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pH and Hardness dependant criteria for metals
Rank: Administration
Groups: Registered, Administrators Posts: 498 Location: Byron Bay Was thanked: 19 time(s) in 19 post(s)
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Hello all users, especially those in Canada. In BC and Alberta in particular the guidlines for metals indicate different acceptable trigger levels based on the pH, temperature, hardness and sometimes other parameters. Currently, the guidelines compiled for ESdat have used the most conservative trigger level as the default, with a comment indicating that exceedances may be re-evaluated based on the trigger level that may apply for the pH, temperature etc... We are interested in peoples thoughts on other possible approaches. Currently options seem to be: - Add functionality to allow comparison on a per sample basis, so that chemistry tables can cross-reference the pH, temperature for each sample and format each metal result individually.
- Create a post-import custom calculation (functionality already available) for ESdat that automatically provides a single trigger level for that site based on either the average or log average of the pH, temperature etc...
Our thoughts are that the first option has issues related to user transparency, and technical implementation, and that the second approach is both more feasible and more transparent. Any user thoughts on this, the general preference of using a site averaged pH, temperature etc.. rather than for each sample, and any other preferred approaches would be much appreciated. Sincerely, Warwick
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Rank: Member
Groups: Registered
Posts: 14 Location: Vancouver
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With respect to your second option, it is not applicable in BC. That is cut and dried. You cannot average pH or hardness for a site and use that to apply a blanket standard. The standards apply on a per sample basis. Full stop. If you have one sample that fails it's pH or harndess dependant standard, you are done. The regulators do not accept averaging of the dependant factors as an approach. For BC, option 1 is the only choice. Thank you for considering these options.
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Rank: Administration
Groups: Registered, Administrators Posts: 498 Location: Byron Bay Was thanked: 19 time(s) in 19 post(s)
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Thanks for your insights on that. One other approach may be to select the most conservative criteria value based on the pH, temperature values over the whole site. That would also be transparent and relatively easy. I'm not sure though if that would be considered a significant advancement over the current method of selecting the most conservative value for all pH etc.. conditions. Regards, Warwick
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Rank: Member
Groups: Registered
Posts: 14 Location: Vancouver
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I'm afraid that for BC, there is no way around the sample specific standard approach. We simply do not blanket a site with an overall standard when they are sample specific. Yes, that does mean that you could have 50 samples on one site an only one of them fails, but that also means that you only have one sample on your site that has to be remediated, not the whole site. The words BC Regulations and easy or transparent simply do not go together. We live with this every day.
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Rank: Newbie
Groups: Registered
Posts: 21 Location: EBA Engineering
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In Alberta, we'd take the most conservative pH and hardness and apply it to the site (or individual aquifer). We were thinking here that a flag could show in the output tables guidelines column (-999999), then the user would have to manually fill.
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Rank: Administration
Groups: Registered, Administrators Posts: 498 Location: Byron Bay Was thanked: 19 time(s) in 19 post(s)
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Hi Ryan, The current compilations use the most conservative value (irrespective of pH etc..) as the default value, and have a comment indicating that higher trigger values may be applicable depending on the pH etc.. If you select the "Comments" checkbox in Environmental standards prior to producing the table then you should see this comment in the output table. Is that suitable as a "Flag" for your needs? In any case I'd recommend changing the value in the zRef_Environmental_Standards table in the database, rather than in the output tables, then regenerating them, otherwise you have to remember to change the output every time you produce the table. Regards, Warwick
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Rank: Newbie
Groups: Registered
Posts: 21 Location: EBA Engineering
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Yeah that could work. The only problem is with multiple people at multiple times printing off the chemistry table. Down the road, someone outputs the table without that knowledge while assuming the data set is complete, a guideline might get missed. That's why I like the -99999 or &^%$* idea.
The zRef_Environmental_Standards change would work possibly. Can only DBO's do this?
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Rank: Newbie
Groups: Registered
Posts: 0 Location: Vancouver
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Hey Warwick, Yes, I think the way to go would be to check pH/Hardness of all samples for the sampling round, and then pull out the lowest applicable standard based on sampling round results, with a note in the comments. Ideally, it would be great to show a range (ie: for Zinc: 150 - 350, with a note in the comments). Or, not sure if this is doable, but have multiple rows made for each compound with a pH / hardess dependant standard, with each row having a different value along with the corresponding pH / hardness value (ie: 1st row: 150 @ pH <6.5, 2nd row: 300 @pH<7.0 etc...) or split up the standard and the corresponding pH into different columns, calling one Environmental Standards, and the other "Trigger pH value" or something like that.... Just a couple thoughts. Thanks.
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Rank: Newbie
Groups: Registered
Posts: 10
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I would prefer option 1 for the Yukon standards. Although the concern may be transparency, it should be coveren in the QC phase that we carry out and deptails on the ranges can be noted in the footnote section of the output.
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Rank: Administration
Groups: Registered, Administrators Posts: 259 Location: Ballina
Was thanked: 8 time(s) in 8 post(s)
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Hello, An update to BC Sch 5 (which has pH dependant values) has been uploaded to the web site. Future compilations will be using, and building on, the same approach. It allows users to specify the expected pH range across the site, and guideline values are chosen based on the range. The logic is all contained in Excel formulaes, so is easy to customise if need be. Comments are also generated for each guideline indicating the pH range used for selecting a particular value. Comments on this approach are very welcome, but we have decided that having varying guideline values for different pH values on a sample by sample basis is difficult to display visually (and transparently) on a single Chemistry Table, as well as being difficult to audit. Therefore exceedances of the "Conservative" values for a pH/hardness range will be flagged. These can be un-flagged manually where that is appropiate. If you are using a regulatory guideline that is either not compiled (by us) for use through ESdat, or you would like updated to the new approach please send the guideline through. Sincerly, Alex
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