Topics covered in this file include how 40 CFR 280 applies to the
following:

-   oil/water separators

-   recast concrete vaulted tank system housing a tank below grade

-   mixtures of gasoline and methanol

-   heating oil tanks

-   compartmentalized USTs

-   vaulted tank systems

-   sumps used to contain diesel fuel discharges from electric power
    generation turbines

-   diesel fuel being burned as heating oil

-   the threshold value for declaring an UST or its piping to be leaking
    using a tightness test

-   closure requirements for tanks that were closed nearly 30 years ago

-   tanks that have not been in operation since 1980

-   size of the overfill catch basin

-   reporting of old releases.

**Question**: Do the 40 CFR Part 280 requirements apply to process waste
traps (oil-water separators)?

> **Answer**:
>
> \[The answer is drawn from a letter sent by Thomas Schruben, Office of
> Underground Storage Tanks in response to an inquiry dated December 2,
> 1988 .\]
>
> Some UST systems are excluded from RCRA Subtitle I regulation in the
> statute (For example, septic tanks and stormwater or wastewater
> collection system tanks). RCRA Subtitle I does not include a specific
> exclusion of oil-water separator tanks, however.
>
> The final EPA technical standards provide further regulatory
> definition of the various exclusions and also contain regulatory
> exclusions and deferrals (from most RCRA Subtitle I regulatory
> coverage) of various UST systems. In general , oil water separator
> systems are either excluded or deferred from the regulation.
>
> Wastewater treatment tank systems that are part of a wastewater
> treatment facility and are subject to regulation under either section
> 402 or 307 (b) of the Clean Water Act (CWA ) are excluded from all
> RCRA Subtitle I regulation.
>
> Oil/Water Separators That Discharge to a POTW
>
> All publicly owned treatment works (POTW) and many private treatment
> facilities are subject to the CWA and therefore excluded from
> regulation under 40 CFR Part 280. Facilities regulated under the CWA
> are required to be permitted in order to discharge treated water to
> any U.S. surface waters \[i.e., the NPDES program\]. Because of this,
> EPA has decided that additional regulation under RCRA Subtitle I is
> unnecessary to protect human health and the environment.
>
> If your oil water separators are discharging to a POTW and thus must
> meet treatment standards under 307 (b), your oil water separators are
> excluded from regulation under 40 CFR Part 280.
>
> Oil/Water Separators that do not discharge to a POTW or have a NPDES
> permit
>
> Tank systems that treat wastewater or stormwater, but are not subject
> to Section 402 or 307(b) of the CWA, are deferred from having to meet
> the requirements of subparts B through E and G. Such tanks include
> oil-water separators that do not discharge to a POTW or have an
> National Pollution Discharge Elimination System (NPDES) permit (or
> subject to a zero discharge effluent guideline). Tanks that pretreat
> and hold wastewater that is periodically removed and hauled by truck
> to a treatment facility may be in this category. Under this regulatory
> deferral, such tanks would still have to comply with corrective action
> (should a release occur) and financial responsibility requirements of
> Subpart H.
>
> Field --constructed Tanks
>
> Similarly, field-constructed tanks are deferred from the requirements
> in 40 On Part 280, subparts B through E and G of the final UST
> regulations. Generally these tanks are made of concrete or constructed
> at the site (for example, concrete poured into forms or otherwise
> fabricated in the field). EPA has deferred the application of the
> regulations (except for corrective action and financial responsibility
> requirements)

**Question**: Is a recast concrete vaulted tank system housing a tank
below grade exempt from 40 CFR Part 280 requirements?  \[July 5, 1989
request from Virginia via Region III\] 

> **[Answer]{.underline}**: Yes, \"if the tank sits upon or above the
> surface of the floor and there is sufficient space to enable physical
> inspection of the tank bottom.\" (53 FR 37121) 

**[Question]{.underline}**: Are mixtures of gasoline and methanol,
(e.g., M85), to be treated as motor fuel or hazardous substances under
40 CFR Part 280?  \[July 14, 1989 request\] 

> **[Answer]{.underline}:** M85 must be stored in a hazardous substance
> UST system because it contains 85 percent of a CERCLA-listed
> substance. Gasohols containing lesser amounts of methanol (generally,
> 2.5 to 5 percent) may be stored in petroleum UST systems. M85 can be
> stored in petroleum UST systems if a variance can be obtained, where
> allowed, by the implementing agency in accordance with the rule\'s
> requirements. 

**Question**: Does my tank qualify for the heating oil tank
exemption? \[1990 referrals from several EPA regions\]

**[Answer]{.underline}:** See the [UST Decision Tree (UST Decision
Tree.pdf)]{.underline}

**[Question]{.underline}:** Are compartmentalized USTs considered one
tank for purposes of regulation? \
 \[May 14, 1991 letter\]

> **[Answer]{.underline}:** Compartmentalized tanks, and piping
> connected to it, are considered one tank system by EPA because they
> are manufactured, transported, installed, protected from corrosion,
> and often equipped with leak detection as a single unit. Please check
> with your State or local agency as they may interpret this question
> differently. 

**[Question]{.underline}:** When are vaulted tank systems excluded from
UST regulations? \
\[August 21, 1991 letter\]

> **[Answer]{.underline}:** Tanks that are not supported by backfill,
> can be visually checked for evidence of leaks, and are built and
> installed to aboveground tank codes are not subject to EPA\'s UST
> regulations. In the example given, a vaulted tank system wherein the
> tank is within six inches of the vault on three sides and set back far
> enough on the fourth side for entry and inspection is not subject to
> the agency\'s UST regulations if the access provided on the fourth
> side is sufficient to observe evidence of a leak from anywhere on the
> tank vessel. 

