Case Studies in New England Cost Effective...
Transcript of Case Studies in New England Cost Effective...
Stormwater Utility Workshop
March 25, 2015
Case Studies in New England
Cost Effective Methods for Parcel Analysis
and Completing Comparisons/Evaluations
for Stormwater Utility Rate Structure Options
Presented by
Bethany Eisenberg, VHB
Josh Sky, VHB
Juli Beth Hinds, Birchline Planning LLC
Mark Wetzel, Ayer Public Works
Answering Rate & Revenue
Questions Efficiently
Goals
Remote Sensing Technology
Ayer Case Study
Protecting resources, maintaining systems, and compliance
with state and federal regulations
Developing a User-Fee-Funded Stormwater
Program (without the “u” word)
Making sure the fee/fund matches
the services provided
“Any charge system in which a customer’s bill is determined based on the
demands that the customer imposes on the system and the related
benefits and services enjoyed by the customer, with the revenues that are
raised dedicated to addressing the needs of the program.”
Making sure the services provided
(maintenance, equipment, labor,
capital projects) are balanced with
economic realities in the
Municipality
Technology advances have helped
make program development and
management easier – but not the
politics.
How can we answer the
“how much” questions
efficiently, so that a
potential fee-based
program can be
discussed realistically?
Remote Sensing
Remote Sensing
Uses remotely sensed data from satellite or
airborne sensors to interpret impervious cover,
instead of hand-digitizing plans or
interpolating from other records
Quickly evaluate visually and quantitatively the
area & location of impervious surfaces Image captures red, green, and blue bands of the
electromagnetic spectrum (visible light) and the Near Infrared
(NIR) spectrum used to differentiate land cover types, including
impervious surfaces and vegetation on the landscape.
Can use satellite and aerial images
– Ikonos, Quickbird, USDA NAIP
– Quickbird 4-band $65/sq km
– (w/100 sq km (38 sq mi) minimum purchase) – Better to get higher resolution - others for lower resolution
($35-55)
– Usually under $10k for most municipalities
City of South Burlington Remote Sensing
Image, True Color Composite – Quickbird
Satellite Image (July 2006)
City of South Burlington Aerial
Photograph Remote Sensing Image,
Near Infrared Spectrum (NIR)
Composite – USDA NAIP (May 2008)
Benefits
Cost effective!
Easy to link downloaded data to
municipal parcel and other GIS
data sets for analysis.
Has been evaluated for accuracy (University of Vermont & CCPRC 2002)
Can create parcel level
impervious maps (data layers) up
to and including setting &
charging stormwater fees
Easily asses changes in
impervious cover over time with
periodic re-flights
Main Issues:
Data Purchase:
• Accuracy - depends on quality of base image data (price difference
is about 40% between medium- and high-quality)
• Need 4-band imagery (red/green/blue/NIR)
• Need proper pixel size of the image relative to ground area
(optimal between six-inch and three-foot (one meter) pixel size.
Data Analysis:
• Angle of image, sparse vegetation, snow fields, compacted soil,
quarries all may be misinterpreted as impervious area
• Not completely automated – there will be labor time to process &
adjust (plus integration with utility billing)
• Accuracy of parcel data is biggest variable in how accurate the
overall assessment will be
• Plan on multiple field checks if used for actual billing!!!
City & Town of St Albans Project (2008)
City & Town of St Albans Project (2008)
Compacted soils, sparse vegetation will show up as impervious – a
community’s definition of “impervious surface” may or may not include
these areas
Once linked to parcel data, enables
parcel, ERU, fee & credit scenario analysis
Case Studies
Applications for rapid stormwater fee
assessment:
City of Burlington, VT
– Understand distribution
of impervious area by
property type
– Assess different ERUs vs
“ISU” (Impervious
surface units)
– Ultimately implemented
flat fee for SFR through
triplex and “ISU” for
Directly Assessed
Customers
Applications for rapid stormwater fee
assessment:
City & Town of St Albans, VT
– What are the revenue options for
a City-only, Town-only, or joint
City-Town stormwater utility?
– Rapid assessment of impervious
cover using NAIP
– Reasonably (!) good parcel data
– Identified crucial importance of
railroad-owned land as % of
impervious area & potential
impact on stormwater budgets
– Fee not implemented, but
analysis has helped with
development of MS4 programs
Case Study:
Ayer, Massachusetts
Ayer Stormwater Management Budgets
$2.39M sewer budget
$1.69M water budget
$0.52M solid waste budget
Proposing $312,000 for stormwater
Current Stormwater Budget $123,000 out of General Fund
Current budget does not support regulatory compliance
Not addressing aging infrastructure
More costly to address upgrades in crisis/emergency (i.e.
collapsed catch basins)
Town of Ayer Evaluation Process:
Preliminary
Town stormwater budget determined (compliance + maintenance)
Prepared preliminary parcel distribution Analysis and compared with
budget.. Rough cut fee identified
• Significant needs & inaccuracies with Town’s in parcel map,
infrastructure data
– Parcel maps & assessor data not linked
– Fitchburg State worked on mapping/GPS of storm drainage
infrastructure
Town of Ayer Evaluation Process
• Background work with Mass GIS zoning data layer to establish
classifications:
– Used Mass GIS zoning data layer merged with existing GIS
database.
