OHA Drinking Water Services
OHA Drinking Water Services
Contact Report Details
PWS ID: OR41 00236
PWS Name: COTTAGE GROVE, CITY OF
 
Who Was Contacted and Phone: Ray Pardee (541) 942-7064
Contact Date: 10/28/2010
Contacted By: LYON, CASEY (REGION 2)
Contact Method/Location: Office
 
Assistance Type: OTHER REGULATORY - REGULATORY ASSISTANCE
Reasons: SWTR
None
 
Details: SUMMARY: high turbidity event DETAILS: Ray Pardee called to inform me of a high turbidity event that occurred on 10/28/10 from midnite to 5 am at their layng creek WTP, EP-A. The CFE turbidity at 12 midnite was 0.41 and spiked as high as 1.56 but then came back down to 1.06 at 4:00 am. The high turbidity event was due to a combination of things-- a large storm produced raw water above 10 NTU as well as the operators had been changing the flow rate down on the two old filters at Layng creek WTP. Flow adjustments were made just prior to the high turbidity event and a possible over-dosing of alum also was a factor. The operators were able to bring the turbidity down to 0.28 NTU at 5:30 am with use of a filter aid and jar testing to find the proper alum dose. The major change that occurred as a result of this event was the city of Cottage Grove shut off the main line valve that fed this water produced from Layng creek WTP to the city, thus officially seperating the two systems indpendant from another. The Layng creek WTP is now operated by Row River Valley W.D. 01515 and is in transition to membrane filters, very soon RRVWD will abandoned the old filters completely. Since no MCL violation occurred and no treatment technique violation occurred, no public notice was required. IFE triggers did exceed, however since the operators were able to bring the filters back fairly quickly and this was a relatively short event,a written summary located in the RRVWD file will suffice in leui of the normal follow up actions required when IFE triggers are exceeded. RRVWD expect to be using the membrane plant 100% in the very near future, pending fixing some distribution leaks. The city of Cottage Grove now is using the Row river membrane plant for 100% of its water. ACTION NEEDED: no further action.

More information for this water system: SDWIS ID 4293
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