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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00172 | ||
| PWS Name: | CASCADE LOCKS, CITY OF | ||
| Who Was Contacted: | Sheldon Price | ||
| Contact Phone: | 541-374-8484 | ||
| Contact Date: | 04/04/2022 | ||
| Contacted By: | CIVIL WEST ENGINEERS, INC (DWP) | ||
| Contact Method/Location: | Phone | ||
| Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
| Details: | Background/Problem Identification: Evan Hofeld of OHA requested circuit rider assistance regarding troubleshooting the corrosion control system at Cascade Locks. Assistance Provided: Civil West spoke with Sheldon Price at length about the corrosion control issues they have been having at Cascade Locks. The system was designed to dose based on pH, and the pH probe was located not far downstream from the soda ash injection location. This was causing the dosing system to read pH much higher than the actual pH, and consequently, the system was not dosing enough soda ash. Sheldon was able to modify the system to dose based on flow pacing the soda ash dosing pump with the WTP effluent, and this has allowed the system to dose more accurately. After making this change, Sheldon noted that they are still having issues with keeping the alkalinity above 30 mg/L, as required by OHA. Civil West requested WQP data from Sheldon and a scanned sheet from the Oct. 2016 corrosion control report was provided and reviewed. Based on the data from this sheet, the recommend treatment per the EPA OCCT (Flowchart 1a) included adjustment of pH with soda ash. Flowchart 1a also included caustic soda, which is known to have a greater effect on alkalinity than soda ash per raise in pH. Our recommendation to the City of Cascade Locks is to firstly increase their soda ash dosage to keep the pH and alkalinity above both OHA required levels of 7.0 and 30 mg/L, respectively. If increasing the soda ash dosage does not both keep the copper level down and raise the pH and alkalinity above the required levels, we recommend trying caustic soda instead of soda ash. Follow-Up Actions Needed: The circuit rider is able to assist further as needed. Technical Reports to be Prepared and Expected Timeframe: N/A. |
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