Current through Register Vol. 39, No. 6, September 16, 2024
The following is the management strategy for new and
expanding wastewater dischargers in the Tar-Pamlico River basin:
(1) Purpose. The purpose of this Rule is to
establish minimum nutrient control requirements for new and expanding point
source discharges in the Tar-Pamlico River Basin in order to maintain or
restore water quality in the Pamlico Estuary and protect its designated
uses.
(2) Applicability. This Rule
applies to all discharges from wastewater treatment facilities in the
Tar-Pamlico River Basin that receive nitrogen- or phosphorus-bearing wastewater
and are required to obtain individual NPDES permits. This Rule applies to
Tar-Pamlico Basin Association member facilities on or after June 1, 2025. This
Rule applies to other facilities upon this Rule's effective date.
(3) Definitions. The terms used in this Rule,
in regard to point source dischargers, treatment facilities, wastewater flows
or discharges, or like matters, shall be as defined in Rule .0701 of this
Section and as follows:
(a) "Existing" means
that which obtained an NPDES permit on or before December 8, 1994.
(b) "Expanding" means that which increases
beyond its permitted flow as defined in Item (4) of this Rule.
(c) "New" means that which had not obtained
an NPDES permit on or before December 8, 1994.
(4) "Permitted flow" means the maximum
monthly average flow authorized in a facility's NPDES permit as of December 8,
1994.
(5) This Item specifies
nutrient controls for new facilities.
(a)
Proposed new wastewater dischargers shall evaluate all practical alternatives
to surface water discharge pursuant to
15A NCAC
02H .0105(c)(2) prior to
submitting an application to discharge.
(b) The technology-based nitrogen and
phosphorus discharge limits for a new facility shall not exceed:
(i) For facilities treating municipal or
domestic wastewater, the mass load equivalent to a concentration of 3.5 mg/L TN
and 0.5 mg/L TP at the monthly average flow limit in the facility's NPDES
permit; and
(ii) For facilities
treating industrial wastewater, the mass load equivalent to the best available
technology economically achievable, calculated at the monthly average flow
limit in the facility's NPDES permit.
(c) Proposed new dischargers submitting an
application shall acquire nutrient allocation from existing dischargers or
nutrient offset credits pursuant to Rule .0703 of this Section for the mass
load dictated by this Item. The allocation and offset credits shall be
sufficient for any partial calendar year in which the permit becomes effective
plus 10 subsequent years of discharge at the proposed design flow rate in
accordance with
15A NCAC
02H .0112(c).
(d) The Director shall not issue a permit
authorizing discharge from a new facility unless the applicant has satisfied
the requirements of Sub-Items (a), (c), and (e) of this Item. If a facility's
permit contains tiered flow limits for expansion, the Director shall not
authorize an increased discharge unless the applicant has satisfied the
requirements of Sub-Items (a), (c), and (e) of this Item.
(e) Subsequent applications for permit
renewal shall demonstrate that the facility has sufficient nitrogen allocation
or offset credits to meet its effluent nutrient limitations for any partial
calendar year in which the permit becomes effective plus 10 subsequent years of
discharge at the proposed design flow rate in accordance with
15A NCAC
02H .0112(c).
(f) The Director shall establish more
stringent limits for nitrogen or phosphorus upon finding that such limits are
necessary to protect water quality standards in localized areas.
(6) This Item specifies nutrient
controls for expanding facilities.
(a)
Expanding facilities shall evaluate all practical alternatives to surface water
discharge pursuant to
15A NCAC
02H .0105(c)(2) prior to
submitting an application to discharge.
(b) The nitrogen and phosphorus discharge
limits for an expanding facility shall not exceed the greater of loads
equivalent to its active allocation and offset credit, or the following
technology-based mass limits:
(i) For
facilities treating municipal or domestic wastewater, the mass equivalent to a
concentration of 3.5 mg/L TN and 0.5 mg/L TP at the monthly average flow limit
in the NPDES permit; and
(ii) For
facilities treating industrial wastewater, the mass load equivalent to the best
available technology economically achievable, calculated at the monthly average
flow limit in the facility's NPDES permit.
(c) Facilities submitting application for
increased discharge or, where an existing permit contains tiered flow limits,
for authorization to discharge at an increased flow, shall acquire or
demonstrate contractual agreement to acquire, prior to authorization to
discharge at the increased flow, nutrient allocation from existing dischargers
or nutrient offset credits pursuant to Rule .0703 of this Section for the
proposed discharge above 0.5 million gallons per day (MGD). The allocation and
offset credits shall be sufficient to meet its effluent nutrient limitations
for any partial calendar year in which the permit becomes effective plus 10
subsequent years of discharge at the proposed design flow rate in accordance
with 15A
NCAC 02H .0112(c).
(d) The Director shall not issue a permit
authorizing increased discharge from an existing facility unless the applicant
has satisfied the requirements of Sub-Items (a), (c), and (e) of this Item. If
a facility's permit contains tiered flow limits for expansion, the Director
shall not authorize discharge at an increased flow unless the applicant has
satisfied the requirements of Sub-Items (a), (c), and (e) of this
Item.
(e) Subsequent applications
for permit renewal shall demonstrate that the facility has sufficient nitrogen
allocation or offset credits to meet its effluent nutrient limitations for any
partial calendar year in which the permit becomes effective plus 10 subsequent
years of discharge at the proposed design flow rate in accordance with
15A NCAC
02H .0112(c).
(f) The Director shall modify an expanding
facility's permit to establish more stringent limits for nitrogen or phosphorus
upon finding that such limits are necessary to protect water quality standards
in localized areas.
(g) Existing
wastewater dischargers expanding to greater than 0.5 MGD design capacity may
petition the Director for an exemption from Sub-Items (a) through (c) and (e)
of this Item upon meeting and maintaining all of the following conditions:
(i) The facility has reduced its annual
average TN and TP loading by 30 percent from its annual average 1991 TN and TP
loading. Industrial facilities may alternatively demonstrate that nitrogen and
phosphorus are not part of the waste stream above background levels.
(ii) The expansion does not result in annual
average TN or TP loading greater than 70 percent of the 1991 annual average TN
or TP load. Permit limits shall be established to ensure that the 70 percent
load is not exceeded.
Authority
G.S.
143-214.1;
143-215.1;
143-215.3(a)(1);
143-215.8B;
143B-282;
Eff. April
1, 1997;
Recodified from
15A NCAC
02B .0229 Eff. April 1, 2020;
Readopted Eff. April 1, 2020.
