EPA 910/9-81-084
&ER&
United States
Environmental Protection
Agency
Region 10
1200 Sixth Avenue
Seattle WA 98101
EPA-10-ID-Boise/Eagle-Ada-WWTW-81
Environmental Impact
Statement Appendices
Draft
Wastewater Management for
Boise, Eagle,
and Ada County, Idaho
-------
TABLE OF CONTENTS
APPENDIX A - EMISSION INVENTORY AND FORECASTING PROCEDURES
APPENDIX B - FISCAL OVERVIEW ON ADA COUNTY
APPENDIX C - POPULATION PROJECTIONS FOR ADA COUNTY EIS
ANALYSIS
APPENDIX D - DRAINAGE
APPENDIX E - PARTIAL SPECIES LIST, ADA COUNTY
APPENDIX F - HOURLY CARBON MONOXIDE EMISSIONS BY COMMUNITY
PLANNING AREA: 1977, 1980, 1987 and 2000
APPENDIX G - SUMMARY OF EXISTING CARBON MONOXIDE MONITORING
DATA
APPENDIX H - PROCEDURES USED TO EVALUATE FUTURE AIR POLLUTION
POTENTIAL IN ADA COUNTY
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Appendix A
EMISSION INVENTORY AND
FORECASTING PROCEDURES
Prepared by:
Jones & Stokes Associates, Inc,
2321 P Street
Sacramento, CA 95816
January 1981
-------
TABLE OF CONTENTS
INTRODUCTION A-l
HIGHWAY TRAFFIC EMISSIONS A-3
Summary of Traffic Model Characteristics A-3
Emission Calculation Procedure A-4
Default Parameter Inputs to MOBILE I A-7
Temperature A-7
Vehicle Speed A-9
Vehicle Age Distribution A-9
Age-Dependent Annual Mileage A-9
Hourly Percent ADT A-9
Directional Split A-13
Vehicle Fleet Mix A-13
Vehicle Operating Mode' A-13
PARKING ACTIVITY EMISSIONS A-16
Basic Approach A-16
Parking Facility Data Files A-16
General Calculation Procedure A-l9
Equations and Default Parameter Values A-25
Default Vehicle Movement Patterns A-32
RESIDENTIAL FUEL COMBUSTION EMISSIONS A-44
-REFERENCES CITED A-4 8
A-l
-------
LIST OF TABLES
Table Page
1 Highway Projects Added to 1975 Conditions A-5
to Develop Traffic Model Network for
Future Years
2 Default Temperature Pattern for the Boise A-8
Area
3 Default Speed Values Used for the Highway A-10
Emission Model
4 Vehicle Age Distribution Used in the High- A-ll
way Emissions Program
5 Parameter Values Specified as a Function A-12
of Time-of-Day and Roadway Speed Group
6 Average Vehicle Fleet Composition in the A-14
Boise Area
7 Parameter Values for Surface Lot Test A-21
Case Analyses
8 Parking Garage Evaluation Assuming 2, 3, A-22
and 4 Levels With a Single Entrance on
the First Level
9 Percent Idling Incorporated into MOBILE 1 A-24
Emission Rates at Various Speeds
10 Parameters Used in the Parking Emissions A-26
Model
11 Parameter Designations Used in the Computer A-27
Program
12 Equations in the Parking Emissions Model A-29
13 Parameter Values Defined as a Function A-30
of Total Parking Spaces and/or Parking
Facility Type
14 Default Temperature Pattern for the Boise A-31
Area
15 Default Operating Mode Parameters A-33
A-iii
-------
Table
16
17
19
20
21
22
List of Tables, Cont'd.
Page
Percent of Boise Vehicle Fleet Expected A-34
to be Equipped With Catalytic Converters
Default Guidance for Parking Duration A-36
Category and Parking Activity Index
Assignments
Characteristics of Short-Term Parking A-37
Movement Patterns
Characteristics of Intermediate-Term A-38
Parking Movement Patterns
Characteristics of Long-Term Parking A-39
Movement Patterns
Default Parking Movement Patterns A-40
Data and Assumptions Used for Estimating A-45
Carbon Monoxide Emissions From Residential
Fuel Combustion Sources
LIST OF FIGURES
Figure
1
Geographic Coverage of Off-Street Parking
Inventory
Page
A-18
A-iv
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EMISSION INVENTORY AND FORECASTING PROCEDURES
Introduction
Most air quality management activities involve the control
of pollutant emissions from various sources. It is important,
therefore, to have reasonable estimates of current and future
emissions so that effective air quality management programs
can be designed. It is usually impractical to attempt direct
measurement of pollutant emissions from all sources in an
urban area. Emission inventories (estimates of historical
or current emissions) and forecasts (projections of future
emissions) are usually prepared by extrapolating emission
rate data to local conditions. Depending on the emission
sources being considered, available emission rate data will
usually reflect a limited amount of direct emission measure-
ments plus calculations based on various assumptions.
Carbon monoxide emissions have been estimated for several
groups of emission sources in northern Ada County. The greatest
attention has been devoted to sources in the Boise metropolitan
area, since air quality monitoring data have documented
serious carbon monoxide problems throughout the Boise area.
Emission estimates have been structured to reflect historical
conditions for 1977 and 1980, and expected conditions for
1987 and 2000. Three broad categories of emission sources
have been evaluated: vehicle traffic on major roadways,
on- and off-street vehicle parking activity, and residential
fuel combustion for space heating or appliance-operation.
Commercial and industrial fuel combustion emissions have
not been estimated. Data for residential fuel combustion
suggest that commercial and industrial sources are probably
insignificant. Drive-up window facilities have not been
directly evaluated for the emission inventories and forecasts
discussed here. Data for parking facilities suggest that
drive-up facilities may be significant localized emission
sources.
Emission inventory and forecasting procedures for vehicle
traffic and parking activity were computerized to allow de-
tailed evaluation of geographic and temporal emission patterns.
Residential fuel combustion emission estimates were not
computerized.
The highway traffic and parking activity emission fore-
casting procedures involve a series of interrelated computer
programs that are linked to a single main program. Both
the highway traffic and parking activity analyses used the
A-l
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MOBILE 1 computer program to determine vehicle emission rates.
The MOBILE l"program (EPA 1978b) was modified to perform
an altitude interpolation procedure.
The MOBILE 1 program is designed to estimate vehicle
emissions for either low altitude (near sea level) or high
altitude (over 4,000 feet) conditions. Boise is at an ele-
vation of about 2,700 feet. The altitude interpolation pro-
cedure was accomplished through interpolation of values in
the "block data" section of MOBILE 1. The interpolation
procedure was applied to the following MOBILE 1 parameter
tables: new vehicle exhaust emissions, exhaust emission
deterioration rates, new vehicle idle emissions, idle emis-
sion deterioration rates, and the speed correction factor
coefficients. The specific interpolation procedure used
for the Boise area is given below.
B = L + (0. 63) (H - L)
Where: B = Parameter value for Boise (2,700 feet)
L = Low altitude parameter value (500 feet)
H = High altitude parameter value (4,000 feet)
A consistent set of population, land use, and employment
projections (Ada Planning Association 1978) has been used
as a base for all emission inventories and forecasts. The
Boise area traffic model also uses these same projections.
The various parameter inputs required for the highway traffic
and parking emissions forecasts were developed in consultation
with staff from the U. S. Environmental Protection Agency
(EPA), Idaho Air Quality Bureau, and Ada Planning Association
(APA). In most cases, however, final parameter values were
established by Jones & Stokes Associates staff. Actual com-
puter programming was performed by COMSIS Corporation. The
resulting computer programs were installed on the Idaho Trans-
portation Department computer system (IBM 370/158).
The computer programs developed for Boise contain one
feature which greatly reduces program execution time. Emission
rates (grams per mile factors) calculated by the MOBILE 1
program are stored for repeated use. This avoids the neces-
sity of executing the complete MOBILE 1 program for each
highway link or parking facility movement.
The discussions that follow focus on data sources, key
assumptions, and general calculation procedures. The intent
is to allow an independent and critical evaluation of the
resulting emission forecasts. These discussions are not
intended as a manual for performing actual computer runs.
For simplicity, the following descriptions will treat the
highway traffic and parking components as if they were separate
procedures. As noted above, they were actually incorporated
into a single main computer program to simplify the linkage
to the modified MOBILE 1 program.
A-2
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Highway Traffic Emissions
Most carbon monoxide emission inventories and forecasts
focus on emissions from highway traffic. Since the intro-
duction of the MOBILE 1 program, many state and local agencies
have approached this task by linking the MOBILE 1 program
to traffic model output. Previous emission inventory efforts
in Ada County (Benesh and Wiltsee 1979) utilized a portion of
the APRAC 2 program for this purpose. The emissions module
in the APRAC 2 program provides a geographical distribution
of emissions only in terms of a user-specified grid network.
Most land use and transportation planning activities of APA
are correlated with community planning areas and component
traffic zones.
Although the APRAC 2 program was available to APA staff,
uncertainties regarding its use led to consideration of other
approaches. The HWYEMIS 1 program was obtained from the
Federal Highway Administration. This program proved reasonably
easy to use, although the version received had some program
errors. A major limitation of the HWYEMIS 1 program is its
use of four fixed time intervals for providing emission inventory
output. These time intervals do not correspond to the times
when Boise experiences violations of the federal 8-hour carbon
monoxide standard. Data inputs to HWYEMIS 1 can be manipulated
to obtain emissions for any desired time period, but this
is a bothersome procedure.
A decision was eventually made to develop a new program
oriented toward hourly emission calculations with multiple
geographic output formats. The resulting program operates
in much the same way as the APRAC 2 emissions module, HWYEMIS
1, and similar programs. Traffic model output is taken on
a link-by-link basis, combined with input of other essential
data assumptions, and used to run the MOBILE 1 program.
Resulting emission calculation results are then stored for
later aggregation into the desired output format.
Summary of Traffic Model Characteristics
The traffic model for northern Ada County uses a system
of 237 traffic zones. The Boise Metropolitan Area is divided
into 148 zones while the remaining areas of northern Ada
County are treated as 73 zones. The remaining 16 zones repre-
sent traffic from outside the northern Ada County area.
Traffic zones in the metropolitan area average about 450
acres in size, with rural areas represented by larger zones
than those used for the City of Boise. Traffic zones in
the remainder of northern Ada County vary considerably in
size, depending on the extent of development. Overall, these
zones average about 4,900 acres in size. The existing high-
way network in the traffic model is represented by 1,278
highway segments (links) averaging about 0.42 mile in length.
A-3
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The traffic model is based largely on standard Urban
Transportation Planning System (UTPS) computer programs
(COMSIS Corporation 1978) . The trip generation component
is based on three internal trip types (home-based work [HBW],
home-based other [HBO], and nonhome based [NHB]) and two
external trip types (production internal/attraction external
[PI-AX] and production external/attraction internal [PX-AI]).
Trip generation rates are based on socio-economic character-
istics of each traffic zone in the model. Person-trips are
converted to vehicle-trips using an average vehicle occupancy
factor of 1.33 for HBW, HBO, and NHB trips and a factor of
1.67 for PI-AX and PX-AI trips.
Trip attractions are developed by traffic zone primarily
on the basis of employment categories and number of dwelling
units in the zone. A "special generators'1 program accounts
for hospitals, shopping centers, schools, the airport, and
the Boise State University campus. A balanced matrix of
zone-to-zone trip productions and attractions is eventually
produced. The traffic model does not account for trips occur-
ring entirely within a single traffic zone. The generally
small size of traffic zones in the urbanized area of the
county makes such intrazonal trips a minor component of overall
travel patterns.
Trips are assigned to specific roadways by normal "gravity
model" procedures. These procedures consider overall travel
times (a function of distance and speed) for alternative
routes between particular pairs of traffic zones. The model
currently uses three iterations of a "capacity restraint"
process to account for traffic congestion in evaluating alter-
native trip routes. This capacity restraint process reduces
assumed vehicle speeds according to a volume/capacity ratio
technique.
The traffic volumes assigned to specific roadways by
the model are in general agreement with observed traffic
patterns. Inaccuracies in traffic assignments on some road-
ways are, of course, inevitable. When emissions are aggregated
by community planning area, overall inaccuracies are minimized.
The highway network initially established for the traffic
model represented 1975 conditions. This 1975 network was
used for 1977 conditions also. The highway network used
for 1980 conditions was updated to reflect highway projects
completed since 1975. Additional highway projects were assumed
for the 1987 and 2000 networks (Table 1) .
Emission Calculation Procedure
The traffic model supplies only a small portion of the
data needed as input to the MOBILE 1 program. Most parameter
inputs for MOBILE 1 must be provided from another source.
The highway links in the traffic model are categorized by
A-4
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Table 1. Highway Projects Added to 1975 Conditions to
Develop Traffic Model Networks for Future Years
Year
1977
1980
i
en
1987
Projects Added to Network
For Previous Year
Southeast Corridor
Overland Road
Emerald Extension
Milwaukee
State Street Widening
Franklin Road
Southeast Corridor
Overland Road
State/Jefferson
Idaho and Main Closures
Bannock Street
East Boise Avenue
9th Street and Capital
Vista Avenue
State Street
10th Street Reversal
Chindcn-Broadway Interim
Connection
Meridian Interchange
Comments
No projects added to 1975 network
Broadway to Pennsylvania
Widen from two lanes to four lanes between Curtis
and Cole
From Cole to Maple Grove
From Ustic to Franklin Road
Six lanes, 23rd to 27th; left turn bays, 27th to
36th
Widen to four lanes with left turn bays, Cole to
Maple Grove and Orchard to Curtis
Four lanes, Pennsylvania to Apple Street to Boise
Avenue
Widen to five lanes, Orchard to Curtis
Reverse one-way flows, 16th to 1st Streets
Block off both streets between Capital and 9th
Street
Reverse flow from 2nd to 16th Streets
Widen to four lanes, Gekler to Greenwood
Establish one-way couplet system around City
Center project
Signalization and intersection improvements,
Ridenbaugh Canal to Federal Way
Widen to five lanes, 36th Street to Glenwood
Reverse one-way flow, Front Street to State
Street
Extend Myrtle to Main/Fairview and provide interim
connection to Main/Fairview couplet
Extend Front Street to Broadway
Construct Southeast on-ramp to I-80N
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Table 1 (cont'd.)
Year
2000
i
(Tl
Project Added to Network
For Previous Year
Highway 21
Eagle Road Bypass
13th Street
Boise River Crossing
Southeast Corridor
Vista Avenue
Chinden-Broadway
Connection
Rosehill/Franklin Road
Bannock Street Extension
Glenwood Extension
State Street
Franklin Road
15th/16th couplet
State Street/Jefferson
couplet
Comments
Relocate Highway 21, Diversion Dam to Gowen
Road interchange
Construct bypass of Highway 44 on south side
of Eagle
Change to two-way traffic between Front and
Borah
New river crossing between existing Fairview/
Main and Glenwood bridges
Entire project, including both the east and
west crossings of the Boise River
Widening to four lanes and other improvements,
Overland to Malad
East-west connection between Chinden Boulevard
and Broadway Avenue
Intersection improvement and widening
From 16th Street to Main
From Mountain View to Cole Road
Widen from 36th to Glenwood
Widen, Curtis to Cole
One-way couplet, Front to Shoreline
Complete Avenue B portion at east end of project;
improvements at west end of project
SOURCE: Nelson 1981.
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a facility type code and an area type code. The traffic
model assigns free-flow speeds and hourly lane capacities
on the basis of these facility type-area type combinations.
These same facility type-area type codes were used to classify
all roadway links into one of three speed-based categories
for the highway emissions program:
o High speed roadways with free-flow speeds of
50-57.5 mph; median = 53.8 mph
o Medium speed roadways with free-flow speeds of
30-47.5 mph; median = 38.8 mph
o Low speed roadways with free-flow speeds of
15-27.5 mph; median = 21.3 mph
Different sets of MOBILE 1 parameters were developed
for each of these three roadway groups.
The program for calculating highway traffic emissions
analyzes traffic model output on a link-by-link basis. For
each link, emissions are calculated on an hourly basis. Average
daily traffic volumes from the traffic model are factored
into hourly volumes. For two-way streets, these hourly volumes
are further split by direction. Volume/capacity ratios and
a default speed table are used to calculate a weighted average
speed for the total traffic volume on the link. This weighted
average speed, the total hourly volume, the length of the
link (from the "historical record" data file of the traffic
model), and various other parameter inputs are used with
the MOBILE 1 program to calculate vehicle emissions on the
link. The weighted average speed computation was used to
reflect the directional split of hourly traffic (and resulting
differences in traffic congestion) without doubling the number
of MOBILE 1 calculations required for the emissions program.
Default Parameter Inputs to MOBILE 1
Temperature. A default hourly temperature curve was
established in consultation with the Idaho Air Quality Bureau
(Table 2). The MOBILE 1 program does not accept temperatures
below 0°F. The adopted temperature curve is considered repre-
sentative of a cold winter day in Boise, but is not based
on any statistical analysis of daily temperature records.
A-7
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Table 2. Default Temperature Pattern for the Boise Area
Clock
Hour
1
2
3
4
5
6
7
8
9
10
11
12
Temperature
(°F)
0
0
0
0
0
0
2
6
8
10
12
14
Clock
Hour
13
14
15
16
17
18
19
20
21
22
23
24
Temperature
' (°F)
16
18
20
18
16
14
12
10
8
6
4
2
Notes: Clock hours are designated by the end of the hour.
Thus, hour 8 = 7:00 a.m. to 8:00 a.m. and hour 17 = 4:00 p.m.
to 5:00 p.m.
A-i
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Vehicle Speed. The traffic emissions program is structured
to obtain the speed input to MOBILE 1 from any of three sources:
o From a default speed table based on volume capacity
ratios.
o From a default table giving fixed speed values based
on time of day.
o From the traffic model link data files.
All emissions inventory and forecast work has used the
first option (Table 3). The second option was considered
too arbitrary. The third option seems, on the surface, to
be the most logical procedure. The traffic model, however,
is oriented primarily toward daily traffic volumes. The
speed values listed in the historical record data file are
not directly applicable to any specific hourly flow volume.
Vehicle Age Distribution. Previous emission inventory
work for the Boise area (Benesh and Wiltsee 1979) established
a vehicle age distribution table for the Boise area (Table 4).
This table was based on vehicle registration data for Ada
County (apparently for 1977). The national average default
age distribution contained in the "block data" section of
the MOBILE 1 program has been replaced by the data in Table 4.
Age-Dependent Annual Mileage. The national average
default values were used for the vehicle age-dependent annual
mileage accumulations. Data specific to the Boise area were
not readily available.
Hourly Percent APT. The average daily traffic (ADT)
values generated by the traffic model are converted by the
emissions program into hourly traffic volumes. Default values
for the three roadway categories are shown in Table 5 (PCTADT).
The values for high speed roadways are taken from Benesh
and Wiltsee (1979). The values for medium and low speed
roadways were developed from traffic count data provided
by the Idaho Transportation Department (ITD). Daily traffic
counts for December 1975, November 1976, December 1977, and
November 1978 were used. Four count stations were used to
develop the medium speed roadway data:
o State Street (Highway 44) between 23rd and 24th
Streets.
o Fairview Avenue at the Boise River Bridge.
o Main Street at the Boise River Bridge.
o Broadway Avenue at the Boise River Bridge.
Three count stations were used to develop the low speed
roadway data:
o Warm Springs Avenue (Highway 21) between Walnut
and Locust.
A-9
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Table 3. Default Speed Values Used for the
Highway Emissions Model
Speed Values (mph)
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
1.
1.
1.
1.
1.
1.
1.
1.
1.
1.
2.
2.
2.
2.
2.
V
75C
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
4
High Speed
Roadways
53.
53.
53.
53.
53.
53.
53.
50.
49.
46.
44.
41.
37.
34.
30.
27.
23.
20.
18.
15.
13.
11.
10.
9.
8
8
8
8
8
8
8
7
0
8
1
0
7
1
6
1
9
9
2
8
7
9
4
0
Medium
Speed
Roadways
38.
38.
38.
38.
38.
38.
38.
36.
35.
33.
31.
29.
27.
24.
22.
19.
17.
15.
13.
11.
9.
8.
7.
6.
8
8
8
8
8
8
8
6
3
7
8
6
2
6
1
6
2
1
1
4
9
6
5
5
Low Speed
Roadways
21.
21.
21.
21.
21.
21.
21.
20.
19.
18.
17 .
15.
14.
13.
12.
10.
9.
8.
7 .
6.
5 .
4 .
4 .
3 .
3
3
3
3
3
3
3
1
4
5
5
2
9
5
1
/
5
3
2
3
4
7
1
6
Notes: Speed values calculated from the following equations:
When Y >_ 0.8-.
0.75C ~
S1 = S0 7 (1 +
Where:
S1 = adjusted speed
so = free flow speed assigned to roadway group
V = link17 V°1Ume f°r d sPecified direction on a highway
C = hourly capacity of the highway link for the specified
r
A-10
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Table 4. Vehicle Age Distribution Used in the Highway Emissions Program
Vehicle age (years)
10 11 12 13 14 15 16 17 18 19 20+
IDA 0.045 0.086 0.087 0.066 0.083 0.090 0.086 0.069 0.065 0.062 0.054 0.047 0.040 0.039 0.028 0.010 0.014 0.008 0.006 0.004
IDT 0.036 0.081 0.080 0.065 0.077 0.094 0.083 0.057 0.060 0.059 0.051 0.042 0.042 0.038 0.033 0.026 0.021 0.015 0.016 0.025
MOT 0.036 0.081 0.080 0.065 0.077 0.094 0.083 0.057 0.060 0.059 0.051 0.042 0.042 0.038 0.033 0.026 0.021 0.015 0.016 0.025
HDG 0.096 0.069 0.067 0.107 0.130 0.102 0.062 0.057 0.063 0.042 0.037 0.037 0.028 0.018 0.016 0.014 0.009 0.008 0.006 0.024
HDD 0.095 0.093 0.057 0.102 0.119 0.096 0.061 0.054 0.063 0.044 0.037 0.038 0.033 0.023 0.016 0.014 0.008 0.008 0.007 0.039
MC 0.030 0.074 0.079 0.134 0.135 0.144 0.108 0-094 0.075 0.050 0.030 0.024 0.023
Notes:
LDA - light duty autos
LOT - light duty trucks
MDT - medium duty trucks
HDG - heavy duty gasoline-powered vehicles
HDD - heavy duty diesel-powered vehicles
NC - motorcycles
SOURCE: Benesh and Wiltsee 1979.
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Table 5.
Parameter Values Soecified as a Function of Time-of-Day and Roadway Speed Group
12
15
17
23 21
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2 24.6 24.8 24.8 24.8 24.8 24.8 24.8 2'.0 24.0 19.7 1°.7 19.8 19.8 19.8 19.3 19.8 24.0 24.0 24.3 24.8 24.8 24.8 24. S 24.6
3 0.5 0.5 0.5 0.5 0.5 0.5 0.5 1.6 1.6 7.1 7.1 7.1 7.1 7.1 7.1 7.1 1.5 1.5 0.5 0.5 0.5 0.5 0.5 0.5
4 0.9 0.9 0.9 0.9 0.9 0.9 0.9 3.1 3.1 14.1 14.1 14.1 14.0 14.0 14.0 14.0 3.1 3.1 0.9 0.9 0.9 0.5 0.5 0.5
5 0.7 0.7 0.7 0.7 0.7 0.7 0.7_0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7 0.7
6 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 "~ 0.9 " 0.9" 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9 0.9
P-.TCNO 1 25.0 25.0 25.0 25.0 25.0 25.0 25.0 35.0 35.0 30.0 30.0 30.0 30.0 30.0 30.0 30.0 35.0 35.0 25 0 25 0 25 0 25 0 25.0 25.0
2 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 5.0 10.0 10.0 10.0 10.0 10.0 10.0
3 60.0 60.0 60.0 tO.O 60.0 60.0 60.0 65.0 65.0 70.0 70.0 70.0 70.0 70.0 70.0 70.0 75.0 75.0 60.0 60.0 60.0 60.0 60.0 6J . 0
NOTES: This table has been prepared using a computer printout from the traffic emissions
program.
Curve set 1 = parameter values for high speed roadways.
Curve set 2 = parameter values for medium speed roadways.
Curve set 3 = parameter values for low speed roadways.
PCTADT
PCTDIR
PCTVEH
hourly traffic volume as percent of average daily traffic volume
percent of hourly traffic volume heading toward downtown Boise.
vehicle fleet composition (percent):
1 = light duty autos 4 = heavy duty gasoline-powered vehicles
; - light duty trucks 5 = heavy duty diesel-powered vehicles
3 = medium duty trucks 6 = motorcycles
PCTCND = vehicle operating mode parameters (percent)
1 = noncatalyst vehicle VMT in a cold start mode (PCCO)
2 = catalyst vehicle VMT in a hot start mode (PCHS)
3 catalyst vehicle VMT in a cold start mode (PCCC)
A-12
-------
o Capitol Boulevard (Highway 30) at the Boise River
Bridge.
o 8th Street at the Boise River Bridge.
The hourly traffic volume factors listed in Table 5
represent weighted averages of winter weekday traffic condi-
tions for the months identified above. The traffic model
ADT estimates represent average weekday conditions. Emission
estimates for other conditions (weekends, holidays, summer,
etc.) could be generated by adjusting the traffic model ADT
values and/or the hourly percent ADT values.
Directional Split. Hourly directional split assumptions
are shown in Table 5 (PCTDIR entries). The values for high
speed roadways were taken from Benesh and Wiltsee (1979).
The values for both medium and low speed roadways were based
on the ITD traffic count data for Fairview Avenue and Main
Street.
Vehicle Fleet Mix. Benesh and Wiltsee (1979) made an
estimate of average freeway and nonfreeway vehicle fleet
compositions. The relative mixes of various truck categories
were adjusted by Jones & Stokes Associates staff to reflect
more realistic assumptions. The resulting average vehicle
fleet mixes (Ta,ble 6) were then used to develop the hourly
fleet mix values shown in Table 5 (PCTVEH values).
Hourly vehicle fleet mix assumptions were calculated
in consultation with various state and local agency staff.
The fleet mix for high speed roadways was kept constant for
all hours. The fleet mix for medium and low speed roadways
was adjusted in an attempt to reflect the concentration of
delivery truck activities during normal workday hours. The
overall daily fleet mix for these two roadway types (Table 6)
has been maintained in the hourly fleet mix values. This
was accomplished by recognizing the hourly traffic distribution
obtained from the ITD traffic count stations. The hourly
fleet mix values in Table 5 effectively allocate 82 percent
of the medium-duty and heavy-duty gasoline truck traffic
to the 9:00 a.m. to 4:00 p.m. time period.
Vehicle Operating Mode. The MOBILE 1 program calculates
separate emission rates for catalyst-equipped and noncatalyst
light- and medium-duty vehicles. The MOBILE 1 program then
uses the calendar year, the vehicle age distribution table,
and the age-dependent vehicle mileage data to calculate appro-
priate weighting factors and to generate age- and VMT-weighted
vehicle-type composite emission rates.
Because initial calculations are done separately for
catalyst-equipped and noncatalyst vehicles, vehicle operating
mode data must be specified separately for these two groups.
A-13
-------
Table 6. Average Vehicle Fleet Composition in the Boise Area
Vehicle Class
Light duty autos
Light duty trucks
Medium duty trucks
Heavy duty gasoline vehicles
Heavy duty diesel vehicles
Motorcycles
Average
High Speed
Roadways
68. 0%
15.5%
1.7%
8.0%
6. 6%
0.2%
Vehicle Mix
Low and Medium
Speed Roadways
67.5%
23.2%
2.6%
5.0%
0.7%
0.9%
DATA SOURCE: Modified from Benesh and Wiltsee 1979 by Jones & Stokes Associates
staff.
-------
The MOBILE 1 program recognizes three possible operating
modes for a vehicle: cold start, hot start, and hot stabilized.
The cold start mode represents the first 505 seconds of vehicle
operation following an engine-off period of at least 1 hour
for catalyst-equipped vehicles or at least 4 hours for a
noncatalyst vehicle. The hot start mode represents the first
505 seconds of vehicle operation following an engine-off
period of less than 1 hour for catalyst-equipped vehicles
or less than 4 hours for noncatalyst vehicles (assuming the
vehicle was in a hot stabilized mode prior to the engine-
off period). The hot stabilized mode represents all vehicle
operation occurring more than 505 seconds after the engine
is started.
Catalyst-equipped vehicles revert to a cold operating
mode after a much shorter parking duration than do noncatalyst
vehicles. Consequently, catalyst-equipped vehicles will
normally have a greater portion of total travel in a cold
start mode, and less in a hot start mode, than will noncatalyst
vehicles. Given similar travel patterns, catalyst-equipped
and noncatalyst vehicles will have the same portion of total
travel in a hot stabilized mode.
The MOBILE 1 program assumes identical vehicle age-
related travel patterns for catalyst-equipped and noncatalyst
vehicles. Consequently, specifying any three of the four
catalyst/noncatalyst cold start/hot start parameters allows
calculation of the cold start/hot start/hot stabilized para-
meters for both catalyst-equipped and noncatalyst vehicles.
The MOBILE 1 program input requirements specify the following
data inputs:
o PCCO = percent of noncatalyst vehicle VMT which
occurs in a cold start mode.
o PCHS = percent of catalyst-equipped vehicle VMT
which occurs in a hot start mode.
o PCCC = percent of catalyst-equipped vehicle VMT
which occurs in a cold start mode.
The traffic model provides data which can be used to
estimate the daily average hot stabilized VMT percentage
(equal for both catalyst-equipped and noncatalyst vehicles).
Splitting the remaining start mode VMT into cold start and
hot start components requires data or estimates of vehicle
parking duration patterns. Data and assumptions used for
the parking emissions model were used to generate the PCCO,
PCHS, and PCCC values shown in Table 5.
A-15
-------
Parking Activity Emissions
Emissions associated with vehicle parking activity are
not routinely accounted for in urban area emission inventories,
Consequently, there are few standardized procedures for evalu-
ating such emission sources. The EPA has published one
procedure for evaluating emissions from parking lots (EPA
1978a). The procedure in that report requires extensive
facility-specific engineering data. These data requirements
make the procedure impractical for areawide emission inventory
purposes.
The procedure described below was developed specifically
for areawide emission inventory purposes. Since parking
facilities are evaluated individually in this procedure, it
would also be useful for evaluating single parking facilities.
The following discussion consists of three major sections.
The first describes the general approach and overall compu-
tation sequence. The second section presents the specific
equations and data parameters used in the model. The pro-
cedure used for estimating vehicle parking activity is
described in the third section.
