NAPL Flute FAQ: Frequently Asked Questions

For subsurface in situ measurements, NAPL Flutes are installed in stable open boreholes on blank liners or through driven casing such as direct-push rods.

Yes. A folded strip of the reactive cover material can be inserted in a split core, but evaporation of some NAPLs should be avoided. Ask for the recommended procedure. Sonic core can be extruded into a tubular cover of the reactive cover material.

Yes, for the use in direct push rods, an injection pump is needed. A wellhead roller and winch is needed for the installation and removal from open stable holes. Direct push liners are usually easily pulled from the hole by hand (the liner should be filled to the top when that is done).

For subsurface installations, at least 10 minutes, but an hour is recommended. A video is available showing the reaction of the reactive material to TCE and to gasoline.

No. Because the hydrophobic cover material aggressively wicks the NAPL/DNAPL, it will exaggerate the thickness. The size of a stain is a better measure of the quantity available rather than the thickness of free product.

Usually within a week of the order. However, it depends on the schedule of other Solinst Flute fabrications. An early order is better.

Yes. But, there is some training required. Explicit instruction in the procedure is available. If desired, a Solinst Flute field person can provide on-site training and assistance with the first installations.

Yes. The reactive cover material is sometimes used to assess core or is lowered into a well to detect the presence of a thin layer of DNAPL at the bottom of the well.

Yes, the procedure is similar to the installation through direct push rods. However, it is best done by Solinst Flute.

A false positive (i.e., an obvious stain with no NAPL present) is very unlikely. No stain only means that the cover did not contact NAPL. It does not mean that the NAPL is not nearby.

No. It does not react to the dissolved phase, but only to contact with the pure product. The FACT system (Flute Activated Carbon Technique) added to the NAPL cover will measure the dissolved phase.

Yes. It is common practice to reinstall the blank carrier liner alone to seal the borehole after the reactive cover has been removed. It is also common practice to perform a transmissivity profile of the borehole with the carrier liner reinstallation.

No. It is very difficult to replace a cover on a carrier liner in the field without the special Solinst Flute equipment. It is also a concern that NAPL on an old liner might cause a stain on a new cover.

Generally, no. In order to examine the cover, it must be removed from the liner.

A NAPL Flute is usually installed to the bottom of the hole to assess the presence of DNAPL in the bottom of the hole. Therefore, the liner must be at least as long as the hole depth. It is not unusual to install a NAPL Flute which is longer than the actual hole depth.

No. The liner must be at least as long as the rods plus ~5 ft. The liner must protrude from the bottom of the rod after the first rod section is removed. A shorter liner may also allow sand to flow into the bottom of the rod and prevent the liner descent relative to the rod.

Yes. A tip slightly larger than the rod diameter is needed. It will be left in place when the first rod section is raised for removal. The tip should not be pounded out of the end of the rod before the liner is emplaced in the rod and the tip must be lubricated to easily remain in place at the bottom of the hole.

An id of 1.5 to 2.5 inches is readily compatible with hole sizes of 2.25 to 3.5 inches. Smaller inner diameter systems have been built, but are a special order.

Not if potable water was used for the installation. Hence there is not usually a need to dispose of IDW with the NAPL Flute system in direct push holes. However, the well water that may be produced from the well via a pump tube to the bottom of the well during the installation of a NAPL Flute into an open stable hole is considered contaminated.

Only if they are open and stable after the auger is removed. There is a concern about the smearing of NAPLs by the augering process.

Surging to remove cuttings from the fractures is reasonable, but very heavy pumping may remove the NAPLs from their normal locations and produce no stains on the NAPL Flute.

Core-holes have often been successfully assessed with NAPL Flute(i.e., staining was observed in fractures flowing DNAPL). It is recommended that one borehole water volume be removed as the liner descends to allow the NAPL Flute to seal inflowing fractures. However, that is not essential to detect fractures filled with DNAPL.

No. However, there are obvious differences in the nature of the stain between NAPLs with varying degrees of solvent capability (e.g., TCE, versus gasoline, versus oil). The color of the NAPL usually also contributes to the color of the stain. The geometry of the stain sometimes is important to the interpretation.

FACT stands for “Flute activated carbon technique” The FACT uses a strip of activated carbon felt attached to the inside surface of the NAPL FLUTe cover. A diffusion barrier isolates the felt strip from the liner. The liner presses the carbon felt strip against the hole wall which allows the activated carbon to absorb contaminants from the pore fluid of the hole water material. The result is a replica of the contaminant distribution dissolved in the pore liquid and the fractures as it is absorbed in the carbon felt. The carbon strip is withdrawn with the NAPL cover and is sectioned and analyzed with a mass spectrometer for contaminant concentration in the carbon. The FACT is often used in combination with a Solinst Flute transmissivity profile to identify the intervals of carbon strip to be analyzed.