Cost (& Time) optimization of hydrogeological studies

Impact on groundwater flow from mining facilities could be evaluated many times along the different mining phases, many of these evaluations are done by different consultant companies. This post is focused on strategies and best practices for cost (& time) optimization, specially for hydrogeological investigation on mining projects. 

 

Presentation Transcript

1. Cost (& Time) Optimizationof Hydrogeological Studies By:Saul Montoya M.Sc.March 2013

2. This presentation is focused on: Strategies and best practices for cost(& time) optimization. Specially for hydrogeologicalinvestigation on mining projects

3. Mining Hydrogeology Currently mining projects has to fulfill a series of hydrogeological investigation along the mine life. Increasing concern about the environmental impacts. Hydrogeological investigations and numericalmodeling has to simulate, prevent and remediate the mining impact to groundwater system andsurface water courses.

4. Mining Hydrogeology There is continuity on the hydrogeological investigations. Results from the assessment from one mine stage (feasibility) became an input for the next stage. Source: Australian Government, Department of Resources, Energy and Tourism (2008)

5. Mining Hydrogeology Impact on the groundwater flow from mining facilities could be evaluated many times along the different mining phases. Many of these evaluation are done by different consultant companies. Sometimes two companies investigate the same impact at the same time. Challenge: Decrease the double effort!

6. Das Ziel (the objective)

7. Water Management in Mining Water management in mining objectives are: • Assess all relevant aspects relevant to water extraction, treatment, use and preservation. • Indentify all current and potential risks to natural water bodies from the mining activity. • Simulate and evaluate the impact from the mine water use to the other water users.

8. Water Management in Mining Water management plan characteristics: • Water-quality and water-quantity integration. • Incorporates site general hydrological conditions. • Has a detailed plan with responsibles and calendars. • Plans with quantitative objectives rather than subjective objective. • Has reports, operation procedures, and manuals. • It is dynamic, regularly rewieved and updated.

9. Main Hydrogeological Investigation in Mining

10. Mine Project Development • Baseline investigation on groundwater/surfacewater flow regimes. • Monitoring network design. • Groundwater impact assessment (quality andquantity) due to the mining project. • Mine water supply evaluation. • Pit inflows and mine drainage evaluation. • Predictive simulation of groundwater flow regime on mine closure.

11. Mine Life • Water resources database management system implementation. • Surface water/groundwater monitoring system upgrade. • Pit inflow/mine drainage modeling update. • Contaminant transport modeling from waste dumps and tailings deposits. • Upgrade of groundwater numerical models andresimulation of project impact. • Predictive simulation of groundwater flow regime on mine closure. • Rules for site potential contaminant release.

12. Mine Closure • Water balance on closure conditions. • Assessment of the pit lake flooding time, final level and water quality. • Review of contaminant transport modeling on closure conditions (Validation/Optimization). • Evaluation of natural attenuation on contaminant transport evaluation. • Design of remediation plans.

13. Das dinge an sich (Kant)The thing in itself

14. The thing in itself Plan, plan and plan!

15. The thing in itself “Begin with end in mind” Habit 2 from the book “The 7 Habits Of Highly Effective People” from Stephen R. Covey Before spending hours in any task one has to understand why the task is being conducted and how it helps to meet the project need.

16. The thing in itself For cost optimization, you have to do the minimum required to effectively accomplish the goal you need to reach. In the end, it's highly about money, money, money!

17. The thing in itself Take into consideration these Bottle-necks: - Travel and transportation times - Seasonal restrictions - Personnel disponibility - Problems with communities - Security protocols, and many more… Bottle-necks are simple to remove after they are identified.

18. The thing in itself Dont be too optimistic about your times and budgets.Once a contract is signed, it becomes very difficult to change the hydrogeological study scope or to ask for money and time. Insufficient planning and failed attempts to minimize costs led to effort duplication later on.

19. The thing in itself "If anything can go wrong, it will.“ Murphys law

20. First Step: Conceptual Modeling

21. Conceptual Modeling Conceptual modeling is the first step on the hydrogeological investigations.The conceptual model is the degree ofunderstanding of the groundwater flow regime withthe available information.If the hydrogeological conceptual model (and thegeological conceptual model) are flawed everythingelse is flawed – design of the groundwater flowregime.

