Welcome to our inaugural 3 Rivers Proud newsletter, where we hope to engage, educate and perhaps entertain you. Here, you’ll learn more about how ALCOSAN, on a daily basis, provides environmentally conscious wastewater treatment for 83 municipalities in Allegheny County. Along the way, you may discover just how ALCOSAN manages to treat all that dirty water.

You’ll get a peek into the journey ahead as we realize the Clean Water Plan and satisfy our Modified Consent Decree commitments. We will be sure to highlight how we accomplish the following:

  • Prevent excess water from entering the sewer system.
  • Increase use of adaptive water technologies and green management.
  • Work with municipalities to assume ownership of sewers.
  • Expand ALCOSAN’s wastewater treatment plant.

We’re honored that you’ve connected with us to help the region protect the community’s health, and to be wise stewards of our public and natural resources.

Here’s to remaining 3 Rivers Proud!

Arletta Scott Williams
Executive Director


Everyone flushed. You washed this morning’s dishes. And it’s Pittsburgh, so it rained a few minutes ago and the kids are racing anything that floats down the street’s gutters, before it topples into the nearest storm drain.

But do you know where it all goes from there? Through a brief four-part story, we’ll follow a dirty-to-clean water journey, from your place to ours. Dirty water that reaches ALCOSAN is processed through two paths: liquids and solids. Below is the first part of the liquid journey:

Gravity and pumps transport dirty water through a neighborhood’s sewer infrastructure (not owned by ALCOSAN) and then into ALCOSAN’s large interceptor lines, which terminate at our low-elevation wastewater treatment plant on Pittsburgh’s Northside.

This sewer pipe is large enough to hold a classic car! Allegheny County Sanitary Authority (ALCOSAN) began operation in 1959. Dirty water from municipal customers’ homes and businesses travel through neighborhood sewer pipes, then merge into large interceptor sewers. The wastewater ultimately lands at the Northside-based wastewater treatment plant.

An average of 215 million gallons of wastewater enter the plant’s wet well each day, and sometimes more when we have heavy rain or snowmelt. The wet well measures 40 feet in diameter and reaches about 150 feet below ground. At any given time, the well accumulates more than 580,000 gallons of circulating, dirty water.

Six huge pumps use 12,000 HP to move the dirty water to above ground level, allowing the liquid to move in a controlled, downward treatment journey throughout the remainder of the plant.

ALCOSAN’s huge wet well receives 215 million gallons of wastewater daily. It’s then primed for initial treatment with the help of the station’s six massive—and colorful–pumps.

The first step removes large solids and grit in the plant’s headworks area. Here, dirty liquid is screened by racks with bars spaced about three-quarters of an inch apart. Often Styrofoam, rags, leaves, and an occasional dollar bill are screened. You can use your imagination for what else gets strained out at this stage!

The large debris is regularly raked clear, with the resulting trash compacted for landfill. The bars capture up to 100 tons of large debris every year. Overall, water stays in this bar screen area for a brief four minutes before moving to the next stop.

Yuck! Trash, plastics, organic material, and many unidentifiable bits flow through our sewers, mixed with the wastewater that ALCOSAN treats. Such debris runs through immense screens, and is dried and readied for landfill.

The water flows on through one of six grit channels. Grit here often includes storm run-off from roads, like asphalt cinders, pebbles and sand. These aerated chambers measure 20 feet by 60 feet, and detain approximately 125,000 gallons of water for nearly four minutes at a time. The aeration helps to settle the heavy inorganic material to the bottom of the tank, where it is scraped and collected for removal. The lighter, lingering organic particles remain suspended in the water for the next stage. Just how much grit is there? Annually, 1,300 tons!

Wondering where the inside of a pothole disappears to? Here’s a clue: annually 1,300 tons of grit – sand, rocks and asphalt chunks – sweep through our sewer systems, and are filtered from wastewater at ALCOSAN’s treatment plant.

Next, a slow-down begins, as slightly cleaner water enters into one of nine primary sedimentation units. Ever smaller particles settle to the bottom of this tank. These tanks measure 280 feet in length, 15 feet deep and 67 feet wide. Accumulated scum and grease that traveled the sewers float to the top and are skimmed away with automated paddles.

After large debris is removed from wastewater, ALCOSAN slows the flow to capture grease and scum from the top, and small particles that settled to the tank’s bottom.

For now, we’ll ask you to hold the thought of two million gallons of dirty water sitting there for two hours, settling, and preparing for bugs? Yes, tune in to the next issue to learn how the wastewater continues its liquid journey, from your place to ours, and is aided by the intentional addition of helpful bugs!


May was a very exciting and active month for ALCOSAN and its Modified Consent Decree, as the legal process came to an end with approval by the United States District Court for the Western District of Pennsylvania.  The Modified Consent Decree is the legal document that informs ALCOSAN’s Clean Water Plan, the blueprint for reducing seven billion gallons of overflows from flowing into local rivers and streams.

ALCOSAN has been involved in negotiations with the United States Department of Justice, the United States Environmental Protection Agency, the Pennsylvania Department of Environmental Protection, and the Allegheny County Health Department to come into compliance with the Clean Water Act (the Water Infrastructure Improvement Act).  The Act states that the Authority must improve the water quality of our rivers and streams by reducing combined sewer overflows and eliminating sanitary sewer overflows.

The Modified Consent Decree (1) allows ALCOSAN to continue forward with its Clean Water Plan, a blueprint for reducing seven billion gallons of overflows from flowing into local rivers and streams, (2) extends time frames in which ALCOSAN must implement its Clean Water Plan, and (3) allows ALCOSAN to propose future amendments to the Clean Water Plan, which might include replacing some proposed control technologies with green infrastructure controls. This Modified Consent Decree replaces the current Consent Decree that was entered on January 24, 2008.

