OHA Drinking Water Services
Contact Report Details

PWS ID: OR41 00063
Who Was Contacted and Phone: Signe Hamlin (503) 458-6555
Contact Date: 11/06/2008
Contacted By: HOFELD, EVAN (REGION 1)
Contact Method/Location: Office
Reasons: Operations
Details: SUMMARY: Low Pressure and High Chlorine Residual Event DETAILS: Signe Hamlin called to report that due to a malfunction with the chlorinator at the slow sand plant, chlorine residuals spiked to 6.9 mg/l at the effluent of the slow sand reservoir. While the slow sand plant was off-line to repair the chlorinator and the rapid sand plant off-line for routine maintenance, water levels in the reservoirs dropped causing a drop in pressure in the distribution system. Signe assured me that neither reservoir went completely empty, so pressure in the distibution system was not totally lost. Since a violation of the chlorine maximum residual disinfectant level (MRDL) of 4.0 mg/l is based upon a running annual average of chlorine results, a temporary spike in chlorine levels in one part of the distribution system does not require public notification. As long as the pressure in the distribution system did not drop to zero psi, a boil water notice would not be required. Information was sent to Signe just in case a 24-hr boil water notice due to zero pressure or an MRDL violation requiring a 30-day notice did occur. I advised that they monitor chlorine residuals, take additional coliform samples, and keep our office apprised of any adverse results. I also advised Signe to include information in the next mailing to customers to explain the events leading to changes in system pressure and elevated chlorine residuals. ACTION NEEDED: Monitor system pressure and chlorine residuals, improve chlorinator malfunction safeguards, and issue public notice if a violation of the chlorine MRDL or a total loss of system pressure is experienced.

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System Info :: Report for Lenders :: Alerts :: Violations :: Compliance & Enforcement :: Contacts & Advisories :: Site Visits :: Public Notice
Coliform Summary :: Coliform Results :: Sampling Schedule for Coliform :: Groundwater/GWUDI Source Details :: Plan Review
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Lead & Copper :: Corrosion Control (LCR) :: Nitrate :: Arsenic :: Radionuclides :: GWR 4-Log :: LT2 :: Cyanotoxins
DBPs :: TOC & Alkalinity :: DBP Sample Sites :: FANLs :: MRDL :: Turbidity :: SWTR :: RAA :: LRAA For SDWIS: 3875