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

5.3.4 Wastewater Analysis. Retrieved wastewater samples were tested by American Analytical
Laboratories, Inc., on April 14, 2010, in accordance with EPA Test Methods. EPA Method 150.1 was
used to determine the pH of the samples. EPA Method 8015 was used to determine the DRO and GRO
concentrations to test for the presence of petroleum hydrocarbons. The results are listed in Table 5-12.
The pH value measured (7.54) is indicative of typical residential sewage. The wastewater analysis
suggests that the wastewater stream has characteristics typical to residential areas, and no abnormal pH
value or hydrocarbon concentrations were measured.
Table 5-12. Results of Wastewater Analysis for Columbus 36-in. Liner
Sample ID pH
86
DRO
(mg/L)
GRO
(mg/L)
Pearl 36 7.54 1.99 34.3
5.3.5 Annular Gap. A feeler gauge was used to measure the annular space around the perimeter
where the sample was removed. The liner appeared to be very tight along the sides and bottom of the
sample and a spacing greater than 0.127 mm was measured at only three locations (see Figure 5-31) – all
along the top side of the sample removal area (see note on crown annulus gap in Section 5.3.3). The end
measurements shown in Figure 5-31 were taken at approximately 4 in. from each end of the cutout and
the middle measurement was taken at its center. Since the liner sample was removed from the host pipe,
no laboratory annular space measurements were possible.
Figure 5-31. Annular Space Measurements Around the Sample Removal Area
(Columbus 36-in. Liner)
5.3.6 Liner Thickness
1.64mm 0.86mm
0.87mm
Gap determined to be < .127 on sides and bottom. Feeler
Gauge minimum is .127
5.3.6.1 Ultrasound Testing. An ultrasonic meter (Olympus 37DL Plus) with a 2.25 MHz contact
transducer was utilized in the field in an attempt to measure the thickness of the CIPP liner (Figure 5-32).
However, the ultrasound testing for thickness did not produce any readings (apparently due to the
thickness of this liner). This issue is discussed further in Section 6.
5.3.6.2 Field Measurements. Caliper measurements of the exhumed liner thickness were recorded
around the edges of the extracted sample in the field as shown in Figure 5-33. The liner thickness
measurements taken in the field are shown in Figure 5-34. The average thickness for the sample was
calculated to be 14.2 mm and standard deviation was 1.5 mm. The original design thickness was not
known, but it was assumed to be 15 mm (i.e., the same as the liner used for the adjacent line).