For typical containers,. such as 55 gallon drums;··EP A recommends th~Ui container cover be properiy s~cured with
snap rings tightly bolted; b~ngholes capped,. and; wh~re appropriate, pres'sure-vacuum relief valves· t~ maintain the .
cont~iner s internal p~e sure to:avoid·explo;;ions. EPA 'generally considers a co~ta~erac umulat ing free liquids or
liquid hazardous.' wastes to be ·~closed" whein all openings or )ids. are properly and secllrely affixed to the container,
except when wast~s are _actually b~ing adde-d to or re ved om t~econtainer. Contai'ners holding free liquids or
liquid hazardous wastes i~ an SAA wo:uichneet the regUatmy .deflriition of"closed" usin_g manually or spring
closing lids or other similar deY;ices:for ~losed head oi"closed-top drums· (e.g.; .coritalilei"s th3lt have two bung holes
with non-removable !ids). Fun:"ners ~s d to a.dd or remov~)lqliidvastes would be screwed tightly to the bunghold
and fitted with a gasket, if ne~essary, to .sea II the funne l' lid"flnhly os~d unnet _lids ~r: ~lo~eq-head and closed-top
drums may be fitted with a locJgng mechaniism. Alternatively, the gerier.ator may .use a funnd witha one-way valve
that allOWS hazardOUS. waste to nter the con1tainer but prohibits the waste or emissions from exit.ing the container.
Liquid hazardous wastes also can be accumulated in open-head drums or pen top·.~ontainers (e.g., where the entire
lid is removable and typically" secured with a ring .and. bolts or snap ring) and meet the definition of."closed"
provided the rings are clamped or bolted to the ntain~r. T he container could be considered closed ifthe lid covers
the container top securely. For solid and ·sern.i-solid hazardous wastes, EPA considers the container "closed" as long
a.s there is complete contact b.etween the lid and the. rim all around the top of the container.. Contai~ers continuously
or intermittently receiving solid.or semi-~ol id was~es (e.g., under a baghouse,ot tiltei: pr~s~) should be capable of
catching and retaining all oftl;le materjalduring transfer fi:om a device to .the ·container. 9ont.airiers with covers
opened by a foot pedal (e.g., flip-top o~· spririg loaded lid) or with a self-closing sw in~ing door may also be .
appropriate. For other types ofcontain , EPA considers them "closed" wherithey- a.i-e se~led 'to. the ~xtent
necessary to keep the hazardous .vaste and associated air emissions inside the container: