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UNIT FACTOR RATE ASSIGNMENT STUDY, PHASE I-II
MWEA Annual Conference June 20, 2016
BACKGROUND
Oakland County Schedule of Unit Assignment Factors Table
Utilized by the Oakland County Water Resources Commission (WRC) and many communities for determination of water & sewer use factors for different development types
Uses a Single Family Residential property as the baseline for all comparisons by assigning a unit factor of 1.0 to this use
Describes many different development types & assigns a Residential Unit Equivalent (REU) factor relative to a Single Family Residential use
PURPOSE
The current Schedule has not been updated since 1998
Disputes have been filed with the County over sewer connection fees & rates
Residential water usage is declining
High-efficiency appliances & fixtures are becoming increasingly popular
55 Non-Residential Categories Total
PURPOSE
Phase I :
Updating & Quantifying the current Residential Equivalent Unit (REU)
- Analyze residential billing data for actual metered water usage
- Analyze SEMCOG demographic and industry water/wastewater usage guidelines
Phase II:
Updating the 1998 Schedule of Unit Assignment Factors Table
PHASE I BACKGROUND
Current Assumed Usage of a Single Family Residential Sewer Customer:
90 Gallons/Person x 3.5 People = 315 Gallons/1 Day 1 Day 1 Single Family Household 1 Single Family Household
315 Gallons x 365 Days = 114,975 Gallons = 15,370 ft3 1 Day 1 Year 1 Year 1 Year ACTUAL Demographics for Oakland County: People per Household (2010) – 2.49 People per Household (2013) – 2.44
INDUSTRY WATER GUIDELINES
Source: Phase I Standardized Water Usage
(gallons/person/day)
Oakland County (WRC) 113
GLUMRB 125
Haestad Methods 93
Innovyze 94
USGS (Michigan Average) 80
USGS (U.S. Average) 98
Aquacraft, Inc. 69
GLUMRB = Great Lakes Upper Mississippi River Board
Haestad Methods = Corporation specializing in Water Distribution Modeling / Wastewater Collection Modeling & Design
Innovyze = Corporation specializing in Water/Wastewater Utilities Modeling and Planning
Aquacraft = Corporation specializing in Water Use Studies & Water Conservation Programs
PHASE I METHODOLOGY
11 WRC Billing Communities Were Surveyed:
Bingham Farms
Bloomfield Hills
Commerce Township
Farmington Hills
Highland Township
Keego Harbor
Lyon Township
Oakland Township
Orchard Lake
Oxford Township
Royal Oak Township
PHASE I METHODOLOGY
Actual WRC community quarterly meter billing data was collected and analyzed from 2010-2013
Only meter readings from November – April (non-irrigation usage) were obtained
Usage data from 5/8-inch & 1-inch residential water meters were analyzed
Groupings of 5 and 10 unit (1 unit = 100 CF) usage intervals for residential 5/8” and 1” meters were developed and plotted against the number of account readings within each interval over the 4 year study period
The data was analyzed at 90% / 95% / 100% of community billing accounts where 90% excluded the high and low 10% of accounts and 100% excluded 0% of accounts to illustrate impact on water usage by high and low end accounts in the analysis
Water usage was analyzed, comparing 80% / 90% / 95% of water usage being returned to the system as wastewater
Sewer lead infiltration rates were also analyzed at (5% / 10% / 15%) of water used
Actual billed usage averages for each community were calculated along with a weighted overall usage for all 11 communities
DEMOGRAPHIC ANALYSIS
Data analyzed:
Population
Occupied Units
People per Household
Median Housing Value
Median Household Income
Average Water Usage (Units)
As these values increase, so does water usage
COMMUNITY Consumption/ Household (gpd)
Avg. Household Value
BINGHAM FARMS 187.2 $391,900
BLOOMFIELD HILLS 203.6 $715,300
COMMERCE TOWNSHIP 153.7 $229,300
FARMINGTON HILLS 166.0 $238,300
HIGHLAND TOWNSHIP 201.1 $212,900
KEEGO HARBOR 134.6 $156,900
LYON TOWNSHIP 180.4 $242,400
OAKLAND TOWNSHIP 241.4 $342,000
ORCHARD LAKE 189.3 $588,200
OXFORD TOWNSHIP 171.4 $342,000
ROYAL OAK TOWNSHIP
