Groundwater Remediation

Efficiency of Remediation

The Leakwise ID-225 Hydrocarbon Thickness can Monitor is capable of monitoring hydrocarbon layers in the range of 1–200 mm (8 in). This sensor can be used during remediation to indicate the efficiency of remediation by monitoring online the thickness reduction of free oil layers.
ID-225 Sensors installed in sites with many recovery wells can be used to assist in determining pumping strategy. For example, the project manager can decide to pump from wells with thicker hydrocarbon layers.

Remediation Pump Control

The ID-221 Detector and ID-225 Oil Thickness Monitor can be used to start and stop pumps upon detection of free oil layers, thus reducing the amount of water that is otherwise pumped out with the oil and saving on treatments costs. “Pump and treat” sites are very costly because they mainly treat water for long periods of time. The use of ID-221 Sensors may save much of these costs. In sites with pump and treat remediation, the ID-221 Detectors can be installed in peripheral wells. These detectors will activate pumps in remediation wells only when oil is detected and thus increase the probability that oil will be recovered – not just water.

Skim Control in Oil/Water Separator

Some skimming pumps operated by conductivity sensors will pump substantial amounts of water together with the oil. An ID-225 hydrocarbon thickness monitor installed in a separator can activate the skimming pump at a certain thickness of hydrocarbon layer (for example, at 100 mm) and stop the pump at a reduced thickness (for example, at 10 mm) until additional thickness growth is detected again. This method ensures that only hydrocarbons and no water will be removed and reduces the high costs of transporting large quantities of water with the oil, saving unnecessary treatment costs.

Protection of Air Stripper, Biological Treatment System, Activated Carbon

Water with dissolved oil is pumped out of the separator for treatment in an Air Stripper, Biological Treatment System, or Activated Carbon. A free hydrocarbon layer, which may be present in the water, can clog the air stripper or activated carbon, or upset the biological treatment system. An ID-221 Oil Sheen Detector can be installed in a settling tank after the separator and before the treatment system. Upon detection of oil sheen, the pump bringing water from the separator will be stopped and the alarm set off. An oil skimmer can then be turned on until the oil sheen is removed.

Monitoring of Water Discharge After Treatment

Environmental authorities allow treated water with only a few ppm of hydrocarbons to be discharged back into the groundwater or public drainage. Therefore, redundancy is important in this application. On-line ppm monitors are used for this purpose. However, the monitoring can be complemented and enhanced with Leakwise. A Leakwise ID-223 Oil Sheen Detector installed in a settling tank mounted on the discharge pipeline will set off an alarm upon detecting the oil sheen and shut the discharge valve. This will indicate to the operator that an upset in the treatment system occurred and prevent unauthorized discharge.