Changes in Water Use & Wastewater Generation and Impact Fee Implications

Transcription

1 Changes in Water Use & Wastewater Generation and Impact Fee Implications What We Used To Think What We ve Seen What We ve Learned Where Are We Going? Why Is This Important? Immediate Practical Issues Big Picture Implications/Key Issues

2 What We Used To Think Demand from existing homes & businesses relatively stable New development flows would more than offset any reductions from existing base Focus on short-term, behavioral approaches to reductions Water demand & wastewater generation would grow steadily, even with rate increases

3 What We ve Seen Total water production remains stable even as growth occurs Volume to wastewater treatment plants stays about same Dry flows in sewers & lift stations in new areas very low Low flows lead to problems in water and wastewater systems

4 Total Water Production Remains Relatively Stable Even As Growth Occurs ( ) Account Growth and Total Water Consumption Number of Accounts (July) CONSUMPTION ACCOUNTS Total Metered Consumption (MG)

5 Phoenix Water Consumption: , , , , , , , , , Water Demand (AF) 1,000,000 1,100,000 1,200,000 1,300,000 1,400,000 1,500,000 1,600,000 1,700,000 Population Phoenix Per-Capita Use:

6 Total Flows to Wastewater Treatment Plants Remain Relatively Constant Even With Growth ( ) Average Daily Wastewater Generation (MGD) Fiscal Year

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10 What We ve Learned New development is more efficient than anticipated Major efficiency improvements in both indoor & outdoor water use Long-term structural shifts more important than short-term behavior Elasticity of demand complicated likely greater at higher rates

11 The More Recent The Construction, The More Efficient The Water Use Average Daily Water Use (2008) by Year of Home Construction 450 Average Gallons per Home Per Day (2008 Water Use) Year of Home Construction

12 Actual Flows For New Development Are Much Lower Than State or City Guidelines Indicate: Wastewater Example Land Use ADEQ Admin Code, Title 18, Ch. 9 Unit Avg Daily Flow/Unit (gal) City of Phoenix WSD Design Avg Daily Flow/Unit Unit (gal) City of Phoenix Wastewater Generation Unit Avg Daily Flow/Unit (gal) Single Family Residential dwelling 450 dwelling 320 dwelling 146 Multi-Family Residential 1 (Rental Apartments) dwelling 250 dwelling 250 dwelling 143 Commercial (Mall w/ Food Court) 1000 ft ft ft 2 77 Commercial (Big Box) 1000 ft ft ft Schools 2 (High School) student 28 student 75 student 21 1) ADEQ standard for multifamily is listed as 100 gallons per bedroom per day. The adjustment of 250 gallons per dw elling per day assumes an average of 2.5 bedrooms for multifamily. 2) ADEQ standards for schools distinguish daily flow rates for elementary students (23 gpd), middle/high school students (28 gpd), and staff (20 gpd).

13 Water Use Is Gradually Falling In Existing Homes and Businesses: Single Family Example Change in Water Use by Period of Home Construction Water Use Water Use 400 GALLONS/DAY Pre Post 1990 YEAR OF CONSTRUCTION

14 Behavior Remains Constant Improved Indoor Efficiency Is Largely Due to Fixtures & Appliances COMPARISON OF END-USE STATISTICS 1997 VS FIXTURE / CHANGE APPLIANCE GPHD GPHD GPHD Leak Toilet* Shower Faucet Clothes Washer* Other Bathtub Dish Washer Total

15 Outdoor Water Use Is Gradually Declining On A Per Unit Basis In New Development And Existing Areas Percentage of Homes with Turf Grass by Period of Construction 90.00% 80.00% 70.00% Percent of Homes 60.00% 50.00% 40.00% 30.00% 20.00% 10.00% 0.00% <= <=x<= <=x<= <=x<= <=x<= <=x<=2004 >=2005 Home Construction Cohort

