What is a Concrete Slab and Buttress Dam? A Concrete Slab and Buttress Dam is a freshwater-retaining structure comprising reinforced concrete slabs that are supported in-place by buttresses. The foundation of a Concrete Slab and Buttress Dam receives a large load. Thus, the foundation must be structurally sound, impervious, and competent. The alternative types of dams…

Methane Alarm System Methane Alarm System: As per the Los Angeles Department of Building and Safety (LADBS) Methane Code, Ordinance Number 175790, a methane alarm system is part of an active methane mitigation plan. A methane alarm system is a group of interacting components and circuits that synchronize to monitor and annunciate the status of…

Thermosphere Thermosphere: The thermosphere of a terrestrial planet is the fourth and final member of the atmosphere. On Earth, the thermosphere starts atop the mesosphere at approximately 85 kilometers above mean sea level. The upper limit of the thermosphere is reasonably presumed to terminate approximately 95 kilometers above mean sea level. In fact, most of…

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…

Normal Fault Normal Fault: In the field of geology, a normal fault is a type of dip-slip fault where the hanging wall moves downwards from the footwall. The average dipping angle of a normal fault ranges from 45 to 90 degrees. Normal faults are the opposite of reverse faults. Detachment Fault Detachment Fault: A detachment…

Passive Methane Mitigation Passive Methane Mitigation: Passive systems refer to the non-mechanical and non-electric components of the methane mitigation process. These components remove the vapor intrusion risks of methane soil gas migration into buildings atop Los Angeles Methane Zones and Methane Buffer Zones. In fact, methane testing results typically indicate the necessity for a passive…