NC0086959_Staff Comments_20061205

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Michael F. Easley, Governor
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State of North Carolina
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William G. Ross, Jr., Secretary
Department of Environment and Natural Resources
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Alan W. Klimek, P.E., Director
Division of Water Quality
December 5, 2006
To: Jessica Miles, Environmental Program Manager
Public Water Supply Section, Division of Environmental Health
Through: Matt Matthews, Supervisor
Point Source Branch, Surface Water Protection Section
From: Susan A. Wilson, Supervisor
Western NPDES Program
Subject: Disposal of Wastewater Associated with Private Water Supply Wells
(with potential radiological components)
As you and your staff have stated in our previous meetings and discussions, due to EPA -
promulgated rule changes for sampling of drinking water, there is increased concern
regarding the presence of radiological components naturally occurring in the
groundwater (and subsequently in drinking water associated with the groundwater
source). Entities who operate water supply wells are now subject to more stringent
limitations prior to distribution of drinking water. In order to comply with these more
stringent limitations, further treatment of the drinking water is likely necessary. A
result of further treatment will generate wastewater via backwashing of ion exchange
units (or other treatment scenarios) which may contain radiological components (as well
as other parameters of concern) and require an NPDES permit, or modification of an
existing NPDES permit. The Division of Water Quality appreciates Public Water Supply
relaying this information, so that we can advise affected permittees on a course of action.
At this time, radiological data from the proposed wastewater sources is minimal.
However, the Division believes it has come to a consensus on how to proceed with
implementation of the radiological standards and future permitting of this wastewater
source, so that drinking water in private communities can be adequately treated and
surface water may be protected.
For most facilities, it appears that the wastewater generated from increased treatment
can be transferred to an existing wastewater treatment plant operated by the same
owner. From DWQ's perspective, this appears to be the preferred method of disposal
with the information currently available (and we encourage PWS to emphasize this
method) . However, to accept this wastewater, the affected permittee wil4need to request
and provide information for a maL modification of its existing NPDES permit. The data
would then be reviewed and submitted for public notice (as with any major modification
of an NPDES permit) . An example of the potential permit requirements for this
modification are listed in Table 1.
North Carolina Division of Water Quality [phone]
1617 Mail Service Center FAX [phone]
Raleigh, North Carolina 27699-1617 On the Internet at http://h2o.enr.state.nc.us/

The limits or monitoring requirements may vary depending on the data submitted and
the radiological components present. The list in Table 1 includes all radiological
components for which there are water quality standards or criteria. All modified permits
will also have a reopener clause to include additional parameters of concern or to
increase frequency of monitoring. As with any NPDES permit, please refer potential
applicants to the Point Source Branch so that we may answer specific questions.
At this point, DWQ will likely prohibit any application for a direct discharge to surface
waters, unless the applicant can thoroughly demonstrate that direct discharge is the
only feasible means of disposal and the limits in Table 1 can be met. In addition to the
parameters of concern listed in Table 1, the discharger may also be subject to the
monitoring required for discharges from ion exchange treatment. DWQ also prohibits
direct discharges from ion exchange treatment units into freshwater bodies, unless there
is ample dilution and the applicant can demonstrate that the limits can be met, as well
as demonstrate that there will be no adverse impact to the receiving stream. The
Division's guidance for various water treatment plant discharges can be found within the
NPDES website under Facility Specific Permitting Guidance):
http: //h2o.enr.state.nc.us /NPDES /documents.html#permittingdocs
The Division hopes the course of action outlined above will assist Public Water Supply in
decision making for existing and future drinking water supplies.
If you have any questions, please contact me at (919) 733 - 5083, ext. 510 or Toya Fields
at ext. 551.
cc: Rick Shiver, ADRO
Regional Office Supervisors/Surface Water Protection
Central Files
NPDES Programs
Planning Section/Classifications and Standards
PERCS

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Table 1. Proposed Permit Conditions
Radiological Component 1
Sampling Frequency
Limit
Combined radium-226 and
Quarterly 2
5 pCu/L
radium-228
(average annual activity)
Alpha emitters
Quarterly 2
15 pCu / L
(including radium-226, but
(average annual activity)
excluding radon and uranium
Beta emitters
Quarterly 2
50 pCu/L
(gross beta activity; excluding
(average annual activity)
potassium-40 and other naturally
occurring radionuclides
Strontium-90
Quarterly 2
8 pCu/L
(average annual activity)
Tritium
Quarterly 2
20,000 pCu/L
era a annual activity)
Uranium 3
Quarterly
30 u L(weekly average)
Footnotes:
1. Refer to 15A NCAC 2B .0200 for specific explanation of radiological components
(applicable to all surface waterbody classifications) .
2. Sampling frequency will increase to monthly should any one sample exceed four
times the average annual activity level. The permittee shall also notify the Point
Source Branch of the Surface Water Protection Section as well as the appropriate
regional office in writing, should this occur.
3. Based on EPA Federal Criteria.
Reopener Clause:
The Division of Water Quality may reopen this permit to increase monitoring, add
additional parameters of concern, and/or implement additional limits should effluent
data or surface water data indicate potential impacts, or should further information on
radiological components become available.