HOBAS pipes were
utilized on two major phases of a wastewater piping project in
Odessa, TX. One phase included expansion of the East Water
Reclamation Plant (EWRP) to prepare for increased flows. The other
phase was the construction of a transfer line which diverts flow
to the EWRP from the South Dixie Water Reclamation Plant (SDWRP),
which was to be abandoned.
Limited Specification
The specifying engineers for the EWRP modifications were Landgraf,
Crutcher and Associates, Inc. (LCA) of Odessa, TX and Alan Plummer
and Associates, Inc. (APA) of Fort Worth, TX. The engineers'
specifications allowed both HOBAS pipes and ductile iron pipes
although, due to the corrosive environment, D.I. pipes were
required to have an epoxy-lining as well as a complete
polyethylene encasement bag for direct burial. HOBAS pipes did not
require additional linings or coatings due to their inherent
corrosion resistance which results in superior performance in
acidic conditions (such as those found in many sanitary sewers).
Either low pressure air or hydrostatic field testing was required
to ensure integrity of line after installation.
Special Aerial Design
The installation contractor for the Bob Derrington Water
Reclamation Plant (new name for the modified EWRP) was The
Hardaway Company of Tampa, FL. Approximately 7,000 ft. of 46 psi
stiffness pipe ranging from 18" to 54" was supplied with
HOBAS gasket-sealed FWC couplings for installation by direct bury.
Many fittings were fabricated for the treatment plant including
lateral wyes, tees, elbows, reducers and flanges. A specially
designed 48 inch diameter, 72 psi stiffness pipe was manufactured
for the sanitary sewage aerial installation. The two parallel
above ground lines totaled 1,740 ft. and were placed on concrete
cradles spaced at approximately 20 ft. centers. The aerial
included a 90 degree turn which required fabrication of two
special elbows (one long and one short radius) to maintain the
parallel alignment.
Engineered Product
The Odessa Transfer Sewer Interceptor, which diverts the sewage
from the South Dixie plant to the new Bob Derrington plant,
includes over 7 miles of 54" and 48" pipe which is being
installed by Oscar Renda Contracting, Inc., of Roanoke, TX. The
majority of the pipe was installed by direct bury at cover depths
of up to 28 ft. Other installations included 3,200 ft. of 54"
500 ton flush joint pipe installed by jacking and approximately
300 ft. in a casing. The open cut pipe stiffness classes ranged
from 18 psi to 72 psi, changing as appropriate with increased
depth, resulting in the safest, least costly installation. Since
HOBAS is an engineered product, different stiffness classes or
jacking tonnages are easily manufactured to meet job specific
design criteria economically.
Meets ASTM Specs
LCA and APA were also the engineers for the Odessa Transfer Sewer
and again specified corrosion resistant piping products, due to
the anticipated acidic environment including; fiberglass
reinforced pipes (FRP), ductile iron pipes with a 40 mil
polyethylene liner (DI-PE), and reinforced concrete pipes with 360
degree T-lock lining (RCP-PVC). The specifications required that
all materials conform to various ASTM and AWWA standards.
All Fiberglass MH's
Over 30 HOBAS T-base manholes, both straight and P.I., were
supplied with 30 in. riser stubs to receive 48" diameter
fiberglass manholes manufactured by L.F. Manufacturing of
Giddings, TX. Due to our unique fabrication process the T-base
sections were fabricated to exactly the angle required whether it
be 88 degrees left or 4 degrees right. Since the manholes are
manufactured from either straight or mitered sections of our
centrifugally cast pipe, they were easily joined into the line
with the FWC coupling to create a completely gasket-sealed HOBAS
system.
High Performance
The HOBAS fiberglass sleeve couplings (FWC), which utilize
elastomeric sealing gaskets made of EPDM rubber, contributed to
the rapid laying rates and resulted in the absolutely leakfree
joints achieved on the transfer line. Almost 1,000 joints (19,000
ft.) of 48 in. diameter pipe were laid in 30 days. Even with the
accelerated laying rate, HOBAS pipe joints were air tested at 3.5
psi with a 100% pass rate on the first test. In fact, the pressure
tests showed no leaks at all, exhibiting zero pressure drop during
the test period. Deflection tests revealed that most of the pipe
has less than 1% deflection with the maximum being 1.5%.
(Considerably less than the recommended maximum of 5%.) Oscar
Renda Contracting is very happy with the performance of the HOBAS
pipes and the user friendly installation, even under accelerated
laying conditions
