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August 2017
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City of Morgan Hill
Sewer System Master Plan
Other structural defects (PACP Rating 1-3), were used in the process of evaluating how critical
the individual pipe segments were.
The major structural defects were documented on
Figure 7.6
. The individual defects included
broken or deformed pipes, holes in the pipe, collapsed pipes, or obstructions located within the
pipe. These defects are indicators that pipelines have already failed or are in imminent danger of
failing.
Infiltration and inflow defects were also documented as part of this analysis and included on
Figure 7.7
and
Figure 7.8
. These defects can lead to sanitary sewer overflows, premature
pipeline upsizing and higher treatment costs.
7.5.3
Improvement Recommendations
Improvements recommendations were developed based on the findings of the condition
assessment. As pipelines fail to varying degrees and in various locations, the improvement
recommendations were grouped by the following criteria:
x
Risk.
This category is based on the failure type and location to critical places, such as
schools or creeks.
x
Location.
To avoid costly mobilization and adverse public interference, improvements
were grouped into confined neighborhoods.
x
Cost.
Pipelines were also grouped by cost. As it may be cost prohibitive to complete a
City-wide rehabilitation and replacement program, improvements were grouped to
maintain an annual reasonable cost for budgeting purposes.
The project groupings are documented in
Appendix C
. Once groups were created, they were
prioritized by the overall risk of the group, and proximity to other groups.
Additionally, City staff identified priority sections of pipeline intended to be replaced in the near-
term due to deteriorated conditions or operational considerations (
Table 7.2
). It should be noted
that, for planning purposes, the operational improvements generally involve replacing pipes in
kind. These improvements are described as follows:
x
RP-P1
: Replace the existing 6-inch gravity sewer located on right-of-way along Holiday
Drive to Oak Lane. This improvement is meant to mitigate the existing sag in the gravity
main that could cause flows to spill into the adjacent lake. It should be noted that this
pipeline is planned for rehabilitation and is shown on the condition assessment exhibits
included in
Appendix C
.
x
RP-P2
: Replace the existing 6-inch gravity sewer along Wright Avenue from 230 feet east
of Garden Avenue to Del Monte Avenue. This improvement is meant to repair the existing
gravity main that is currently broken.