Preliminary Steps toward Developing a Sound Research Design for Analyzing the Spatial Distribution of Commercial Hazardous Waste Facilities in Wayne

County, Michigan: Part I

March 11, 1998

NRE 501

Robin Saha

General Research Question

Are low income and minority populations disproportionately

exposed to the risks associated with commercial hazardous waste facilities

in Wayne County, Michigan?

Research Design Issues

• Defining geographic areas of impact (“impact zones” or “ host neighborhoods”)

• Selecting a geographic unit of analysis (census tracts versus block groups)

Location of Wayne County, Michigan

STUDY AREA AND TSDF LOCATIONSWayne County, Michigan

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#YI- 94

I- 275

I- 75

US 39

Detroit

TSDFLocation

H u ro n

M o f fe tt

C a n to n

S u m p t e r

R o m u l u s

T a y lo r

H o ll is

V a n B u r e n

D e a rb o r n

W e s t la n dP ly m o u th

G r o s s e Il e

N o rt h v il le

C h a n d le r s

R e d fo r d

T re n t o n

In k s t e r

G r o s s e P o in te

W a y n e

A l l e n P a r k

F la t R o c k

M e r id ia n

S o u th g a t e

L a n g o r

B e ll e v i ll e

R i v e r v ie w

R i v e r R o u g e

R o c k w o o d

H ig h l a n d P a rkH a rp e r W o o d s

#Y

Considerations in Defining Impact Zones (Design Issue #1)• Proximity of known or potential impacts

• Inverse relationship between distance and impact (social, psychological, economic, environmental, and health )

• Size and shape of geographic units for which demographic data are available

• Previous research and comparability with other studies

DESIGN ISSUE #2Considerations in Selecting an Appropriate Unit of Analysis

• How different units affect the delineation of host neighborhoods in terms of how well they approximate circular areas

• Want to create host neighborhoods (“impact zones”) that are as equivalent as possible in size and shape (equidistant from hazardous waste facilities) -- inter-case consistency

Census Tracts with TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit

Census Tracts at Least Partially within 1/2 Mile Circle Centered at TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit

Census Tracts at Least Partially within 1.0 Mile Circle Centered at TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit

1990 Census Tracts Partially within 1.5 Mile Circle Centered at TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit

1990 Census Tracts at least Half within 1.5 Mile Circle Centered at TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit

Number of Census Tracts Partially within and at Least Half within 1.5 Mile Radius of TSDFs

187

110

020406080

100120140160180200

at least 1/2within

partiallywithin

Area in Decimal Degrees of Census Tracts Partially within and at Least Half within

1.5 Mile Radius of TSDFs

0.0400

0.0209

0.0000

0.0050

0.0100

0.0150

0.0200

0.0250

0.0300

0.0350

0.0400

0.0450

at least 1/2 within partially within

Area of Census Tracts Partially within and at Least Half within 1.5 Mile Radius of

TSDFs, as a Percentage of Wayne County

23%

12%

0%

5%

10%

15%

20%

25%

at least 1/2 within partially within

Delineation of Host Neighborhood as Census Tracts Partially Encompassed by Circle of 1.0 Mile Radius

#

Delineation of Host Neighborhood as Census Tracts with Area at Least Half within Circle of 1.0 Mile Radius

#

Census Tracts Partially within 1.5 Mile Circle Centered at Env’l Waste Control

#Y

Census Tract at Least Half within 1.5 Mile Circle Centered at Env’l Waste Control

#Y

Block Groups Partially within 1.5 Mile Circle Centered at Env’l Waste Control

#Y

Block Groups At Least Half within 1.5 Mile Circle Centered at Env’l Waste Control

#Y

Census Tracts Partially within 1.5 Mile Circle Centered at ChemMet

#Y

Block Groups Partially within 1.5 Mile Circle Centered at ChemMet

#Y

Census Tracts At Least Half within 1.5 Mile Circle Centered at ChemMet

#Y

Block Groups At Least Half within 1.5 Mile Circle Centered at ChemMet

#Y

Census Tracts within 1.5 Miles of City Environmental Facility

X

Block Groups within 1.5 Miles of City Environmental Facility

X

“Underlap” and Overlap of Census Tracts within 1.5 Miles of City Environmental

X

“Underlap” and Overlap of Block Groups within 1.5 Miles of City Environmental

X

Area As a Percentage of 1.5 Mile Circle of Underlap and Overlap for City Environmental

