The Philadelphia Suburban Water Company replaced the support gravel and media in four
of the dual media filters at the Pickering West Water Treatment Plant in Phoenixville, PA.
The support gravel and sand was replaced with the same size and quality in all of the
filters. The anthracite was replaced with the same effective size and quality in all of the
filters, but with different uniformity coefficients (one at 1.6 UC, one at 1.5 UC, one at 1.4
UC and one at 1.3 UC). Data gathered over a one-year period indicates substantial
differences in the filter run times and water quality. The lower the anthracite uniformity
coefficient, the longer the run times (up to 50% longer), the fewer the backwashes (up to
33% less) and the better the water quality (up to 38% less 2-5 micron counts). This paper
will present the methodology and results of the full-scale operational test.