Assessment_Real_Water_Loss_Standard_and_Customer_Meter_Inacuracy_PL11032023.pdf

CITY OF PALO ALTO

UTILITIES DEPARTMENT

WATER, GAS, WASTEWATER ENGINEERING

WATER ENGINEERING GROUP

Presented by: Patrick LaBruzzo, P.E.

November 6, 2023

Customer Meter Inaccuracies Data and

2028 Real Water Loss Target

Discussion

UTILITIES

City of Palo Alto, Utilities Department

Water, Gas, Wastewater Engineer: Water Engineering Group

Presenter: Patrick LaBruzzo

UTILITIESINTRODUCTION

• Real Water Loss Standards, Calculations, and Modeling adopted in October 2022 (as Mandated by SB 555)

• No deadline for submitting adjustments to Real Water Loss Standard

• Compliance required by 2028

• MINIMUM REGULATORY GOAL for a real water loss of 16 GPCD

• In 2020 Revised Audit forms were submitted and it changed the City’s real water losses and standards:

• Revised Real Loss became: 25.3 GPCD with a 17.2 GPCD standard.

• Prior to 2020 audit revisions the real water losses would have been:

• Real Water Loss for the City of Palo Alto would have been 15.2 GPCD with a standard of 15.2 GPCD

• In 2023 adjusted parameters were submitted and it changed the City’s real water losses and standards to:

• Revised Real Loss became: 25.3 GPCD with a 24.6 GPCD standards.

Presenter: Patrick LaBruzzo

UTILITIESINTRODUCTION

• COMPARISON OF CITY OF PALO ALTO WITH OTHER CALIFORNIA AGENCIES:

Average Real Water Loss of BAWSCA Agencies is

18.75 GPCD, with a majority of agencies reporting between 6 and 30 GPCD.

State-wide Average Real Water Loss Baseline for all 456 reported systems is

34.3 GPCD, with a majority of agencies reporting between 4 and 65 GPCD

State-wide Average Real Water Loss Standard is

20.1 GPCD

• City of Palo Alto will have a greater leakage rate than the majority of systems by 2028 if all water systems comply.

Presenter: Patrick LaBruzzo

UTILITIESNEW REPORTING

• The SWRCB- Water Loss Control Group constructed models and based real water loss standards on established industry practices for reducing real water loss with leak detection.

• There are 27 modeling parameters needed to make the model accurate.

• The Water Boards rulemaking Effectively requires agencies to validate and revise data to ensure the model accuracy of the parameters.

In 2023, the parameter changes effectively removed real water loss reduction requirements, however the real water loss standard of 24.5 gpcd must be maintained from 2028 through 2051.

Presenter: Patrick LaBruzzo

UTILITIESNEW REPORTING

• GUIDANCE FOR CONSTRUCTION METER INACCURACIES (CMI)

• Requires 1% inaccuracy for all customer delivery volumes, this number is very low

• Requires the supplier to submit a statistical analysis to support alternative inaccuracies

• PAST CMI ESTIMATE for 2019

• Between 50-100 meters tested a year

• Calculated means and standard deviations

• Additional analysis needed to adjust CMI

• REGULATORY GUIDANCE FROM AWWA used by the State requests a STATISTICALLY SIGNIFICANT data set

• VALIDATORS requested a CMI with a 95% confidence level

Presenter: Patrick LaBruzzo

2019 CMI ESTIMATE

Analysis of Water Meter Testing Data Results 1985-87 1988-1990 1991-93 1994-2004 Quadrant 1 Quadrant 2 Quadrant 3 Quadrant 4 All Meters

Number of Meters 23 58 13 8 23 28 26 24 101

Average Age (Years) 31.7 30.7 27.0 21.2 31.7 30.4 30.5 26.5 29.8

Average Accuracy, All Data Set (%) 96.7 94.3 98.3 97.4 96.7 96.2 92.4 97.0 95.6

Standard Deviation of Accuracy (%) 8.4 13.7 6.0 2.8 8.4 5.0 19.8 5.2 11.4

Average Accuracy Excluding 0's (%)* 98.1 96.0 98.3 97.4 98.1 96.2 96.1 97.0 96.8

Standard Deviation Excluding 0's (%) 8.4 5.4 6.0 2.8 8.4 5.0 6.1 5.2 5.2

Average Min. Accuracy, All Data Set 91.5 90.3 94.1 94.8 91.5 93.0 88.0 92.9 91.3

Average Min. Accuracy, Excluding 0's 95.6 91.9 94.1 94.8 95.6 93.0 91.5 92.9 93.2

Averages for Each of the Accuracy Measurements (Including zeros)

Accuracy( '1/4 Gallon Per Minute and 1 Cubic Feet) 91.8 90.9 94.8 96.1 92.2 93.8 88.4 93.8 92.0

