Consolidation and Relief Sewer at East Franklin 140th Street

The East 140th Street Consolidation and Relief Sewer (CRS) is a part of Control Measure No. 6, Euclid Creek/Dugway Storage Tunnel System, identified in Appendix 1 of the Northeast Ohio Regional Sewer District (NEORSD) Consent Decree. DLZ performed pre-design studies, geotechnical investigations, survey, flow monitoring, hydraulic flow modeling, sewer and green infrastructure design, and construction administration. The project consists of approximately 13,900 feet of consolidation sewer in the tunnel, 330 feet of hand-mined tunnel, 6,800 feet of sanitary connection sewers, and modifications to 29 regulators, three green infrastructure stormwater detention basins and over 11,850 feet of associated stormwater collection system components. With a focus on incorporating green infrastructure, DLZ performed the following major tasks for the project:

Refining the Existing Hydrologic/Hydraulic Model

This work included converting the long-term control plan model to an InfoWorks platform; checking and refining catchment boundaries; re-establishing sanitary sewer flow conditions for each sewer shed; revising the impervious area estimates within each drainage catchment; quantifying uncertainty in stormwater flow estimates; calibrating the model by analyzing flow data obtained by 20 flow meters, and estimating future flow reductions associated with projected vacant land.

Evaluating Flow Reduction Strategies

This work included using the revised hydrologic/hydraulic model to develop alternate cost-effective flow reduction strategies, utilizing green infrastructure. The proposed improvements included:

• The installation of new separate storm sewers to collect local runoff
• Redirection of existing separate storm sewers, which currently discharge into the combined system
• Installation of new separate sanitary sewers to collect wastewater from sewer laterals and from existing separate sanitary sewers that presently discharge to the combined system
• Installation of four stormwater detention basins designed to remove pollutants and attenuate peak flows
• Miscellaneous improvements to five properties to divert wastewater and stormwater to the appropriate sewer

Evaluating Alternative Horizontal and Vertical Alignments

This work evaluated alternate sewer construction methods, such as open-cut, conventional two-pass tunneling, and micro tunneling; assessing alternative horizontal and vertical pipe alignments to minimize site disruptions, and evaluating shaft locations.

Advancing Conceptual Designs

This work included analyzing results of the geotechnical investigation and environmental site assessment, identifying required permits, easements, and areas of public disturbance; and preparing contract documents.