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This page contains answers to common questions asked during beta testing, along with some tips and tricks that we have found useful and presented here as questions.


Why do productivities and total costs change when I import data into a clean model?

Bug fixes and modifications to the model may rarely result in different costs and productivities with the same input data for specfic modules. However, it is more likely that there are a few user selected settings that are not the same in both models. Here are three steps to checking these settings:

  1. In the Fleets/Crews sheet, check all of the fleet settings to make sure they were imported properly from the original model. If not, manually set them to the correct settings. In versions prior to 1.4.011 this might require changing the fleets to different equipment and then resetting them to the correct equipment.
  2. In the Productivity sheet check the job and operator correction factors at the top of the sheet to make sure they are the same in both models.
  3. If your original model included adjustments to the Altitude Deration table at the bottom of the Productivity sheet, you will need to make these adjustments manually to the new model.
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Is the model compatible with Excel 2010?

Yes, beginning with Version 1.4 all model development was done in Excel 2007. Version 1.4.1 has also been tested in Excel 2010 and actually runs better in that version of Excel. There are a few quirks in Excel 2007 that have been fixed in Excel 2010.

Version 1.1.2 will also run in Excel 2010. Follow the instructions located here.

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Is Version 1.4.1 compatible with Excel 2003?

No, beginning with Version 1.4 all model development was done in Excel 2007 and it is no longer compatible with Excel 2003.

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The macros aren't working and I didn't see the slash screen.

See the Excel 2007 Security Tip or the Excel 2010 Security Tip for instructions on setting and editing security settings to allow the Model to run in Excel 2007 or Excel 2010, respectively.

If you are using Excel 2007 and still have problems, it may be a windows problem that is discussed on the FAQ below. In that FAQ there is a link to a program that will override some of the macro security in Office 2007. This may be against your corporate IT policies, so be careful. We have also heard that Service Pack 2 may also fix this problem, but we have not tested that.

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When importing a previous model I receive a message that says the it is not a valid model file. What is the problem?

There are four possible reasons why this message may appear:

1) The file you are trying to import is not a SRCE model.

2) You are trying to load a new version of the SRCE into an older model version.

3) You are working in Excel 2010 and trying to import an Excel 97-2003 model, which has some security issues that will not allow the import routine to run without preparing the import file. See the Importing Excel 2003 Model Files into Excel 2010 Tip for instructions.

4) Some of the worksheets in the model you are trying to import are grouped. Follow the instructions below if you don't know how to ungroup worksheets.

If any of worksheets in the file to be imported were grouped when the file was last opened (e.g. for printing multiple sheets), the file may have been saved them with them grouped. If so, the import routine cannot import the file into a new model. You will have to ungroup the worksheets and save the file again before it can be imported.

You can tell if the worksheets are grouped by looking at the worksheet tabs at the bottom of the screen. If any of them are grouped, they will be a lighter color than ungrouped ones. 

To ungroup the worksheets, select the tab of one of the grouped worksheets and click the right mouse button. Select Ungroup on the menu that appears.

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Is the Nevada Version of the Model compatible with Excel 2007?

Yes. The model will run in the Compatibility Mode of Excel 2007 or you can save it as a Macro-Enabled Workbook that is fully compatible with Excel 2007. The Compatibility Mode in Excel 2007 allows you to run spreadsheets developed for earlier versions of Excel. However, there are a number of limitations with the Compatibility Mode and the full capabilities of 2007 are only available in an Excel 2007 spreadsheet. Converting the file to an Excel 2007 file is generally a better alternative.

To create an Excel 2007 version of the Model open it in Compatibility Mode and then use the Save As option and save it as an Excel Macro-Enabled Workbook (*.xlsm) file. We are in the process of testing a fully compatible Excel 2007 version. You should now close the file and reopen the new *.xlsm file.

