Decades in the Making

Fall River’s massive CSO abatement project has made a big impact on local water quality.
Decades in the Making
CSO supervisor Alan Levrault, right, looks on as Mark Correia, left, and John Melo use the Vactor truck to suction screening debris that was captured by the CSO screen during a rain event.

Interested in Flow Control?

Get Flow Control articles, news and videos right in your inbox! Sign up now.

Flow Control + Get Alerts

The problems facing many of our older Northeastern cities are widely known — population loss, economic woes, deteriorating infrastructure.

Fall River, Mass., has had its share of hard knocks, too. Once the nation's leading textile manufacturer, the city has lost industry and population. Nonetheless, the Fall River Sewer Commission is nearing completion of a decades-long, $185 million combined sewer overflow abatement project that has already improved water quality and promises to help the city prosper in the future.

"As difficult as this has been for us," says Terry Sullivan, administrator of community utilities, "all of the public referendums required for the various phases of the project passed by a pretty good margin (around 60 percent to 40 percent). The public has understood the need to comply with regulations and improve water quality. It's a good reflection on the city and our ability to move forward."

Even the steep topography and granite bedrock have helped. A new 3-mile-long, 100-foot-deep stormwater storage tunnel needed hardly any liner because of its impervious granite walls, and the stored water drops by gravity 100 feet to the city's treatment facility, eliminating the need for pumping.

Fall River

Fall River lies on the eastern edge of Mount Hope Bay, which connects to the Atlantic Ocean, with much of the city built on steep hillsides rising 150 to 200 feet above the water's edge. Its population has declined to around 90,000 from a high of 120,000 in the 1920s, but it still ranks as the tenth largest urban center in Massachusetts.

The city's wastewater infrastructure includes one regional treatment plant and one satellite treatment facility; 179 miles of sewers (about 85 percent of them combined); 6,000 catch basins; 6,000 manholes; and 15 pumping stations.

The service area includes all of the city, as well as portions of several small abutting communities in Massachusetts and Rhode Island.

The sewer system dates back to 1857, and for many years, wastewater and stormwater was simply diverted into the bay. The first wastewater treatment plant was commissioned in 1948. A 60-inch interceptor ran along the shore of the bay, directing dry-weather flow to the treatment plant, but releasing stormwater and diluted sewage over a number of weirs to the bay when rainfall amounts became too much to handle.

The treatment plant was upgraded to secondary treatment in the early '80s, and the major pump stations were also updated.

These improvements were not enough to prevent a third-party lawsuit from the Conservation Law Foundation, however, and in 1984, the city embarked on a comprehensive, long-term CSO plan that continues today. In fact, Sullivan has spent his entire professional career at Fall River dealing with the project, which is expected to continue until 2018, when final construction is expected to be complete. It has literally been his life's work.

"Overall, our CSO project is designed to address 19 CSOs throughout our system," explains Sullivan. "To date, we've spent about $165 million of the $185 million budgeted, and managed all but three of the overflows."

Funding has come from federal grants, the Massachusetts State Revolving Loan Fund, and sizeable rate increases.

Phased approach

After the planning phase, completed in the late 1980s and costing about $10 million, Phase 1 of the construction made improvements to the Fall River regional wastewater treatment plant. Capacity was expanded from 50 to 110 mgd, and the treatment works received multiple equipment improvements to manage the increased flow. These included new Flygt pumps to transport the influent from the existing interceptor, new Vulcan bar screens, level control by Siemens, VFDs by Square D (Schneider Electric) and electrical panels by GE. In the new design, the first 50 mgd receives full secondary treatment, with any excess flow passing through the headworks, primary treatment and disinfection before it is discharged to Mount Hope Bay.

In 2007, the plant won the National Association of Clean Water Agencies' Peak Performance Silver Award, as well as the EPA's Operation and Maintenance Award for Region 1 (New England) and the Excellence Award from the Massachusetts Water Pollution Control Association.

Deep tunnel

In Phase 2, a 3-mile-long, 20-foot-diameter stormwater storage tunnel — capable of holding 38 million gallons — was bored 100 feet underground. Nine dropshaft diversion structures can allow the combined sewerage to be directed to the tunnel or to the existing interceptors as needed, Sullivan explains. The tunnel acts as both a dry-weather interceptor and a CSO conveyance/storage tunnel. Water stored in the tunnel flows by gravity to the treatment plant.

The structure, drilled through the extremely hard granite bedrock that underlies Fall River, cost $78 million and took five years to complete. The rock proved advantageous, however, in that the interior surfaces of the tunnel are so smooth and impermeable, no liner was required except for one small area — a cost savings of $15 million to $20 million, Sullivan estimates. A ventilation shaft at the end of the tunnel allows for positive displacement of the air.

