During a recent inspection, I had been informed by site personal of an on-going issue of intermittent sensor alarms. The location was having a difficult time determining the cause of the alarms and also meeting the monthly requirements for documentation of continuous interstitial tank monitoring. What I found was the interstitial sensor cable was being pinched by the steel 18 inch manway cover. It appears that upon installation the riser was installed at such a height that over time when the concrete tank pad settled just a little, that the wire ended up being pinched by the manway cover causing the intermittent alarms. The internal wire was found to have been partially broken under the outer jacket, while the outer jacket remained continuous. A shortening of the riser and repair of the sensor cabling corrected the issue and the site is now back in compliance.

Lorenzo DiBacco, Field Services Manager