OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00534 | ||
| PWS Name: | MOLALLA, CITY OF | ||
| Who Was Contacted: | Seth Kelly | ||
| Contact Phone: | 503-302-3600 | ||
| Contact Date: | 02/19/2026 | ||
| Contacted By: | CALL, BAXTER (DWP) | ||
| Contact Method/Location: | Phone | ||
| Assistance Type: | MONITORING | ||
| Reasons: | Chlorine |
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| Details: | Operator contacted DWS to report that their finished water chlorine monitor (Hach CL17) was recording incorrect data compared to grab sample spot checks. DWS instructed operator that this constitutes failure of chlorine monitoring equipment, and the City should begin collecting grab sample readings every 4 hours until the on-line monitor was operational. The City conducted 4-hour grab sampling from 2/19 - 2/23 2026 and will retain the results for records. The City conducted extensive troubleshooting with operators and technical support from Hach. Equipment failure was ruled out after a different DPD regent Lot# was used for grab sampling. The issue was identified and replicated. Grab sample readings using reagent from one Lot# were consistently ~0.2 mg/L high. Switching to a different Lot# of reagent, grab samples have been in agreement with on-line measurements, indicating that the on-line instrument was reading correctly. |
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