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252 Advances in Productive, Safe, and Responsible Coal Mining

and DP 3 consisting of codisposal of blended CCPW (84%) and FCPW (8%) with
limestone addition (8%). The geotechnical properties of all three mixtures were char-
acterized including moisture-density relationships developed using standard Proctor
tests (ASTM D698-12e1 Method C) [16].
Finally,field-scalekinetictestswereconductedoutdoorsatthepreparationplantcom-
plex.Thisendedupbeingdoneintwophasesduetoatornadodamagingsomeoftheinitial
columns. During the first phase, three duplicate test column sets (FC-1–FC-6) were
constructed using 200L (55gal) barrels and monitored for 19months. In the second
phase, three more duplicate test column sets (FC-7–FC-12) were constructed with
380L (100gal) polycarbonate livestock watering troughs (see Fig. 13.2). Phase 2
column mixes were 100% CCPW for DP 1; 93.3% CCPW and 6.7% dewatered
FCPW by volume for DP 2; and 86.7% CCPW, 6.7% dewatered FCPW, and
6.7% ground limestone by volume for DP 3. Assuming normal porosity of 16%,
approximately 300kg (650lb) of CCPW were packed into each column. Sand cone
tests were performed during construction to determine dry unit weight and moisture
content. Phase 2 columns were leached in free-draining mode for 19months (16
leach cycles) with pore-water and leachate samples collected once per leach cycle
( 35days). Sample temperature, pH, and dissolved oxygen (DO) were measured in
the field. As soon as samples arrived in the laboratory, temperature, pH, and
specific conductance (SC) were measured. Alkalinity and ferrous iron were deter-
mined within 24hours after sample collection. All water sample quality results
were statistically analyzed using spreadsheet-based models.

13.2.1.2 Results and analysis

Table 13.1 shows particle size distributions for CCPW and limestone samples. FCPW
was uniformly <0.074mm (0.0029in). Initial moisture content of CCPW was 11.5%,
dewatered moisture content of FCPW was 31.9%, and initial moisture content of agri-
cultural limestone was 0.1%. Therefore, blending limestone with CCPW and FCPW in
the DP 3 mixture significantly reduced its overall moisture content. Table 13.2 shows

Rainfall
Lysimeter sampling head
Clay
378 L (100-gal) poly stock tank
Fine sand
Ceramic cup lysimeter
Compacted coal waste
Chert underdrain
18.8 L (5-gal) pail
Sample drain

Fig. 13.2 Schematic and photograph of field-scale kinetic test columns [2].