The following terms are defines as used in this report:
Abandoned Well – A well whose use has been permanently discontinued or which is in such a state of disrepair that no water can be produced. Because abandonment is a state that also involves intent on the part of the well owner, a definition that prescribes a set of conditions and a time limit for use in applying standards appears in Section 21 of Chapter II, “Standards”, of this report.
Active Well – An operating water well.
Annular Space – The space between two well casings or between the casing and the wall of the drilled hole.
Aquifer – A geologic formation, group of formations or part of a formation that is water bearing and which transmits water in sufficient quantity to supply springs and pumping wells.
Artesian Well – A well which obtains its water from a confined aquifer. The water level in an artesian well stands some distance above the top of the aquifer it taps. Where the pressure is sufficient to force the water level above the surface of the ground, the well is termed a flowing artesian well.
Bailer – A long narrow bucket with a valve in the bottom used to remove cuttings or fluids from a well.
Bentonite – A highly plastic colloidal clay composed largely of montmorillonite used as a drilling fluid additive or as a sealant.
Casing – A tubular retaining structure which is installed in the well bore to maintain the well opening.
Clay – A fine-grained geologic material (grain size less than 0.004 mm in diameter) which has very low permeability.
Conductor Casing – A tubular retaining structure installed in the upper portion of a well between the wall of the drilled hole and the inner well casing.
Cone of Depression – A depression in the water table or piezometric surface of a groundwater body that is in the shape of an inverted cone and develops around a well which is being pumped. It defines the area of influence of the pumping well.
Confined Groundwater – Groundwater under pressure whose upper surface is the bottom of an impermeable bed or a bed of distinctly lower permeability than the material in which the confined water occurs. Confined groundwater moves under the control of the difference in head between the intake and discharge areas of the water body.
Connate Water – Water entrapped in the interstices of a sedimentary rock at the time it was deposited. These waters may be fresh, brackish, or saline in character. Usually applies only to water found in geologically older formations.
Consolidated Material - A geological material whose particles are stratified, cemented, or firmly packed together; usually occurs at depth, e.g. sandstone.
Contamination – Defined in Section 13050 of the California Water Code:
“(k) ‘Contamination’ means an impairment of the quality of the waters of the state by waste to a degree which creates a hazard to the public health through poisoning or through the spread of disease. ‘Contamination’ shall include any equivalent effect resulting from the disposal of waste, whether or not waters of the state are affected.”
Destroyed Well – A well that has been properly filled so that it cannot produce water nor act as a vertical conduit for the movement of groundwater.
Deterioration – An impairment of water quality.
Drilled Well – A well for which the hole is excavated by mechanical means such as the rotary or cable tool methods.
Driller’s Mud – A fluid composed of water and clay used in the drilling (primarily rotary) operation. The mud serves to remove cuttings from the hole, to clean and cool the bit, to reduce friction between the drill stem and the sides of the hole, and to plaster the sides of the hole. Such fluids range from relatively clear water to carefully prepared mixtures of special purpose compounds.
Drive Shoe - A forged steel collar with a cutting edge fastened onto the bottom of the casing to shear off irregularities in the hole as the casing advances, and to protect the lower edge of the casing as it is driven.
Gravel Packed Well – A well in which filter material (sand, gravel, etc.) is placed in the annular space between the casing and the borehole to increase the effective diameter of the well, and to prevent fine-grained material from entering the well during pumping.
Groundwater – That part of the subsurface water which is in the zone of saturation.
Groundwater Basin – A groundwater basin consists of an area underlain by permeable materials which are capable of storing or furnishing a significant water supply; the basin includes both the surface area and the permeable materials beneath it.
Grout – A fluid mixture of cement and water of a consistency that can be forced through a pipe and placed as required. Various additives, such as sand, bentonite, and hydrated lime, are used to meet certain requirements. For example, sand is added when considerable volume of grout is needed.
Impairment – A change in quality of water which makes it less suitable for beneficial use.
Impermeable – That property of a geologic material that renders it incapable of allowing water to move through it perceptibly under the pressure differences ordinarily found in subsurface water.
Impervious Strata – A geologic unit which will not transmit water in sufficient quantity to furnish an appreciable supply to wells or springs.
Inactive Well – A well not routinely operated but capable of being made an operating well with a minimum of effort.
Packer – A device used to plug or seal a well at a specific point; frequently used as retainers to keep grout in position until it “sets”.
Perforations – Openings in a well casing to allow the entrance of groundwater into the well. Perforations may be made either before or after installations of the casing.
Permeability – The capacity of a geologic material for transmitting a fluid. The degree of permeability depends upon the size and shape of the openings and the extent of the interconnections.
Pollution – Defined in Section 13050 of the California Water Code:
“(1) ‘Pollution’ means an alteration of the quality of the waters of the state by waste to a degree which unreasonably affects: (1) such waters for beneficial uses, or (2) facilities which serve such beneficial uses. ‘Pollution’ may include ‘contamination’.”
Quality of Water or Water Quality – Defined in Section 13050 of the California Water Code:
“(g) ‘Quality of the water’ or ‘quality of the waters’ refers to chemical, physical, biological, bacteriological, radiological, and other properties and characteristics of water which affect its use.”
Screen or Well Screen – A factory-perforated casing used in a well that maximizes the entry of water from the producing zone and minimizes the entrance of sand.
Tremie – A tubular device or pipe used to place grout in the annular space. Originally designed for placing concrete under water, the discharge end of the tube is kept submerged in the freshly deposited grout so as not to break the seal while filling the annular space.
Unconfined (free) Groundwater – Groundwater that has a free water table, i.e., water not confined under pressure beneath relatively impermeable rocks.
Unconsolidated Material – A sediment that is loosely arranged or unstratified, or whose particles are not cemented together occurring either at the surface or at depth.
Waste – Defined in Section 13050 of the California Water Code:
“(d) ‘Waste’ includes sewage and any/all other waste substances, liquid, solid, gaseous, or radioactive, associated with human habitation, or of human or animal origin, or from any producing, manufacturing, or processing operation of whatever nature, including such waste placed within containers of whatever nature prior to, and for purposes of, disposal.”
|Table of Contents     Appendix B|