Introduction

B.A.N.G. Engineering and Associates was obtained to design a treatment facility for the city of Shelby, MS. This facility is to include a rapid mix, flocculation, and settling basin. Minimum design parameters provided by G.L.U.M.R.B. (Great Lakes Upper Mississippi River Board) were adequately met in the design. This design criterion ensures that the water treatment facility designed provides proper serviceability to the city of Shelby, MS.

The design of an efficient system is not enough in terms of properly designing a water treatment facility. An efficient system is one that has water flowing through the entire basin, rather than through just one area. A sedimentation basin’s efficiency, to a large extent, relies on the efficiency of the flocculation basin. The size, shape, and density of the floc entering the sedimentation basin will influence the settling rate of the floc. Typically, floc that is too small/large, has a low density, or irregular shape will not settle properly in the sedimentation basin. Floc can also disintegrate as it travels to the sedimentation basin. This is caused by a high water velocity and/or having several sharp bends in the system. Another issue that can occur during the treatment process is short circuiting. This inefficiency happens when water bypasses the normal bypass in the basin and reaches the outlet in a time that is less than the designed detention time. When water in the settling basin short circuits, this causes the floc to not have enough time to settle. It is for the reasons listed above that there are minimum design parameters that have to be met. If issues arise within the water treatment process, they affect the economy of the plant and the quality of the treated water.

Scope

The objectives of this studyare to:

  1. Design a rapid mix and flocculation basin
  2. Design a conveyance from the flocculation basin to the settling basin
  3. Design sedimentation basin
  4. Provide CAD drawing with dimensions of all design

These objectives were completed by applying the flow rate of the system to obtain dimensions for the flocculation basin. The velocity in the system could then be calculated and compared to standards provided by G.L.U.M.R.B. A simple conveyance was designed to move the water from the flocculation basin to the sedimentation basin. Again, dimensions for the sedimentation basin were calculated and compared to minimum design parameters to determine if the basin met the outlined criteria. This process proved to be an iterative process. Once the dimensions of both the settling basin and the flocculation basin were adequately obtained, a CAD drawing was made to provide an accurate visual representation of the designed basins.

Appendix 1: Hardy Cross Iterations

Appendix 2

Appendix 3

Appendix 4: Variability Chart of water supply and demand for Shelby, MS

Appendix 5: Initial flows and pipe diameters

Works Cited

Chin, D.A. Water Resources Engineering 2nd Edition. Upper Saddle River: Pearson Education, 2006.

"Drinking Water." 2013 ReportCard on Americas Infrastructure. ASCE, n.d. Web. 12 Sept. 2013. <