Combined Sewer Overflow System

Our staff`s experience includes the development of concepts, coordination of hydraulics testing, and the design of drop shafts for major CSO programs in Rochester, New York, Milwaukee and Columbus. Our staff members had coordinated hydraulic testing, developed drop structure designs and performed structural designs for CSO projects in Cleveland, Ohio; Richmond, Virginia; and St. Louis, Missouri. This experience includes testing of model prototypes in hydraulic laboratories at the St. Anthony Falls Hydraulic Laboratory at the University of Minnesota and the Iowa Institute of Hydraulic Research at the University of Iowa. Our staff`s past assignments include drop shaft hydraulics of the Chicago boot type and later Milwaukee vortex flow drops. In both cases, hydraulic testing of physical models was required to establish the geometry of a structure that would effectively convey flows from near surface facilities to deep tunnel for further conveyance and/or storage.

As mentioned above, we have worked with the Iowa Institute of Hydraulic Research to perform physical modeling of complex structures. This also included modeling a tunnel overflow structure for a detention tunnel in Cleveland, Ohio. The hydraulic modeling confirmed the hydraulic performance of the design and also allowed us to further improve the design of the structure.

Our staff members also coordinated with the hydraulic laboratories to model and improve the design of vortex style drop structures that have been utilized on numerous CSO projects. Specifically, the development included hydraulic issues involving vortex flows, vortex conveyance, and inlet geometry. Our experience with the hydraulic laboratories allows us to efficiently handle very complex hydraulic challenges that require specialized knowledge.

In addition to our hydraulic design capabilities, DUE has extensive experience in the structural design of underground structures including approach channels, tangential inlets, drop shafts, access shafts, connecting adits, and other underground chambers. Our experience includes assessment, selection, and design of initial ground support systems as well as design of final linings for underground structures. DUE recognizes the importance of designing the final lining of the structures to interact with the surrounding soil or rock and typically utilizes computer structural programs to aid in the analysis. A list of previous projects, which DUE team members have designed the shaft structures, is attached.

Our involvement in the NYC DEP Oakwood Beach Interceptor system resulted in development of "simple drop" technology that produced large savings. The same principle was utilized in re-designing of the drop structures for Cleveland`s CSO program. Again, substantial savings were gained from the adaptation of our designs.

Based on previous hydraulic studies we participated in, DUE is capable of designing vortex drop structures for flows up to 2,140 mgd (3,320 cfs) without additional hydraulic modeling. We are also able to design "boot" type (Chicago) drop structures. We have previous experience with selecting and designing shallow non-vortex drops (less than 40 feet), as well as "simple drops" for smaller flow conditions (less than 30 mgd).