Cotter Cañon City Mill License Renewal Meeting January 13, 2003 at CDPHE Site Decommissioning Team Meeting Minutes

Transcription

1 Cotter Cañon City Mill License Renewal Meeting January 13, 2003 at CDPHE Site Decommissioning Team Meeting Minutes PRESENT CDPHE: Steve Tarlton, Phil Egidi, Phil Stoffey, Larry Bruskin, Ken Weaver (recorder) COTTER: Steve Landau, Preston Niesen, Clint Strachan (MFG consultant), Judd Adams (consultant & meeting facilitator and secretary) Site Decommissioning is a better term to use than reclamation plan. AGENDA We began with Tarlton s agenda outline which was a synthesis of CDPHE and Cotter items and shorted then into a general priority as follows, reflecting the consideration that items related to the Cotter lawsuit over Maywood materials would need to be deferred until later: 1. Ownership of subsurface rights 2. Cap cover design 3. Remedial soils volume (current plant, OPA, and windblown), including new Old Ponds Area Alternatives or comprehensive characterization plan. 4. Impoundment dewatering Future Meetings 5. Reclamation design standards 6. Decommissioning standards 7. Current plant debris volume 8. Borrow area reclamation 9. Onsite groundwater remediation 10. Physical and chemical characteristics of direct deposit material 11. Licensing venue 12. Authorized activities For each specific topic, 1. Begin with a presentation of available past knowledge and reports, and status of previously approved design and decisions. 2. Determine what data are critical to reducing the uncertainty in impoundment volumes, material acceptability, or reclamation costs. 3. Determine what data are missing and how to get the data. 4. If data cannot be obtained, or decision made in an appropriate time frame, what assumptions can be made? OWNERSHIP OF SUBSURFACE RIGHTS Preston explained the status of subsurface rights for the various parts of Cotter property (Cotter doesn t own them) and will follow up with a letter to CDPHE. CAP COVER DESIGN Clint made a presentation that showed how the present design was based upon, and where it was different from the two previous ones, WWL (1990) and ESCI (1995). The slope is the only difference. Site Decommissioning Team Meeting Minutes 1/13/03 Page 1 of 4

2 1. Slopes a) You begin the design process by deciding the direction of drainage, then consider grade, followed by vegetation. (1) 1990 the drainage was from the saddle to the east. (2) 1995 the cap was a dome with drainage off to all directions (3) 2003 drainage is to the south and then to diversion ditches back to the north. This design is considered superior because there is less erosion potential. b) When slope is 0.5%-1.5% vegetation is appropriate while rock is required for steeper slopes, for diversion channels, and aprons of diversion channels. (1) The 2003 cap design is appropriate for vegetation. c) Questions: (1) Could the 2 nd Impoundment be covered sooner (in order to minimize water consumption)? Response: 2003 design would permit this, but the 2 nd Impoundment is needed for evaporative capacity from pumpback water in the wetter years. (2) Could 2 nd Impoundment be recontoured if Primary elevation doesn t get much higher? Response: Material could be removed and replaced. Would not be ALARA because of worker exposure from rehandling contaminated material. (3) Do we have data on rock specs? Response: There is ample available local rock that meet NRC specs. 2. Cover/cap design layers of materials issues are radon emanation, infiltration, and biointrusion. a) 2003 design employs the same layers and characteristics. b) MFG for 2003 did an updated radon analysis to verify appropriateness of layers. c) There are other Infiltration models in addition to HELP. d) Design calls for grass cover with shallow root depth. 3. Cover foundation a) Design allows for an amount of dry material between the tailings and the cover. b) Question: How do you estimate time frame for settlement? Response[JNA1]: Some ways to calculate consolidation. Would have settlement instrumentation. 4. Cover borrow material will need to be characterized physically and radiologically to determine whether it meets standards to be used. Following Clint s presentation, Larry discussed the benefits of using an evapotransporation (ET) cover design. 1. ET is becoming the new standard along the Front Range. a) Tests find the design meets the 1.3 mm per year requirement for 300 acres, and thus meets the RCRA equivalent criterion. b) Because vegetation transpires the water in the soil, strict cover permeability requirement is met by an equivalent design. 2. The concept is a cover that works with, not against, plant growth. a) The top layer is 4 feet of vegetative rooting medium. b) Below is a foot biota barrier of rock riprap (<9 inches) to drain off any water than may go below the top layer, and to block further root growth. c) The next lower layer is foot of sand which acts as cushion and drainage d) Below is the foot clay radon barrier. e) Next down is another 0.5 foot sand cushion layer. f) Next down is waste/grade fill 3. The top layer is designed to allow water to penetrate and nourish the plant roots. Site Decommissioning Team Meeting Minutes 1/13/03 Page 2 of 4

