Bolton, Atilana

Atilana Bolton is a Technical Project Manager within the Underground Solutions Team for Structural Technologies. She graduated from the University of Texas at Arlington with a Bachelor of Science in Civil Engineering and specializes in pipeline condition assessment and rehabilitation. She is actively involved in technical committees with DBIA and WCDA. She has her Professional Engineering license in the state of Texas. Atilana assists clients with options analysis, technical support, engineering, and specification development and review.

Titles from this speaker

Thinking Outside the Box: Innovative Emergency Repairs on Twin Outfall Relief Sewers

Abstract

A twin outfall relief sewer system for a major municipality is comprised of twin box structures approximately 11 LF in height and 10-12 LF in width, with average flows of 200-700 MGD. This sewer system is located below a military facility, making all inspections and repairs demand additional security considerations. During recent inspections of the twin outfall relief sewer system, CCTV footage showed areas of the sewer structure with extensive corrosion damage from microbial hydrogen sulfide (H2S). The damage caused by the H2S was so severe that the center wall between the twin box structures was missing for approximately 75 LF and much of the inner layer of reinforcement was also missing. The Owner's engineer performed structural analysis and determined the degraded portion of this structure was near collapse. Based on the as-found conditions and analysis performed, emergency remediation of approximately 910 LF of rectangular box structure was deemed necessary. The next step to minimize risk of collapse involved removal of the soil overburden in the region where the sewer system showed severe distress. The project team worked to develop a bypass system to reroute flows so permanent repairs could take place. Given the live flows within the structure, rehabilitation options needed to be selected prior to the bypass system being in place and the structure dewatered. This uncertainty regarding the condition of the structure required the repair system selected to be flexible to accommodate varying degrees of degradation. An innovative sewer rehabilitation technology was selected which involves installation of custom fabricated steel rings, HDPE interior protective layer, and a flowable grout to fill the space between the HDPE and the host structure. The design of the rehabilitation system can be adjusted based on as-found conditions, giving the project team the flexibility needed to move forward with repair design in parallel to installing the bypass and performing a more thorough condition assessment of the structure. This technology has a history of over 20 years of successful implementation in Japan with over 250,000 LF of successful pipeline repairs. This extended history along with extensive technical vetting allowed the project team to feel confident moving forward with a first-of-a-kind application in the United States. This paper will highlight the investigation, analysis, design, and emergent repair of this critical structure. Perspectives from the Owner, Engineer, and Contractor will be provided, along with insight on the options analysis process, and lessons learned throughout.

An inspection for DC Water in 2023 discovered significant deterioration in the East-West Outfall Relief Sewer (EWORS) between Structure 2A & Structure 105. Deterioration included loss of sections & visible damage to the top slab & walls, & extensive damage to the mid-wall between the east and west channels. Phase 1 repairs focused on stabilization of the structure & construction of a gravity open channel diversion structure. Phase 2 involved rehabilitation using the PALTEM(R) Flow-Ring System.

SpeakerBolton, Atilana

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionDon't Miss the Bypass!

Session number602

Session locationRoom 338

TopicCollection Systems, Intermediate Level

Author(s)