|
|
| Introduction :: Data Search Options :: Water System Search :: DWS Home :: DWS Rules |
OHA Drinking Water Services
Contact Report Details |
|||
| PWS ID: | OR41 00466 | ||
| PWS Name: | LANGLOIS WATER DISTRICT | ||
| Who Was Contacted and Phone: | Dave Terrusa (541) 253-7556 | ||
| Contact Date: | 03/13/2007 | ||
| Contacted By: | STRASSNER, BOB (DWP) | ||
| Contact Method/Location: | Field | ||
| Assistance Type: | CIRCUIT RIDER ASSISTANCE | ||
| Reasons: | N/A N/A |
||
| Details: | SUMMARY: Turbidity Profiles DETAILS: The plant is treating raw water pumped from a screened intake in Flores Creek at a rate of 90 to 100 gpm. Raw water NTUs over this filter runs previously 16 hrs averaged 5.8 to 8. NTUs. Flores Creek can be quite flashy causing raw water turbidity events well above 200. Prior to backwash the preparation for the Turbidity Profile included a baseline of the settled water NTUs sampled from the top of the filter, at the location where the profile samples would be drawn. A siphon was started using a garden hose placing the intake just at the point on the surface of the filter where the backwash water would rise and spill into the wash water trough to waste during the backwash cycle. The continous flow was directed to the lab sink where the baseline settled NTU was measured at 0.859 NTUs. Sampling was begun at one minute intervals upon initiation of the backwash cycle. The dual media filter has 25 sq ft of surface area and typically filters water at 3.6 gpm sqft. Backwash is normally determined by the operator based on headloss. The plant does not have an auto shut down on high NTUs. Once backwash is initiated the operator using a large garden rake, lifts and separates in the anthracite layer until he feels free flotation of the media or visually sees the reddish tint of the garnet layer. The hydraulic flow through the filter is controlled through a water valve previously set by the operator at the lowers of 2 of the rates used during the process. Six minutes into the raking the operator resets the water valve to the higher rate and allows an additional 10 minutes of backwash. The pump times out after the cycle and the filter flows are reduced to a valve to allow restratification of the media layers to the operator opening a valve to allow the filter to reverse flow and begin a filter to waste cycle. ACTION NEEDED: Continue working towards a Tracer Study | ||