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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 00359 | ||
| PWS Name: | CORBETT WATER DISTRICT | ||
| Who Was Contacted and Phone: | Jim Jans (503) 695-2284 | ||
| Contact Date: | 10/03/2013 | ||
| Contacted By: | NUSRALA, JAMES (REGION 1) | ||
| Contact Method/Location: | Office | ||
| Assistance Type: | OTHER REGULATORY - REGULATORY ASSISTANCE | ||
| Reasons: | SWTR Operations |
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| Details: | SUMMARY: CT determinations for September DETAILS: Jim contacted me on 10/1 to indicate Corbetts (CWD) 9/30 CT calcuation indicated that CTs were apparently not met due to low chlorine residual b/c of recent change to Accutab 70% calcium hypochlorite from sod. hypo. CWD had been calculating CTs by summing successive inactivation ratios for both cwell and reservoir to see if CTs are met as per OAR 333-061-0036 (5)(a)(D)(I)(II). After reviewing EPA guidance, 1991 SWTR Manual, systems with only one point of chlorine injection (like CWD) may calculate one inactivation ratio before or at first customer (after reservoir), as per 0036 (5)(a)(D)(I)(I). Successive inactivation ratio summing required for systems with multiple points of chlorine injection. On 10/3 I forwarded Jim updated CT worksheet with directions on completing it. CWD to calculate CTs for September ASAP to determine if CTs met each day with new worksheet and forward Sept Surface Water form to DWS for review. System to use new worksheet in future. See note to file. ACTION NEEDED: Corbett to recalculate CTs with approved formula (see note to file), which accounts for chlorine residual, pH, temp & flow after clearwell and reservoir, to determine if CTs met every day starting in September. DWS to review CT compliance and provide support to CWD as necessary. | ||