EPA Region 6

TS-PIC-20806003S

September 2008

FRACTURE TRACE ANALYSIS REPORTOF BANDERA ROAD GROUND WATERPLUME SITE

Research and Development

United States

Environmental Protection

Agency

Environmental

Sciences Division

P.O. Box 93478

Las Vegas, NV 89193-3478

LA

Leon Valley/San Antonio, Texas

AROK

TX

NM

TS-PIC-20806003S September 2008

FRACTURE TRACE ANALYSIS REPORT OFBANDERA ROAD GROUND WATER PLUME SITE

Leon Valley/San Antonio, Texas

by

Larry MataEnvironmental ServicesLockheed Martin ServicesLas Vegas, Nevada 89119

Contract No. EP-D-05-088

Work Assignment Manager

J. LinLandscape Ecology BranchEnvironmental Sciences DivisionLas Vegas, Nevada 89193-3478

ENVIRONMENTAL SCIENCES DIVISIONNATIONAL EXPOSURE RESEARCH LABORATORYOFFICE OF RESEARCH AND DEVELOPMENTU.S. ENVIRONMENTAL PROTECTION AGENCYLAS VEGAS, NEVADA 89193-3478

ii

NOTICE

This document has undergone a technical and quality control/assurance

review and has been approved for publication by personnel of the U.S.

Environmental Protection Agency, Office of Research and Development,

Environmental Sciences Division, Landscape Ecology Branch at Las Vegas, Nevada.

It is for internal Agency use and distribution only.

iii

ABSTRACT

This report presents the findings from a historical aerial photographic

fracture trace analysis of a study area that is centered on the Bandera Road

Ground Water Plume site. The study area, comprising the Bandera Road Ground

Water Plume site and the area within an approximate 1.2 kilometers (2 miles)

radius of the site, is located in Leon Valley, Texas, in northwest San Antonio.

Three dates of historical black-and-white aerial photographs were obtained and

analyzed to produce this report. The objective of the fracture trace analysis

was to identify zones of fracturing in the bedrock that could act as

preferential pathways for subsurface contaminant flow. The report provides

operational remote sensing information in support of remedial actions conducted

by the Region 6 Office of the U.S. Environmental Protection Agency (EPA) under

the Comprehensive, Environmental Response, Compensation, and Liability Act

(CERCLA).

Collateral information supplied by the U.S. Environmental Protection

Agency (EPA) indicates that groundwater contamination (volatile organic

compounds) has been detected in drinking water wells on the Bandera Road Ground

Water Plume site. The groundwater from these wells has been used by residents

and businesses in the area.

The fracture trace analysis was performed using black-and-white aerial

photographs acquired in 1945, 1955 and 1959 in conjunction with pertinent

geologic literature. Eight (8) fracture traces were identified proximal on the

study area surrounding the Bandera Road Ground Water Plume site.

The EPA Environmental Sciences Division, Landscape Ecology Branch in Las

Vegas, Nevada, prepared this report for the EPA Region 6 Superfund Division in

Dallas, Texas and the EPA Office of Superfund Remediation Technology Innovation

in Washington, D.C.

v

CONTENTS

Page

Abstract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iii

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Methodology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Fracture Trace Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

FIGURES

Number

1 Site location map, Texas . . . . . . . . . . . . . . . . . . . . . . . . 4

2 Local site location map, Castle Hills, Culebra Hill, Helotes, and San Antonio West, Texas . . . . . . . . . . . . . . . . . . . . . . 5

3 Bandera Road Ground Water Plume site, fracture trace analysis, January 1, 1945 . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

4 Bandera Road Ground Water Plume site, fracture trace analysis, June 2, 2004 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1

INTRODUCTION

This report presents the findings from a fracture trace analysis of the

Bandera Road Ground Water Plume site (CERCLIS ID# TXN000606565) and surrounding

area located in Leon Valley, Bexar County, Texas, in northwest San Antonio

(Figures 1 and 2). Groundwater contamination (volatile organic compounds) has

been detected in drinking water wells on the Bandera Road Ground Water Plume

site. The groundwater from these wells has been used by residents and

businesses in the area (EPA, 2008). The objective of this fracture trace

analysis is to identify zones of fracturing in the bedrock that could act as

preferential pathways for subsurface contaminant flow (see Methodology

Section).

This fracture trace analysis was performed for a study area comprising the

Bandera Road Ground Water Plume site and the area within an approximate 1.2

kilometer (2 miles) radius of the site. This fracture trace analysis report

provides operational remote sensing support for remedial actions conducted by

the Region 6 Office of the U.S. Environmental Protection Agency (EPA) under the

Comprehensive, Environmental Response, Compensation, and Liability Act

(CERCLA).

