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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00970 | ||
| PWS Name: | NESKOWIN REG WATER DIST | ||
| Who Was Contacted: | Troy Trute | ||
| Contact Phone: | 503-392-3966 (Email address hidden) | ||
| Contact Date: | 11/24/2023 | ||
| Contacted By: | HOFELD, EVAN (DWP) | ||
| Contact Method/Location: | |||
| Assistance Type: | WATER QUALITY ALERT RESPONSE | ||
| Reasons: | Disinfection Byproducts |
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| Details: | On 11/22/23 I received an alert for a single TTHM result of 0.0983 mg/l from sampling completed 11/6/23 resulting in a locational running annual average (LRAA) of 0.043 mg/l and Operational Evaluation Level (OEL) of 0.062 mg/l for the 4th quarter of 2023. The system is already on standard quarterly monitoring and this did not result in an exceedance of the TTHM LRAA or TTHM OEL. I e-mailed Troy about the result on 11/24/23 and Troy called back on 11/29/23, sent me the results from the lab reports to verify the data, and discussed possible causes. The TOC results were unusually high at 3.45 mg/l (generally they are around 2 mg/l or less) and Troy mentioned that there was a higher chlorine demand earlier in the month. We concluded that the TOC levels spiked without a corresponding increase in coagulant, thereby resulting in the passage of soluble organics through the membrane filters to react with chlorine and form higher disinfection byproducts (DBPs). We discussed several ways of mitigating future events including more closely monitoring increases in chlorine dose and possibly monitoring UVT. I sent Troy a follow-up email on 11/30/23 with more info about UVT monitoring and let him know that no further action was needed at this time and to remain on quarterly DBP monitoring. | ||
| Associated Alerts: | DBP-50 - 11/22/2023 - TTHM |
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