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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 and Phone: | Guy Holzworth (503) 392-3966 | ||
| Contact Date: | 10/13/2007 | ||
| Contacted By: | POTTS, JOHN (DWP) | ||
| Contact Method/Location: | Field | ||
| Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
| Reasons: | N/A N/A |
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| Details: | SUMMARY: CT Tracer Study DETAILS: I reviewed 2003 tracer study to determine protocol to follow in order to reflect continuity in the study. I discussed the operational parameters with Guy prior to the study so the plant and storage systems would be operating to create worst case scenario in the system. The plant was set to operate at 300 gpm and verified. The valve to the storage tank (common inlet/outlet) was closed to force all the water into the main distribution system and first user at the old golf course clubhouse. The plant ran for 60 minutes prior to measurements. The chlorine residual at first use was a 0.2 mgl increase in residual at the first user for the t10 level. The clearwell contact time was 14 minutes as measured by chlorine residual in the lab sink. The base line residual was 0.7 and a residual of 0.9 mgl was measured at 14 minutes. At the first user measurement were taken at 2 minute intervals up to 43 minutes then at one minute intervals after that as the residual began to increase at that time. At 48 minutes the residual was 0.85 mgl, reflecting the target concentration (0.8 mgl) at first user. Chlorine readings were conducted every two minutes up to 64 minutes after increase in dosage with the residual increasing to 1.31 mgl at that time. Based on this study, the chlorine contact time at 300 gpm is 41 minutes. ACTION NEEDED: Prepare written report for the system and DWP | ||