United States
Environmental Protection
Agency
RESEARCH PROJECT
National Risk Management Research Laboratory
Water Supply and Water Resources Division
Treatment Technology Evaluation Branch
ANALYSIS OF DISTRIBUTION SYSTEM AND DOMESTIC SERVICE LINE PIPE DEPOSITS TO
UNDERSTAND WATER TREATMENT/METAL RELEASE RELATIONSHIPS
IMPACT STATEMENT
Understanding the water treatment systems and the
chemistry of metal release from plumbing will help to solve
corrosion control, improve water treatment and resolve
regulatory compliance problems for specific utilities in the
U.S. Environmental Protection Agency's (EPA) technical
support role. This project will work to improve the basis for
water chemistry modeling to better predict metal release,
corrosion behavior, and treatment change impacts so that
replaced water infrastructure will not have the same life-
cycle problems as existing systems. EPA will be able to
better educate utilities, consultants, and regulators, which
will prevent treatment mistakes due to overlooked
problems with the new water systems.
BACKGROUND:
In 1989, this project was started in an effort to corroborate the results of efforts to predict the corrosivity of drinking
waters to large distribution system infrastructure materials and premise plumbing. Early results revealed significant
surprises in the composition of protective pipe scales, which often differed from assumptions that had been made about
operable corrosion control and scaling mechanisms. Notable examples include the importance of tetravalent lead
deposits in mitigating plumbosolvency in many water systems; the critical role of iron, manganese, and aluminum solids
in scavenging trace metals and radionuclides; and affecting corrosion and release of lead and copper were revealed. The
program is also involved with following the physical and mineralogical evolution of pipe deposits in response to
corrosion control or other treatment changes, to develop or corroborate corrosion and corrosion control theories.
DESCRIPTION:
The Office of Research and Development's National Risk Management Research Laboratory has funded this research
project in support of its Aging Water Infrastructure (AWI) Research Program. Samples tested for this research include
pipe samples, scales from storage tanks, failed plumbing devices and distribution system sediments. These samples are
obtained through technical support efforts by water systems, consultants, state regulators, and EPA regional offices.
Solids analysis performed on these samples are primarily done in-house by on-site contractors. Tests performed by the
on-site contractors include optical mineralogy; photomicroscopy; sample preparation; scanning electron
microscopy/energy dispersive x-ray spectrometer/wavelength dispersive x-ray spectrometer (under development); X-ray
diffraction (XRD); X-ray fluorescence (under development); total carbon (TC); total sulfur (TS); and total inorganic carbon
(TIC). Tests performed through an interagency agreement with the U.S. Geological Survey include digestion and
elemental analysis for 40+ metal and rare-earth elements; capability for mercury; capability for LA-ICP-AES/MS; and
backup tests for TC, TS, and TIC.
Chemical speciation of scale materials and corroboration of some XRD results is also determined for some projects using
synchrotron methods such as X-ray Absorption Near-Edge Spectroscopy and X-ray Absorption Fine Structure
National Risk Management Research Laboratory
Water Supply and Water Resources Division
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spectroscopy using the facilities at the Argonne National Laboratory Advanced Photon Source. The results of these
analyses are used to deduce operable corrosion, corrosion inhibition, metal accumulation and metal release
mechanisms occurring in different water systems, or to predict the impact of various proposed changes in disinfection or
other treatments on the stability of existing pipe scales and deposits.
This project puts EPA into a unique position of being able to bring analytical tools to bear to solve or anticipate future
drinking water infrastructure water quality and metallic or cement material performance problems for which little
application expertise for drinking water systems exists in either universities or the private sector.
EPA GOAL: Goal #2 - Clean & Safe Water, Objective 2.1.1- Water Safe to Drink
ORD MULTI YEAR PLAN: Drinking Water (DW), Long Term Goal - DW-2 Control, Manage, and Mitigate Health Risks
RESEARCH PARTNERS:
Collaboration: Municipal water systems, consulting firms, state drinking water programs, and EPA Regional Offices
Contractors: Pegasus Technical Services; Battelle (Columbus)
Supporting Agencies: U. S. Geological Survey (Interagency Agreement); U. S. Department of Energy (facilities accessed at the
Advanced Photon Source, Argonne National Laboratory)
EXPECTED OUTCOMES AND IMPACTS:
This research project is expected to improve water chemistry modeling to predict metal release due to various
operational changes. This improvement will aid in decision-making for the operation, maintenance, and replacement
costs of the nation's aging water infrastructure; extend the service life and functionality of existing conveyance systems;
and reduce life cycle costs. This project will also show the extent of corrosion in our water infrastructure and existing
corrosion control mechanisms operating in different water distribution systems, which have prevented major lead
release episodes. These effective corrosion control mechanisms have also been vital in accomplishing disinfection and
other treatment changes in the infrastructure. Some systems, which have been thought to be effective in lower lead
through carbonate passivation, are actually reducing it through the formation of lead dioxide. This limits future
disinfection options.
OUTPUTS:
Current and future outputs of the project will consist of journal articles; conference presentations; contributions to
revisions of regulations and guidance by EPA; data reports to clients; and solutions of real-world utility infrastructure-
related water quality, corrosion, and transmission problems.
RESOURCES:
Aging Water Infrastructure Research Program: http://www.epa.gov/awi/
Corrosion, Scaling, and Metal Mobility Research: http://www.epa.gov/nrmrl/wswrd/cr/index.html
Lytle, D. A. and Schock, M. R. Pitting of Copper in High pH and Low Alkalinity Waters, Journal of the AWWA 100 (3),
2008:115-128. http://www.awwa.org/
Schock, M. R., Hyland, R. N. and Welch, M. M. Occurrence of Contaminant Accumulation in Lead Pipe Scales from
Domestic Drinking-Water Distribution Systems, Environmental Science & Technology, 42 (12), 2008:4285-4291.:
http://pubs.acs.org/
CONTACTS:
Michael Schock, Principal Investigator - (513) 569-7412 or schock.michael@epa.gov
Steven Doub, Media Relations - (513) 569-7503 ordoub.steven@epa.gov
Michelle Latham, Communications - (513) 569-7601 or latham.michelle@epa.gov
National Risk Management Research Laboratory
Water Supply and Water Resources Division
www.epa.gov/nrmrl
EPA/600/F-09/014
October 2009
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