Current through Register Vol. 55, No. 26, June 28, 2025
(a) To establish the alternative effluent
limitations of Group B or C in §
88.292(a)
(relating to hydrologic balance: effluent standards), a permittee shall
demonstrate to the Department's satisfaction that a precipitation event has
occurred under this section.
(1) The
occurrence of a precipitation event greater than a 10-year, 24-hour
precipitation event may be demonstrated by meeting the requirements of
subsections (b)-(d) for each discharge that exceeds the effluent limits
specified in §
88.292, unless the permit
specifies a more stringent water quality based effluent limitation, in which
case no exemption will be available under this section. If the permittee
demonstrates to the Department's satisfaction that a greater than 10-year,
24-hour precipitation event has occurred, the permittee shall meet the effluent
limitation of Group C in §
88.292
(a).
(2) The occurrence of a precipitation event
equal to or less than a 10-year, 24-hour precipitation event may be
demonstrated by meeting the requirements of subsections (c) and (d) for each
discharge that exceeds the effluent limits specified in §
88.292, unless the permit
specifies a more stringent water quality based effluent limitation, in which
case no exemption will be available under this section. If the permittee
demonstrates to the Department's satisfaction that a precipitation event equal
to or less than a 10-year, 24-hour precipitation event has occurred, the
permittee shall meet the effluent limitations of Group B in §
88.292(a).
(b) The 1-year and 10-year; 24-hour
precipitation events for specific areas in this Commonwealth shall be
determined by reference to data provided by the National Oceanic and
Atmospheric Administration or equivalent resources.
(c) For the permittee to demonstrate that the
event has for the mine area been exceeded, or that dry weather flow conditions
did not exist, the permittee shall comply with one of the following:
(1) Collect 24-hour rainfall information from
official United States Weather Bureau Stations within a 25-mile
distance-radius-of the site.
(2)
Calculate the estimated rainfall event for the site, by appropriate
interpolation of the data collected under paragraph (1). Appropriate
interpolation shall be accomplished by the following:
(i) Preparing a verified copy of the chart or
readout from a Department approved flow measuring device which continuously
records the influent to the permitted treatment facility. The device shall be
approved by the Department in writing prior to the rainfall event for which the
exemption is sought and shall be secured to prevent tampering and acts of third
parties.
(ii) Preparing an analysis
identifying the runoff area tributary to the treatment facility, and compare
the actual runoff as measured and depicted by the flow measuring device with
the runoff expected from the 1-year or 10-year, 24-hour rainfall event
specified for the mine area.
(3) Develop alternative documentation or data
concerning the rainfall event. The method or system for developing the
documentation or data shall be approved in writing prior to the occurrence of
the rainfall event for which the exemption is being sought, and shall guarantee
the integrity of the information collected.
(4) Prepare an analysis identifying the
runoff area tributary to the treatment facility, and compare the actual runoff
as measured and depicted by the flow measuring device with the runoff expected
from the 1-year or 10-year, 24-hour rainfall event specified for the mine
area.
(5) Develop alternative
documentation or data concerning the rainfall event. The method or system for
developing the documentation or data shall be approved in writing prior to the
occurrence of the rainfall event for which the exemption is being sought, and
shall guarantee the integrity of the information collected.
(d) When the discharge from the
site exceeds any effluent limit in the permit, the permittee shall notify the
Department, within 5 days of the occurrence of the event, that he is applying
for an exemption from that limit and shall within 30 days thereafter provide
the following to the Department:
(1) The data
required by subsection (c).
(2) A
showing that the facility from which the discharge occurred was designed,
maintained and operated during and prior to the event to accommodate or treat a
10-year, 24-hour rainfall.
(e) The permittee is not entitled to claim a
greater than 1-year or 10-year, 24-hour precipitation event storm exemption
unless the permittee has complied with subsections (c) and (d).
(f) Nothing in this section authorizes the
Department to grant an exemption for a discharge which the Department finds may
have caused or contributed to a violation of general or specific water quality
criteria in Chapter 93 (relating to water quality
standards).
The provisions of this § 88.293 amended under
section 5 of The Clean Streams Law (35 P.S. §
691.5); sections 4(a) and 4.2 of the Surface
Mining Conservation and Reclamation Act (52 P.S.
§§
1396.4(a) and
1396.4b); section 3.2 of the
Coal Refuse Disposal Control Act (52 P.S. §
30.53b); section 7(b) of The Bituminous Mine
Subsidence and Land Conservation Act (52 P.S. §
1406.7(b)); and section
1920-A of The Administrative Code of 1929 (71 P.S. §
510-20).
This section cited in 25 Pa. Code §
88.292 (relating to hydrologic
balance: effluent standards).