Note: If you are running Excel 2007 you may run into a problem with the VBA macros that make the model work if you are running it on a computer with the Windows XP operating system. This is because Microsoft has significantly increased the security in Office 2007. According to the Microsoft website, Windows XP should work just fine, but when you set the Trust settings to allow signed macros to run, Excel 2007 will still not allow them to run. According to Microsoft this is because you do not have Antivirus software installed that is compatible with the Microsoft Anti-virus API. We have tested this with all of the standard antivirus software packages, so we know this is not the problem. This problem does not exist on computers running Windows Vista. To those of you who are conspiracy theorists, this might sound like Microsoft is just using this as another way to get all of us to switch to Vista. At the moment, we have not intention of doing so.

The good news is that there is a work around. We found a website that addresses this issue and has a link to a registry hack that will make necessary changes to your registry file without jeopardizing Excel security.


According to their site…  “This registry change does not compromise the Excel 2007 security in any way. It only allows macros to run in protected files that are saved in the new Excel 2007 Open XML file format. (If you are using Windows Vista and have anti-virus software that complies with the new Microsoft Anti-virus API, you should not need this registry modification.) You can modify your macro security settings in Excel 2007 by clicking on the Excel 2007 Office Button in the upper left hand corner of the screen and clicking the Excel Options button. Then click the Trust Center button in the left pane and click the Trust Center Settings... button and click the Macro Settings button in the left pane. In the Macro Settings section, we recommend using either the "Disable all macros with notification" or the "Disable all macros except digitally signed macros" option.”

We have installed this patch on two computers and it does solve the problem. We have not noted any issues with security or anything else. However, the authors of the NVBond.org website do not guarantee or warranty that software, so you use it at your own risk.

We have also run into the following error message when starting the Model in Excel 2007 if Active X controls even after setting up the Trust Center to allow macros from Trusted publishers:

If this dialog box appears, you probably have the following message displayed on the bottom of the Ribbon:

If this message appears, click on the Options... button and the following dialog box will occur. When it does click on the "Enable this content" radio button and then on the "OK" button.

This should then allow the model to run unhindered. However, we have found that the graphics on some of the sheets will not move with the cells where they were placed and may cover some of your data tables. We are searching for a the source of the problem and a cure. When we have this problem sorted out we will release an Excel 2007 version of model.

For more information, download the SRCE Tip Sheet here.

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What is the difference  between Version 1.1.1 and 1.1.2?

The only difference between Version 1.1.1 and Version 1.1.2 are changes to Operator correction factors used in productivity calculations for some of the equipment types used in the model. These changes are shown below. No other changes, bug fixes or improvements were made in this version.

Equipment Type Version 1.1.1 Version 1.1.2



















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Will the Well Abandonment module ever return?

Yes. The Well Abandonment module originally included in Version 1.0 has been updated based on a significant amount of field data from well abandonment work performed over the last few years. When a new version (after Version 1.1.2) is released, this module should be included once again.

The timing of the release of another version validated for use in the State of Nevada that includes the Well Abandonment module will depend on the review process that all model changes must undergo for approval by the NDEP, BLM and Industry. A version containing the Well Abandonment module may be released earlier in an international version (metric) of the model. However, until that version undergoes the verification process dictated by the Nevada Standard Unit Cost Project, it will not be approved for use in calculating bond costs in the State of Nevada. 

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What is the difference  between Version 1.1 and 1.1.1?

Version 1.1.1 is a minor update of Version 1.1 that contains a few bug fixes that were deemed significant enough to justify an interim release. This is the version that should be used for bond calculations in the State of Nevada after November 1, 2006. 

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What is the security warning message that comes up when I load the model?