– Mass GIS zoning simplified into commercial, residential and
industrial classification.
– Commercial and industrial properties further subdivided by
parcel size to assess percent impervious, create “tiers”
– Comparison made to Ayer Assessor’s database to ensure
general appropriateness of Mass GIS zoning data.
• As remote sensing data were integrated, continued to make
adjustments to parcel maps
Mass GIS, Montachusett RPC provided substantial help!
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Parcel Size Range (acres)
Ayer, MA Parcel Distribution by Lot Size
Frequency Cumulative %
Remote sensing imagery of residential
land/impervious cover in Ayer, MA
Impervious Surface Classification Sample
Ayer, MA | February 25, 2010
Town Fee Evaluation Three fee structures
prepared:
– “Straight” ERU
– ERU w/cap for parcels with
more than 10 acres of
impervious area
– Flat fee based on impervious
surface “intervals” (i.e.
parcels w/1-3 acres
impervious charged
$1000/year, etc.)
– One property-type based fee
structure was prepared
based on Mass GIS zoning
data; Properties were broken
down into residential,
commercial, industrial and
road.
Average lot size 0.2–2.0 acres
– 2,000 of the 2,458 parcels are in
this size range
Mean parcel size = 2.47 acres
Typical residential lot size is 0.5
acres with 20% impervious area
20% impervious area = 0.1 acres
= 4,356 sf
4,356 sf = 1 ERU
*note: Town Parcel Maps needed
updating for final calculations!
Various Options Easily Evaluated
1) TIERED RATE
STRUCTURE
2) ERU-BASED RATE STRUCTURE with
maximum of $3,600 per parcel
PROPERTY TYPE
PARCEL
COUNT Tiered Cost
Estimated Annual
Revenue # of ERUs Cost by ERUs
Estimated
Annual Revenue
Occupied Residential 1,693 $36 $60,948 1 $36 $60,948
Non-Residential < 1 acre 199
Varied by
ERU $35,460 1 to 10 $36 - $360 $35,460
Non-Residential 1 to 2.999 acres 78 $1,000 $78,000 10 to 30 $360 - $1080 $47,484
Non-Residential 3 to 5.999 acres 29 $1,400 $40,600 30 to 60 $1080 - $2160 $42,588
Non-Residential 6 to 8.999 acres 10 $1,800 $18,000 60 to 90 $2160 - $3240 $27,108
Non-Residential 9 to 11.999 acres 2 $2,200 $4,400 90 to 120
$3240 - $3600
max $7,200
Non-Residential > 12 acres 9 $2,600 $23,400 120 and up $3,600 $32,400
TOTALS2 2,020 $260,808
$253,188
Town parcel data required updating for final calculations to be considered accurate
It was critical to show various options to Town management as well as homeowners and
commercial/industrial property owners. Remote sensing and GIS images were notably beneficial in
explaining the impervious cover method to prospective ratepayers, enabling them to visualize directly
the basis for calculating fees.
Stormwater Utility Fee Calculations
by Incremental Impervious Area
Based on average residential impervious area
(Equivalent Residential Unit = ERU)
Larger areas in increments of the “ERU”
Evaluated range but settled on $3/month/ERU
Stormwater budget $312,000 year
Land Use
Impervious
Area (sf/ac)
Impervious
Area (sf/ac)
Fee
($/mo.)
Fee
($/yr.)
Residential 4,356 .1 $3 $36
(= 1 ERU)
Small Commercial 43,560 1 $30 $360
Larger Commercial 435,600 10 $300 $3,600
Takeaways:
Remote sensing offers a cost-effective way to make the
potential budgets and fees “real,” and to improve the quality
and accuracy of the discussion
Even if a fee-based program ultimately is not adopted,
mapping has multiple uses:
– Environmental management
– Planning
– Assessing tree canopy, vegetated conditions in watersheds
Still requires skilled GIS technical skills – which can come
through Regional Planning Commission or University
partnerships, in-house, or consultants
Bethany Eisenberg | [email protected] | 617.607.1852
Juli Beth Hinds | [email protected]| 802.324.5760
Mark Wetzel | [email protected] | 617.607.1852
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Offices located throughout the east coast