Author: Professor, Dr. Dietrich Stein - TrenchlessOnline

in Miami-Dade, Fla.
of the water transmission and distribution
division.“We need to continue
to invest money to replace the infrastructure
because it is getting to be 50
to 60 years old or older. We have
water mains [in Miami-Dade] that
have been in service since the early
1930s. It is a challenge being faced by
not only Miami-Dade but every
utility across the United States
where the infrastructure is getting
to the point that unless we start
investing money in it, it’s going to
become catastrophic in the
future. And it’s not just the water
and sewer systems. Look at the
steam pipe that blew in New York
City and the bridge that collapsed
in Minnesota [this summer].”
Miami-Dade County is home to
the fifth largest utility in United
States, in terms of miles of service
and customers. MDWSD, with 440
sq miles of service area, maintains
7,100 miles of water lines and
3,600 miles of sewer lines, which
serve approximately 2.4 million
customers and includes 11 wholesale
municipalities.
The average age of the sewer
and water lines are 40 and 60-plus
years old, respectively, with some
sewer lines dating back as far as
1919.A majority of the sewer lines
are made of clay with new pipes
being fusible PVC; the forcemains
are made of ductile iron and prestressed
concrete. MDWSD operates
three water and wastewater
treatment plants each, along with 14
pump stations for water service and
954 pump stations for wastewater.
Trenchless Baptism
Trenchless methods made their first
appearance in the county in the early
1990s when fold-and-form (F/F) was
used to rehab aging sewer lines, as it
was considered more cost-effective at
the time than CIPP, says Lovett and
Aguiar.
“We did some successful fold-andform
programs,” Lovett says.“But now
we are pretty much exclusive to CIPP.
www.trenchlessonline.com
As we progressed, the patents on the
CIPP process wore off and as competition
came in, the price went down.
We have a contract now that we pay
$21.50 per foot for 8-in.CIPP,which is
actually less money than what we
were paying for fold-and-form.”
So far this year, Miami-Dade has
The Miami-Dade Water and Sewer Department completed more
than 40,000 ft of CIPP work so far in 2007.
done 40,600 ft of CIPP work.“That’s
probably down from previous years,”
Lovett notes. “We are going back
through the system [with inspection]
a second time; therefore we are not
finding as much of a problem as we
did the first time.”
Back in the early days when everything
trenchless was new, people
were coming out of the proverbial
woodwork, offering Miami-Dade
can’t-miss solutions and products to
its infrastructure problems. “About
that time, everyone was coming
down here with a magic wand, saying
‘I got the process that’s going to solve
all your problems,’” remembers
Aguiar, who at the time was working
on the sewer side. “It was then we
decided to hire a consultant and form
a committee so we could evaluate the
different processes and materials that
[were being pitched] to us… That is
how we started to expand our
trenchless program.”
The district’s trenchless program
has included over the years
a variety of methods and trenchless
companies, including some
large diameter and interceptor sliplining
work in the mid-1980s
using HOBAS pipe, a program that
lasted until the late 1990s. Pipe
bursting has been used on the
sewer side involving TT
Technologies but is being utilized
to a far larger extent on the water
side today.Televising and grouting
the sewer lines, once the main
cog in its trenchless arsenal, used
such companies as CUES. Regrouting
annular space for liners
added Logiball to the mix.
Today, CIPP continues to be the
most used trenchless method,
contracting the work out to such
companies as Insituform
Technologies. Laterals are taking
center stage these days with companies
such as LMK and Perma-
Liner among others getting the
call.
“Miami-Dade County Water and
Sewer has always been very conservative,”Aguiar
says.“It took a lot of
effort to accept technologies that
were really new to the U.S. market. So
we had to take certain chances.”
The televising and grouting program
was one such chance, using
technology that wasn’t largely accepted
by many utilities at the time.
Through the program, high levels of
I/I were vastly reduced over a fiveyear
period between 1993-98. The
program proved invaluable to
MDWSD and not just in terms of the
I/I results but in the knowledge
gained by its staff. “We had to learn
September 2007 TRENCHLESS TECHNOLOGY 21