Basic Approach
The parking emissions model has been structured to link
a parking facility data file to a calculation procedure which
uses EPA's MOBILE 1 computer program to calculate vehicle
emission rates. Parking facilities are processed one at
a time. Vehicle activity at each parking facility is analyzed
on an hourly basis. Several categories of parking activity
are considered in the model: residential parking (home-
based vehicle trips), on-street parking in the downtown area
(mostly metered parking), off-street covered or open parking
lots, and parking garages.
Parking Facility Data Files. Two types of parking facility
data files were created. The Boise area traffic model was
used to generate a data file for home-based vehicle trips
(residential parking). This data file contains a single
entry for each traffic zone. A special data file had to
be created for the remaining on- and off-street parking faci-
lities. This was accomplished by using existing parking
survey data for the downtown area and by conducting special
parking surveys in other portions of the Boise metropolitan
area.
Each parking facility was coded as to type, location,
number of parking spaces, and general land uses served. The
location coding was based on the highway links and traffic
zones incorporated into the Boise area traffic model. The
special parking surveys were focused on major roadways and
A-16
-------
commercial centers in the Boise area. While the result
was less than 100 percent coverage of all off-street parking
in the Boise area, coverage is certainly greater than 80 percent.
Figure 1 shows the approximate geographic coverage of the
resulting parking facility data file.
The initial on- and off-street data file represented
1980 conditions. City and county permit files were used
to identify major parking lots constructed between 1977 and
1980. A 1977 data file was created by removing these faci-
lities from the 1980 data base. Data files for future condi-
tions were created in several steps. A "forecast base" inventory
was created from the 1980 data file by deleting those parking
facilities which will be removed during construction of the
Boise Redevelopment Agency's City Center Project. Four addi-
tional parking lots expected to be affected by other downtown
redevelopment were also deleted.
Forecasts of future parking facilities were made for
two time periods: 1980-1987 and 1987-2000. These were based
largely on employment projections contained in the population
and employment forecasts used by APA. These forecasts (APA
1978) are broken down by traffic zone for 5-year intervals
from 1975-2000. A 1987 employment forecast was interpolated
from the 1985 and 1990 data. For each traffic zone the percent
increase in employment (1980-1987 and 1987-2000) was used
to derive a first estimate of new parking spaces. These
spaces were allocated to various types and sizes of parking
lots based on three factors: the 1980 parking inventory,
the specific employment categories predicted by the employ-
ment forecast, and the predicted locations of future neighbor-
hood and community shopping centers (from the employment
forecast report).
The resulting forecasts were then adjusted to ensure
that they reflected several major construction projects
expected during the 1980-1987 time period. These major pro-
jects included the City Center project, expansion of the
Hewlett-Packard facility, expansion of the M-K development,
parking lot expansion at the airport, and several shopping
center projects identified by city and county staff but not
reflected in the 1978 population and employment forecasts.
The City Center project was treated as two separate
projects: a downtown shopping and office mall project and
a separate auditorium project. Parking for the mall project
was treated as a subterranean parking lot (1,414 spaces)
and two parking garages (5 levels with 1,110 spaces and 5
levels with 331 spaces). The auditorium parking was con-
sidered as a 4-level, 600-space garage.
A-17
-------
>
I
%%%%%%%S%%%%%%%6S £ '%ffiffl$$wi6
FIGURE 1. GEOGRAPHIC
COVERAGE OF OFF-STREET
PARKING INVENTORY
-LEGEND-
m AREA COVERED BY PARKING SURVEYS
-------
Projections of future residential parking activity were
compiled from the home-based vehicle trips generated by the
Boise area traffic model.
General Calculation Procedure. As noted above, the
parking model evaluates hourly vehicle movements within in-
dividual parking facilities. Within each parking facility,
available spaces are allocated to one of three parking dura-
tion categories: short-term parking (less than 1 hour),
intermediate-term parking (1 hour or more but less than
4 hours), and long-term parking (4 hours or more). This
parking duration split was made to facilitate determination
of vehicle operating mode parameters required for use of
the MOBILE 1 program.
Twenty groups of land use types were defined for cate-
gorizing parking facility usage patterns. Hourly entrance
and exit movement patterns were defined for each parking
duration category for each land use group. By assuming a
hypothetical 100 spaces, it was possible to define these
movement patterns as a percentage of available spaces. De-
pending on assumed parking duration, these movement patterns
were developed on 15-minute, 30-minute, or 1-hour time incre-
ments.
The parking model performs separate analyses of hourly
entrance and exit movements for spaces associated with each
parking duration category. Each vehicle movement is treated
as two components: vehicle travel to or from a parking space,
and an idle emissions adjustment to correct for insufficient
or excessive vehicle idling built into the basic MOBILE 1
emission rates.
Travel Component. Parking lots and garages do not fill
in any precise sequence unless entering vehicles are directed
to specific parking spaces. In general, drivers show a variety
of preferences in terms of available spaces -- nearest empty
space, close to an exit, close to the expected return route,
etc. Once a facility has substantially filled and starts
experiencing turnover of occupied spaces, the precise loca-
tion of vacant spaces is not easy to predict. Thus, vehicle
travel inside the facility can be reasonably estimated in
terms of a weighted average travel distance between the
facility entrance and the parking spaces. Since the move-
ment of exiting vehicles is largely determined by where the
entering vehicle parks, it is simplest to discuss basic pro-
cedures in terms of entering vehicles.
It is clearly impractical to calculate a weighted average
travel distance specific to each parking facility in an area-
wide inventory. The obvious alternative is to relate this
A-19
-------
distance to parking facility area. The simplest case would
be a small parking lot with one aisle. The average travel
distance in this case would be one-half the length of the
lot. For a square lot, this would be one-half the square
root of the parking lot area. Extending this logic, the
average travel path distance should be some value times the
square root of parking facility area.
Appropriate coefficient values for calculating average
travel'path distance were developed from detailed analyses
of a 4-level parkina garage in Sacramento, California and
the proposed underground parking facility for the Boise City
Center project. The Sacramento garage was used because site
plans for several parking garages in Boise could not be readily
located. Several test cases were developed from each set
of plans. Each level of the Sacramento garage was evaluated
as if it was a surface lot. In addition, the Sacramento
garage was evaluated as 2-, 3-, and 4-level structures. The
underground lot for the Boise City Center project was ana-
lyzed in its entirety and as several subsections.
The basic procedure used for each test case was to out-
line a "standardized travel path" from each facility entrance
to each parking aisle or row. A deliberate effort was made
to establish reasonable but not necessarily "shortest distance"
travel paths. The average travel path distance for vehicles
parking in each row or aisle was calculated as a fixed dis-
tance from the entrance to the head of the parking aisle
plus one-half the length of the parking aisle. The average
travel path distance for vehicles parking in the lot (or
on any garage level) was then determined by weighting these
standard travel path distances by the number of parking spaces
served.
Test case results are presented in Tables 7 and 8.
These results were used as guides in developing default para-
meter values for the parking emissions model. Separate
default coefficients were established for small lots (<100
spaces), intermediate lots (101-1,000 spaces), large lots
(>1,000 spaces), and multiple-level garages.
To account for vehicle travel while searching for a
parking space, average travel distances for entering vehicles
were assumed to be 30 percent greater than the average travel
path distance calculated above. The average travel path
distance was used for exiting movements.
Default values of gross area per parking space were
established for all parking garages and each size category
of surface lots, thus minimizing facility-specific data re-
quirements.
A-20
-------
Table 7. Parameter Values for Surface Lot Test Case
Analyses (Distances in Feet; Areas in Square Feet)
Facility Description
Sacramento Garage, Level 1
Sacramento Garage, Level 2
Sacramento Garage, Level 3
Sacramento Garage, Level 4
BRA Facility, Subterranean
Level, Grove & Capitol Entrance
South Section, BRA Facility
Entrance Opposite Grove St.
South Section, BRA Facility,
Front St. Entrance
" South Section, BRA Facility,
M Both Entrances Averaged
Middle Section, BRA Facility
Spaces
215
230
204
116
1,445
841
841
841
509
Area
88,
93,
82,
42,
644,
331,
331,
331,
206,
912
569
984
858
818
680
680
680
774
Area Per
Space
414
407
407
369
446
394
394
394
406
Average Travel
Path Distance
350
356
325
172
1,012
690
615
653
455
F
1
1
1
0
1
1
1
1
1
Value
.174
.164
.128
.831
.260
.198
.068
.133
.001
NOTES:
BRA = Boise Redevelopment Agency.
-"•Based on test case equation: D = F Varea; where D = average travel path distance and F = co-
efficient value.
-------
Table 8. Parking Garage Evaluation Assuming 2, 3, and 4 Levels
With a Single Entrance on the First Level
(Distances in Feet; Areas in Square Feet)
Number of Area Per
Garage Levels Spaces Area Space
Two Levels 445 182,481 410
Three Levels 649 265,465 409
Four Levels 765 308,323 403
Average Pamp
Distance
261
518
690
.0
.4
.8
Within Level
Travel1
353.
344.
318.
1
3
1
Total Travel
Path I
614. 1
862.7
1,008.9
F Value
1.438
1.674
1.817
NOTES:
1Weighted average according to parking spaces on component garage levels.
2Based on test case equation: D = F Varea; where D = total travel path
•f length and F = coefficient value.
NJ
N)
-------
MOBILE 1 emission rates are used to estimate emissions
from vehicle travel within a parking facility. A uniform
vehicle mix was used for all parking facilities and all hours.
For the Boise application, temperature inputs to MOBILE 1
vary by hour (0°-20°F range). Vehicle speeds of 5, 7, and
10 mph were assigned as a function of facility size. Hourly
operating mode parameters (catalyst and noncatalyst vehicle
cold starts and catalyst vehicle hot starts) were established
separately for entering and exiting vehicles for each parking
duration category. Catalyst and noncatalyst vehicle cold
start percentages for vehicles using short-term parking spaces
reflect the extent to which trips in the Boise area are com-
pleted while still in a cold start mode.
Idling Adjustment. The idling adjustment step intro-
duced significant complexity into the parking emissions model.
As applied in Boise (or any other cold weather area), it
accounts for a substantial fraction of total parking emissions.
The initial step in the idle adjustment procedure re-
quired setting a maximum on the amount of idling time for
entering vehicle movements, and a minimum for exiting vehicle
movements. Home-based vehicle trips and on-street parking
were treated as exiting vehicle movements only. Entering
and exiting idle threshold values (seconds of idling) were
set separately for garages, surface lots, on-street parking,
and home-based trips.
The amount of idling emissions built into MOBILE 1 varies
as a function of vehicle speed. At low speeds, the MOBILE 1
emission rates assume that idling accounts for 30-45 percent
of vehicle operating time (Table 9).
In analyzing the hourly entering and exiting vehicle
movements at a parking facility, the model calculates the
seconds of idling accounted for by the MOBILE 1 emission
rates. This value is compared to the appropriate idle thres-
hold value to determine an appropriate idle adjustment factor.
For entering vehicle movements, the idle adjustment factor
represents any excessive idling inherent in the MOBILE 1
rates (idling built into MOBILE 1 > entering vehicle idle
threshold value). For exiting vehicle movements, the idle
adjustment factor represents insufficient idling inherent
in the MOBILE 1 rates (idling built into MOBILE 1 < exiting
vehicle idle threshold value).
The idling emission rates calculated by the MOBILE 1
program are not an adequate basis for analyzing idle emis-
sions in a parking lot. The MOBILE 1 idle emission rates
represent a hot stabilized operating mode. Much vehicle
activity in a parking facility, however, will occur in a
A-2 3
-------
Table 9. Percent Idling (Time Basis) Incorporated
MOBILE 1 Emission Rates At Various Speeds
Into
Nominal
Speed
(ir.ph)
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
Percent
Idle
45.
43.
40.
38.
35.
32.
31.
29.
28,
26.
25.
23.
22.
21.
19.
18.
16.
15.
15,
14.
13.
, 78
, 23
, 67
. 11
.55
.99
,06
.64
.22
. 80
. 38
96
.48
,00
53
,05
75
, 97
.20
.43
.66
Nominal
Speed
(mph)
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
Percent
Idle
12.
12.
11.
11.
10.
9.
9.
8.
7.
6.
6.
5.
4.
4.
3.
3.
2.
2.
2.
2.
97
32
67
02
37
70
02
34
67
99
30
62
93
24
55
05
88
72
56
40
Nominal
Speed
(mph)
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
Percent
Idle
2
2
2
2
2
2
2
2
2
1
1
1
1
1
1
. 37
. 39
.40
.42
.4-4
.43
.32
.21
.10
. 99
.58
.77
.66
. 55
.44
DATA SOURCE:
Based on linear interpolation of percent tima at idle vs. (actual) averace speed given in
Table 5-2 of Smith and Aldrich 1977.
A-24
-------
cold start or hot start mode (all exiting movements plus
entering movements for vehicles reaching the facility after
a short trip duration).
Hot start idle emission rates were assumed to be the
same as the MOBILE 1 hot stabilized idle rate. Cold start
idle emission rates were estimated from 100 percent cold
start (PCCO = PCCC = 100.0; PCHS = 0.0) running emissions
at 5 mph. The 5 mph cold start emission rates from MOBILE 1
were converted to a grams per minute basis and used as a
cold start idle rate (generally about 2.5-3.5 times the hot
stabilized idle rate). A weighted cold/hot idle emission
rate factor was calculated from the cold start and hot
stabilized idle rates, weighting these components according
to the fraction of vehicles entering or exiting the facility
in a cold start mode.
The fraction of vehicles entering or exiting in a cold
start mode was itself calculated as a weighted average of
the catalyst and noncatalyst cold start percentages for the
hour being analyzed.
Total Emissions. Emissions from entering and exiting
vehicles were computed separately as the sums of travel com-
ponent emissions and the appropriate idle adjustment emissions.
For entering vehicles, the idle adjustment was either zero
or a negative value. For exiting vehicles, the idle adjust-
ment was either zero or a positive value. Most parking faci-
lities did not require any entering vehicle idle adjustment,
but did require an idle adjustment for exiting vehicles.
Emissions from on-street parking and home-based trips
were treated as idling emissions during vehicle warm-up.
This was accomplished by using the exiting vehicle idle
adjustment computation.
Equations and Default Parameter Values
Variables used in the parking emissions model are listed
in Table 10. The designation of these variables in the computer
program varies somewhat from the listing in Table 10. For
example, MNX is used in the program for both Mn and M , with
•^ 5C
internal program flags distinguishing which variable is being
used at any point in the calculation. Table 11 indicates
equivalencies between variables as designated in the computer
program and as designated in Table 10. The computer program
does not print subscripts, thus producing some obvious equiva-
lencies which are not listed.
A-25
-------
Table 10. Parameters Used in the Parking Emissions Model
Parameter
A
B
C
D
D
Definition
F
F'
G
H
I,-
K'jz
L
Mn
Mx
PCCC-i
PCCOj
Qjz
s
T1
n
Tx
Tz
"z
Vjz
Gross area of parking facility (square feet).
Gross area per parking space (square feet per space).
Percent of the vehicle fleet which is equipped with catalytic converters (percent) .
Standardized travel path length (feet).
Average travel distance for entering vehicles (feet).
Average travel distance for exiting vehicles (feet).
Generalized expression for Dn and Dx.
MOBILE 1 emission rate for vehicles traveling at 5 mph under 100 percent cold start
conditions [PCCO PCCC = 100.0; PCHS = 0.0]; (grams per mile).
MOBILE 1 emission rate for the travel component of vehicle activity in a parking
facility (grams per mile).
Coefficient in the standardized travel path length equation.
Coefficient in the standardized travel path length equation; applicable only to
multiple level parking garages.
Parking facility type code.
Vehicle idle time fraction for MOBILE 1 emission rates.
Cold start idle emission rate derived from Ec (grams per minute).
Hot stabilized idle emission rate from MOBILE 1 (grams per minute).
Weighted hot/cold idle emission rate derived from Ic and Ir (grams per minute).
Idle adjustment factor as used in the computer program (minutes of idling per hour) .
Idle adjustment factor as used in calculator version of the model (grams per vehicle) .
Number of parking levels in an off-street parking facility.
Idle adjustment threshold value for entering vehicles (seconds per vehicle).
Idle adjustment threshold value for exiting vehicles (seconds per vehicle).
Generalized expression for Mn and Mx.
Total number of parking spaces in a facility.
Number of parking spaces in a facility which are used for short-term parking
(duration <1 hour).
Number of parking spaces in a facility which are used for intermediate-term
parking (1 hour <_duration <4 hours)
Number of parking spaces in a facility which are used for long-term parking
(duration ^4 hours) .
Generalized expression for Ps/ P^, and Pj_.
Percent of vehicle activity by catalyst-equipped vehicles which occurs in a cold
start operating mode (percent of vehicle trips). Note that this variable is
treated on a vehicle trip basis, not a VMT basis, when applied to the parking
emissions program.
Percent of vehicle activity by noncatalyst vehicles which occurs in a cold start
operating mode (percent of vehicle trips). Note that this variable is treated on
a vehicle trip basis, not a VMT basis, when applied to the parking emissions
program.
Emissions from vehicle activity in parking facilities during the time period
analyzed (grams). The basic calculation is structured for hourly analyses.
Average vehicle speed in a parking facility (mph).
Coefficient in the equation used to calculate the vehicle idling time accounted
for in MOBILE 1 emission rates (seconds of idling per foot of travel).
MOBILE 1 emission rate idle time for vehicles entering a parking facility (seconds) .
MOBILE 1 emission rate idle time for vehicles exiting a parking facility (seconds).
Generalized expression for Tn and Tx.
Coefficient in average travel distance equation.
Number of vehicle movements during hour being analyzed (vehicles per hour).
Fleet-averaged percent of vehicle movements occurring in a cold start operating
mode (percent of vehicle trips).
Fraction or percent of spaces allocated to a parking duration category in a parking
facility experiencing an entering or exiting vehicle movement during the hour under
analysis; specified separately for each parking duration and movement direction cora-
.bination. The computer program specifies this parameter as a percentage value while
the calculator program specifies this parameter as a decimal fraction.
Subscript j
Subscript z
Subscript used to designate parking duration category:
term, and 1 = long-term.
Subscript used to designate vehicle movement direction-
x = exiting vehicle.
short-term, i = intermediate-
= entering vehicle,
A-26
-------
Table 11. Parameter Designations Used in the Computer Program
Computer Program Designation
of Parameter
BTAB
DNX
EC
FTAB
IDLWTD
IJNX
KJNX
MNX
Q
RP
RUNEM
SP1
STAB
TFAC
TNX
UTAB
VJNX
WJNORX
WJNX
YSNX
Equivalent Designation
from Table
B
Dz
Ic
F
Ir
I •
Kjz
Mz
Qjz
p
Ejz
S
S
T,
Tz
Uz
VJz
wjz
C
Yjz
Note: Additional equivalencies are defined in the computer
program or are obvious (i.e., PS = Ps) .
A-27
-------
The equations used for the parking emissions program
are shown in Table 12. Two formats for calculating Q . are
J ^
shown. The format using K. has been used in the computer
DZ
program. The format using K1 . has been used in a program-
mable calculator version of the model. The programmable
calculator version was used to verify that the computer pro-
gram was functioning properly.
Use of the parking model in Boise involved default values
for most parameters. These are shown in a series of tables
discussed below. Application of this model in other locations
would require different values for some of these parameters.
The computer program installed in Boise is designed to allow
substitution of different parameter values during any in-
dividual program run without deleting the basic default values.
Table 13 presents default values for those parameters
which are a function of facility size and type. Four facility
types were defined for the parking facility inventory and
identified by facility type code (G):
o Home-based trips from the Boise traffic model (con-
verted from person trips to vehicle trips),6=0.
o
On-street parking, G = 1.
o Off-street single level open or covered parking
lots, G = 2.
o Off-street multiple level parking garages, G > 3.
A default hourly temperature curve was established in
consultation with the Idaho Air Quality Bureau (Table 14) .
The MOBILE 1 program does not accept temperatures below 0°F.
The adopted temperature curve is considered representative
of a cold winter day in Boise, but is not based on any statis-
tical analysis of daily temperature records.
The MOBILE 1 program requires the user to input three
parameters defining the operating mode mix for light and
medium duty vehicles in the vehicle fleet being evaluated.
Light and medium duty vehicles are classified into those
with and those without catalytic converters. Three operating
modes are recognized in MOBILE 1: cold start, hot start,
and hot stabilized. In any vehicle fleet, catalyst and non-
catalyst vehicles will exhibit similar frequencies of hot
stabilized operation. Catalyst vehicles, however, will
usually show a higher frequency of cold start and a lower
frequency of hot start operation than noncatalyst vehicles.
A-2 8
-------
Table 12. Equations in the Parking Emissions Model
P = Ps + P± + P
A = (B) (P)
G = L + 1
F1 = 1 + (F) (G
D = F VA~
D = F'VA
Dz = (Uz) (D)
_ (H) (3,600)
(S) (5,280)
TZ = (°z) 3
When G <_ 2
When G > 3
When Yjz specified as decimal fractions
When Yjz specified as percentage values
w._ = (C) (PCCCjz) + (100 - C) (PCCOjz)
]Z
I - EC
-LC -lT
Ijz = (WJZHIC)
Kjz = 0
_ (Mz - TZ)
jz 60
K'jz = 0
K' •„ = (Mz ~ TZ
32 60
= (Ejz) (DZ)
5,280
o. = Fiz) (Dz
-12 5,280
10,000
+ (1 - WJ2) (Ir)
When Mn > Tn or MX < TX
1 z Whrn M * T n~r M "^ T
yvuc:ii ^ An n 1-/J- x X
When Mn i Tn or MX 1 Tx
' (I3Z> When Mn < Tn or Mx > TX
(V3z) + (K1z) (I1z)
J ^ J ^
)+ IK'^' [V^z]
Note: Parameters defined in Table 10.
A-29
-------
Table 13. Parameter Values Defined as a Function of Total
Parking Spaces and/or Parking Facility Type
Parameter
(units)
B
(square feet
per space)
F
(dimension less)
H
(dimension less)
Mn
(seconds per
vehicle)
MX
(seconds per
vehicle)
S
(miles per hour)
(djmcnsionless)
ux
(dimension less)
Facility
Type Code1
(G)
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
G
< 1
= 2
> 3
< 1
"2
> 3
< 1
I 2
< 1
= 2
> 3
= 0
= 1
= 2
> 3
< 1
> 2
< 1
> 2
< 1
> 2
Total
Spaces
(P) Default Parameter Value
NA
P < 100
ior < P < 1,000
p > r, o o r
All
NA
P < 100
ior < p < 1,000
p > r,oor
All
NA
P < 100
ior < P < 1,000
p > r, ooo~
NA
All
All
NA
NA
All
All
NA
P < 100
ior < P < i , ooo
p > r,oor
NA
All
NA
All
B = 0
B = 400
B = 425
B = 450
B = 425
F = 0
F = 0 . S
F = 1.15
F = 1. 3
F = 0.21
H = 0
H = 0.4578
H = 0.4067
H = 0.3299
Mn = 0
Mn = 30
Mn = 45
Mx = 60
MX = 25
Mx = 40
Mx = 60
S = 0
S = 5
S = 7
S = 10
Un = 0
Un = 1.0
Ux = 0
ux = 1.3
Notes:
NA = not applicable
G = 0 For home-based trips.
G = 1 For on-street parking.
G = 2 For single level surface or covered off-street parking lots.
G = L + 1 For off-street multiple level parking garages. L = Number of levels
in the facility.
A-30
-------
Table 14. Default Temperature Pattern for the Boise Area
Clock
Hour
1
2
3
4
5
6
7
8
9
10
11
12
Temperature
(°F)
0
0
0
0
0
0
2
6
8
10
12
14
Clock
Hour
13
14
15
16
17
18
19
20
21
22
23
24
Temperature
(°F)
16
18
20
18
16
14
12
10
8
6
4
2
Notes: Clock hours are designated by the end of the hour.
Thus, hour 8 = 7:00 a.m. to 8:00 a.m. and hour 17 = 4:00 p.m.
to 5:00 p.m.
A-31
-------
The MOBILE 1 program assumes identical hot stabilized
operating mode frequencies for both catalyst and noncatalyst
vehicles. The four cold start and hot start operating mode
frequencies can be determined from any three of the four
values. The MOBILE 1 program uses:
o Noncatalyst vehicle cold start activity (PCCO).
o Catalyst vehicle hot start activity (PCHS).
o Catalyst vehicle cold start activity (PCCC).
For the parking emissions program, these three para-
meters must be defined separately for vehicles entering or
exiting parking spaces for each of the three parking duration
categories. The operating mode of vehicles exiting from
intermediate or long-term spaces is automatically determined
by the time periods used to define these parking durations.
The operating mode for vehicles entering a parking facility
or exiting after a short-term parking duration is not so
easily determined.
The traffic model for Boise was used to determine the
frequency distribution of trip durations. The short average
trip length in Boise results in about 34 percent of all vehicles
completing a trip while still in a cold or hot start mode.
A hand computation of data from the parking facility inventory
indicated that about 35 percent of Boise area trips would
be started after an intermediate term parking duration, thus
producing a similar differential between catalyst and non-
catalyst cold start frequencies. A 20 percentage point dif-
ferential was eventually used because of uncertainty regarding the
hand tabulation of parking inventory data. Table 15 pre-
sents the hourly catalyst and noncatalyst vehicle operating
mode parameters used in the parking emissions model.
While the MOBILE 1 program requires a distinction between
catalyst and noncatalyst vehicle operating modes, the parking
emissions model also requires a calculation of the fleet-
averaged cold start percent. This calculation requires an
estimate of the percent of the overall vehicle fleet which
will be equipped with catalytic converters (Table 16).
Default Vehicle Movement Patterns
Coding of the parking facility data file required several
items of information:
o A map code for reference to the inventory field
maps and notes.
A-32
-------
HR—>
Table 15. Default Operating Mode Parameters (%)
5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
22
23 24
>
OJ
CO
PCCONS
PCCONI
PCCONL
PCHSNS
PCHSNI
PCHSNL
PCCCNS
PCCCNI
PCCCNL
PCCOXS
PCCCXI
PCCOXL
PCHSXS
PCHSXI
PCHSXL
PCCCXS
PCCCXI
PCCCXL
20.
20.
li>.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
20.
20.
15.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
20.
20.
15.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
C.
0.
40.
ICO.
100.
20.
20.
15.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
20.
20.
15.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
20.
20.
1!>.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
20.
20.
lt>.
10.
10.
5.
40.
40.
20.
20.
0.
100.
10.
0.
0.
40.
100.
100.
10.
10.
15.
5.
5.
5.
30.
30.
23.
10.
0.
100.
5.
0.
0.
30.
ICO.
100.
10.
10.
15.
5.
5.
5.
30.
30.
20.
1C.
0.
100.
5.
0.
0.
30.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
U.
'100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
ICO.
100.
15.
15.
10.
10.
5.
10.
35.
35.
li.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
1C.
10.
5.
10.
35.
35.
15.
15.
0.
100.
10.
0.
0.
35.
100.
100.
15.
15.
10.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
0.
40.
ICO.
100.
15.
15.
10.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
0.
40.
100.
100.
15.
15.
10.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
0.
40.
100.
ICO.
15.
15.
1C.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
0.
40.
ICO.
100.
15.
15.
10.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
C.
40.
100.
100.
15.
15.
10.
10.
10.
10.
40.
35.
15.
15.
0.
100.
10.
0.
0.
40.
100.
100.
MOTES:
This table was prepared from a computer printout of the default vehicle operating mode data.
The computer program identifies the data sets using a PCCOZ-; , PCHSz-j , PCCCZj , notation format;
z = entering (n) or exiting (x); j = short-term parking (s), intermediate-term parking (i),
or long-term parking (l).
-------
Table 16. Percent of Boise Vehicle Fleet Expected
to be Equipped With Catalytic Converters
Calendar
Year
1974
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
Default
of C (%
0.
6.
18.
29.
37.
47.
57.
66.
72.
77.
82.
86.
89.
91.
93.
95.
96.
97.
97.
98.
98.
98.
98.
99.
99.
99.
Value
)
0
4
5
8
9
5
6
3
4
8
5
0
0
5
8
4
5
4
9
4
8
9
9
0
0
0
NOTES:
Based on default vehicle fleet mix, Boise
area vehicle age distribution, MOBILE 1
default age-dependent annual mileage dis-
tributions, and MOBILE 1 assumptions for
catalyst equipment rates by vehicle type.
Default vehicle fleet mix:
Light Duty Autos = 71.6%
Light Duty Trucks = 24.6%
Medium Duty Trucks = 2.8%
Heavy Duty Gasoline Trucks = 0.0%
Heavy Duty Diesel Trucks =0.0%
Motorcycles = 1.0%
A-34
-------
o The traffic zone in which the parking facility was
located.
o The highway link designations for any roadways in
the Boise area traffic model which provided direct
access to the parking facility.
o The facility type code.
o An allocation of the total parking spaces in the
facility to the three parking duration categories.
o Identification of an "activity index code" for the
spaces in each parking duration category.
Typical parking duration splits and activity index assign-
ments are indicated in Table 17. While most parking facilities
in the inventory were coded according to the guidance in
Table 17, several exceptions were made to reflect special
conditions. The distribution of total parking spaces among
parking duration categories was completely independent of
activity index code assignment.
The activity index codes were used internally in the
parking emissions model to identify appropriate sets of hourly
vehicle entrance and exit percentages. The general charac-
teristics of the various entrance and exit patterns are out-
lined in Tables 18 through 20. As indicated in these tables,
the computer program was structured to take up to 75 sets
of hourly entrance and exit percentages. In actual appli-
cation, only 49 sets were coded .into the program as default
data. Thus, ample opportunity remains to establish facility-
specific movement patterns for parking facilities of special
concern.
The 49 default activity patterns are identified in
Table 21. The values in this table represent vehicle move-
ments as a percent of parking spaces assigned to the parti-
cular parking duration category. Values in excess of 100
percent are possible for short-term parking. These movement
patterns were developed by Jones & Stokes Associates staff.
They are based largely on individual judgment as to rea-
sonable patterns. Input regarding activity periods for several
land use types was derived from newspaper and telephone book
advertisements. Target values for average occupancy rates
were based on parking survey data and discussions with Ada
Planning Association staff.
