Author: Professor, Dr. Dietrich Stein - TrenchlessOnline

Through two pilot programs, more than
1,600 laterals have been inspected and
subsequently 1,000 rehabbed to this
point. The county used a sanitary sewer
evaluation survey (SSES) to assess the
pipes’ condition. SSES uses various equipment
and techniques to detect sewer
pipe defects, blockages and capacity
problems. These techniques include
smoke tests, dye tests, closed-circuit TV
(CCTV), flow monitoring, rain monitoring,
building service connection location/inspection
and flow isolation.
“We did the pilot programs to try to
identify the source of rain-induced I/I that
comes into the system during and after
heavy rains,” says Lovett.“We are looking
closely now at extending the program.”
The project is designed to evaluate a
variety of lining systems, including CIPP
and inner seals. In addition to testing
these products, Miami-Dade is fine-tuning
its flow monitoring techniques to ensure
accurate measurements of the reduction
of infiltration.
The first and smaller pilot program
goes back five years and involved three
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basins and 99 laterals. The second
and larger program recently
wrapped up and involved 52 basins
and 1,600 laterals.Estimated cost for
the larger program is $16.5 million,
with actual costs being about $14
million. “The only thing we don’t
have on the second program is the
rainfall data on some of the basins
yet because we haven’t had enough
Circle 9 on reader service card.
rainfall to compare the results,”
Lovett says, explaining that a “qualified
rain event” is one in which at
least 4 ½ in. of rain falls in a 24-hour
period. “We typically get several of
those during our rainy season but it
hasn’t occurred across the county as
a whole;it’s been spotty in the county.
We have been able to qualify
some basins, not all.
September 2007 TRENCHLESS TECHNOLOGY 23