Page 132 - Trenchless Technology Piping Installation and Inspection
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3.5 Planning and Site Investigations
Every pipe renewal project is unique and requires a careful site inves-
tigation before installation can begin. In the planning phase of a
project, surface and subsurface survey information provide assistance
in determining the suitability of the coating and lining methods.
Project owners must provide available existing pipe and site infor-
mation in the bid documents, so contractors can submit realistic
bids. Additionally, contractors must conduct their own surface and
subsurface investigations, as bid data might be outdated at the time
of bid submission and installation phase. Possibilities of unantici-
pated obstacles such as presence of debris, silt, and other deposits,
which may make the task of lining difficult, must specifically be
investigated.
Accurate information would lead to reduction of installation
problems, quality issues, reworks and change orders, and associated
social costs. The investigation of a lining site includes evaluation of
the number and condition of service laterals, easement restrictions,
potholing locations and regulations, and environmental concerns. A
surface and subsurface survey may include the following steps:
• Work area requirement
• Location of all existing utilities
• Utilities and structures adjacent to proposed pit locations
• Surface features, descriptions and layouts of roadways, side-
walks, and so on
• Visible subsurface utility landmarks such as fire hydrants,
valves, and so on
It is essential to determine all valve and fire hydrant locations
along the full length of the existing pipe. It is recommended that con-
tractor or installer physically check all the dimensions supplied by
the project owner in the form of drawings, videos and DVD’s, and
reports to ensure accuracy. Once surface and subsurface surveys are
completed, pit locations and thickness and section lengths of the lin-
ing installations can be determined. Proper site inspection is also
important for selection of appropriate lining parameters and deter-
mination of any modifications in lining design thickness.
3.6 Pipe Inspection
The main objective of pipe inspection is to examine the condition of the
existing pipe before and after liner installation. Closed-circuit televi-
sion (CCTV) is usually the method of choice to inspect the interior of
water pipes and also to evaluate quality of installed pipe. Valves,
water hydrants or other appropriate locations may be used as inspec-
tion insertion points.