"In our line of work tech support is really important." Michael Trent is an Operator II at the Tri Cities Waste Water Treatment Plant in Oregon City, Oregon. He continues, "A lot of people sell you things. And when you run into some unique problems, they say they can't help you. Columbia Weather Systems was able to offer solutions."
A Problem and a Solution
Clackamas County Department of Water Environment Services called on CWS when their previous weather station was having problems. "The last weather station that we had quit on us and nobody knew quite how to fix it," Trent explains. "I called the original company and they were located in California. They wanted $2000 just for someone to come up and take a look at it and tell us what we needed."
Instead, the county purchased a Capricorn 2000 weather station from Columbia Weather Systems. "I call it an elegant solution to my problem," Trent says. "They've taken a real complex thing and made it fairly simple to set up. That's what I like about it."
Waste Water Treatment
The TriCities plant treats sewage from Gladstone, Oregon City, and West Linn, Oregon. They've recently added a diversion from the Clackamas area. Volume runs as low as 3 million gallons a day during the summer and averages 10-12 million gallons per day in the winter. "We've had peak flows as high as 35-40 million gallons because of the rain," Trent says.
Sewage is processed through screens, digestors and aeration basins. Sludge from the digestors is hauled away for application on grass and hay fields. ("Nothing for human consumption," Trent confirms.) Effluent is chlorinated and dechlorinated before being dumped in the Willamette River. Every aspect is carefully regulated by the Department of Environmental Quality (DEQ). "We're supposed to have minimal or no impact on the river. It looks like we don't have any impact, but we're having a study done to make sure," Trent adds.
Rainfall Data Aids Operations
Rainfall is the most important weather parameter for treatment plant operations. They use rainfall data to anticipate increased flows and modify the system to increase capacity. "We keep track of the rainfall and we know if it's been raining for so long the ground reaches a saturation point That means that there will be more infiltration into the pipes and increase our flows. We prepare for that using rainfall data and we modify the system so we don't lose solids out," Trent says.
Additionally, he says, "We use rainfall for the truck drivers who haul biosolids from our treatment plants to the farmer's fields to determine whether they can haul that day or not. If we get more than an inch of rain in a 24-hour period, they can't put any biosolids on the fields. That's a DEQ rule."
Rainfall data is also used by engineers upgrading the plant and infrastructure. "The design engineers use rainfall to see how tight our system is and what goes on in relation to rain - how high our flows go up," Trent explains.
Wind Direction Important
"The other critical piece is wind direction," he adds. "It's real important to know wind direction because we use chlorine. If we ever had a chlorine leak and we had to report it, the first thing the agency would say is 'What's your wind direction?'"
Trent admits that the potential problem is miniscule. The chlorine is contained in a building and a leak would set off alarms and a scrubber system. It would probably be contained before it got anywhere, he says, but the risk is there. "You can't say it's never going to happen. If you do, you end up eating your words," he concludes.
Trent installed the Capricorn system with the assistance of Randy Conover, automation technician. "I am really impressed with their installation," says Nader Khoury, president of CWS. The control module is mounted outside in a weatherproof enclosure and connected through a programmable logic controller (PLC) to the facility's computer system.
Customized Wonder Ware™ software integrates the Capricorn data into the plant's operating system. Daily monitoring reports are compiled and submitted monthly to DEQ.