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In late 2001 and early 2002 the District performed a Particle Removal Demonstration Study. Based on the results, the Department of Health Services (DHS) determined that the existing inline, high-rate filtration process should be converted into a direct filtration facility through operational and mechanical improvements to the treatment process.

In August 2002, The District's consulting engineer, PACE Engineering, Inc., (PACE) completed a pre-design report recommending specific improvements to the District's Wintu Pump Station and Water Treatment Plant that would be needed in order to meet the requirements of the Department of Health Services (DHS). In December 2002 the District made application to the DHS for funding under the Safe Drinking Water State Revolving Loan Program. In September 2003 the District received notification from the DHS that its application had been approved and that the District would be eligible for a funding under the Safe Drinking Water State Revolving Fund.

In October of 2003 the District executed a contract with PACE for the preparation of construction plans and specifications for the project. The District staff worked closely with the engineers at PACE on the design of the improvements and the planning for construction that involved extensive modifications to existing facilities. The resulting design was completed in June 2004 and submitted to the DHS for their review and approval. After receiving approval from the DHS the project was put out to bid and bids were received on July 20, 2004.

The construction contract was awarded to Ray Toney and Associates on July 26, 2004, and the notice-to-proceed was issued on September 8, 2004. The contract for the supervisory control and data acquisition (SCADA) was awarded to Meyer Control Corporation.

It was anticipated that construction of the improvements would take approximately two years. In order to make the necessary modification to existing facilities at the Wintu Pump Station and the Water Treatment Plant while maintaining water service to its customers the contractor was limited to two shutdowns, each four months in duration, during the months of November to March. Construction began in September 2004 and was completed in July 2006. The total construction cost was approximately $7.8 million. Change orders on the project totaled approximately $0.4 million or approximately 5 percent of the original construction cost.

The updated facilities will provide substantial water quality benefits which include reduced filter loading rates, rinse to waste capability, independent monitoring and controls for each filter, improved coagulant and chlorine injection, and improved disinfection contact time. Additionally, the backup generator, variable speed pumps and extensive computer automation will provide improved reliability and service to its customers into the future.

Project Facts:

Wintu Pumping Plant:
  • Pumping Rates
  • Polymer Dosing Capability
  • Chlorine Scales
  • Chlorine Injection Point
  • Standby Generator
  • Valve Actuators
Before Construction
  • 15 to 45 mgd
  • none
  • mechanical
  • pump bays
  • none
  • hydraulic
Following Construction
  • 2 to 60 mgd
  • 2 @ 2.6 gallons/hour
  • digital
  • directly into the pipeline
  • 2.2 megawatts
  • electrical
Water Treatment Plant
  • Filters
  • Filter Area
  • Filter Capacity (w/ all fIlters)
  • Filter-to-waste
  • Filter Flow Meters
  • Treated water "CT" contact time
  • Total "CT" contact time
Before Construction
  • 10
  • 5,000 square feet
  • 43.2mgd
  • none
  • none
  • < 1 min. @ 52.5 mgd
  • 24 min. @ 52.5 mgd
Following Construction
  • 16
  • 8,000 square feet
  • 69.1 mgd
  • on all 16 fIlters
  • on all 16 filters
  • 20 min. at 52.5 mgd
  • 44 min. @ 52.5 mgd
Quail Ridge Pump Station
  • Pumps
  • Variable Speed Drives
  • Pumping Capacity
  • PLC/SCADA Controls
Before Construction
  • 2@20hp
  • none
  • 900 gpm
  • no
Following Construction
  • 2 @ 50 hp & 1 @ 10 hp
  • on all 3 pumps
  • 3,000 gpm
  • yes

Project Benefits

  • The addition of coagulant at the Wintu Pump Station satisfies the DHS requirements for "direct filtration".
  • 600 hp variable speed pumps allows the District to pump continuously during low flow periods and avoids surging (starting and stopping) the flow through the Water Treatment Plant that was required when using the 15 mgd constant speed pumps. These pumps also lessen the impact on the filters as flows are increased and decreased gradually throughout the day to match customers demands.
  • Emergency generator at Wintu Pumping Plant capable of running two 1000 hp pumps and one 600 hp pump simultaneously thereby enabling the District to continuously pump and treat water during an electrical power supply failure.
  • The additional filters enable the District to meet the DHS maximum surface loading rate of 6 gpm/sq. ft and increase the maximum capacity of the Water Treatment Plant from 43 to 69 mgd.
  • The "CT" pipeline provides additional disinfectant contact time allowing the District to reduce the amount of chlorine it uses for disinfection and reduce the concentration of chlorine in the water leaving the Water Treatment Plant.
  • The new variable speed pumps at the Quail Ridge Pump Station enable the District to maintain a constant pressure within this zone and enables the District to meet fire flow demands.
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