OHA Drinking Water Services
Contact Report Details |
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PWS ID: | OR41 00548 | ||
PWS Name: | CLARKS BRANCH WATER ASSOC | ||
Who Was Contacted and Phone: | Mary Gouin (541) 863-7221 | ||
Contact Date: | 07/09/2013 | ||
Contacted By: | CREMENT, BRADLEY (DWP) | ||
Contact Method/Location: | Field | ||
Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
Reasons: | N/A N/A |
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Details: | SUMMARY: Enhance Contact Time DETAILS: CBWA owns & operates a community WS serving 140 people through 80 connections. Water is supplied by the South Fork of the Umpqua River where it is pumped to an ECI package plant. Treatment includes flocculation, sedimentation, single mixed media filter, disinfection & a 3,000 gallon clearwell. In addition to the clearwell, there are four (4) horizontal steel storage tanks located outside the treatment plant that provide storage & additional contact time. A previous contact study was performed (in 2006) by the circuit rider who found a contact time of 36-minutes at the peak production rate of 60 gpm. Given this was significantly lower than the 200-minutes of contact time that was historically used-- CBWA again contacted the circuit rider to request another tracer study. Met with operators on-site to evaluate their tank configuration. They have 4 horizontal steel storage tanks that are currently connected in parallel. This configuration creates a hydraulic short circuit during normal operation deeming most of the storage useless for contact time. The configuration also creates stagnant segments in two of the tanks. Discusses with the operators the need to reconfigure the tanks to maximize contact time & to eliminate the stagnant segments in their storage tanks. This can be achieved by switching the tanks from a parallel configuration to configuring them in series. Finalized report & provided conceptual drawing showing piping changes needed to reconfigure the tank flow. ACTION NEEDED: As requested by the Association. |