Impervious Membrane: In accordance with the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, an impervious membrane is a continuous methane gas barrier. It is a crucial part of the methane mitigation process and underlies a building to impede the vapor intrusion of methane soil gas. An impervious membrane must comprise materials approved by the LADBS.
Igneous Rock Definition In the field of geology, the term “Igneous Rock” refers to one of the three major classifications of rock that comprises the earth. As opposed to sedimentary rocks or metamorphic rocks, igneous rock derives from the direct cooling and solidification of magmatic material. Igneous rock comprises a large amount of the planet…
Transgression Transgression: In geology, the term transgression is the formation of a specific sequence of sedimentary and metamorphic layers, that are the result of ocean water advancing onto land. To illustrate, when transgression occurs over millions of years, geologists find a layer of sand, overlain by shale, and overlain again by limestone. The opposite of…
Liquefaction Liquefaction: Liquefaction is the process by which there is: (1) a sudden and significant decrease of shear resistance in a soil sample (cohesion-less); (2) a sudden (but temporary) increase of the pore-water pressure of a substance; and (3) a solid mass of soil that is transformed into a fluid state mass. In the event…
Milliequivalent per liter Milliequivalent per liter (meq/L): A unit used to express the chemical equivalence of the concentration of solutes in a solution. It is calculated by dividing the concentration of a substance (in mg/L) by its equivalent weight. This measurement helps in understanding the reactive capacity of ions in the solution.
Hydraulic Conductivity (K) “Hydraulic Conductivity” (K), in hydrogeology and hydrology, represents the capacity of a porous medium (such as soil) to transmit water, as per Darcy’s Law. To illustrate, the rate at which fluid can move through a permeable medium (such as soil), depends on the properties of that soil (such as intrinsic permeability) and…
Thrust Fault Thrust Fault: In the field of geology, a thrust fault is a reverse fault in which the fault plane dipping angle is less than 45 degrees. Thrust faults are dip-slip faults, and can also be listric faults. For instance, the fault underlying the western embankment of the historical St. Francis Dam in Saugus,…
