Attachment 179-13-2 - Protocol for the Determination of Influence of Surface Water on Ground Water SourcesI.Background: The Surface Water Treatment Rule (SWTR) promulgated by EPA requires that treatment sufficient to produce a three-log ( 99.9%) reduction in Giardia lamblia cysts and a four-log ( 99.99%) reduction in viruses be provided for all surface water sources and all ground water sources under the direct influence of surface water. The basic criteria which determines direct influence of surface water on ground water sources, within the context of the SWTR, is the possibility of Giardia cysts being carried into the ground water by infiltrating surface water. The more recent Interim Enhanced Surface Water Treatment Rule (IESWTR) and Long Term 1 Enhanced Surface Water Treatment Rule (LT1) add the requirement for 2-log (99%) removal of Cryptosporidium oocysts for all surface water sources and all ground water sources under the direct influence of surface water.II.Obvious Surface Water Sources: The Department has identified ponds, lakes, and streams as obvious sources of surface water.III.Protocol for Ground Water Under the Direct Influence of Surface Water Determination: The definitive determination of the influence of surface water is to perform particulate analyses on water samples collected from public water sources. A.New Sources: The following screening protocol will identify the sources for which particulate analysis will be necessary. Department personnel will examine information on file to determine if a source of water is potentially at risk to the direct influence of surface water. If any one of the following conditions is true, then the source of water is potentially at risk to the direct influence of surface water: 1. The source of water is a spring, horizontal/radial collector well, or an infiltration gallery;2. The top of the uppermost intake structure of a well is less than or equal to 50 feet from the ground surface;3. There is evidence of E. coli contamination of the discharge of the source;4. The source of water is less than 200 feet from a source of surface water or the sloping margin of, or the ground bordering a stream that serves to confine the water to the natural channel during the normal course of flow. It is best marked where a distinct channel has been eroded in the valley floor, or where there is a cessation of land vegetation.5. There are defects in the condition of the upper terminus (e.g., defective well seals, grouting, or other defects in the upper annulus);6. There is inadequate information on file to assess whether the source of water meets one or more of the conditions in III.A.1 through III.A.4. In this case, owners of the public water system will be given the opportunity to provide the required information.B.Existing Sources: Any existing source will be evaluated under the screening protocol for new sources if any one of the following conditions exists: 1. A waterborne disease outbreak takes place in the public water system service area and the public water system is suspected of being the cause;2. There is evidence of E. coli contamination in the source water and the source water meets any of the criteria in III.A above; or3. The public water system has continuous disinfection, the source water meets any of the criteria in III.A above, and the source has not been previously evaluated by the Department using temperature, pH, turbidity, or microscopic particulate analysis.C.Not Under the Direct Influence: A source of water that does not meet any of the criteria in III.A or III.B above is not considered to be at risk to the direct influence of surface water and Title 179 regulations regarding surface water and ground water under the direct influence of surface water do not apply.D.At Risk: If a source of water is determined to be potentially at risk to the direct influence of surface water in accordance with the criteria in III.A or III.B above, particulate analysis samples must be taken from the source as follows: 1. A minimum of a set of two samples must be collected and analyses performed for the presence of green algae, blue-green algae, diatoms, nematodes, flagellates, and gastrotrichs. The second sample must be taken a minimum of 24 hours after the conclusion of the previous sampling. Samples must be collected in accordance with the Consensus Method for Determining Groundwaters under the Direct Influence of Surface Water Using Microscopic Particulate Analysis (MPA) which is incorporated herein by reference. This publication is available from the National Technical Information Service, NTIS PB 93-180818, U.S. Department of Commerce, 5301 Shawnee Road, Alexandria, Virginia 22161. The toll-free number is 800-553-6847. This document may be inspected at the Division of Public Health of the Department of Health and Human Services, 301 Centennial Mall South, Lincoln, NE 68509. Sample collection must be at such times as the ground water source is most vulnerable to surface water infiltration (e.g., during periods of high surface water stages, after heavy rainfall or runoff events); however, sample collection will not be required when the source would not be used due to abnormal conditions including but not limited to flooding and natural disasters. Sample volumes must be at least 500 gallons. Analysis must be made by a certified laboratory that has entered into an agreement with the Department laboratory as specified in 179 NAC 20.2. The presence of any of the indicators given in III.D.1 in both samples will be considered conclusive evidence of surface water influence and the source is subject to Title 179 regulations regarding surface water and ground water under the direct influence of surface water unless the system is able to determine that a structural defect led to the presence of indicator organisms in the sample(s). If a structural defect is found and corrected, the system may sample again in order to determine if the source is under the direct influence of surface water.
3. If sample results are inconsistent, an additional set of two samples must be taken as directed by the Department. If any two of the four samples taken contain any of the indicators listed in III.D.1, their presence will be considered conclusive evidence of surface water influence and the source is subject to Title 179 regulations regarding surface water and ground water under the direct influence of surface water.179 Neb. Admin. Code, ch. 13, Attachment 2
Amended effective 3/22/2016.