2002 Progress Report: Riverbank Filtration Effectiveness in an Arid Environment

EPA Grant Number: R829009
Title: Riverbank Filtration Effectiveness in an Arid Environment
Investigators: Langford, Richard P. , Pillai, Surresh , Schulze-Makuch, Dirk
Institution: The University of Texas at Austin , Texas A & M University
Current Institution: The University of Texas at El Paso , Texas A & M University
EPA Project Officer: Page, Angela
Project Period: September 1, 2001 through August 31, 2004 (Extended to August 28, 2005)
Project Period Covered by this Report: September 1, 2001 through August 31, 2002
Project Amount: $437,418
RFA: Drinking Water (2000) RFA Text |  Recipients Lists
Research Category: Drinking Water , Water

Objective:

The objective of this research project is to determine whether bank filtration in an arid environment is effective at removing particulates and microbial pathogens. The field site for the proposed studies is unique in that it is located in an arid region and utilizes the Rio Grande River system that exhibits significant fluctuations in both water quantity and quality. The results from these studies can be significant for this region because the region relies almost exclusively on aquifers for its municipal drinking water.

Progress Summary:

The program is on schedule, given the delay in funding that did not allow completion of the well field before the channel went dry in February. The sediment analysis and well tests have been extremely favorable, and the initial sampling for water chemistry and biological sampling are providing results that are explained by the sediment heterogeneities. This fall, as water is just being allowed into the channel, we expect to make rapid progress.

Task 1: Site Construction. This task is complete. The site is now more densely drilled than in the proposal. The well array, consisting of multiply screened wells, was constructed and is ready for experimental testing. The pump has been installed and tested.

Task 2: Characterization of Sediment and Flow Between Stream Bank and Well. Characterization of the sediment is complete and is described on the project Web site. Characterization of the aquifer is progressing. The analysis following the aquifer test revealed transmissivity and storage values of the shallow aquifer and helped quantify hydrological heterogeneities in the subsurface of the experimental site. Background water samples were taken from the pumping well, selected monitoring well, and the Rio Grande drainage channel, and analyzed for major cations and anions, bacterial nutritional parameters (e.g., total phosphorus, water Kjeldahl nitrogen), pesticides, and polychlorinated biphenyls (PCBs). Further, biological pathogens were quantified from these sampling locations as well. The tests revealed a heterogeneous distribution of the bacteria and phages. Currently, we are preparing the first tracer test with bromide as tracer and after that we will use microspheres as tracers to better understand the aquifers' characteristics in regard to chemical and bacterial subsurface transport.

Task 3: Sample Collection and Analysis. Background water samples were taken from the pumping well, selected monitoring well, and the Rio Grande drainage channel, and analyzed for major cations and anions, bacterial nutritional parameters (e.g., total phosphorus, water Kjeldahl nitrogen), pesticides, and PCBs. Further, biological pathogens were quantified from these sampling locations as well. The tests revealed a heterogeneous distribution of bacteria and phages.

Intensive microbial sampling will be initiated in the last week of September for Escherichia coli, male specific coliphages, somatic coliphages, enterococci, Salmonella, enteric viruses, and Cryptosporidium. These samples will be collected from the canal on a monthly basis. Additionally, samples will be analyzed twice per week for up to 4 weeks (from the canal) for E. coli and somatic coliphages to better understand the occurrence and levels of these indicator organisms.

Task 4: Analysis and Interpretation of Results. Analysis of sediment data is complete. Analysis of water and bacteria analysis has begun for the background samples but not for the experimental tracer tests. Initial bacterial samples highlight the importance of the heterogeneities in the sediments. The highest values recorded were adjacent to the pumping well and farthest from the stream channel. These initial results seem to indicate that the bacterial samples are confined to the upper 1 m of the aquifer by heterogeneities.

Future Activities:

Future activities include intensive microbial sampling that will be initiated in the last week of September for E. coli, male specific coliphages, somatic coliphages, enterococci, Salmonella, enteric viruses, and Cryptosporidium. These samples will be collected from the canal on a monthly basis. Additionally, samples will be analyzed twice per week for up to 4 weeks (from the canal) for E. coli and somatic coliphages to better understand the occurrence and levels of these indicator organisms.

Journal Articles:

No journal articles submitted with this report: View all 10 publications for this project

Supplemental Keywords:

coliphages, enterococci, E. coli, Cryptosporidium, water chemistry, sediment heterogeneity, arid soil, bank filtration, bacterial transport, subsurface., RFA, Health, Scientific Discipline, Geographic Area, Waste, Water, Contaminated Sediments, Environmental Chemistry, Health Risk Assessment, Arsenic, Risk Assessments, Biochemistry, Environmental Monitoring, Ecological Risk Assessment, Drinking Water, Groundwater remediation, EPA Region, monitoring, pathogens, fate and transport, risk assessment, contaminant transport, exposure and effects, natural disinfection, contaminated sediment, exposure, chemical contaminants, E. Coli, Region 6, cryptosporidium , treatment, municipal water, microbial risk management, human exposure, arsenic mobility, water quality, groundwater contamination, drinking water contaminants, drinking water treatment, Giardia, water treatment, arsenic exposure, riverbank filtration, groundwater

Progress and Final Reports:

Original Abstract
  • 2003 Progress Report
  • 2004 Progress Report
  • Final Report