“So we try to manage our collections system in a way that we can capture that differentiation in flow.”

Low flow velocity also increases sedimentation, which creates problems if heavy rains occur. That creates what Mehram calls a major “slug load” — a high volume of solids — at the WRRF.

“We can go from an average loading of 300 dry tons per day of solids to 1,200 dry tons per day during a rain event,” he says.

Improving water quality

Implementation of the master plan will occur in three phases: Optimizing existing infrastructure; adapting to take advantage of opportunities as they arise and expanding pipes and wet-weather facilities to further improve water quality; and then sustaining the improved performance through continued maintenance. Many key phase-one initiatives already are underway.

Related: WinCan VX Integrates with ESRI ArcGIS

Moreover, the master plan is not just a road map for regulatory compliance. Instead, it also focuses on improving water quality.

“We want to see real tangible improvement of the quality of water in rivers,” Coffey says. “We’ve already invested more than a billion dollars in the last 25 to 30 years in combined-sewer overflow controls, including wet-weather control facilities that treat and discharge any overflow.”

In addition, the utility has established a water-quality monitoring program in which local streams and rivers get tested regularly, not just during sewer overflows. The testing will be performed with both “grab samples” and by continuous in-stream sampling.

The agency uses Suna nutrient sensors made by Sea-Bird Scientific, and NuLab nutrient sensors developed by Green Eyes.

“So over time, we’ll be able to spot trends and make operational improvements that will keep improving water quality,” Coffey says.

Related: Get the Full Picture with WinCan’s Esri ArcGIS Integration

Optimizing assets

The plan, which will be updated every five years, also focuses on optimizing existing infrastructure in order to minimize significant investments in new capital improvements. Coffey says that will help ease one of the biggest barriers to implementing most master plans: funding.

“For us, affordability is always at the forefront. We’d love to obtain more state and federal dollars, but the best thing we can do now is plan well and optimize what we’ve already invested in, which will reduce the need to build new facilities.”

For a good example of optimizing existing assets, consider the connectors, or regulators, that link smaller upstream concrete sewer lines to the Detroit River interceptor, which lies 20 to 50 feet deep and ranges from 9 to 12 feet in diameter. It collects flow from shallower sewers.

Currently those approximately 30 connections narrow where they meet the larger interceptor line, which restricts wastewater flow. But engineers are working on retrofitting those connections to make them larger, which would significantly increase flow to the WRRF and reduce untreated sewer overflows.

In fact, for a relatively small amount of money — about $15 million — compared to a more significant repair option, the utility plans to enlarge these connections so they match the diameter of the upstream sewer lines. That would reduce combined-sewer overflows by roughly 160 million gallons, Coffey says.

“That would eliminate approximately 10% of our untreated overflows from discharging into the Detroit River. It’s a project that provides the best bang for our buck.”

Two regulators have been expanded so far and the GLWA is monitoring their performance to see what kind of difference it makes.

Mindful maintenance

But the biggest operational challenge is sewer maintenance. “It’s a massive network and we have to ensure that conveyance is reliable every day,” Mehram says.

Generally speaking, a team of employees is responsible for inspecting and performing preventive maintenance in what Mehram calls the gravity system — the 195 miles of sewer pipes — as well as the system’s nine pump stations. Employees rely on a camera truck outfitted with inspection cameras built by Telespector Corp. and R.S. Technical Services, with WinCan VX sewer-inspection software.

The GLWA usually hires contractors to repair and/or upgrade its assets, he says.

GLWA recently completed a three-year effort to inspect all of its sewer lines. A key finding: A 12.5-mile-long, 9- to 16-foot-diameter section of the Detroit River interceptor was a high-priority candidate for repairs.

Contractors have been rehabbing the interceptor for about 2 1/2 years. Most of the work, expected to be completed in another year, centers on repairing or regrouting the largely brick structure, along with improvements for enhanced flow control and maintenance.

“It’s one of the bigger sewer rehab projects we’ve taken on,” Mehram says of the $48 million effort. “It’s also one of the most critical sewers marked for rehab.”

Technology-centric operation

The GLWA staff also uses sophisticated software programs to manage its numerous assets. Good examples are Work and Asset Management (WAM) software developed by Oracle, Microsoft Suite products like Power BI (Business Intelligence) and ArcGIS mapping and special analytics software from Esri.

WAM is used to track work orders and as a communication tool between management and front-line workers. “We aggressively use WAM on our vertical assets (pump stations and water resource recovery systems), while Power BI brings that data into a dashboard that allows us to clearly communicate needs to our leadership team,” Mehram says.

Employees use handheld data-collection devices manufactured by Spectra Precision/Trimble Geospatial to collect information for the ArcGIS system, which provides a good overview of where assets are located and their condition, all in graphical form.

Coffey notes that through development of the master plan, GLWA officials have learned that there’s strength in numbers.

“We can do more when we come together and remove boundaries from the equation,” she says. “Think about all the brain power from all the stakeholders that participated. This process has given birth to a whole new family of ideas.

“We’re well-connected with national associations across the industry, and we’ve never seen a master plan quite like this. Developing this plan involved an unprecedented amount of collaboration.