Environmental Engineering Reference
In-Depth Information
control borehole levels and were concentrated in boreholes around the graves, with
highest levels in younger graves (Fig. 7.17). It has been suggested that P is leached to
orthophosphates which are locked into insoluble components at pH < 5 and pH > 7 and
are then transformed into soluble components by microorganisms in the soil (Dent et al.
2004). This could explain the high PO
4
levels in fairly recent graves, indicating the
source of the phosphate being from the decay of corpses. Sulphate was detected in high
levels boreholes GBH1, GBH4 and GBH7, in the fairly recent graves. The high levels of
nitrates and sulphate around the graves suggest that they may be formed after dissolution
of the gases (e.g. NH
3
, CH
4
, H
2
S), which are released during decomposition in anaerobic
conditions (Dent et al
.
2004).
Some parameters are higher than the South Africa domestic water guideline (DWAF
1996) and the World Health Organization drinking water guidelines (WHO 1993) as
shown in Table 7.3; therefore the water around the cemetery is unsafe for domestic use.
Comparison to the control borehole suggests that the cemetery is a source of groundwater
pollution, with potassium, sodium, nitrates, sulphate, phosphate and coliform bacteria all
showing elevated levels in the study boreholes.
The development of a tree barrier (Fig. 7.18), and the grouting of the downflow side of
the site-as discussed for Golden Quarry above-are also recommended for Granville. In
addition, the advantages mentioned in the previous section are valid for this section too.
Figure 7.15. Spatial variation of fecal
coliform in groundwater, Granville
Cemetery 'B' (Values are in cfu. ×
10
4
).
