Built in 1953, the Little Miami Waste Water Treatment Plant is the second largest treatment plant operated by Metropolitan Sewer district of Greater Cincinnati. The existing facility had five climber type bar screens and three detritus type grit tanks. The treatment plant was experiencing a large build-up of grit in both the primary and secondary tanks.
Shrewsberry was responsible for the condition and capacity assessment of the preliminary treatment processes and equipment and writing of the WWTP Facility Plan. Evaluations were conducted on the ½ inch bar screens and the detritus tanks. Grit samples were taken in the screen effluent channel and detritus tanks effluent to determine grit removal efficiencies.
Based upon the outcome of the assessment, Shrewsberry recommended replacement of the medium screens with a ¼ inch bar screen and the installation of new vortex grit removal systems. Conceptual design drawings were prepared to illustrate the new additions to the plant and how construction could take place while leaving the existing plant in operation.
Shrewsberry recommended the current method of handling the screenings and grit also be replaced. The screenings were being dumped onto a conveyor and into a hopper for disposal. Shrewsberry recommended installation of a new conveyance system due to the increased volume of screenings and a washer/compactor to remove the organics from the screenings and decrease volume. The grit had no washing to remove organics. The recommendation was to install a grit washer and dewatering device for each of the proposed grit removal tanks.