22. Conceptual Modeling We can have a reasonable from a site and data with good background on hydrogeology:

23. “Hydrical Eye” What everybody see versus what a hydrogeologist see. Cuenca, Manantiales y Bofedales Ancash Springs Wetlands Precipitation as Snow Natural Drains Fuente: Trekearth.com

24. Conceptual Modeling Conceptual modeling is a tool. One have to build, review and improve it. A reasonable conceptual model from the beginning helps focus on what data is most critical. All phases of the hydrogeological investigation will update the conceptual model.

25. Conceptual Modeling Conceptual model will optimise well locations and inform the understanding of aquifer interactions. It is good to use the results of previous studies abasis for the investigation phases. The conceptual model is then “translated” to the numerical model.

26. Conceptual Modeling Groundwater flow is spatially distributed, therefore you should build your conceptual model with GIStools (If you dont want to mess around with abunch of maps and reports). Save the trees!

27. Einige Empfehlungen (some recomendations)

28. Field Investigation

29. Field Investigation Seek for the opinion of a specialized group of people early on the mine planning. Coordinate geotechnical and hydrogeological studies. Both tasks can collaborate on the drilling and characterization efforts.

30. Field Investigation Why dont you install a piezometer on every geotechnical drilling? It might be not suitable for groundwater quality monitoring but it's okay for water levels and hydraulic tests. Baseline soil chemistry can be done at the same time too. This information is also very important for mine closure to show original soils quality versus post-operational phase chemistry.

31. Monitoring Network

32. Monitoring Network A minimum of 30 piezometers is required to have a normal distribution of water heads. However, amining proyect in its early stages has fewer points. An optimized approach is to couple piezometricdata with baseflow gauging.This is a recommedation from the commonpractice: a monitoring network of 12 piezometers (>30 m) plus 5 baseflow measurements will be enough to give a good understanding of the groundwater flow regime.

33. Monitoring Network Groundwater levels and baseflow variation. How is the correlation with depth of installation. Source: DCNR

34. Monitoring Network However, the number of piezometers depends on scale of the development and complexity of groundwater regime. Mining project/consultants in Peru usually budget from 8 to 12 piezometers that is limited to understand the groundwater flow regime. If modellers ask for 30, there will be more chance to get 18 points.The bigger the water level/baseflow monitoring network, the better understanding of thegroundwater flow regime.

35. Multilevel Piezometers Multilevel piezometers can describe different piezometric level with levels at one location.These piezometers can give useful information about an isotrophy, hydralic parameters and recharge mechanisms. Multilevel piezometer has not much value without multilevel readings with time (minimum one year). Source: Solinst

36. Multilevel Piezometers Multilevel reading requiere a more detailed numerical modeling with transient calibration. Better estimation of K, Sy and Ss. If you plan to deliver a report in 6 months, it is better to use one level piezometers. Source: Solinst

37. Field Sampling

38. Field Sampling Do a lot of sampling on the early stages of your hydrological investigation. Analyze the spatial and temporal variability of groundwater levels and quality. Then optimize your piezometric network!

39. Field Sampling Dynamic of monitoring networks

40. Field Sampling Nobody has a university degree to: • Sample groundwater levels. • Measure groundwater ph, conductance and temperature. • Use a flow meter, or reading a water scale. Hire local capacity!

41. Field Sampling

42. Field Sampling There is balance in between the water level sampling frecuency and error on the measurement.The lower the cost, the higher the error.

43. Pumping Tests

44. Pumping Tests Usually one has to quote supervisors 24 hours, plus a generator in backup. High uncertainty on the results and interpretation if pumping is interrupted.

45. Pumping Tests Graphical interpretation of pumping test comes from the 70’s were computational power was scarce. Software for pumping test interpretation do not take into account anysotropy, incontinuos layering and varying pumping schedule.

46. Pumping Tests Pumping test interpretation with numerical modeling gives you flexibility to: • Turn on, turn off, increase/decrease pumping rates several times as long as you record the pumping schedule and rate. • Only need an operator to fuel the generator.… that decreases the cost of the pumping test!

47. Pumping Tests Nowadays submersible pumps are moreslim.2” submersible pumps can perform pumpingtests on 4” piezometers… that increases the availability of the pumping locations!

48. Die Helden (The Heroes): Groundwater Numerical Models

49. Numerical Modeling Groundwater numerical models are not a “trendy”, “stylish” or “fashionable” part of the hydrogeological report.Groundwater model are the best tools available to understand the fate and transport of the groundwater flow regime. We have to see groundwater models as a management tool.

50. Numerical Modeling Determine the need for numerical modeling. Select the right code to fulfill the investigation objectives. Specify the level of detail of the numerical model Compile all relevant data before detailed modeling.