When you load the model for the first time, you should see a security warning dialog box appear. This lets you know that the file contains macros and give you the option to verify that the code comes from a publisher with a valid code signing certificate. A code signing certificate is verified digital signature that ensures that any code (programs) or macros are published by a person or company registered with an internet code certifying organization. The code written for the SRCE was written and signed using this type of signature to protect users from forged versions that could contain malicious software code.

screenshot sample

The first time you load SRCE model you should see a dialog box looks like the one above. This gives you an option to review the certificate and then enable the macros contained in the SRCE. You must do this for the model to work properly. You can avoid having to accept the code signature each time you open the program by checking the box that says  "Always trust macros from this publisher".

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How do I load cost data into the SRCE model?

Cost data is imported into the SRCE model using the "Import Cost Data" option from the custom SRCE Menu. If the cost data file changes, you will need to re-load the cost data to update the model.

The data must be in the exact format contained in the user cost data file (Cost Data USR.xls) file available from the Downloads page of this web site or a standardized cost data file available from your local regulatory agency. Links to some of these regulatory web sites are also listed on the Downloads page of this web site.

The standardized versions of the cost data file are locked and cannot be edited by the user. These files are typically maintained and updated by regulatory agencies responsible for reviewing and approving reclamation cost estimates for financial surety purposes. The cost data cells in the user cost data file are unlocked to allow users to enter their own cost data (e.g. mine costs). 

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I get an error message telling me that the cost data file I am trying to load is not valid.

When you try to load cost data from a data file you see the following message:

This error message appears when you try to import a cost data file that is not in the correct format. Because of changes that may occur from one Model version to the next, the format of the cost data files may also change.

For use with Version 1.1 or 1.1.1 of the model you need to use a version 1.4 cost data file. The standardized Nevada cost data cost_data-std-nv2006.xls can be downloaded at the NDEP website. For a user editable version 1.4 cost data file, go to the Downloads page on this site.

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Where can I find standardized data for my area?

Typically, if the regulatory agency responsible for reviewing and approving reclamation cost estimates for financial surety purposes in your area has adopted the Nevada SRCE as an acceptable reclamation cost estimating method for your area, they should have an area-specific version of the standardized cost data file available on their web site.

We will attempt to keep an up-to-date list of links to regulatory agency websites that contain standardized data files, but contact your regulatory agency if you do not find a link for your area on the Downloads page of this web site. If an agency requests that a copy of the file be stored on this site you will be able to find it on the Downloads page of this web site.

If your local regulatory agency has not created a standardized data file, you can use the user cost data file (Cost Data USR.xls) file available from the Downloads page of this web site to input your own cost data into the model.

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What do the different colored cells mean?

Cells formatted for user input are colored green, cyan and yellow. All other cells are locked and cannot be accessed by the user. The only exception to this are the User sheets, which are unlocked to allow user input and formatting to all cells except the headers.


Green cells are formatted for direct input.



Cyan cells contain drop-down lists that allow the user to select from a list of valid options.



Yellow cells are used for direct user input that overrides calculated values for earthwork volumes or areas (i.e. regrade volumes or areas for revegetation).



Where appropriate, data entry tips are provided when a cell is selected.



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How accurate is the SRCE model?

Like any computer model, the accuracy of the SRCE is directly affected by two factors:

  •   The assumptions and methods used in the model; and

  •   The data input by the user.

To the degree possible, we have attempted to provide references, figures and footnotes in the model to describe the assumptions and methods used in the calculations. A technical reference manual that will further detail the methods is in production.

The input provided by the user will have a significant effect on the accuracy of any reclamation cost estimate generated by the model. The basic philosophy used in developing the model assumed that the user would have a basic working knowledge of reclamation cost estimation techniques along with an accurate description of the facilities, a good topographic map of the project and an engineering scale. The user should be able to generate all of the required input using these items. Other methods including CAD, GIS, and engineering software can also be used to prepare the user input data. 

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How does the SRCE model determine the number of trucks or loaders needed?

