Underground Construction - February 2018 - 39

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For years, Municipalities have used Geographic
Information Systems (GIS) to map infrastructure
inventories and apply basic attribute information
such as material, size and construction date. Most
are using GIS to map PACP condition grades
in order to plan maintenance and rehabilitation
activities, develop capital plans, and apply condition
data as the Likelihood of Failure to asset risk
management analysis. Thinking outside the box
allows GIS professionals to map other PACP data
that is useful for Municipal planning.
Mapping Overall Pipe Ratings
Municipal staff and consultants must be properly
trained in PACP to accurately interpret inspection
results and understand the pipe ratings provided in
reports. There are up to 9 pipe ratings provided in
most PACP reports. Choosing the most appropriate
condition rating to map within GIS is important
to flag sewer sections requiring rehabilitation or
maintenance activities.
The result of thematically mapping pipe ratings
requires further analysis by reviewing the data
or watching the inspection video to determine
why a sewer section was assigned a specific
rating. In addition, CCTV inspection pictures and
videos, GIS or an above ground sketch should
be reviewed in order to assign the appropriate
rehabilitation method(s). Inspections represented in a
sophisticated GIS data model with links to the most
recent CCTV inspection report and video make the
review process much more efficient.
Mapping Individual Defects Observed Along
the Pipe
PACP-certified GIS staff will have the knowledge to
represent data accurately. To create an appropriate
data model, the application must consider the
following:
* Not all PACP codes are considered defects, and
separate layers are useful such as:
» Structural defect codes that typically use
the same rehabilitation methods and capital
budgets for repair.
» Operational and maintenance defects that
are typically managed through jetting, cutting
and reaming, and usually funded from the
operations budget.
» Non-defective construction features and
miscellaneous codes that give useful
information in terms of lateral locations, pipe
material and size changes. It should not be

necessary to map the typical first line of code
in PACP surveys (Access Point) as manholes
should already be represented within the GIS.
Unnecessary data can be filtered.
* Thematically mapping defects by type and/or
severity (condition grade).
* Using a linear referencing model, point defects
are represented as points along a sewer line and
continuous defects are represented as lines. Many
software incorrectly represent continuous defects
as two points; start and end of the defect.
* Codes observed in reversal surveys are correctly
referenced in the opposite direction from the
original survey.
* QA/QC checks which include:
» Upstream and downstream manholes in
inspection data exist within the GIS. This helps
identify typos in manhole IDs, duplication of
IDs, or incorrect mapping.
» The surveyed length is within acceptable
thresholds of the sewer length represented
in the GIS. This helps flag issues such as
incomplete surveys, unidentified manholes, and
improper mapping.
Mapping each line of PACP code observed allows
for more efficient and effective interpretations
and decision making. It is visually and spatially
understood instantly why a sewer segment has been
assigned a particular overall rating, lines requiring
maintenance versus rehabilitation, lines that require
spot repairs versus complete rehabilitation or
replacement, in addition to identifying maintenance
and repair programs by location.
Mapping Other PACP Data
Thinking outside the box to represent useful PACP
information within a GIS allows for better asset
management practices. Representation of condition
over time can determine sewers failing at faster
rates than others. On limited inspection budgets,
it may be useful to inspect sewer lines in poor
condition more frequently than those that are new.
Thematically mapping the Inspection Status field can
help to identify manholes that are buried, locked,
or inaccessible due to location or snow covered
during winter months and can help build a more
efficient inspection program. Identifying sewers that
repeatedly display Miscellaneous Survey Abandoned
code can flag potential problems with the sewer line
for more frequent maintenance or a required repair
that has been dismissed in urgency but inhibits
proper inspections in the future.
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Underground Construction - February 2018

Table of Contents for the Digital Edition of Underground Construction - February 2018
