Comparing the Impact of Stormwater Runoff from Different Land Uses on Adjacent Properties

Stormwater runoff is known to have detrimental impacts to surface waters as it enters these waters untreated. The impact has been related to land use, but side-by-side quantitative comparisons are limited. In this study, we look to compare a typical suburban residential development of 18.8 hectares with a large box store property of 10.3 hectares immediately adjacent. Although covering a smaller area, the box store and associated parking areas are assumed to have nearly 100% impervious cover, while the larger residential development has approximately 22% impervious cover. Stormwater runoff sampling is completed at the single point of discharge for each area, and is ongoing. Results to date show no variation in pH between the two sites with values averaging 7.5. Turbidity values, in the range of 100 to 120 NTU, are similar for both areas on an event basis, indicating the efficacy of the settling basins within each system. Specific conductivity, however, shows significant differences with the residential area having values averaging 590 ƒÝS while the box store area averages 820 ƒÝS. Ongoing sampling and detailed chemical analyses will evaluate seasonal trends and the relationship to event timing on major water quality parameters.