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Missouri-based Environmental Dynamics, Inc. (EDI) has twenty-seven years
of experience manufacturing innovative wastewater treatment systems.
The company is an integrated manufacturer of diffused aeration systems
including diffuser technology, research and development, system engineering,
and product manufacturing. The backbone of their systems is PVC pipe.
The systems use aeration to treat wastewater; aeration relies on the
natural removal of harmful materials using microorganisms requiring
"If you have ever had a fish tank, you're familiar with the use
of a "bubbler" to aerate the water," says EDI Executive
Vice President Randy Chann. "The principle is the same. EDI systems
use oxygen in the atmosphere blown through a carrier pipe - PVC - to
The use of a diffuser - a mechanical device that puts oxygen into water
- is a common approach to water treatment. EDI's systems use mechanical
aerators fitted with a special, flexible membrane to provide fine pore
diffused aeration. The finer the bubbles created by the system, the
greater the system's efficiency. PVC manifolds and headers provide the
structural grid to hold EDI diffusers & membranes. The diffusers
themselves are essentially mini systems of PVC with specific openings
to feed flexible membrane.
The result is a remarkable PVC structure. The largest plants treat
over 100 million gallons of wastewater per day. In each of these plants,
the amount of PVC piping employed in the air distribution system and
diffuser components is over 60,000 feet. In addition, each plant uses
numerous fittings, tees, ells, caps, flanges etc. On large jobs this
amounts to well over 2000 to 3000 miscellaneous fittings.
PVC DWV SYSTEMS AFTER 20-PLUS YEARS OF
The earliest report this author found describing a PVC water pipe installation
dates to 1934 in Germany. In 1950 a plastics pipe trade association
was founded in the United States, and in 1951 a plastics evaluation
program began at the Michigan School of Public Health. That four-year
program included animal feeding studies and an impartial study of plastic
pipe from a public health point of view.
In 1957 the US
Department of Commerce published a Commercial Standard (CS 207 - 57)
for PVC pipe. ASTM Standard (D 1785 - 60) followed in 1960. Other PVC
pressure pipe standards followed (CS 256 - 63 in1963 and ASTM D 2241
- 64 in 1964) along with PVC - DWV Pipe and Fittings Standards (CS 272
- 65 and D 2665 - 68) in 1965 and 1968 respectively. PVC piping installed
during and after those dates may be marked with those standard numbers.
PVC DWV systems have been installed in multi-story buildings for more
than twenty years. When these early installations were made in the late
1960s and 1970s, a list was compiled of 51 buildings in 31 cities. This
article reports findings from 1998 inspections of six of these early
installations, along with confirmations that the systems continue in
operation at this time.
Headquarters Building in Washington, DC
This seven-story building was built in 1973. New chillers were being
installed and the air handling system was being revised at the time
of the 1998 inspection. The DWV and roof drain systems are PVC and have
been trouble free. Very little of this piping is visible except in the
seventh floor mechanical room where drain and vent pipes were observed.
Some of them had expansion joints. Exposed cooling tower piping out
on the roof had faded in color to nearly white. Mr. Pierre Rahel has
been Building Manager for the last two years and Mr. Sid Cox has been
the Building Engineer for the last seven years. They report that their
PVC piping systems continue to perform satisfactorily.
in Washington, DC
This nine-story apartment building was built in 1973. The DWV system
and the storm water drains are PVC. Robert Ducket has been the Maintenance
Supervisor for about fifteen years. His staff uses normal preventive
maintenance procedures and has had no problems with the PVC piping.
in Washington, DC
Stevens Company, Plumbing and Heating has done all the service work
on the piping systems and has records of all the maintenance that has
been required on this condominium. Some cracks have appeared in Tee/Wyes,
but the company noted that these occurred when the branch line was not
properly supported. Some cracks have also appeared in flanges, but otherwise
the systems are working well.
uses a lot of plastic pipe in their repair and new work and reported
that in its experience:
· Stoppages are about the same in cast iron pipe as in plastic
· Piping laid against drywall creates sound problems.
