Spiraling Downhill: The Study and Design of a Vertical Drop Shaft Complete with Vortex Units and Replacement of an Existing Combined Sewer Interceptor

摘要

The City of Richmond, Virginia, is faced with a unique challenge of determining a permanent solution to address structurally damaged portions of Chimborazo Interceptor Sewer residing within and near a steep hillside that is prone to failure. Located adjacent to Chimborazo National Park, an unconventional design approach had to be developed to abandon the original brick step combined sewer. This paper will highlight the field investigation work, flow monitoring, hydraulic modeling and analysis, equipment evaluation, and coordination efforts that went into the proposed design of this replacement sewer. The design for Phase 1 is complete and is anticipated to bid fall 2018. It features a flow diversion chamber to separate dry and wet weather flows, a 100-foot drop shaft with two vortex flow insert units, and 800-feet of 60-inch sewer replacement. The paper also discusses recommended Phase 2 work, which includes sewer repair and realignment downstream of Chimborazo Hill.