2006 Progress Report: A Prospective Epidemiological Study of Gastrointestinal Health Effects Associated with Consumption of Conventionally Treated GroundwaterEPA Grant Number: R830376
Title: A Prospective Epidemiological Study of Gastrointestinal Health Effects Associated with Consumption of Conventionally Treated Groundwater
Investigators: Moe, Christine L. , Payment, Pierre , Rose, Joan B.
Current Investigators: Moe, Christine L. , Hooper, Stuart , Moll, Deborah , Nilsson, Kenneth
Institution: Emory University , INRS - Institut Armand-Frappier , University of South Florida
Current Institution: Emory University , Centers for Disease Control and Prevention , University of South Florida
EPA Project Officer: Page, Angela
Project Period: October 1, 2002 through September 30, 2005 (Extended to September 30, 2008)
Project Period Covered by this Report: October 1, 2005 through September 30,2006
Project Amount: $1,820,900
RFA: Microbial Risk in Drinking Water (2001) RFA Text | Recipients Lists
Research Category: Water , Drinking Water , Health Effects
The original project scope of work was modified in the summer of 2005 to focus on distribution system pressure fluctuations and microbiological water quality. It was and submitted for approval (to EPA?). Approval was received in January 2006. To fulfill the new overall goals, the project has focused on three main objectives: (1) assess distribution system pressure variability; (2) assess microbiological water quality after distribution system low pressure events, or other water quality anomalies, such as turbidity spikes or chlorine residual drops; and (3) assess microbiological water quality during and after fire hydrant flushing events. Significant progress has been made towards completion of these three objectives during the reporting period covered in this annual report.
Important Expenditures (Equipment purchases and new hires)
A water quality sensor package was purchased from Prominent. The sensor package is an important component of the automated monitoring and sampling (AMS) unit that will be used to assess microbiological water quality after distribution system low pressure events, or other water quality anomalies. It consists of several probes capable of measuring total chlorine, oxidation/reduction potential, temperature, and pH. These are low-maintenance online sensors. A compound pressure transducer, capable of measuring pressure from -15 to 185 psi will also be included, as well as an online turbidimeter, purchased from HFScientific. A datalogger was purchased from Computer Aided Solutions which will provide data acquisition, logging, and communication capabilities that are integral to the AMS. A second online turbidimeter was purchased from Hach to provide portable turbidimeter capability during fire hydrant flushing sampling. A high resolution pressure logger was also purchased (from Telog, Inc.) for use during fire hydrant flushing sampling. A pump and other equipment was purchased for use in the construction of an ultrafiltration sample concentration device.
The field work for this project is located in Hillsborough County, FL, about 460 miles south of Emory University. Therefore, two engineering students were hired to be responsible for field operations. Kenneth Nilsson is a PhD candidate at University of South Florida (USF). He received his M.S. in Environmental Engineering from University of Cincinnati and his thesis work focused on simulating accidental exposures to deliberate intrusions in pipe networks. He has experience with distribution system modeling and has participated previously in distribution system field studies. Kenneth is in charge of field operations, and is assisted by Aaron Roberts, an M.S. candidate in Environmental Engineering at USF, who has drinking water sampling experience.
Distribution System Pressure Variability
In February 2006, in cooperation with Hillsborough County Water Resource Services (HCWRS), six pressure loggers were installed at various locations throughout the distribution system: one located at the plant, three at high elevations, and two at outlying sections of the distribution system. The pressure loggers used are owned by HCWRS. Due to needs in other distribution systems operated by HCWRS, during various time periods loggers have been removed from service to this study and used elsewhere to fulfill their needs. In some cases, HCWRS will share these data with the study. At times there have been as few as two loggers collecting data in the HCSC distribution system. Overall, we have collected ________ days of pressure data, spread throughout six distribution system locations. A total of ______ low pressure events have been observed (<20 psi), and during ________ of these events the logger recorded a pressure below 1 psi, indicating the likelihood that a negative pressure event may have occurred, as the minimum pressure reading these loggers are capable of is 0 psi. _______ events were system-wide events, affecting all loggers in service, while ____ events were isolated to one logger, indicating a localized low pressure event. Figures 1 and 2 are examples of the pressure fluctuations during two events detected.
Baseline Microbiological Water Quality Sampling
Microbiological water quality sampling at the plant source and at the point-of-entry (POE) to the distribution system was conducted to establish a baseline of water quality entering and leaving the treatment plant. Prior to sampling, an ultrafiltration sample concentration device was constructed for use by Florida Department of Health – Bureau of Laboratories, Tampa (FDH), based on methods developed by Vincent Hill at CDC. By concentrating large volume samples, the detection limit for bacteria and viruses analyzed can be increased significantly. In this study, we are collecting 100-L composite samples, and they are being concentrated through ultrafiltration to a final volume of 2 L. Therefore, the theoretical increase in detection limit is by about a factor of 50.
