Levee on rise as new work continues on sewer plant

Posted 10/30/14

The Warwick Sewer Authority unearthed a problem when the contractor elevating the levee started installing fiberglass sheeting designed to protect the treatment plant from the next big Pawtuxet River …

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Levee on rise as new work continues on sewer plant

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The Warwick Sewer Authority unearthed a problem when the contractor elevating the levee started installing fiberglass sheeting designed to protect the treatment plant from the next big Pawtuxet River flood.

The 25-foot long panels are to be driven 20 feet into the existing levee for a 1,800-foot section of the barrier that runs too close to treatment plant tanks and buildings to be elevated with earth.

But as hammers pounded, the sheeting cracked. It was hitting something that wasn’t shown in the original levee plans. Work stopped. Crews started digging, and it wasn’t long before they had their answer.

“They took out big boulders and we tried it again,” Janine Burke, director of the Warwick Sewer Authority, said in an interview Friday. The second and successive efforts were no more successful. The inter-locking sections of sheeting kept cracking. Evidently, when built in the mid-1980s, the contractor laid down a base of rocks that was never shown on the plans.

Burke called a halt to that portion of the levee work requiring sheeting and turned to the engineers to see what should be done at this point.

The boulders were a curveball that she could have done without.

The solution appeared to be steel sheeting that is more costly and raises issues over rusting and life expectancy.

“We’re waiting for the engineers to come back,” said plant supervisor Patrick Doyle.

Meanwhile, rows of fiberglass sheeting are neatly lined up near the worksite. They’ll have to be returned, although that has yet to be worked out, said Burke.

The sheeting is the first major crimp in the levee project since the March 2010 flood inundated the plant, causing $14 million in damages. Elevating the levee to prevent future flooding seemed like the logical thing to do, yet obtaining the Federal Emergency Management Agency funding for the job was a challenge. Initial estimates put the project at $5 million. The sewer authority was prepared to proceed with the project regardless of whether the federal money became available. It was the prudent thing to do, although it would increase the authority’s debt cost, ultimately resulting in higher user fees.

Then things turned for the better. The congressional delegation pushed for a FEMA grant, and $3.6 million was eventually approved. Then it got even better. The authority put the project out for bids and the work came in at less than the $5 million first projected. In fact, at $2.2 million, it was $700,000 less than the FEMA grant.

Burke is hopeful that, with the increased cost of using steel sheeting, the authority will be able to access the full amount of the grant that pays up to 90 percent of project costs.

“We do have a bit of a buffer,” Burke said, referring to the FEMA grant.

But until the engineering work is completed and expensed, there’s no knowing how much more the levee will end up costing. Overall, the levee is being raised 5.5 feet, which is projected to withstand a 500-year flood.

Elevating the earthen levee requires extending its base. For every foot in height, the base needs to be expanded by two feet. As all the work is being done on the plant side of the levee, the structure is encroaching on the animal shelter. At last Thursday’s meeting, the authority board approved a $22,000 change order to ensure that water running off the levee wouldn’t pool in the shelter parking lot or outside cages. A catch basin will be installed at the end of the parking lot with a drainage line connecting to the plant system.

The plant is designed so that surface water and effluent – the plant is capable of processing 7.7 million gallons of wastewater daily – gravity feeds into the river. During river flooding, which would reverse the system, the drains are shut and massive pumps take over, ensuring uninterrupted plant operations and that 21,000 residential customers linked to city sewers can still flush their toilets, do their wash and 1,400 commercial and industrial users, including hotels, the malls, the airport, manufacturers and even Kent Hospital and Community College of Rhode Island, don’t experience problems.

In March 2010, a couple of issues compounded flooding of the plant. Water flowed in from Route 95 drains, straining the plant’s pumps.

But it was the river that finally surrounded the levee and swamped the operation. Generators, settling and treatment pools, control systems, offices and even the adjoining animal shelter were submerged. At the height of floodwaters, cresting at 20.79 feet, the cap to the levee was three feet below the rapidly flowing river and 22 feet above flood stage.

Check valves and elevation prevented sewage backups throughout the system, but without anywhere for all the wastewater to go, Burke knew it was only a matter of time before the city was faced with an even larger disaster.

Mayor Scott Avedisian appealed to the public to take short showers, put off washing clothes and refrain from flushing toilets. With the retreat of floodwaters, the authority was able to quickly restore basic primary treatment with the chlorination of wastewater, but bringing everything back online would take months. Elevating the levee will prevent that from happening again, except for a flood exceeding that of 2010, which was a record.

Burke finds a silver lining to the ordeal in that plant systems have been updated with $10 million of the $14 million in costs being picked up by the intercity local trust, the city’s insurer. FEMA paid $3.9 million with the balance coming from the authority.

Furthermore, as the authority is being required to meet stricter standards for the removal of phosphorus in the treatment of wastewater, excavation for those tanks is providing material for the raising of the levees. Work on that project, costing $12 million, is in full swing. The facility should be up and operational by April 2016.

The authority is also working on the extension of sewers with a $33 million revenue bond approved by the City Council.

Design as well as some preliminary work of East Natick Phase 3, known as O’Donnell Hill, Governor Francis Farms Phase 3 and the Bayside projects is underway. In her recent quarterly report to the council, Burke said design engineer Gordon R. Archibald, Inc. is coordinating planned construction of Governor Francis Farms sewers with other utilities; that design and permitting is being completed for O’Donnell Hill; and that the authority would be meeting with the Narragansett Indian Tribe, the Rhode Island Historical Preservation & Heritage Commission, and the U.S. Environmental Protection Agency on the Bayside projects.

As a number of architectural features, including Indian burials, have been identified in the path of the Bayside projects, Burke said the authority is exploring “directional drilling” that would allow the installation of pipes without disturbing historical sites. Where possible, she said, it would be a gravity system, but for the most part she envisions a low-pressure system requiring individual grinder pumps.

The first construction of Bayside projects would be in 2017, with two additional phases beginning in 2018. Work on Governor Francis Farms and O’Donnell Hill would start next year and Northwest Gorton Pond in 2016.

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