7 City Council to Direct Staff to Approve the Installation of a VFD on Turbine #1 at the WWTP as Recommended by Staff.

Meeting Date: February 17, 2015

Note from TheGardeningSnail: Parts of this page may have been prepared by running a PDF Image Document through a program which converts image to text. My apologies for any Textual Gremlins that may have slipped in. Copy of the Original can be found on the City’s Website. I have also broken up some of the longer paragraphs for ease of reading and highlighted some of the more important details.

7. City Council to Direct Staff to Approve the Installation of a VFD on Turbine #1 at the WWTP as Recommended by Staff.

STAFF REPORT

AGENDA ITEM: City Council to Direct Staff to Approve the Installation of a VFD on Turbine #1 at the WWTP as Recommended by Staff.

MEETING DATE: February 17, 2015

PREPARED BY: Alfonso Manrique, Alternate City Engineer

REVIEWED BY: Odi Ortiz, Interim City Manager

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RECOMMENDATION:

City Council to Direct Staff to Approve the Installation of a VFD on Turbine #1 at the WWTP as recommended by Staff.

EXECUTIVE SUMMARY:

Since November 2014, the City has been implementing energy efficiency improvements at the WWTP. The energy efficiency improvements were recommended on an energy facility audit dated August 2014, prepared by Quest as part of the California Wastewater Process Optimization (CalPOP) Program.

The CalPOP program is a PG&E program intended to help municipal wastewater treatment facilities optimize their processes by reducing energy costs. The cost of the Facility Audit was to be fully covered by the CalPOP program.

The following are the August 2014 Energy Audit recommended energy efficiency measures:

• EEM # 1 -Replace existing DO sensor and optimize treatment process set points.

• EEM #2 – Install a second DO sensor and a VFD to control Turbine #2.

• EEM #3 – Install a MLSS sensor and a sludge thickener.

According to Quest’s Energy Audit, the implementation of the three EEMs would result in an estimated energy saving of approximately 481,000 kWh/yr or approximately $64,000/yr.

PG&E’s rebate for the implementation of the energy efficiency improvements was estimated to be $31,000. The estimated cost of implementation of the energy efficiency improvements was estimated to be approximately $380,000.

The payback on EEM # 1 and #2 was less than two years. The payback on EEM #3 was 110 years and did not make good financial sense from the energy savings standpoint. The implementation cost for EEM# l and EEM #2 was estimated to be $120,000.

BACKGROUND/DISCUSSION:

The City has completed the implementation of EEM #1. To date, the City has replaced the Dissolved Oxygen (DO) probe at the oxidation ditch and adjusted the dissolved oxygen concentration to reduce aeration requirement while maintaining adequate treatment. Power consumption has decreased significantly since the new DO probe was installed.

Figure 1 shows the decrease in consumption since December 15, 2014 when the DO sensor was commissioned. The reduction in power consumption is equivalent to a demand of approximately 62 kW. This reduction will result in an annual saving of approximately 543,000 kWh/yr or $70,200/yr. The savings realized to date exceed the estimated savings in the August 2014 Energy Audit.

The next energy efficiency improvement (EEM #2) consists of installing a second DO probe and a Variable Frequency Drive (VFD) on Turbine # 1. Turbine # 1 currently operates at constant speed. The VFD will be controlled by the new DO probe. Modifications to the PLC program will also be made to control the speed of Turbine # 1. Staff requested quotes from qualified electrical contractors to install a new VFD for Turbine #1. Four quotes have been received and are summarized in the following table:

Contractor

Quote

Western Water Constructors, Inc.

$49,000.00

Cooper Controls

$27,465.14

Telstar Instruments

$32,950.00

Tesco Controls, Inc.

$41,589.00

A new DO probe has been purchased and will be installed within the next three weeks. The cost of the DO probe was $6,112. The modifications to the PLC will be done by Tesco Controls, Inc. The estimated cost for the PL program modifications is $11, 140.00.

At this time, the implementation cost of EEM #1 and EEM #2 is expected to be less than the estimated $120,000 in the August 2014 Energy Audit.

FISCAL IMPACT:

Costs associated with the implementation of the EEMs are the responsibility of the City. Once the implementation is complete and the savings are verified by PG&E, a rebate will be issued to the City and all eligible costs will be reimbursed through PG&E’s On-Bill Financing (OBF) program.

The OBF program consists of a zero interest loan to pay for the implementation of qualified EEMs. Quest, as the CalPOP program administrator will process all the required documentation for the City.

ATTACHMENTS:

1. Figure 1

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2. Proposals from Western Water, Cooper Controls, Telstar Instruments, and Tesco Controls.

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