Laserfiche WebLink
Mr. Glenn Mallory <br /> Coal Ash Pilot Project Proposal <br /> July 8, 1998 <br /> Page 3 <br /> on the pH of the ground water that will come in contact. It is proposed to conduct both of <br /> the laboratory tests described below at three different pH values: 5, 7 and 8. <br /> • Sequential Rolling Extraction Test: <br /> With this test, a specified weight (e.g. one-kilogram) of the coal ash is combined with a <br /> specified volume of water (e.g. one liter) and rolled in a bottle for a specified period of <br /> time (e.g. 24 hours). This represents a single extraction. The concentration of the chemical <br /> contaminant is then measured in the water. The test is repeated for several sequential <br /> extractions until almost all of the chemical contaminant has been extracted from the coal <br /> ash. This normally requires three or four extractions. The "Sequential Rolling Extraction" <br /> test provides the total quantity of the various chemical contaminants that may be potentially <br /> leached from the coal ash. <br /> • Column Leaching Test <br /> With this test, a certain weight (e.g. one-kilogram) of the coal ash is placed in a column. <br /> Next, one pore volume of water is passed through the column and the concentration of the <br /> various contaminants measured in the outflow water. The test is then repeated for several <br /> sequential pore volumes of water. The total number of pore volumes used in the test <br /> depends on the rate at which the chemical contaminant is leached and on the expected <br /> number of pore volumes that will flow through the buried coal ash during the time period <br /> of concern. This test provides the rate at which the chemical contaminant is leached from <br /> the coal ash as a function of pore volume of water. <br /> Based on the above laboratory tests and on the estimated rate of groundwater flow through <br /> the buried coal ash, the loading rate of the various chemical contaminants can be calculated <br /> as a function of time. This would require a knowledge of the hydraulic conductivity K of <br /> the existing aquifer material and the coal ash. Aquifer testing in the field as well as <br /> permeameter tests in the laboratory would be used to determine the hydraulic conductivity <br /> of the existing aquifer material as well as the coal ash.This is a non-agitated test and would <br /> allow for the determination of water quality verses pore volume flow through. We can also <br /> estimate the hydraulic conductivity of settled coal ash, which will allow us to estimate <br /> changes to local groundwater hydrology. <br /> 8. Public Service coal comes from a number of Colorado mines in Routt, Moffat, Delta and <br /> Gunnison counties. These mines include West Elk, TwentyMile, Powderhorn, and <br /> ColoWyo. This coal is normally purchased under long term contracts which specify certain <br /> analytical parameters. Therefore, the chemical and physical properties of the coal (and <br /> resulting ash) do not change significantly from year to year. Analytical information for <br /> each of these coal sources is available as is the analytical information on the ash, which has <br /> already been provided in our earlier submittal. Comparisons of analytical data completed <br /> in the early 1990s with recent data indicate little variation in any of the ash constituents. <br />