While the drilling of the deep tunnel caused much less surface disruption than sewer separation, some homeowners noticed as the 700-foot-long tunnel boring machine, manufactured by The Robbins Company, ate its way through the rock beneath their property. The machine had a 20-foot-diameter cutting head with dozens of "cutters" that pulverized the rock into gravel-sized pieces. These pieces were diverted to conveyors and ultimately to railcars that carried the rock to the surface for re-use as gravel.

"I got several calls from residents telling me they noticed something different in their basements, and wondered if it was their boiler," Sullivan says.

The tunnel and the first four dropshafts became operational in 2005. "On a normal day-to-day basis, we handle about 20 million gallons at the treatment plant," says Sullivan. "During heavy rains, we can manage up to 110 million gallons, and beyond that, we can store up to 38 million gallons in the tunnel. We're designed for the maximum three-month storm, which we classify as 1.76 inches of rain in any 12-hour period."

Also in the second phase, two of the utility's largest pump stations were upgraded — Central Street (15 mgd) and Cove Street (12 mgd), which was equipped with self-cleaning rotating drum screens (Vulcan) and disinfection capabilities to create an independent satellite treatment station. Disinfection is achieved through the use of liquid chlorine. The dry-weather pumps at both stations and the wet-weather pumps at Cove Street were all supplied by Flygt. The emergency generators were made by Caterpillar, and the rag washer at Central Street was made by Waste Tech (Kusters Water).

Sullivan says the satellite treatment system — started up in 2009 — is working very well.

"Before, dry-weather flow would come through the Cove Street station and pass to the treatment plant, but during wet weather, excess flow would go over the weir and into the river," he explains. Now, through the addition of large impeller pumps, smaller feed pumps, and the fine screen and chlorination steps, up to 54 mgd of storm flow is treated before it's discharged to the outfall. Sullivan explains that the chlorine residual dissipates significantly before the treated water reaches the discharge point.

These steps have effectively addressed 16 of the 19 CSO points in the Fall River system. Sullivan says the three remaining CSOs are being remedied now, with satellite treatment planned for Alton Street, City Pier and President Avenue. "Right now, we're reanalyzing Alton Street and City Pier, comparing the cost of separation against screening and disinfection," explains Sullivan.

The final phase of the Fall River project is scheduled to take place in 2015-2018, and will include additional sewer separation and green solutions to stormwater in the south end of the collections system.

Costs and benefits

A national news story last fall reported significant water and wastewater rate increases around the United States. It didn't include Fall River in its examples, but it could have. "Our CSO project has had a severe impact on our customers," says Sullivan. "The rate increases are up as much as 400 percent," he says, explaining that the sewer user fee was at 96 cents per 100 cubic feet before the project, and is now $4.09. In addition, the city has imposed a stormwater fee on all customers — smaller for residential users, who pay $140 annually, and larger for developments like shopping malls with large parking lots, which pay $140 per 2,800 square feet of impervious surface on their property.

"We've had no choice," Sullivan says, pointing out that the city's debt service on the water and wastewater improvements is significant in and of itself. "Forty-five percent of our sewer and stormwater budget is for debt service, and 33 percent of our water budget is for debt service."

In terms of dollars and cents, the average water-sewer bill in Fall River has risen from about $150 a year to around $900 a year.

The loss of manufacturing added to the expense, because the mills were large-volume water users, paying a lot in water and sewer fees.

Still, Sullivan points out that the public has supported all three referenda on the CSO project. "I think the public has understood the need to comply with the lawsuit and improve the water quality in the bay," he says. "We're replacing sewers and water mains from the 1800s. We've done our best to minimize the rate increases. We're not alone, and it's not a luxury for us, but it's a good reflection on our city and our willingness to move forward. From a water quality perspective, these are good goals to have."

Results

Perhaps the best thing that's happened is the improvement in water quality; it's significant and visible. "I frequently stroll along the walkway that lines the bay, and I can see the difference," says Sullivan. "Twenty years ago, you probably couldn't see more than 3 inches down into the water. Today, you can see 6 to 10 feet. It's crystal clear."

The shoreline itself is a pleasure to look at as well, with Veteran's Memorial Bicentennial Park and a small replica of the Iwo Jima U.S. Marine Corps monument. Sullivan says the old manufacturing area is being improved, with restaurants, tennis courts and shops along the waterfront.

And clean water has more than an aesthetic value. Sullivan explains that because of fecal coliform counts, former shellfishing areas in the bay were shut down many years ago. But now they're coming back. "Both were opened conditionally a year or two ago," he says. "The state Department of Fisheries is extremely pleased with the water quality improvements here."



Discussion

Comments on this site are submitted by users and are not endorsed by nor do they reflect the views or opinions of COLE Publishing, Inc. Comments are moderated before being posted.