OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details
PWS ID: OR41 00585
PWS Name: OCEANSIDE WATER DISTRICT
 
Who Was Contacted: David Norman
Contact Phone: (Email address hidden)
Contact Date: 05/21/2024
Contacted By: ALFAFARA, NICOLE (DWP)
Contact Method/Location: Email
 
Assistance Type: WATER QUALITY ALERT RESPONSE
Reasons: Disinfection Byproducts
 
Details: In May of 2024 the systems DBP quarterly sample taken on May 7th resulted in the system TTHM exceeding both the OEL and the LRAA MCL of 0.08 mg/L (TTHM LRAA = 0.089 mg/L and TTHM OEL = 0.085 mg/L).
The system was encouraged to reach out to the Circuit Rider to address the ongoing DBP level and was notified of the need to take the following steps:
-Email DWS with a written plan within 90 days outlining how they will lower TTHM levels below the MCL that includes a projected timeline.
-Issue a public notice (PN Template) within 30 days to customer and submit a copy to DWS.

Prior DBP Issues:
In May 2022, a high TTHM result was noted, but calculations showed no exceedance of the OEL or LRAA MCL so no further action was needed. In August 2023, another high TTHM resulted in the system surpassing the OEL (no LRAA MCL exceedance), triggering an OEL report. This recurrence prompted a recommendation to monitor and adjust coagulant treatment methods. The system speculated an algal bloom in the water source, combined with telemetry problems causing reservoir sediment disturbance, might be the root cause. Additionally, they mentioned exploring the use of a more potent muriatic acid for membrane cleaning. In November 2023, another TTHM result exceeded the OEL (no LRAA MCL exceedance) triggering the need for another OEL report. Issues with soluble organics, improper coagulant (PASS-C) dosage, and tank cleaning were identified. Plans were made to address these concerns through tank cleaning and adjusting coagulant dosage to reduce soluble organics.

-7/3/24 Update: DWS Staff emailed system inquiring if they had a copy of the required PN (due 6/23/24) or needed assistance with the PN.
-7/9/24 Update: DWS Staff received PN on 6/18/24. DWS staff reminded system a plan to lower TTHm levels is due 08/22/24.
 
Associated Alerts: DBP-76 - 05/15/2024 - TTHM


More information for this water system: SDWIS ID 3980
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