A SURVEY OF LEAD CONTAMINATION IN SOIL ALONG INTERSTATE 880, ALAMEDA-COUNTY, CALIFORNIA

This study was undertaken to determine the levels of lead in soils tak en from yards of homes in close proximity to a major freeway. Soils we re collected from the yards of homes in communities adjacent to the fr eeway and within a 1-mile radius. Samples were analyzed using U.S. Env ironmental Protection Agency (EPA) methods and atomic absorption instr umentation. Ten percent of the samples were split and sent to a second laboratory for quality control. The possibility of lead-based paint c ontributing to the contamination was eliminated by sampling more than 20 feet from the homes. The soils closest to the highway showed lead l evels exceeding California's and EPA's criteria for hazardous waste. A stratified sample of the depth of contamination in soils was also und ertaken. Previously identified ''hot spots'' (soils with lead levels e xceeding 500 ppm in the top 0. 75 inch) were core sampled. Results ind icated 90% of the subsurface samples contained lead exceeding the surf ace contaminations. This may be attributed to decades of urban lead-la den dust deposition. As the use of leaded gasolines have diminished in the past decade, the uppermost layers of soil/dust contained lower am ounts of lead.