Maximum Soil Screening Levels (MSLs) Maximum Soil Screening Levels (MSLs): MSLs are a list of risk-based hydrocarbon concentrations for soil pollution evaluations, that is developed by the California Regional Water Quality Control Board. These screening levels are based on the Leaking Underground Fuel Tanks (LUFT) Manual, for cleaning up soil contamination from leaking USTs. However, MSLs…

Effective Size (D10) “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…

Mineral Definition A mineral is defined as an inorganic element, compound, or substance that naturally develops with an organized internal structure and/or crystal form over time. Minerals are also distinguishable by their chemical composition and physical properties, as determined in laboratories by geologists. Typical earth minerals found in most igneous, metamorphic, and sedimentary rocks are…

Runoff (R) The term “Runoff” (R) in hydrogeology and geology refers to the part of rainfall which accumulates on the ground surface and naturally forms into flowing streams.

Listric Fault Listric Fault: In the field of geology, a listric fault refers to a fault with a curved fault plane. Most listric faults comprise a steeply dipping section near the surface. But the fault plane becomes increasingly flat with depth. Listric faults can be normal faults or reverse faults.