A Revolutionary City’s Multi-Faceted Emergency Repair Under the Governor’s Avenue

The City of Revere, Massachusetts is located eight (8) kilometers (five (5) miles) north of the City of Boston and is home to a population of approximately 54,000 in a land area of 26 square kilometers (10 square miles). In 2010, the City of Revere entered into a Consent Decree with the U.S. Department of Justice for violations of the Clean Water Act. In late August 2013, as a result of the compliance requirement of the Consent Decree which requires the removal of infiltration and inflow (I/I) to eliminate sanitary sewer overflows (SSOs), a contractor working for the City was performing routine cleaning and closed circuit television (CCTV) inspection of a 45.7 cm (18”), vitrified clay sanitary sewer pipe in Winthrop Avenue in preparation for comprehensive rehabilitation that included cured-in-place pipe (CIPP) lining, service lateral connection lining, and manhole lining. During the CCTV inspection and cleaning, ahead of the planned rehabilitation work, the 100-year old, vitrified clay sewer pipe which handles 30% of the City’s total sanitary flow, an estimated 8.7 million cubic meters (2.3 million gallons) daily, experienced catastrophic failure.Winthrop Avenue, also called the Governor’s Avenue after John Winthrop, one of the founders of the Massachusetts Bay Colony and former governor from 1629-1641, is located just outside the heart of downtown Revere, on a very busy roadway that carries commuters and regular City bus traffic from downtown to the intersection of Revere Beach Parkway, a thoroughfare that connects Revere to both Boston and Cambridge. The rigorous cleaning, coupled with the fragile condition of the aging pipe, resulted in a collapse of the 6 meter (20 feet) deep conduit. The pipes' significance in the collection system required immediate set-up of temporary bypass pumping. The bypass was operated 24-hours a day by City Public Works staff. Alternatives were analyzed to determine the best approach to repair the pipe quickly and easily while minimizing disruption to the community.To complicate an already difficult situation, above the 6 meter (20 feet) deep collapse were two large diameter (40.6 cm and 61 cm) (16" and 24") water mains owned and operated by the Massachusetts Water Resources Authority (MWRA). The MWRA indicated that any work would require the City to mitigate disruption to and insure the integrity of their two large water mains that traverse above the pipe collapse. The two MWRA water pipes are transmission mains, and together with a third 25.4 cm (10”) parallel water pipe (which is located on the other side of the street and therefore did not interfere with the proposed work) provide 50% of the total flow to the City of Revere (7,230 cubic meters/day) (1.91 MGD), all of the flow to the neighboring Town of Winthrop (4,656 cubic meters/day) (1.23 MGD), all of the flow to the regional wastewater treatment plant at Deer Island (4,732 cubic meters/day) (1.25 MGD), and flow to the high service elevations in East Boston (795 cubic meters/day) (0.21 MGD). Therefore, the total average daily supply conveyed by these three pipes is 17,413 liters (4.6 million gallons), serving a population of approximately 100,000. Based on the significance of these water mains, the MWRA required redundancy; such that two water mains needed to remain in service during the sewer repair work. Therefore, the City faced a major water project in addition to the emergency sewer repair job.In addition to repairing the collapse, the City also needed to ensure that adjacent pipe reaches and sewer infrastructure maintained their structural integrity, to prevent subsequent collapses during construction or in the future. Because of this, the City looked to try to address the long term performance upgrades while simultaneously executing the needed repair work. Since bypass pumping would be needed regardless of the chosen approach, there was a hope to have it serve two purposes. Rather than bypass once for the repair and then again in the future to execute the upgrades, it was decided that performing the needed repair of the collapsed pipe would be done in conjunction with trenchless technologies needed to rehabilitate the aging infrastructure. Alternatives evaluated included pipe bursting, pipe jacking, directional drilling, CIPP lining, direct bury, etc., with particular attention paid to the requirements imposed by MWRA to protect their critical water mains. Ultimately a combination of repair methods were cobbled together to comprehensively rehabilitate approximately 244 meters (800 feet) of sewer infrastructure along Winthrop Avenue including spot replacement of sewer, CIPP lining, service lateral lining, manhole rehabilitation and grouting. This paper will detail the significant challenges faced by engineers and contractors during the eight month project including heavy traffic, extreme weather and timely funding, and will describe how a combination of trenchless technologies and direct bury techniques, along with complicated bypass pumping operations for both water and sewer, were used to rehabilitate the century-old infrastructure.