Soil Vapor Extraction (SVE) is the primary technology for removing VOCs and other contaminants from the vadose zone of the soil matrix of a contaminated site.  Vacuum is applied to a recovery well where the screened portion of the well is exposed to the vadose zone.  Vacuum levels typically range from 30"WC on a very sandy soiled (high permeability) site to very deep vacuum levels of 28"HG on very tight clay soiled (low permeability) site.  Blowers for remediation of these sites are dominated by regenerative and rotary lobe blowers. Liquid Ring and Vane blowers are used on projects that require the much deeper vacuum.

PRM uses our MS series of Moisture Separator with all Soil Vapor Extraction systems

When used in conjunction with air Sparging systems, cleanup activities can be accomplished very aggressively and the technology can complete site cleanups in very short time periods.

BLOWERS USED FOR SOIL VAPOR EXTRACTION

DESIGN CONSIDERATIONS

Always consider friction losses for moisture separator tanks, header piping and groundwork piping when designing a Soil Vapor Extraction system.  Losses due to undersized piping is one of the most attributable factors in poor system performance due to low applied vacuum at the well head. Example: 10"Hg applied at the blower and 6" Hg applied at the well head constitutes a 40% loss of vacuum due to poor design.

Actual design requirements for Soil Vapor Extraction systems should be confirmed with pilot testing.

BLOWER SELECTION

Blowers should be selected based on performance, longevity and efficiency.  Other considerations should be also taken into account such as noise which can impact the surrounding neighbors of a remediation system.  Noise is usually the single largest complaint in regards to noisy blowers that operate 24/7.  Please contact PRM in regards to the recommended blower for Soil Vapor Extraction applications.

MOISTURE SEPARATORS

All PRM moisture separators are designed to withstand high vacuum in excess of 29" Hg.  All tanks are made from heavy gauge material thicknesses to withstand warping or possible implosion. Filter housings are an integral part of the PRM moisture separator which reduces friction losses and simplifies piping assemblies in a Soil Vapor Extraction system.  3 stem floats are commonly installed in a site tube to manage moisture levels within the moisture separator.  The 2" site tube assembly (viewable in this picture)  is manufactured from 2" Sch. 80 PVC materials and the stem float is always removable via a quick camlock connector at the head of the site tube.  PRM moisture separators are held off of the skid surface approximately 1/4".  This inhibits the potential of rust and corrosion due metal to metal contact that typically occurs. This has been a weak point of many MS tanks where tank failures has occurred.

Click here to view recent photographs of Soil Vapor Extraction systems manufactured by PRM

AIR SPARGING

Air Sparging is a technology typically used in conjunction with SVE systems.  PRM brings years of experience in providing the best packaged air sparing systems available. Air Sparging is the application of injecting pressurized air below the water table and transferring oxygen from the air into the water.  The transfer of oxygen into the water serves to volatilize contaminants as well as to increase biological activity in order to assist in destruction of contaminants.

As hydrocarbons are volatized, they are transferred from the water matrix to the air matrix where they can be removed by an active SVE system.

BLOWERS USED

DESIGN CONSIDERATIONS

It takes 1 psig to depress 2.31' of water column. 

Consideration must be given for safety factor and geological friction losses. 

• In sandy soils, a safety factor of 1.3 is recommended for required pressure.
• In tighter, silty soils, a safety factor of 1.6 is recommended
• In tight claylike conditions, a safety factor of 2-3 is recommended.

Actual design requirements should be confirmed with pilot testing.

BLOWER SELECTION

Blowers should be selected based on performance, longevity and efficiency.  Other considerations should be also taken into account such as noise which can impact the surrounding neighbors of a remediation system.  Noise is usually the single largest complaint in regards to noisy blowers that operate 24/7.  Please contact PRM in regards to the recommended blower for the application.

Click here to view recent photographs of Air Sparging Systems manufactured by PRM