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Microbe Concentrations, Laser Particle Counts, and Stable Hydrogen and Oxygen Isotope Ratios in Samples from a Riverbank Filtration Study, Platte River, Nebraska, 2002 to 2004

Data Series 133

By J.R. Vogel, S.I. Harris, T.B. Coplen, E.W. Rice, and I.M. Verstraeten

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Abstract

Riverbank filtration is an important process for removal of microbes, such as Cryptosporidium and Giardia , from ground waters affected by surface water. Water supplies identified as being ground water under the direct influence of surface waters are required to meet the same treatment requirements as surface water under the Surface Water Treatment Rule. Source waters that undergo riverbank filtration are after classified as ground water under the direct influence of surface water. Under many circumstances, however, environmental conditions and analytical techniques preclude direct quantification of removal of microbes of concern ( Cryptosporidium and Giardia ) during riverbank filtration. Instead, microbial and physical surrogates of these two protozoa that occur in greater concentrations and are less difficult to analyze for than Cryptosporidium and Giardia can be measured in the surface and ground waters in an attempt to quantify removal by riverbank filtration. To evaluate the use of riverbank filtration as an effective means of drinking-water treatment, a study was conducted from 2002 to 2004 by the U.S. Geological Survey, in cooperation with the City of Lincoln, at an established riverbank-filtration well field with horizontal collector wells and vertical wells. This report presents analytical methods and data collected during the study. Data are presented as generalized statistics and in figures showing temporal variations.

Sites from which water-quality samples were collected for this study included one surface-water site (Platte River), one ground-water site (W90-1H collector well), and two drinking-water sites (raw and finished). Samples from these sites were analyzed for field water-quality properties, microbe concentrations, laser particle counts, and stable hydrogen and oxygen ratios. Samples from an additional vertical well (W49-9) were analyzed for stable hydrogen and oxygen isotope ratios.

Cryptosporidium was detected in 48 percent (13 of 27) of Platte River samples collected during the study, and Giardia was detected in 44 percent (12 of 27) of Platte River samples collected during the study. Both microbes, however were not always detected in the same sample. In general, detected Cryptosporidium concentrations were greater and more variable than Giardia concentrations. Neither Cryptosporidium nor Giardia was detected in any samples from well W90-1H, the raw water, or the finished water. Aerobic spores were detected in all samples collected from the Platte River and well W90-1H during this study. The mean concentration of aerobic spores in samples from the Platte River was 2.7 magnitudes greater than the mean concentration in samples from well W90-1H. Aerobic spores were detected in 95 percent of raw water samples and in 21 percent of finished water samples. Enterococci were detected in all samples from the Platte River, in one sample from well W90-1H, in one sample from the raw water, and in no samples from the finished water. During microscopic particulate analyses (MPAs), all non-diatomaceous algae were detected less frequently and at lower average concentrations in samples from well W90-1H than in samples from the Platte River except for Phacus . At least one type of diatom was detected in all samples from the Platte River. Unclassified diatoms were detected in 2 of 14 samples from well W90-1H, in 1 of 7 raw water samples, and in none of four finished water samples. Total coliforms were detected with decreasing frequency in samples from the Platte River, well W90-1H, and raw water, respectively, and not detected in finished water samples. E. coli were detected in most of the samples collected from the Platte River and in 9 percent of the samples collected from well W90-1H. E. coli were not detected in raw or finished water samples. In the Platte River, somatic coliphages were detected more often and generally in higher levels than male-specific coliphages. Somatic and male-specific coliphages were only detected at levels near the method detection limit in a few samples from well W90-1H, the raw water, and the finished water.

In general, mean laser particle counts in each size classification decreased as size increased. Mean laser particle counts in each size classification generally were greater in samples from the Platte River than in samples from well W90-1H and also generally were greater in the raw water than in the finished water.

In surface water, stable hydrogen isotope ratios showed seasonal variations ranging from -73.1 per mill ( ‰) to -48.7 ‰ relative to Vienna Standard Mean Ocean Water reference water, and stable oxygen isotope ratios varied from -9.86 ‰ to -6.04 ‰. In ground water, stable hydrogen isotope ratios showed seasonal variations ranging from -71.6 ‰ to -45.0 ‰ relative to Vienna Standard Mean Ocean Water reference water, and stable oxygen isotope ratios varied from -9.82 ‰ to -5.25 ‰.


Contents

Abstract

Introduction

Purpose and Scope

Previous Investigations

Environmental Setting

Methods

Sampling Methods

Analytical Methods

Microbes

Cryptosporidium and Giardia

Total Coliform and E. Coli

Coliphages

Aerobic Spores

Enterococci

Microscopic Particulate Analysis

Laser Particle Counts

Stable Hydrogen and Oxygen Isotope Ratios

Quality Assurance/Quality Control

Streamflow and Well Pumpage

Field Water-Quality Properties

Microbial Concentrations

Cryptosporidium and Giardia

Total Coliform and E. coli

Coliphages

Aerobic Spores

Enterococci

Microscopic Particulate Analysis

Laser Particle Counts

Stable Hydrogen and Oxygen Isotope Ratios

References

Figures

1. Location of the riverbank filtration study at a municipal well field along the Platte River in eastern Nebraska.

2. Comparison of average daily streamflow and historical mean daily streamflow at the Platte River near Ashland gaging station (06801000).

3. Flow conditions during sampling in the Platte River near Ashland between October 2002 and September 2004.

4. Pumpage in collector well W90-1H during the period of the study.

5. Field water-quality properties at selected sites during the riverbank filtration study, Platte River, Nebraska.

6. Turbidity at selected sites during the riverbank filtration study, Platte River, Nebraska.

7. Dissolved organic carbon (DOC) in samples from the Platte River and collector well W90-1H during the riverbank filtration study, Platte River, Nebraska.

8. Stable hydrogen and oxygen isotope ratios in samples from the Platte River and the well field during the riverbank filtration study, Platte River, Nebraska.

Tables

1. Description of microbes for which samples were analyzed during riverbank filtration study, Platte River, Nebraska.

2. Field water-quality properties and dissolved organic carbon in samples collected during the riverbank filtration study, Platte River, Nebraska.

3. Percent recovery of dissolved organic carbon blind samples analyzed as part of the Organic Blind Sample Project by the National Water Quality Laboratory from February 23, 1999, to September 25, 2003.

4. Summary statistics of microbial concentrations in samples collected during riverbank filtration study, Platte River, Nebraska.

5. Cryptosporidium and Giardia concentrations in samples collected during the riverbank filtration study, Platte River, Nebraska.

6. Cryptosporidium and Giardia recovery efficiencies from analysis of samples during the riverbank filtration study, Platte River, Nebraska.

7. Total coliform, E. coli, male-specific and somatic coliphage, aerobic spore, and enterococci concentrations in samples collected during the riverbank filtration
study, Platte River, Nebraska

8. Summary statistics of microscopic particulate analysis concentrations in samples collected during riverbank filtration study, Platte River, Nebraska.

9. Microscopic particulate analysis concentrations in samples collected during the riverbank filtration study, Platte River, Nebraska.

10. Summary statistics of laser particle counts in samples collected during riverbank filtration study, Platte River, Nebraska.

11. Laser particle counts in samples collected during the riverbank filtration study, Platte River, Nebraska.

12. Stable hydrogen and oxygen isotope ratios in samples collected during the riverbank filtration study, Platte River, Nebraska.


Nebraska Water Science Center
U.S. Department of the Interior, U.S. Geological Survey
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