Leak Detection by Groundwater Monitoring

Groundwater Monitoring

Leak detection by groundwater monitors may appear to be too late for early detection since it’s done after the groundwater started to be contaminated. However, a closer analysis of the risks of non-detection and false alarms inherent in using other methods may reveal that especially in sites with shallow groundwater, this may be the only effective detection method. An important precondition for using a groundwater monitor is that it can detect hydrocarbon seepage reliably as soon as it occurs, and without false alarms.

OIL DETECTION IN GROUNDWATER WELLS

Manual groundwater sampling, which is done periodically in some sites, does not provide an ample solution since it may not detect the seepage as soon as it occurs. Also, oil sheen displacement occurs when immersing a bailer into a monitoring well, which does not allow the detection of very small oil layers.
On-line capacitance and conductivity floating detectors are incapable of detecting hydrocarbon layers thinner than 3-4 mm (5/32 in). These sensors require extensive maintenance since dirt and hydrocarbon coating on their detection electrodes cause false alarms. Changes in water level may result in reducing their detection capability to a minimal layer of 10 mm, and re-calibration is often required.

LEAKWISE ID-221 OIL SHEEN DETECTOR AND ID-225 OIL LAYER
THICKNESS MONITOR

This is the preferred and proven solution for groundwater monitoring. By using the principle of energy absorption, the Leakwise ID-221 Oil Sheen Detector supplies the best available solution to local and remote online groundwater monitoring. The ID-221 Sensor detects hydrocarbon layers as thin as 0.3 mm
(1/8 inch) and thus provides an early alarm of hydrocarbon seepage, earlier than any manual sampling or other floating detectors. Its capability to detect small layers is maintained regardless of water table fluctuations. Dirt and coating of hydrocarbons on the detection antenna can be out calibrated without the need to clean the antenna. The ID-221 Oil Sheen Detector has a unique capability to monitor an increase in the thickness of the contaminating layer up to 25 mm and can be calibrated to give low and high alarms. The Leakwise ID-225 Oil Thickness Monitor has a 4-20 mA linear output of oil layer thickness in the range of
1-100 mm or 1-200 mm is used for monitoring heavily contaminated groundwater. Both Leakwise ID-221 and ID-225 Sensors are suitable for installation in monitoring wells with a minimum diameter of 4 inches, with unlimited depth and water table fluctuations.