Laserfiche WebLink
11 <br />' <br /> homogenized with sidewall soils on either side of the SHT and some bottom <br /> soils. Composite soil samples were collected from two locations (station markers <br /> 22+50 and 23+00) in the stabilization cells. The samples were placed in plastic <br />' bags for screening with the PID. The samples were then placed in four, 2-ounce <br /> laboratory supplied clean glass jars. The samples were placed on ice in a cooler <br />1 and transported to ECS for BTEX, TVPH and benzene TCLP analysis. <br /> Based on the lab results, the total benzene in two samples was 0.42 mg/Kg and <br /> 6.5 mg/Kg. This is below the 20X TCLP factor of 10 mg/Kg for total benzene in <br />t soil. However, the TCLP Benzene concentration for these samples was 0.72 <br /> mg/L and 3.5 mg/L, respectively. The station markers and sample locations are <br /> shown on Figure 3. A summary of the waste characterization samples is <br />' included on Table 5 and 5A. <br /> Due to the high benzene and TCLP results, E-21 evaluated various other options <br /> <br />' for stabilization and disposal. Introduction of cement as an absorbent to stabilize <br />the slurry was evaluated for feasibility. The slurry would then be homogenized <br /> and excavated for off-site disposal. The CDPHE was contacted and initial <br /> approval to evaluate this option was obtained from Mr. Walter Avremenko. <br />' <br /> On January 10, 2007, 12 cubic yards of cement was added to the SHT in a 25- <br /> foot length between station markers 21+75 to 22+00. A sample was collected <br /> and submitted for analysis. The total benzene in the sample was 47 mg/Kg. The <br />' TCLP benzene concentration was 2.8 mg/L. <br /> On January 11, 2007, a 50-foot length of the SHT near the west end was <br />' selected for cement stabilization between station markers 19+50 to 20+00. <br /> Eleven cubic yards of cement was introduced in 2 ratios over approximately 25 <br /> feet of the SHT. Seven cubic yards of cement were added to the SHT between <br />' station markers 19+50 to 19+75. Four cubic yards were added to slurry between <br /> station markers 19+75 to 20+00. Samples were collected from each test area <br /> and submitted for BTEX analysis only. The benzene concentrations were 8.9 <br />' mg/Kg and 7.2 mg/Kg, respectively. <br /> On January 16, 2007, two additional yards of cement was added to the test areas <br /> between station markers 19+50 and 20+00. A composite sample was submitted <br /> for BTEX analysis. The benzene concentration was 1.7 mg/Kg. <br />Also, on January 16, 2007, two additional yards of cement were added to the test <br />' areas between station markers 22+00 and 23+00 as this test area had not been <br />stabilized using cement. A composite sample was submitted for BTEX analysis. <br />The benzene concentration was 13 mg/Kg which is higher than previous sample <br />' results. <br />The station markers and sample locations are shown on Figure 3. A summary of <br />the waste characterization samples is included on Table 5 and 5A. The <br />' laboratory reports are included in Appendix 3. <br />Based on the sample results from test areas and response from CDPHE of the <br />status report submitted by E-21 on January 22, 2007, following the solidification <br />testing, it was determined that the waste would require disposal as a hazardous <br />waste. The addition of the cement as an absorbent did make the liquid slurry <br />more soil-like and allowed handling the material as a solid. <br />12