The number of scrapers or trucks required to efficiently move cover material or topsoil is calculated based on the time required to fill each truck/scraper and the cycle time for each truck/scraper (i.e. time required for each truck or scraper to make a round trip to/from the borrow source to the facility to be covered). The number of trucks or scrapers is then optimized based on the the time required to load each truck/scraper, a method referred to as loader-limited or dozer-limited. In other words, the model assumes that there will always be a truck/scraper ready to be loaded as soon as the previous one is loaded.

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Is there a metric version of the SRCE model?

Not yet, but the primary development goal of version 1.1 is the ability to use either English or metric units. This version is scheduled for release in March 2006. Keep checking the What's New page for updates

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How was the SRCE model tested?

Testing of the model was performed first by the primary developers using hypothetical and actual data from real mine sites (alpha testing). Model results using real mine sites were compared to other methods. After initial testing, two separate beta test versions were distributed to state and regulatory agencies, mine operators, and the public for further testing.

Throughout the alpha and beta testing processes, comments were compiled and, as necessary, changes were made to the next version of the model. Version 1.0 represents the first official public release of the model and is, in effect, the first field trial of the model.

While it would be nice to think that we have found most of the bugs and thought of most of the features that the model should include, we are more realistic that that. First of all, there is already a list of features to be included in future releases. We will include those as soon as we can get around to it. Second, we expect the users in the field to think of things we didn't and find bugs we missed. Basically, we assume that this model will always be a work in progress.

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Why are the numbers slightly different when I check the model with a calculator?

Rounding. The Nevada SRCE working group determined defined the criteria for rounding of number in the model. This option in Microsoft Excel is implemented by using the Round function [Round(number, n) where n = the number of decimal places]. All calculations in the model are performed using the default rounding (none) until one of the a final number is calculated.

For the final numbers used in the model, the working group set the following rounding criteria:

Item  # of decimal points

lengths (ft or m)


volumes (ft3, yd3 m3)


areas (acres, hectares)


areas (ft2, m2)




money ($, other)



When the total hours required to haul and place cover are calculated, the initial calculations (cycle times, maneuvering times, etc.) are performed using no rounding. When these interim calculations are used to calculate the final number of hours is calculated, the number of hours is rounded to one decimal point.

 When the number of hours is then used to calculate the labor and equipment costs, the final cost calculation is rounded to the nearest unit (e.g. dollar).

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Why are the areas calculated in the model slightly larger than what I measure on a map?

The model needs to determine surface area (i.e. the area of the non-planar surface) of a facility to accurately estimate cover and revegetation areas. A map area (or footprint area) is the horizontal projection of a facility. Therefore, if a facility has sloped areas (e.g. a waste rock dump), the actual surface area will be slightly larger than the horizontal projection, or map area of a facility. The amount of the difference is determined by the angle of the sloped portion. The greater the slope angle, the larger the difference.

In the waste rock dump and heap leach modules, the model asks for a final footprint area in the user input because it uses that information along with the horizontal projection (footprint) of the slope area to determine the amount of flat area in the final configuration. The footprint of the slope area is not displayed anywhere in the output.

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The StdRecCost menu disappeared from my menu bar in Excel. How do I get it back?

If you open more than one copy of the model at a time and then close one, the StdRecCost menu option at the top of the Excel screen will disappear. To get it back, go to the Macros option on the Tools menu.

This will open another dialog box that will contain at least two macro names.

Select MakeBondMenuBar from the macro list and the StdRecCost menu option should reappear on the Excel menu.

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Is there a method for estimating the cost of pit backfill?

In Version 1.0, not directly. However, you can use the Yards sheet to provide a reasonable estimate. If the backfilling will be performed by regrading the pit walls, you can use the direct input for the volume of the backfill. However, if the backfill will be hauled with trucks, you can estimate the costs by using the cover section. Because the costs estimated for this section are based on hauling material from one location to another, using this for hauled backfill should give reasonably accurate costs. Unfortunately, you need to vary the thickness until you get the volume calculated on the Cover and Growth Media Cost table.

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Jeffrey V. Parshley. All Rights Reserved.