A-35
-------
Table 17. Default Guidance for Parking Duration
Category and Parking Activity Index Assignments
General Land Typical Assignment of
Use Groups Parking Duration Categories
(Typical Examples)
Office, school
Financial institution
Industrial, wholesale, warehousing
Building supplies
Medical office
Hospital
Bus station, airport
Grocery, convenience store
Cafe-type restaurant
Restaurant
Fast food
Theater
Shopping center
Motel, bar, auto dealer, furniture,
church, BSU campus
Auto parts, car wash, travel agency,
rental agency, copy shop
Laundry, pest control
Real estate, miscellaneous small
businesses and retail stores
Unrestricted public lots in CBD
On-street parking
Home-based trips
P (%)
s
5
90
0
65
5
10
20
95
25
25
100
0
30
30
85
30
50
0
P (%)
i
20
5
30
30
85
40
10
5
70
70
0
90
60
65
10
65
45
- Variable
- Variable
50
P (%)
75
5
70
5
10
50
70
0
5
5
0
10
10
5
5
5
5
50
Typical Activity
Index Assignments
Y
s
6
9
--
8
7
2
1
4
3
15
5
—
10
14
11
13
12
3
- 3 or 12
""
Y .
i
32
37
31
35
34
28
26
29
29
43
—
42
38
30
39
41
40
29
29
44
Yl
58
59
58
59
58
52
51
—
53
62
—
61
56
54
60
60
60
56
63
NOTES: Parking duration assignments are % of total spaces; P = short-term spaces; P. =
s i
intermediate-term spaces; P = long-term spaces. Y index codes relate to short-term spaces;
J- O
Y. index codes relate to intermediate-term spaces; Y index codes relate to long-term parking,
-------
Table 18. Characteristics of Short-Term Parking Movement Patterns
Short-
Term Activity
Index
-------
Table 19. Characteristics of Intermediate-Term Parking Movement Patterns
Intermediate-
Term Activity
Index
-------
Table 20. Characteristics of Long-Term Parking Movement Patterns
Long-
Term Activity
Index
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
Activity
Period
(Clock Hours)
1-24
1-24
6-22
6-24
6-24
8-22
8-22
8-18
8-19
9-18
10-02
11-01
8-14
Parking Daily
Duration Turnovers
(Hours) Per Space
Mixed; ave. =
12.0 2.15
8.0 2.70
8.0 1.92
8.0 2.00
8.0 2.00
Mixed; ave. =
6.2 1. 85
8.0 1.00
9.0 1.00
8.0 1.00
9.0 1.00
8.0 1.30
8.0 1.00
NA 0.50
Average Peak
Occupancy Occupancy
Factor Factor
31.5-56.5 75-100
90.0 90
90.0 96
84.2 100
84.2 100
76.0 100
53.3 100
81.8 100
66.7 100
90.0 100
61.2 100
53.3 100
NA NA
NOTES:
Index codes 64-75 not yet used.
Clock hour designations (1-24) indicate end of designated hours; for example, hour 8 =
7 a.m.-8 a.m.
Each turnover involves both an entering and an exiting vehicle movement.
The range of occupancy factors for activity pattern 51 reflects the possibility that the
lot is never completely empty.
Activity pattern 63 is applied to home-based trips, not to discrete parking lots.
A-39
-------
Table 21. Default Parking Movement Patterns
HR—> 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 10 19 20 21 22 23
YSNX 1
YSNX 2
YSNX 3
YSNX 4
YSNX 5
YSNX 6
YSNX 7
1
O YSNX 8
YSNX 9
YSNX 10
YSNX 11
YSNX 12
YSNX 13
YSNX 14
YSNX 15
YSNX 16
YSNX 26
20.
30.
35.
45 .
0.
0.
0.
0.
J.
0 .
0.
0.
0.
0.
0.
0.
0.
0.
0.
0 .
0.
0.
0.
0.
0.
0 .
0.
0.
0.
0.
0.
0 .
10.
10.
14.
20.
20.
30.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
10.
10.
a.
8.
20.
20.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
1C.
10.
8.
8.
20.
20.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
10.
10.
8.
8.
20.
20.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
10.
10.
25.
14.
40.
25.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
c.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20.
10.
60.
40.
40.
40.
80.
15.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20.
10.
100.
80.
60 .
45.
120 .
90.
20.
10.
35.
10.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0 .
0.
0.
0.
0.
0.
0 .
3.
0.
0.
3d.
10 .
120.
115.
65.
tO.
100.
125.
30.
20.
50.
55.
10.
0.
40.
5.
80.
30.
25.
10.
30.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
45.
5.
40 .
Ib.
100.
110.
80.
70.
50.
85.
70.
45.
40.
40.
10.
15.
85.
50.
05.
95.
55.
40.
55.
35.
30.
10.
60.
25.
35.
5.
25.
5.
0.
0.
85.
60.
35.
20.
120.
110.
100.
85.
45.
45.
120.
100.
75.
55.
30.
25.
125.
95.
65.
73.
80.
70.
90.
65.
70.
55.
1 10.
85.
80.
45.
45.
30.
0.
0 .
110.
93.
30.
20.
140.
130.
85.
100.
105.
55.
140.
135.
120.
95.
25.
25.
100.
130.
83.
70.
110 .
90.
90.
95.
75.
65.
130 .
120.
110.
90.
70.
50.
90 .
15.
110.
115.
43.
•rO.
160.
150.
60.
75 .
130.
120.
135.
140.
190.
165.
5.
10.
70.
85.
95.
90.
150.
130.
85.
90.
105.
100.
170.
155.
115.
115.
90.
75.
120.
105.
105.
110.
40.
40.
150.
160.
UO.
60.
85.
120.
130.
125.
155.
;?o.
40.
20.
110.
80.
75.
85.
125.
150.
90.
80.
85.
95.
150.
165.
05.
110.
80.
90.
00.
115.
110.
100 .
30.
135.
140.
115.
90.
45.
75.
160.
150.
100.
133.
95.
70.
90.
110.
70.
65.
100.
105.
70.
90.
100.
85.
130.
130.
90.
80.
1 10.
85.
45.
70.
90.
110.
30.
35.
12C.
12'j.
120.
120.
40.
40.
175.
170.
110.
100.
95.
105.
65.
85.
90.
90.
115.
105.
75.
70.
100.
110.
14G.
140.
75.
95.
103..
115.
50.
40.
95.
9 J.
2 5.
40.
150.
130.
140.
125.
55.
40.
160.
165.
90.
105.
25.
65.
5.
50.
80.
80.
105.
1 10.
70.
70.
25.
70.
40.
110.
10.
60.
80.
95.
65.
55.
90.
90.
2C.
40.
ito.
160.
140.
140.
<70.
65.
190.
170.
125.
95.
0.
0.
0.
0.
35.
75.
50.
105.
93.
80.
0.
0.
0.
0.
0.
0.
65.
00.
95.
70.
1 15.
10'J.
25.
35.
135.
150.
120.
135.
9t>.
S5.
145.
1 75.
135.
140.
0.
0.
0.
0.
0.
0.
0.
0.
60.
85.
0.
0.
0.
0.
0.
0.
45.
45.
1 10.
100 .
35.
1 10.
20 .
30.
120.
125.
140.
125.
75.
90 .
115.
130.
115.
125.
0.
0.
C.
0.
0.
0.
0.
0.
70.
65.
0.
0.
0.
0.
0.
0.
75.
65.
95.
110.
90.
«5.
25.
20.
100.
110.
115.
135.
10.
65.
30.
85.
85.
100.
0.
0.
0.
0.
0.
0.
0.
0.
10.
60.
0.
0.
0.
0.
0.
0.
10.
65.
70.
90.
15.
80.
15.
20.
80.
90.
90.
110.
0.
0.
0.
0.
85.
90.
0.
0.
0.
C.
0.
0.
0.
0.
0.
0.
0.
D.
0.
0.
0.
0.
0.
0.
50.
65.
0.
0.
10.
30.
40.
oO.
70.
85.
0.
0.
0.
0.
25.
60.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
35.
45.
0.
0.
10.
30.
40.
40.
50.
65.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
30.
0.
0.
10.
20.
-------
Table 21. Cont'd.
HR—>
10
11
12
13
15
16
17
10
19
20
21
22
23
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
Jp
1
f; YSNX
r~*
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
YSNX
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
5.
5.
5.
10.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
5.
5.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
5.
5.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
5.
5.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
5.
5.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
10.
5.
10.
5.
0.
0.
0,
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
15.
5.
10.
5.
40.
0.
10.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20.
5.
15.
5.
75.
15.
10.
0.
20.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20.
10.
20.
10.
50.
60.
10.
0.
35.
0.
10.
0.
25.
0.
35.
0.
25.
0.
15.
0.
20.
0.
io.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
25.
15.
20.
10.
30.
65.
15.
10.
35.
5.
25.
0.
35.
0.
40.
0.
25.
0.
25.
0.
25.
0.
15.
0.
20.
0.
35.
0.
25.
0.
0.
0.
0.
0.
25.
20.
30.
15.
35.
40.
15.
10.
35.
30.
30.
5.
40.
25.
45.
35.
35.
25.
25.
15.
30.
10.
30.
5.
30.
10.
45.
15.
35.
0.
15.
0.
0.
0.
30.
20.
30.
20.
60.
30.
20.
10.
35.
40.
25.
15.
25.
35.
40.
40.
45.
25.
35.
25.
25.
20,
35.
10.
45.
25.
55.
40.
35.
25.
15.
0.
40.
0.
30.
25.
30.
20.
65.
45.
30.
15.
25.
35.
10.
30.
15.
40.
20.
45.
55.
35.
45.
25.
40.
30.
40.
25.
55.
35.
65.
50.
45.
35.
20.
0.
45.
- o.
30.
25.
30.
30.
35.
75.
30.
15.
35.
30.
30.
25.
45.
25.
50.
40.
40.
45.
30.
35.
45.
25.
30.
30.
55.
50.
65.
60.
30.
35.
20.
15.
20.
15.
35.
30.
30.
30.
35.
45.
30.
20.
35.
30.
15.
20.
40.
15.
40.
20.
35.
55.
25.
45.
25.
35.
25.
40.
35.
60.
45.
70.
25.
45.
15.
15.
5.
50.
35.
30.
30.
30.
40.
30.
30.
30.
2C.
35.
C.
20.
0.
45.
0.
50.
45.
40.
35.
30.
10.
45.
35.
35.
15.
45.
2C.
55.
35.
30.
20.
20.
10.
30.
25.
30.
3C.
30.
45.
40.
30.
30.
0.
30.
0.
30.
0.
40.
0.
40.
0.
35.
C.
25.
0.
35.
30.
30.
0.
30.
0.
40.
0.
25.
35.
20.
25.
15.
20.
35.
30.
30.
65.
40.
30.
30.
0.
40.
0.
0.
0.
0.
0.
0.
0.
45.
0.
35.
0.
20.
40.
20.
0.
0.
0.
0.
0.
35.
35.
15.
40.
0.
20.
35.
25.
30.
65.
55.
30.
30.
C.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
20.
30.
0.
0 .
0.
0.
0.
0.
30.
20.
40.
20.
10.
25.
25.
30.
55.
70.
15.
30.
U *
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
35.
U.
0.
0.
0.
0.
0.
35.
35.
40.
35.
10.
20.
10.
30.
15.
63.
10.
30.
C.
0.
0.
0.
0 .
0.
U.
0.
0.
0.
C .
0.
0.
0.
0.
40.
0.
0.
0.
0.
0.
0.
35.
35.
25.
40.
5.
20.
10.
25.
0.
40.
0.
30.
C.
0.
0.
0.
C.
0.
0.
C.
0.
0.
0.
' 0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
30.
5.
40.
5.
10.
5.
25.
0.
0.
0.
15.
0.
0.
0.
0.
0.
0.
0.
0.
0.
3.
0.
0.
0.
0.
0.
0.
J.
C.
0.
0.
0.
0.
0.
35.
0.
35.
5.
1C.
5.
10.
0.
0.
U.
10.
0.
0.
0.
0.
C.
0.
0.
G.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
35.
0.
15.
-------
Table 21. Cont'd.
HR—>
10
11
12
13
14
15
16
17
18
19
20
21
22
23
YSNX 44
YSNX 45
YSNX 51
YSNX 52
YSNX 53
YSNX 54
YSNX 55
YSNX 56
YSNX 57
YSNX 58
YSNX 59
YSNX 60
YSNX 61
YSNX 62
YSNX 63
0.
0.
0.
0.
5.
5.
90.
90.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
50.
0.
20.
0.
0.
0.
0.
0.
0.
5.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
30.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
5.
5.
0.
0.
0.
0.
0.
0.
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See next page for notes
-------
NOTES:
This table was prepared from a computer printout of the default
activity pattern data. For simplicity in computer programming,
all data sets were designated as "YSNX" data. YSNX codes
1 through 16 represent short-term parking movements. YSNX
codes 26 through 45 represent intermediate-term parking move-
ments. YSNX codes 51 through 63 represent long-term parking
movements.
All values are presented as a percent of the spaces assigned
to the particular parking duration category.
Movement percentages for entering vehicles are listed above
the movement percentages for exiting vehicles.
A-43
-------
Residential Fuel Combustion Emissions
Carbon monoxide emission rates for natural gas and fuel
oil combustion are quite low. Because of this, fuel use
for space heating is seldom included in carbon monoxide
emission inventories. Recent increases in the use of fire-
wood for space heating, particularly with wood-burning stoves,
necessitates consideration of residential fuel combustion
sources. Carbon monoxide emission rates for fireplaces are
more than 82,000 times higher, and those for wood stoves
are almost 600,000 times higher, than emission rates for gas
heaters or furnaces (comparing fuel types on an energy con-
tent basis).
The residential fuel combustion element of the emission
inventories and forecasts evaluated seven fuel combustion
categories: natural gas use for space heating, fuel oil
use for space heating, wood stove use as the main heating
source, wood stove use as a supplemental heating source,
fireplace use as the main heating source, fireplace use as
a supplemental heating source, and natural gas appliance
use (water heaters, stoves, etc.).
Most data on fuel usage patterns were derived from a
recent energy usage survey conducted for the Bonneville Power
Administration (Elrick and Lavidge 1980). This survey included
data for the States of Oregon, Washington, Idaho, and Montana
In applying the data from this survey, no attempt was made
to identify recent shifts in fuel usage patterns or to pre-
dict future shifts. Data for 1980 conditions were applied
to all four inventory and forecast years.
The emission estimates were developed for community
planning areas as defined in the Boise area traffic model
(aggregates of traffic zones). The emission estimates were
not broken down to individual traffic zones. The number
of dwelling units for each community planning area was deter-
mined from the Ada County population and employment forecast
report (APA 1978).
The basic calculation procedure was rather straight-
forward. Average daily fuel use for the November through
February period was estimated for each fuel use category -
This daily fuel use was then partitioned into four 6-hour
time periods. Appropriate emission factors were then applied
to estimate hourly and daily emissions from each fuel use
category. Major assumptions and data sources are identified
in Table 22.
A-44
-------
Table 22. Data and Assumptions Used for Estimating
Carbon Monoxide Emissions From Residential
Fuel Combustion Sources
Topic
Data Assumption
Data Sources
J*
(Jl
Primary Space Heating Type:
Natural Gas
Fuel Oil
Wood Stove
Fireplace
Electrical and Other
Secondary Space Heating Type:
Natural Gas
Fuel Oil
Wood Stove
Fireplace
Gas Appliance Use
Seasonality of Space Heating
Requirements
Annual Natural Gas Usage
for Gas Customers
Partitioning of Annual Natural
Gas Use:
Space Heating
Gas Appliances
Fuel Oil Usage
28% of Dwelling Units
15% of Dwelling Units
9% of Dwelling Units
3% of Dwelling Units
45% of Dwelling Units
2% of Dwelling Units
2% of Dwelling Units
17% of Dwelling Units
25% of Dwelling Units
16% of Dwelling Units
65% of Annual Heating
Degree-Days During
November-February
1,192.5 Therms per
Dwelling Unit
70.3% of Annual Gas Use
29.7% of Annual Gas Use
Equal to Natural Gas
Space Heating Usage
in Terms of BTU
Elrick and Lavidge 1980
Elrick and Lavidge 1980
Elrick and Lavidge 1980
National Oceanic and
Atmospheric Administra-
tion 1971
Elrick and Lavidge 1980
Stanford Research Insti-
tute 1972
Jones & Stokes Associates
Assumption
-------
Table 22. Cont'd.
Topic
Data Assumption
Data Sources
j^
CT\
Firewood Usage for Primary Heating:
Annual
November-February
Firewood Usage for Secondary Heating:
Annual
Novembe r-February
Firewood Characteristics:
Wood Volume Per Cord
Wood Density
BTU Content of Major Fuels:
Natural Gas
Fuel Oil
Firewood
Carbon Monoxide Emission Rates:
Natural Gas Combustion
Fuel Oil Combustion
Wood Stoves
Fireplaces
Primary Space Heating By Time-
of-Day (all Fuels):
Midnight-6 a.m.
6 a.m.-Noon
Noon-6 p.m.
6 p.m.-Midnight
6+ Cords
4.5 Cords
2.0 Cords
1.5 Cords
100 Cubic Feet (78% Wood Volume)
31 Pounds per Cubic Foot
1,000 BTU per 106 Cubic Feet
140,000 BTU per Gallon
7,800 BTU per Pound
20 Pounds per 105 Cubic Feet
5 Pounds per 1,000 Gallons
496 Pounds per cord
68.2 Pounds per Cord
10% of Daily Fuel Use
35% of Daily Fuel Use
20% of Daily Fuel Use
35% of Daily Fuel Use
Jones & Stokes Associates
Calculation From Data in
Elrick and Lavidge 1980
Jones & Stokes Associates
Calculation From Data in
Elrick and Lavidge 1980
Jones & Stokes Associates
Assumptions Based Partly
on Data in Rhude 1976
Gatts et al. 1974
Gatts et al. 1974
DeAngelis et al. 1980
EPA 1976
EPA 1977
Jones & Stokes Associates
Calculations Based on
Data in Cooper 1980
Jones & Stokes Associates
Assumptions
-------
Table 22. Cont'd.
Topic
Data Assumption
Data Sources
Secondary Space Heating by Tiire-
of-Day (all Fuels)
Midnight-6 a.m.
6 a.m.-Noon
Noon-6 p.m.
6 p.m.-Midnight
5% of Daily Fuel Use
15% of Daily Fuel Use
15% of Daily Fuel Use
65% of Daily Fuel Use
Jones & Stokes Associates
Assumptions
Gas Appliance Use by Time-of-
Day
Midnight- 6 a.m.
6 a.m. -Noon
Noon-6 p.m.
6 p.m. -Midnight
5% of Daily Fuel Use
35% of Daily Fuel Use
15% of Daily Fuel Use
45% of Daily Fuel Use
Jones & Stokes Associates
Assumptions Based on Data
in Elrick and Lavidge 1981
NOTES:
1 Therm = 100,000 BTU
BTU = British Thermal Unit
Heating degree days are based on temperature threshold of 65°F
-------
REFERENCES CITED
Ada Planning Association. 1978. Demographic and employment
distribution to the year 2000. Boise. 198 pp.
Benesh, Frank H., and Kenneth W. Wiltsee, Jr. 1979. Carbon
monoxide emission inventory and analysis of nonattainment in
Ada County, Idaho: final report. GCA Corporation, Bedford,
MA. Prepared for U.S. Environmental Protection Agency,
Idaho Operations Office. 40 pp.
COMSIS Corporation. 1978. Boise urban area transportation plan-
ning models. Prepared for Idaho Transportation Dept., Boise.
Cooper, John A. 1980. Environmental impact of residential wood
combustion emissions and its implications. J. Air Pollut.
Control Assoc. 30 (8):855-861.
De Angelis, D. G., D. S. Ruffin, and R. B. Reznik. 1980. Pre-
liminary characterization of emissions from wood-fired resi-
dential combustion equipment. U.S. Environmental Protection
Agency, Research Triangle Park, N.C. EPA-600/7-80-040.
145 pp.
Elrick and Lavidge, Inc. 1980. The Pacific Northwest residential
energy survey, vol. 1: executive summary. Bonneville Power
Administration, Portland, OR. 81 pp.
Gatts, Robert R., Robert G. Massey, and John C. Robertson. 1974.
Energy conservation program guide for industry and commerce.
National Bureau of Standards handbook no. 115. U.S. Government
Printing Office, Washington, D.C.
Nelson, Randy. January 7, 1981. Transportation networks for trans-
portation years. Memorandum from Ada Planning Association to
Bob Sculley, Jones & Stokes Associates, Inc. 3 pp.
Rhude, Maurice J. 1976. Wood design and construction. Section 11
in Frederick S. Merritt, ed., Standard handbook for civil
engineers. 2nd ed. McGraw-Hill, New York.
Smith, Malcolm, and Tom Aldrich. 1977. Development of revised
light-duty vehicle emission-average speed relationships. Pre-
pared for U.S. Environmental Protection Agency. 254 pp.
A-4 8
-------
Stanford Research Institute. 1972. Patterns of energy construc-
tion in the United States. Prepared for U.S. Office of
Science and Technology. U.S. Government Printing Office, Wash-
ington, D.C. 156 pp. + appendices.
U.S. Environmental Protection Agency. 1974. Natural gas combus-
tion. Section 1.4 in Compilation of air pollutant emission
factors, 2nd ed;, supple. 3. Prepared by Office of Air Quality
Planning and Standards, Research Triangle Park, N.C.
.. 1977. Fuel oil combustion. Section 1.3 in Compila-
tion of air pollutant emission factors, 2nd. ed., supple. 7.
Prepared by Office of Air Quality Planning and Standards,
Research Triangle Park, N.C.
. 1978a. Guidelines for air quality maintenance plan-
ning and analysis, vol. 9: evaluating indirect sources. rev.
ed. Prepared by Office of Air Quality Planning and Standards,
Research Triangle Park, N.C. EPA-450/4-78-001. 165 pp. + appen-
dices.
1978b. User's guide to MOBILE 1: Mobile source
emissions model. Prepared by Office of Air, Noise, and Radiation,
Washington, D.C. EPA1400/9-78-007. 133 pp.
U.S. National Oceanic and Atmospheric Administration. 1971. Cli-
mate of Idaho. Climatography of the United States No. 60-10.
Prepared by Environmental Data Service, Silver Spring, MD.
A-49
-------
APPENDIX B
Fiscal Overview on Ada County
Prepared for:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
By:
Gruen Gruen + Associates
564 Howard Street
San Francisco, CA 94105
July 1980
-------
TABLE OF CONTENTS
Page
APPENDIX B - INTRODUCTION B-l
Fiscal Overview B-l
I. Local Public Services and Finance in
Ada County B-2
A. Service Provision B-2
B. Organization of Local Government
Finance B-2
II. Fiscal Prospects: The Short-Run Picture B-6
A. Declining Revenues B-6
B. Uncertain Direction of Future Imple-
mentation of Initiative No. 1 B-7
C. The Current Fiscal Response B-8
D. Hidden Costs B-9
E. Need for Action B-9
III. Fiscal Prospects - The Long-Run Picture B-10
A. Stabilizing Revenues B-10
B. Administrative Remedies B-ll
C. More Comprehensive Financial Planning B-12
D. Going Private B-12
E. Land Use Planning Responses B-13
IV. Area Summary B-14
A. City of Boise B-14
B. City of Eagle B-15
C. County of Ada B-15
D. The Southwest Area B-16
E. Conclusion B-17
B-i
-------
LIST OF TABLES
Table Page
B-l Property Taxes As Proportion of Local Budget
In Selected Ada County Jurisdiction B-3
B-2 Revenue Sources In Boise And Eagle B-4
B-iii
-------
Appendix B
INTRODUCTION
Fiscal Overview
Between 1975 and 2000, Ada County is expected to more
than double its population, growing from 139,400 to 293,000
residents. This growth, which a regional wastewater facility
would in part accommodate, will require significant expendi-
tures of both public and private funds in order to provide the
services needed by present and new residents, among which
schools, roads, public safety, water supply, storm drainage
and wastewater services may be mentioned. One of the many
underlying issues in considering regional growth relates to
the ability of local public service agencies to pay for that
growth.
This issue of fiscal capability has been addressed by
Gruen Gruen + Associates through interviews with staff and
elected officials of local general purpose governments supple-
mented by a review of relevant documents. Of particular con-
cern is the effect of 1978 state referendum limiting property
taxes to one percent of market value. At the present time,
the fact that the Idaho State Legislature has not yet enacted
a detailed program to implement the initiative both beclouds
the long-run future and compounds the short-run fiscal diffi-
culties of local governments in Ada County. However, a descrip-
tion of current fiscal conditions and likely future adjustments
provides a useful basis for a qualitative assessment of the
ability of local service entities to continue to finance their
future activities and to provide local residents with an ac-
ceptable level of public services.
This fiscal review begins with a discussion of local ser-
vice delivery and finance in Ada County. The second and
third sections discuss short- and long-run fiscal prospects
for general purpose governments in Ada County. A concluding
section provides an overview and commentary for each of the
four major areas addressed by the wastewater facilities plan:
Ada County, the City of Boise, the City of Eagle and the south-
west area.
B-l
-------
I. Local Public Services and Finance in Ada County
A. Service Provision
There is a wide variation in the specific pattern of re-
sponsibility for service provision in the greater Boise area.
First, certain services are provided by the public in some
areas and by private entities or individuals themselves in
other areas. For example, while urban populations of Boise
are provided sewer service by the public, in less densely
settled portions of Ada County on-site wastewater systems are
frequently installed and maintained by individual property
owners.
Second, certain services are provided by local general
purpose government in some areas (particularly in Boise)_ and
by special purpose districts in others. In the City of Eagle,
virtually everything except general government is provided
by independent agencies: sewer, water, schools, fire.
Throughout the county/ public education is provided by school
districts rather than by general purpose government.
These variations suggest the difficulty of generalizing
about either service provision or cost/revenue issues. De-
pending on where a residence or business is located, it may
receive a different package of public services from a dif-
ferent set of service providers, and these differences result
in further differences in the quality/quantity of service pro-
vided and its cost. Altogether, there are 50 different public
agencies in Ada County with service responsibilities and taxing
authority.
Finally, it is often the case that the chief city in a
region provides certain services not provided by other public
agencies in the region, and this is true in Ada County. Boise
provides an Art Gallery, the Boise Zoo, certain activities of
the Boise Recreation Department, and the Boise bus system which
are supported by Boise taxes but used by many people living
outside Boise. A 1977 study found that the proportion of users
of the first three of these services who live in Ada County
outside Boise is about 27 percent, the same percentage as the
total non-Boise population in the county. These out-of-city
users do not pay taxes for what they evidently consider "re-
gional" services (Groebner and Merz, December 1977).
B. Organization of Local Government Finance
Certain of the features of local government finance in
Idaho are common to the various entities empowered to provide
services and to tax, and these similarities arise from state
B-2
-------
legislation regulating the operations of local governments..
Some of the most important aspects of the finance system are
described below.
1. Balanced budgets. The State of Idaho requires that the
budget for any given year must be. in balance. Neither can a
deficit be incurred nor can a surplus be accumulated. As a
practical matter, this means that local agencies typically
understate their revenue anticipation so as to ensure that
they will not find themselves with a revenue shortfall at the
close of the fiscal year.
An exception to the rule is Boise, which operates on a
tax anticipation basis rather than a cash basis, a practice
predating the state's 1977 balanced budget requirement.
2. Revenue sources. Property taxes have long been the
mainstay of local government finance in Idaho. Table B-l
shows the extent to which local governments in Ada County
have depended on property taxes in the past. This dependence
has been declining throughout the 1970's, and the one-percent
initiative seems likely further to reduce local agencies' re-
liance on the property tax.
Table B-l. PROPERTY TAXES AS PROPORTION OF
LOCAL BUDGET IN SELECTED ADA COUNTY JURISDICTIONS
1971
1976
1979-80
*1972.
Source: Boise
Ada
County ,
42.1%
33.4%
43.7%
City, 1979-80.
Ada
County
Highway
District
39.3%*
37.5%
31.6%
Boise City Budget.
City of
Boise
36.2%
19.01%
15.09%
Boise
School
District
51.4%
48.6%
43.6%
Other taxes may be imposed at local option if authorized
by state legislative action. Examples of such taxes now in
effect are taxes on liquor-by-the-drink in McCall and Sun Val-
ley (both major visitor areas). The sales tax, which is an
important local tax in some other states, is a trivial element
in the local tax structure in Idaho, although a local sales
tax could be tacked onto the state's three-percent rate as a
local option (again, state approval would be a prerequisite)
Other current revenue sources include federal and state
grants and revenue sharing; fees, fines, reimbursements for
B-3
-------
services, licenses and permits; interest; rents; and miscel-
laneous other sources. Table B-2 sets forth the distribution
of revenues in the Cities of Boise and Eagle in their 1979-80
budgets.
Table B-2. REVENUE SOURCES IN BOISE AND EAGLE
Source
City of Boise
Annual Proportion
Revenue from That
(Thousands) Source
City of Eagle
2nd Quarter Proportion
Revenue from That
(Thousands) Source
General/
Property Taxes
State Shared
Sales Tax and
Liquor Tax
Federal and
State Grants
Revenue Sharing
Fees, Fines and
Re i:nbu r s cme n ts
for Services
Licenses and
Permits
Interest Income
Rents
All Other
TOTAL
10,100.0
1,300.0
27,000.0
1,700.0
12,700.0
800.0
400.0
2,000.0
10,800.0
66,700.0
15.1%
1.9%
40.5%
2.5%
19.0%
1.2%
0.6%
3.0%
16.2%
100.0%
18.3
3.6
0.2
3.2
6.6
0.5
0.9
33.3
55.0%
10.8%
0.6%
9.6%
19. 8%
1.5%
2.7%
100.0%
Source: Boise City, 1979-80. Boise City Budget, p. xvii. Eagle City, 1980.
Statement of Revenue for the Quarter Ended March 31, 1980. Note that
Eagle's revenue statement is for the second quarter of the fiscal year
while Boise's is an estimate for the entire fiscal year. Comparable
data for the county are not available.
3. Administrative structure for property tax collection.
Each local taxing entity sets its own tax rate.Because the
jurisdictional boundaries of these entities differ, neighboring
properties can have different composite tax rates if their pro-
perties lie in different taxing districts. Each possible com-
bination of taxing districts is called a tax code area and in
Ada County there are over 200 different tax code areas, which
is to say areas within which the combination of service-providing
B-4
-------
entities (and therefore the composite tax rate) is different
from all other areas of the county.
While the one-percent initiative and related state legis-
lation limited the basic property tax take to one percent of
market value, it did not revise the administrative structure,
and that has made the impact of the initiative more severe.
Since state law provides that each taxing entity must have
a uniform rate of property taxation throughout its jurisdic-
tion, each tax code area within that jurisdiction shows the
same tax rate for that particular service. But since in no
tax code area may the composite rate exceed the one percent
of market value level, the tax code area in which the maximum
tax burden is imposed is the highest tax code area in the
county, and the rates in all tax code areas with service en-
tities overlapping the one percent area must reduce the var-
ious service entities' tax rates in order to maintain the
same rates throughout each service jurisdiction.
