OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details

PWS ID: OR41 00554
Who Was Contacted: Brian Moore
Contact Phone: 503-368-5155 (Email address hidden)
Contact Date: 11/16/2021
Contacted By: HOFELD, EVAN (DWP)
Contact Method/Location: Phone
Reasons: Disinfection Byproducts
Details: I received an alert on 8/25/21 for elevated DBP levels of 0.0835 mg/l for TTHM and 0.0719 mg/l for HAA5. These results did not cause an exceedance of either MCL based on a locational running annual average (LRAA) calculated each quarter or the Operational Evaluation Level (OEL), therefore no further action was required. I spoke to Brian about these results as part of a subsequent OEL exceedance for HAA5 due to elevated results in sampling completed 11/4/2021 (see separate contact report dated 11/16/21) and he was aware of the elevated levels in August, however I could not remember if I had reached out and left a message to the previous operator, Don Davidson, at that time or not as there were operations personnel changes occurring at that time. I do recall speaking about the results with Dan Vaage, who had assisted with an OEL exceedance in 2020 and had been working with the City on conducting a tracer study and improvements to chlorine monitoring. I recommended Brian reach out to Dan Vaage with Civil West under the SRF Circuit Rider assistance program and he said he would. I also spoke about improved flushing and more monitoring of chlorine residuals in the distribution system, which range from about 0.3 - 0.6 with a low of about 0.2 mg/l at the DBP sample site, to find areas of low chlorine residual and potential areas to flush more. The high DBP results generally appear to occur in the fall, however, high results were seen in May 2020. With cartridge filtration, treatment options for TOC removal are limited.
Associated Alerts: CHEM9434 - 08/25/2021 - TOTAL HALOACETIC ACIDS (HAA5) , TTHM

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DBPs :: TOC & Alkalinity :: DBP Sample Sites :: FANLs :: MRDL :: Turbidity :: SWTR :: RAA :: LRAA For SDWIS: 3975