1999-04-12_HYDROLOGY - M1974052 ‎(7)‎

• Permit No: M1974052
• IBM Index Class Name: Hydrology
• Doc Date: 4/12/1999
• Doc Name: WORK PLAN VARRA COAL ASH BURIAL PROJECT WELD COUNTY COLO CGRS #1-135-2755
• Media Type: D
• Archive: No

' CGRS, lac. • •

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much less than those resulting from the SELP testing, which was a more aggressive test. Boron,
Fluoride and manganese appeared to be the most leachable analyzes in this test.
3.3 "Svothetic Ground Water Leachiag Procedure" (SGLP)
Analytical results for the SGLP are presented in Table 4. Water was obtained from the gravel
quarry pond immediately adjacent from the proposed study area (Figure 3) and was used as the
leaching fluid. This water is considered to be representative of local groundwater quality and was
analyzed to determine backgound water quality of the leaching medium. A review of Table 4
shows that the only analytes that were in excess of any standards were boron, manganese,
selenium, fluoride, sulfate and nitrite. The water obtained from the quarry had sulfate and Fluoride
concentrations of 2,900 and 4 mg/L, respectively. These concentrations are considered high enough
to inhibit leaching of these analyzes to the surrounding groundwater regime.
3.4 "Svothetic Groundwater Column Leaching Procedure" (SGCLP)
The results for the SGCLP are presented in Table 5. A review of Table 5 shows that boron is the
most leachable element with fluoride and sulfate being the most prevalent nonmetal constituents in
excess of applicable standards. With the exception of aluminum and barium all constituents of
concern decreased dramatically with respect to increasing pore volumes. It appears that variations
in pH may have had a slight affect on leachability of different coal ash samples.
3.5 Overview of Laboratory Data
The various testing regimes document hydraulic and leaching characteristics of coal ash.
Permeabilities of coal ash varied over three orders of magnitude. The hydraulic conductivity of
bottom ash closely approximated recycled concrete and recycled asphalt and is comparable to
permeabilities associated with medium and coarse-grained sands. Fly ash samples were three
orders of magnitude less permeable than bottom ash and non-ash samples and have permeabilities
comparable with silt and clay.
In general, the most prevalent elements or compounds detected in the leaching studies coincide with
the general composition of coal ash (aluminum, barium, boron, iron and manganese). The intent of
SELP study was to determine the maximum leachability of coal ash under different saturated
envvonments -namely different pH values. Fluctuations in pH did seem to have an affect on the
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