Monitoring Results

Results Analysis & Comparison
This study will compare the water quality of runoff discharging from 3 types of pervious road surfaces, 3 types of amended bioswales, and conventional impervious asphalt.

All samples are analyzed by the City of Yakima Wastewater Treatment Laboratory for common urban stormwater pollutants including:
  • Biological oxygen demand (BOD)
  • Copper (Cu)
  • Total suspended solids (TSS)
  • Lead (Pb)
  • Fecal coliform (FC)
  • Zinc (Zn)
  • Total petroleum hydrocarbons (TPH)
Mean Values of Previous Monitoring Events
  • November 18, 2010
  • April 5, 2011
  • July 13, 2011
  • October 6, 2011
  • November 7, 2011
  • April 18, 2012
  • November 8, 2012
Results Interpretation
  • The following graphs illustrate the lab results for each parameter listed above
  • % Swale = % of organic compost per swale
  • Error bars are the standard deviation of the mean
In a few cases, in particular with the 5% swales, the standard deviation of the mean exceeded the mean value because of high variability between sample events. The error bars for these mean values would have extended to less than zero, but these were stopped at zero since it is not possible for any of the data results to be less than zero.

Treatment Sites

Treatment Type
Site Numbers
Permeable Pavers
13 and 16
Porous Concrete
14 and 18
Porous Asphalt
15 and 17
10% Swale
1 and 4
5% Swale
2 and 5
0% Swale
3 and 6
Impervious Surface
7 through 12
Levels