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OHA Drinking Water Services
Contact Report Details |
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| PWS ID: | OR41 05689 | ||
| PWS Name: | ROLLING ACRES WTR IMPROV DIST | ||
| Who Was Contacted: | Kelly Sevey | ||
| Contact Phone: | 541-698-6000 (Email address hidden) | ||
| Contact Date: | 07/26/2019 | ||
| Contacted By: | PARRY, BETSY (DWP) | ||
| Contact Method/Location: | Phone | ||
| Assistance Type: | WATER QUALITY ALERT RESPONSE | ||
| Reasons: | GWR |
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| Details: | Confirmation samples collected at their source (sounds like a dug well near a pond) confirmed the presence of fecal bacteria (E. coli) in the source water. The water system chlorinates, but to avoid a boil advisory, they must show that their disinfection treatment provides at least 4-log viral inactivation. Kelly Sevey is the new contact for the system. Over the phone, we reviewed the size and arrangement of their storage tank. He said they have 6 houses connected for a total of approx. 14 people, which helps to estimate the maximum demand flow on the system. The storage tank floor is some 22' below grade (they use a 24' extension ladder to access). Kelly also said the tank was square, some 10 or 12 foot across. (He was out of the area when I reached him so could not go look and confirm.) To be conservative, I used the smaller 10' x 10' x 22' tank size, totaling 2200 cu. ft., which is 16,457 gals. Then I ran a contact time estimate with the lowest operating level of 2/3 full, a baffling factor of 10%, and a maximum demand flow for 6 houses (with 5x peaking factor) of 8.33 gpm. Although the tank may be bigger than this in reality, even with this conservative estimate, they can meet the required CT disinfection level of 6 by maintaining a low chlorine residual of 0.045 mg/L at the entry point. Kelly has been keeping the level at 1.0 mg/L, and he checks it regularly. Given the data supporting this minimum level of disinfection treatment, they are not required to issue a boil advisory at this time. I will email Kelly the Monthly Monitoring Form for interim GWR 4-log treatment for the daily measurements. When he returns in a week, Kent Downs at Curry Community Health will follow the GWR procedure for confirmed EC+ at the source (a source evaluation request, etc.) to determine long-term options for the system. We also need to update the contact information in our database. |
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| Associated Alerts: | COLI19058 - 07/26/2019 - COLIFORM (TCR) COLI19042 - 07/19/2019 - COLIFORM (TCR) , E. COLI |
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