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Upgrading the wastewater collection system

New wireless technology improves data, cuts costs

Cell phone technology – love it or hate it – is helping the Metropolitan Council’s wastewater collection facilities cut costs and increase reliability. It’s a key component of a newly upgraded data communications system, sort of a lower-cost text-messaging feature that doesn’t require your teenager to do it for you.

The new system:

• Allows staff to monitor and adjust pumping station operations remotely.
• Greatly simplifies equipment maintenance.
• Improves collection and storage of wastewater flow data.
• Increases the accuracy of the data.
• Saves about $10,000 monthly in communications technology costs.

 

Monitoring wastewater pumping stations

The new wireless communications system links 62 regional wastewater pumping stations and 195 flow meters to the regional maintenance and dispatch center in Eagan that is staffed 24/7 by Metropolitan Council Environmental Services (MCES).

The meters continuously measure the volume of wastewater coming from each of the 104 communities hooked up to the regional wastewater collection and treatment system. Volume data are sent to a central computer and used to determine how much MCES will charge each community for wastewater service.

The pumping stations move the region’s wastewater up from the valleys and over the hills before it can flow as much as possible by gravity to the treatment plants. MCES staff conduct daily operation checks and periodic maintenance, but the stations hum along on their own the majority of the time. As area manager Wally Bachtle explains, the communication link “is our eyes and ears in the off hours to tell what the stations are doing, so we can quickly figure out if there is a problem that requires us to send someone out.”

Collection of data from these facilities was first automated back in the 1970s, and for more than 30 years it was transmitted over telephone lines. With the land lines used since the 1970s heading down the road to obsolescence, newer high-speed service was needed to monitor the lift stations.

Technology cuts costs, improves process controls

Wireless cellular technology was taking off at just the right time to incorporate it into MCES’s communications upgrade, Bachtle said. Approximately 130 of the 195 flow meters utilize the wireless communication. It will cost about 90 percent less than using the old phone lines at the meters, saving about $10,000 a month while performing more reliably.

The upgraded communications system also employs standardized programmable logic controllers (PLCs) that will allow dispatch center staff to monitor more aspects of the pumping station operations and actually begin to adjust pumps, standby power generators, air handling systems and other equipment remotely. The standardized PLC components will greatly simplify maintenance and decrease the need for a widely varying spare parts inventory.

System improves flow measurement

The system will improve collection and storage of wastewater flow data, while also increasing the accuracy of the information, Bachtle said. That will help MCES more precisely determine volume figures: the monthly totals for calculating cost allocations to each city, and the peak flows that include stormwater and groundwater entering local sanitary sewers during heavy rains or snowmelts.

MCES is working closely with cities to eliminate the amounts of inflow and infiltration of these clear water sources that are deemed to be excessive. The flow volume data also helps MCES watch for regional sewer pipes and pumping stations that are nearing capacity and construct additional facilities where necessary.

In-house upgrade provides further savings

Another key to this successful upgrade was that it was done in-house, said Bill Moeller, an assistant general manager at MCES in charge of the wastewater collection system. Computer staff handled the programming and electricians did the wiring and installed the PLCs, saving an estimated $1.5 million in avoided outside contractor costs.

“Our employees built this system, so they know better than anyone how to operate and maintain it,” Moeller said. “Besides the financial and reliability benefits we’re already realizing, I think one of the real values we’ll see out of this project will be in how much easier it will be maintain over the years. It’s a state-of-the-art system, and it will be easy to replace components as we need to and as technology improves.”