“Effective Size” (D10) is an engineering geology term. Effective Size represents a diameter that directly corresponds to the percentage, by weight, of grains that equal to 10% on the grain-size diagram. To illustrate, 10% of the soil sample particles are finer-grained, and 90% of the sample particles are coarser than the “effective size.”
Consistency The term “Consistency” in the fields of engineering geology and geotechnical engineering means the degree of adhesion between soil particles within a sample, that are observed to resist deformation or rupture.
Confined Aquifer Confined Aquifer: In the hydrogeology branch of geology, a confined aquifer is an aquifer that is overlain (and underlain) by a layer of low permeability, such as clay, shale, or silty clay. In fact, the two confining layers contain the storage and flow of groundwater, such that the aquifer maintains hydraulic pressure (or…
Design Methane Concentration Design Methane Concentration: In accordance with the Los Angeles Department of Building and Safety Methane Code, Ordinance Number 175790, a Design Methane Concentration is the highest recorded concentration of methane soil gas detected during the course of methane testing on a property. The Design Methane Concentration is what defines the level of…
Metamorphic Rock Definition In the field of geology, the term “Metamorphic Rock” refers to a rock classification that is the result of the alteration of prior existing sedimentary rocks or igneous rocks. The alteration process is “metamorphosis, and can take place by various methods and environments. The metamorphosis process produces specific metamorphic rocks, on the…
Well Graded Soil Well Graded: In the soil classification process of geology, well graded soil represents a sedimentary soil sample that fully displays all of the possible grain sizes for that soil classification, in accordance with the Unified Soil Classification System (USCS). For example, a well graded sand (SW) comprises fine, medium, and coarse grains…
Mechanical Extraction System Mechanical Extraction System: Per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a Mechanical Extraction System is one of the Active Methane Mitigation criteria for methane mitigation systems in buffer zones and methane zones. A mechanical extraction system uses machines that remove methane gas from below…