To reach the Consent Decree goals, the Clean Water Plan will focus on four key areas:

  • Preventing excess water from entering the sewer system

This involves use of the latest technology including green infrastructure such as bioswales and rain gardens; lining and repairing pipes to prevent groundwater from seeping into the system; diverting clean streams so they do not flow directly into sewers; and sewer separation projects. To advance this effort, ALCOSAN established Green Revitalization of Our Waterways (GROW), a multi-year, multi-million-dollar grant program that funds projects that municipalities and sewer authorities might not be able to afford otherwise.

  • Increasing adaptive management and conveyance capacity

ALCOSAN will use adaptive management and base long-term planning on data from green infrastructure, flow-reduction projects, and the latest technology. This provision in the Modified Consent Decree demonstrates the willingness of the parties to the order to consider the use of green infrastructure and other flow-reduction projects in lieu of gray infrastructure where it can be shown to be as impactful in reducing overflows.  Under the Modified Consent Decree, ALCOSAN will also expand its conveyance system by adding pipes, diversion structures and tunnels.

  • Regionalizing multi-municipal sewers

ALCOSAN is making a good faith effort to assume ownership of certain multi-municipal trunk sewers and related facilities. ALCOSAN has conducted closed-circuit television inspections of these sewers, determined what repairs and improvements are necessary, and is now in the process of working with the municipalities to transfer ownership and make the necessary repairs. With the anticipated addition of more than 200 miles of sewer infrastructure as ALCOSAN’s responsibility, the system will be more efficient and seamless and it will reduce some of the burden on municipalities.

  • Expanding the wastewater treatment plant

The current capacity of 250 million gallons per day (mgd) makes ALCOSAN the largest wastewater treatment system in the region, but greater capacity is needed. The main pump station already has been upgraded and a new vehicle maintenance garage has been built outside the plant gates, making room to expand the treatment operation.  ALCOSAN will expand wet weather treatment capacity of the plant from 250 mgd to 480 mgd and wet weather headworks and disinfection capacity to 600 mgd.

ALCOSAN first entered into a consent decree in 2008 and completed development of a plan to address wet weather overflows in 2012. Although comprehensive, the public challenged ALCOSAN to make the plan more affordable for ratepayers, yet flexible enough to take advantage of advances in the field of green stormwater and wastewater management. In order to meet those requests, further negotiations were necessary and occurred.

For more information about the Authority’s Clean Water Plan, please visit www.alcosan.org/our-plan.


Did you know that besides providing environmentally conscious wastewater treatment to our customers in Allegheny County, ALCOSAN is also helping engage local students with opportunities for internships and job shadowing at the wastewater treatment plant on Pittsburgh’s Northside?

Our programs offer individual as well as team building skills that allow students to gain hands-on experience in a diverse work environment. Since 2015, a total of 27 students have been exposed to every division of ALCOSAN’s organization, working alongside Authority employees in areas such as Operations, Engineering, Mechanical Maintenance, Purchasing, and Customer Service and Billing, as examples. Students who have held these internships have majored in a variety of fields; such as nuclear engineering, environmental sciences, biochemistry and molecular biology, civil engineering, business management, communications and electrical trades.

ALCOSAN’s Scholastic Outreach and Education department accepts internship applications for fall, spring and summer semesters from students who reside within ALCOSAN’s service area and meet the following requirements:

  • High school students in grades 10-12 (including recent high school graduates)
  • College students in their sophomore through senior year
  • Post-graduate students
  • College graduates who graduated within 12 months of requesting the internship

For more information on the programs and how to apply, please visit https://www.alcosan.org/educational-activities/internships-wave-program.


It’s time for you to get in on the fun with ALCOSAN’s 2020 Summer Sweepstakes, which runs August 3-September 12. Each week you can become eligible to win prizes by participating in a few simple activities at 3RiversProud.com/sweeps. In the process, you will also learn a little more about how ALCOSAN is working to improve the water quality of our region’s rivers and streams. New this year, participants will have the opportunity to earn an extra entry each week. Be sure to check out ALCOSAN’s Facebook page to learn how!

A  winner will be selected on every Monday from the entries submitted during the previous week. There are six prizes up for grabs:

  1. Giant Swag: Get a little extra “super” for your market trip with a $50 Giant Eagle gift card and some swag from ALCOSAN and KDKA.
  2. Sandwiches and Sights: Start with some famously delicious sandwiches using a $50 gift card from Primanti Bros. Then take in the sights with two (2) round trip incline tickets as well as ALCOSAN swag.
  3. Soarin’ Style: Upgrade your style thanks to a $75 gift card from American Eagle Outfitters as well as some swag from ALCOSAN.
  4. Spanish Seafood Supper: Get ready for a special night out with a $100 Mallorca gift card and swag from ALCOSAN.
  5. Spa and Shoes: Relax your cares away with $100 Sewickley Spa gift card. Then hit the pavement with a $50 gift card from Little’s and some ALCOSAN swag.
  6. Family Feast: Take your taste buds to Mt. Washington with a $150 gift card to LeMont. And we’ll give you an ALCOSAN swag bag for later!

Winners will be announced on 3RiversProud.com/sweeps. You can also watch for the results on ALCOSAN’s Facebook, Twitter and Instagram pages. Good luck and we hope you enjoy ALCOSAN’s 2020 Summer Sweepstakes.

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