Thus, the one percent upper limit is not achievable
throughout the county: most tax code areas must have lower
rates in order to observe the requirement of rate consistency
within jurisdictions, and as a result the reduction in pro-
perty tax revenues effected by the one-percent initiative has
been considerable. A recent study (Business Economics, Inc.,
1979) estimates Boise City's reduction in property tax revenues
as 55.36 percent, and every taxing entity whose jurisdiction
overlaps the City of Boise (for example, Ada County and the
Boise School District) has had to absorb the same reduction.
4. Market values and property taxes. Property taxes
generally are calculated as the rate (determined by the taxing
entity) times the value of the property, which in most parts
of the United States is the assessed valuation as determined
by the county assessor's office.
It is typically the case that state law mandates or guides
the manner in which local officials value property. Idaho law
requires that by 1982 assessed valuations must be a uniform 20
percent of fair market value. In the past, there has been con-
siderable variation in local valuation practice, and a more
typical ratio of assessed valuation to market value was prob-
ably 10 percent. While certain local governments (such as
Boise) moved rapidly in response to the legislation to bring
their valuations up to the 20 percent level, others moved
more slowly, and when Initiative Petition No. 1 passed, pro-
perty in those jurisdictions was still undervalued. These
governments have bee.n able to revalue property to the 20 per-
cent level since the initiative passed, and this has cushioned
somewhat the immediate impact of the initiative in those juris-
dictions .
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Under the provisions of the one-percent initiative, pro-
perty may be revalued but the revaluation is limited to an in-
crease of two percent per year from a 1978 base. Over time,
assuming recent inflation rates persist, the property tax
base will represent an ever decreasing portion of total mar-
ket values as a result of this limitation. Only new improve-
ments and properties that change hands are excluded from this
limitation.
5. Bonding. It is common practice throughout the nation
for the capital facilities requirements of public services to
be financed through bonds. Such government bonds may be either
general obligation bonds (repaid from the jurisdictions' gen-
eral revenues, such as property taxes) or revenue bonds (re-
paid through charges imposed for the specific service provided
by the facility financed via bonds).
These kinds of public finance instruments have not been
used as extensively in Idaho as they have in more urban states
and as a result none of the local jurisdictions - Boise, Eagle
or Ada County - has reached the limit of its bonding capacity
(ten percent of assessed valuation). This finance tool must
be mentioned, however, because it represents one of several
possible ways of financing public improvements independently
of restrictions on property taxes (bonded indebtedness is
specifically excluded from the one-percent property tax limi-
tation) . On the other hand, financing via bonds is not par-
ticularly popular in Idaho, where there is a strong tradition
of pay-as-you-go financing. School bonds have failed to re-
ceive the required two-thirds approval in the past, and every
bond measure - such as the $7,000,000 airport bond measure ap-
proved by Boise voters in November 1979 - must be fully ex-
plained to and understood by the voters in order to obtain ap-
proval .
II. Fiscal Prospects: The Short Run Picture
In the short run, all three local general purpose govern-
ments - Boise, Eagle and Ada County - are experiencing similar
conditions: a sharp decline in revenue relative to three years
ago, and consequently pressure to accommodate this change by
altering the revenue structure and/or the volume of service
delivered.
A. Declining Revenues
Initiative 1, as the Idaho legislature has implemented
it on an interim basis, has frozen local budgets for a three-
year period at their 1978 levels. In anticipation of the
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passage of the initiative, some local governments had already
begun to trim budgets prior to June 1978, and it is those gov-
ernments (Boise is one) that have been hit hardest by the
across-the-board budget freeze.
With budgets frozen during an inflationary period, the
actual fiscal impact is more severe than simply a frozen bud-
get may suggest. The costs of providing government services,
.like the costs of other goods and services in the economy,
continue to rise with inflation. Just as households have to
spend more to maintain their historic standard of living, gov-
ernments have to spend more to maintain their historic levels
of service delivery. That simply cannot be done on a frozen
budget. The result, as described by an Eagle councilman, is
that by mid-1980, his city's ability to spend was about 50 per-
cent of what it had been three years before.
Property taxes are not the only revenues that have de-
clined. With the rising mortgage interest rates of the last
two years, the downturn in housing construction and the current
recession, development-related fees have also declined, which
has hit Ada County particularly hard since much of the revenue
supporting the Growth Management Department derives from fees,
Fee le.vels have been increased, but total collections still
appear to be falling short of the level normally needed to
support past levels of planning and land development regula-
tion activities.
B. Uncertain Direction of Future Implementation
of Initiative No. 1
The passage of the initiative did not specify the means
of implementation, and the State of Idaho (lacking the kind
of surplus that California had when the similar Proposition
13 was passed in that state) has taken only interim measures
to date to remedy some of the problems posed by the property
tax limitation. An important step has been the earmarking of
certain revenues from the three percent state sales tax to
relieve the fiscal plight of the school districts.
However, further measures appear in doubt. The apportion-
ment question (how to allocate tax rates or total tax revenues
among taxing districts) poses a particularly difficult problem
for whoever decides to address it, whether at the state level
or at the county level. And with this question unresolved,
local agencies, particularly those in the faster-growth areas,
are left not only poorer but without official guidance on
their future fiscal organization. On the other hand, their
straitened circumstances have required immediate action.
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C. The Current Fiscal Response
Cities and the county are taking a number of steps to
bring their costs into line with their current revenue streams.
Among these are the following:
1. Annexation policies. The City of Boise is looking
much harder at annexations before proceeding with them, this
caution stemming from the city's limited ability to extend
services to new areas. While Eagle is still considering an-
nexations (the Middlebrook annexation in particular), the de-
velopment process is to be structured in phases to permit the
city flexibility to adjust later phases in the event circum-
stances (such as service capacities) alter in the meantime.
Ada County, for its part, is giving increasing weight to the
desirability of ensuring that new urban scale development take
place within municipal contexts rather than in unincorporated
areas - a step which should reduce the county's service re-
sponsibilities to such areas over time.
2. Cost reductions. The most common cost reduction
strategies, which all three agencies are pursuing to some ex-
tent, are (1) reducing personnel costs, (2) eliminating capital
facilities expenditures to those financed wholly by federal
funds and (3) reducing maintenance expenditures. Boise of-
fered several specific examples. The city's permanent staff
has dropped from 1,100 to about 700. (This drop has been
accomplished both by attrition and by a layoff of 258 staff
members, including 22 firemen.) Certain services are being
spread more thinly or discontinued altogether. Some examples:
grass cutting in public green spaces is being reduced, the
smaller contribution to the Humane Society is increasing the
dog population of the city (and concomitantly reduced animal
enforcement is reducing dog license revenues) ,• the diets of the
zoo animals are being reviewed to determine what cost savings
are possible, and the weed control ordinance has been repealed.
Not all of these reduced services" meet public approval, but the
city feels it must make these and comparable changes to keep
costs and revenues balanced. The representatives of each of
the three governments generally echo the view that the voters
seem to want cuts only in those services which do not affect
them - but as every service benefits somebody, no cuts can be
completely painless.
The maintenance reduction is particularly worrisome to
public finance personnel, who feel that this strategy simply
builds up major public facility expenditure needs sooner than
would be required if ongoing maintenance could be kept at
its past levels.
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3. Reexamination of local government's public service
role. The irony of Initiative No. 1 is that it cuts back on
the resources of that level of government which had been
thought to be most readily responsive to the electorate, while
it does nothing to reduce the spending or the obtrusiveness
of the state and federal governments. But local governments
must respond to the mandate to limit their roles, and one
likely target for reduction is services not mandated (or re-
imbursed) by federal or state requirements. Emergency medical
services provides a good, example in Ada County. Public trans-
portation, too, is a service Boise provides (partly under
pressure from the federal government stemming from air quality
considerations) which is presently not mandated and is heavily
subsidized.
D. Hidden Costs
One of the concerns local governments express is that of
being able to cope with sudden expenses, or with long-term
costs of public improvements not now being undertaken. The
recent problems faced by many Pacific Northwest communities in
cleaning up in the aftermath of Mount St. Helens ash fallout
provides an excellent example of public costs that cannot
readily be foreseen but must be dealt with on a crisis basis.
An example of the second kind of problem is surface water
drainage, a need not being addressed on a coordinated basis
in Ada County at present. Costs of coping with this problem,
which is particularly acute in the area to the southwest of
the City of Boise, may well exceed the $20,000,000 level. Such
costs of "new" services will be difficult for existing govern-
ments to absorb under current strapped fiscal conditions.
E. Need for Action
Public officials of all three jurisdictions - Boise,
Eagle and Ada County - agree on the importance of responding
to the property tax limitation initiative in a manner that
will permit restoration of adequate levels of public service.
Although the approaches which at present seem most appealing
differ among jurisdictions, there is agreement on the desir-
ability of coping responsibly with future needs so as to
allow a resumption of regional growth along the lines desired
in each community.
Local governments are particularly concerned about aorne
of the adverse impacts that may result from Initiative No. 1.
Among these are the loss to public agencies of good staff
people who may resign if they feel long term opportunities
are better elsewhere. Another is the concern that a decline
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in public service levels could prove a disincentive to firms
to locate in the region. In particular, high technology firms
that consider a number of regions when locating a new plant
are known to be particularly sensitive to the quality of
the educational system locally, as their highly-trained pro-
fessional and technical people insist upon this feature in
deciding whether to accept assignment to new locations. So
if the Boise area is to continue to move in the direction of di-
versifying and strengthening its economic base by adding clean
industry of this kind, there is a limit to the extent of cost-
cutting in public services that can be accommodated consistent
with economic development objectives.
These kinds of concerns have motivated local government
to look beyond the current problems of coping with the Ini-
tiative One aftermath to future questions of efficiency and
productivity in service delivery and long run solutions to
revenue problems.
III. Fiscal Prospects: The Long Run Picture
Although public service finance in the Boise region
faces definite current difficulties, most observers from
all three jurisdictions see some positive outcomes of Initia-
tive One and point to a number of future actions to relieve
the current crisis and put local general purpose governments
on a firmer footing.
A. Stabilizing Revenues
Although, unless there is a 2/3 override of the property
tax limitation, it appears that public revenues from that
source will provide a decreasing proportion of- local govern-
ment revenues as time goes on, other sources of revenue have
been identified and will eventually be tapped. Among those
specifically mentioned by local agencies are general obliga-
tion bonds (exempt from the provisions of the initiative),
special purpose bonds such as for industrial development and
housing finance (require state enabling legislation but are
common in other states), local option taxes and state payments
in lieu of taxes. The latter revenue source would be of par-
ticular assistance to the City of Boise, which hosts the state
government and has within its municipal boundaries a considerable
amount of state property not subject to property tax though
eligible for city services.
All jurisdictions are looking to imposition of user char-
ges (authorized by state legislation) and imposition or increases
in fees wherever possible. Ada County in particular has been
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considering growth management fees in line with a study the
Ada Planning Association Board commissioned with funds from
the Pacific Northwest. Regional Commission. Although the
methodology, of that study has been criticized by some readers,
there is general agreement that under current fiscal conditions
some residential development probably does not "pay its own
way"; the main arguments lie in (1) whether a growth manage-
ment fee - a fee to cover the capital costs of future public
services - is the proper response to this situation, and (2)
how to allocate capital costs among various types of land use.
Using other states' experience as an indicator, certain fees
(such as for school site dedication and park dedication) have
been upheld by the courts and are in widespread use, and the
principle is certainly readily applicable to such other ser-
vices as fire and police. Even its advocates recognize, how-
ever, that this approach covers only capital facilities, leav-
ing open the question of the ongoing financing of operating
costs. And if payment of such fees is required to precede
issuance of permits, the magnitude of the charges may well be
sufficient to deter some development.
B. Administrative Remedies
1. Solving the apportionment problem. A problem dis-
cus sed~~earTTerr~Ti~~EEat~ofimposing the maximum one percent pro-
perty tax rate in all tax code areas, which is not possible
currently due to discontiguity among taxing districts. This
problem could be solved (as California has solved it) by im-
posing the one percent tax on a county-wide basis arid then
apportioning the revenues among taxing districts. Thus far,
the legislature has not proposed this approach, and county
commissioners (who are familiar with county budgets but are
certainly much less familiar with the problems of the special
districts) have not been willing to take aggressive action
in this direction. Although the situation appears currently
to be at an impasse, most observers feel that a solution to
the problem will eventually be hammered out - if only because,
in the interim, tax revenues are going to fall far short of
the permitted one percent level in most areas of most counties.
So there is a powerful impetus for solving this problem.
2. District consolidation. The apportionment problem
has called public attention to the number of special purpose
taxing districts in Ada County, and the general feeling is
that the number (around 50) is excessive. Economies of opera-
tion may well be possible if certain districts are consolidated.
Such consolidation can take place either on a functional basis
(i.e., several fire districts merging into one) or on a geo-
graphic basis (fire, open space, wastewater service to a given
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area provided by a single district - just as city governments
generally operate). Both of these kinds of consolidation are
being widely studied in California for the same reasons (econ-
omy and increased efficiency) they are being proposed in Idaho.
The chief impediment seems to be that the special districts,
with elected boards, do offer valuable opportunities to area
residents for public involvement which would be reduced if
the number of such districts were cut back. But the benefits
of the approach are such that movement in this direction is
a realistic expectation.
In the meantime, an interim measure could be the dis-
couragement of new district formation. This appears to be
the point of view of Ada County at present. The Middlebrook
controversy has drawn attention to the potential problems that
may arise when a city is empowered to approve an annexation
and subsequent development project the principal services to
which are the responsibility of other entities.
C . More Comprehensive Financial Planning
The current fiscal crisis has drawn attention to the
need for more thorough-going and long run analysis of public
finance requirements, which has spurred Boise in particular
to begin to look at long term financial planning as an import-
ant aspect of municipal finance. This kind of planning is
seen as integrated with long term development planning in a
coordinated package to make public actions more efficient and
consistent. Boise has also been working with a group of
private-sector financial experts to improve the operation of
financial planning and reporting systems, and is establishing
data processing techniques to improve the capability, speed and
accuracy of financial reporting systems.
D. Going Private
As mentioned earlier, there are a number of utilities or
services that can be (and frequently are) performed by private
entities rather than by public agencies. These include water
(whicii in rural Ada County is generally provided by on-site
wells or private services) and solid waste disposal (where
housenolders may be individually responsible, for hauling their
own refuse to a dump site or for contracting with a private
firm to provide this service - the City of Boise recently made
mandatory household trash collection by a private service).
If the costs of providing a public service system appeared
prohibitive, it might be possible in some cases simply to put
the responsibility for providing that service on the individual
householder. There are a number of kinds of arrangements for
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accomplishing this approach. Often, homeowners' ass6ciations
in new subdivisions can take responsibility for such functions
as landscape maintenance and weed control, pest control (func-
tioning as mosquito abatement districts), surface water drain-
age, street and street lighting maintenance, and so forth.
This approach relieves the public sector of financial respon-
sibilities, and gives the appearance of making new development
less costly to the public.
However, the approach doesn't make development less ex-
pensive for the new home buyer, who is paying the homeowners'
association for the same services he might otherwise have been
paying some public entity for, and the resident may actually
end up paying more to the extent that public agencies can fi-
nance long term improvements in a less costly manner (i.e.,
through bonds) than private developers can. Furthermore, there
has been concern expressed in other states where this approach
is more widespread that these "private" responsibilities would
devolve upon the public in any case should a homeowners' asso-
ciation go into default.
Less structured private systems, such as on-site wells
and on-site septic systems, are often possible where densities
are low and these approaches, too, initially look less costly
from the point of view of the public treasury. But cost savings
of this kind may well be offset by cost increases in other
functions: more miles of roads are needed to serve dispersed
development, more travel by school buses to bring children to
schools, and so forth. Thus, private service provision must
be thoroughly analyzed before it can be concluded, on balance,
to be cheaper than the public alternative.
E. Land Use Planning Responses
1. Tying new development to existing infrastructure. The
high cost of new service extensions has called attention to the
advantages of utilizing existing infrastructure to accommodate
new development. Such an approach reduces the commitment of
capital required to serve new growth while it offers the ad-
vantage of reducing average costs of those already served by
an existing system that is operating at less than capacity.
2. Contiguous development. A second way in which fiscal
constraints can alter land use planning is by pointing up the
advantages of contiguous development. If new development abuts
existing development, costs of service extension are generally
less than they would be if the newly-developing area were sepa-
rated from the urban boundary by vacant or undeveloped land.
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3. Cautious approach to annexation. Recognizing the
lower level of financial resources available, cities may well
resist annexation proposals that in the past would have been
almost routinely approved. The property tax limitation initia-
tive, in Idaho as in California, has tended to change the out-
look toward annexation of both annexors and annexees. Before
the initiatives, unincorporated areas often resisted annexa-
tion because their tax rates would rise; now, with tax rates
more or less equalized between incorporated and unincorporated
areas, this source of resistance has been greatly reduced or
altogether eliminated. On the other hand, cities which in pre-
initiative days considered annexations desirable because of
additions to the property tax base have found that benefit
much reduced, and are often legitimately concerned that the
increase in property tax revenues resulting from annexation
will not compensate for additions to service costs. It is for
these reasons that Boise is currently discouraging annexation
proposals.
4. Development phasing. The fiscal constraints local
governments are now experiencing also make them more cautious
about giving approvals to long-term development projects,
because the service and fiscal conditions that apply when such
projects begin may no longer obtain by the time of their com-
pletion. Furthermore, there are clear advantages in maintaining
ongoing approval authority of large projects in the event of
delays in completion, changes in ownership or management, or
other conditions that might result in an alteration in the
developer's intentions or objectives.
An example of the kind of project expected to be subject
to approval by phases is Middlebrook. Phased approvals have
been used by the City of Eagle on earlier proj-ects, and this
approach can be expected to be used more extensively by Idaho
jurisdictions generally as long as the current fiscal crisis
lasts.
IV. Area Summary
A. City of Boise
Boise has felt the impact of Initiative One more severely
than other jurisdictions because it operates on an accrual
basis and because its property had already been revalued up
to near the state-mandated limit at the time the initiative
passed. That the reduction in revenues has caused severe short
term problems is unquestioned. However, the long term outlook
is not bleak. Certain additional sources of revenues seem
likely to be tapped in the future and Boise will likely
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continue to receive more state and federal funds, as a propor-
tion of its budget, than do the other general purpose govern-
ments reviewed.
The fiscal crunch has underlined the practicality of some
of Boise's planning policies, particularly the preference for
infill development in the southeast and (to a lesser extent)
the northwest. This growth corridor is the most easily ser-
viced by municipal agencies and in many cases the infrastruc-
ture to support new development in these areas is already in
place. Growth elsewhere - and particularly to the west and
southwest - will be more closely scrutinized in the future,
with fewer annexations, preference given to contiguous develop-
ment, and a close tie-in between long term physical development
planning and capital improvement planning to assure efficiency
and minimum public cost.
B. City of Eagle
Eagle is still a comparatively small town, with a 1980
population probably in the range of 3,000 (a substantial in-
crease over the population at 1971 incorporation of less than
400). The area of impact of the town, which is the city's
planning area as delineated in the Ada County Comprehensive
Plan, is expected to see steady growth over the next decades
bringing the future population of the community to over 10,000
(exclusive of the Middlebrook development) as indicated in
APA Board-adopted subarea population projections. Local pro-
jections range from 15,000 (Eagle's sewer consultant) to 20,000
and upward, and generally incorporate the Middlebrook develop-
ment proposal.
The growth of the community is not expected to abate much
as a result of current fiscal problems because the current scale
of operation of the City of Eagle is quite modest and no immediate
change in this characteristic is expected. One of the city's
sources of appeal for new residents is reportedly its small
town character and the direct accessibility of its government.
While this can be expected eventually to change as the local
population increases, the present structure of urban service
provision - most services are provided by special districts
charging user fees - insulates the city somewhat from the more
severe effect of Initiative One noted elsewhere. The concern
about Eagle's growth often expressed in the region relates
more to regional planning questions than directly to fiscal
capacity, although the special districts providing services
to parts of Eagle City may encounter their own fiscal problems
in extending services, and that has not been explored in the
course of this qualitative review.
C. County of Ada
Ada County revenues have fallen short of earlier expecta-
tions because of Initiative One and lower construction activity
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(which has reduced fee revenues). The county has responded
by trimming staff and services where possible. If the current
crisis is prolonged, a reduction in non-mandated services is
a reasonable expectation.
Looking beyond the immediate future, it appears that the
county, like the City of Boise, will be affected by fiscal
constraints in terms of its future development policies. This
has already been happening to some extent, but the revenue re-
duction has given this direction greater impetus. There will
be a reluctance to permit discontiguous development, a closer
evaluation of the public costs of new development, and more
assiduous observation of a policy to encourage new development
to annex to existing municipalities and to obtain city - rather
than special district - services. In general terms, the philo-
sophy of the county will increasingly be to support municipal
growth while unincorporated lands would be retained in rural
uses. The implications of this approach in terms of the spa-
tial distribution of growth are plain. Whether such a policy
would also serve to inhibit growth is less clear.
D. The Southwest Area
The area lying to the south and west of Boise has been
seen by many as a desirable growth area, and much development
has taken place there in the last 10 years. Of the approxi-
mately 16 square miles in this area, about half is already
subdivided, and the current population is about 14,000.
The fiscal crisis has been one factor prompting the re-
cent reassessment of the magnitude of future growth in this
area. The cost of providing urban services to the dispersed
development pattern that currently exists in the area has
proven to be higher than was hoped, creating resistance to
construction of public wastewater facilities. And the prospect
of dealing with the costs of other kinds of service needs -
such as surface water drainage - may make people more cautious
in he future about settling in that area. Finally, accessi-
bility to downtown Boise - still the main employment and ser-
vice center in the region - is inferior from the Southwest
Area as compared to the urban corridor along the Boise River,
leading some to suggest that rising energy costs will also
serve to limit the growth of this area.
In addition to economic factors, there also are lifestyle
preference factors involved in attitudes about urban services
and growth in the Southwest Area. Many of the properties are
small acreages on which owners keep animals and cultivate a
more rural life style than would be possible, say, in the
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southeastern part of the City of Boise. These residents may
object to establishment of capital intensive public services
(such as a regional wastewater system) not only because of the
high cost but also because they feel it is inimical to the kind
of residential environment they want to retain. The view of
the Ada Planning Association's Board of Directors on this mat-
ter seems to be that local residents should not be forced to
pay for a system they don't want, but that planning and capi-
tal facilities decisions should not foreclose the possibility
of future densification to a more urban development pattern.
Because this area is in the unincorporated county and lies
within a number of special service districts, it would be diffi-
cult to characterize its fiscal prospects, but it does seem
clear that the combination of lower property tax revenues and
an increasing awareness of the cost of urban services may re-
sult in less growth than had been anticipated, at least over
the next decade.
E. Conclusions
Although this investigation has been qualitative and no
forecast of long-term public costs or revenues has been under-
taken, it seems clear from the review completed that current
fiscal problems are causing a reassessment of growth and plan-
ning policies in many of Ada County's jurisdictions.
While local officials believe the resources will be
available to accommodate future growth, that growth is probably
more likely to be concentrated in or adjacent to existing ur-
ban communities than might have been expected a few years ago,
with this pattern of concentration helping to assure efficiency
in urban service delivery and minimum average cost. The cur-
rent recession in the economy, which has been evidenced in part
by the downturn in new construction, has given local communities
some breathing time to adjust their planning, development and
fiscal policies in response to the new fiscal constraints they
face.
An unanswered question is whether the mechanisms for guiding
growth are strong and consistent enough to achieve the stated
policies of Ada County and the City of Boise. If not, the
southwest area may continue to experience more extensive large-
lot rural development, relying on individual or private ser-
vices, than local public agencies want. Elsewhere, development
of outlying areas is limited under county zoning to essentially
agricultural use (1 unit per 80 acres in agricultural use areas
and 1 unit per 160 acres in rangeland areas) except that
smaller parcels are allowed where there is no water available
for irrigation (1 unit per 40 acres) or in approved subdivisions.
How many undeveloped parcels exist in the latter is not known,
but no new subdivisions in the rural areas have been authorized
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since 1977. Given this zoning pattern it does not presently
appear likely that more restrictive development policies with-
in and at the edges of urban areas would cause much rural
spillover development outside the southwest area.
However, a more substantial issue is the resilience of
the regional economy itself if housing prices continue to
rise in response to scarcity, and housing price, type and
locational availability pose disincentives to people consider-
ing moving into the region. If events take that direction,
there will be more pressure on local public agencies to facili-
tate development through both fiscal and planning policies.
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BIBLIOGRAPHY
Persons Consulted
Ayers, W. Floyd. Director of Finance and Administrative
Management, City of Boise. June 9, and June 26, 1980.
Bermeosolo, Gary. Chairman, Ada County Board of County Com-
missioners. June 10, 1980.
Gerber, Sheldon. Planner, Ada Planning Association. June 9
and June 10, 1980.
Krasen, Orval. Councilman, City of Eagle. June 9, 1980.
Ralston, Paul L. Executive Director, Greater Boise Chamber
of Commerce. June 10, 1980.
Reference Documents
Ada County. Ada County Budget. 1979-80.
Ada County. Annual Financial Statement for the Fiscal Year
Ending September 30, 1979. December 1979.
Boise Chamber of Commerce. "Growth Management Labeled as
Fee-bull" in Boise Business Today, Vol. 33, No. 6. July 1980,
Boise Chamber of Commerce, Blue Ribbon Committee on 1%. Memo-
randum on the 1% Initiative. Undated.
f
Boise Chamber of Commerce, Task Force on Growth Management
Fees. Report. May 1980.
Business Economics, Inc. An Analysis of Growth Management
Fees in Ada County, Idaho (summary report and complete text).
Commissioned by Ada Planning Association Board and Office
of the Governor, Division of Budget, Policy Planning and
Coordination, State of Idaho. December 1976.
Eagle City. Statements of Revenues. January 1, 1977 through
March 31, 1980.
Groebner, Dr. David F. and Dr. C. M. Merz. Non-resident Use
of Boise City Services. December 1977.
Merz, Dr. C. M. and Dr. David F. Groebner. Study of Alterna-
tives to the Property Tax for the City of Boise. December
1976.
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APPENDIX C
ISSUE PAPER
Population Projections for
Ada County EIS Analysis
Prepared By:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
With the Assistance Of:
Gruen Gruen + Associates
564 Howard Street
San Francisco, CA 94105
February 1980
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TABLE OF CONTENTS
Section 1 - INTRODUCTION C-l
Approach and Contents of Issue Paper C-l
Intent of EIS Analysis of Population Alternatives C-2
EPA Policy on Population Projections for
Facilities Planning C-2
Historical Context C-3
Section 2 - DESCRIPTION AND ASSESSMENT OF DED
PROJECTIONS C-5
Methods and Results C-5
County Total C-5
Disaggregations to Planning Areas C-6
Assessment of DED Projections C-ll
Assessment of Methods C-ll
Comparison with Recent Trends C-14
Section 3 - POTENTIAL ALTERNATIVE POPULATION
PROJECTIONS FOR EIS ANALYSIS C-l7
-ff.
Boise Planning Area C-17
Southwest Planning Area C-17
Eagle Planning Area C-21
Countywide Alternatives C-21
Section 4 - ISSUES C-23
Do the Middlebrook and Southwest Area Population
Increases Represent New Growth? C-23
How Will Grant Eligibility Be Determined? C-24
Are There Other Proposed Major Land Developments
Which Could Increase Population Projections? C-24
APPENDIX A C-25
C-l
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Table
2-1
2-2
2-3
2-4
3-1
3-2
LIST OF TABLES
Summary of DWR/BSU Series 2 Population
and Employment Projections
Summary of DED Planning Area Population
Projections
Year 2000 Ada County Employment
Comparison of Projected 1975-1980 Population
Growth with 1978-1979 Subdivision Plat Data
List of Potential Population Alternatives
for EIS Analysis
Boise Planning Area Population Projections
Pac
C-7
C-8
C-9
C-15
C-18
C-20
Figure
2-1
2-2
2-3
3-1
LIST OF FIGURES
Boise Metropolitan Area
Southwest Area
Eagle Planning Area and Community Plan
Boise Metropolitan Service Area and
Planning Areas
Page
C-10
C-12
C-13
C-19
C-iii
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Section 1
INTRODUCTION
Approach and Contents of Issue Paper
As part of the Environmental Impact Statement (EIS)
being prepared by Jones & Stokes Associates, Inc., for three
Ada County wastewater projects, the secondary impacts of
the population growth accommodated by these projects will
be analyzed. Task D-2 of the EIS scope of work requires
the preparation of population projection alternatives for
EIS analysis; these alternatives are intended to reflect
population alternatives being proposed in the three waste-
water management plans.
This issue paper has been prepared to establish the
context for selection of population alternatives for EIS
analysis. The paper consists of four sections and one
appendix. The remainder of this INTRODUCTION (Section 1)
describes the intent of the EIS analysis of population alter-
natives; describes the U. S. Environmental Protection Agency's
(EPA) policy on population projections for facilities planning;
and describes the historical context of population projections
being proposed for Ada County wastewater planning. Section 2
consists of a description and assessment of the Ada Planning
Association (APA) 1978 baseline population and employment
projections, which were intended to serve as the baseline
for the EIS analysis of alternatives. Section 3 presents
a broad range of population alternatives which could be analyzed
in the EIS; it is expected that several, but not all, of
these alternatives will be selected for EIS analysis. The
last section, Section 4, outlines several issues affecting
the choice of population alternatives for further analysis.
The appendix to this issue paper, prepared by Gruen Gruen +
Associates (economic consultants for the Ada County EIS),
presents an economic evaluation of increases in population
over the 1978 APA projection proposed for two planning
areas, the Southwest Area and the Eagle planning area.
C-l
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Intent of EIS Analysis of Population Alternatives
The analysis of population alternatives in the EIS is
intended to serve two major purposes. First, population
alternatives for each of the wastewater plans need comparison
to assure that they are consistent with one another. If
this were not done, then theoretically population projections
could be determined which seem reasonable for each area,
but which, when added, produce an unrealistically high pro-
jection for the county as a whole. EPA's concern in this
regard is that capacity in excess of need is not funded.
Second, population alternatives for each wastewater
plan, and for the county as a whole, need to be assessed
in order to determine secondary impacts and mitigation
measures. A major issue in the Ada County EIS is the secondary
impacts of the growth accommodated by the wastewater plans
and measures to mitigate significant adverse impacts. Assess-
ment of the impacts of alternative population projections
in the EIS will lead to a greater public review of plan impacts
and to an informed decision-making process.
EPA Policy on Population Projections
for Facilities Planning
EPA's policy for population projections to be used for
facilities planning is set forth in Appendix A of the agency's
cost-effectiveness analysis guidelines (40 CFR 35, Supplement
E). The policy requires wastewater facilities plans to use
population projections developed by states or appearing in
approved 208 plans, provided that state projections do not
exceed Bureau of Economic Analysis (BEA) projections by more
than 5 percent and that 208 plan projections do not exceed
state projections by more than 10 percent. New BEA projections
are currently being developed under increased control by
the federal Office of Management and Budget (OMB) and with
greater participation of states and 208 planning agencies.
