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

The benefits of the Quebec study were seen to be that rumors about rehabilitation performance can be
addressed and that information critical to life cycle analysis of rehabilitation efforts could be collected.
A strategic decision was made in the study to cover as much of the rehabilitation work as possible so that
the general condition of rehabilitated lines and any visible defects could be identified. This led to the
broad use of CCTV for the assessment work. Specific samples were to be collected for quantitative
analysis based on a review of the CCTV data and the available budget. A survey was sent out to the
municipal participants to establish how many meters of rehabilitation had been accomplished in each
municipality. The survey was also sent to contractors with the promise to keep the data as confidential as
possible.
On the water rehabilitation side, the collection of data on rehabilitated lines had been relatively simple
since there were only two contractors doing the water rehabilitation work. On the sewer side, the
situation was more complex. The contractors had changed over time and there was a need to provide
even representation in the study.
Some cities had already conducted a 10-year evaluation of their own rehabilitation program, e.g., Quebec
City for CIPP relining. CERIU had conducted a review of 12 techniques for manhole rehabilitation in
1999 and had followed up with further evaluation in 2004 and 2009. The evaluation techniques used
were visual inspection plus hammer tapping to identify liner defects. The results of the inspection were
good and a report was to be released soon.
The universities participating in the current retrospective evaluation were focused on physical sampling
for CIPP and pull-in-place liners, etc., but the budget was very limited. The committees for the project
were making decisions about what should take precedence: inspection, sampling, or testing.
Many cities have done prior CCTV inspection. Montreal has 20-year old grouting rehabilitation of
manholes and mainlines that was recently been reinspected by CCTV in October 2009.
Physical samples for sewer lines were planned to be retrieved principally from person-accessible
locations (adjacent to manholes, person-entry diameter pipes, etc.). Concordia University was to do the
testing and analysis. Both destructive and NDT methods were to be used. Some of the test parameters
were to include: Manning’s coefficient, liner/sample dimensions, ease of repair, permeability at
connections, flow, and pressure. Most municipalities have before and after CCTV scans for the
rehabilitation. Some municipalities have follow-up CCTV one and five years later.
Some of the municipalities involved in the Province study have mostly done grouting work and some
mostly CIPP. Two pipe groups were anticipated for sample retrieval for water mains: 6 in. diameter and
less and greater than 6 in. diameter. One meter long samples were expected in a full pipe sample
retrieval. Studies of grouting effectiveness were planned to be done by internal pressure testing. Where
the section would not pass, excavation was planned to see if a grout ball exists outside the pipe at this
location.
Testing specifics anticipated were:
• Evidence of water leakage
• General state
• Hazen-Williams coefficient data (static and dynamic testing)
• Water connection integrity
• Pressure and flow data
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