FIELD DOCUMENTS - Laserfiche WebLink

Home Browse Search

Background Levels of Iron in Soil by Vertical Horizon 45000 -- - -- - - 40000 35000 w 30000 a 25000 012 5 it 0>-2 5<10 ft 20000 O>-10 it C 0 u 15000 10000 5000 0 Vertical Horizon SUMMARY AND CONCLUSIONS Computer algorithms were used to automate the identification of background locations for inorganic chemicals in ground water and soil.These procedures identified large numbers of background locations and a more than adequate sample size which was used to determine California-wide background levels for 25 inorganic constituents. These data provide insight on background variability across California Air Force bases.The 951h percentile statistic for an individual constituent is a good representation of background level,given the inherent complexities associated with analyzing these large and diverse samples. Barium,magnesium,and sodium were highly detected in ground water;while aluminum,barium,chromium,copper,iron,magnesium,manganese,vanadium,and zinc were highly detected in background soils. Other constituents were not commonly detected in ground water(antimony, arsenic, beryllium,cadmium,cobalt,copper,cyanide,lead,mercury,nickel,selenium,silver,and thallium)or in background soil(antimony, cadmium,cyanide,mercury,molybdenum,selenium,silver,and thallium). For some analytes(antimony and chromium in ground water and arsenic,beryllium and iron in soil)regulatory limits are placed close to or below background levels. These results can not replace site-specific background data. They do represent extensive sampling over a significant range of California environments,and should be useful in putting local sampling and analysis outcomes into perspective. The Department of Toxic Substances Control(1997)has guidance for one approach to evaluating site-specific background. REFERENCES American Society for Testing Materials (ASTM), 1996, Provisional Standard Guide for Developing Appropriate Statistical Approaches for Ground-Water Detection Monitoring Programs,Designation: PS 64-96. Department of Department of Toxic Substances Control,1997. Selecting Inorganic Constituents as Chemicals of Potential Concern at Risk Assessments at Hazardous Waste Sites and Permitted Facilities. February,1997. EPA,Office of Solid Waste,1989,Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities,Interim Final Guidance. EPA,Office of Solid Waste, 1992,Statistical Analysis of Ground-Water Monitoring Data at RCRA Facilities,Addendum to Interim Final Guidance.