Environmental Engineering Reference
In-Depth Information
metals,.sulides,.and.some.hydrocarbons..Surface.contamination.by.coal.and.
coke.may.also.be.expected..The.retort.houses.on-site.are.loaded.with.coal.and.
heated. for. several. hours. to.drive.off. all.volatile.material,. resulting. in. coke.
that.is.removed.from.the.retort..Solid.process.residuals,.left.in.retort.houses,.
include. ash,. clinker,. and. coke.. The. carbureted. water-gas. process. residuals.
include.clinker.and.wastewater.containing.lighter.petroleum.hydrocarbons.
and. metals. (NZ. MFE. 1997).. Nickel,. uranium,. and. vanadium. catalysts. are.
often.left.on-site.where.oil.gas.production.takes.place..Tanks.and.pipe.works.
left. on-site. after. decommissioning. may. contain. residual. material.. Old. gas.
mains.are.sometimes.used.on-site.as.convenient.receptacles.for.waste.holder.
oil. and. water. during. decommissioning.. MGP. residuals. are. found. both. in.
surface. and. subsurface. soils;. tar. often. is. present. in. deep. subsurface. soils.
due. to. vertical. migration. along. preferential. pathways. (Sharon. and. Dennis.
Unites.1998).
Contaminants of Concern in MGP Sites
The.gas.manufacturing.processes.in.the.past.resulted.in.a.variety.of.residu-
als,. some. of. which. were. converted. to. by-products,. while. other. hazardous.
materials. were. managed. as. wastes.. The. detailed. processes. and. generation.
of. wastes. are. shown. in.Table.16.1.. Contamination. of. soil. and. groundwater.
in.MGP.sites.is.dominated.by.six.primary.classes.of.chemicals.(Luthy.1994,.
Middleton.1995,.Pradhan.and.Srivastava.1997),.which.include.the.following:
•. PAHs
•. Volatile.aromatic.compounds.(VACs)
•. Metals.(arsenic,.chromium,.copper,.lead,.nickel,.and.zinc)
•. Phenolic.compounds
•. Inorganic.nitrogen.(including.cyanide.compounds)
•. Inorganic.sulfur
Each. of. these. wastes. is. made. of. hundreds. or. thousands. of. different.
chemicals. (Table. 16.2).. These. chemicals. are. used. in. manufacturing. or.
are.produced.as.wastes,.individually. or.collectively,.in.industries.such.as.
petroleum.reineries,.wood.treatment.and.preservation,.coke.manufactur-
ing,.gas.plant.facilities,.and.synthetic.fuel.production.(Knight.et.al..1999)..It.
was.a.common.practice.to.dump.coal.tar.and.other.wastes.into.on-site.pits.
or. ponds,. bury,. or. use. as. ill. to. adjust. the. grade. of. the. gas. yard.. The. gas.
manufacturing.process.also.involved.the.use.of.wood.chips.and.iron.ilings.
to. remove. sulfur.and.cyanide. from. the. gas.. These. chips. and. ilings. were.
disposed. off. in. pits. or. buried.. As. a. result. of. these. practices,. wastes. from.
manufactured.gas.processing.can.be.found.in.soil,.sediment,.groundwater,.
and.surface.water.(Fischer.et.al..1999,.US.EPA.2004).
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