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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00799 | ||
| PWS Name: | SEASIDE WATER DEPARTMENT | ||
| Who Was Contacted and Phone: | Ben Davis (503) 738-5112 | ||
| Contact Date: | 12/02/2009 | ||
| Contacted By: | HOFELD, EVAN (REGION 1) | ||
| Contact Method/Location: | Office | ||
| Assistance Type: | OTHER REGULATORY - REGULATORY ASSISTANCE | ||
| Reasons: | SWTR None |
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| Details: | SUMMARY: CT and general compliance questions DETAILS: Ben left me a voice mail with several questions. I sent the following e-mail with responses: I originally had doubts about the baffling factor for the clearwell being as high as 97%, which is why I wanted to verify it with Rob Henry before answering your questions. He confirmed that the value is very high due to the clearwell baffling, narrow channels, and high turbulence through the clearwell at high flows. So to answer your questions: 1) Yes - you can use a contact time of 115 minutes for flows up to 2400 gpm. For flows in the range of 2400 - 2800 gpm, you can use the contact time of 94 minutes. 2) Attached is a spreadsheet for interpolating between required CT values in the CT tables. 3) You should contact the Drinking Water Program under the following circumstances: a) The entry point chlorine residual drops to less than 0.2 mg/l for more than 4 hours or exceeds 4 mg/l. b) CT is not met c) Turbidity exceeds 0.349 NTU in more than 5% of the readings (as submitted on the monthly turbidity reports) d) CFE turbidity exceeds 1.49 NTU e) IFE triggers are exceeded f) Chlorine residual in the distribution system is not detectable in more than 5% of the readings in a month or exceeds 4 mg/l g) Upon violation of any rules under OAR 333-061, maximum contaminant levels or for an event which you believe could put the public at risk from microbial or chemical contamination or following discovery of a deliberate act to sabotage treatment, tanks, pump stations, etc. Let me know if you have more questions. ACTION NEEDED: No further action needed at this time. | ||