Unit ofAnalysis

Underlap Overlap

Tracts 11.9% 8.7%

Block Groups 5.1% 9.3%

Comparison of Host Neighborhood Delineations Using Census Tracts and Block Groups

AREA IN SQUARE MILES

Block Groups Census Tracts

1.5 Mile HostNeighborhood

7.37 6.84

1.5 Mile RadiusCircle

7.07 7.07

% of 1.5 MileRadius Circle

104% 97%

Total Population in Host Neighborhoods Using Tracts vs. Combination of Tracts

and Block Groups

Facility Name

Surrounding Tracts Method (STM)

Fixed Area Method (FAM)

Difference (FAM - STM)

% Diff

Michigan Disposal 4,765 5,637 872 15%Wayne Disposal 4,765 5,637 872 15%

ChemMet 5,050 13,398 8,348 62%Edwards Oil 16,705 17,047 342 2%

Michigan Recovery 17,808 14,996 -2,812 -19%City Envl 29,785 33,428 3,643 11%St. Mary's 32,188 28,384 -3,804 -13%

Petro-Chem 32,854 31,552 -1,302 -4%Envl Waste Control 39,773 28,176 -11,597 -41%

Deerborn 41,884 47,059 5,175 11%Dynecol 42,826 42,008 -818 -2%

Cyanokem 48,878 62,631 13,753 22%Goldshields 63,158 66,064 2,906 4%

TOTAL 375,674 390,380 14,706 4%

AVERAGE 31,306 32,532 1,226 4%

Selected Demographics of Host Neighborhoods Using Tracts vs.

Combination of Tracts and Block GroupsTotal

PopulationPercent

NonwhiteMean Family

Income

Wayne County 2,111,687 43% $40,241

Surrounding Tract Method

375,674 49% $31,920

Fixed Area Method

390,380 43% $31,016

Difference 14,706 -5.9% -$904

% Difference/Ratio

3.8% 0.88 -2.6%

Conclusions Regarding Host Neighborhood Delineations

• Areas within a given radius delineate significantly different host neighborhoods using partially vs. mostly circumscribed geographic units (tracts or block groups)

• Host neighborhood shape and size can (but do not always) vary significantly depending on whether tracts or block groups are used and urban vs. non-urban locations

• Tract/block group differences appear to be insignificant for highly urbanized locations (based on City Env’l TSDF)

• Need to repeat analysis for other host neighborhoods, especially for suburban and rural locations

Conclusions Regarding Units of Analysis

• Preliminary findings suggest choice of using census tracts or block groups can significantly influence demographic results

• These differences need be more carefully assessed before research design decisions regarding most appropriate unit of analysis can be made

• Methods for estimating demographic data in “underlap” and overlap areas may address both research design issues

THE ENDTHE END

STUDY AREA AND TSDF LOCATIONSWayne County, Michigan

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y I- 94

I- 27 5

I- 75

US 39

Detroit

TSDFLocation

H u ro n

M o f fe t t

C a n to n

Su m p te r

R o m u lu s

Ta y lo r

H o l lis

Va n B u re n

D e a rb o rn

W e s t la n dP ly m o ut h

G ro s s e I le

N o rth v il le

C h a n d le rs

R e d fo r d

Tr e n to n

In k s t e r

G ro s s e P o in t e

W a y n e

A l le n P a rk

Fla t R o c k

M e rid ia n

So u th g a te

La n g o r

B e l le v il le

R iv e rv ie w

R iv e r R o u g e

R o c k w oo d

H ig hla n d Pa rkH a rp e r W o o d s

#Y

Area in Square Miles of Underlap and Overlap for City Environmental

Unit ofAnalysis

Underlap Overlap

Tracts 0.8444 0.6143

Block Groups 0.3630 0.6604

Census Tracts at Least Partially within 2.0 Mile Circle Centered at TSDFs

#Y

#Y

#Y#Y #Y

#Y#Y#Y

#Y

#Y#Y

#Y

Huron

Moffett

Canton

Sumpter

Romulus Taylor

Van BurenDearborn

WestlandPlymouth

Grosse Ile

NorthvilleRedford

Inkster

Wayne

Grosse Pointe

Allen Park

Flat Rock

SouthgateBellevilleRiverview

River Rouge

Rockwood

Highland Park

Detroit