Retrospective Evaluation of Cured-in-Place Pipe - (NEPIS)(EPA ...

5.2.5.3 Soil Moisture Content. ASTM D2216 is a test method used to determine the moisture
content in soils and rocks by mass. Samples weighing 1,000 g from each of the six locations were placed
in an oven for a period of 24 hr. After 24 hr, the soil samples were weighed and returned to the oven for
an additional 24-hr period. The process was repeated until the difference between two subsequent
measured weights was less than 1 g. At this point, the soil was assumed to be moisture free. Moisture
content values for the six soil samples are listed in Table 5-3.
Table 5-3. Soil Moisture Content Results (Columbus 8-in. Site)
Sample ID Moisture Content (%)
1 5.65
2 16.47
3 19.77
4 17.34
5 22.54
6 23.83
5.2.6 Measurement of Acidity, Alkalinity, and pH. The pH of the soil embedment and the solid
sediments collected from the pipe invert were measured using a Thermo Orion and a sympHony SP70P
pH meter (see Figure 5-6). The soil samples were placed in a pan (which was rinsed using distilled water)
and distilled water was added to the samples. The soil sample was then stirred, and the pH probe was
inserted into the soil-water mixture. The process was repeated for the sediments collected from the
bottom of the liner on the inside of the pipe. The pH values of the bedding soil, backfill soil, and the
sediments are listed in Table 5-4.
Figure 5-6. Measurement of pH (Columbus 8-in. Soil Samples)
The pH of soil samples collected from around the pipe (bedding material) and the backfill soil were found
to be somewhat alkaline ranging from 7.3 to 8.9. The sediments inside the pipe were also found to be
slightly alkaline (with an average pH of 7.6) as expected from a residential wastewater stream. These
measurements do not provide any indication of a severe service environment for the liner.
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