However, new BEA projections for substate districts are
not expected until at least 1981.
In Idaho, the state baseline population projection
for facilities planning was developed by the Bureau of Water
Quality (BWQ) and approved by EPA on January 10, 1980; this
state baseline projection was developed by extrapolating
C-2
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1970-1976 growth rates for the years 1980, 1990 and 2000.
The state baseline indicates a year 2000 population of 268,622
for Ada County. On January 15, 1980, the BWQ requested a
revision to the Ada County projection, raising it to 289,000
as a result of APA work; this request is currently under
review by EPA.
Historical Context
Several events in the 1978-1980 period are of particular
importance for the development of population alternatives
for EIS analysis.
Adoption of 1978 Demographic and Employment Distributions,
Population and Employment Projections by APA
In August 1978, the APA adopted the report "Demographic
and Employment Distributions (DED) to year 2000" (DED pro-
jections) . This report presents population and employment
projections, in 5-year intervals, for Ada County and for
smaller statistical areas. The year 2000 projection for
Ada County population was 289,000.
The DED projections were adopted as the population pro-
jection baseline for all APA regional planning programs,
including 208 areawide waste treatment management planning.
Therefore, at the same time the EIS scope of work was prepared,
the DED projections were intended to serve as the baseline
for EIS analysis as well. The DED projections are described
and assessed in Section 2 of this paper.
Amendment of DED Projections Adding 7,010 to Southwest Area
In August 1979, the APA Board authorized increasing
the year 2000 population of the Southwest Area from 22,380
(in the DED projection) to 29,390. This action also increased
the county total from 289,010 to 296,010. The change was
based upon a more detailed evaluation of subdivision lots
than was done for the DED projections.
C-3
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Proposed Middlebrook Development
In spring 1979, a major development was proposed on
520 acres south of the City of Eagle. The Ada County Zoning
Department estimates that this development would generate
2,000-7,000 jobs and 700-800 dwelling units. About half
of the development would be devoted to a "technological park",
which would be a significant employment generator.
Population implications of this development have not
been fully assessed by local agencies. However, a working
figure of 16,000 for the year 2000 population of the Eagle
planning area has been advanced; this represents an increase
of 5,745 people over the DED projection of 10,255. Ultimate
induced population from the Middlebrook development would
be considerably higher than the 5,745 estimate.
On December 4, 1979, a letter from EPA to the Eagle
Water and Sewer District indicated no agency objection to
planning for a population higher than 10,265, such as 16,000,
but indicated that design and construction of facilities
funded by state and EPA grants must conform to the 10,255
figure unless the 208 plan (DED projections) is formally
amended. APA has expressed disagreement with this EPA decision,
EPA Approval of Idaho Baseline Projection
On January 10, 1980, EPA approved the Idaho baseline
population projection, developed by the BWQ, which indicates
a year 2000 Ada County population of 268,622.
BWQ Revision to Baseline Projection
On January 15, 1980, the BWQ requested revision of the
year 2000 Ada County population projection to 289,000. This
revision is based on the APA DED projections.
C-4
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Section 2
DESCRIPTION AND ASSESSMENT OF
DED PROJECTIONS
Because the DED projections were intended to serve as
the baseline for EIS analysis, and because they continue
to serve as baselines for wastewater facilities planning
for areas other than the Southwest Area, this section reviews
the methods and results o'f the DED projections. The section
concludes with a brief assessment of the methods and results
of the projections.
Methods and Results
County Total
Methods. The DED year 2000 population projection of
289,000 for Ada County was based on the DWR/BSU 1976 popu-
lation and employment forecast (also referrred to as Idaho
Population and Employment Forecasting Model [IPEF] 73). It
should be noted that the 1976 DWR/BSU projections were re-
vised in 1978, and that the "Series 2" projection for year
2000 Ada County population is 293,581. The Series 2 pro-
jections are based on an extended employment data base
covering 16 years of data (1961-1976) instead of the original
6 years (1967-1972).
The DWR/BSU projections were prepared by using the IPEF
model, which consists of two separate forecasts: 1) a popula-
tion forecast prepared by using the cohort survival method
and 2) an employment projection which is then converted to
a labor demand projection. The model compares the population
forecast to the labor demand projection, and adjusts the
population forecast so that a balance is achieved.
C-5
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Results. A summary of the Series 2 population and
employment projections is presented in Table 2-1. Popu-
lation is projected to more than double from 136,140 in 1975
to 293,580 in the year 2000. Total employment shows a similar
increase, from 67,520 jobs in 1975 to 149,010 jobs in the
year 2000.
As mentioned, the Series 2 year 2000 population pro-
jection of 293,580 is somewhat higher that the original DWR/BSU
year 2000 projection of 289,000. The difference between
the two amounts is 4,580 people.
Disaggregations to Planning Areas
Methods. The DED projections were disaggregated to
subcounty planning areas and to smaller traffic analysis
zones by APA. Only the planning area disaggregations are
reviewed here. The DED report (page 5) indicates that the
disaggregations to planning areas were performed using the
following general methods:
"... the most recent planning goals and policies for
each area (metro planning areas, small cities, subsections
of planning areas, etc.), were considered. Approved and
expected developments, County/Metro Land Use Plan and recom-
mendations, historical trends, service planning areas as
related to capacities, economic housing type trends, and
growth patterns in each of these smaller units were the basis
for determining the future population and employment dis-
tribution for the County."
Results. The results of the DED planning area projections
are summarized in Tables 2-2 (population) and 2-3 (employment)*
Further detail regarding the projections for the Boise Metro
Area (excluding the Southwest Area), the Southwest Area,
and Eagle are provided below.
Boise Metro Area (Excluding Southwest). Separate pro-
jections were prepared for southeast Boise, north river west
bench, and central bench (see Figure 2-1 for a map of these
areas). These projections take into account factors such
as recommended densities and other policies in the Boise Metro
Plan, the Garden City Plan, and the City Center Plan;
available vacant land in each planning area; and development
constraints such as the floodplains, power lines, canals and
benches.
*The DED projections were based on "Series 1" DWR/BSU county
totals, which are slightly lower than the Series 2 projections
presented in Table 1.
C-6
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Table 2-1. Summary of DWR/BSU Series 2
Population and Employment Projections
Total population
Total employment*
Labor force**
Total school en-
rollment
Nursery
Kindergarten
Elementary
High school
College
i
"^ Household heads
1
112
57
55
33
1
18
9
4
35
970
,230
,080
,180
,860
300
,330
,730
,080
,420
,830
1975
136,140
67,520
68,070
39,410
390
2,030
19,690
11,360
5,920
43,860
1980
166
82
83
46
2
22
12
7
54
,340
,800
,400
,270
500
,690
,990
,500
,570
,010
1985
192
95
95
52
3
27
12
8
63
,380
,490
,920
,620
580
,210
,720
,570
,510
,130
1990
222,
110,
111,
61,
3,
32,
15,
9,
73,
810
500
060
810
650
740
830
380
200
630
1995
254,800
127,710
128,320
70,520
720
4,130
37,090
18,220
10,340
' 84,420
2000
293,580
149,010
149,640
80,440
830
4,640
41,640
21,180
12,130
97,730
* Employment base year = 1972
**Labor force base year = 1970; labor force is dependent upon unemployment rate and the
average number of jobs held by each worker
SOURCE: Idaho Department of Water Resources/Boise State University, 1978. Population
and Employment Forecast -- State of Idaho, Series 2.
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Table 2-2. Summary of DED Planning Area
Population Projections
O
I
CD
Southeast
North River
City Center
North End
Northwest
Foothills
Warm Springs
West Bench*
Central Bench
Southwest
Total Metro
Meridian
Eagle
Kuna
Rural Area**
Total Nonmetro
Total Ada County
1
11
35
2
17
5
6
3
28
36
9
120
6
2
1
8
18
139
975
,425
,650
,940
,180
,310
,725
,495
,700
,105
,080
,960
,349
,720
,308
,063
,440
,400
Additional
4
2
34
1
1
1
11
1
3
9
8
2
6
7
3
3
8
7
5
4
36
14
9
,100
,300
,715
930
,145
,431
,079
,415
,250
,300
,365
,801
,505
,517
,412
,235
,600
2000
53
69
6
18
24
15
5
45
43
22
234
25
10
6
12
54
289
,525
,950
,655
,110
,455
, 156
,574
,115
,355
,380
,325
,150
,225
, 825
,475
,675
,000
Year 2000
(% of Total)
18
24
2
6
8
5
1
15
15
7
81
8
3
2
4
18
100
.5
.2
.3
.3
.5
.2
.9
.6
.0
.7
. 1
.7
.5
.4
.3
.9
.0
* Includes Garden City
**Includes Star
SOURCE: Ada Planning Association, 1978. Demographic and Employment Distribution
to the Year 2000: Ada County, Idaho.
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Table 2-3. Year 2000 Ada County Employment
Retail
Pers. Ser.
Southeast
North River*
City Center
North End
Northwest
Foothills
Warm Springs
West Bench
Central Bench
Southwest
Total Metro
i Meridian
^ Eagle
Kuna
Rural Area
Total Nonmetro
Total
Ada County
3,469
18,426
14,841
901
1,516
915
253
5,069
4,644
1,700
33,308
2,386
581
405
422
3,794
37,102
Office
Finance
6,548
24,382
21,290
546
372
540
1,634
1,738
4,475
287
37,430
455
158
97
121
831
38,261
Ind. , Const.
Whoise., Transp.
3,319
3,666
1,480
506
965
365
350
5,286
4,543
14,693
31,507
1,531
510
335
1,770
4,146
35,653
Gov't.
223
15,512
11,159
1,116
670
1,451
1,116
1,228
1,428
2,277
20,668
737
290
179
445
1,651
22,319
Educ.
2,847
2,069
684
393
547
300
145
992
949
487
7,344
566
222
154
274
1,206
8,550
Social
Recreation
359
1,615
1,126
131
177
94
87
298
307
161
2,740
150
59
33
62
304
3,044
Total
16,765
65,670
50,580
3,593
4,247
3,665
3,585
14,611
16,346
19,605
132,997
5,815
1,820
1,203
3,094
11,932
144,929
*North River = City Center + North End + Northwest + Foothills + Warm Springs.
SOURCE: Ada Planning Association, 1978. Population and Employment Distribution to the Year 2000: Ada County, Idaho.
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Boise
Metropolitan
Figure 2-1
Area
PLANNING AREAS
1. Southeast /
2. North River-
3. West Bench
4. Central Bench \
5. Southwest
Northwest
North End
City Center
Warm Springs
Foothills
11111II111111 1111 u 1111111111111111111111 • «i r.
"*,
* ^
%0->?/ '"'•
V
SOURCE: Ada Planning Association, 1978. Population and
Employment Distribution to Year 2000: Ada County,
Idaho. C-10
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Southwest Area. The Southwest Area population projection
of 22,380 was based on several factors (see Figure 2-2 for
map of the Southwest Area). These include a Boise Metro
plan recommendation that development incompatible with the
airport influence zone not be allowed and an assumption that
the Southwest Area would remain low density and not reach
the density of 4-5 dwelling units per acre thought to be
needed to support a central water and sewer system. The
assumption that the area would remain low density was in
response to recommendations of the Boise Metro plan to channel
growth to southeast and northwest Boise, and also in response
to expected transportation constraints and high costs of
a central sewer system.
Eagle. The year 2000 projection of 10,255 for the Eagle
planning area was based on the 1978 Eagle comprehensive plan.
This plan supports an overall policy of limited growth and
maintenance of Eagle's semirural community character. Figure
2-3 shows the Eagle planning area and community plan.
Assessment of PEP Projections
Assessment of Methods
The IPEF model used to prepare the DWR/BSU projections
is an excellent, flexible tool which can be used to observe
the sensitivity of population to changes in demographic or
economic variables. The model avoids the error of assuming
that past growth rates will continue into the future when
economic circumstances have changed. It should be recognized,
however, that the DWR/BSU projections of county population
do not recognize local land use policies or local environ-
mental constraints to growth.
The methods used by APA are representative of those
used by other councils of governments attempting to dis-
aggregate a regional'control total to subcounty planning
areas. The DED report contains a particularly detailed docu-
mentation of methods and assumptions used to prepare the dis-
aggregations. In general, the methods used to prepare the
APA disaggregations have two potential drawbacks. Most
importantly, they appear in some cases to assume that "build-
out" (ultimate development) will occur at the year 2000;
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Figure 2-2. Southwest Area
n
i
SOUTHWEST COMMUNITY
STUDY AREA
STUDY AREA BOUNDRY
SOURCE: Ada Planning Association, 1979. Existing Conditions and Characteristics of
Study Area.
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Figure 2-3. Eagle Planning Area and Community Plan
Central City 5 du/ac
Rural low density 3 du/ac
Central Business District
Industrial
'-•V, vCcT-\ Greenways
FLOOD PLAIN
Floodway
Floodway Fringe
"•" 1992 Sewer and Water Planning Limits
—*mr; 1982 Sewer and Water Planning Limits
184 Traffic Zones
SOURCE:
Ada Planning Association, 1978. Population and
Employment Distribution to Year 2000: Ada County
Idaho. '
C-13
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the time phasing of achieving build-out is given insufficient
attention. Secondly, the disaggregations are based on a
"composite" of regional, county, local, and in some cases
special district plans and policies, as well as recent trends
and approved developments; conflicts among these policies,
trends, and approved developments are likely, but these con-
flicts are generally not identified in the DED report.
Comparison with Recent Trends
Total Ada County Population. The DWR/BSU Series 2 Ada
County population projection for 1980 is 166,347. (The first
DWR/BSU projection, upon which the DED projection is based,
indicated a 1980 population of 165,211.) Although a firm
estimate of 1980 population will not be possible until the
1980 census data become available, recent rough estimates
indicates the likelihood of a 1980 Ada County population of
about 165,000-166,000. Ada Data, Inc., in its 1979 Boise
Real Estate Research Report, estimated a 1978 population
of 157,400. APA staff (pers. comm.) has estimated a mid-
1979 population of about 160,000. These rough estimates
are fairly consistent with a 1980 projection of 165,000-
166,000, assuming the county continues to grow at an average
annual increase of 6,040 people during the 1975-1980 interval
as projected in the DWR/BSU projections.
Subdivision Trends by Planning Area. Table 2-4 compares
1975-1980 population growth projected in the DED projections
with 1978-1979 subdivision plat data compiled by APA; this
comparison allows a qualitative assessment of the extent
to which subdivision activity has been consistent with pro-
jected population growth for each planning area.
The APA subdivision plat data fluctuate significantly
from one 6-month reporting period to the next. Nevertheless,
some overall conclusions are possible. From the data in
Table 2-4, it is apparent that:
o Subdivision platting activity has been greater in
1978-1979 than would have been expected from the
1975-1980 DED population projection for west bench
and Meridian.
o Subdivision platting activity has been less in 1978-
1979 than would have been expected from the 1975-
1980 DED population projection for north river,
southeast, and Eagle.
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Table 2-4.
Comparison of Projected 1975-1980 Population Growth
With 1978-1979 Subdivision Plat Data
o
i
H-
01
% Of Total Platted Lots
Planning Area
North River1
Northwest
West Bench
Central Bench
Southeast
Southwest2
Eagle
Meridian
Kuna
Rural Area
19753
Population
30
5
28
36
11
9
2
6
1
8
,340
,310
,700
,105
,425
,080
,720
,349
,308
,063
19803
Increase, 3
Population
33
7
32
37
17
12
3
8
1
9
,822
,853
,640
,716
,319
,071
,800
,920
,983
,087
1975
3
2
3
1
5
2
1
2
1
-1980
,482
,543
,940
,611
,894
,991
,080
,571
675
,024
% of3
Increase
13.
9.
15.
6.
22.
11.
4.
10.
2.
4.
5
9
3
2
8
6
2
0
6
0
7/78-
12/78
6.5
0.4
25.9
7.2
16.1
16.3
3.7
19.3
0.0
4.5
1/79-
5/79
9.4
0.2
25.1
8.7
26.3
4.4
0.0
20.7
1.6
3.6
6/79-
12/79
14.4
22.3
26.5
7.5
10.5
0.2
0.0
16.6
1.9
0.2
Total
139,400
165,211
25,811
100.I5
99.95 100.0
99.95
1North River except for northwest subarea.
2 Includes airport planning area.
3SOURCE: Ada Planning Association, 1978. Demographic and Employment Distribution to Year
.2000: Ada County, Idaho.
4SOURCE: Ada Planning Association. Ada County Recorded Subdivision Reports.
5Total does not add due to rounding.
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o Subdivision platting activity in 1978-1979 has been
about what could have been expected from 1975-1980
BED population projection for central bench, Kuna,
and the rural area.
o No clear comparison is possible for northwest and
southwest.
Overall, the data in Table 2-4 indicate a general
consistency between the 1975-1980 projected population
growth and 1978-1979 subdivision platting activity. This
comparison must be qualified because it does not consider
the build-out of subdivision plats approved prior to 1978.
If pre-1978 plat data differ greatly from the 1978-1979 data,
then subdivision trends and projected population growth
over the 1975-1980 period may not agree as closely as in-
dicated in Table 2-4.
C-16
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Section 3
POTENTIAL ALTERNATIVE POPULATION
PROJECTIONS FOR EIS ANALYSIS
This section presents various alternative population
projections that could be used for EIS analysis. Separate
sets of alternatives are presented for the Boise planning
area, for the Southwest Area, for the Eagle planning area,
and for Ada County as a whole. These alternatives are listed
in Table 3-1. It is expected that some, but not all, of
these alternatives will be selected for analysis in the EIS.
Boise Planning Area
It is only necessary to consider one population alter-
native for the Boise planning area. This is the projection
developed by CH2M Hill in its Planning and Design Criteria
Technical Memorandum. For the Boise planning area (defined
as the Boise metropolitan area minus the Southwest Area,
see Figure 3-1) initial population projections for total
and sewered population are shown in Table 3-2.
This projection is intended by CH2M Hill to be based
on the DED projection. However, a discrepancy exists between
the two projections. For the year 2000, the DED projection
for the Boise planning area would be 211,945, derived from
subtracting the Southwest Area projection (22,380) from the
total metro area projection (234,325). This DED projection
is 6,815 lower than the CH2M Hill projection for the same
area. CH2M Hill (pers. comm.) has indicated that the initial
year 2000 projection of 218,760 was in error, and that the
Boise planning area projection should be approximately 212,000
Southwest Planning Area
APA 1979 Baseline
APA's 1979 baseline projection for the Southwest Area
in the year 2000 is 29,390. Two density options have been
C-17
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Table 3-1. List of Potential Population
Alternatives for EIS Analysis
Boise Planning Area Alternatives
CH2M Hill projection*
Southwest Planning Area Alternatives
APA baseline (year 2000 = 29,390)
High density (4 dwelling units/acre)
Low density (2 dwelling units/acre)
DED projection (year 2000 = 22,380)
Eagle Planning Area Alternatives
DED projection (year 2000 = 10,255)
"Middlebrook" projection (year 2000 = 16,000)**
Countywide Alternatives
APA baseline (year 2000 = 296,010)
Original distribution
Redistribute 5,745** from remainder of county to Eagle
"Middlebrook" projection (year 2000 = 301,765**)
DED projection (year 2000 = 289,000)
Original distribution
Redistribute 7,010 from remainder of county to Southwest
Area
Redistribute 12,755** from remainder of county to
Southwest Area and Eagle
*Apparent discrepancy with DED projection, needs resolution
**Needs refinement
C-18
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figure 3-1. Boise Metropolitan Service Area and Planning Areas
o
i
.
PLANNING
AREA 5 i
«c»i, BOISE j • -t . .
TREATMENT PLANT , ' X^
J L •
PLANNIN<3
PLANNING NV \ • SUB AREA 4a
"^-• —
SOURCE: CH2M Hill, 1979. Planning and Design Criteria Technical Memorandum.
-------
Table 3-2. Boise Planning Area Population Projections1
Planning
Area
1*
Subarea 1A
2
3
4*
Subarea 4A
5
Totals
n
i
NJ
O
1975 Base
31,940
6,295
31,015
40
9,905
3,860
39,460
112,350
1979
Total
35,010
8,135
31,410
40
17,000
8,000
42,385
125,845
Sewered
15,245
0
28,700
0
12,000
6,000
40,490
96,435
1985
Total
46,090
9,080
33,060
40
28,355
12,670
46,385
153,930
Sewered
30,580
4,600
31,125
0
25,105
11,170
44,995
131,805
1990
Total
54,145
10,665
33,200
45
40,785
19,665
49,225
177,400
Sewered
40,205
7,155
31,910
45
39,285
18,665
48,240
159,685
1995
Total
61,950
12,205
34,000
50
53,310
27,910
52,435
201,745
Sewered
53,625
10,200
33,355
50
52,310
27,410
51,910
191,250
2000
Total
66,790
13,155
35,685
55
60,660
34,735
55,570
218,760
Sewered
66,790
13,155
35,685
55
60,660
34,735
55,570
218,760
*Includes subarea populations.
lrltotal population data source "Demographic and Employment Distribution to Year 2000, Ada County, Idaho", Boise Metro
areawide policies; prepared by the Ada Planning Association, August 1978.
Sewered population in 1979 based on "Boise Metropolitan Area Master Sewer Plan", map prepared by the Boise City
Department of Public Vforks, December 1978, and actual sewer district connections.
SOURCE: CH2M Hill, 1979. Planning and Design Criteria Technical Memorandum.
-------
developed to meet this projection, two dwelling units per acre
and four dwelling units per acre. On December 13, the APA board
adopted the high density alternative, which will be analyzed
in the EIS. The low density alternative, although it has
been rejected, could additionally be analyzed in the EIS.
PEP Projection
APA's initial year 2000 projection for the Southwest
Area in the BED report was 22,380. Although this projection
has since been revised upward, it is still the adopted 208
plan projection, and could be analyzed as an alternative
in the EIS.
Eagle Planning Area
PEP Projection
The BED projection for Eagle for the year 2000 is 10,255.
This alternative, which represents the adopted 208 plan
projection, could be analyzed in the EIS.
i:Middlebrook" Alternative
A working estimate of 16,000 for the year 2000 projection
has been made for Eagle if the Middlebrook development is
approved. This number would need to be refined further before
being analyzed in the EIS. A major question is-the extent
to which population grpwth induced by the Middlebrook project
would locate within the Eagle planning area, as compared
to other locations in Ada County or in Canyon County-
Countywide Alternatives
APA Baseline
The revised Ada County baseline population projection
for the year 2000 is 296,010; this incorporates the 7,010
added to the Southwest Area projection. This alternative
should be analyzed in the EIS using the original BEB distribution,
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In addition, a new alternative could be analyzed which re-
distributes 5,745 people from the remainder of the county
to Eagle. This alternative and any others requiring county-
wide distributions would need to be developed by APA staff.
"Middlebrook" Projection
The additional 5,745 people resulting from approval
of the Middlebrook project could be added to the APA base-
line total, creating a new county total of 301,755 for the
year 2000.
PEP Projection
APA' s initial projection for Ada County was 289,000.
Although this projection has since been revised upward, it
is still the adopted 208 plan projection, and could be
analyzed as an alternative in the EIS. Three distributional
alternatives could be analyzed to meet the 289,000 projection
the original DED distribution; redistribution of 7,010 from
the remainder of the county to the Southwest Area; and re-
distribution of 12,755 from the remainder of the county to
the Southwest Area and to Eagle.
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Section 4
ISSUES
Several issues are associated with the choice of popu-
lation projections for analysis in the EIS. These include
the following:
o Do the Middlebrook and Southwest Area population
increases represent "new" growth?
o How will grant eligibility be determined?
o Are there other proposed major land developments
which could affect population projections?
Do the Middlebrook and Southwest Area Population
Increases Represent New Growth Beyond Prior Forecasts?
Gruen Gruen + Associates has analyzed the relationship
between the population increases proposed for Middlebrook
and the Southwest Area. Their full analysis appears in
Appendix A and is summarized here.
With regard to Middlebrook employment, it is clear that
the IPEF forecast of employment (upon which the DED pro-
jection is based) did not account for up to 7,500 jobs in
the electronics industry in Ada County by the year 2000;
it also did not account for jobs associated with the Hewlett
Packard plant under construction. Between 1975 and 2000,
the IPEF forecast of total job growth in the "other manu-
facturing" section (which includes the electronics industry)
is only 3,815.
This does not necessarily mean that the overall IPEF
forecast is too low, since low estimates in one sector can
be offset by overestimates in another. Gruen Gruen + Associates
believe that it is not possible to determine whether Middlebrook
will generate "new" population and employment growth without
more in-depth evaluation of total growth trends by sector
in Ada County-
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Regarding population increases in both Middlebrook and
the Southwest Area, the general conclusion of Gruen Gruen +
Associates is that if the overall population forecast for
the county is accurate, then increases in one subcounty
planning area imply decreases in the remaining planning areas.
To state this conclusion in slightly different terms, adding
additional population to a given planning area does not in
itself affect the accuracy of the countywide population pro-
jection .
How Will Grant Eligibility Be Determined?
EPA's policy regarding grant eligible population pro-
jections was presented in Section 1. Unless the 208 plan
is formally amended, grant eligibility for the design and
construction of wastewater facilities will be based on the
208 plan DED population projections, assuming these are approved
by EPA. Higher projections may, however, be analyzed in
Step 1 facilities planning.
Are There Other Proposed Major Land Developments
Which Could Increase Population Projections?
Preliminary contacts with planning agency staffs in
Ada County have not indicated awareness of additional proposed
major land developments (other than Middlebrook) which would
call for reexamination of the DED population projections.
This tentative conclusion will be verified as part of further
work on the EIS.
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APPENDIX A
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Memorandum from Gruen Gruen + Associates
564 Howard Street
San Francisco
California 94105
(415)433-7598
rvk
Date:
Subject:
From:
To:
January 31, 1980
Economic Evaluation of Proposed Population Increases
in. the Southwest Area and Middlebrook
Roberta Mundie
Gruen Gruen + Associates
Socioeconomic Consultants
Jones & Stokes Associates, Inc.
2321 "P" Street
Sacramento, California 95816
Our Understanding of the Issues
The Ada County Planning Association, in its August 1978
report titled Demographic and Employment Distribution to
Year 2,000, sets forth a forecast of population and land use
distribution for county subareas, which in turn is based on
previous county-wide employment and population forecasts,
principally by the Idaho Department of Water Resources.
Two recent events have raised questions with regard to
the continuing accuracy of the basic forecasts: CD. the
proposal to construct a major employment, commercial and
residential center called Middlebrook west of Boise and south
of Eagle, and (2) an amendment to the 1978 population/land
use projections adding 7,010 to the southwest area. The basic
question is whether these increases - Middlebrook and South-
west - have been anticipated in and form part of the overall
growth projection for the county in the DWR model.
The Southwest issues relate purely to population. The
Middlebrook issues relate primarily to the adequacy of the
employment forecast. This memorandum first reviews the fore-
casting model briefly, and then considers the employment and
population issues posed by Middlebrook and the Southwest.
The IPEF Model and Its Local Application
The Ada County forecasts of employment and population
were prepared using a computer-assisted model called the IPEF
model, which means Idaho population and economic forecasting
model. This model generates separate population and economic
C-26
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forecasts; then relates each to the other by comparing labor
force estimates from the population outputs to labor force
requirements from the employment outputs; then adjusts the
population forecast by permitting a migration factor to change
to bring labor force availability and need into balance.
What the model produces is a forecast, at five-year intervals,
of County employment and population to the year 2000. The
Ada Planning Association drew primarily on the IPEF forecasts
for the basic data it then applied in forecasting population
by subareas of the County.
Two kinds of basic questions can be raised about the
accuracy of the IPEF forecasts and their application: questions
of magnitude and questions of distribution. The Middlebrook
issues relate primarily to magnitude and the Southwest issues
to distribution.
Middlebrook Employment
The proposed Middlebrook project, as described in a
June 5, 1979 memorandum from the Ada County Zoning Department
to the APA Board, would consist of about 250 acres of em-
ployment uses in a "technological park" and about 700-800
dwelling units, together with some commercial and public uses.
While the employment effects of the project will not be
finally known until lease-up and occupancy, the intention of
the developer is reportedly to establish a technological park
on 250 acres. The tech park, if it has a character similar
to the Hewlett-Packard project now under construction, would
accommodate over 7,500 jobs in the electronics industry -
This employment would be "basic" in the economist's terms
because most of the production would be exported to markets
outside the Boise region.
The question is whether the IPEF forecast anticipated
this level of growth in the electronics industry, which is
part of the "other manufacturing" sector in the forecast.
Table 1 presents the IPEF forecast of employment in other manu-
facturing, of total employment and of population through the
year 2000.
Gruen Gruen + Associates
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Table 1
IPEF Employment and Population Forecasts
Other Manufacturing Total Population
(excludes food & kindred Employment
and wood products sectors)
Number% of Total
1972
(base year) 3,044 5.3 57,085 120,600*
1975 2,861 4.2 67,529 136,140
1980 3,837 4.6 82,809 166,340
1985 4,430 4.6 95,495 192,380
1990 5,002 4.5 110,501 222,810
1995 5,773 4.5 127,712 254,800
2000 6,676 4.5 149,012 293,580
*1972 population estimate supplied by R. Meale to Jones & Stokes, verbal
communication, June 25, 1979.
Source: Meale and Weeks, Population and Employment Forecast, State of Idaho,
Series 2: Projections 1975-2000, published by Department of Water
Resources and Boise State University, July 1978.
The first column of Table 1 shows employment in the other
manufacturing sector of which Hewlett-Packard and other firms
would be part. Between 1975 and 2000, employment growth in
that sector is forecast at 3,815 jobs. That increase is not
sufficient to cover the Hewlett-Packard employees, let alone
7,500 additional tech park job-holders. Based strictly on
the sector forecast, it does not appear that IPEF incorporates
this magnitude of growth.
The model can be adjusted to reflect this unanticipated
change (of which 7,500 jobs are still only in the conceptual
stage). That effort should supplement mathematical modeling
with true field research looking into the comparative desir-
ability of Boise as a manufacturing location for firms like
Hewlett-Packard, as it seems evident that abstract formulations
can overlook important alterations in a region's economic
capacity.
Gruen Gruen + Associates
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Other aspects of the model can be re-examined at the
same time. One important example is the employment-to-
population ratio, which, is held constant at about 0.5
jobs per^1.0 persons in the population throughout the 1975-
2000 period. Most commentators believe we will continue
to see a rising ratio during this period as we have in the
recent past.
