00983436

Component

https://doi.org/10.3141/1890-16

http://scholar.google.com...mith&publication_year=2004

A 2-year water quality monitoring project was conducted to evaluate the removal of storm water contaminants by existing vegetated slopes adjacent to freeways. Objectives of the study were to generate design criteria and to determine whether standard roadway design requirements result in buffer strips with treatment equivalent to those specifically engineered for water quality performance. Variables such as width, slope, vegetation density, and hydraulic loading were evaluated by studying the runoff through existing vegetated slopes at four locations in northern California and four locations in southern California. At each location, concrete channels were constructed to capture freeway runoff after it passed through existing vegetated strips of varying widths. The quantity and quality of the runoff discharged from the buffer strip were compared with freeway runoff collected at the edge of pavement. Buffer strips consistently reduced the concentration of suspended solids and total metals in storm water runoff. The strips were also effective in removing dissolved metals when the edge of pavement concentrations were sufficiently high. Little or no change in concentration was observed for nitrogen and phosphorus. Concentrations of organic carbon, dissolved solids, and hardness increased. For the constituents exhibiting a decrease in concentration, steady-state levels were generally achieved within 5 m (16 ft) of the pavement edge for slopes commonly found on highway shoulders and where the vegetation coverage exceeded 80%. Slope, vegetation type and height, highway width, and hydraulic residence time had little or no impact on the discharge concentrations.

This paper appears in Transportation Research Record No. 1890, Highway Facility Design 2004, Including 2004 Thomas B. Deen Distinguished Lecture.

00983421

English

p. 129-140

2004

Transportation Research Record

0309094860

Figures (2) ; Photos (1) ; References (8) ; Tables (13)

Metals; Nitrogen; Organic compounds; Phosphorus; Pollution control; Roadside; Runoff; Slopes; Suspended sediments; Vegetation; Water quality management

Buffer strips

Northern California; Southern California

Highways; Hydraulics and Hydrology; I26: Water Run-off - Freeze-thaw

TRIS, TRB, ATRI

Dec 28 2004 12:00AM

• AESTHETIC INITIATIVE MEASUREMENT SYSTEM: A MEANS TO ACHIEVE CONTEXT-SENSITIVE DESIGN
• ATTRIBUTES AND AMENITIES OF HIGHWAY SYSTEMS IMPORTANT TO TOURISTS
• CHARACTERISTICS OF SNOWMELT RUNOFF FROM HIGHWAYS IN THE TAHOE BASIN AND TREATMENT INVESTIGATIONS FOR IMPROVING RUNOFF QUALITY
• COMPATIBILITY OF VEHICLES WITH SAFETY BARRIERS: HEAD EJECTION THROUGH SIDE WINDOWS
• CONTEXT-SENSITIVE DESIGN: WILL THE VISION OVERCOME LIABILITY CONCERNS?
• DEVELOPMENT OF GUIDELINES FOR PLACEMENT OF GUARDRAIL POSTS IN ROCK
• DYNAMIC ACTIONS ON BRIDGE SLABS DUE TO HEAVY VEHICLE IMPACT ON ROADSIDE BARRIERS
• EVALUATION OF STORM WATER CATCH BASIN INSERTS FOR TRANSPORTATION FACILITIES
• ISSUES IN AUTOMATING UTILITY PERMITS AT TRANSPORTATION AGENCIES
• LS-DYNA SIMULATION INFLUENCE ON ROADSIDE HARDWARE
• METHODOLOGY TO EVALUATE THE FLAIL SPACE MODEL BY USING EVENT DATA RECORDER TECHNOLOGY
• MIDWEST GUARDRAIL SYSTEM FOR STANDARD AND SPECIAL APPLICATIONS
• MULTIDIMENSIONAL FRAMEWORK FOR CONTEXT-BASED DESIGN OF MAJOR URBAN THOROUGHFARES
• NARROW CONNECTICUT IMPACT-ATTENUATION SYSTEM: SYNOPSIS INCLUDING NCHRP REPORT 350 CRASH TEST RESULTS
• OVERLOOKED LOCAL SEDIMENT SCOUR MECHANISM