Roxborough Turbidity

Justin Irving Philadelphia Water Department Subject: Increases in turbidity at 7302 (Roxborough High Service Pumping Station) and 7401 (Roxborough Standpipes). In reviewing the on-line turbidity data for both 7302 and 7401, I noticed increase in turbidity at both sites over the last 2 weeks. I originally noticed an increasing number of turbidity “spikes” at the 7302 site. As this problem persisted, I decided to analyze data from 7401, and 7300 (Roxborough Upper Basin Influent) in conjunction with the 7302 data to rule out any effects that might be related specifically to the 7302 on-line monitoring panel. The data from 7300 did not show similar spikes in turbidity, however, 7401 correlated well with 7302 and the turbidity spikes at both sites line up when overlaid. The nature of these changes are increases in turbidity spikes at both sites, not increase in baseline the baseline values. Below are graphs to illustrate the changes which have taken place. I plan to conduct a additional analyses to generate numerical tables to accompany the graphs. I will continue to watch these sites as well to determine if any additional changes take place.

Figure 1: The blue series is 7302 (Roxborough HSPS) and the green series is 7401 (Roxborough Standpipes). I used data from this period because there were several turbidity events in the interim period between 11/18/2009 – 11/24/2009 which were not indicative of the normal baseline behavior.

Figure 2: Once again, the blue series represents 7302 while the green series represents 7401. While the baseline does not appear to have changed significantly, there is significantly more “spiking” in the data from both sites. There are several instances where the spikes at both sites line up almost perfectly, with the spike occurring at 7302 slightly before 7401, which would make sense hydraulically.

Figure 3: Again, the blue and green series represent 7302 and 7401 respectively. The graph above shows the daily maximum values over the time range with the irregular data in the middle time period removed.

Figure 4: Once again, blue and green represent 7302 and 7401 respectively. This graph shows the daily standard deviation values across the time period of interest. This graph in conjunction with the maximum graph in Figure 3 illustrate the spiking changes which have occurred nicely.