Pili ia i nā wahi pilikia i loaʻa i ka methane (ʻike maʻamau ʻia ʻo ke kinoea) a me ka pahū o ka coal0dust, hiki ke hoʻohana i ka sewerage i loaʻa i kahi hui o nā mea paʻa paʻa ʻole e like me ka sediment, coal slime, cinders, fibrous material, etc.
