Contaminated and Hazardous
Waste Site Management Glossary
R
Radar:
A system whereby short electromagnetic waves are transmitted and any energy which
is scattered back by reflecting objects is detected. Acronym for "radio detection
and ranging".
Radius
of Influence: The radial distance from the center of a wellbore to the point where
there is no lowering of the water table or potentiometric surface (the edge of
its cone of depression). The radial distance from an extraction well that has
adequate air flow for effective removal of contaminants when a vacuum is applied
to the extraction well. Reagent:
A substance or solution used in a chemical reaction, especially those used in
laboratory work to detect, measure, or produce other substances. Reagent
Blank: A volume of deionized/distilled water containing the same acid matrix as
the calibration standards carried through the entire analytical scheme. Reagent
Water: Water in which an interferant is not observed at or above the minimum quantitation
limit of the parameters of interest. Realization:
One simulation of a hydrogeological problem using one set of input parameters.
Normally, many realizations are produced and the statistical distribution of results
examined. Recalcitrant:
Unreactive, nondegradable; refractory. Receiver:
The part of an acquisition system which senses the information signal. Recharge:
Addition of water to the groundwater system by natural or artificial processes. Recharge
Area/Zone: Area in the aquifer where there are downward components of hydraulic
head. In this area, infiltration travels downward into the deeper sections of
the aquifer. Reclaimed
Surface: The shallow surface zone which was contaminated, but has been cleaned
up. Reconnaissance
Sampling: A non-systematic sampling, in which sampling locations are based, in
large part, on knowledge about the site. For example, former lagoon sites could
be selected for sampling, while unused areas of the site are not sampled. Record
of Communication: A register of all verbal communications between the EPA and
citizens regarding site concerns. Reconstructed
Ion Chromatogram (RIC): A mass spectral graphical representation of the separation
achieved by a gas chromatograph; a plot of total ion current versus retention
time Recovery:
The rise in static water level in a well, after discharge from that well or a
nearby well has ended. Redox: short for oxidation-reduction. Redox
Level: The level of oxidation in a redox system which is a chemical system in
which reduction and oxidation reactions occur. Reducing
Conditions: Geochemical conditions favouring reduction reactions (e.g., SO4- conversion
to H2S). Indicated by the occurrence of reduced forms of iron (Fe2+) and other
species. Reflection
Coefficient: A term used in seismic reflection and GPR to describe the ratio of
the reflected to incident amplitudes of a pulse reflected from an interface. Refractory
Index: A measure of the ability of a substance to be biodegraded by bacterial
activity. The lower the refractory index, the greater the biodegradability. Relative
Percent Difference (RPD): As used in the SOW and elsewhere to compare two values,
the relative percent difference is based on the mean of the two values, and is
reported as an absolute value (i.e., always expressed as a positive number or
zero). In contrast, see Percent Difference above. Relative
Permeability: The permeability of the rock to gas, NAPL, or water, when any two
or more are present, expressed as a fraction of the single phase permeability
of the rock. Relative
Response Factor (RRF): A measure of the relative mass spectral response of an
analyte compared to its internal standard. Relative Response Factors are determined
by analysis of standards and are used in the calculation of concentrations of
analytes in samples. RRF is determined by the following equation: A = area
of the characteristic ion measured c = concentration is = internal standard
x = analyte of interest Remanent
Magnetization (Remanence): Magnetization remaining after the application of magnetic
field has ceased. Remedial
Action (RA): The actual construction or implementation phase of a Superfund site
cleanup following the RD. Remedial
Design (RD): A phase of site cleanup where engineers design the technical specifications
for cleanup remedies and technologies. Remedial
Investigation (RI): An in-depth study designed to gather the data necessary to
determine the nature and extent of contamination at a Superfund site, establish
the criteria for cleaning up the site, identify the preliminary alternatives for
cleanup actions and support the technical and cost analyses of the alternatives.
The RI is usually done with the FS. Together they are customarily referred to
as the RI/FS. Remediation:
The clean up of contaminated soil or groundwater. Removal
Action: Short-term, immediate actions taken to address releases of hazardous substances. Residual:
The amount of a pollutant remaining in the environment after a natural or technological
process has taken place, e.g., the sludge remaining after initial wastewater treatment,
or particulates remaining in the air after the air passes through a scrubbing
or other process. Residual
Saturation: Saturation below which fluid drainage will not occur. Resistivity
(electrical): Electrical resistance to the passage of a current, expressed in
ohm-meters; the reciprocal of conductivity. Resolution:
Also termed separation or percent resolution, the separation between peaks on
a chromatogram, calculated by dividing the depth of the valley between the peaks
by the peak height of the smaller peak being resolved, multiplied by 100. Retardation,
Retard: Retention of certain contaminants in the subsurface due to one or more
physical, chemical, or biological factors. Also known as attenuation. Rotary
Drilling: A hydraulic drilling process which uses a hard-toothed bit attached
to a rotating drill pipe. Cuttings are carried up by circulating a drilling fluid.
Roughness:
A parameter describing a surface characteristic of a fracture plane. Roughness
is important in determining resistance to flow. Rounding
Rules: If the figure following those to be retained is less than 5, the figure
is dropped and the retained figures are kept unchanged. As an example, 11.443
is rounded off to 11.44. If the figure following those to be retained is greater
than 5, the figure is dropped and the last retained figure is raised by 1. As
an example, 11.446 is rounded off to 11.45. If the figure following those to be
retained is 5, and if there are no figures other than zeros beyond the 5, the
figure 5 is dropped and the last-place figure retained is raised by 1 if it is
an odd number or it is kept unchanged if it is an even number. As an example,
11.435 is rounded off to 11.44, while 11.425 is rounded off to 11.42. If a series
of multiple operations is to be performed (add, subtract, multiply, divide), all
figures are carried through the calculations. Then the final answer is rounded
to the proper number of significant figures. Run:
A continuous analytical sequence consisting of prepared samples and all associated
quality assurance measurements as required by the Contract Statement of Work.
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