Download - Water Utility Infrastructure Management

Protective Coating
for Wastewater
Facility Concrete
Surfaces —
Best Practices
Coatings can be an efficient and cost-effective
technical solution for protecting and renewing
sanitary sewer tanks, pipelines and appurtenances.
Asset management principles and practices
require wastewater utilities to look beyond the initial
cost and focus more on long-term solutions and lower
life-cycle costs. Premature failures of coatings have generated
much concern regarding true life-cycle costs.
Concrete coating systems for wastewater service must
typically withstand immersion, harsh chemicals, abrasion,
low pH and other challenging conditions. Premature
coating failure is significantly higher with concrete than
with steel, for example, due to several additional variables
including moisture content, surface strength, surface
irregularity, alkalinity, composition and porosity,
which results in a difficult surface to effectively coat and
protect. Other factors include surface preparation and
coating system mixing, application and curing practices,
to name only a few.
Some of the most common concrete coating system
defects and failure mechanisms in wastewater applications
are:
• Osmotic blistering
• Pinholes and voids
• Peeling
These failures or defects will typically lead to premature
concrete damage, compromising structure integrity
and personnel safety and necessitating costly repair and
premature infrastructure replacement.
Many concrete coating products for wastewater service
exist in the marketplace and new products are entering
the market frequently. This paper provides a review of the
importance of product and process validation and presents
recommendations and lessons learned in specifying,
applying and utilizing these products over the past 20
years.
By Jeff Maxcy and Tom Iseley
Product Evaluation and Validation
Product evaluation and validation is not a new concept,
and has been demonstrated to be an important factor in
achieving success. It provides the benefit of using materials
that have already proven to be effective in similar
applications.
Owner representatives and consulting engineers have
for many years realized the importance of reviewing new
products and processes. Most of the larger utilities with
support from consultants have developed product review
committees (PRCs). However, small- to medium-size utilities
tend to have no formal process. Even for utilities with
PRCs, the review, validation and acceptance/rejection
tend to vary significantly from agency to agency. Often
this process is time-consuming, awkward, inconsistent,
subject to political influence and expensive. This wide
variance in how decisions are made to accept/reject products
and processes results in major challenges and
expense for the technical solution providers.
In 2009, the City of Indianapolis and the Construction
Engineering Management Technology (CEMT) program
at the Purdue School of Engineering and Technology at
IUPUI entered into a collaborative agreement that resulted
in development of a 10-step new product review process.
To date, more than 15 products have been evaluated
through this innovative process at no expense to the City.
The technology providers pay a fee. This program has
been very successful. During 2010, both Fort Wayne, Ind.,
and Zionsville, Ind., have entered into similar agreements
with the university.
Due to the strong interest in the new product review
process from utilities and consultants across the nation, a
new program will be launched to provide access to all new
product review reports on a subscription basis. The nonprofit
Institute of Product Validation (IPV) (www.institutepv.com)
has been formed to manage the national
program. Any utility or industry representative can subscribe
to the IPV services and access the new product
36 Water Utility Infrastructure Management
November/December 2011