**[Question]{.underline}:** Does the emergency spill of overflow
containment exemption of 40 CFR 280.10(b)(6) apply to sumps used to
contain diesel fuel discharges from electric power generation turbines? 
\[August 28, 1991 letter\] 

> **[Answer]{.underline}:** The sumps are not used for an emergency
> spill, leak, or other unplanned occurrence. The sumps are designed to
> collect diesel fuel from an electric power generation turbine
> immediately after a false start. While these false starts are
> periodic, they are not emergencies. Therefore, the false start sumps
> described in your letter are subject to the 40 CFR Part 280
> requirements. 

**[Question]{.underline}:** Diesel fuel is stored in an underground
tank.  The diesel fuel is burned as a substitute for heating oil in an
on-site furnace.  The definition of underground storage tank (UST) in 40
CFR 2801.2(b) excludes any tank used for storing heating oil for
consumptive use on the premises where stored.  Does the underground tank
storing diesel fuel meet this exclusion? 

> **[Answer]{.underline}**: An underground tank storing diesel fuel will
> meet this exclusion if the diesel fuel will be substituted for heating
> oil; i.e., burned in a unit designed to use heating oil.  the
> exclusion to the definition of UST in subsection 280.12(b) as No. 1,
> No. 2, No. 4-light, No. 4-heavy, No. 5-light, No. 5-heavy, and No. 6
> technical grades of fuel oil; residual fuel oils (including navy
> Special Fuel Oil and Bunker C) and fuel substitutes such as kerosene
> and diesel fuel when used for heating purposes (53 [FR]{.underline}
> 37117; September 23, 1988).  A tank storing diesel fuel that will be
> burned as an alternative to one of these eight types of heating oil in
> a unit designed to burn heating oil is excluded from the definition of
> UST.  If on the other hand, the diesel fuel is being used for some
> other purpose, such as to power an internal combustion engine or an
> emergency generator, the tank would not meet this exclusion.  The
> question of whether tanks associated with emergency power generators
> are excluded from the UST definition under the heating oil exclusion
> is somewhat complex.  A discussion on page 37118 of the September 23,
> 1988 [Federal Register]{.underline} specifically addresses such tanks
> and indicates that the use of heating oil itself is not limited to
> heating, but may include other on-site uses, such as emergency
> generators.  This discussion does not incorporate or address the
> stipulation that USTs containing fuels other than heating oil are only
> exempt if the fuel is burned as a substitute for heating oil in units
> designed for heating oil.  Therefore, the language on page 37117
> should be consulted for tanks containing other fuels such as diesel
> fuel. 
>
> The second part of the exemption involves the meaning of consumptive
> use.  The exclusion applies to heating oil used at the same site where
> it is stored, but not to heating oil that is stored prior to resale,
> marketing or distribution.  Consumptive use of heating oil is not
> limited to burning in a heater, but instead is defined as an on-site
> use (53 [FR]{.underline} 37117).  Therefore, the subsection 280.12(b)
> exclusion from the definition os UST applies to (1) tanks storing one
> of the eight technical grades of fuel oil prior to any on-site use,
> and (2) tanks storing fuel oil substitutes prior to use for on-site
> heating purposes only. 

**[Question]{.underline}:** Please clarify EPA\'s UST regulations as
they apply to a threshold value for declaring an UST or its piping to be
leaking using a tightness test.\
 \[November 11, 1988 letter\]

>  **[Answer]{.underline}:** To be able to detect a 0.1 gallon per hour
> (gph) leak as required in the regulations at a statistically reliable
> level of confidence, the threshold must be smaller than 0.1 gph. The
> correct threshold depends on the particular leak detection system and
> UST system, but is traditionally and typically 0.05 gph.

**[Question]{.underline}**: What are the closure requirements for tanks
that were closed nearly 30 years ago?  \[January 25, 1990 letter\]

>  **[Answer]{.underline}**: The Federal regulations do not require
> owners and operators of previously closed tanks to comply with the
> Federal closure provisions unless directed to do so by the
> implementing agency.

**[Question]{.underline}**: Are tanks that have not been in operation
since 1980 subject to Federal closure requirements? \[March 1, 1990
letter\]\
 

> **[Answer]{.underline}**: No, however, each State implementing agency
> can adopt closure standards that are more stringent than the Federal
> standards.

**[Question]{.underline}:** Do the national codes or the final rule deal
with the size of the overfill catch basin\--are there specific
requirements for minimum volumes? 

> **[Answer]{.underline}**: No limits are established by national codes
> or in the final regulations concerning the size of the catch basins
> that must be used. Because these basins are for small spill
> containment, they should be able to contain volumes of at least one to
> two gallons. The standard size on the market is five gallons. 

**[Question]{.underline}:** Do old releases have to be reported?

>  **[Answer]{.underline}:** Yes, owners and operators of USTs subject
> to the final rules must report both suspected and confirmed releases
> (see 40 CFR Part 280.50-3). There is no regulatory distinction between
> old or new releases, and it is technically difficult, if not
> impossible, to determine the age of a release. The implementing agency
> can require proper closure (including site assessment) and corrective
> action at old sites suspected of having a release.