Oil Contamination

[Name of the Author]

Oil Contamination

In Figure 1, the study area is intentionally enormous compared to the actual site's area, and the real location is somewhere inside the circle. Moreover, conventional geographical directions are used only in the sections covering descriptions of geomorphology and geology. All data measurements are on core samples from the boreholes, the most frequent nearest neighbor distance between them is around 40 m. However, the number of samples per borehole is not constant, as the length of the wells is not constant. In fact, this number varies between a minimum of two and a maximum of seven samples, and on average there are five cores per borehole. There is no obvious pattern in the locations of the boreholes that have the most samples and they are fairly uniformly spread over the study area; moreover, the reason for the differing numbers of sample in boreholes is not known. The length of samples in each borehole varies from a minimum of 0.1m to a maximum of 1m, as shown by the statistics listed in Figure 2(a) together with the histogram of core lengths (Burgess, 1980).

The lengths of the data gaps caused by these discontinuities are summarized in the histogram and statistics shown in Figure 2(b) which indicate that the lengths of most gaps (i.e. missing data) are either between 0.5 m and 1.5m, or between 2.5 m and 3.0 m. Figure 2(b) does not give any indication of the locations of the gaps. Most of the 1.5m gaps are located at a depth of 4.5 m (22.9% of the total number of gaps), and most of the 1.0m gaps are located at a depth of 2.5 m (20.8%). These observations informed the choice of parameter values in the recomposition procedure (Dowd, 1997).

As the raw data values are measured on unequal sample lengths, the grades must be composited over equal lengths to ensure that all data have the same support.

In the main menu in the Plot View window select Map( Post Map( New Post Map… and then select main file from the desktop.

Screen Shot 1

Click on the Labels Tab and insure that the Column C: Elevation is set as the “Worksheet Column for Labels” and that 0.30in is set for the “label Lines Length.”

The following type figure will appear on the main screen of the Surfer Software Program.

Screen Shot 2

Source: (Burgess, 1980)

Source: (Dowd, 1997)

From the histogram in Figure 2(a) a composite length of 0.5 m was chosen, since it appears to be the most representative length, it is an appropriate scale of measurements and minimizes the number of actual sample lengths that are subdivided in the compositing procedure. As additional check on the compositing procedures parameters, the lengths of the raw samples were analyzed in terms of the number with grades exceeding the terrain acceptable concentration limits (TACL) fixed by environmental Italian law. These values may be spatial outliers that could mask the underlying variogram of each variable. As all such lengths are very close ...