPE and dilution-attenuation factor (DAF) equations to develop ARS cleanup concentrations for soil.
|
|
|
