Current through September 17, 2024
A public water system that uses a ground water source under
the direct influence of surface water must meet all of the conditions of 179
NAC 13-004.01 and 13-004.02 and is subject to 179 NAC 13-004.03 beginning 18
months after the Director determines that it is under the direct influence of
surface water. Within 18 months of the failure of a system using a ground water
source under the direct influence of surface water to meet any one of the
requirements of 179 NAC 13-004.01 to 13-004.06 the system owner must have
installed filtration and meet the criteria for filtered systems specified in
179 NAC
13-006.
004.01 Source Water Quality Conditions
13-004.01A The fecal coliform concentration
must be equal to or less than 20 per 100 ml or the total coliform concentration
must be equal to or less than 100 per 100 ml (measured by the Department
Laboratory or an approved laboratory pursuant to 179 NAC
3-009) in representative samples of
the source water immediately prior to the first or only point of disinfection
application in at least 90% of the measurements made for the six previous
months that the system served water to the public on an ongoing basis. If a
system measures both fecal and total coliforms, the fecal coliform criterion,
but not the total coliform criterion, in this paragraph must be met.
13-004.01B The turbidity level cannot exceed
5 NTU (measured as specified in 179 NAC
13-007.01A and
13-007.02B) in
representative samples of the source water immediately prior to the first or
only point of disinfectant application unless:
1. The Director determines that any such
event was caused by circumstances that were unusual and unpredictable;
and
2. As a result of any such
event, there have not been more than two events in the past 12 months the
system served water to the public, or more than five events in the past 120
months the system served water to the public, in which the turbidity level
exceeded 5 NTU. An "event" is a series of consecutive days during which at
least one turbidity measurement each day exceeds 5 NTU.
004.02 Site-Specific Conditions
13-004.02A The public water system must meet
the requirements of 179 NAC
13-005.01A at
least 11 of the 12 previous months that the system served water to the public
on an ongoing basis, unless the system fails to meet the requirements during 2
of the 12 previous months that the system served water to the public and the
Director determines that at least one of these failures was caused by
circumstances that were unusual and unpredictable.
13-004.02B The public water system must meet
the requirements of 179 NAC
13-005.01B at all
times the system serves water to the public.
13-004.02C The public water system must meet
the requirements of 179 NAC
13-005.01C at all
times the system serves water to the public unless the Director determines that
any such failure was caused by circumstances that were unusual and
unpredictable.
13-004.02D The
public water system must meet the requirements of 179 NAC
13-005.01D on an
ongoing basis unless the Director determines that failure to meet these
requirements was not caused by a deficiency in treatment of the source
water.
13-004.02E The public water
system owner must develop and implement a wellhead protection program
sufficient to exclude potential sources of microbiological contamination within
a one year time-of-travel from the well or well field. A wellhead protection
program must consist of the following:
1.
A Wellhead Protection Area Delineation: The area
delineated must be based on a one year time-of-travel and must be determined by
use of a computer model acceptable to the Department or by the following
formula:
T =
3.14nbL2
divided by Q
Where T = Time-of-Travel (days)
L = Distance from the well (feet)
n = Effective porosity (assumed to be 0.2 unless supporting
evidence indicates otherwise) b = Aquifer thickness (feet)
Q = Pumping rate (cubic feet per day)
2. Identification of all sources of
microbiological contamination within the delineated area.
3. Management of all sources identified in
179 NAC 13-004.02E item 2 to prevent contamination from the sources.
004.03 The public water
system must be subject to an annual on-site inspection to assess the wellhead
protection program specified in 179 NAC
13-004.02E and
the disinfection treatment process. Either the Director or a party approved by
the Director must conduct the on-site inspection. The inspection must be
conducted by competent individuals such as sanitary and civil engineers,
sanitarians, or technicians who have experience and knowledge about the
operation and maintenance of a public water system, and who have a sound
understanding of public health principles and waterborne diseases. A report of
the on-site inspection must be prepared every year and indicate to the
Director's satisfaction that the disinfection treatment process is adequately
designed and maintained. The on-site inspection must include:
1. A review of the effectiveness of the
wellhead protection program required by 179 NAC
13-004.02E;
2. A review of the physical condition of the
well and the extent of protection provided;
3. A review of the system's equipment
maintenance program to ensure there is low probability for failure of the
disinfection process;
4. An
inspection of the disinfection equipment for physical deterioration;
5. A review of operating
procedures;
6. A review of data
records to ensure that all required tests are being conducted and recorded and
disinfection is effectively practiced; and
7. Identification of any improvements which
are needed in the equipment, system maintenance and operation, or data
collection.
004.04 The
public water system must not have been identified as a source of a waterborne
disease outbreak, or if it has been so identified, the system must have been
modified sufficiently to prevent another such occurrence, as determined by the
Director.
004.05 The public water
system must comply with the maximum contaminant level (MCL), for total
coliforms in 179 NAC
2-002.04C1 and
2-002.04C2 and the
MCL for E. coli in 179 NAC
2-002.04C4 at
least 11 months of the 12 previous months that the system served water to the
public, on an ongoing basis, unless the Director determines that failure to
meet this requirement was not caused by a deficiency in treatment of the source
water.
004.06 The public water
system was required to comply with the requirements for trihalomethanes in 179
NAC
2-002.04B1 and 179
NAC
3-006 until December 31, 2001. After
December 31, 2001, the system must comply with the requirements for total
trihalomethanes, haloacetic acids (five), bromate, chlorite, chlorine,
chloramines, and chlorine dioxide in 179 NAC 16.
004.07 A system that fails to meet any one of
the criteria in 179 NAC 13-004.01 and
13-004.02, and/or for which
filtration is required, and fails to install filtration is in violation of a
treatment technique requirement.
004.08 A system that has not installed
filtration is in violation of a treatment technique requirement if:
1. The turbidity level (measured as specified
in 179 NAC
13-007.01A) in a
representative sample of the source water immediately prior to the first or
only point of disinfection application exceeds 5 NTU; or
2. The system is identified as a source of a
waterborne disease outbreak.
