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

(average of 6,900 psi) and flexural modulus of elasticity (average of 490,000 psi) were both well above
the specified values at the time of installation (4,500 psi and 250,000 psi, respectively). Overall
comparisons can be found in Section 6.
Table 4-13. Historic Sampling Results for the CIPP Liner Tested in 1995 (Denver 48-in. Liner)
Sample Tensile
Break
Strength
(psi)
Tensile
Elongation
at Break
(%)
48
Flexural
Break
Strength
(psi)
Flexural
Modulus of
Elasticity
(psi)
1 2,500 1.8 7,400 520,000
2 2,400 1.3 7,000 530,000
3 2,100 1.3 6,500 470,000
4 - - 6,400 430,000
5 - - 7,300 520,000
Mean 2,300 1.5 6,900 490,000
Std Dev 170 0.2 400 40,000
4.3.3 Sample Retrieval in 2010. Two samples, each approximately 2 ft × 2 ft, were exhumed
from the installed liner on May 20, 2010, by Wildcat Civil Services of Kiowa, CO with Jack Row, the
General Superintendent, on site. (The liner age at this time was 23 years.) Both samples were taken from
the crown of the pipe at a distance about 4 ft from manhole B-3 (one upstream and the other downstream
of the manhole). The samples were sent to TTC for testing. Figure 4-27 shows images of the recovered
specimens.
Figure 4-27. Images of the Recovered Samples from the Denver 48-in. Liner
4.3.4 Annular Gap. Annular space measurements were not collected for this sample due to the
circumstances of sample retrieval.
4.3.5 Liner Thickness
4.3.5.1 Downstream Sample. For determining the liner thickness of the downstream sample, 10
readings were taken at six different locations around the sample (a total of 60 readings) using a
micrometer with a resolution of ±0.0001 in. The average calculated values and their standard deviations
are shown in Figure 4-28. The weighted average for the sample thickness measurements was calculated
to be 13.9 mm and the weighted error ±0.3 mm.