Arizona Water Resource Mar-Apr 2005

• Year: 2005
• Title: Arizona Water Resource
• Author: The University of Arizona Water Resources Research Center College of Agriculture and Life Sciences
• Description: March-April 2005, Volume 13, Number 5
• Publications - Doc Type: Other

March -April 2005
Arizona Water Resource
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Research Looks at Non - Treatment Options to Meet
New Arsenic Standards
EPA's lowering of the arsenic drinking water standard from 50
ppb to 10 ppb has significant consequences for Arizona. With the
old standard of 50 ppb in effect, 0.1 percent of the Arizona popu-
lation served by community water suppliers exceeded the limit.
Reducing the standard to 10 ppb results in 13 percent of the popu-
lation served exceeding the new standard, with much of this popu-
lation located in rural areas.
Treatment or non - treatment strategies are the two broad classes
of options available to Arizona water utility operators as they make
plans to meet EPA's new arsenic drinking water standard. Finding
that insufficient information is available to operators about non -
treatment strategies, University of Arizona researchers are evaluat-
ing the hydrologeologic applicability and economic cost of such
methods. The information they gather will inform decisions made
by utility operators about the best treatment or non - treatment op-
tion to use.
The researchers are especially concerned with the plight of
small water providers. Lacking extensive resources, small utilities
bear a greater burden in attempting to meet the Jan. 23, 2006 com-
pliance deadline. Their burden might be lessened if they were aware
of non - treatment strategies and able to utilize these methods rather
than rely on expensive wellhead treatment (chemical) strategies.
(The Arizona Department of Environmental Quality's Arsenic
Master Plan, developed to assist Arizona water systems, recognizes
non - treatment options but does not evaluate them. It suggests that
especially for small providers non - treatment may be preferable to
treatment options. Actual cost estimates are not provided.)
A preliminary research task is determining the feasibility of
particular methods. A review of treatment methods focuses on
basic water quality information, whereas non - treatment options
require detailed hydrogeologic characterization to define aquifer
conditions, sources of arsenic and the vertical and horizontal distri-
bution of arsenic within the aquifer.
The research project has four main objects:
(1) Select non - treatment options for evaluation. Researchers
will consult with ADEQ to select non - treatment methods best
suited for the hydrology of Arizona. The simplest non - treatment
methods include modifying pumping schedules to maximize pump-
ing from low - arsenic wells or blending water from other low- arsenic
sources. More costly methods include rehabilitating existing wells to
improve yields from low - arsenic zones, modifying existing wells to
seal off high- arsenic aquifer zones and installing properly located
and designed replacement wells.
(2) Assess the hydrogeological applicability of non - treatment
options. After selecting suitable non - treatment options the research-
ers will assess the necessary hydrogeologic conditions required for
each method. This information will be considered along with exist-
ing information about arsenic distribution and hydrogeology to de-
termine regions where non - treatment methods can be implemented.
(3) Assess cost of non - treatment options. The identified set
of non - treatment options will then be evaluated for implementa-
tion cost, with cost
estimates from con-
tractors or previous
field implementations
used. An option's cost
effectiveness will be
assessed in reference
to various character-
istics of a potential
water supplier such as
number of wells with
high- levels of arsenic
and number of house-
hold connections.
(4) Determine the
set of cost - effective
treatment or non-
treatment options.
Information generated
The University of Aritona's Department of
Hydrology and Water Resources presented it
15t' annual El Dia del Agua Student Research
Symposium on March 3. Billed `for the students"
and "by the students, " the event is an opportunity
for hydrology students to present research pr ejects.
Above is the poster session where pr elect informa-
tion was displayed. The research discussed in Spe-
cial Pr jects was included as a posterpresentation.
in (2) and (3) will be Photo: Toe Gelt
used to develop a screening tool process to enable individual water
providers to evaluate the cost effectiveness of non - treatment op-
tions compared with treatment options. By entering basic informa-
tion about their water supply (geologic /hydrologic location, number
of wells, number of households supplied, etc.), water providers will
be able to identify methods capable of achieving compliance and
evaluate their costs compared with treatment options.
If the screening shows that a non - treatment method has a
good potential to work in a particular situation, the water provider
would still need to conduct a detailed hydrogeologic investigation as
a prerequisite for implementing a non - treatment method.
Research results will be provided to ADEQ for possible incor-
poration into the state's Arsenic Master Plan; water providers will
then have access to the information along with a greater number of
options to consider.
The two -year project is in its first year. Steven Stewart and
James Hogan, both from the UA Department of Hydrology and
Water Resources, are principal investigators. Graduate student Jacob
Davis is participating in the project during its first year. For addi-
tional information contact Stewart at sstewart @hwr.arizona.edu
The research is funded by the Technology and Research Initia-
tive Fund. TRIF resulted from a November 2000 voter approved
increase in the state sales tax to support education. A portion of
the fund goes to the state's university system to invest in technology
and research -based initiatives. J%