Note: This is the text from a report I obtained from Rick Wenta of the Public Health Dept. No author was listed. I was unable to reproduce the figures and table--so if you would like to see them, please email me. I have listed the descriptions of the sample points at the end.
The objective of this study was to obtain an indication of salt application rates on private property. The study site was chosen because the mall parking lots and access roads represent a substantive area of impervious surface that is maintained by private contractor.
Three private storm drainages from the East Towne Mall area and two City storm drainages from East Springs Drive were sampled for chloride during periods of snow melt (see Figure 1). Sampling was limited by the collection method as storm sewer flows were obtained with a peristaltic pump.
Sample point 1 (see Figure 2) is a private apron end draining to the east branch of Starkweather Creek. It collects runoff from parking lots and the access road west and north of Menard’s. Sample point 2 is a City apron end (AE 6829-001) that discharges in the same location as sample point 1. It contains runoff from East Springs Drive and runoff from parking lots at Menard’s and lots and access roads to the north. Grab samples were collected at these sample points.
Sampling began in February. Sewers were inspected for flow whenever conditions were favorable. Several of the sample points were well below the street surface, requiring the use of a peristaltic pump. Consequently, samples were only taken when the flow was deep enough for the pump to draw water; standing water was not sampled.
Figure six displays the results graphically. On February 2, meltwater from the strip mall area west of Menard’s (private apron end) contained the highest level of chloride. However, the isolated street runoff (IN 6928-010) was higher than that of the combined city/private flow of AE 6829-001. This would suggest that the runoff from Menard’s parking lot and areas north diluted the street runoff significantly.
The second sampling event, on February 16, showed chloride levels from the strip mall area had dropped. The isolated street runoff sample again was higher than the combined sample at AE 6829-001. Dilution from the Menard’s parking lot sewer again appears to provide significant dilution. Subsequent sampling events yielded similar results for all sample points suggesting that the majority of the road salt had already been flushed from the system.
Although limited in scope and ability to quantify road salt application, the results suggest that large scale commercial areas probably contribute similar levels of chloride to meltwater as City deicing operations on main arterial roadways.
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Sample point 1 (see Figure 2) is a private apron end draining to the east branch of Starkweather Creek. It collects runoff from parking lots and the access road west and north of Menard’s.
Sample point 2 is a City apron end (AE 6829-001) that discharges in the same location as sample point 1. It contains runoff from East Springs Drive and runoff from parking lots at Menard’s and lots and access roads to the north. Grab samples were collected at these sample points.
Sample point 3 (see Figure 3) is a City storm inlet (IN 6828-004) that collects runoff from the gutter and conveys storm water from Menard’s outside storage area.
Sample point 4 (see Figure 4) is a City storm inlet (IN 6928-003) that collects runoff from the gutter (some of which is from Menard’s parking lot) and conveys storm water from Menard’s parking lot and most of the parking lot and access roads north of Menard’s.
The final sample point (see Figure 5) is a City storm inlet (IN 6928-010) that collects street runoff and conveys storm water from: the north on East Springs Drive; Anamark Drive; High Crossing Boulevard; East Washington Avenue from about the 4700 block to the interchange.
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