Dave Adler has a unique perspective on construction-trench cave-ins. He's been an underground contractor for 26 years, specializing in flood control, and he's also a lieutenant in charge of technical rescue for the Addison, Ill., fire department. In his 24 years as a firefighter, Adler has seen his share of devastating trench collapses, and is understandably zealous about promoting new rescue techniques among northern Illinois fire departments.
A technique he considers especially promising is vacuum excavation, coupled with air lances and pneumatic shoring. Depending on soil type, says Adler, pneumatically activated shoring struts can be quickly installed, with or without added debris barriers, to first form a 4-foot-wide safe zone for rescuers. Next, he says, the best practice is to use the vacuum source and the air lance (he says that Air-Spade manufactures a special rescue model) to create a pit in front of the victim. This then allows the powerful vacuum hose (usually connected to a municipal sewer-cleaning truck) to be safely positioned above the pit, away from the victim, while the rescuer carefully uses the air lance to direct debris off the victim and into the pit.
As an added precaution, says Adler, a quick-release mechanism in the vacuum hose should be mandatory. A raised hand by anyone on site should be the signal for the safety officer to immediately pull the release.
Time is the enemy during trench rescue, says Adler. The victim, perhaps already suffering injury from the force of the collapse, also may be threatened by hypothermia and by acid build-up in extremities where blood circulation is impaired. The release of these acids into the circulatory system after rescue may prove fatal.
Lieutenant Adler can be reached at AdlerAFD@aol.com.