Accuracy (2 Gallon Per Minute and 1 Cubic Feet) 98.9 96.3 100.0 97.9 99.0 97.6 95.0 98.6 97.5

Accuracy (10 Gallons Per Minute and 10 Cubic Feet) 98.8 95.7 100.0 98.1 98.9 97.4 93.9 98.7 97.1

Averages for Each of the Accuracy Measurements (Excluding zeros)

Accuracy( '1/4 Gallon Per Minute and 1 Cubic Feet) 96.2 92.5 94.8 96.1 96.4 93.8 92.0 93.8 94.3

Accuracy (2 Gallon Per Minute and 1 Cubic Feet) 98.9 98.0 100.0 97.9 99.0 97.6 98.8 98.6 98.5

Accuracy (10 Gallons Per Minute and 10 Cubic Feet) 98.8 97.4 100.0 98.1 98.9 97.4 97.7 98.7 98.1

Presenter: Patrick LaBruzzo

UTILITIESNEW REPORTING

• CURRENT CMI ESTIMATES for 2022

• 287 meters tested

• Calculated p-test CMI with a 95% confidence level

• Mean is 90% accuracy for small meters, but a null hypothesis of at least 93% needed to reject random population and prove statistical significance for the sample set of 287 meters.

• LARGE AND SMALL METER TESTING

• A significant volume of small meter testing has been completed and will need to continue every year.

• 2023 will be the first year of large meter sampling. With the 6 meters completed, should be statistically significant for +7% at a 95% confidence level. For example if the mean is 80%, a value of 87% accuracy could be used.

• CURRENT REAL WATER LOSS FOR THE 2022 WATER AUDIT

• With 1% CMI, Real Water Loss is 630.303 acre-ft/yr & 23 GPCD

• With 3.78% CMI, Real Water Loss is 341.799 acre-ft/yr & 12.5 GPCD

Presenter: Patrick LaBruzzo

UTILITIESNEW REPORTING

• 3RD PARTY REVIEW AND VALIDATION OF AUDIT

• Audit will be completed and submitted to the validator this Friday

• Pending weighted retail unit cost calculation from the business group

• Submitting SFPUC meter data for production water volumes

• Preliminary review and conference call with validator will be November 22nd

• Final validation and submission by January 1, 2024

• PENDING STATE RESPONSES TO CPA STANDARDS

• The State’s regulatory published standards released for the City of Palo Alto is 17.1 GPCD

• State representatives and CPAU have been corresponding and clarifying the Real Water Loss Standard

• The State’s published standard on August 22, 2023; doesn’t reflect the submitted

Presenter: Patrick LaBruzzo

UTILITIESPROPOSED REPORTING

• Keep Baseline Real Water Loss of 24.6 and Improve Real Water Loss Accounting into the Future

• 2024 Audit and into the future

• Will include large meter accuracies, and more accurate CMI’s will be submitted beginning in 2023

• May include Supplier provided estimates for:

• Unbilled Unmetered, Authorized Consumption – Need fire departments estimates

• Systematic Data Handling Errors – Detailed assessment of handling unread meters and billing practices

• Unauthorized Consumption – Conduct an investigation to estimate unauthorized consumption

UTILITIESPROPOSED REPORTING

Potential Rough Comparison of the 2022 Water Audit Break-down of losses with a Rough

Guestimated Water Loss Break-down, if all water loss accounting practices are implemented by 2024.

2022 Water Audit Breakdown of

Real Water Losses

Guestimation of a

Potential Breakdown of Real Water Losses by 2024, if All

Practices

Implemented

Real Water Loss 43%

Unbilled Unmetered 3%

Systematic Data Handling Errors 3%

Customer Metering Inaccuracies

48%

Unauthorized Consumption 3%

Real Water Loss 29%

Unbilled Unmetered 2%

Systematic Data Handling Errors…

Customer Metering Inaccuracies

67%

Unauthorized Consumption 1%

Presenter: Patrick LaBruzzo

UTILITIESPROPOSED REPORTING

• Implement improved economic loss modeling and leakage surveying data by 2025

• Update Reported Water Loss information – includes response times, number of breaks, and estimated volumes

• Update leakage repair and spot repair cost information

• Estimate unreported water loss volumes from small leakage survey that is proposed in 2024

• Update ICF & ILI values to calculate a more accurate volume estimate of background water loss.

• By the end of 2026, finalize procedures for calculating losses

1. Real Water Loss and

2. Percentages for Reported Water loss, Unreported Water Loss, and Background Losses

• By the end of 2027, finalize a plan for compliance with the 2028 Water loss Target (It may be “DO NOTHING”).

Presenter: Patrick LaBruzzo

UTILITIESCONCLUSION

Questions and Answers

UTILITIES