Environmental Engineering Reference
In-Depth Information
Figure 7.15
Photograph of sampling grid and soil corer used to collect samples from
the troughs.
probes were reinserted. The random sampling process developed during the
pilot study was instrumental in decreasing the error inherent in soil contam-
inant analysis due to contaminant heterogeneity.
Soil samples were obtained from the troughs in a manner similar to that
of the LTUs. Replicate samples were obtained from each of the five sampling
zones as a composite of five randomly selected subsamples. The subsamples
were collected as cores, combined in a 950-cc amber glass sample jar, and
manually homogenized. The grid and soil corer used to obtain samples are
shown in Figure 7.15. Samples were collected from the troughs weekly
following gas analysis. Chemical and microbial analysis was performed as
scheduled, and the remainder of each sample was archived at 4˚C. The
troughs were tilled after each sampling event by a rototiller with a maximum
depth of 12 in. When water was added to the troughs, it was added before
tilling.
7.3.10.2 Physical analysis
Atterberg limit analysis and particle size distribution (PSD) were used to
evaluate the physical structure of both the untreated and treated soils. The
Atterberg limit test was performed by the Geotechnical Laboratory at the
WES-USAERDC (
Corps of Engineers Laboratory Testing Manual
,
EM-1110-2-1906, “Appendix III: Liquid and Plastic Limits”). Particle size
distribution was measured on a Coulter LS100Q particle counter according
to instrument protocol. Soil moisture was analyzed on a Denver Instrument
IR-100 moisture analyzer and validated by oven drying at 105˚C for 24 h.
7.3.10.3 Chemical analysis
Contaminant concentration, metals, nitrogen, phosphate, and total organic
carbon analyses were performed by the Environmental Chemistry Branch
of the Waterways Experiment Station on both treated and untreated soil.
PAH and PCP concentrations were determined using SW846 EPA Method
