NAPL Detection and Heron Oil/Water Interface Meters
NAPL detection and thickness measurement is often a critical environmental or engineering task. Non-aqueous phase liquid (NAPL) is described as petroleum or other fluid that is immiscible in water and tends to remain as a separate undissolved liquid in the subsurface. The determination of the depth and thickness of oil or other lighter than water fluid floating on groundwater is wells or boreholes, especially monitoring wells, is accomplished by several means. The method used is generally determined by accuracy requirements and if a need for relatively rapid measurements exists. Drillers often make an initial rapid measurement with a "plopper" on the end of a length of twine. The "plopper" consists of a cup shaped piece of metal that makes a "plopping noise" when it hits the water. Knots in the twine may indicate approximate depth intervals. The twine must be lowered through the NAPL layer to measure the thickness. It is difficult or impossible to determine the thickness of NAPL this way. Another, somewhat more refined method involves coating the bottom of the twine or a steel measuring tape with a compound that changes color when it is wet with NAPL that contrasts with the part that is wet with water. This method can be accurate, but it is slow and messy.
A clear bailer (transparent PVC or Teflon) is sometimes used to sample and measure the thickness of NAPL. This method is a good way to obtain a sample of the NAPL, but is not an an accurate way to measure the thickness because of the disturbance that is caused in the well.
Accurate measurements can be collected more easily with an electronic "oil/water interface" meter (or oil/water interface indicator or probe). Interface meters generally detect the oil/water interface by distinguishing the different angles of refraction of water and NAPL. They generally signal if they are in NAPL or water with different sound signals (eg. continuous beep versus short beeps) and/or light signals (often both).
Our product line includes Heron Instruments, Inc. products, manufacturers of oil/water interface and water level meters. These instruments are required by many of us in our daily work. With over thirty years of combined experience in the engineering, hydrogeological, and equipment design fields, Heron Instruments has developed the latest in water-level and oil/water interface meters. Oil/water interface and water level meters by Heron demonstrate durability, accuracy, and reliability. Heron Instruments may be ordered on this site directly by credit card or electronic check using the secure PayPal system. Some small-diameter well solutions are explored on our "Small-Diameter Well Quandray Page".
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||H.01L Oil/Water Interface Meter. The H.O1L oil/water interface meter is used to accurately measure the thickness of floating product (LNAPL) above the water table. The Sm.OIL Interface Meter fills the requirement for a SMALL low cost high quality meter for use in shallow monitoring wells. Click here for more information.|
|Sm.OIL A Small Interface Meter. The Sm.OIL Interface Meter fills the requirement for a SMALL low cost high quality meter for use in shallow monitoring wells. Click here for more information.|
|dipper-T Water-Level Meter. The Heron dipper-T Water Level Meter is a top of the line instrument providing exceptional value. Click here for more information.|
||Little Dipper Water-Level Meter. The small size and light weight of the little dipper make it the ideal instrument for "carry in" sites, shallow wells and direct push equipment. Click here for more information.|