Current through Register Vol. 54, No. 44, November 2, 2024
Each method of release detection for tanks used to
meet the requirements in §§
245.441 and
245.442 (relating to general
requirements for underground storage tank systems; and periodic monitoring
requirements for petroleum underground storage tank systems) shall be conducted
in accordance with all of the following:
(1)
Manual tank gauging.
Manual tank gauging shall meet the following requirements:
(i) Tank liquid level measurements are taken
at the beginning and ending of a period of at least 36 hours during which no
liquid is added to or removed from the tank.
(ii) Level measurements are based on an
average of two consecutive stick readings at both the beginning and ending of
the period.
(iii) The equipment
used is capable of measuring the level of product over the full range of the
tank's height to the nearest 1/8 of an inch.
(iv) A leak is suspected and subject to
Subchapter D (relating to corrective action process for owners and operators of
storage tanks and storage tank facilities and other responsible parties) if the
variation between beginning and ending measurements exceeds the weekly or
monthly standards in the following table:
| Nominal Tank
Capacity | Minimum Duration of
Test | Weekly Standard (one
test) | Monthly Standard (average of) four
tests | Periodic Tightness Test Required |
| 550 gallons or less | 36 hours
| 10 gallons | 5 gallons | No |
| 551-1,000 gallons: 64" diameter tank
| 44 hours | 9 gallons | 4 gallons | No |
| 551-1,000 gallons: 48" diameter tank
| 58 hours | 12 gallons | 6 gallons | No |
| 551-1,000 gallons | 36 hours
| 13 gallons | 7 gallons | Yes |
(v) Owners and operators of underground
storage tanks of greater than 1,000 gallons nominal capacity may not use this
method to meet the requirements in this section.
(2)
Tank tightness testing.
Tank tightness testing, or another test of equivalent performance, must be
capable of detecting a 0.1 gallon per hour leak rate from any portion of the
tank that routinely contains product while accounting for the effects of
thermal expansion or contraction of the product, vapor pockets, tank
deformation, evaporation or condensation, and the location of the water
table.
(3)
Automatic tank
gauging. Equipment for automatic tank gauging that tests for the loss
of product and conducts inventory control must meet one of the following
requirements:
(i) The automatic product level
monitor test can detect a 0.2 gallon per hour leak rate from any portion of the
tank that routinely contains product.
(ii) Tank gauges shall be certified by an
independent third-party verifying the gauge's ability to detect the leak rate
in subparagraph (i) following EPA evaluation protocol.
(4)
Vapor monitoring.
Testing or monitoring for vapors within the soil gas of the excavation zone
must meet the following requirements:
(i) The
materials used as backfill are sufficiently porous-for example, gravel, sand or
crushed rock-to readily allow diffusion of vapors from releases into the
excavation area.
(ii) The stored
regulated substance, or a tracer compound placed in the tank system, is
sufficiently volatile for example, gasoline-to result in a vapor level that is
detectable by the monitoring devices located in the excavation zone in the
event of a release from the tank.
(iii) The measurement of vapors by the
monitoring device is not rendered inoperative by the groundwater, rainfall or
soil moisture or other known interferences so that a release could go
undetected for more than 30 days.
(iv) The level of background contamination in
the excavation zone will not interfere with the method used to detect releases
from the tank.
(v) The vapor
monitors are designed and operated to detect any significant increase in
concentration above background of the regulated substance stored in the tank
system, a component of that substance or a tracer compound placed in the tank
system.
(vi) In the underground
storage tank excavation zone, the site is evaluated by a licensed professional
under the Engineer, Land Surveyor and Geologist Law (63 P. S. §§ 148-158.2) to ensure compliance with
subparagraphs (i)-(iv) and to establish the number and positioning of
monitoring wells that will detect releases within the excavation zone from any
portion of the tank that routinely contains product. The written site
evaluation report authenticated by the person completing the evaluation must be
maintained at the facility for the duration of the leak detection
method.
(5)
Groundwater monitoring. Testing or monitoring for liquids on
the groundwater must meet the following requirements:
(i) The regulated substance stored is
immiscible in water and has a specific gravity of less than one.
(ii) Groundwater is never more than 20 feet
from the ground surface and the hydraulic conductivity of the soils between the
underground storage tank system and the monitoring wells or devices is not less
than 0.01 cm/sec-for example, the soil should consist of gravels, coarse to
medium sands, coarse silts or other permeable materials.
(iii) The slotted portion of the monitoring
well casing shall be designed to prevent migration of natural soils or filter
pack into the well and to allow entry of regulated substances on the water
table into the well under both high and low groundwater conditions.
(iv) Monitoring wells shall be sealed from
the ground surface to the top of the filter pack.
(v) Monitoring wells or devices intercept the
excavation zone or are as close to it as is technically feasible.
(vi) The continuous monitoring devices or
manual methods used can detect the presence of at least 1/8 of an inch of free
product on top of the groundwater in the monitoring wells.
