Emergency Sewer Repair Work - Emergency Sewer Work due to Existing 36” Sewer Main Deterioration & Manhole Replacement

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MEMO To: Board of Public Works From: Leslie Biek CC: Kara Boyles, Toy Villa Date: 9/20/2020 Re: Emergency Sewer Repair work on Ironwood and Corby The Corby, Rockne & Ironwood Intersection project (Project #116-034) began in May of 2020. This LPA- funded/INDOT-approved project included pavement reconstruction, installation of a new traffic signal system, and related stormwater drainage with a cost share to the city of only 20% local dollars. Construction is complete and the intersection is fully operational today. As pavement removal was taking place in the center of the intersection of Corby and Ironwood, a sinkhole was discovered adjacent to an existing 72” manhole. Upon further investigation it was discovered that the existing 36” Ironwood combined sewer was failing with approximately 2 feet from the top half of the structure missing. This was quickly deemed an emergency project based on the need to repair the sewer main in order to prevent delays to the general contractor. Several alternatives were explored with the prime’s sub-contractor already on-site, HRP construction. Options included patching and lining the sewer as well as complete replacement of the sewer. Based on overall cost estimates, the need for bypass pumping regardless of the selected alternative, and various utility conflicts, complete replacement of the sewer main was chosen. Emergency work included replacement of two (2) 72” manholes, 250 feet of 36” sewer main, and five (4) sewer laterals. Bypass Pumping was required in order to facilitate the work. The Bypass Pumping included bypassing the 36” sanitary, 10” sanitary and the 12” forcemain on Corby. In addition, when exposing the manhole at the Corby/Ironwood intersection the contractor encountered an issue where a concrete collar had been placed around the existing 12” watermain to protect it from the sanitary manhole and 12” forcemain. This was resolved by installing shutoff valves on both sides of the existing 12"watermain (north and south side of the manhole on Ironwood) and replacing the water main as well. The work began on June 16th and was completed on July 9th. Despite 25 days of delay, the general contractor finished within the contract timeline.