Chlorinated solvent contaminated soils and groundwater: field application of the solvent extraction residual biotreatment technology - Bioremediation of Recalcitrant Compounds - page 76

Table 5.1a Natural Attenuation Parameters and Criteria Points

Criteria
Points
Awarded

Concentration
Criteria Analyte Interpretation

Oxygen <0.5 mg/l Tolerated; suppresses reductive

dechlorination at higher
concentrations

3

Oxygen >1 mg/l Vinyl chloride may be oxidized

aerobically, but reductive
dechlorination will not occur

-3

Nitrate <1 mg/l May compete with reductive

pathway at higher concentration

2

Iron (II) >1 mg/l Reductive pathway possible 3

Sulfate <20 mg/l May compete with reductive

pathway at higher concentration

2

Sulfide >1 mg/l Reductive pathway possible 3

Methane >0.1 mg/l Ultimate reductive daughter

product

2

Methane >1 mg/l Vinyl chloride accumulates 3

Methane <1 mg/l Vinyl chloride oxidizes —

Oxidation-reduction
potential

<50 Reductive pathway possible <50 = 1;

<-100 = 2

pH 5< pH <9 Tolerated range for reductive

pathway

—

Total organic carbon >20 mg/l Carbon and energy source; drives

dechlorination; can be natural or
anthropogenic

2

Temperature >20°C At T > 20˚C, biochemical process

is accelerated

1

Alkalinity >2°

background

Results from interaction of carbon
dioxide with aquifer minerals

1

Chloride >2°

background

Daughter product of organic
chlorine; compare chloride in
plume to background conditions

—

Perchloroethene Material released 2

Trichloroethene Material released or daughter

product of perchloroethene

2

Dichloroethene Material released or daughter

product of perchloroethene; if
amount of cis-1,2-dichloroethene
is greater than 80% of total
dichloroethene, it is likely a
daughter product of
trichloroethene

2