Ministry of Environment

Guidelines for Environmental Monitoring at Municipal Solid Waste Landfills

Section 1.0: Definitions

"adjacent property" refers to a property near a landfill that might be impacted by the landfill's presence and operation (e.g. litter, landfill gas or leachate migration, etc.).

"annular space" means the space between the borehole wall and the well casing, or the spacing between a casing pipe and a liner pipe.

"aquifer" includes any soil or rock formation that has sufficient porosity and water yielding ability to permit the extraction or injection of water at reasonably useful rates.

"attenuation" a process whereby contaminants generated in a landfill are managed, removed or reduced in concentration. Attenuation involves the processes of dilution, filtration, chemical reaction and transformation and may be accomplished naturally under certain conditions.

"contaminant" means a chemical compound, element, or physical/biological parameter, resulting from human activity, or found at elevated concentrations, that may have harmful effects on human health or the environment.

"groundwater" means water below the ground surface in a zone of saturation.

"hydraulic gradient" means the change in static head per unit of distance in a given direction.

"infiltration" is the entry into soil or solid waste of water at the soil or solid waste surface.

"in-situ testing" means testing in the field of materials or naturally occurring substances in their original state.

"landfill gas" is gas produced by the anaerobic decomposition of solid wastes, and includes primarily methane and carbon dioxide, with lesser amounts of other gasses such as hydrogen, hydrogen sulphide, and numerous volatile organic compounds.

"leachate" means any liquid and suspended materials which it contains, which has percolated through or drained from a municipal solid waste disposal facility.

"leachate plume" means contaminated groundwater or soil, beyond the limits of the deposited waste which has been contaminated by leachate from the landfill site.

"lower explosive limit" means the minimum percent concentration (by volume) of a substance in air that will explode or produce a flash of fire when an ignition source is present, measured at 25 degrees Celsius and atmospheric pressure.

"monitoring well" is a water well used to monitor groundwater and occasionally gaseous conditions in the vicinity of a landfill.

"NMOCs" are non-methane organic compounds, primarily composed of VOCs, which contribute to ground level ozone formation. Also known as non-methane hydrocarbons.

"piezometer" is a small diameter, non-pumping well that measures hydraulic and aquifer characteristics such as hydraulic head pressure and compressibility. Piezometers can also be used for groundwater sampling.

"purging" means the removal of stagnant water from a monitoring well casing.

"static head" means the distance from a standard datum of the surface of a column of water that can be supported by the static pressure at a given point.

"surface water" means lakes, bays, sounds, ponds, impounding reservoirs, perennial or ephemeral streams and springs, rivers, creeks, estuaries, marshes, inlets, canals, the Pacific Ocean within the territorial limits of British Columbia, and all other perennial or ephemeral bodies of water, natural or artificial, inland or coastal, fresh or salt, public or private, but excludes groundwater or leachate collection channels or works.

"vadose zone" means a subsurface zone above the water table in which the interstices of a porous medium are only partially filled with water.

"VOCs" are volatile organic compounds, which participate in atmospheric photochemical reactions, related to the generation of ground level ozone. VOCs are a subset of NMOCs.

"well development" means the restoration of natural hydraulic conditions in a monitoring well after drilling accomplished by removing any silt or sand sized particles from the filter pack and surrounding formation.

"well nest" means a closely spaced group of wells screened at different depths, whereas a multi-level well is a single device with two or more monitors sealed at different depths.