Effective Control Strategies for Highway Nonpoint Pollution

摘要

The goals of this research were the characterization of lateral pavement sheetflow and based on characterization results, development of passive in-situ treatment for metal elements and solids transported in storm water drainage. Characterization results were obtained from a highway experimental site which intercepted lateral pavement sheet flow directly from inter State Route 75 (I-75) in Cincinnati, Ohio. Measurements at the site included rainfall, flow and water quality parameters for 12 storm events over 3 years. Laboratory analysis included metal element concentrations and partitioning. Solids anlaysis included fractionation, particle size distributions (PSD) and specific surface area (SSA). Results indicated that Zn, Dc and Cu were mainly in dissolved form, and on an event basis exceeded USEPA and OEPA surface water quality standards. Based on characterization results, an in-situ treatment strategy called a partial exfiltration trench (PET) was developed. The PET functions by intercepting and infiltrating lateral pavement sheet flow influent while exfiltrating treated effluent to surrounding soils or to a perforated underdrain at the base of the trench. The body of the trench was filled with iron oxide coated sand (OCS) for adsorptive filtration of metal elements in the percolating stormwater. Results indicated that breakthrough capacity was controlled by particulate-bound metal element breakthrough. After one year of storm water loadings, PET removal efficiency exceeded 80 percent for dissolved and 70 percent for particlate-bound metal elements, respectively.