2001-07-02_GENERAL DOCUMENTS - M1974052

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Mr.Roger Doak Coal Ash Pilot Project Proposal June 26,2000 Page 2 remainder of the column was filled with the sand and gravel. The column length was increased to 30 inches to accommodate the pore volume needed for sampling and to provide a larger volume of ash. The column was agitated as it was filled to induce settling. Once the column was filled water was allowed to preferentially fill the gravel portion of the column and wet the ash. Water was periodically introduced into the column as the water level in the gravel lowered. This procedure was repeated until the entire column was saturated. Prior to initiating the leaching test the upper two inches of the column was filled with gravel to occupy the space created by settling and to prevent the diffusion plate from being blocked by the less permeable ash. Photographs of the leaching experiment are presented in Attachment A. The proposed trench will be 10 feet in width. The seepage velocity beneath the ash deposit should be on the order of 2 to 3 feet per day. Using an average rate of 2.5 feet per day four days would be required for water to cross the ash. The flow rate through the column was adjusted for one pore volume (calculated at approximately 1.5 liters) in four days so that the total contact time of the water with the ash in the column would be reflective of field conditions. All of the analytical parameters were inorganic in nature and fluorescein, an organic dye, was added to verify that water flowing through the column was not bypassing the ash or soil along the column wall. No preferential flow was observed along the column wall throughout the experiment. As mentioned the leaching medium was water obtained from the Varra property. Water obtained from the Varra property on February 28 and April 5, 2000 was used in the experiment. After leachate samples were collected they were measured for pH, temperature and conductivity. The samples were then forced through a 0.45 um cellulose acetate filter and transported to the laboratory for analysis. The samples were analyzed for Al, Sb, As, Ba, Be, B, Ca, Cd, Cr, Co, Cu, Fe, Pb, Li, Mg, Mn, Me, Ni, P, K, Se, Ag, Na, Ti, TI, V, Zn, Hg, U, alkalinity as bicarbonate, carbonate and hydroxide and chloride, fluoride sulfate nitrate and nitrite. Laboratory data sheets are presented as an independent document with this correspondence. The ash was analyzed for the same parameters as the water samples and the data are presented on Table 1. It should be noted that the ash digest results may not reflect compositional data generated by Public Service Company and presented previously as the digestion processes were different. The analyses are very comparable to the ash samples analyzed in the CSU leaching experiments. The ash used for the modified column test was a 50150 mixture of Class F silo ash with gypsum and Cherokee 4 fly ash with sodium. These ashes were used as they constitute the bulk of ash generated at the Cherokee power plant and would be the primary ashes used in the Varra project. Bottom ash will not be used as previously intended due to its economic value. A review of Table I shows that of the twenty seven parameters with associated standards, the soil-ash leachate exceeded the standard(s) for antimony, beryllium, manganese, selenium, and nitrite on one occasion for each parameter and for sulfate for all samples submitted. Antimony and beryllium were detected near the method detection limit in samples obtained from pore volume two and eight, respectively. Nitrite and selenium were detected at 5.4 and 0.03 mg/L in samples obtained from pore volume one. The detection of nitrite is somewhat unusual as nitrite is very unstable in the environment and is readily oxidized to nitrate. None of the leachate samples had sulfate levels in excess of background levels detected in the pond water, which exceeded the sulfate standard for all samples submitted.