The failure of the model to account for sector growth
does not necessarily mean that the overall employment-
estimate is too low. Low estimates in one sector may be
offset by too-high estimates in others (.for example, wood
products employment is forecast to increase 550 percent
between 1975 and 2000). . But without a more in-depth eval-
uation of the model's assumptions and operations, it is not
possible to reach a conclusion on this subject. Because
employment and population are interactive, it is also not
possible to reach a conclusion with regard to the magnitude
of the population forecast.
The Southwest Area and Middlebrook Population
It is important to recognize that, while new jobs in
basic industry cause growth, housing provision simply
accommodates growth. The population housed in the new
units, while they may affect the accuracy of this distribu-
tion projection, do not affect the accuracy of the population
forecast itself. Thus, the projected 2,000 to 2,500 new
residents in Middlebrook's 700 to 800 housing units and
the 7,010 people added to the Southwest area in the amend-
ment to the distribution plan do not alter the overall
population forecast; they alter only the manner in which
that population distributes itself on the land. If the
overall population forecast is accurate - and that is a
function of where jobs are, not where houses are - then a
decision to add households to one area (or a recognition that
more households want to move there than was previously
anticipated) will be complemented by a downward shift in the
number of households in other areas.
There are two major influences on such population
distribution: public policy and consumer preferences. In
certain highly-regulated areas, where the demand for housing
clearly exceeds the potential supply, it is sufficient to
know the capacity of the land under current zoning to
forecast housing unit provision, and therefore population.
In a situation such as Ada County's, however, this highly
restrictive condition does not appear to exist, and the
housing consumer may have a number of choices with regard
Gruen Gruen + Associates
C-29
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to residence location. Under these circumstances, such
factors as consumer preferences (which reflect, among
other things, varying land costs among different communities
and variations in neighborhood character and conditions)
must also be consulted to help make a distribution plan more
accurate.
Unresolved Issues
The most important hidden question which Middlebrook
poses is, 'how much more economic growth unanticipated by
IPEF's sector analysis is likely to take place? Simply
adjusting the current forecast to add in 12,500 electronics
jobs by 1990 is quick band-aid approach, but only a more
thorough review of the forecast can help shed light on
what other changes from past conditions Boise can expect
in the future.
Gruen Gruen + Associates
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BIBLIOGRAPHY
Persons Consulted
Barker, S. January 1980. CH2M Hill, Boise.
Minter, R. January 1980. Ada County Planning Association,
Boise.
Reference Documents
Ada County Planning Association. 1978. Demographic and employ-
ment distribution to the year 2000. Boise.
Idaho. Dept. of Water Resources. 1978. Population and employment
forecast, State of Idaho, series 2: projections 1975-2000.
Prepared with Boise State University.
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Appendix D
DRAINAGE
Prepared by:
Jones & Stokes Associates, Inc,
2321 P Street
Sacramento, CA 95816
January 1981
-------
TABLE OF CONTENTS
Appendix D - DRAINAGE
Introduction
Nature and History of the Problem
Impacts
Recommended Mitigations
BIBLIOGRAPHY D-i
D-i
-------
Appendix D
DRAINAGE
Introduction
The following discussions of the drainage situation
in Ada County are excerpted from the Drainage Task Report
in drainage planning and institutional evaluation, which
is a separate task report by Jones & Stokes Associates, pre-
pared as part of this EIS. The task report was widely dis-
tributed to drainage and regional planning agencies in
February 1980, and was discussed at a workshop in March 1980.
The report is available in the EPA district office in Boise.
Nature and History of the Problem
The problems are currently manifested by flooding with
property damage during heavy storms; overflow of the irrigation
canals and ditches which intercept runoff from urbanizing
rural areas; concern by irrigation districts regarding urban
pollutants in runoff water; varying quality and effectiveness
of drainage facilities installed by developers; damage to,
failure of, and nuisance conditions from unmaintained drainage
facilities; and vocal concern about present and future drainage
problems by local government officials. In the future these
problems are likely to intensify as new areas,-particularly
the Southwest area, are urbanized.
The problems are complicated by the complex drainage
patterns that have evolved in conjunction with the irrigation
canals and ditches, particularly in the Southwest area of
the county. Irrigation canals divert water from the Boise
River, and convey that water to the bench lands away from
the river. Natural drainage courses flow generally toward
the river, perpendicular to the irrigation canal. Histori-
cally, most of the drainage has been intercepted in the
irrigation canals, since the amount of runoff from the
relatively pervious soil is usually small and was handled
with no difficulty.
As urban growth changes the land uses in Ada County,
however, the runoff from rainfall and snowmelt has fewer
opportunities to percolate into the soil. As a result the
volume of runoff tends to increase and concentrate faster
from urbanized areas than from rural areas. This increased
peak runoff tends to swell the flow in natural drainage courses
and irrigation canals, overflowing canals and laterals. In-
creased storm runoff and runoff from lawn irrigation and
D-l
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other urban activities tend to keep the irrigation canals
flowing during most of the year, inhibiting maintenance
activities.
Water quality problems are likely to result from greater
quantities of urban pollutants entering the irrigation system.
It is possible that pesticides, heavy metals and other sub-
stances could enter the food chain through irrigation with
untreated urban runoff. The magnitude of such a threat is
difficult to determine.
In the Southwest area, the prospective development of
either low or high density residential land uses promises
to aggravate the problems of flooding and overloading of
irrigation canals, with resulting property damage, inter-
ference with irrigation operations, and strained relations
between governmental agencies and their constituents.
In the area alonq the foot of the Boise Front, develop-
ment is pushing into the foothills, providing more permanent
driveway and roof areas, and increasing the runoff tributary
to older areas of the city- During storms the downstream
facilities may become overloaded and flooding and property
damage may occur. As in the Southwest area, urban runoff
also enters the irrigation canals. These problems are also
likely to intensify as more homes are built along the front.
Erosion and deposition of sediment in drainage facilities
is a particularly serious problem in the developing foot-
hill areas.
Within the City of Boise, many of the older drainage
facilities are undersized and/or deteriorated, and even new
facilities tend to become overloaded from increased runoff
from developing tributary areas. Inadequate records of the
location, sizing and existence of storm drains further com-
plicates the problem.
No areawide approach to the solution and prevention
of these drainage problems presently exists. A master
drainage plan (JUB Engineers et al. 1973) was proposed for
the entire area in 1973 and adopted by Ada Council of
Governments (ACOG), the predecessor of Ada Planning Associa-
tion (APA) . However, the plan was never adopted by the city,
county or special district agencies responsible for managing
development. The plan emphasizes a tempered structural
solution to drainage needs; that is, conventional storm
drainage pipes, with detention ponds to reduce peak flows.
One variation of the plan proposed discharging some runoff
to irrigation canals, while the other proposed to keep the
waters separate to a significant degree. The costs were
estimated at $21,390,000 and $23,470,000, respectively, in
1973 dollars.
D-2
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Ada County has required each new development in the
unincorporated areas to provide for its own drainage needs,
following the approach of retarding flows and releasing
drainage water at the same quality and rate of discharge
as occurred prior to development. The responsibility to
oversee the design and construction of the drainage facili-
ties has largely rested with the County Engineer. The cities
and irrigation districts, which have review authority, had
delegated much of this authority to the County Engineer.
In August 1979 the County Engineer gave back most of
his drainage review authority to the underlying local agencies
(cities and irrigation districts). He retains review
authority over unincorporated areas not within the irri-
gation districts. This has further fragmented the provision
of drainage facilities in unincorporated areas, although
the irrigation districts had previously been involved in
drainage to some degree. Subsequently, in October 1980,
the City of Boise delegated its drainage review authority
to the Ada County Highway District.
When the irrigation districts reviewed development pro-
posals in the past they generally balked at accepting any
new quantities of runoff water from urban development. The
districts were concerned both with degraded quality and with
increased flow rates. The irrigation districts do provide
drainage services which may be interpreted as the removal
of excess applied irrigation water, and also as the removal
of normal rainfall and snowmelt runoff. But the districts
have generally refused to accept direct urban runoff. When
the peak flows are reduced to a rate equivalent to natural
runoff and some treatment is accomplished in detention basins
or overland flow, the districts have usually approved the
development plans.
Under the current approach, each developer's engineer
designs a drainage system to achieve the discharge objectives,
generally incorporating some form of on-site retention or
detention pond. A variety of facilities exists, and their
relative success varies. Most importantly, once the developer
has completed construction there is usually no apparent main-
tenance by developers. The developer may continue to hold
title to the land occupied by retention or detention ponds,
although if he fails to pay the property taxes, the land
reverts to county ownership. No agencies have been willing
to accept title to these facilities. In many cases a property
owner's association is formed with one of its duties being
the maintenance of these drainage ponds; however, rarely
do these associations function properly to carry out this
maintenance.
D-3
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The Ada County Highway District (ACHD) has in the past
performed some maintenance, but the agency does not have
funding or legal authority to assume these maintenance res-
ponsibilities at present. As a result of tax limitation
legislation, the ACHD budget has been reduced, eliminating
even occasional maintenance of any drainage facilities except
those associated with county highways.
There are many small subdivision areas along the Boise
Front and in the Southwest area that have been developed
with retention pond facilities in the last few years. Most
of these ponds are not maintained; they exhibit this lack
of maintenance in erosion, decreased capacity, furtively
dumped solid waste, and weeds and brush that constitute a
fire hazard.
In the Southwest area relatively flat conditions prevail
and the ponds tend to be continuously wet from surplus lawn
irrigation, car washing and other outdoor water uses._ Weed
growth and mosquitos tend to be problems associated with
these ponds. Silts and sediments, as well as organic debris
from vegetative growth tend to fill the ponds and decrease storage
capacity. Wet ponds with aquatic growth may support some wild-
life that otherwise would be absent from the urban fringe areas.
The ponds tend to be an attractive nuisance and could attract
children. The potential for drownings and injuries related
to pond use does exist, even when the ponds are fenced. Many
fences are improperly designed, constructed, and maintained.
Access to ponds for maintenance is often difficult, and pond
construction itself may make maintenance difficult.
Inconsistencies in drainage design criteria between
agencies contribute to fragmented solutions. The 1973 master
plan (ACOG 1973) proposed use of flood recurrence criteria
of once in 5, 10, 50 and 100 years depending on land use
or watershed. This can lead to arbitrary expansion and con-
traction of capacity as a storm drain passes through areas
of various land uses. City of Boise law requires use of
a 50-year design storm, but this has been largely ignored
in favor of the criteria adopted in the 208 plan Urban Runoff
Control Handbook (CH2M Hill, Inc. 1977) . Those latter cri-
teria propose use of 5-, 10- and 25-year return storms de-
pending on land use. The County Engineer has also used these
criteria for the last few years, and it is expected that
the irrigation districts will also apply them to projects
under their review. The City of Boise is presently reviewing
its criteria.
The Flood Insurance Act of 1968 requires protection
and property improvements from a 100-year frequency storm
and provides for the preparation of maps delineating areas
of flood risk, seeks to prohibit new property improvements
within flood hazard areas (unless protected by effective
flood proofing measures), and provides a means of obtaining
D-4
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insurance to cover flood risk exposure of existing improvements.
This federally-mandated program is being implemented in Ada
County through preparation of the flood hazard maps, implementa-
tion of floodplain regulations and provision of floodplain
insurance. The flood hazard maps, however, follow major
existing streams and the Boise River only, and do not de-
lineate the flood hazards from 100-year floods in much of
the Southwest area and in some of the front area. It is
probable that continuing development of the unincorporated
area of the county under 5-, 10-, and 25-year design criteria
will inevitably expose new property improvements to flood
damage from 100-year events.
In conclusion, the principal drainage problems are
perceived as:
o Flooding and property damage from inadequately
handled runoff.
o Overflow of irrigation canals and ditches due to
increased urban runoff.
o Probable increase in pollutants in irrigation canals
and other surface waters due to increased urban runoff.
o Inadequate function of existing drainage systems.
o Development of nuisance conditions at retention and
detention ponds due to lack of maintenance.
o An intensification.of these problems accompanied
by public dissatisfaction as urban development
continues.
The basic causes of these problems are perceived as:
o Lack of areawide drainage planning.
o An uncoordinated piecemeal approach to drainage on
a development-by-development basis.
o Lack of an areawide agency or group of agencies
with effective control of drainage management.
o Lack of consistent and adequate criteria for storm
drainage design and 100-year flood flow planning.
o Lack of maintenance for existing drainage facilities.
o Lack of funding for planning, facility implementation,
maintenance and administration.
D-5
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Impacts
Through increased sewage capacity and land use planning,
the stage appears set for additional development to occur
in Ada County. Based on current drainage planning and insti-
tutional responsibility a likely future scenario can be pro-
jected. It is likely that a large number of retention ponds
will be built, each designed to serve an increment of the
development. The irrigation districts in some cases are
likely to perform thorough reviews and in other cases in-
complete reviews. As time goes on, the unmaintained ponds
are likely to become nuisances, helping to breed mosquitos,
causing weed growth, constituting safety hazards, filling
with sediment and debris and failing to operate when needed
most. Property damage from flooding will be very likely
during moderate to heavy storms; irrigation canals will be
overloaded and will likely suffer more frequent damage with
the irrigation districts possibly bypassing runoff to lands
that have been protected from upstream runoff for decades.
Governmental agencies at all levels will be increasingly
pressured by their constituents to solve the problems. The
funding will probably have to come from these same consti-
tuents to provide makeshift solutions, and hopefully, some
consistent areawide solution to the storm drainage problems.
By the time events have run their course to this point it
is likely that expensive underground storm drain pipes and
concrete-lined channels will be the only feasible solution.
Costs of $5,000-$10,000 per acre are not unusual for such
systems.
While the above scenario may seem extreme to some, it
has been repeated with many different variations in many
areas of the country. Southern California and suburban
Seattle are typical examples of areas where many older
communities faced expensive flood protection costs to correct
inadequate construction in earlier years. There, many of
these flood control costs were borne by residents during
later years, rather than as a development cost when the
areas were first urbanized.
Recommended Mitigations
The adverse impacts of new development within the physical
and institutional environment related to drainage in Ada
County can be mitigated by implementing a number of measures.
EPA may consider these mitigations for inclusion as grant
conditions on funding for the facilities covered by this
EIS.
D-6
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Designate an agency, preferably the ACHD, (secon-
darily Ada County or thirdly a new entity) and
possibly including the incorporated cities, to
implement countywide drainage planning, facility
implementation, maintenance and administration.
Seek legislative clarification to provide full
drainage authority and funding to the agency for
all appropriate functions.
Develop, adopt and implement consistent drainage
criteria for storm drain design and for provision
of flow routes for runoff from the 100-year event
without property damage consistent with the National
Flood Insurance Act.
Prepare, adopt and implement drainage master plans
indicating flow volumes for storm drain design and
100-year flood flows, and specifying facilities
or concepts. The plans should provide for funding,
and should involve a consistent approach to the
separation or combination of storm drains with
irrigation facilities.
D-7
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BIBLIOGRAPHY
Reference Documents
CH2M Hill, Inc. 1977. Urban runoff control handbook for
Ada and Canyon Counties. Prepared for Ada/Canyon Waste
Treatment Management Commission. 46 pp. + tables + figs.
Jones & Stokes Associates, Inc. 1980. Draft drainage task
report: drainage planning and institutional evaluations.
Prepared for U.S. Environmental Protection Agency. 51 pp.
J-U-B Engineers, Inc., and Barton, Stoddard, Milhollin & Higgins.
1973. Boise metropolitan area storm sewer system general plan.
Prepared for Ada Council of Governments. 48 pp. + tables +
appendix + figs.
D-8
-------
Appendix E
PARTIAL SPECIES LIST
Ada County
Prepared by:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
July 1980
-------
Partial List of Plants and Animals Occurring in Ada County1
Common Name
Scientific Name
PLANTS
M
I
Horsetail
Ponderosa pine
Douglas-fir
Cattail
Arrowhead
Bluebunch wheatgrass
Crested wheatgrass
Cheatgrass
Bermuda grass
Idaho fescue
Foxtail barley
Indian ricegrass
Rabbitfoot grass
Needle-and-thread
Three-awn
Bulrush
Sedge
Hanna Aase's onion
Cottonwood
Willow
Four-winged saltbrush
Shadscale
Greasewood
Russian thistle
Currant
Wild rose
Mulford's milkvetch
Bitterbrush
Big sagebrush
Rabbitbrush
Equisetum spp.
Pinus ponderosa
Pseudotsuga menziesii
Typha latifolia
Sagittaria cuneata
^3L9.PY:T°_n spicatum
A. cristatum
Bromus tectorum
Cynodon dactylon
Festuca idahoensis
Hordeum jubatum
Oryzopsis hymenoides
Polypogon monspeliensis
Stipa comata
Aristida longiseta
Scirpus spp.
Carex spp.
Allium aaseae
Populus spp.
Salix spp.
Atriplex canescens
A. confertifolia
Sarcobatus vermiculatus
Salsola kali
Ribes viscossimum
Rosa woodsii
Astragalus mulfordae
Purshia tridentata
Artemesia tridentata
Chrysothamnus spp.
Common Name
Scientific Name
Abundance'
Spring
Summer
Fall
Winter
ANIMALS
Mammals
Spotted bat
Mountain cottontail
Black-tailed jackrabbitt
Euderma maculatum
Sylvilagus nuttal'lii
Lopus californicus
Rare ;
L
L
L
L
L
L
L
L
-------
Cont'd.
i
to
Common Name
Snowshoe hare
Least chipmunk
Yellow-bellied marmot
White-tailed antelope squirrel
Townsend ground squirrel
Golden-mantled ground squirrel
Red squirrel
Pocket yophcr
Ord kangaroo rat
Deer mouse
Bushy-tailed woodrat
Muskrat
House mouse
Porcupine
Coyote
Kit fox
Raccoon
Badger
River otter
Striped skunk
Bobcat
Elk
Mule deer
Birds
White pelican
Great blue heron
Black-crowned night heron
Canada goose
Mallard
Green-winged teal
Blue-winged teal
American wigeon
Sharp-shinned hawk
Red-tailed hawk
Swainson's hawk
Ferruginous hawk
Golden eagle
Bald eagle
Marsh huwk
Osprey
Prairie falcon
Peregrine falcon
Kestrel
Blue grouse
Ruffed grouse
Sharp-tailed grouse
Sage grouse
Bobwhite quail
Mountain quail
California quail
Abundance 2
Scientific Name
Lepus americanus
Eutamias minimus
Marmota flaviventris
Ammospermophilus leucurus
Spermophilus townsendi
Citellus lateralis
Tamiasciurus hudsonicus
Thomoimys spp.
Dipodomys ordi
Peromyscus maniculatus
Neotoma cinerea
Ondatra zibethica
Mus musculus
Erethizon dorsatum
Canis latrans
Vulpes macrotis
Procyon lotor
Taxidea taxus
Lutra canadensis
Mephitis mephitis
Lynx rufus
Cervus elaphus
Odocoileus hemionus
Pelecanus erythrorhynchos
Ardea herodias
Nycticorax nycticorax
Branta canadensis
Anas platyrhynchos
A. crecca
A. discors
A. americana
Accipiter striatus
Buteo jamaicensis
B. swainsoni
B. regalis
Aquila chrysaetos
Haliaeetus leucocephalus
Circus cyancus
Pandion haliaetus
Falco mexicanus
F. peregrinus
F. sparverius
Dendragapus obscurus
Bonasa umbellus
Pedioecctes phasianellus
Centrocercus urophasianus
Colinus virginianus
Oreoriiyx pictus
Lophortyx californicus
Spring
L
M
L
M
M
L
L
M
M
M
L
L
M
L
M
L
L
M
L
L
L
L
M
L
L
L
L
M
M
L
M
L
M
L
L
L
L
L
L
L
M
L
L
L
L
L
L
L
Summer
L
M
L
M
M
L
L
M
M
M
L
L
M
L
M
L
L
M
L
H
L
L
M
L
L
L
M
M
M
M
M
L
M
L
L
L
L
L
L
L
Rare3
M
L
L
L
L
L
P
L
Fall
L
M
L
M
M
L
L
M
M
M
L
L
M
L
M
L
L
M
L
L
L
L
M
L
L
L
M
M
M
M
M
L
M
L
L
L
L
L
L
L
M
L
L
L
L
L
P
T.
Winter
L
M
L
M
M
L
L
M"
M''
M"
L
M
L
M
L
L
M
L
L
L
L
H
P
L
L
L
M
M
L
M
L
M
L
L
L
L
L
L
M
L
L
L
L
L
P
-------
Cont 'd.
M
I
OJ
Abundance2
Common Name
Ring-necked pheasant
Chukar partridge
Hungarian partridge
Killdeer
Long-billed curlew
American avocet
California gull
Rock dove (domestic pigeon)
Mourning dove
Burrowing owl
Common nighthawk
Belted kingfisher
Common flicker
Western kingbird
Horned lark
Black-billed magpie
Common raven
Common crow
Mountain chickadee
Red-breasted nuthatch
House wren
Robin
Mountain bluebird
Cedar waxwing
Loggerhead shrike
Starling
Warbling vireo
House sparrow
Western meadowlark
Yellow-headed blackbird
Red-winged blackbird
Brewer ' s blackbird
Pine siskin
American goldfinch
Rufous-sided towhee
Savannah sparrow
Grasshopper sparrow
Chipping sparrow
Reptiles
Western terrestrial garter snake
Common garter snake
Western ground snake
Desert night snake
Western rattlesnake
Western fence lizard
Sagebrush lizard
Amphibians
Leonard frog
Spotted frog
Scientific Name
Phasianus colchicus
Alectoris chukar
Perdix perdix
Charadrius vociferus
Numenius americanus
Recurvirostra americana
Larus californicus
Columba livia
Zenaida macroura
Athene cunicularia
Chordeiles minor
Mogaoeryle alcyon
Colaptes auratus
Tyrannus verticalis
Eremophila alpestris
Pica pica
Corvus corax
Corvus brachyrhynchos
Parus gambeli
Sitta canadensis
Troglodytes aedon
Turdus migratorius
Sialia currocoides
Bombycilla cedorum
Lanius ludovicianus
Sturnus vulgaris
Vireo gilvus
Paser domesticus
Sturnella neglecta
Xanthocephalus xanthocephalus
Agelaius phoeniceus
Euphagus cyanocephalus
Spinus pinus
Carduelis tristis
Piplio erythrophthalmus
Passerculus sandwichensis
Ammodramus savannarum
Spizella passerina
Thamnophis elegans
T. sirtalis
Sonora scmiannulata
Hypsiglena torguata deserticola
Crotalus viridis
Sceloporus occidentalis
S . g_rac iosus
Rana pipiens
R. prctiosa
Spring
M
L
L
M
L
L
M
M
L
L
L
L
L
L
M
M
M
L
L
L
M
L
L
L
M
M
M
M
M
M
L
L
L
M
M
L
L
M
M
M
M
M
M
II
M
M
Summer
M
L
L
M
L
L
M
Common3
M
M
L
L
L
M
M
M
M
M
L
L
M
M
L
L
M
M
M
M
M
M
M
L
L
M
M
M
M
M
M
M
M
M
M
M
H
M
M
Fall
M
L
L
M
L
L
M
M
M
L
L
L
L
M
M
M
M
L
L
L
M
L
L
L
M
M
M
M
L
L
L
L
L
M
M
M
M
M
M
M
M
M
M
H
M
M
Winter
M
L
L
M
P
L
L
L
L
L
L
L
L
L
M
M
M
L
L
L
L
L
L
L
M
P
M
M
L
L
L
L
L
L
L
L
L
M
M
M
M
M
M
II
M
M
-------
Cont'd.
SOURCES: Peterson 1961; Stebbins 1966; Holmgren 1972; Ada Council of Governments 1973a; Burt and Grossenheider 1976; Idaho Depart-
ment of Fish and Game 1977; U. S. Bureau of Land Management 1980.
'Abundance from Idaho Department of Fish and Game 1977.
H = High L = Low
M = Medium P = Population level unknown
'Abundance of this species not listed by Idaho Department of Fish and Game (1977). Abundance shown on this table taken from U. S.
Bureau of Land Management (1980).
"Idaho Department of Fish and Game (1977) did not list abundances of individual species of gophers, kangaroo rats, white-footed
mice, and woodrats. Abundance shown is that listed for the species group.
-------
Appendix F
HOURLY CARBON MONOXIDE EMISSIONS BY COMMUNITY
PLANNING AREA: 1977, 1980, 1987, AND 2000
Prepared by:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
February 1981
-------
Table F-l. Hourly Carbon Monoxide Emissions Summary for 1977
(CPA 1)
Southeast Area (10)
Northwest Subarea (21)
CBD Subarea (22)
T
M
West Bench Area (30)
Component
Parking
Parking
Total
Highway Traffic
Total
Total
Parking
Total
Residential Fuels
Total
Parking
Total
Parking
Total
1
287
186
128
0
80
675
78
777
55
0
95
146
593
891
919
49
500
1,468
181
186
86
0
80
78
494
55
0
95
128
479
589
11
500
1,100
90
186
42
0
80
78
287
55
0
95
110
379
295
9
500
804
60
186
29
0
80
219
55
0
95
106
344
209
9
500
—JIB
60
186
29
0
80
78
219
55
0
95
338
295
9
500
121
186
57
0
80
78
358
SJ>
0
901
633
15
500
1,148
Average Hourly Emissions (pounds)
7 8 9 10 11 12 13 H
270
479
1, 305
184
281
0
321
1,432
18
2,881
1,731
22
1,683
3, 436
27G 282
270 270
2,218 2,146
5,961 5,910
184 184
1,072 1,033
384 373
321 321
1,254 1,21-1
5,07-1 4,904
1,48-1 1,523
12,837 12,270
9,026 8,479
1,865 1,903
1,683 1,683
12,574 12,065
119
270
1,500
4,762
184
720
384
117
321
690
Hi
6, 127
765
if! 575
270
4,914
184
774
168
321
6,382
1,175
1,683
9,240
165
270
1,817
6,030
184
832
121
321
~TT8
7,463
1,063
1,683
10,209
157 19.)
182 182
1,858 1,8-12
6,684 6,528
B27 836
216 216
842 880
8,281 7,930
1,041 1,325
1, 133 1,133
10,455 10,388
15 16 17 18
128 128 12 123
182 192 18 182
1,706 1,816 1,98 2,003
6,117 6,476 7,422 7,327
752 798 931 929
216 216 216 216
7,654 8,331 9,4 3 9,619
820 829 1,0 6 948
1,133 1,133 1,1 3 1, 133
9,607 10,293 11,682 11,700
19
728
T7323
4,212
333
6^8
575
4,665
589
8,265
20
591
T7T7I
3,566
271
626
53
575
3,757
562
3,011
7,330
21 22 23
271 HI 212
465 448 368
3,048 2,808 2,267
216 212 172
000
575 575 575
754 747 716
395 128 68
3,067 2,963 2,423
260 110 88
3,011 3,011 3,011
6,338 6,084 5,522
2-5
172
271
^754
i.,239
1,727
123
329
452
101
0
575
67?
2,292
35
1,770
37
3,011
4,818
Daily
(Pound si
6,353
14,111
19,674
27^933
74,882
89,720
8, 391
4,141
13,642
6,821
1,9-12
7,244
40 ,768
21,120
66,813
14, 116
112, ini
14,562
37.9F3
164 ,626
-------
Table F-l (cont'd.)
I'.'PA 1 1
5r.uthwr.Ht ftrci (SO)
Meridian (601
t.lqlc (70)
ro
Kuna (80)
Rural Aria County (90)
Total
Notes i
Component
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuela
Total
Parking
Residential Fuels
Total
Parking
Residential Fuela
Total
Parking
Residential Fuels
Total
Parking
Residential Fuels
1 2
481 317
15 15
615 451
3,809 ,441
137 60
1,774 .,774
5/fTO i,275
196 12B
0 0
93 93
~~2T9 ~22l
0 0
42 42
"To? §4
0 0
—5? -T7
0 0
717 512
139 55
2.036 2,036
Average Hourly Emissions (pounds)
3 4 5 6 7 8 9 in 11 12 13 14 15
159
11
289
1,220
22
1,774
3,016
64
0
93
0
42
62
0
55
0
309
22
1 5
3
2 7
8 3
#4
42
0
93
0
42
5S
0
— n
0
2 4-0
24
170 370
4 19
293 507
1,024 2,157
15 46
\_fJT4 1 ,774
3,~B13 3,977
42 86
0 0
93 93
0 0
42 42
55 71
0 0
22 27
0 0
240 375
15 46
970
29
402
1,401
6 ,606
126
5 . 975
12,707
315
0
313
628
0
143
244
15
0
—51
0
1,353
128
5,756
505
6,663
38,976
6,711
S , 975
51,662
2,423
320
313
3,056
139
143
1,080
123
57
2,6
335
8,849
7,564
j, 344
514
402
6,260
36,809
6,865
5,975
49,649
2, 286
309
313
134
14 3
1,029
117
55
238
324
8,3.9
7,690
3,646
225
402
4, 273
26, Bll
2, 928
5, 975
35,714
1,618
99
313
44
143
62
18
166
104
5,798
3, 190
3,774
340
402
4,516
28, 185
4 .462
5,975
38,622
143
313
62
7~67
86
26
178
150
6, 140
4,839
1,433
402
5, 150
33,01 J
4, 109
5j 975
43,098
UU
313
44
14 3
846
101
18
66
~T85
106
7,095
4 , 378
J , 883
304
270
5,457
36, B97
4J020
44,768
82
211
2,
35
96
859
110
16
44
84
7,608
4, 363
i ,689 4,553
370 262
270 270
5,329 5,085
35, 114 33,626
5,229 3,519
1-LOJO 4 ,02J3
44, 38J 41 ,165
211 211
57 IB
96 96
854 782
108 101
24 7
176 152
137 44
7,412 6,986
16
t, 982
264
270
5,516
36, 379
3,560
41,020
43,959
211
18
96
833
110
9
163
44
46,632
3,675
17
5,670
430
270
6, 370
40, 90 6
4,742
4,020
49,668
2U
2,67
20
96
~907
121
9
46
8,231
52, 183
4,859
IB
5, 06
J2
70
6, 08
•11, 92
4, 92
4,020
49,704"
211
20
96_
9
174
46
8,251
4,409
19
2, 557
185
719
T74&T
19,791
2,485
10,689
32, 965
561
1 , 694
20
255
630
9
180
49
4,158
2,608
2,059
185
719
2,963
15,988
2,474
29"7i5T
561
20
255
564
9
11,9
49
20,022
2,597
21
1,651
1 26
719
T7496
12, 948
1,493
10,689
25,130
561
0
255
482
0
151
0
2,855
16, 125
1 ,490
1 ,574
f.O
719
2, 353
12,503
5H9
lp_(_6_89
23,841
56)
"1 , 236
218
0
255
473
0
151
0
2,766
586
1, 305
31
719
2, 055
10, 253
428
2T7T70
561
181
0
255
436
0
144
0
2,394
428
24
977
24
719
1, 720
7,433
284
10,689
18,406
561
132
0
255
387.