(vii) Within and immediately below the
underground storage tank system excavation zone, the site is evaluated by a
licensed professional under the Engineer, Land Surveyor and Geologist Law to
ensure compliance with subparagraphs (i)-(v) and to establish the number and
positioning of monitoring wells or devices that will detect releases from any
portion of the tank that routinely contains product. The written site
evaluation report authenticated by the person completing the evaluation must be
maintained at the facility for the duration of the leak detection
method.
(viii) Monitoring wells are
clearly marked and secured to avoid unauthorized access and tampering in
accordance with § 245.432(b).
(6)
Interstitial monitoring.
Interstitial monitoring between the underground storage tank system and a
secondary barrier immediately around or beneath it may be used, but only if the
system is designed, constructed and installed to detect a leak from any portion
of the tank that routinely contains product and also meets one of the following
requirements:
(i) For double-walled
underground storage tank systems, the sampling or testing method can detect a
release through the inner wall in any portion of the tank that routinely
contains product.
(ii) For
underground storage tank systems with a secondary barrier within the excavation
zone, the sampling or testing method used can detect a release between the
underground storage tank system and the secondary barrier.
(A) The secondary barrier around or beneath
the underground storage tank system consists of artificially constructed
material that is sufficiently thick and impermeable, at least
10-6 cm/sec for the regulated substance stored, to
direct a release to the monitoring point and permit its detection.
(B) The barrier is compatible with the
regulated substance stored so that a release from the underground storage tank
system will not cause a deterioration of the barrier allowing a release to pass
through undetected.
(C) For
cathodically protected tanks, the secondary barrier shall be installed so that
it does not interfere with the proper operation of the cathodic protection
system.
(D) The groundwater, soil
moisture or rainfall will not render the testing or sampling method used
inoperative so that a release could go undetected for more than 30
days.
(E) The site is assessed to
ensure that the secondary barrier is always above the groundwater and not in a
25-year floodplain, unless the barrier and monitoring designs are for use under
these conditions.
(F) Monitoring
wells are clearly marked and secured to avoid unauthorized access and tampering
in accordance with § 245.432(b).
(iii) For tanks with an internally fitted
liner, an automated device can detect a release between the inner wall of the
tank and the liner, and the liner is compatible with the substance
stored.
(7)
Statistical Inventory Reconciliation (SIR). SIR shall meet the
performance standards of paragraph (8)(i) for monthly monitoring.
(i) The owner or operator shall follow the
instructions of the SIR manufacturer's protocol.
(ii) A separate report for each tank
monitored shall be maintained by the owner or operator in accordance with
§
245.446(2)
(relating to release detection recordkeeping). Each report shall meet the
following requirements:
(A) A valid report
shall include the calculated leak rate, positive for out of tank and negative
for into tank, minimum detectable leak rate (MDL), leak detection threshold,
probability of detection (Pd) and probability of false alarm (Pfa) which the
supplied data supports.
(B) A valid
report shall also include one of the following test results:
(I) If the calculated leak rate, absolute
value, is less than the leak threshold and the MDL is less than or equal to the
certified performance standard, the test result is "pass."
(II) If the calculated leak rate, absolute
value, is greater than the leak threshold, the test result is "fail."
(III) If the MDL exceeds the certified
performance standard and the calculated leak rate is less than the leak
threshold, the test result is "inconclusive." An inconclusive result is
considered a suspected leak and shall be investigated in accordance with §
245.304 (relating to investigation
and reporting of suspected releases).
(8)
Other methods. Other
types of release detection methods, or a combination of methods, may be used if
the owner or operator can demonstrate to the Department that one of the
following exists:
(i) It can detect a 0.2
gallon per hour leak rate or a release of 150 gallons within a month with a
probability of detection of 0.95 and a probability of false alarm of
0.05.
(ii) It can detect a release
as effectively as any of the methods allowed in paragraphs (2)-(7). In
comparing methods, the Department will consider the size of release that the
method can detect and the frequency and reliability with which it can be
detected. If the method is approved, the owner and operator shall comply with
conditions imposed by the Department on its use to ensure the protection of
human health and the environment.
This section cited in 25 Pa. Code §
245.31 (relating to underground
storage tank system testing requirements); 25 Pa. Code §
245.403 (relating to
applicability); 25 Pa. Code §
245.434 (relating to repairs
allowed); 25 Pa. Code §
245.437 (relating to periodic
testing); 25 Pa. Code §
245.441 (relating to general
requirements for underground storage tank systems); 25 Pa. Code §
245.442 (relating to periodic
monitoring requirements for petroleum underground storage tank systems); 25 Pa.
Code §
245.443 (relating to requirements
for hazardous substance underground storage tank systems); 25 Pa. Code §
245.445 (relating to methods of
release detection for piping); 25 Pa. Code §
245.446 (relating to release
detection recordkeeping); and 25 Pa. Code § 252.3 (relating to
scope).
