OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00585 | ||
| PWS Name: | OCEANSIDE WATER DISTRICT | ||
| Who Was Contacted: | Christian Anderson | ||
| Contact Phone: | (Email address hidden) | ||
| Contact Date: | 03/07/2025 | ||
| Contacted By: | ALFAFARA, NICOLE (DWP) | ||
| Contact Method/Location: | |||
| Assistance Type: | PRIORITY NON-COMPLIER | ||
| Compliance & Enforcement: | MCL Violation Notice: 05/24/2024 - 07/29/2024 | ||
| Details: | System has experienced elevated TTHM levels, resulting in multiple OEL reports and MCL exceedances in May, August, and December 2024. Mitigations efforts included: 1. Distribution System Adjustments: Flushing & Tank Draining: The 300,000-gallon Capes Reservoir was identified as a major contributor to elevated DBPs due to prolonged water age and low turnover. Partial draining in December 2024 slightly reduced TTHMs, with another drain scheduled for February 2025. Reservoir Level Adjustments: Setpoints were lowered to improve turnover and reduce stratification. Mixer Installation: A Tidal Wave Mixer is under consideration but faces challenges related to power supply, cost ($20-28K), and uncertain effectiveness. 2. Treatment & Coagulation Optimization: The system uses sodium carbonate and PASS-C coagulant, which has maintained UVA readings below 0.020 since April 2024. Alternative Coagulants suc has ACH or a mixed-media cartridge system may be explored but require engineering review and OHA approval. Potential Upgrades: OAWU and OHA suggested a settling clarifier and granular activated carbon (GAC) for DBP reduction. 3. Disinfection Adjustments: Chlorine Dose Reduction: Targeted clearwell residuals were set at 0.60-0.80 ppm, with adjustments made in January 2025. Target is to maintain a clearwell chlorine residual >0.6 mg/L. Erratic residual levels suggested potential dosing quill leaks. A new valve will be installed by March 2025 to stabilize dosing. Technician support is under consideration if issues persist. March 2025 Update: The second reservoir draining, combined with a lower chlorine dosage for disinfection and changing reservoir level setpoints to decrease contact time and increase turnover, led to a reduced TTHM level in the first-quarter 2025 DBP sample. System is optimistic that these practices, when consistently implemented, will help restore and maintain compliance moving forward. With the 1st quarter 2025 results the system is back in compliance. |
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| Associated Violations: | Viol #903129482, 10/01/2024 - 12/31/2024: DBP - Chemical MCL based on Locational Average of Samples Viol #903129480, 07/01/2024 - 09/30/2024: DBP - Chemical MCL based on Locational Average of Samples Viol #903129478, 04/01/2024 - 06/30/2024: DBP - Chemical MCL based on Locational Average of Samples |
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