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Diver down: Divers help water district keep storage tanks clean

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By Vicky Gits

It’s not exactly a trip to Tahiti, but divers venturing into the various underground reservoirs serving the Evergreen Metro District help keep the water system in good shape.

The week of May 9-13, the district hosted three dive professionals from Liquivision Technology Inc. of Klamath Falls, Ore., for a tour of the area’s many tanks.  
They come to rid the district’s storage system of an unwanted quarter-inch layer of harmless iron and manganese particles on the tank bottoms. They also check the walls for any leaks or cracks in the concrete and make sure the intake and effluent pipes are solid and that the tank is structurally sound.
The minerals are abundant in the lake water from which the district gets its water supply, and tend to settle in the water mains as well. That’s why, during the summers, EMD flushes the water mains in different areas, completing the entire distribution system (18,000 feet) in three years.
With 10 tanks to clean, the divers clean two each day and take five days to complete the assignment, which cost the district $15,000.  
On Tuesday afternoon May 9, the Liquivision divers set up shop at the Greenwood tank, on Fairway Drive near Buffalo Park Road, one of the oldest storage units in the Evergreen Metro District.
The tank is underground and is covered by a thick concrete slab, with access through a metal hatch on top. Two other tanks had been cleaned earlier in the day.
The Greenwood tank holds about 100,000 gallons and is about 10 feet deep, said Glen Gross, lead water plant operator for EMD, who was supervising activities on the ground.  
Without the divers, Gross said, the district would have to drain the reservoirs and suspend service to the surrounding area for as much as two or three days.
Cleaning has no effect on tap water, but draining the tanks would cause “pressure issues,” said Garry Jeffrey, water plant manager. In addition, it could affect firefighting abilities.

Suiting up for the dive
The diving equipment doesn’t look that comfortable on Case Sigfridson, the dive team leader.  Layer one is jeans and a T-shirt. Next comes a stiff, ill-fitting and bulky red rubber suit. On top of which goes a 40-pound weight belt.
Equipped with a camera and lighting devices, the blue, heavy-duty diving helmet trimmed in chrome is equally weighty and resembles an oversized bowling ball. It attaches to the suit like a shuttle docking with the space station.
Then comes a bleach-solution shower over every inch of the helmet and the suit, which is necessary since the tank in question is full of drinking water. A spare tank of oxygen is strapped to the diver’s back in case something happens to the main airflow cable attached to the helmet.
Every move the diver makes under water is monitored on a TV screen by technician Ryan Torgerson, who is inside a truck parked about 50 feet away from the underground tank. Torgerson also works as a dive professional.
Cleaning a relatively small tank like the Greenwood will take about two and a half hours.
Sigfridson has been cleaning tanks for about five years and still loves to go diving as a hobby. His favorite places are anywhere in the South Pacific or the Great Barrier Reef in Australia.
Tony Beam was a heating and air-conditioning mechanic for 10 years. He got into tank diving as a result of his interest in water-skiing and whitewater rafting.  
The divers go on the road for about a month at a time and work year-round across the country.  
EMD has 10 tanks across the water district. One of the largest is the Troutdale tank, which contains 2 million gallons. The American Water Works Association recommends cleaning tanks every five years or so. The district first began using divers in 1996.

Contact Vicky Gits at vicky@evergreenco.com or 303-350-1042.