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Lead Service Line Inventory Solution - Arcade Expression

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07-19-2023 12:43 PM
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ChrisMiller_AK
by
Occasional Contributor
‎07-19-2023 12:43 PM

I'm trying to understand how the "assumed lead" category is assigned in the Public Web Map 

The symbology expression is dependent on utilitystatus and custstatus is equal to 1.

What is "1" and where do find this. Is it just saying, "not null"? We can't make the map public if we can't explain it. 🙂 There's really no mention of "assumed lead" categories in the EPA Guidance documentation. Curious what the reasoning was to include this category in the solution. 

"If the value of utilstatus  is equal to 1 and the value of utilsource is "Installation record (e.g., tap card)," or if the value of custstatus is equal to 1 and the value of custsource is "Installation record (e.g., tap card)," then return "Lead."

If the value of utilstatus  is equal to 1 and the value of utilsource is "Water sampling only with no records," or if the value of custstatus is equal to 1 and the value of custsource is "Water sampling only with no records," then return "Lead."

1 Reply
AlexKabak
by Esri Contributor
Esri Contributor
‎07-19-2023 01:29 PM

Hi Chris,

The "1" you reference above is the coded value of "Lead" in the list of values for both the utilstatus and custstatus fields, which are the 2 fields representing the material classification of the utility side and customer side of the line. The utilsource and custsource fields represent the source of information (how the material was determined) of both sides of the service line.

The expression that powers the symbols, specifically the "Lead" and "Assumed Lead" categories, uses the material classification (in this case, Lead) and the source of information to determine whether or not the "Lead" classification is "known" or "assumed". The sources we chose for known are:

  • Installation record (e.g., tap card)
  • Water sampling only with no records
  • Field inspection only with no records
  • Service line repair or replacement record

The sources we chose for assumed are:

  • Statistical analysis
  • Previous materials evaluation
  • Installation date is after the lead ban
  • Service line diameter is greater than 2 inches
  • Other

We added "Assumed Lead" as a category until the material has been verified with one of the "known" values above. Some states may accept some of the "assumed" sources as a means of verification, and in that case the expression can be adjusted.