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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00954 | ||
| PWS Name: | WILSONVILLE, CITY OF | ||
| Who Was Contacted: | Delora Kerber | ||
| Contact Phone: | 503-570-1542 | ||
| Contact Date: | 02/28/2019 | ||
| Contacted By: | SALIS, KARI (DWP) | ||
| Contact Method/Location: | Field | ||
| Assistance Type: | OTHER WATER QUALITY - meeting to discuss pre-filtration ozonation credit | ||
| Reasons: | SWTR |
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| Details: | Pete Farrelly and I met with Delora Kerber and Patty Nelson from Wilsonville, Kim Reid and Howard Hamilton from Veolia, Jude Grounds and Meghan Schell from Carollo, to discuss their waiver application to award giardia inactivation credit for pre-filtration ozonation and some questions we had. We discussed the tracer studies and how ozone CTs are calculated, the City's plan to conduct a new ozone tracer study to reflect how they intend to calculate CTs, capacity of the ozonators during adverse water quality, alarm settings on post-sedimentation turbidity and response, what happens during a power outage, possible future reporting of ozone CT calculations, and bird deterrents to minimize risk of recontamination. Next steps: the City will amend their waiver application to focus on pathogen removal and inactivation through the treatment train to inform the decision of providing equivalent public health protection. This will include CTs achieved with chlorine after filtration and documenting how the above issues are handled. The City will further investigate a 2014 event to assure settled water turbidity alarms operated as designed. If not, the City will determine when were the alarms were set. The City has informed us that they plan to request an increase in the filtration loading rate soon. we advised them to request that soon rather than after OHA responds to this waiver request, as the filter loading rate could be related. |
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