For municipalities and municipal utility authorities truggling to deal with corrosion issues, knowing where to turn when faced with these challenges
can be daunting. Logan Township Municipal Utilities Authority (MUA) of New Jersey was faced with such problems when
a fve-year-old stainless steel headworks tank at its wastewater treatment facility was experiencing extreme Microbiological Induced Corrosion (MIC) at the waterline with corrosion
severe enough to open holes through the tank wall. The 304
stainless steel tank was no longer covered by the tank manufacturer’s warranty, and the manufacturer didn’t offer any
satisfactory solutions to rectify the corrosion issues.
The problem became even more complicated for MUA
when a selected lining system was discontinued by the coatings manufacturer just one week prior to installation. Unsure
of where to go next, it contacted Corrosion Technology
Systems Inc., a manufacturer’s
representative for Sauereisen
Inc. of Pittsburgh, Pa. MUA
needed help identifying an
engineered solution, fnding a
and securing on-site support
to ensure the project was completed successfully.
Logan Township MUA, located in Gloucester County on
the Delaware River, has a population of just over 6,000. A
working class community, it boasts a unique mixture of resi-
dential, farmland, commercial, industrial, and retail areas
within its 23 square miles. While many other MUAs are fac-
ing reductions in their infrastructure and repair budgets, Lo-
gan Township MUA, through prudent fscal management and
good stewardship of rate payers’ dollars, provides its custom-
ers with a consistent level of services with predictable cost.
MUA discharges only the highest quality effuent back into
the Delaware River and has received several awards from the
New Jersey Department of Environmental Protection as well
as the Environmental Protection Agency (EPA) recognizing its
The wastewater treatment process begins at the headworks
structure. A complex network brings raw wastewater into the
facility via miles of underground piping from the municipal-
ity’s collection system and from septage waste delivered by
truck. The headworks structure can be concrete or steel and
can be located either below-grade or aboveground. Its prima-
ry function is to remove debris such as solids, paper, sand and
grit, metals, plastic, etc., before sending the infuent stream
to the equalization tank for distribution to one of MUA’s four
biological treatment units. It is the frst step in the process of
reducing the level of pollutants in the wastewater stream.
It was in this frst stage of the treatment process that MUA
noticed problems that allowed raw wastewater to leach out of
the aboveground structure, creating potential health hazards
and unsanitary conditions around the stainless steel tank.
Logan Township MUA learned the hard way that not all
stainless steel is equal and that the grade and surface fnish will determine the ability of the stainless steel to function
properly for its intended use. Making the situation worse, the
57-foot-long, 10-foot-deep, and 6-foot-wide tank had several solid stainless steel hatches that trapped H2S within the
unit above the waterline.
Testing by MUA was very minimal; however the sulfde tests
that were run showed low levels of sulfdes. The investigation revealed that the tank was constructed of 304 grade stainless steel,
which is not suffcient enough to provide the necessary protection required in this environment. Stainless steel is a corrosion-resistant steel alloy with a minimum of 10.5% chromium content by weight. The most common austenite steel is 304 stainless steel with a composition of 18% chromium and 8% nickel.
It is not supposed to corrode or rust like common carbon steel.
However, under specifc conditions — such as 100% O2 environments or containment with poor circulation, as is the case at
Logan Township MUA — 304 stainless steel can corrode. Higher grade stainless, with suffcient chromium, will form a pas-
Above-grade stainless steel headworks tank at Logan Township MUA.
Stainless steel tank wall with holes resulting from MIC.
Water Authority Protects Stainless Steel Structure
from Future Degradation
BY JON C. LATTIN AND JOHN E. DAVIS