Description:
This experiment is a field test of bank filtration at a site where water level and salinity vary on an annual basis, as they do in many arid and semi-arid streams. No other studies of bank filtration have been performed in this kind of setting. Along the border with Mexico, shallow wells in the Rio Grande alluvium provide untreated water to the residents of many communities. Knowledge about the effectiveness of bank filtration can help prevent disease and provide affordable water supplies for residents of both countries. Additionally, the large cities along the Rio Grande are rapidly drawing down their aquifers and are planning on using Rio Grande water as their primary supplies. Although most cities are planning to use treatment facilities to supply municipal water, bank filtration may provide a cost-effective pretreatment method.
Bank filtration is the cleaning of contaminated water by pumping it from a
stream through the banks to a well. The objective of this study is to determine
whether bank filtration is effective at removing particulates and microbial
pathogens in the Rio Grande, an arid stream that exhibits significant annual
fluctuations in water quantity and chemistry. This experiment will test bank
filtration at a site where water level and salinity vary on an annual basis, as
they do in many arid and semi-arid streams. No other studies of bank filtration
have been performed in this kind of setting.
Waters of different chemistries mix during bank filtration, resulting in
complex interactions between soil, bacteria, pollutants and dissolved solids.
During bank filtration, organic solids in the river water are strained out into
alluvial sediments (Brand et al., 1989; Schwarzenbach and Westall, 1981).
Microbial reduction of these organics often creates an anaerobic zone, a few
meters wide, in which heavy metals are mobilized. Beyond the anaerobic zone, the
subsurface alluvial environment becomes aerobic. In the aerobic zone, trace
elements and heavy metals are immobilized and organic pollutants are reduced to
harmless compounds.
In humid climates, bank filtration has been shown to remove the majority of
dissolved organic constituents and heavy metals [e.g. (Sontheimer, 1980)].
Although bank filtration has been successful in humid climates (Hoetzl et al.,
1989; Laszlo and Szekely, 1989), there is little data from arid climates.
Bank storage/filtration technology is more difficult to apply to the Rio Grande
because of (1) the arid climate, (2) heterogeneous sand-dominated river
deposits, and (3) possible long-term salt or arsenic accumulation in the
sediments.
The overall objective of this research proposal is to determine whether bank
filtration is effective at removing particulates and microbial pathogens. The
experiments are designed to address the following questions:
1. Is the stream the source of the water? Do stratigraphic heterogeneities
reduce the effectiveness of bank filtration?
2. Does variation in salinity and water depth change the effectiveness of
bank filtration?
3. Does pumping rate change the effectiveness of bank filtration?
Related Organizations:
Role: OWNER
Organization Name: TEXAS A & M UNIVERSITY
Citation: College Station
State: TX
Zip Code: 77843
Role: OWNER
Organization Name: UNIVERSITY OF TEXAS AT EL PASO
Mailing Address: 500 W University Ave
Citation: El Paso
State: TX
Zip Code: 79968
Project Information:
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: Drinking Water
Risk Paradigm: EXPOSURE
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: ARSENIC
Risk Paradigm: EXPOSURE
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: M/DBP (MICROBIAL)
Risk Paradigm: EXPOSURE
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: ARSENIC
Risk Paradigm: RISK ASSESSMENT
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: Drinking Water
Risk Paradigm: RISK MANAGEMENT
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: M/DBP (MICROBIAL)
Risk Paradigm: RISK MANAGEMENT
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: ARSENIC
Risk Paradigm: RISK MANAGEMENT
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: M/DBP (MICROBIAL)
Risk Paradigm: RISK ASSESSMENT
Approach: The experiment will be a field experiment conducted at a research site
established by the University of Texas at El Paso. The bank-filtration research
site offers important advantages as the researchers can manipulate well spacing
and pumping rates to best fit the design of the experiment. For this experiment,
a very short riverbank to pumping well distance is used to minimize dilution of
pathogen species.
Wells will be drilled in a cross pattern at the experiment site. Wells along
the axis of the cross will document decreases in pathogen, while wells along the
cross-bar will document dispersion of the flow between the river and the pumping
well. We will characterize the experiment site by detailed analysis of cores
collected from the wells. Slugs of Bromide from three injection wells will be
used to document the flow paths between the stream and the pumping wells.
Multi-level wells will be used to document vertical heterogeneities in flow.
Water samples will be collected twice each month during each of the three
years of the project. Samples will be collected as soon as flooding begins, and
then at two-week intervals during the November to February flooding of the
channel. Water samples will be collected twice a month and analyzed for water
chemistry. Samples will be analyzed monthly for Giardia,
Cryptosporidium, and E. coli. A three dimensional
model of water flow between the stream and the well will be created and the
effectiveness of bank filtration will be measured.
Repeated sampling will document the effects of changes in water chemistry and each year the site will be sampled using a different pumping rate for the
experiment well.
Cost: $437,418.00
Status: Ongoing. See Download section for progress reports.
Research Component: Drinking Water
Risk Paradigm: RISK ASSESSMENT
Project IDs:
ID Code: R829009
Project type: EPA Grant