Highway runoff is a significant source of nonpoint pollution to surfoce and ground waters. Underground disposal of stormwater has several advantages, such as recharge of ground water resources and reduction of flow rates at existing storm sewer outfa11s. However, there are few studies on the effects of underground disposal of stormwater on the qua1ity of ground water. The purpose of this stucty was to examine the changes 1n lead, zinc, and specific conductance in highway runoff that is routed to an underground disposal facility as the water passes through the unsaturated soil to the surficia1 aquifer. An exfiltration pipe in downtown Orlando, Florida, was selected for the stucty. The stucty was conducted to learn more about the fate of lead and zinc by observation of a working system. Sampling locations were established in both the saturated and unsaturated ground water zones in the vicinity of the pipe. Teflon vacuum lysimeters were placed at three different depths to collect water from the unsaturated zone, and shallow wells were augured at the site to obtain water from the surficial aquifer. Samples were collected for six storm events over the period from June 1 984 through August 1 985, and samples were also collected for one between-storm period. Rainfall also was recorded near the site. Results of the statistical work done for the stucty indicated that zinc values in the unsaturated zone were similar to each other, but the values were different significantly between the saturated and unsaturated ground water sampling locations. From existing literature it is known that lead exists primarily in particulate form, not dissolved, so removal of particulate lead may occur by entrapment in the pipe. Specific conductance was significantly different in the shallowest lysimeter from values at all other locations, and a decrease in specific conductance with depth was noted. This may indicate a reduction in total ionic content, possibly due to sorption processes occurr1ng in the soil, precipitation, and transformation by plants and bacteria. Results of the study indicate that lead and zinc concentrations in ground water around the pipe do not appear to be affected significantly by infiltration of stormwater from the exfiltration pipe.
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Master of Science (M.S.)
College of Engineering
Length of Campus-only Access
Masters Thesis (Open Access)
Schiffer, Donna M., "Distribution of Lead and Zinc in Groundwater Around an Exfiltration Pipe Including a Study of Specific Conductance" (1986). Retrospective Theses and Dissertations. 4944.