0
-Hi
0
1,931
287
Daily
Em -, 3 ! • '
(Pounds)
66, M '
4 ,678
gn=,3
484 , 917
58,740
134, 7J5
678,402
28,667
.7_,0.6f.
-JTTTso
S, 387
628
3,218
13,233
262
3,184
1,519
103, 588
618,405
62,607
15-1,583
-------
Table F-2. Hourly Carbon Monoxide Emissions Summary for 1980
(CPA 1)
7
U)
CBD Subatea (22)
Foothills Subarea (24)
Central Bench Area (40)
Emissions
Parking
Total
Residential Fuels
Total
Highway Traffic
Residential Fuels
Total
Parking
Total
Highway Traffic
Parking
Total
Parking
Total
Parking
Total
Highway Traffic
Parking
Residential Fuels
Total
"251
-iS
0
^139
64
0
114
178
0
288
647
2
1,491
1,019
49
522
1,590
Average Hourly Emissions (pounds)
228 228 228 228 228 767 767 767 767 767 767 516 516 516 516
479 340 303 303 382 1,329 4,808 4,620 3.514 3-8<>4 4,226 4,288 4,312 3,955 4,227
202 152 136 136 169 585 2,649 2~,~ 508 T7820 1»9« 2.2°8 2,236 2,210 2,039 2,185
585 338 256 256 424 1,523 6,747 6,651 5,531 6,013 6,926 7,661 7,436 6,949 7,404
000000 207 201 62 101 77 66 97 46 46
111 86 78 78 96 327 1,273 1,219 883 958 1,042 1,041 1,036 941 1,003
114 114 114 114 114 384 384 IB* ** 38" « "8 258 8 258
154 134 12.7 127 140 483 1,470 1,418 93 1.096 1, 31 1,041 1,073 5 984
0 0 0 0 0 t 891 869 98 «< " 333 «7 5 225
288 288 288 288 288 970 970 970 70 97° 70 652 65a 2 652
517 403 365 365 440 1,527 5,408 5,201 3, 74 4'19B ' • " 1.534 4,516 4, 7 4,340
0 0 0 0 2 18 ,477 1,517 9 '184 *' "4 \,\*1 1,391 1, 0 1,047
1,112 ' 764 658 693 984 3^232 1 ^466 13l?72 10 ' 2 L .100 12, 93 13,086 12,823 11, 4 12,834
653 326 234 326 699 1,900 ,795 9,136 6, 6 .117 B- " 9.158 8,730 d , 1 9,176
U 11 U 11 18 26 ,777 1,828 7 ."4 1, 04 1,202 1,459 0 1,003
522 522 522 52? 522 1,759 ,759 1,759 1, 5 ^iZA9 L 59 ij_18_3_ Itli3 1, 83 1_._1|3
T7I86 859 76~7 85~9 1,239 3,685 1 ,331 12,723 9, 98" 1 .170 11, 52 11,543 11,372 10,564 11,362
516 51
2,311 2,34
8,413 8,33
104 9
1,116 TTTT
686 69
258 25
1,112 1,11
282 26
652 65
4,669 4,72
1,215 1,10
9S1 95
13,917 13,98
10,185 10,37
1,208 1,09
127T76 1276T
1,371
1,637
4,848
37
826
1,099
209
1,734
3,808
765
2,528
81939
5,086
769
3,146
9,001
1,371
4,136
37
749
1,042
216
1,734
3,473
767
2,528
7,896
4,125
750
3,146
8,021
1,371
618
3,590
0
644
907
35
1,734
3,008
65
2, 28
6, 14
3, 89
66
3, 46
6, 01
1,371
27T49
618
3,323
0
637
903
15
1^734
2,966
148
2,528
6^305
3,300
139
3,146
6,585
1,371
618
2,668
0
533
866
4
1,734
2,734
77
5,594
2,7)6
108
3, 146
5,970
1,371
618
2,036
0
527
817
2
1,734
2, -155
42
4,671
1,997
49
T7192
Average
Winter
Eraissio
17,290
68, 329
7,788
102,955
1,182
8,428
8,66
19,35
5,19
21 ,86
72^80
15,28
189,79
122,98
16,14
39.G62
1787798
-------
Table F-2 (cont'd.)
ICPA II
Southmat Area (50)
BolM Hctropolitan Area
Subtotal
Meridian (60)
I
EaqU 170)
Kuna (SO)
Rural MA County (901
Northern Ad* County
Total
WOTKS i
Dnlaaioni
Highway Traffic
Parking
Pt-sidi_-ntial Fuels
Parking
Residential Fuels
Total
Highway Traffic
Pjrking
Total
Highway Traffic
Parking
Total
Highway Traffic
Parking
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Park.ng
Residential Fuels
Total
545 359
16 16
143 143
706 518
4,440 2,842
110 55
6,517 4 ,864
218 143
0 0
326 251
73 46
0 0
0 0
35 31
0 0
119 119
802 571
5,426 3,492
134 57
2.268 2,268
7,828 5,817
o rounding.
181
1 3
1,4 0
4
73
0
181
24
0
0
31
0
119
346
i,746
24
2,268
4,038
130
143
983
26
2,976
49
0
15
0
51
66
0
26
0
2 9
1,1 7
6
2.2 8
3,4 1
190
1. 107
20
3,094
49
0
IS
0
66
0
'• 26
0
269
1,387
20
TTeTs
Average Hourly Emissions (pounds)
2,4 6 7,533 44,259
9 130 6,790
4^45~2 14,~2B5 57,671
98 351 2,703
0 0 335
30 115 891
0 0 157
81 281 1,220
26 99 295
0 0 344
421 1,507 9, 809
2,866 9,125 57,069
49 130 7,692
2,268 1,639 7,638
5,185 16,893 72,399
6,962
55,139
2,531
322
838
150
1,160
284
8,481
331
9,212
24,287
7,833
7^636
39,758
3,038
43,817
1,870
104
617
49
638
202
6, 77
06
6, 83
40, 51
3, 18
7, 68
51, 07
5,294
4,971
44,683
i,969
168
650
77
899
220
6,490
172
7,062
5,421
7_J_6_38
55,364
4,632
49,850
2,304
123
761
57
990
228
7,608
126
8,134
4,963
7,638
61,996
T&
4,685
51,776
2,524
101
2,869
836
46
998
212
8, 322
101
8,692
4,956
5_, 139
64,547
5,747
50,941
150
802
71
989
214
8,00
15
8,42
6,15
5,_13
6T73F7
38,763
4,052
47,271
60
761
26
903
11
189
7,588
60
7,917
49,536
4,213
5,139
58,888
6,377
42,136
4,125
50,717
62
822
28
966
11
200
8,228
62
8,559
53,802
4,290
5,139
63,231
7,062
46,031
5, 333
55,820
64
875
28
1,019
13
209
8,669
64
9,002
56, 354
5,505
S, 139
68,996
7,146
46,823
4,822
56,101
66
884
30
13
209
8,733
66
9,068
59, 240
4,998
5, 139
69,377
22,791
3,104
37,742
68
403
30
13
223
66
4,705
28,409
3,287
13,664
45,360
2, 359
18,552
3,161
33,560
71
331
33
13
212
71
715
3,996
23, 151
3,351
11,664
40, 166
1,903
15,128
1,856
28,831
0
262
0
0
Tea
0
715
3,255
16,766
1,856
13,664
34,286
1,825
14,794
595
27 , 236
0
256
0
0
166
0
3,173
18,327
741
13_,664
32,732
1,523
12, 148
505
24,500
0
212
0
0
179
0
715
T7T6T
15,082
505
13,664
29,251
1 , 146
8,855
353
21,055
0
157
0
0
170
0
715
2, 230
11,023
353
13,664
25,0-10
Winter
Daily
Emission
(Pounds)
75,707
559,314
65,333
774,002
1,693
8,174
10,677
795
15,338
1,731
32B
1,731
9.019
116,878
710,H2
69,869
172.259
952,270
-------
Table F-3. Hourly Carbon Monoxide Emissions Summary for 1987
Comaunity Planning Area
ICPA tj
Southeast Area (10)
.'Jorthwest Area (21)
7
en
CBD Subarea (22)
Foothills Subarea (241
Morthend Subarea (25)
-Vest Bench Area (30)
Central Bench Area (40)
Emissions
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Total
Highway Traffic
Parking
Residential Fuels
Total
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
_^
1ft
714
117
191
553
110
674
S3
123"
64
0
163
205
0
683
TTfia
dB
2
na
77
340
35
105
H8
130
0
' 425
-TO
1,010
3__
HH
191
23T
170
—280
18
88
163
64
0
^n
787
4
— sir
-ffl
225
11
,i
i"
176
44
0
339
-m
719
5
465 526
191 191
217 244
225 337
11 22
44 86
0 0
339 ~ 381
661 ~ 837"
' 758 978
Average Hourly Emissions (pounds)
1,356
1.824
644
1,210
84
154
313
2
1 ,309
HM
3,109
4,895
G<4
77483
4,711
615
432
3 , 340
9,803
9,478
4,715 3,918 4,251 4,613
644 644 644 644
2,385 1,943 2,119 2,315
4,684 4,244 4,656 5/348
924 741 798 873
1,490 f,~201 1,303 1,374
9, 362 7,721 8,354 9,368
9,059 7,496 8,065 8,953
4,468 4,459
2,239 2,215
5,913 5,739
854 840
9,589 9,374
9,051 8,857
4,126 4,383
2,062 2,188
5,432 5V7.53
779 832
Jll 1,206
1.116 1,116
8,811 9,418
8,301 8,888
4,514 4,565
2,128 2,133
6,190 6,117
909 905
1,232 1,238
27,70 27^
1,116 1.116
9,652 9,701
9,234 9,307
**»
2,008
3.Q99
74,
rM
2.967
7,180
7.423
77082
1,880
17398
696
1,353
2,967
6,503
6,740
3,672
T7&T7
3,065
618
1,225
l^giV?
5,708
5,953
3,568 3,400
1..59B 1,516
2,633 2,150
614 579
1,214 1,175
1.778 1,776
2jJ>67 2,967
5,441 4,973
5,777 5.335
3,152
1,421
1,707
537
1.122
2,190
2,867
4,424
I777I
Average
Winter
Daily
Emission!
30,583
76,198
36,620
8,Jj-]6
79,040
5,3^5
14,092
23,559
22.415
51,829
96,139
9,592
37.407
143, 136
141,340
-------
Table F-3 (cont'd.)
ICKA II
Meridian (60)
I
E«9U (70)
Kun* (BO)
MOT US.
A Emission!
Parking
Residential Fuels
Total
Residential Fuels
Total
Parking
Total
Highway Traffic
Parking
Residential Fuels
Total
lliqhwjy Traffic
Parking
Residential Fuels
Total
Parking
Residential Fuels
Total
lliqhwjy Traffic
Total
1
13
185
584
68
108
0
269
0
0
152
591
3,677
2,895
6,640
to rounding.
13 9 11
185 185 185
454 322 286
31 15 18
71 35 24
000
161 161 161
?JS T96 T85
117 97 90
000
000
152 152 1S2
443 295 249
2.895 2,895 2,895
5,289 4 ,089 3,714
4 15
185 185
308 456
11 31
0 0
161 161
—185 207
90 103
0 0
43 45
0 0
152 152
249 346
3,797 4,749
Average Hourly Emissions (pounds)
24 335 346 163
1,370 5,722 5, 383 4,285
0 231 223 71
—715 2,092 2,003 1,630
355 1,166 1,107 891
0 53 51 16
15. 30, JM „!
511 511 511 511
1,219 6,523 6,150 4,980
6,023 38,696 36,315 30,166
15,854 53,024 50,780 41,994
4,552 5,169 5, 382 5,223 4,968 5,377 5,463
31 24 20 29 13 13 13
258 267 227 234 211 220 215
511 511 344 344 344 344 344
5,264 6,035 6,373 6, 175 5,827 6,277 6,050
45 ,' 228 50,393 51,192 50,152 47,008 50,216 51,281"
5,523 3,471 3,071 2,6 8 2,529
92 245 245 245 2J5
217 311 302 278 276
344 9)4 914 'J14
-------
Table F-4. Hourly Carbon Monoxide Emissions Summary for 2000
Cowiunity Planning Area
(CPA •)
Southeast Area (10)
Northwest Area (21)
CBO Area (22)
Warn Springs Subarea (23)
J
Foothills Subarea (24)
Horthend Subarea (25)
Heat Bench Area (30)
Emissions
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Total
Highway Traffic
Parking
Residential Fuels
Total
Highway Traffic
Parking
Residential Fuels
Total
Residential Fuels
Total
1
231
9
702
—942
79
0
336
—415
13
5
254
146
0
"450
618
Till 2
638
1,079
Average Hourly Emissions (pounds)
148
4
702
—854
53
0
-81
-18
37
0
254
93
0
-3,7
618
—935
638
—916
73
0
702
— TTS
26
0
336
362
90
254
46
0
— 350
638
~777
49
g
702
ie
0
HH
90
99
-m
31
0
335
-88
638
49
0
702
751
18
0
336
—243
90
254
267
31
0
304
335
618
7B~B
99
-si
35
0
371
—329
90
-Hi
62
0
366
618
927
-Ml
357
11
2,732
128
0
1,261
3"
223
1,246
2,081
3,150
2,147
3,018
2,811
478
5^653
1,160
207
2^500
535
4,140
855
1,660
1,440
2,664
2,081
8,889
2.147
7,009
474
57435
1,060
207
2^400
3,331
4,071
855
T78T4
1,356
2,578
2,081
8,201
fciS
187
4*773
917
84
77m
535
3,778
855
1,479
1,232
2,323
2,081
6,938
346
5,098
972
165
1,133
2,270
535
4,135
814
631
B55
1,541
1,327
2,478
2.081
7,366
304
5,598
1,157
148
1,133
2,438
535
4,896
— Ill
1,644
1,614
2,743
m
6,806
203
5,291
1,292
144
2,198
360
5,506
919
1,892
^7
875T4
6,661
381
5,205
1,243
174
77T79
360
17281
~ BB9
T7«74
1,795
2,611
T72S?
6,505
25G
47171
1,182
in
2,061
360
4,994
-"837
1,360
1,676
TT435
77954
4HS
16
3,386
269
1,590
5,245
1,287
117
I7T66
360
17393
905
1,424
J.,B30
7758?
8,805
1.445
6,778
17
335
1,590
5,287
1,190
115
2,067
360
5,662
947
1,376
1,863
2,635
9,198
1,445
6796T
18
328
5)207'
1,195
106
2,063
360
5,616
960
1,889
2.656
9,207
309
1.445
6,986
1,365
245
fcBi
496
104
27627
957
3,406
1,899
818
2,716
6^996
3^841
6,368
1,076
271
4,229
S.S76
401
104
ftni
957
2,950
541
759
278
1*530
1,837
642
HH
ftiff
3,841
S78B5
858
128
4.229
5,215
317
37
2.027
2,381
77645
700
518
^
ftSi
3,841
57418
636
75
4,229
5,140
306
2
2,027
2,335
\*,T46
511
27H?
Irni
1,435
3,841
still
681
75
47985
254
0
2,027
T72TT
2,086
~ 669
412
1,830
2,242
iTiff
i,175
57042
24
492
66
4,229
4,7B7
187
0
2,027
2,214
783
rM
93
634
1,660
293
1,830
T7T23
4,780
862
m
Average
Winter
Daily
Emission:
[Pound $ }
38,965
4,539
53,308
96,812
14,974
1,832
25.551
42,357
55,254
7,842
6,825
15,119
29,574
21,740
23,067
46,192
134,526
60,702
4J.425
113,569
-------
Table F-4 (cont'd.)
Average Hourly Emissions (pounds)
l< I A 1 )
t.nul hwrBt AH-.I r,OI
Subtotal
L.iqU [70}
7
00
Kuna (BO)
Rural Ma County (90)
Hiyhw,iy Traffic
forkinq
Rosi'J.MUiaJ Fuels
To I il
Parking
Total
Parking
Total
Parking
Total
Highway Traffic
Parking
Total
Highway Traffic
Residential Fuels
Total
Residential Fuels
Total
1
2 9
6 8
3
5,6 6
0
301
— 39!
0
139
7
0
84
302
210
512
4.132
6,797
2 3
299 299
504 405
13 9
4 'L8"14 i ' 1~ 09
0 0
361 330
0 0
4 2
0 0
84 84
201 101
210 210
411 311
5,840 4,988
4 5
299 299
377 400
9 4
3,891 3,996
0 0
301 301
321 321
0 0
148 148
2 2
0 0
84 84
68 68
210 210
278 278
4,723 4,829
b
9
299
522
15
4..M
0
301
341
20
0
159
2
0
84
132
210
342
5~!"58~9
7
15
l! 6 1~2
46
15,492
0
1 ,013
1,156
71
0
539
11
0
291
1, 191
4,711
13, 913
18,670
I,rt06
5,643
2 , 332
39, 121
201
1,013
2,451
648
1,211
95
51
281
5,107
31 ,594
13,913
48,316
1 ,006
5,211
2,425
37,047
194
1 ,013
3,342
584
90
49
261
4 ,805
13,913
45,758
1
1
32"
1
2
4
13
39
10
, 188
, nofi
,315
,089
tin
, 013
,052
492
989
79
15
281
,256
1~im
11
3,355
4 , 566
2,0 9
34,4 8
1,0 3
2,1 7
525
84
31
281
4,469
13,913
42,540
12
4 , 1 f . 0
1,006
5. 387
38,767
1,013
2,363
637
99
24
2B1
5,153
1 3 1 9 1 3
47,858
13
4,857
677
5,753
2 , (I 1 1
681
2,191
714
108
20
189
5, 374
1.J62
47,923
14
4 , 6 0 1
b77
65,525
2,381
37,873
681
2 , 160
688
106
26
189
5,215
9,362
46,620
15
4, 383
677
5,256
1 ,806
36,002
681
2 ,024
99
1 3
189
4 ,950
32,9> ,
44 ,270
16
4,941
5,816
1,821
39, 121
661
1,752
108
13
189
5, 323
36,656
27,969
17
4,943
5,891
2, 326
40,023
681
2,094
95
13
189
4,813
36,429
48^251
16
4,899
5, 851
39,924
681
2,096
95
15
189
4,833
36,577
48,179
1 , B FJ -1
3, 8 U
1,418
34,475
60
1, 912
2,428
28
42
1-3
5H3
3, 188
15, 342
41,794
1,444
W
1 , J r. r>
31,767
62
1,812
2,317
218
28
35
15
503
its .11
12,070
38,564
21
1,138
3,036
610
29,205
0
1,812
2,163
0
26
0
503
9,672
35,385
I ,091
2,925
271
287T38
0
1,812
2,152
0
Tool
26
0
503
2^35
9,396
34,558
; i
902
2,719
152
26 , 906
0
1 ,812
2,092
0
22
0
503
2,234
7,688
24,891
321733
24
675
2 , 487
1 10
25, 146
0
1,81 Z
2,017
0
938
15
0
503
1,983
5,602
aolinn
56 , 346
22^677
82,039
26,6 30
632, 175
16,440
1 ,204
22,840
40,484
562
10.555
19, 395
1,257
300
6,3-12
15,911
72,795
429,496
313,790
77^,753
-------
Appendix G
SUMMARY OF EXISTING CARBON
MONOXIDE MONITORING DATA
Prepared by:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
February 1981
-------
TABLE OF CONTENTS
SUMMARY OF EXISTING CARBON MONOXIDE MONITORING DATA
Introduction
ESL/CH2M Hill Study
EPA Study
Idaho Air Quality Bureau Study
Air Quality Bureau Monitoring Station Data
Idaho Transportation Department Monitoring Data
Summary
BIBLIOGRAPHY G-23
G-i
-------
LIST OF TABLES
Table Page
G-l Summary of CO Data Collected During 1974 G-3
ESL/CH2M Hill Study
G-2 Summary of CO Data Collected During the G-6
EPA Study
G-3 Summary of CO Data Collected During the G-9
1977-1978 Idaho Air Quality Bureau Study
G-4 Summary of CO Data From the Boise Odd G-l3
Fellows Hall Monitoring Station
G-5 Summary of CO Data From the Central G-l5
District Health Department Monitoring
Station
G-iii
-------
LIST OF FIGURES
Figure Page
G-l Monitoring Sites Used in the ESL/CH2M G-2
Hill Study
G-2 Monitoring Sites Used During the EPA G-5
Carbon Monoxide Study
G-3 Monitoring Sites Used During the Idaho G-8
Air Quality Bureau CO Study
G-4 Average Winter CO Levels at the Boise G-l6
Odd Fellows Hall Monitoring Station
G-5 Average Winter CO Levels at the Central G-l7
District Health Department Monitoring
Station
G-6 Time Periods With 8-Hour CO Levels >9.0 ppm G-l8
at the Boise Odd Fellows Hall Monitoring
Station
G-7 Time Periods With 8-Hour CO Levels >9.0 ppm G-19
at Central District Health Department
Monitoring Station
G-v
-------
SUMMARY OF EXISTING CARBON
MONOXIDE MONITORING DATA
Introduction
Ambient air quality monitoring in the Boise area has
focused on carbon monoxide (CO). The Idaho Air Quality
Bureau operates two permanent CO monitoring stations which
provide continuous monitoring data. The Idaho Transportation
Department operates a third continuous monitoring station
at its State Street offices. There have also been three
special CO monitoring programs which provide additional
data on the nature and extent of CO problems. There has
been a limited amount of monitoring for other pollutants.
Since data are limited for other pollutants, the focus of
this appendix will be on CO.
EPA has established two sets of ambient air quality
standards for CO. The standard for 1-hour exposures is
currently 35 ppm (parts per million), to be exceeded no more
than once per year at any air quality monitoring site. An
additional standard has been set for 8-hour exposures. This
standard (9 ppm averaged over a consecutive 8-hour period)
is also to be exceeded no more than once per year. In
practice, the 8-hour standard is more stringent than the
current 1-hour standard. EPA has proposed changing the
1-hour standard to 25 ppm, but no final action has yet
been taken.
ESL/CH2M Hill Study
The first significant air quality monitoring program
in the Boise area was conducted from January through May
1974. Monitoring site locations are shown in Figure G-l.
In addition to these monitoring stations, short-term bag
sampling was conducted at street intersections near four
of the five fixed stations. Table G-l summarizes the CO data
collected by continuous monitoring instruments during this
study. As can be seen from this table, the federal 8-hour
CO standard was exceeded at three of the five sites. At
the Eastman Building site, peak CO levels were greatest at
the lower of the two sampling positions. None of the short-
term bag sampling identified any violation of the federal
1-hour standard.
This study concluded that CO problems existed in the
downtown Boise area, and at some more outlying areas. It
was also concluded that areas on the first bench or higher
locations generally comply with the federal CO standards.
G-l
-------
FIGURE G-1. MONITORING SITES
USED IN THE ESL / CH2M HILL
STUDY
O
I
-LEGEND-
IT] FIRE STATION No.8
[T| FIRE STATION No. 6
[3 ITD BUILDING
H EASTMAN BUILDING
d] CH2M HILL BUILDING
-{ij- SITES RECORDING AT LEAST 1
" 8 HOUR CO VALUE > 9 ppm
SOURCE: REDRAWN FROM ESL INCORPORATED
AND CH2M HILL, 1974
v •
\
««< %" ,v
n
[
-------
Table G-l. Summary of CO Data Collected During
1974 ESL/CH2M Hill Study
o
1
U)
Monitoring Station
Eastman Building,
2nd Floor
Eastman Building,
6th Floor
CH2M Hill Building
State Highway Building
Fire Station No. 6
Fire Station No. 8
Month
January
February
March
April
May
January
February
March /April
March /April
April /May
April /May
Peak
1-Hour
CO (ppm)
23.0
24.0
21.8
18.9
23.7
20.4
21.3
16.4
20.3
10.5
6.3
Peak
8-Hour
CO (ppm)
14.9
16.3
12.5
12.5
19.6
12.3
15.5
6.4
9.5
9.3
2.5
Days with Peak
8-Hour CO
Above 9 . 0 ppm
6
13
9
2
16
8
7
0
1
2
0
Days of
Data
10
25
31
9
20
25
27
33
32
35
40
Notes: Federal 1-hour standard is 35.0 ppm, to be exceeded no more than once per year.
Federal 8-hour standard is 9.0 ppm, to be exceeded no more than once per year.
DATA SOURCE: ESL, Inc., and CH2M Hill, 1974.
-------
Wind data collected during this study indicated that
wind speeds measured at Boise airport were significantly
higher than those measured at the air quality monitoring
sites. In general, high CO levels occurred under low wind
speed conditions. Instruments on top of the six-story
Eastman Building recorded two instances during which wind ^
speeds were less than 2 mph for 8 consecutive hours. During
the study period, wind speeds of less than 2 mph were recorded
during 10.6-42.5 percent of the time at various monitoring
sites.
One unexpected result of the ESL/CH2M Hill study involved
the seasonality of high CO levels. Carbon monoxide problems
are generally most severe and most frequent during the winter
months (November through February). The observed frequency
of high 8-hour average CO levels during March, April, and
May was thus rather unexpected. Data presented in the ESL/
CH2M Hill report indicate that May 1974 was characterized
by frequent periods of low wind speeds.
EPA Study
The EPA conducted a 20-day study between November 25
and December 22, 1977. The study had four major objectives:
1) to obtain additional data regarding the magnitude of the
Boise CO problem, 2) to determine its spatial extent, 3)
to determine the representativeness of the permanent CO
monitor established in 1975, and 4) to assist in the selec-
tion of candidate sites for an additional permanent monitor.
This study collected consecutive 4-hour bag samples at 33
sites between 10:00 a.m. and 6:00 p.m. over a period of 20
weekdays. Sampling equipment from seven sites was shifted
to new locations during the last 10 days of the study,
resulting in 20 days of data from 26 sites and 10 days of
data from 14 other sites. In addition, CO data were collec-
ted at six indoor sites and along two pedestrian walking
routes.
Figure G-2 shows the locations of the 40 outdoor monitoring
sites. Monitoring results showed that elevated CO concentrations
are not limited to the central business district. High CO
levels were also measured along traffic corridors in areas
adjacent to the Boise central business district. The peak
8-hour CO level measured during this study was 17.2 ppm at
site 32 on December 22, 1977 (the last day of the study).
As is indicated in Figure G-2, only four of the twenty-six
4-week monitoring sites failed to record an 8-hour CO value
greater than the 9 ppm standard. On the other hand, eight
of the fourteen 2-week monitoring sites failed to record
any CO levels above the standard. Six of these eight sites
were operated only during the last 2 weeks of the study.
G-4
-------
23 I SITES USED FOR 20 DAYS
33A) SITES USED FOR FIRST TEN DAYS ONLY
*^s
29Bl SITES USED FOR SECOND TEN DAYS ONLY
-% SITES RECORDING AT LEAST ONE 10 AH-6PM
AVERAGE CO LEVEL GREATER THAN 9ppm
FIGURE 6-2. MONITORING SITES USED DURING
THE EPA CARBON MONOXIDE STUDY
-------
This study concluded that the state's permanent monitoring
station on Ninth Street is generally representative of CO
concentrations in downtown Boise, although the station under-
estimated the magnitude and frequency of elevated CO levels.
For example, the permanent station recorded exceedences of
the federal 8-hour CO standard on 47 percent of the study
days. This is in contrast to one or more of the study sites
recording exceedences on 95 percent of the days. The state's
downtown monitoring station recorded an 8-hour CO level of
13.7 ppm at the time that EPA's site 32 station recorded
the 17.2 ppm average noted above. On 19 of the 20 days in
the study at least one of the EPA study sites had a 10:00 a.m.
to 6:00 p.m. average CO level greater than the simultaneous
reading at the state's Ninth Street monitoring station.
Table G-2 summarizes data from this study.
The EPA study confirmed that Boise has a serious CO
problem, and that high CO levels occur at more than a few
isolated locations. As can be seen in Table G-2, peak CO levels
occurred simultaneously at numerous monitoring sites on
December 2, 1977. Twenty-four of the 29 monitoring sites
operating on December 2 recorded 8-hour CO values above the
9 ppm standard, and only two of these stations reported higher
CO levels on any other day of the study.
The EPA study did not, however, fully characterize the
spatial extent of Boise's CO problem. Because all but one
of the monitoring sites were close to roadways, the study
results could not distinguish an "areawide" pattern of high
CO concentrations from a "highway corridor vicinity" pattern.
The EPA study included a limited amount of monitoring
at six indoor locations (4 retail stores, 1 hotel and 1 hos-
pital). Four of the six indoor sites recorded an 8-hour
average CO level greater than 9 ppm. All monitoring loca-
tions at these buildings were sited to avoid the influence
of tobacco smoke. Monitoring was too limited to provide
detailed correlation analysis. In general, however, indoor
CO levels were somewhat less than outdoor levels. Fluc-
tuations in CO levels at several indoor sites generally
paralleled outdoor CO changes. These results are generally
consistent with other studies of indoor vs. outdoor CO
levels (California Air Resources Board 1971; Bellin and
Spengler 1980), although some studies found no difference
between indoor and outdoor CO levels (Yocom et al. 1977)
Idaho Air Quality Bureau Study
In an attempt to better characterize the spatial extent
of the carbon monoxide problem in Boise, the Idaho Air Quality
Bureau conducted a special monitoring program between November 7,
1977 and March 6, 1978. The major purpose of the study was
G-6
-------
Table G-2. Summary of CO Data Collected
During the EPA Study
EPA
Monitoring
Site
Number
1
2
3
4
5
6
7
8
9
10A
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27A
27B
28A
28B
29A
29B
30A
308
31A
3 IB
32A
32B
33A
33B
Number of 8-Hour
CO Values
Exceeding 9.0 ppm
12
0
0
1
3
2
0
1
6
5
8
1
10
1
0
2
3
7
5
7
1
2
3
2
2
1
1
0
0
0
1
0
3
0
C
0
14
1
3
0
Days
of
Data
20
20
20
20
20
18
12
12
17
10
18
17
18
18
15
19
16
19
20
19
20
20
17
20
19
20
10
10
9
9
10
10
10
10
8
8
20
7
6
10
Highest
10 am- 6 pm
CO Value
(ppm)
14.7
9.0
4. 8
9.5
13.5
10.5
8.4
13.0
13.6
15.9
15.6
9.5
14.2
11.2
7.6
9.9
15.2
15.3
12.1
13.8
9.9
11.1
13.0
15.1
13.4
10.6
10.1
5.3
8.0
7. 8
9.5
5.4
11.4
6.0
8.7
6.3
17.2
9.7
11.6
8.4
Date of Highest
CO Value
At EPA Site
12/02/77
11/25/77
11/25/77
12/02/77
12/02/77
12/02/77
11/30/77
11/25/77
12/02/77
12/02/77
12/02/77
12/02/77
12/22/77
11/25/77
12/22/77
12/02/77
12/02/77
12/02/77
12/02/77
12/02/77
12/02777
12/02/77
12/01/77
12/02/77
12/02/77
12/02/77
12/02/77
12/22/77
12/02/77
12/22/77
12/02/7,7
12/12/77
12/02/77
12/14/77
11/28/77
12/22/77
12/22/77
12/12/77
11/30/77
12/14/77
Simultaneous 8-Hour
CO Value (ppm) at
Ninth S-reet Permanent
Monitoring Station
10.5
8. 8
8. 8
10.5
10. 5
10. 5
10.7
8. 3
10.5
10. 5
10. 5
10.5
13. 7
8. 3
13. 7
10. 5
10. 5
10.5
10.5
10.5
10. 5
10. 5
11^
10. 5
10.5
10.5
10. 5
13 . 7
10. 5
13.7
10. 5
5. 2
10.5
4. 0
9. 3
13.7
13. ~
5. 2
10.7
4. 0
NOTES:
NR = no data reported.
