4.1  Initial Baseline Soils Sample Data

4.1.1  Projectile-Contaminated Sand

Samples collected from the projectile-contaminated sand at B-20 contained a moisture content of 14.9 percent and 1.6 percent organic matter. The majority of the organic material consisted of ash and burned wood fragments. The soil contained 364,989 mg/kg of total lead, of which 258,885 mg/kg was particulate lead. Gradation of projectile contaminated soils revealed that 24.6 percent of the soil is larger than mesh size 4, and 23.8 percent, the second largest fraction, is less than sieve 200. Analysis also demonstrates that the largest fraction of metal particulate lies in soils with a mesh size greater than 4.

4.1.2  Sifted Soils

The sifted soils from the area had a moisture content of 17.5 percent and 0.3 percent organic matter, organic material consisted primarily of ash and burned wood fragments. The soils contained approximately 2,123 mg/kg of total lead, of which 1,069 mg/kg was particulate lead.

4.2  System Performance Soil Sample Data

4.2.1  Projectile-Contaminated Soil

Density treatment of projectile-contaminated sand achieved a 61 percent removal rate for lead contaminants, yielding a final lead concentration of 143,041 mg/kg. The majority of the recoverable material consisted of lead slugs, copper-jacketed bullets, and fine-grained metallic residue. While the overall lead concentration in soils decreased, the concentration in the 200-sieve and <200-sieve soil fractions increased (see Figure 4.1). This increase may be attributed to the attrition of larger lead particles during the density separation process.

The leachable lead concentrations (via TCLP analysis) within the treated projectile-contaminated soils was 21.5 mg/l. The results indicate that soil washing alone will not meet project objectives to treat the waste to less than hazardous levels.

4.2.2  Sifted Soils

Soil washing of the sifted soils was less effective than for the lead projectile contaminated sand. There was a 50 percent decrease (1,055 mg/kg) of lead contaminants following density treatment. As with the projectile-contaminated sand, the lead concentrations in the smaller soil fractions increased following density treatment.

The leachable (via TCLP analysis) lead concentrations within the sifted soils following density treatment were 0.2 mg/L.

Figure 4.1 - Density Treatment of Projectile Sand

Figure 4.2 - Density Treatment of Soils