| Contra
Costa Water District has
over 800 miles of pipeline in the ground,
of which are about 20 miles of steel pipeline
are installed in high traffic areas, with
limited or no cathodic protection The objective
of this assessment was to identify the corrosion
protection needs to prolong the service
life and system reliability of approximately
20 miles of steel pipelines. The pipelines
of concern were installed between 1950 to
1995, with limited or no corrosion protection,
and most are located in high traffic areas
making repairs difficult. Most of these
pipelines were installed with rubber gasket
joints (not welded), which make the pipelines
electrically discontinuous and expensive
to retrofit with corrosion protection. |
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Excavation
location at failure site of a 20”
concrete cylinder pipeline |
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| This
assessment included an evaluation of soil
and pipe characteristics to identify which
pipelines were most susceptible to corrosion.
The subject pipelines are primarily mortar-coated
steel or asphaltic-coated steel pipe. There
are also two short sections of ductile iron
pipelines. Sections of pipe in areas with
highly corrosive soils were excavated and
examined. The pipeline contract drawings
were reviewed in order to determine the
steps that were taken during the original
construction to protect the pipe, such as
applying cement mortar coating over dielectric-coated
steel at pipeline joints.
This
was a very large project with a significant
budget and a challenging schedule. Our firm
completed this project on-time and under
budget. |
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Water
is leaking from the vertical crack
on the north side of the pipe. |
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Client:
Zone 7 Water
Agency
Project: Development of an Overall Corrosion
Control Program & Develop a GPS Coordinate
Data Base for All Test Stations and Cathodic
Protection System Components
This project
involved the development and implementation
of a comprehensive corrosion control program
for the Zone 7 Water Agency. The Zone 7
Water Agency facilities/structures consist
of 2 water treatment plants as well as over
50 miles of water transmission pipelines
of various diameters, several clearwells,
and numerous water wells and water storage
tanks. The Zone 7 Water Agency cathodic
protection system consists of both impressed
current and galvanic anode systems. All
of the major mortar-coated steel transmission
pipelines are provided with either a cathodic
protection |
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Del Valle Water
Treatment Plant was one of two water
treatment plants included in our development
of a comprehensive control program
for Zone 7 Water Agency.
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A
GPS coordinate database was created for
all coal tar coated steel pipelines and
the corrosion monitoring systems for the
cement mortar coated steel pipelines owned
and operated by the Alameda County Flood
Control and Water Conservation District,
Zone 7 Water Agency. The structures covered
by this project are located in Dublin, Pleasanton
and Livermore, CA. The cathodic protection
systems consist of a combination of impressed
current and sacrificial anode type cathodic
protection systems for external corrosion
protection of the pipelines. The structures
which were surveyed and included as a part
of this database consisted of approximately
160,000 feet of water transmission pipeline.
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Sample
of pipe-to-soil potential data from
four different surveys graphed for
comparison purposes. |
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Client: LAVWMA
Project: Inspect Internal Coating System
for Export Pipeline
Our firm conducted a coating evaluation
of the interior of the export pipeline
for LAVWMA. The purpose for this inspection
was to assess the condition of the western
most section of the LAVWMA Export Pipeline
where it extends into the marshland area
and connects to the East Bay Dischargers
Authority (EBDA) interceptor in San Lorenzo.
This condition assessment consisted of
internal inspection of the pipeline via
four vaults. The coal tar enamel lining
was disbonded from the interior surfaces
of the pipeline in large areas (reportedly
up to 50% loss of coating coverage) and
the underlying steel pipe was actively
corroding at a rate which is common for
all mild steels when exposed to fresh
water.
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Interior coating damage on LAVWMA
Export Pipeline.
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