51. Numerical Modeling Numerical models need a good conceptual foundation. Otherwise numerical model becomes a “black box” bringing “rubbish” water head and concentrations that looks great on maps and cross sections.

52. Numerical Modeling Usual hydrogeological study secuence: Optimized hydrogeological study secuence: Data Compilation Field Investigation Data Analysis Numerical Modeling Impact Evaluation Data Compilation Coarse Numerical Modeling Field Investigation Data Analysis Fine Numerical Modeling Impact Evaluation

53. Numerical Modeling Advantaje of the optimized hydrogeological study secuence: • Coarse numerical modeling strength the conceptual modeling. • More flexibility to identify “hotspots” in the area ofstudy. • Optimization of the drilling program. • More time for data analysis.

54. Der Anschluss (The Continuity) on Hydrogeological Studies

55. Continuity When working with data these are the percetanges of time spent on related tasks: Data compilation can be reduced to 15 % if there is a continuity on the staff related to the investigation and the implementation of DBMS (Data Base Management Systems).… that means a time saving of 25 % on the cabinett asks. Data Compilation 40 % Data Analysis 20 % Numerical Modeling 40 %

56. Continuity We have to assure the quality of the hydrogeological studies. Background knowledge is critical to supervise the work of consultants, field monitoring staff and even reviewers. Change of consultants only good practice when the produced studies do not fit the regulatory official requirements. Never change of consultants without a good reason, since there will be a “gap” on the data and the conceptual model… that means more time consumed.

57. Continuity For cost optimization, the consultant company that runs a regional model should be the same the one in charge of the local numerical modeling (tailings dam, pit). Many consultant companies running modeling work on parallel mostly turn on effort duplication, low comunication and different approaches of the groundwater flow regime.… but why?

58. Continuity The Unknown As we know, There are known knowns.There are things we know we know. We also know There are known unknowns.That is to say We know there are some things We do not know. But there are also unknown unknowns, The ones we dont know We dont know.D.H. Rumsfeld, Feb. 12, 2002, Department of Defense news briefing

59. Continuity Numerical models are a interpretation of the groundwater flow regimen based on the available data. Numerical modelers are water resources specialist which “translate” the general aspects of the groundwater flow regime into a numerical code. Never two modelers will produce the same model with same data set.

60. Continuity It will the same as asking two painters to paint the same Mona Lisa.

61. Open source software

62. Hydrologeology Software MS MS EXCEL is an excelent spreadsheet, But.. It is not a safe way store data. It not a efficient way to retrieve data. Do not allow effective collaboration of multiple partners. Cannot be called a data base, it is just a place were your data “is”.

63. Hydrologeology Software Challenge: To migrate the data analysis with MS Excel to different tool in GIS, numerical modeling, Python and DBMS. There is a full set of open source, high performance software for hydrogeological studies. If you want to reduce costs, why do you use commercial software?

64. Draft Sight Draft Sight lets professional CAD users, students and educators create, edit and view DWG files. Draft Sight runs on Windows®, Mac® and Linux. DraftSight is a drafting automation software tool. A coordinate system determines each point of a drawing surface or entity unambiguously. http://www.3ds.com/products/draftsight/overview/

65. Quantum GISQuantum GIS (QGIS) is a user friendly Open Source Geographic Information System (GIS) licensed under the GNU General Public License. QGIS is an official project of the Open Source Geospatial Foundation (OSGeo). It runs on Linux, Unix, Mac OSX, Windows and Android and supports numerous vector, raster, and database formats and functionalities. http://www.qgis.org

66. Quantum GISQuantum GIS provides a continously growing number ofcapabilities provided by core functions and plugins. Youcan visualize, manage, edit, analyse data, and composeprintable maps.

67. MODFLOW MODFLOW is the software for groundwater modeling developed by the USGS.The software is capable to represent conditions related to the groundwater flow as evapotranspiration, recharge, drainage, river interaction among others .http:///en/infohatari/learn-modflow-model-muse

68. MODFLOWIts finite different approach gives the capability to calculate the flow regime with exceptional control on the water budget discrepancy. With MODFLOW one can rely that the flow that is going in the model is the same that the flow going out of the model, from the regional scale and oncross sections.

69. Special thanks for his collaboration on this presentation: Dr. Campbell G. FlemingTechnical Director Enviro Centre Limited

70. Habt Iht Fragen? Do you have questions?

71. Cost (& Time) Optimizationof Hydrogeological Studies By: Saul Montoya M. Sc. March 2013