143.0 $99,800
OAKLAND COUNTY 179.3
WATER USE VS. PEOPLE PER HOUSEHOLD
WATER USE VS. WATER RATES
EXAMPLE COMMUNITY WATER USAGE CALCULATION
COMMERCE TOWNSHIP
COMMERCE TOWNSHIP SEMCOG POPULATION DATA
Demographics 2010 2013 Change (2010-
2013)
Population 35,874 36,570 1.9%
Occupied Units 13,220 13,674 3.4%
People per Household 2.71 2.67 -1.5%
Median Housing Value $229,300 N/A N/A
Median Household Income $82,691 N/A N/A
COMMERCE TOWNSHIP DISTRIBUTION OF WATER CONSUMPTION
1” & 5/8” Meter Data Averaged from 2010-2013 Winter Quarters
COMMERCE TOWNSHIP WATER USAGE WITH 10% OF HIGH AND LOW END ACCOUNTS EXCLUDED
Middle of 90% of 1” & 5/8” Meter Data Averaged from 2010-2013 Winter Quarters
COMMERCE TOWNSHIP WATER USAGE WITH 5% OF HIGH AND LOW END ACCOUNTS EXCLUDED
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Units Used (1 unit = 100 CF water)
Commerce Township: Distribution of Water Consumption
COMMERCE TOWNSHIP ANALYSIS SUMMARY
Calculated water use for 1 REU in Commerce Township is 153.7 gal/day with 10% of high and low end account usage analyzed
People/ Household
Residential Accounts
4-Year Avg. Winter Use (Units/Qtr)
Avg. from Statistically
Reduced Data
Gal/day/ Household
Gal/person/ day
2.67 4,912 19.26 18.49 153.7 57.6
COMMUNITY WATER USAGE STANDARDIZED TO WASTEWATER FLOW NOT INCLUDING I/I
Community
People per Household
(SEMCOG 2013)
Water Use Derived from Analysis
(Gal/Person/Day)
Water Use Derived from Analysis
(Gal/Household/Day)
80% Wastewater Use Derived from Analysis (Gal/Household/Day)
BINGHAM FARMS 2.05 91.3 187.2 149.8
BLOOMFIELD HILLS 2.43 83.8 203.6 162.9
COMMERCE TOWNSHIP 2.67 57.6 153.7 123.0
FARMINGTON HILLS 2.34 70.9 166.0 190.9
HIGHLAND TOWNSHIP 2.65 75.9 201.1 160.9
KEEGO HARBOR 2.31 58.2 134.6 107.7
LYON TOWNSHIP 2.76 65.4 180.4 144.3
OAKLAND TOWNSHIP 2.87 84.1 241.4 193.1
ORCHARD LAKE 2.73 69.4 189.3 151.4
OXFORD TOWNSHIP 2.79 61.4 171.4 137.1
ROYAL OAK TOWNSHIP 2.44 58.6 143.0 114.4
Weighted Average 2.49 69.2 172.2 137.8
COMMUNITY/INDUSTRY WASTEWATER USAGE GUIDELINE COMPARISON INCLUDING I/I
Community
People per Household (SEMCOG
2013)
Water Use Derived from Analysis
(Gal/Person/Day)
Wastewater Use Derived from
Analysis Including I/I
(Gal/Household/Day)
WRC (using 3.5 people per household)
(Gal/Household/ Day)
GLUMRB (Gal/House-
hold/Day)
Haestad Methods
(Gal/House-hold/Day)
Innovyze (Gal/House-
hold/Day)
USGS (Michigan Average)
(Gal/House-hold/Day)
USGS (U.S. Average)
(Gal/House-hold/Day)
Aquacraft, Inc.
(Gal/House-hold/Day)
BINGHAM FARMS 2.05 91.3 172.2 315.0 205.0 151.7 153.8 150.88 184.8 130.7
BLOOMFIELD HILLS 2.43 83.8 187.3 315.0 243.0 179.8 182.3 178.848 219.1 154.9
COMMERCE TOWNSHIP
2.67 57.6 141.4 315.0 267.0 197.6 200.3 196.512 240.7 170.2
FARMINGTON HILLS 2.34 70.9 152.7 315.0 234.0 173.2 175.5 172.224 211.0 149.2
HIGHLAND TOWNSHIP
2.65 75.9 185.0 315.0 265.0 196.1 198.8 195.04 238.9 169.0
KEEGO HARBOR 2.31 58.2 123.8 315.0 231.0 170.9 173.3 170.016 208.3 147.3
LYON TOWNSHIP 2.76 65.4 166.0 315.0 276.0 204.2 207.0 203.136 248.8 176.0
OAKLAND TOWNSHIP
2.87 84.1 222.1 315.0 287.0 212.4 215.3 211.232 258.8 183.0
ORCHARD LAKE 2.73 69.4 174.2 315.0 273.0 202.0 204.8 200.928 246.1 174.1
OXFORD TOWNSHIP 2.79 61.4 157.7 315.0 279.0 206.5 209.3 205.344 251.5 177.9
ROYAL OAK TOWNSHIP
2.44 58.6 131.6 315.0 244.0 180.6 183.0 179.584 220.0 155.6
Weighted Average 2.49 69.2 158.4 315.0 249.0 184.3 186.8 183.3 224.5 158.8
PHASE I DATA ANALYSIS
A Steering Committee was formed to:
Review the Phase I Report
Provide input on the updated Schedule of Unit Assignment Factors
Updated Single Family Residential Usage = 8,238.67 cf/yr
Over 50% less than the existing REU usage
Updated REU Value = 2,106 cf/quarter
Based on utilization of 95% of the usage being returned to the wastewater system & 5% infiltration and inflow contribution
1998 SCHEDULE REVIEW
The entire Schedule was reviewed based on current demographics & development trends
The Schedule was re-formatted to create ‘main categories’ (Auto; Food, Beverage & Retail; Personal care; etc.)
