Emergency Sewer Repair - GE Marshall - Sample Street Sewer Repair

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INTER -OFFICE MEMORANDUM DEPARTMENT OF PUBLIC WORKS DIVISION OF ENGINEERING AVVAQVL u H-,Ard of PoWic TO: Linda M. Martin, Clerk Board of Public Works FROM• Sue Ellen Doudrick SUBJECT: Sample Street Emergency Sewer Repair Projec 6 DATE: July 23, 2019 ✓".°", An emergency repair was performed to a sewer along the north side of Sample Street near Arnold Street and Central Services. A cave in of the brick, egg -shaped combined sewer on Sample Street, between Chapin and Arnold, warranted an emergency sewer repair. The Sewer Department investigated the sewer once a sinkhole started forming in Sample Street and backups upstream of the cave-in were occurring. Sewer department could not open the sewer by vactoring in the morning and afternoon of 6/12. Video inspection was not possible upstream of the cave in due to water levels. On 6/13 and with rain forecasted 6/14-6/15, Sewer Department asked R&R Visual to come out and inspect line to help. R&R concluded the brick sewer was in bad shape after their vactoring and inspection. The need for contractor expertise was required due to the sewer's size, shape, depth, unknown extent of collapse, and likelihood that any excavation work to perform a spot repair would likely subject the existing sewer to potential future damage or failure. On 6/14, the project was approved as an emergency repair. Three contractors were contacted on 6/14, the only contractor available and responsive to start work immediately was GE Marshall. Contractor started investigative work on 6/17 and mobilized traffic controls on 6/15. Description of work: Several repair options, including a spot repair and replacement of the damaged portion of the brick sewer; a manhole installation at the cave in location and a tie into the existing sewer; a doghouse manhole installation downstream of the cave in and a manhole replacement upstream of the surrounding cave in location, were considered to reduce costs prior to the investigation on 6/17. Investigation included excavating down to sewer and assessing the damage. Following investigations, it was concluded that vibrations during construction and the sewer's overall poor condition age that full replacement the sewer from manhole to manhole was needed to avoid risk of failure in the near future. Lining or replacement of the connecting manholes was also required. During construction, a number of issues arose. Major traffic control between Chapin and Arnold restricted EB traffic to only one lane. Upon excavation, a portion (north side of the street) was found to be brick overlayed with asphalt along the curb line. This condition made milling and asphalt replacement in the trench challenging. Additionally, there were sewer taps, an incorrectly marked 8" water main, a 24" water line crossing with casing crossing less than 18" over the sewer, and an unmarked abandoned conduit (not provided by utilities). During pipe \\COSB-FS 1\Share\Public Works\Proj ects\Proj ects by Year\2019 Projects\119-060 Sample Street Emergency Sewer Repair\4 - Construction\I - Agenda Requests and Change Orders\Sample St. Emergency Repair_rev.doc