3 a) It is deep enough to absorb expected water during the rainy season and not allow water to continue on down to the tailings. b) During the dryer parts of the year evapotransporation from plants dries out the top layer. 4. The greater number of feet of cover works effectively as a radon barrier, so the clay barrier may not be necessary. 5. The soil specifications are based upon agronomic textural triangle (clay, sand, and silt) which describes the growth limiting bulk density. a) Soil characteristics are fed to UNSAT-H model which determines the amount of feet needed. b) A variety of soils could work, but as the soil characteristics diverge from the ideal, it takes more soil and at some point it becomes cost prohibitive. c) So the question is, given the nature of the available soils, how thick will the layer have to be to achieve the desired ET result? 6. If Cotter has the appropriate types of soils on site, and ET design might even be less costly, as well as more effective. 7. Next steps. a) Larry will assemble and distribute a bibliography. b) Clint will communicate as needed with Larry regarding the technical aspects of the design. c) Preston will identify and produce a list of potential borrow areas and available soil s data. REMEDIAL SOILS VOLUME (OPA, UNDER CURRENT PLANT, AND WINDBLOWN) Old Ponds Area 1. Cotter has contracted with Paul Rosasco to do an NCP alternatives analysis. 2. Molybdenum criterion will probably be the driver on the amount of soil that needs removal.[jna2] 3. Need to refer to the Hazardous Materials and Waste Management Division s soils policy for guidance. 4. Need to determine [JNA3]if Criterion 6 (6) applies to OPA 5. To better characterize the areas, Preston will drill wells at 250 foot intervals and collect soil samples to 50 foot depths. 6. Roman Pyrih and Bob Moran will be doing analysis of data 7. Kluzman and Colbert are reviewing the data that exists. 8. Steve Landau will ask Paul to prepare descriptions of the alternatives and have Paul make a presentation to CDPHE to get confirmation that the set of alternatives selected are reasonable, and then he can proceed to do the alternatives analysis. Presentation date to be determined after Steve talks to Paul. 9. March 15, a Monday will be the presentation/discussion day for the Pyrih/Moran data analysis and the Rosasco alternatives analysis. 10. The 2.7 million cubic yards estimate will stand until consultant evaluations are available. 11. The Kd term has two meanings: one refers to the material itself and the other refers to the material and fracture context. 12. range of Kd for RESRAD purposes. 13. Suggestion to involve Paul Osborn, EPA, since the OPA is RAP-related and therefore EPA related. Windblown soils Site Decommissioning Team Meeting Minutes 1/13/03 Page 3 of 4

4 1. Characterization data was produced for 1990 plan and also from 1995 Supplemental Health and Human Risk data. 2. This data needs to be verified in two ways. a) Resample a sub area to see if the values are still approximately the same. b) Sample outside the previous perimeters to see if the perimeter has expanded. Soils under the mill buildings 1. Evaluate the area under the CCD tanks. a) Two wells will be drilled to 50 feet, or 10 feet below water table. b) Drilling will produce a continuous core divided into 5 foot sections. c) Cores will be split and ½ saved for later use. d) Samples will be sent to the lab for analysis in stages. e) Water samples will be taken monthly according to the currently approved procedure. f) Cotter will determine the analytical methods and vendors for Thorium-232 decay series. g) RSO instructions to drillers need to refer to applicable SOPs. h) Rock quality designations -- % of core recovered for 5 foot run. 2. There is an elevated reading in an individual well on the northwest a) Is it different in some way from the main ground water path along Sand Creek? b) What is the remedy near the mill site in the NW pathway direction? (Dig up? If So what soil volume?) c) Need to reexamine prior RAP review of Northwest Pathway and determine if the well is on the mill side of the NE pathway divide. 3. Use a Data Quality Objectives (DQO) process in relation to the CCD area characterization. a) What is the vertical extent of soil contamination? b) What is the potentiometric surface in this area? c) What impact on the ground water? IMPOUNDMENT DEWATERING 1. Are there alternative approaches to dewatering? 2. What is a realistic time frame? Lou Miller of MFG estimated three years. A bracketing estimate is 2-5 years. 3. How feasible are techniques and at what point in impoundment closure process? 4. Is there anything that could be done in the next five years to make dewatering more successful? 5. Any further data gathering possible related to overdrains? 6. Would a water balance calculation be useful? 7. Clint will get data from other sites that have been closed and write a paper giving a bracketing to time and cost. Site Decommissioning Team Meeting Minutes 1/13/03 Page 4 of 4

5 Page: 2 [JNA1] This is what Ken wrote. Is the point of the question to determine whether there are methodologies for calculating settlement, and if that is the point, then we need a reference to various methodologies. Page: 3 [JNA2] we should say why. Page: 3 [JNA3] Who/how?