Some classifications were eliminated, while others were added for a total of 53 non-residential properties surveyed
PHASE II DATA ANALYSIS
The data collection goal for the Study was to collect up to 5 representative properties within each non-residential subcategory (for a total of 265 businesses)
Data collection included specific water usage data for the same Phase I study period of 2010-2013 during the winter months
Usage and business category data for Phase II included the original 11 WRC billing communities as well as the City of Novi & Bloomfield, West Bloomfield & Waterford Townships
Additional service use data was collected from SEMCOG, field visits & phone calls to the various business types to calculate non-residential REU unit factors
PHASE II DATA ANALYSIS
Service use data included:
Square Footage
Meter Size
Number of Fixtures
Number of Employees
Number of Seats (restaurants /
banquet halls)
Number of Students (schools)
Number of Beds (hospitals)
Number of Dentists (dental offices)
Number of Doctors (medical offices)
Number of Rooms/Seats (medical / dental offices)
Number of Gas Pumps (convenience stores)
Number of Stalls/Bays (auto service repair / car washes)
Several Factors Hampered Reaching the Desired Business Survey Goal:
Nail & Tanning Salons / Spas being housed in strip malls with no individual meter
Business Owners / Managers unwilling to provide information
Majority of the participating communities did not contain several business classes included in the survey
PHASE II DATA ANALYSIS
CONCLUSIONS & RECOMMENDATIONS
Regression Charts were developed for each business class:
Showing positive or negative correlation with water usage (R2 value)
Charts showing negative correlations will require further analysis by the Committee & WRC
Recommended Unit Assignment Factors were developed based on the R2 values for each service unit
A Summary Table was developed that compared:
The 1998 Schedule REU values with our recommended REU values
REU values per service unit
CONCLUSIONS & RECOMMENDATIONS
The Steering Committee provided input on the data & initial recommendations
REU values based on ‘number of employees’ was not preferred
In instances where no strong positive correlations could be made, a unit assignment factor was based on ‘per facility’.
BANQUET HALLS REGRESSION CHART
1998 Unit Factor 0.500 per 1,000 sq. ft. Updated Unit Factor 0.38 per 1,000 sq. ft. (R2 value = 0.8198) Recommended Unit Factor 0.18 per fixture (R2 value = 0.7232)
R² = 0.4161
R² = 0.8198
R² = 0.7232
R² = 0.5225
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Seats
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SQ. Ft./Employees/Fixtures
1,000 Square Feet
Employees
Fixtures
Seats
Linear (1,000 SquareFeet)
Linear (Employees)
Linear (Fixtures)
Linear (Seats)
Banquet Halls
BOWLING ALLEYS REGRESSION CHART
1998 Unit Factor 0.160 per alley Updated Unit Factor 0.32 per alley (R2 value = 0.5950) Recommended Unit Factor 0.36 per 1,000 sq. ft. (R2 value = 0.8198)
R² = 0.8198
R² = 0.609 R² = 0.595
R² = 0.6049
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1,000 Square Feet
Employees
Lanes
Fixtures
Linear (1,000 SquareFeet)
Linear (Employees)
Linear (Lanes)
Linear (Fixtures)
Bowling Alleys
DAY CARE / EARLY LEARNING REGRESSION CHART
1998 Unit Factor NA Updated Unit Factor NA Recommended Unit Factor 0.06 per child/student (R2 value = 0.898)
R² = 0.0367
R² = 0.0151
R² = 0.0312
R² = 0.0898
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SQ. Ft/Employees/Fixtures
1,000 Square Feet
Employees
Fixtures
Students
Linear (1,000 SquareFeet)
Linear (Employees)
Linear (Fixtures)
Linear (Students)
Daycare / Early Learning
QUICK SERVICE RESTAURANTS W/O DINING & PUBLIC RESTROOMS REGRESSION CHART
1998 Unit Factor 1.80 per restaurant Updated Unit Factor 1.00 per restaurant Recommended Unit Factor * 1.00 per restaurant (no strong positive correlations exist)
R² = 0.7873 R² = 0.7109
R² = 0.0031
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1,000 Square Feet
Fixtures
Employees
Linear (1,000 SquareFeet)
Linear (Fixtures)
Linear (Employees)
Restaurants w/o Dining & Public Restrooms
Purpose
Allows the user to input a custom value which is then applied against a linear trend to produce an REU value
Allows the user to choose the ‘best fit’ for water usage per business class
REU CALCULATOR APPLICATION
REU CALCULATOR APPLICATION
WRC will review the Phase I Report & Recommendations for approval
Possible collection of more usage data
Updated Schedule anticipated by Early Fall 2016
NEXT STEPS
THANK YOU!
Laura Gruzwalski Johnson & Anderson
4494 Elizabeth Lake Rd Waterford, MI 48328
248-681-7800 lgruzwalski@ja-engr.com
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