OHA Drinking Water Services
Contact Report Details |
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PWS ID: | OR41 00581 | ||
PWS Name: | OAKLAND, CITY OF | ||
Who Was Contacted and Phone: | Dan Kelly (541) 459-4531 | ||
Contact Date: | 01/18/2008 | ||
Contacted By: | BYNUM, ROBERT (DWP) | ||
Contact Method/Location: | Field | ||
Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
Reasons: | N/A N/A |
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Details: | SUMMARY: Intake and WTP Sand clogging DETAILS: System has struggled with sand and sediment issues since the plant started up several years ago. Source is Calapooya Creek which has heavy sediment loads and high turbidity. Sediment problems may have increased with removal of an upstream dam which may continue to impact the plant for many years. Turbidity values over 1000 NTU have been recorded. First intake constructed with the plant did not work during winter periods and a second infiltration gallery intake was then constructed. The sand has damaged pumping, rapid mix equipment, hydraulic valves and clogged pH sensors and raw water turbidity equipment. The City requests assistance to troubleshoot the issue to determine if solutions exist. I visited the plant and inspected equipment layout and damaged parts. I reviewed plans available on the infiltration gallery and discussed past problems, current problems and potential remedies with operator and council members. First intake was constructed in a channel below normal stream bottom resulting in continuous sand problems. Air burst compressor appears to be too small taking at least 25 minutes to recharge to air tank. Even with adequate air bursts, expelling sand from around the screen will likely not be possible. Second intake reportedly provides adequate winter flows only because it was tied to an older abandoned surface water intake exposed in the stream bottom indicating sail permeability insufficient for the infiltration gallery to work. This results in sand and sediment intrusion into the screen interior-- however some settling is occurring in the wet well and adequate winter flows are being obtained. City believes that the settling pond may be a solution. ACTION NEEDED: Asked to investigate options and provide potential solution costs. Ideas include a sand separator, storage/settling pond, and a new intake deeper location. |