Stations designated with an "A" were operated during the first two weeks of the study.
designated with a "B" were operated during the last two weeks of the study.
DATA SOURCE: EPA 1978.
S-ations
G-7
-------
to assess carbon monoxide levels in areas outside the central
business district of Boise. The bench areas southwest of
the Boise River received special attention. Three portable
CO monitors were used to collect data for 1-week time periods
at a total of 46 sites. Traffic counts were made at most
of the monitoring sites. Wind speed and direction data were
collected at a limited number of sites. Monitoring sites
were classified by location as either valley or bench sites,
and by proximity to major roadways as either traffic corridor
or neighborhood sites.
Figure G-3 shows the locations of the 46 monitoring sites.
Despite the limited duration of monitoring at any one site,
20 of the 46 sites recorded at least one 8-hour average CO
value above the 9 ppm standard. Only one of the 12 neighbor-
hood sites reported an 8-hour CO level above the federal
standard, while 19 of 34 traffic corridor stations reported
at least one such episode. Overall, 6 of 25 valley sites
(all traffic corridor stations) and 14 of 21 bench sites
(1 neighborhood and 13 traffic corridor stations) reported
8--hour CO values above the federal standard.
Table G-3 summarizes the monitoring data collecting during
this study. The highest 8-hour CO values were monitored
at traffic corridor sites on the bench. Eight of ten stations
reporting peak 8-hour CO values of 12 ppm or more were bench
sites. The highest 8-hour CO value recorded during the study
(25.0 ppm) occurred on a day when the permanent downtown
monitoring station did not record any violations of the 8-
hour standard. This value also exceeded the peak 8-hour
CO value recorded by the Ninth Street monitoring station
during all of 1978. The only neighborhood site to record
an 8-hour CO value above 9 ppm recorded an 11.1 ppm 8-hour
average at this tir.ie.
The results of the Air Quality Bureau study clearly
indicated that high CO levels occurred near major traffic
arteries on the bench as well as in valley areas. The
results also confirmed the observations of the EPA study
regarding the occurrence of high CO levels even when the
Ninth Street monitoring station shows no violation of the
federal 8-hour standard.
The Air Quality Bureau concluded that ambient CO levels
in the Boise area are a function of both local traffic con-
ditions and areawide meteorological conditions. The in-
fluence of local traffic conditions is illustrated by the
degree to which changes in CO levels parallel changes in
local traffic. Meteorological effects are evident from
instances where CO levels "track" local traffic volumes for
a period of time, then drop to low levels despite increased
traffic flows. Such instances indicate a break-up of a ground
G-8
-------
FIGURE G-3. MONITORING SITES
USED DURING THE IDAHO AIR
QUALITY BUREAU CO STUDY
-LEGEND-
HI BENCH SITE
5) VALLEY SITE
»>oiM2h SITES RECORDING AT LEAST
1 8 HOUR CO VALUE > 9ppm
SOURCE: REDRAWN FROM IDAHO A»R
QUALITY BUREAU,1978
-------
Table G-3. Summary of CO Data Collected During
the 1977-1978 Idaho Air Quality Bureau Study
General
Monitoring
Period J
11-07-77
to
11-14-77
11-17-77
to
11-19-77
11-21-77
to
11-28-77
11-28-77
to
12-05-77
12-05-77
to
12-12-77
12-12-77
to
12-19-77
12-19-77
to
12-27-77
12-26-77
to
01-02-78
01-02-78
to
01-09-78
01-09-78
to
01-16-78
01-16-78
to
01-23-78
01-23-78
to
01-30-78
01-30-78
to
02-06-78
02-06-78
to
02-13-78
02-13-78
to
02-20-78
02-20-78
to
02-27-78
02-27-78
to
03-06-78
Site
*
14
20
47
18
45
5
6
29
27
28
46
25
37
38
11
12
13
15
17
19
32
41
42
2
22
31
8
9
10
16
21
40
3
4
7
35
39
23
34
48
26
30
36
33
43
44
Site
Location
Class2
B
B
B
B
V
V
V
V
V
V
V
V
V
V
B
B
B
B
B
B
V
V
V
V
B
B
V
B
B
B
B
B
V
V
V
B
V
V
B
B
V
V
V
B
V
V
Site
Type3
T
T
T
T
T
T
T
T
T
T
N
T
T
T
T
T
T
T
T
T
N
T
T
N
T
N
T
T
T
T
T
N
N
N
T
T
T
T
N
N
T
N
N
N
T
T
Peak 8-Hour CO Episode
at Monitoring Site
Value
(ppm)
10.
6.
14.
6.
6.
7.
17.
10.
12.
10.
5.
5.
6.
4.
•9.
21.
12.
12.
12.
11.
6.
5.
4.
4.
11.
8.
9.
15.
10.
16.
25.
11.
6.
6.
5.
6.
4.
9.
3.
3.
4.
2.
2.
3.
4.
5.
8
5
6
6
9
5
7
6
2
5
8
6
0
9
9
0
1
0
5
6
3
5
7
6
2
4
1
5
0
8
0
1
1
7
8
7
3
1
3
5
2
4
6
9
1
6
Date
11-10-77
11-10-77
11-12-77
11-17/18-77
11-25-77
11-30-77
11-30-77
12-02-77
12-06-77
12-06-77
12-10/11-77
12-12-77
12-14-77
12-14-77
12-23-77
12-22-77
12-23-77
12-29-77
12-28-77
12-30-77
01-06-78
01-06-78
01-04-78
01-11-78
01-13-78
01-12-78
01-18-78
01-19-78
01-19-78
01-27-78
1-27/28-78
1-27/28-78
02-04-78
02-04-78
02-04-78
02-08-78
02-08-78
02-14-78
02-14-78
02-16-78
2-24/25-78
02-24-78
02-24-78
03-01-78
03-05-78
03-02-78
S:
8-
Lmultane
-Hour CO
:CUS
' (ppra)
Time At Ninth Street
Period Monitorinc Station
1
1
5
9
3
10
5
1
7
10
10
11
7
11
7
4
11
6
7
1
4
7
1
2
4
6
7
3
4
1
6
7
3
6
5
6
7
6
4
6
pm-9
N-8
pin- 9
pm-1
N-8
am- 5
pm-11
am- 6
N-8
N-8
pm-1
pm-9
am- 3
am- 6
am- 6
am- 7
am- 3
am- 7
am- 3
N-8
pm-M
am- 7
am- 2
am- 3
pm-9
am-N
am- 3
pm-9
pm-10
pm-M
pm-2
pm-3
am- 11
pn-M
pm-9
am- 2
am- 3
N-8
pm
cm
cm
am
cm
cm
pm
c-m
pm
era
am
pin
cm
om
pm
cm
pm
pm
pm
pm
pm
pm
^m
pm
pm
pm
pm
am
am
am
pm
pm
pni
P7H
am- 11 am
am- 2
pra-1
am- 2
am- 3
am- 2
pm-M
am- 2
pm
am
pm
cm
pm
pm
9.
-
N3
3.
7.
7.
9.
9.
10.
5.
5.
10.
4.
3.
4.
18.
13.
16.
8.
8.
13.
9.
12.
10.
10.
9.
6.
3.
8.
8.
8.
8.
8.
3.
6.
6.
2.
3.
7.
3.
4.
4.
4.
4.
4.
0.
1.
0
5
3
C
4
5
S
S
- *
S
S
0
—
~~
5
4
e
8
0
6
0*
2
£
i
7*
2
2
5
o*
9*
0
G
0
0
0
3
6
6
• *
2
2
4
T
T
G-10
-------
Table G-3. Cont'd.
NOTES:
NR = No data reported
1 Occasionally one station had a different starting or ending date
2 B - bench site; V - valley bottom site
3 T - traffic corridor station; N - neighborhood station
* Only 7 hours of data, with missing hour treated as 0
DATA SOURCE: Idaho Air Quality Bureau, 1978.
o
i
-------
level temperature inversion. Meteorological influences are
also suggested by instances when CO levels increased during
evening and nighttime hours despite declining traffic volumes
Such events suggest reduced pollutant dispersion accompanying
the formation of ground level temperature inversions. It
is possible, however, that these episodes involve increased
CO emissions from nontraffic sources or pollutant transport
from other locations.
Airport wind data have been compared with wind data
collected at the various monitoring sites. In general, data
from the airport are not representative of wind speeds or
directions at the valley sites. Airport wind direction data
are generally representative of wind directions at the bench
sites. Wind speeds reported at the bench sites were signifi-
cantly lower than wind speeds at the airport.
A comparison of monitored CO levels, available traffic
counts, airport meteorological data, and available monitoring
site meteorological data shows several instances of neighbor-
hood-scale transport of high CO levels. Most such pollu-
tion transport episodes did not, however, result in viola-
tion of the 8-hour CO standard except near other roadway
corridors. Given the limited duration of this study, it
is clear that air masses with high CO levels can be trans-
ported a moderate distance (perhaps 0.5-1 mile) from major
traffic corridors.
This study did not reveal the type of areawide, peak
CO episode shown by the EPA study (on December 2, 1977).
During the 15 weeks when two or three instruments were
operating concurrently, there was only one instance of all
stations reporting their peak CO episode on the same day-
Air Quality Bureau
Monitoring Station Data
The Idaho Air Quality Bureau currently operates two
permanent monitoring stations in Boise. The downtown
station (at the Odd Fellows Hall on Ninth Street, south-
west of Idaho Street) has operated since July 1975. The
Orchard Street station (south of Highway 55) has operated
since May 1978. Monitoring data from these stations are
summarized in Tables G-4 and G-5.
The hourly pattern of CO levels in the downtown area
is illustrated by Figure G-4. Both the morning and evening
commute periods are evident from the monitoring data. The
evening commute period shows a higher average CO value than
the morning commute period. This is partially a reflection
of the station location (near the intersection of two "out-
bound" streets). A more significant factor, however, involves
the operating condition of cars in the local traffic flow.
The evening commute period involves cars which are generally
G-12
-------
Table G-4. Summary of Carbon Monoxide Data From the Boise
Odd Fellows Hall Monitoring Station
(Ambient CO Values in Parts Per
Million By Volume)
Absolute Peak and Second High Values
Monitoring
Period
1975
July
August
September
October
November
December
Annual
1976
January
February
March
April
May
June
July
August
September
October
November
December
Annual
1977
January
February
March
April
May
June
July
August
September
October
November
December
Auuua 1
1-Hour
Peak Value
8.8
16.5
18.5
19.3
28.0
30.5
30.5
35.8
23.3
19.3
18.8
14.5
14.0
14.8
14 .3
20.3
32 .9
32.2
33.7
35.8
25.3
20.3
11.7
8.2
7.6
11.0
15.8
14.2
14 .9
40.9
39.5
25.6
40.9
Second High
6.5
14.0
17.0
15.3
26.8
30.5
30.5
30.8
21.0
18.3
16.8
13.0
12.0
12.5
13. 3
19.0
31 .5
28.4
28. 3
33.7
24.6
19.2
11.7
8.2
7.6
10.7
15.2
13.5
14.6
31.4
24.0
23.0
3'J .5
Peak
4
10
7
10
15
19
19
16
13
9
10
10
9
9
9
12
13
19
18
19
18
12
6
5
4
6
10
11
10
13
15
IB
IB
Nonover lapping
8-Hour Averages
Value
.9
.3
.9
.0
.9
.7
.7
.4
.1
.5
.9
.8
.8
. 1
.2
.3
.7
.7
.3
.7
.0
.4
.7
.8
.6
. 3
. 1
. 2
.7
.9
.1
.4
. 4
Second
4
9
7
7
12
17
17
14
11
8
10
8
8
8
8
10
12
13
16
18
14
11
5
5
4
5
y
10
8
11
11
15
Hi
High
.4
.6
.6
.9
.8
.5
.5
.4
.4
.8
.8
.3
.9
. 7
.6
.8
.4
.4
.9
.3
.9
.9
. 7
.0
.0
. 3
.4
.7
. 2
. 9
.4
.4
.0
Data Sorted for Maximum Number
of 8-Hour Standard Exceedences
ExceecJences
Peak Value
4.9
10.3
7.9
10.0
14.6
15.4
15.4
16.4
11.4
9.5
10.9
10.8
9.8
9. 1
9. 2
9.7
13.7
15.4
16.9
16. 9
17.9
11.9
6.7
5.8
4 . 6
6. 3
10.1
11.2
10. 7
13.9
15.1
17.1
1 7 . y
Second
4
9
7
7
12
15
15
14
10
8
10
8
8
8
8
9
12
13
15
16
13
11
5
5
4
5
9
10
8
11
10
13
17
High
.4
.6
.6
.9
.8
.3
.3
.3
.9
.8
.8
.3
.9
.7
.6
.6
.4
.4
.6
.4
. 4
. 3
.7
.0
.0
.3
.4
.7
. 2
.9
. 7
. 4
. 1
I
0
2
0
1
9
22
34
15
10
1
6
1
1
1
1
5
13
28
34
116
26
9
0
0
0
0
2
3
1
6
13
16
76
Days
0
2
0
1
7
15
25
11
9
1
6
1
1
1
1
4
12
18
22
87
19
8
0
0
0
0
2
3
1
6
11
13
63
Extent of
Data Record
Days
16
31
15
8
25
25
120
29
29
31
30
31
30
31
31
28
23
30
31
354
31
26
31
28
28
24
18
20
29
31
30
31
327
Hours
384
669
311
168
466
527
2,525
611
669
717
680
699
681
643
702
633
494
688
684
7,901
698
569
724
630
606
496
405
449
657
697
683
727
7,341
-------
Table G-4. Conf d.
CD
I
Absolute Peak
Monitoring
Period
1978
January
February
March
April
May
June
July
August
September
October
November
December
Annual
1979
January
February
March
April
May
June
July
August
September
October
November
December
Annual
1980
January
February
March
April
May
June
July
August
September
October
November
Dccr.'inhor
Anmi.i 1
and Second
1-Hour
Peak
23
18
13
17
11
8
6
8
15
26
30
26
30
28
21
12
11
10
13
10
12
13
19
23
30
30
17
18
Value
.8
. 3
.3
.2
.6
.3
.5
.6
.9
.8
.a
.4
.8
.6
.8
.4
. 3
.6
.5
.5
.6
.9
.4
.7
.0
.0
.4
.0
Second
22.
18.
12.
11.
8.
8.
5.
7.
14.
24.
29.
23.
29.
28.
20.
11.
10.
10.
11.
10.
10.
10.
16.
20.
25.
28.
17.
17.
High
0
1
8
5
9
3
8
7
1
4
1
2
1
6
1
9
7
4
7
5
0
4
8
2
9
6
4
1
Peak
15
12
8
7
5
5
4
5
9
11
20
16
20
13
13
8
6
6
8
8
7
6
11
11
17
17
10
11
High Values
Nonover lapping
8-Hour Averages
Value
.9
.8
.9
.9
.1
.2
.4
.9
. 9
. 1
.4
.0
.4
.4
.9
. 1
. 6
.7
.9
.1
.8
.1
.4
.9
.4
.4
. 9
. 2
Second
15
8
7
6
4
5
4
5
9
10
17
13
17
12
11
8
6
6
7
6
7
5
9
11
16
16
9
10
High
. 1
.9
. 3
.2
.8
.0
. 1
.8
.6
.2
.6
. 7
.6
.6
.8
.0
.5
. 4
.1
.8
.4
. 3
.5
.4
.4
.4
.7
.9
Data Sorted for Maximum Number
of 8-IIour Standard Exceedences
Exceedences
Peak
12
10
8
7
5
5
4
5
9
11
17
16
17
12
13
8
6
6
8
8
7
6
11
11
17
17
10
11
Value
.8
. 1
. 9
. 9
.1
.2
.4
. 9
.9
. 1
.6
.0
.6
.6
.9
. 1
.6
. 7
. 9
.1
.8
. 1
.4
.9
.4
.4
. 9
.2
Second
12
9
7
6
4
5
4
5
9
10
15
12
16
11
11
8
6
6
7
6
7
5
9
11
16
16
9
10
High
.1
.2
. 3
.2
.8
.0
.1
.8
.6
.2
.9
.4
.0
.9
.4
.0
.5
.4
.1
.8
. 4
.3
.5
.4
.1
.1
.7
.9
#
16
2
0
0
0
0
0
0
2
5
26
20
71
17
7
0
0
0
0
0
0
0
4
10
16
54
4
4
Days
10
1
0
0
0
0
0
0
2
4
17
16
50
14
5
0
0
0
0
0
0
0
4
7
9
39
4
4
Extent of
Data Record
Days
31
26
31
30
31
30
31
15
30
31
30
31
347
31
28
31
30
31
30
31
31
7
25
30
31
336
31
29
Hours
701
565
709
705
724
568
659
306
686
711
682
705
7,721
698
672
695
596
710
672
699
712
147
584
660
678
7,523
684
648
OATA SOUUCli: Hourly monitoring data from Idaho Air Quality Uuruau.
-------
Table G-5. Summary of Carbon Monoxide Data From the Central
District Health Department Monitoring Station
(Ambient CO Values in Parts Per Million by Volume)
Absolute Peak and Second High Values Data Sorted for Maximum
Monitoring
Period
1978
May
June
July
August
September
October
November
December
Annual
1979
January
February
March
April
May
June
July
August
September
October
November
December
Annual
1980
January
February
March
April
May
Juno
July
Auqust
October
NtiVcMUl'i'l
1-Hour
Peak Value
8
10
10
9
12
18
21
16
21
18
17
16
13
9
9
9
10
18
27
18
29
29
13
15
.7
.7
.5
.7
.7
.2
.3
.5
.3
.7
.2
.5
.8
.3
. 1
.6
.7
.3
.5
.0
.5
.5
.9
.3
Second
8.
8.
10.
9.
12.
16.
17.
16.
18.
17.
17.
16.
9.
8.
8.
9.
9.
16.
20.
17.
24.
27.
13.
13.
High
5
7
5
3
2
3
3
3
2
0
0
2
1
9
6
5
8
9
0
5
2
5
5
3
Number
Nonoverlapping of 8-Hour Standard Exceedences
8-Hour
Peak Value
5
4
5
5
6
9
9
10
10
9
12
6
5
4
5
5
5
8
12
11
12
12
7
7
.0
.6
.6
.8
.7
.5
.5
.4
.4
.5
.1
.7
.1
.8
.7
.1
.6
.7
.6
.8
.8
.8
.1
.4
Averages
Second High Peak Value Second High
5.0
4.6
5.6
5.8
6.7
9.5
9.4 9.5 9.4
10.3 10.4 10.3
10.3 10.4 10.3
9.2 9.5 9.2
10.3 9.1
6.7
5.1
4.8
5.7
5.1
5.6
8.7
12.5 12.6 12.5
11.8 11.8 11.8
12.6 12.8 12.4
12.6 12.8 12.6
7.1
7 .4
Exceedences
#
0
0
0
0
0
1
2
3
6
2
2
0
0
0
0
0
0
0
7
2
7
20
0
0
Days
0
0
0
0
0
1
2
3
6
2
2
0
0
0
0
0
0
0
4
2
5
15
0
0
Extent of
Data Record
Days
22
30
31
23
11
6
30
27
180
31
27
31
30
21
28
31
29
30
31
30
31
350
31
29
Hours
512
705
741
550
256
100
719
611
4,194
692
636
732
717
490
632
688
654
676
696
657
699
7,969
692
C45
Annual
DATA SOURCE: Hourly monitoring data from Idaho Air Quality Bureau.
-------
FIGURE G-4
AVERAGE WINTER CARBON MONOXIDE LEVELS
AT THE BOISE ODD FELLOWS HALL
MONITORING STATION
Q.
Q-
o
o
-------
in a "cold" operating mode (with high emission rates). A
significant portion of the morning commute traffic will be
in a warmed-up operating mode (with lower emission rates).
An interesting contrast to the downtown station is pro-
vided by the Orchard Street station. The pattern of hourly
CO levels at this site (Figure G-5) shows a predominance
of the morning commute pattern. A major factor here, as
at the downtown site, is the cold vs. warmed-up condition
of vehicles in the local traffic flow.
The downtown and Orchard monitoring stations show dis-
tinctive patterns in the occurrence of 8-hour CO values exceeding
the 9 ppm standard. Data from the downtown station are
summarized in Figure G-6. Most episodes occur during time
periods which include the mid-afternoon and early evening
periods. The Orchard site (Figure G-7) shows a pattern
which has two distinct periods of episode conditions. High
CO levels tend to occur during the morning to early after-
noon period and again during the evening to late night time
period. To a large extent, this is probably a reflection
of shopping and other nonwork trips.
The evening and nighttime CO episodes observed at the
Orchard site are also apparent from the special monitoring
program that was conducted by the Idaho Air Quality Bureau.
While traffic sources have been suggested as the major cause
of these episodes/ households using wood stoves or fire-
places are another potential source. Carbon monoxide emissions
from these sources are discussed later in this chapter. With
one exception, the "neighborhood" sites used in the Air Quality
Bureau study did not exceed the 8-hour CO standard. The
one exception appears to be a clear case of CO transport
from major traffic arteries. Thus, there is little evidence
to implicate nonvehicular sources as major contributors to
high CO levels on the bench.
It is also possible that some of the nighttime CO episodes
recorded at the Orchard site are influenced by pollutant
transport from the downtown Boise area. The times of high
CO levels and the distance between the downtown and Orchard
sites are consistent with a slow drift of polluted air to
the bench area. Cold air drainage into the Boise Valley
could provide a mechanism that would lift a polluted but
warmer air mass up to the level of the bench while also
carrying it in a westerly direction.
The pattern of CO episodes at the Orchard site is also
consistent with a localized traffic source combined with
formation of nighttime ground level temperature inversions.
Carbon monoxide transport has seldom been documented over
distances exceeding 1 mile. Monitoring data from the special
G-17
-------
FIGURE G-5
AVERAGE WINTER CARBON MONOXIDE LEVELS
AT THE CENTRAL DISTRICT HEALTH
DEPARTMENT MONITORING STATION
CL.
Q.
O
O
a:
UJ
7.0
6.5H
6.0-i
5.5-1
5.CH
4.5H
4.0H
3.5H
3.0-
2 5H
2.0H
I-5H
0.5H
0.0-
U2 *"- CD <7> — —
I , I I I I I I I '
O
O
O
O
TIME PERIOD
NOTE- BASED ON OCTOBER THROUGH FEBRUARY DATA.
DATA SOURCE'. OCTOBER 1978- FEBRUARY 1980 HOURLY CO DATA
FROM IDAHO AIR QUALITY BUREAU.
G-18
-------
JULY-DECEMBER 1975
181 TOTAL OCCURRENCES
FISURE S-6
TIME PERIODS WITH 8-HOUR CO LEVELS =-9.0 PPM
AT THE BOISE ODD FELLOWS HALL MONITORING STATION
1976
618 TOTAL OCCURRENCES
" •
1977
374 TOTAL OCCURRENCES
8-HOUR TIVE PERIOD
8-HOUR TIME PERIOD
»»*a»a»»»»a«^*ga»aa
8-HOUR TIUE PERIOD
1978
374 TOTAL OCCURRENCES
NOTE- VALUES ABOVE
8-HOUR TIME PERIOD
FREQUENCY GRAPH INDICATE NUMBER OF OCCURRENCES FOR SPECIFIED TIME PERIOD
1979
287 TOTAL OCCURRENCES
8-HOUR TIME PERIOD
1975-1979 COMPOSITE
1,834 TOTAL OCCURRENCES
8-HOUR TIME PERIOD
Oalfl SOUSCE HOU.tLr CO Ofl't FrOM ,OASO Aln ^UAw.Tf PUREiU
-------
FIGURE G-7
TIME PERIODS WITH 8-HOUR CO LEVELS >9.0 PPM
AT CENTRAL DISTRICT HEALTH
DEPARTMENT MONITORING STATION
MAY-DECEMBER 1978
20 OCCURRENCES
1979
92 OCCURRENCES
J - HOUB TIME PERIOD
8-HOUR TIME PERIOD
1978-1979 COMPOSITE
112 OCCURRENCES
6-HOUR HUE PERIOD
SOTE \iLUES aeOvE fREtXJEHCr GRAPH INDICATE NUMBER OF OCCURRENCES
FOR SPECIFIED TIME PERIOD "
DAU SOURCE HDURLT CO DATA FROM IDAHO AIR QUALITY BUREAU
G-20
-------
studies discussed previously do not document CO transport
on this distance scale. The differences in nighttime CO
patterns at the downtown and Orchard Street sites could also
reflect dilution of valley CO concentrations by relatively
clean cold air drainage flows. These light winds could result
in mixing of a polluted air mass in the valley with clean
air flowing down from the Boise Front. At the same time,
the bluff face on the southwest side of the Boise River
could serve to block westerly ground level air flows, shifting
them to the northwest.
Considering all available data and the speculations
discussed above, CO transport from the downtown area to the
bench area must be considered an interesting but unproven
possibility. It is quite likely that both types of drainage
wind influences discussed above occur on some occasions.
Most likely, there is a range of situations from "pure" within-
valley transport and dilution to "pure" valley to bench transport.
Available evidence suggests that the valley-to-bench transport
condition is a rare occurrence.
Idaho Transportation Department
Monitoring Data
The Idaho Transportation Department operates a continuous
CO monitor at its laboratory building off of State Street.
Data have been collected since December 1975. NO statistical
data summaries are available. A preliminary review of the
hourly data indicate five episodes of 8-hour CO levels above i
the federal standard (one in 1976 and four in 1979). The
highest 8-hour CO value appears to be a 10.6 ppm average
on November 16, 1979 (7:00 a.m.-3:00 p.m.). All of these
episodes occurred during the early morning to early afternoon
time period. The highest 1-hour CO level reported was 30
ppm on February 17, 1976 at 8:00 a.m. to 9:00 a.m. The pat-
tern of hourly CO levels strongly suggests the influence
of local vehicle parking activities plus some pollutant trans-
port from other areas.
Summary
Available monitoring data from several sources indicate
that the Boise area experiences a geographically extensive
pattern of high CO levels. These high CO levels are concen-
trated primarily along major traffic corridors. Under appro-
priate meteorological conditions (light winds and low level
temperature inversions), air masses containing high CO levels
can be transported more or less intact over distances of
up to 1 mile. Thus, much of the Boise area is susceptible
to episodes of high CO levels which originate primarily from
major roadway corridors.
G-21
-------
Episodes of high CO levels show a rather strong seasonal
pattern, with most episodes occurring during the winter
(November-February). However, there have been instances
of 8-hour CO levels above the federal standard during every
month of the year and almost every possible 8-hour period
of the day. The seasonality, frequency, and magnitude of
CO episodes show significant yearly variation.
The valley and bench areas in Boise both experience
severe CO episodes. The hourly patterns of high CO episodes
in these two areas are rather distinctive. While these patterns
could be produced in several ways, the simplest explanation
centers around differences in the pattern of vehicle activity.
Vehicle emissions are clearly the source of CO problems in
the Boise area. The frequency and magnitude of CO episodes,
however, is strongly influenced by the meteorological and
topographic conditions of the area.
G-22
-------
BIBLIOGRAPHY
Reference Documents
Bellin, Peter, and John D. Spengler. 1980. Indoor and outdoor
carbon monoxide measurements at an airport. J. Air Pollut.
Control Assoc. 30(4):392-394.
Calif. Air Resources Board. 1971. Outdoor-indoor levels of air
pollutants. ARB no. 4-053-1 (PCA 252). Sacramento. 6 pp. +
appendices.
ESL, Inc., and CH2M Hill. 1974. Ambient air quality measurements
in the Boise, Idaho, urban area. Prepared for Idaho Transnor-
tation Dept. and Ada County Highway District.
Idaho. Air Quality Bureau. 1978. Boise carbon monoxide study,
winter 1977-spring 1978, Boise, Idaho: staff report.
U.S. Environmental Protection Agency. 1978. Carbon monoxide
study, Boise, Idaho, Nov. 25-Dec. 22, 1977, parts 1 and 2.
Prepared by C. B. Wilson and J. W. Schweiss, Surveillance
and Analysis Division, Boise.
Yocom, John E., William A. Cote, and Ferris B. Benson. 1977.
Effects on indoor air quality. Pp.117-155 in Arthur C. Stern,
ed., Air pollution, vol. II. 3rd ed. Academic Press, New
York.
G-23
-------
Appendix H
PROCEDURES USED TO EVALUATE FUTURE AIR
POLLUTION POTENTIAL IN ADA COUNTY
Prepared by:
Jones & Stokes Associates, Inc.
2321 P Street
Sacramento, CA 95816
February 1981
-------
PROCEDURES USED TO EVALUATE FUTURE
AIR POLLUTION POTENTIAL IN ADA COUNTY
The air quality assessment in Chapter 7 of the EIS
used a simple proportionality procedure to evaluate future
air pollution potential and the extent of emission reductions
needed to achieve air quality standards. Observed ambient
air quality is considered to be composed of two components:
a "background" component due to total areawide emissions,
and a highway corridor component due to highway traffic and
nonresidential parking sources. Each community planning
area was treated as a discrete subarea. The following equa-
tions were used in the analysis.
C>T
EL
Rollback amount = CEfy - EL
/CEfv - EL\ f \
Rollback percent = —^= (1001
\ Lhfy / V /
Where:
AQ = ambient air quality
B = background increment contained in ambient air quality
CE = corridor emissions (highway traffic plus on- and
off-street parking sources)
TE = total emissions
EL = emissions limit
S = ambient air quality standards
subscripts: by = base year (1977)
fy = forecast year
H— 1
* GPO 797 - 421 1981
------- |