· Screws and nails can penetrate piping. (This occurred mostly
Condo in Arlington, VA
At the time of the 1998 inspection the metallic hot water piping and
the hot water heating system were subject to pinhole leaks (common in
these metallic systems). Roberto Suarez who had been the Building Maintenance
Supervisor for five years provided information about other plumbing
systems. He reported that system maintenance had been normal except
for one incident when a heavy rainstorm resulted in a complete separation
of a pipe/socket joint in a 6-inch roof drain leader. This flooded the
lobby area. No other information was available concerning the cause
of this failure in a gravity flow pipe in service for years with no
sign of leakage. Since 1998 management has made some improvements to
the heating system, but continue to have water-piping leaks. The PVC
systems continued in service without problems.
- Without seeing the 6" joint that separated, but based on some
past experiences, this joint could have been primed and assembled during
the "fitting up" process but then never solvent cemented.
This type of joint separation has been reported by others and has even
occurred with pressure pipe. If anyone reading this has first hand information,
please call Robert C. Wilging at (440) 933-4394).
in McLean (Tyson Corners), VA
This nine-story building has cast iron stacks and PVC branch piping.
There have been no problems with the PVC piping, and system maintenance
has been normal. Some PVC has been used in remodeling and in a new building.
Chief Engineer Barry Singh reported that about four years ago a CPVC
fire sprinkler system was installed without any problems and is operating
at 150 psi.
As of December
2000, all systems continue in service. However, one underslab line failed
because the fill consolidated and caused a break in the line.
Park Layne in
This eleven-story luxury apartment building was built in 1969 and was
mentioned in the October 1970 issue of Building Systems Design magazine.
The article refers to a "marriage" of PVC DWV and cast iron
in the drainage systems.
reference applies to the Park Layne installation where PVC pipe 3-inches
and smaller was used for all of the kitchen, lavatory and tub drains
plus some of the shower drains. Cast iron vent pipes were used in the
lower six stories, and PVC was used for the remainder of the vent piping.
The PVC pipes are caulked into cast iron fitting hubs with oakum and
lead wool. These joints were made without PVC molded adapters and have
been trouble free.
During the same
time, some of the cast iron pipe and fittings have developed corrosion
leaks. Although epoxy patches can provide temporary relief for small
leaks, replacing leaking pipe and fittings with PVC is a permanent solution.
Shower drain leaks have been resolved by breaking out the concrete base,
removing the cast iron drain piping and installing a new PVC drain line
and a shower base. The PVC pipe is easy to cut, fit and join. Based
on experience with PVC piping that has been in service for 30 years,
these PVC shower drains appear to solve the corrosion problem.
The Park Layne
with 128 apartments and two additional buildings, The Riverstone and
The Rockwood, are owned and operated by Towne Asset Management Co. Larry
Rainwater has been in the apartment maintenance field for 25 years and
has had responsibility for all three buildings for three years. Based
on his experience with all three buildings, Rainwater believes that
his piping maintenance job would be easier if PVC DWV piping had been
installed throughout. He also maintains the swimming pools and had has
found the PVC piping used there has served well.
During the 1998 inspection, Larry Rainwater noted that he sometimes
goes through a section of PVC pipe with mechanical cleaning equipment
to reach a section of cast iron pipe. (Author's note: A brief report
about tests done years ago using RotoRooter equipment showed that the
cleaning tools passed through PVC bends without damage to the plastic
fitting.) Rainwater referred this inspector to Alan Pierce Sr. who has
operated a RotoRooter franchise for 40 years. Based on his experience,
Pierce offered the following comments on PVC maintenance with mechanical
· Acid and caustic drain cleaners, if used continually, will
attack and destroy metal pipe, because after the metal is cleaned corrosion
· Thin-wall PVC sewer pipe can be cracked by the whipping action
of a sewer snake.
· Schedule 40 PVC DWV pipe and PVC sewer pipe are not affected
by mechanical cleaning equipment.
· The gases inside DWV and sewer pipes create corrosive conditions
that destroy metals over time.
· After some brief exposure to sulfuric acid, sewer snakes broke
cast iron with brittle fractures even though they were only in service
a short time.
· Proper sewer pipe installation is a major factor in obtaining
a long service life regardless of what sewer pipe material is used.
Although these inspections did not yield any significant new information,
they did verify that PVC's corrosion resistance is a primary factor
in its ability to provide many years of trouble free service in both
DWV and sewer systems.
If any readers
have information that will further this effort your response to the
Editor would be appreciated.