1998-07-13_GENERAL DOCUMENTS - M1974052 (3)

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Mr. Glenn Mallory Coal Ash Pilot Project Proposal July 6, 1999 Page 2 36 domestic wells completed as bedrock aquifers (Larimie-Fox Hills Formation) in the Milton Reservoir area are also provided. A review of water quay data indicate that all wells sampled exceeded water quality standards for total spended)solids and a large percentage exceeded standards for pH. Field and analytical data documented by Reeder are presented in Attachment A. Prior to initiating the pilot project groundwater quality samples will be obtained and analyzed for pH, TSS, TDS, and RCRA metals. Samples will be obtained from no less than one up- gradient and two down gradient wells. 5. Water quality data for the St. Vrain River are limited. I have provided data as available from the USGS for the South Platte River drainage system and the St. Vrain River. Prior to initiating the pilot study field measurements such as pH, conductivity up and down gradient of the test plot will be measured. Periodic measurements will be made during the pilot project and the frequency of the measurements will be a function of the estimated groundwater seepage velocity. Available information regarding flow of the St. Vrain River and water quality of the South Platte River drainage is presented as Attachment B. 6. Mr. Gambrell, water commissioner for Division I, District 5 water district, indicated by phone conversation that there are no domestic or agricultural diversions off the St. Wain River in the study area. He did indicate that Public Service Company operates a diversion and that water is used for cooling purposes. As such, the potential for adverse impact to human health or agricultural resources is very limited. 7. Public Service Company generated analytical data indicating that fly ash is not a characteristic hazardous waste. Numerous analytical methods were used such as toxicity characteristic leaching procedure (TCLP). CGRS proposes that a sequential rolling extraction test and a column leaching test be conducted on the coal ash. A discussion of these tests and the loading calculations to the environment is provided below. It is proposed to dispose of the fly ash by burial. The fly ash contains chemical constituents (contaminants) that will be leached by groundwater that comes in contact with the buried ash. These chemical contaminants include metals and inorganic compounds such as sulfate. Also an increase in the total dissolved solids (TDS) of the groundwater that contacts the buried coal ash will occur. It is assumed that since the coal ash is generated from an incineration process, no organic compounds would be present in the coal ash. In order to predict the loading to the environment, the following laboratory tests are proposed: a "Sequential Rolling Extraction" test and a "Column Leaching" test. The "Sequential Rolling Extraction" test provides the total quantity of the chemical contaminants that may be potentially leached from the buried coal ash. The "Column Leaching" test provides the rate as a function of pore volume at which the chemical contaminant will be leached from the buried coal ash. The total quantity leached as well as the rate at which the chemical contaminant is leached from the coal ash may be dependent