Natural Attenuation - Dealing with Contaminated Sites: From Theory Towards Practical Application - page 988

Table 22.1 Summary of investigation methods to prove the effectiveness of NA at petroleum hydrocarbon contaminated sites

Aim Method Comments

Source zone
characterization

Source localization Investigation of soil and groundwater samples Standard method, invasive and destructive

method, direct measurements

Direct-push (DP) investigations using in-situ
contaminant detectors (LIF / ROST or
MIP-PID, -FID, -DELCD)

Invasive, but non-destructive method, indirect
measurements, influenced by soil and
contaminant characteristics

In-situ radon analyses in the soil gas to detect
radon depletions due to NAPL presence

Indirect measurement of NAPL presence,
depend on soil characteristics

NAPL mobility Pumping tests w/o tracer tests in the NAPL

phase

Only in highly permeable aquifers with
significant NAPL thicknesses suitable

Source mass Calculation of mass from 3-phase profiles

using apparent NAPL phase thicknesses
from groundwater monitoring wells and
pedo-physical parameters

Indirect calculation, based on measured
parameters

NAPL composition NAPL phase analyses and derivation of

contaminant specific saturation
concentrations

Standard method

Column experiments to measure saturation
concentrations

For confirmation of NAPL phase analyses

Source emission Tank experiments to measure source emission Highly laborious method with restricted

transferability to the field

Analytical and/or numerical calculation of
source emission from NAPL

Indirect calculation based on various measured
parameters; numerical calculations highly
complex

Plume characterization Spatial and temporal

plume delineation

Conventional groundwater sampling Standard method, good reproducibility

Multilevel groundwater sampling using e.g.,
DP low cost and small diameter monitoring
wells

Often special pumping equipment necessary