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

7.0: RECOMMENDED TEST PROTOCOL FOR FUTURE USE
7.1 Overview of Protocol Implications
The experience in working with the cities of Denver and Columbus on the pilot studies in terms of
retrospective evaluation of CIPP liners was very useful. The research team found that there was strong
interest by the city engineers to participate, especially when sample retrieval could be combined with
other activities that the city needed to undertake. In this section, the cost implications of the study for the
utility participants are discussed. The field and laboratory experiences and the usefulness of the test
results in terms of understanding the expected life of CIPP pipe rehabilitation are summarized. This
information is then used to discuss the technical feasibility of a broader national program for the
retrospective evaluation of CIPP liners, as well as similar programs for other rehabilitation technologies.
7.2 Fieldwork Costs
Each of the cities that participated in the pilot program contributed much or all of the costs for the
fieldwork in retrieving either CIPP liner samples alone (from larger diameter pipes) or a full sample of
CIPP liner including the host pipe (in both cases these were from 8-in. diameter pipes). The costs
incurred for the fieldwork are provided below. These costs do not include the planning and coordination
costs for the city engineers and other staff that were involved in the discussions regarding participation in
the study and the set up of the field tests.
Based on the experiences to date, the direct costs to a municipality to retrieve an approximately 6-ft long
sample of 8-in. diameter lined pipe in a relatively low traffic area can be in the range of $10,000 to
$25,000 when combined with other activities at the same site (e.g., sewer line replacement or pavement
replacement at the site). Costs for person entry into a larger diameter sewer and retrieval of a sample of
the liner only were much less expensive in terms of direct cost, amounting to approximately $1,600 to
$3,500 in the pilot studies. These are preliminary estimates since actual costs will vary with many factors
including: cost profile of city and of location within the city (e.g., downtown, suburban, etc.), depth and
diameter of line evaluated, ease of access, and combination of evaluation with other planned work.
7.2.1 City of Denver Costs. The City of Denver was the first city that the research team
approached. In order to explain what was being proposed, a preliminary draft of the expected evaluation
activities and protocol was prepared for use in the discussion with the city engineers (see Section 2).
After exchanging information by phone and e-mail, a one-half day meeting was held in Denver with the
city engineering team (Wayne Querry and Randy Schnicker) after a suitable site for a retrieval of a liner
plus host pipe segment had been identified. The main determinants for site selection for the sample
retrieval were that the CIPP liner should be one of the oldest liners in the City and that the pavement
above the pipe should be in need of replacement (so that it could be paid for by agreement with the City
department responsible for paving). Following the meeting, the City collected the background
information on the proposed site and made arrangements for field work for the 8-in. host pipe and liner
retrieval. Since the sample to be retrieved was in an alley, there were no special costs for traffic control.
The second sample location was chosen because it was an old CIPP liner and because a sample had
previously been removed from the same site for an evaluation in 1995. Dig-up was not considered
feasible for the evaluation because of the cost and disruption in a busy city location and because of the
need for bypassing of the line. Instead, an active local CIPP contractor was identified that would enter the
sewer line to retrieve the liner sample. Because of their interest in the findings, the contractor did the
work at a below-market rate.
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