In March, the project engineer installed the system at FDH and trained their personnel on its use. The lab conducted various seeding and recovery experiments using the equipment over the next several weeks. Source and POE sampling began on May 23, and has continued about weekly to the time this report was submitted. We expect to continue with plant source and POE sampling weekly as long as funding and lab capacity allows. (Source water sampling, but not POE sampling, has been dropped on weeks that hydrant flushing events are performed, due to the number of samples generated during the flushing events.)
Table X summarizes the results of source and POE microbiological sampling to date for bacteria. As of the time of this writing, laboratory results for samples collected between May 23 and August 29, 2006. All samples for coliphage, both somatic and MS2 have been negative (11 paired grab and composite source water samples, 15 paired grab and composite POE samples).
Two total coliform samples were positive. Both of these corresponded to the POE composite sample: 32 and 1 cfu/L on May 23 and June 20, respectively. Several samples in both the source and POE were positive for A. hydrophila, as summarized in Figure Z.
The data collected during weekly source and POE sampling serves three important purposes: (1) it provides a baseline level of microbiological water quality entering the distribution system to which distribution samples collected can be compared, (2) it provides a comparison of the impact of treatment on microbiological water quality at this plant, and (3) it provides an opportunity to evaluate the effectiveness of 2-L grab sampling as compared to 100-L composite sampling for assessing water quality.
Figure Z Summary of positive A.hydrophila samples Alternate:
NS: Not sampled
BDL: Below detection limit (0.2 cfu/L for composite samples, 4 cfu/L for grab samples)
Table Y summarizes the results for heterotrophic plate count (HPC).
Impact of Fire Hydrant Flushing on Distribution System Water Quality
Line maintenance personnel routinely flush hydrants in certain areas of the HCSC distribution system to maintain water quality. Typically, areas that are know to require hydrant flushing to maintain adequate disinfectant levels are flushed regularly, from a frequency of once per week to once per month. In some cases, hydrants are outfitted with an automated low-flow flushing apparatus that allows for daily flushing. Based on this information, project personnel requested and received permission from HCWRS to monitor and sample water during up to 12 flushing events. HCWRS has committed personnel to facilitate this field work. As of this writing, two flushing events have been monitored and sampled, although the data is not yet ready to be summarized here. The overall objective for this phase of the project will be to monitor and sample before, during, and after flushing events located at hydrants that fall into three flushing frequency categories: frequently (about once per week), infrequently (once per month), and areas that are not know to have been flushed in recent history.
Beginning the day before the flushing event, the hydrant is opened to a low flow rate allowing turbidity to be continuously monitored from one sidearm, while pressure is monitored on the other sidearm using a high resolution pressure logger. These monitors are also in place during the flushing event. An online turbidimeter was customized to operate on battery power and installed inside a watertight enclosure to provide portable continuous turbidity monitoring capability. Baseline composite and grab samples are collected the day before flushing. A composite sample and three grab samples are collected during the flush, and a last pair of composite and grab samples are collected 30 minutes to two hours after the flushing event.
Design, Construction, and Testing of an Water Quality Automated Monitoring and Sampling (AMS) Unit
Progress has been made on the design and construction of the water quality automated monitoring and sampling (AMS) unit. All water quality sensors have been purchased and received (total chlorine, pH, temperature, conductivity, oxidation/reduction potential); a datalogger has been identified for use, ordered, and received; a -15 to 185 psi compound pressure transducer has been identified, ordered, and received; all solenoid valves to be used for sampling, as well as parts for a custom-designed stainless steel sampling manifold have been ordered and received. The power supply system (consisting of a 24VDC power supply, back up sealed lead acid batteries, and battery backup module) has been designed, and all components have been ordered and received. The only major component that has not been received at the time of this writing is the online turbidimeter for use by the AMS. However, this component has been purchased and delivery is expected in October.
The AMS is currently being constructed and tested in the laboratory. Figure Z below details the design of the AMS.
We plan on reviewing the physical and microbiological water quality results from the first 2-3 flushing events to make any necessary changes to the experimental protocol. The overall goal is to sample during about 12 flushing events, distributed evenly between areas that are frequently, infrequently, and never flushed. We also will try to collect samples at flushing events located in industrial and residential areas.
Baseline water quality sampling of the plant source water and at the POE will continue throughout the project, as long as time and funding permits, on a weekly basis. The frequency of sampling may decrease due to funding limitations.
Once the AMS is completed it will be tested and then installed in the field. Baseline samples at the POE and in the distribution system, not related to pressure or water quality anomalies, will be collected at random times, in addition to any samples collected due to pressure drops or water quality anomalies.
Journal Articles on this Report : 1 Displayed | Download in RIS Format
|Other project views:||All 12 publications||1 publications in selected types||All 1 journal articles|
||Tinker SC, Moe CL, Klein M, Flanders WD, Uber J, Amirtharajah A, Singer P, Tolbert PE. Drinking water turbidity and emergency department visits for gastrointestinal illness in Atlanta, 1993-2004. Journal of Exposure Science & Environmental Epidemiology 2010;20(1):19-28.||