In the continuing search for the source of the Mill Creek “mystery pipe,” two more houses in Ericksen’s Addition will get dye-tested Wednesday.
The mystery pipe is dumping extremely high levels of E. coli bacteria into Mill Creek, levels high enough to exceed “acute” status even 1.8 miles downstream, at the Second Street Bridge.
The E. coli levels at the pipe itself are so high they exceed the measuring capability of the test. E. coli is an indicator of fecal contamination, or human waste.
The city has been hunting for the source of the pipe for nearly two years, since August 2012. They know the pipe goes under a house on Wright Street, and then goes beneath the street itself, but all tracking efforts have stalled at a point about five feet into the roadway.
The dye tests, which will be the fifth and sixthconducted by the city of The Dalles, involve flushing dye down all fixtures in a house, then closely watching several possible outfall points to see if the dye appears.
“The only reason we’re doing these two now is we don’t have them marked on our map as to where their tap is connected, so we’re just going to double-check them just to make sure,” said Steve Byers, wastewater collections manager for the city of The Dalles.
Those points will include the mystery pipe itself, jutting from the creek bank behind a house in the 2400 block of Wright Street, plus the nearest access points to the storm drain and the sewer drain, Byers said.
The city is testing a house on 23rd Street and one on Wright Street.
The city put door hangers on the two doors notifying the owners of their plans, and both have communicated their willingness to allow the testing Wednesday morning.
Once the dye is flushed, three or four crew will simply stand over their respective portals and shine a flashlight into them — or reflect sunlight off a mirror — and keep an eye out for the dye, Byers said.
“The sanitary sewer main is where we want it to be and there’s also the storm main that runs down the street, so we’ll verify that it does not go there and we’ll also stand at the mystery pipe,” Byers said.
“If everything’s working the way it’s supposed to, the water is supposed to be traveling two feet per second once it leaves the house,” Byers said.
But, pipes can have dips in them too, slowing progress. He’s waited an hour for water to travel 150 feet before.
John Zalaznik, environmental health specialist for the North Central Public Health District, said his agency isn’t yet planning on doing any dye testing.
It doesn’t have the dedicated funds to do so, he said. The bulk of its money is earmarked for specific programs and can’t be diverted elsewhere. If it does do testing, the health district will seek to do so in partnership with the Oregon Department of Environmental Quality, he said.
The only candidate homes for dye-testing outside city limits are among a small group of homes on Sunset Valley Drive, behind a row of homes on the east side of Mill Creek Road that are in city limits.
But those homes are 400 to 500 yards from Mill Creek, and Zalaznik and others doubt the pipe — which probably dates from the 1950s — would’ve been laid that far to carry away waste. (The Chronicle incorrectly stated in its first story that he estimated the homes were 400 to 500 feet from the pipe.)