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

4.2.4 Locations of Soil Samples. The trench was divided into six regions (Figure 4-3) for soil
sampling. Soil samples collected from each region were placed in airtight bags to avoid foreign
contamination and/or loss of moisture. The samples were numbered as shown in Table 4-1.
Figure 4-3. Location of
Soil Sample Collection
Place (Denver 8-in. Site)
Table 4-1. Designation of Collected Soil Samples for
Denver 8-in. Site
Soil Sample Location Sample ID
Sub-grade 1
2 ft below sub-grade 2
4 ft below sub-grade 3
Just above crown 4
Bedding along the spring line 5
Bedding under the invert 6
4.2.5 Analysis of Soil Samples. Standard test methods ASTM C136 and ASTM C128 were
followed to classify the soil and determine its particle size distribution. In addition to those tests, the pH
of the soil samples was measured using a pH meter.
4.2.5.1 Particle Size Distribution. ASTM C136, a standard testing method used for performing sieve
analysis on geological material, was followed for the particle size distribution analysis. Based on visual
inspection, soil samples were categorized as fine aggregates. For this analysis, 500 g of soil material was
taken from each of the six soil samples and placed on a No. 4 sieve. For all samples, more than 90% of
the particles passed through a No. 4 (4.76 mm) sieve, suggesting that the analysis procedure for fine
aggregates should be followed. The resulting gradation curves are shown in Figure 4-4.
Based on grain size distribution, both the backfill and bedding soils can be considered to be sandy soils.
The steep slopes of the resulting gradation curves for the samples taken from the spring line and invert
elevations suggest that the bedding material consists of uniform (poorly-graded) soil. For the other
locations, the gradation of soil was determined to be a fair-graded material. Review of bore logs collected
as part of utility construction projects performed in nearby areas revealed that the native soil in the top 5
ft consist of sandy-silt underlying by gravelly sand (between 5 ft and 12 ft).
4.2.5.2 Soil Specific Gravity and Absorption. ASTM C128 standard method was used to calculate
the density, relative density, and absorption of fine aggregates. Soil material weighing 500 g was taken
from each of the six samples for the needed tests. The results are listed in Table 4-2.
4.2.5.3 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 4-3.
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