Wastewater Utility (AWWU).
These case studies describe
field experiences with pipe
design, installation, costs,
and lessons learned.
Background
THE AGE AND type of materials used for transmission
and distribution mains can
vary widely. Older pipes
tend to be unlined cast
iron pipe (CIP), while newer
pipes include polyvinyl
chloride (PVC), high-density
polyethylene (HDPE), reinforced concrete
pipe (RCP), ductile iron pipe (DIP), or steel
lined with cement mortar (Table 1). PVC
pipe has been commercially available
since the 1950s and in widespread use
since the 1970s. HDPE pipe has been commonly installed since the 1990s.
The use of PVC and HDPE
water mains differs by
geographic location, the
prevalence of corrosive
soils, diverse pressure zones,
utility preferences and specifications, and seismic concerns. For example, in New
York City and Seattle, less
than 1% of installed pipe is
PVC or HDPE; ductile iron
is the preferred material of
construction. In contrast,
in the City of Calgary 56%
of the installed pipe is PVC.
In Japan, 32% of the installed pipe is PVC
(JWWA 2015) and installation of earth-
quake-resistant DIP is increasing. Some
utilities use plastic pipe for small pipelines
only; for example, the Golden State Water
Company in California finds that PVC is
less expensive than DIP because of ease
of installation for small pipelines up to
12 inches in diameter. The use of HDPE
pipe is increasing worldwide; most utility
surveys to date have limited HDPE data.
Case Studies
THE FOLLOWING FOUR case studies represent utilities of diverse size, geographic
location, and experience installing and
maintaining plastic pipe.
East Bay Municipal Utility District,
California
THE EAST BAY Municipal Utility District
(EBMUD) serves approximately 1. 3 million residents in the San Francisco Bay
area. Of the 4,200 miles of total water
mains, approximately 400 miles are PVC
and 10 miles are HDPE.
EBMUD has more than 30 years of
experience installing PVC pipelines
using a conservative approach. PVC
Table 1. Timeline of pipe technology in the United States
Material Joint
Corrosion Protection
1900 1910s 1920s 1930s 1940s 1950s 1960s 1970s 1980s 1990s
Interior Exterior
Steel Welded None None
Steel Welded Cement None
CIP (pit cast) Lead None None
CIP Lead None None
CIP Lead Cement None
CIP Leadite None None
CIP Leadite Cement None
CIP Rubber Cement None
DIP Rubber Cement None
DIP Rubber Cement PE Encasement
Asbestos Cement Rubber Material Material
RCP Rubber Material Material
Prestressed Concrete Rubber Material Material
PVC Rubber Material Material
HDPE Fused Material Material
Molecularly-orientedPVC Rubber Material Material
Legend: Commercially Available Predominantly in Use
THE USE of PVC
and HDPE water
mains differs by
geographic loca-
tion, the preva-
lence of corrosive
soils, diverse
pressure zones,
utility prefer-
ences and speci-
fications, and
seismic concerns
