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

Göttingen Stadtentwässerung: Göttingen has taken samples of CIPP lining after 5 and 10 years in
service, and some after 12 years. Pieces roughly the size of a sheet of letter paper were removed in
sewers 250 to 600 mm (10 to 24 in.) in diameter. A total of 50 samples were tested by the Institute for
Underground Infrastructure (Institut für Unterirdische Infrastruktur gGmbH [IKT]) for: elastic modulus;
bending stiffness; thickness; and watertightness. No results were made available but, on the basis of the
results, Göttingen considers CIPP to have an effective service life of 50 years.
Public Utilities Board Singapore: They have carried out inspections of historic rehabilitation projects,
typically after about 10 years in service. The findings are shown in Table 8-12.
Table 8-12. Findings from Retrospective Samples of CIPP in Singapore
Location and Date Date
Installed
Inspected Diameter Thickness Length Data Collected
Upper Paya Lebar Rd 10/30/2008 225 mm NA 15.4 m Good condition (no
(1998)
defect)
Kim Seng Rd (2000) 08/26/2009 225 mm NA 34.3 m Good condition (no
defect)
Bishan Street 13 ( 1998) 05/29/2009 300 mm NA 43.5 m Good condition (no
defect)
Ubi Ave 1 btw blk
338/339 (1999)
02/09/2009 150 mm NA 64 m Bulging liner
Geylang Rd (1999)
NA = not available
05/30/2009 300 mm NA 37.8 m Longitudinal wrinkle
Queensland Urban Utilities - Brisbane: An installation from 1985 comprising 1.9 km of 12 mm thick
750 mm and 825 mm diameter lining was inspected in 2002, i.e., after 17 years of service. The inspection
was by CCTV only and no defects were noted. Since then several further inspections by CCTV and man
entry have been undertaken of this same line, and coupons taken. No defects were noted in the
inspection. Coupons have been retrieved from certain pipes when pieces have been dislodged by high
pressure jetting done for cleaning purposes, but have not been tested to establish their properties. This
has raised concerns over jetting for cleaning in CIPP-lined pipes.
8.6.2 Based on CCTV Inspections. Sydney undertook CCTV inspection of approximately 100 m
of 990 × 660 mm ovoid CIPP lining after 15 years of service. No significant defects were noted.
Leverkusen has undertaken CCTV inspections after 10 and 15 years in pipes from 250 to 1,200 mm
diameter and has not identified any specific problems that raise concern over the general performance of
CIPP liners. They also inspect liners as part of routine maintenance of their network. They plan to start
taking coupons and testing them in the future now that they have a larger program of CIPP works.
In general, the findings from these investigations after a period in service indicate that there is no serious
deterioration in performance of the CIPP linings. None of the findings has raised concerns over the
service life, and those defects found are often considered to be installation issues rather than inherent
weaknesses of the products themselves. The only exception to this is QUU’s concern over resistance to
jetting. This was also raised in Germany, where jetting is considered to be the reason for the general
failure of short liners.
8.6.3 Based on General Experience. Two of the utilities interviewed, Göttingen and PUB
Singapore, have a policy of trying to achieve a watertight sewerage system. Göttingen is more concerned
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