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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00359 | ||
| PWS Name: | CORBETT WATER DISTRICT | ||
| Who Was Contacted and Phone: | Jim Jans (503) 695-2284 | ||
| Contact Date: | 09/03/2013 | ||
| Contacted By: | NUSRALA, JAMES (REGION 1) | ||
| Contact Method/Location: | Office | ||
| Assistance Type: | OTHER REGULATORY - REGULATORY ASSISTANCE | ||
| Reasons: | Operations N/A |
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| Details: | SUMMARY: Clarification of pH readings and calibration status DETAILS: Jim visited the DWS office on 9/3 and clarified via phone on 9/20 the following: 1. At times pH readings after clearwell dropped to below 6. Does not make sense to Jim as pH leaving treatment plant (prior to addition of soda ash) is in the mid 6s. The continuous meter (VCF-100) had been calibrated recently, but he and Hach determined that the meter is malfuntioning as on the spot calibrations wont work. He sends unit back to Hach, and uses a calibrated meter from another location which immediately reads a higher more acceptable pH value. Problem limited to after clearwell, pH meter after reservoir reading levels above minimum required 7.0. 2.) CWD may not be calibrating NTU meters exactly quarterly, and given concerns about pH readings, CWD will contract out with Hach to calibrate all NTU and pH meters. ACTION NEEDED: I clarified with Jim the following: 1.) Calibrate all NTU meters quarterly, and follow manufacturers requirements on calibrating continuous pH and chlorine analyzers, 2.) Correlate on-line chlorine analyzers weekly with calibrated hand device. Jim indicated Hach is calibrating all continuous NTU (1720-Es) and pH meters quarterly, CWD calibrates CL-17s monthly, and correlates CL-17s weekly with hand device. I clarified required the minimum required 7.0 pH and min. 8.0 alkalinity after reservoir (entry point) for corrosion control, based on average of continuous daily data for compliance. | ||