1999-04-29_GENERAL DOCUMENTS - M1974052

Home Browse Search

• • III IIIIIIIIIIIIIIII 999 STATE OF COLOMDO DIVISION OF MINERALS AND GEOLOGY Department of Natural Resources 1 31 3 Sherman St . Room 215 Denver,Colorado 80203 DIV;AM N OF Phone:1303I 866-3567 MINERALS FAX (3031 8 3 2-8106 GEOGY April29, 1999 RECTION MINING-SAFETY Mr. Chris Varra Varra Co., Inc. &II Owens 12910 Weld County Rd.#13 Governor Longmont,CO 80504 Greg E.Watcher Execunve Director RE: Technical Adequacy Review of Application for Technical Revision 003 to Permit No.#M-74-052, Michael B.re to q Y PP Division Director Varra Co., Inc. Pit Dear Mr. Varra. This letter is being written in answer to your response to the initial Division of Minerals and Geology (DMG) technical adequacy review of the application for Technical Revision 003, Permit#M-74-052, Pit No. 1.The proposed evaluation to dispose of coal ash by burying it in saturated media still lacks adequate details in the following areas: I) The proposed groundwater monitoring is not acceptable to the Division.The description of sampling as taking place"on three occasions between one and three months apart'prior to the project is not adequate to qualify as a pre-project background groundwater monitoring program,and it does not specifically refer to which parameters will be tested during the pre-project phase. The groundwater flow direction estimation is still (see Harry Posey's attachment of the February 4 adequacy review letter)based on too few points to be used for this project. Establishing baseline surface and groundwater is required for the Division to make an informed decision about this revision.The map of the well monitoring locations appears to be only an estimation of the final location of the burial trench which may change based on groundwater flow data yet to be gathered. This map also does not show the location of the proposed downstream monitoring point on the St. Vrain Creek. Please submit this information. 2) The specific remediation procedure proposed in this submittal is not adequate. While removal of the soils is an appropriate response to findings of groundwater quality degradation, no mention is made of the possible treatment of contaminated groundwater. The proposed re-burial of the flyash in a"dry impoundment" is not considered sufficient remediation either. If the materials are leaking contaminants, they must either be confined to an adequately lined facility(with design based on the contaminants in question). "Additional remediation commensurate with the extent and degree of impact"does not address specific elements of design which can be reviewed and,therefore, can not be approved by DMG. We appreciate the commitment to contact DMG immediately should the monitoring indicate an unacceptable degradation of groundwater quality. However, further plans for remediation measures are required, and must be submitted prior to approval. 3) Details on the soil formations and aquifers in the immediate area are still incomplete. To be more specific, the rate of transmissivity of the surrounding soils, as well as the groundwater levels in the area proposed, must be submitted prior to any DMG decision regarding the proposed burial of flyash in the area. Containment facility design can not be evaluated until this formation and specific liner designs are submitted. Additionally, the possibility of contamination of nearby wells can not be evaluated without this data, and neither can the possibility of the re-routing of groundwater flows due to differences in soil density. The possibility of pooling of water at the surface, due to a sharp drop in transmissivity-or the creation of a new flow path around or under the trench, must be addressed. Please address these concerns. 4) We appreciate the map showing the locations of the nearest registered wells. However, the registered use of those within one-half mile has not been included. Please submit this. 5) According to Rule 3.1.7(1). "operations that may affect groundwater shall comply with all state-wide groundwater quality standards established by the Water Quality Control Commission." What is the classification of the