Development and Evaluation of Best Management Practices (BMPS) for Highway Runoff Pollution Control.

摘要

Polluted storm water runoff is commonly transported through Municipal Separate Storm Sewer Systems (MS4s). Currently, sufficient information is not available on development and evaluation of Best Management Practices (BMPs) within an MS4 boundary for highway storm water runoff treatment and management. The objectives of this research were to: a) develop and test the feasibility of roadside BMPs that rely on bioretention, infiltration, and slow conveyance of storm water; b) test combinations of plants and soil media that will be sustainable in Nebraska; and c) test the feasibility of using rubber chips as an alternative BMP medium. This project was conducted in two phases. In Phase I (07/2011-12/2012), four field-scale BMPs were designed, constructed and monitored, and four types of rubber chip mediated soil mixtures were tested in bench-scale columns for physical properties related to plant growth and infiltration as well as storm water treatment effectiveness. In Phase II (01/2013-12/2013), the four field-scale BMPs were monitored. In Phase I, it was found that a 50/50 mixture of rubber chips and sand had the best treatment, but lacked the best qualities for plant growth and may require addition of compost. The benefit of adding rubber chips as a low cost alternative material for filler did not outweigh the leaching of lead, copper and zinc. In Phase II, field tests indicate that the bioretention cells with the 30% loam 50% sand 20% mulch mix and with the 50% compost 50% sand mix had good vegetative growth and good physical characteristics to support vegetative growth and establishment. The infiltration trench had minimal sediment interception and clogging but showed slow drawdown times in the spring months. The filter trench had variable TSS removal percentages, with the side slope of the filter trench contributing a large amount of the solids loading. The check dam filters experienced significant sediment accumulation after the first storm event. However, it was found that drawdown times were still within the range for operation. The four BMPs tested are all functional and feasible for treatment of highway storm water runoff, with bioretention cells being the cheapest to construct ($0.91* ft3 of water quality volume of the watershed). Results obtained from this two-phase project can be used to design and build field-scale BMPs in eastern Nebraska (e.g., areas near Omaha and Lincoln).