Hydraulics & Waterways

Oral

397741 - Surge Modeling using TAP Informs Rehabilitation and O&M Decisions on the 60 Mile-Long Potomac Interceptor System

Monday, June 4
4:00 PM - 5:30 PM
Location: Regency Room
Co-Authors: Srinivasa Gadiparthi, 5000 Overlook Avenue SW | Washington, DC 20032 – DC Water; Essey Woldemariam, 5000 Overlook Avenue SW | Washington, DC 20032 – DC Water; Chris Ranck, 150 W Market Street, Suite 728 | Indianapolis, IN 46204 – Arcadis

The Potomac Interceptor (PI) system comprises three sewers totaling approximately 60 linear miles. These sewers convey flows across Maryland, Virginia, and the District of Columbia to the Potomac and Rock Creek Pumping Stations. Following major rain events in April and May 2014, DC Water embarked on an effort to incorporate these interceptors into one comprehensive sewer model and utilize that model to inform decision making on a variety of rehabilitation and O&M improvement initiatives. A portion of this model was built into the Transient Analysis Program (TAP) specifically to conduct surge modeling to gain a better understanding of possible air movement and transients within the PI system. As such, TAP was post-processed for forward air induction, air pocket migration, and air pocket pressurization.

The surge modeling conducted utilizing TAP indicated the likelihood that entrapped air contributed to the weakening of two structures that connect the Upper Potomac Interceptor (UPI) and the Upper Potomac Interceptor Relief Sewer (UPIRS) along a nearby popular biking and walking trail. TAP modeling was also utilized to support the rehabilitation design of the upstream structure connecting the UPI and the UPIRS. Results indicated that the capacity exceedance that occurred during the April 2014 rain event was likely due to accumulated sediment in the UPIRS, operational challenges experienced during the event, and trapped air pockets in the UPIRS. Additionally, model results determined that the recommended solution to mitigate future exceedances along the PI system included preventative maintenance and preparing the UPIRS to operate under pressurized conditions.

Jennifer Howells, PE, CDT, ENV SP

Staff Water Engineer
Arcadis

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397741 - Surge Modeling using TAP Informs Rehabilitation and O&M Decisions on the 60 Mile-Long Potomac Interceptor System



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