16 Trend: Gradual Implementation of More Efficient Technologies in Households Preliminary Analyses PENETRATION RATE BY COHORT (280 Households) < >2004 All Percentage of Sample 13.31% 20.50% 12.23% 12.23% 13.67% 15.47% 12.59% % Low -Flow Toilets (1.6 gpf) 58.21% 67.89% 66.67% 64.94% 75.79% 97.39% % 77.78% Shower Heads (2.5 gpm) 80.30% 86.14% 71.64% 92.00% 74.16% 92.16% 96.47% 85.30% Bathroom Faucets (2.0gpm) 60.98% 60.34% 64.44% 80.19% 56.72% 68.86% 76.64% 67.19% HET Clothes Washers 13.79% 15.69% 12.90% 18.75% 38.89% 26.19% 39.39% 23.62% HET Dish Washers 9.52% 6.90% 8.70% 13.79% 19.44% 13.95% 34.29% 16.20% Irrigation Timer 24.32% 28.07% 41.18% 64.71% 78.95% 83.72% 91.43% 57.19% Pool 18.92% 19.30% 41.18% 52.94% 63.16% 44.19% 28.57% 37.05% Evap Cooler 27.03% 33.33% 35.29% 20.59% 5.26% 2.33% 2.86% 18.71% Turf 86.49% 77.19% 79.41% 73.53% 68.42% 48.84% 51.43% 69.42% Rock 21.62% 15.79% 26.47% 47.06% 57.89% 86.05% 71.43% 45.32% Cactus 29.73% 14.04% 41.18% 20.59% 34.21% 53.49% 37.14% 32.01%

17 Elasticity Of Demand Appears To Be Higher Than Anticipated In Phoenix and Elsewhere Utility State Historical Period Price Elasticity of Demand Factor Correlation of Price and Demand Data Las Vegas Valley Water District NV Strong Correlation City of Abilene TX Moderate Correlation Fort Wayne Water Utilities IN Moderate Correlation Boston Water & Sewer Commission MA Strong Correlation Greater Cincinnati Water Works OH Poor Correlation Louisville Water Company KY Very Poor Correlation City of Peoria AZ Poor Correlation City of Glendale AZ Strong Correlation Metropolitan Water District (Tucson) AZ Strong Correlation Phoenix Water AZ Strong Correlation

18 Where Are We Going? New development will continue to be more efficient than existing base Efficiency gains in existing base will likely continue for decades Networks will continue to expand but per unit flows will fall All other things being equal, rate revenue will fall unless rates are increased, and when rates are increased, demand will fall again

19 Why Is This Important? Design guidelines for new construction Infrastructure plans existing & new units future demand Water quality issues Water resource planning Long-term financial planning for growth Major implications for impact fee programs

20 Immediate Practical Issues Increasingly difficult to tie burden of new demand to water use proxies (meter size, fixture unit counts, etc.) Fire flow requirements, chlorine residual issues means lower volume not always leading to significantly less facility costs Falling demand affects treatment and network costs differently

21 Immediate Practical Issues Least beneficial effect of falling demand is on water network portion of water facility fees Some beneficial effect on water treatment and wastewater treatment/network costs Most beneficial effect of falling demand is on water resource fees Revisions to plans needed to take into account changes in per unit demand and facility requirements

22 Big Picture Implications/Key Issues If full cost fees not used larger burden placed on existing base if rates volume-based In Phoenix homes built in 70s, 80s use around 440 gpd; new homes use less than 300 Aside from equity issues reliance on rates now difficult because of decline in revenues With revenues falling around 1% year and heavy fixed costs no funding for growth

23 Big Picture Implications/Key Issues In period water, wastewater, water resource fees critical source of revenue City of Phoenix water-related fees produced almost $400 million in collections and probably $100 million in facilities Impact fee programs now under siege in Arizona 10 yr requirement will be difficult When growth comes back where does funding come from rates out, fees difficult?

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25 Big Picture Implications/Key Issues Implications of back-ending facility costs and then recouping through rates now apparent Some private utilities now raising rates 40, 50, 60% per year in Phoenix area By time public understands implications, often too late

26 Current Research Using existing historical water meter data in conjunction with other databases & GIS Collecting data on fixtures & appliances used by customers (site visits, sales, etc.) Using data loggers to track specific uses Using sub-meters to discern indoor/outdoor Doing sewer metering to track flows Modeling to bridge macro/micro divide

27 New Ways of Tracking Customer Use Data Logging Trace Analysis Discreet End-Use Information Example of trace analysis from City of Phoenix, Re-Log Study 2009

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