Field Office Compliance - Assistance

Assistance ID - 104498
Des Moines Water Works - 310338211
9966 Maffitt Lake Dr Cumming, IA 50061
Dallas County

FO 5

Report
File Name File Type File Date Note
Comments
12/20/2018 Woodruff, Carter 1:03 PM (2 hours ago) to me, Kyle, Mike Thank you Janet. We will have someone look into the pass/fail criteria and verify calibration using the 20 NTU ICE-PIC as well. JANET GASTINEAU
12/20/2018 From: Gastineau, Janet [mailto:[email protected]] Sent: Thursday, December 20, 2018 12:54 PM To: Danley, Kyle; Woodruff, Carter; Adams, Mike Subject: follow up One staff person suggested making sure the controller has the right pass/fail criteria set. You can do this manually based on the regulatory requirements. This information is not necessarily in the 1720 series manual, but he found it on the internet. A good ver may be reported if the pass/fail is set for more than 10 percent, for example. He also added multiple turbidimeters will give different reference values on the same ice-pic, which is frustrating, but manageable as long as the correct value is used for each turbidimeter for each verification. "The 1720E is based on US EPA methods (180.1) and this is the requirement in the method. A Primary Standard is a liquid calibration with Stablcal or Formazine. The liquid standard can also be used as a wet verification or we offer the Ice-Pic for a dry verification. The dry verification is considered a Secondary standard and should not be used for a Primary calibration if you are reporting to a regulatory agency. When you calibrate with the Primary Standard, the 1720E will offer a chance for a dry verification. If done then, this will set a "baseline" reading in the Ice-Pic which can be used as often as you wish to see if the calibration is holding. You can set the pass/fail criteria for the dry verification between 5-10% depending on your own quality procedures. If you do a dry verification and it fails, that would indicate you need to do a Primary calibration and then a new dry verification to reset the "baseline" reading, Refer to your instrument manual for further details. We also state that you should always check with your local regulator as they may have more calibration requirements." JANET GASTINEAU
12/20/2018 On Thu, Dec 20, 2018 at 10:12 AM Gastineau, Janet <[email protected]> wrote: Good morning! A few questions for you based on a conference call Mark and I had this morning with Des Moines Water Works. In your experience, 1. If using a 20 NTU primary standard for calibrating 1720 series turbidimeters, should a 20 NTU ICE-PIC be used or one closer to the typical turbidity being measured by the unit? 2. Of the systems you have that have begun calibration verifications using Hach ICE-PIC, have they expressed any problems getting the ICE-PIC to be within 10% of the initial/reference values, but the controller is still reporting a good verification? 3. What method of calibration verifications do you see your systems using? Des Moines WW is working closely with Hach to try to settle some of the problems they have been having, which include ICE-PIC not being w/i 10% of reference values even after a recalibration. They calibrate with 20 NTU primary standard but Hach recommended a 1 NTU ICE-PIC. They've looked at the turbidimeter "gain" and in at least one case replaced a light bulb but no change. DMWW is going to host a meeting with Hach and DNR to try to remedy the problems, which are bound to pop up as we move toward enforcement of calibration verifications. Aaron, we would like you there in person or by phone. It won't be until after January 7, so I'll let you know. Please share any experience you have with systems practicing verifications. Thanks! JANET GASTINEAU
State of Iowa DNR Home Site Policy
Leading Iowans in caring for our natural resources
Version: 2.3.1.23706
"
"