Using the well interference web application

There are three steps to using the web application:

1. Select the wells
   • Entering Wells
   • Editing Well details
2. Select the parameters and generate the input file (PRN file)
3. Download the WQN10 Program

Step 1

There are three ways to enter one or more wells into the form.

• To enter one well number at a time, the user can enter a well number then click on "add to list".
• To enter all of the well numbers entered against a consent/application number, enter the consent/application number in the field and then click on "add to list".
• If a well doesn't exist on the Wells Database or is not a valid well number, the user can enter a "virtual well".  An Easting, Northing and depth is required, and if a Q7 and Q150 is not entered, then the nominal rate will be used.

This web application links directly to Environment Canterbury's databases so will only accept valid consent numbers and well numbers.  If anything looks incorrect, please contact Customer Services.

If a mistake is made or the user wants to perform a new assessment, pressing the "Reset Form" button will remove the wells from the list and reset the default parameter values.

Figure 1: Step 1 - Add Wells

Editing well details

When assessing a "virtual well" or proposed well, it is possible to edit the details of the well before generating the PRN file by clicking on "edit" next to the well to be altered.  This will not enable the WellNo field. NOTE: This does not effect values in Environment Canterbury's databases.  To change values on Environment Canterbury's databases, please contact Customer Services.

If entering a "Virtual Well" or assessing a well with missing data, it is possible to add values to the PRN file after it has been generated by Step 2 below,  e.g. Top Screen depth, Specific Capacity and CalcMin values which are not specified for a "Virtual Well".

Figure 2: Step 1 – Edit Well details

Step 2

There are several parameters that can be specified by the user at this stage, each has default values entered when the web page loads:

• The depth range of wells to be assessed.  The default values a 0 m to 999 m so that all wells within the specified distance will be assessed.
• The radius of the assessment.  The default is 2000 m.
• Nominal Flow for un-consented wells used for Domestic Supply or Stock water.  The default is 0.12 l/s and will only apply if the Wells Database records the use of the well as Domestic or Stock water supply.

Press the "Generate PRN File" button to create the input file.  This may take up to a couple minutes to generate depending on the connection speed, so please be patient.
A pop-up screen will appear asking where the file should be saved on the user's computer.  The file can be renamed as desired but do not change the extension of the file (".prn").

Figure 3: Step 2 - Set Parameters and generate input file

Step 3

Each time that an assessment is done using this web application a check should be made to see if there is a new version of the WQN10 program available to download.  Check the "About" menu item to see what version is being used.  The program is updated as feedback leads to improvements of the program.

Figure 4: Step 3 - Check for the latest version of the WQN10 Program.

Using the WQN10 program

The stand-alone version of the WQN10 program is very similar to what the Investigating Officers use, except that certain menu items have been disabled as they cannot be used from outside Environment Canterbury.  These menu items relate to creating the PRN input file.

Once an input file has been created, as in Step 1 and 2 above it can be reviewed in Notepad, Microsoft Excel or any other text editor program and modified if necessary.  Please Note: Any manual adjustments to the input file will need to be detailed when presenting the results to the Investigating Officer so the results can be replicated.

To use the WQN10 program there are 6 steps:

1. Open the WQN10 program that you have downloaded, as in Step 3 above.
2. Input the PRN file using the "Load Existing Input.PRN" menu item as shown below. Browse to the downloaded PRN file and open. The wells to assess should appear in the list box on the form. You can modify the data in the PRN file with the Notepad edit option if needed.
   
    
3. Check the data (optional).  The "Data Check" menu has three options.  The first two provide graphs of the screen and depth distribution of the wells available in the PRN file.
   
   
   The "BalT" option will present the following pop-up for each centre (assessed) well.  The T value is an estimated only and is similar to the results of the internal Environment Canterbury TCalc program.
   
    
4. If there are still wells showing drawdown problems with conservative aquifer parameters, then careful further consideration of aquifer parameters, well depths, calculated minimum water levels and screen settings might show that some affected wells are
   • not deep enough,
   • screens are set higher then usual, or
   • the calculated minimum water level is not appropriate for the aquifer. You can set the “adequate penetration depth of aquifer” on the form to a depth that will than be used in the assessment for shallower wells. In some cases, well interference effects can be excluded on the basis of aquitards between wells with different depths, but you have to show with borelogs or aquifer test results that it is likely.
   For shallow aquifers and wells, the default WQN10 screen and pump length are not appropriate. Knowledge of likely pump settings (surface pumps) for these type of wells might lead to setting different pump and screen lengths, but again needs to be justified.
   
   If none of the affected wells can be excluded for the above reasons, well interference effects are likely to occur. It is recommend that an aquifer test is conducted to measure the interference effects and also in cases where the wells aren’t drilled, potential problems can be avoided with shifting the proposed location (change of the bore consent conditions) or screen depth conditions, e.g. when shallow wells would be affected the proposed take can be from a deeper aquifer to avoid affecting the shallow wells.
5. Check that the Use Notifiable Date checkbox is selected.  This will ensure that the analysis only takes into account other applications notified before the notified date of the application containing the assessed wells.  The box below the check box shows the notified date of the assessment wells.  In the below example there is no notified date entered in the Consents Database yet, as such it shows the default value of 1/Jan/1900.
   This can be manually changed on the PRN file if needed.
   
    
6. Run the analysis using the Run WQN10 menu item shown below.  You have two output format options.  Excel spreadsheet is recommended due to the better formatting and as such is easier to read. However, the text file option has been added for those who do not have Microsoft Excel.
    

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