Since the late 1960s, shortly after the completion of Interstate 410, the

land use/land cover on Bandera Road Ground Water Plume study area has become

increasingly urban. The current land cover/ land use mix includes light

industrial, commercial, and residential. The urban development has destroyed

or obscured the natural landscape as well as any possible fracture trace

photographic signatures visible on the study area. Therefore this fracture

trace analysis is based on the analysis of aerial photographs taken before

urban development occurred in the study area. Black-and-white aerial

photographs taken in 1945, 1955, and 1959 in conjunction with pertinent

geologic literature (see References) of the Bandera Road Ground Water Plume

site and surrounding area were used to produce this report.

3

Eight (8) fracture traces were identified on the Bandera Road Ground Water

Plume study area. The locations of the fracture traces are presented on two

figures in this hard copy report. An overlay containing the fracture traces

has been placed atop a 1945 aerial photographic print (Figure 3) in order to

display the findings as they appeared prior to urban development of the study

area. A second figure (Figure 4), using the same overlay but placed atop 2004

aerial photography, depicts where the fracture traces are situated in the

current urbanized landscape. In addition, the fracture trace analysis results

are also presented in a digital compact disk (CD) format which has been

inserted in an envelope in the back of the report.

Sources for all maps, aerial photographs, and collateral data used in the

production of this report are listed in the References section. A list of all

aerial photographs that were identified and evaluated for potential application

to this study can be obtained by contacting the EPA Work Assignment Manager.

Historical aerial photographs used in the analysis of this site have been

digitally scanned and printed for use in this report. A transparent overlay

with interpretative data is affixed to each of the digital prints. See the

Methodology section for a discussion of the scanning and printing procedures.

The EPA Environmental Sciences Division, Landscape Ecology Branch in Las

Vegas, Nevada, prepared this report for the EPA Region 6 Superfund Division in

Dallas, Texas and the EPA Office of Superfund Remediation Technology Innovation

in Washington, D.C.

4

Figure 1. Site location map, Texas (USGS, 1972). Approximate scale 1:5,200,000.

UNITED STATES

(1972)

BANDERA ROADGROUND WATER

PLUME SITE

5

Figure 2. Local site location map, Castle Hills, TX (USGS, 1992), Culebra Hill, TX (USGS, 1993), Helotes, TX (USGS, 1992), and San Antonio West, TX (USGS, 1993). Approximate scale 1:24,000.

BANDERA ROAD GROUNDWATER PLUME SITE

CASTLE HILLS, TX

(1992)

CULEBRA HILL, TX

(1993)

HELOTES, TX

(1992)

SAN ANTONIO WEST, TX

(1993)

098o37'30"W

29o30'00"N

29o29'47"N,098

o37'12"W

(NAD 83)

6

METHODOLOGY

This report was prepared using a standard methodology that includes the

following steps:

• data identification and acquisition,

• photographic analysis and interpretation, and

• graphics and text preparation.

These steps are described below. Subsections also address details related

to specific kinds of analyses that may be required to identify environmental

features such as surface drainage and wetlands. All operational steps and

processes used to perform this work (including data identification and

acquisition, photographic analysis and interpretation, and graphics and text

preparation) adhere to strict QA/QC guidelines and standard operating

procedures (SOPs). These guidelines and procedures are documented in the

Master Quality Assurance Project Plan (QAPP) prepared for Remote Sensing

Support Services Contract No. EP-D-05-088 (LMS, 2006).

Data identification and acquisition included a search of government and

commercial sources of historical aerial film for the study area. Photographs

with optimal spatial and temporal resolution and image quality were identified

for acquisition. In addition, U.S. Geological Survey (USGS) topographic maps

were obtained to show the study area location and to provide geographic and

topographic context.

To conduct this analysis, the analyst examined diapositives

(transparencies) of historical aerial photographs showing the study area.

Diapositives are most often used for analysis instead of prints because the

diapositives have superior photographic resolution. They show minute details

of significant environmental features that may not be discernible on a paper

print.

A photographic analyst uses a stereoscope to view adjacent, overlapping

pairs of diapositives on a backlit light table. In most cases, the stereoscope

7

is capable of various magnifications up to 60 power. Stereoscopic viewing

involves using the principle of parallax (observing a feature from slightly

different positions) to observe a three-dimensional representation of the area

of interest. The stereoscope enhances the photo interpretation process by

allowing the analyst to observe vertical as well as horizontal spatial

relationships of natural and cultural features.

The process of photographic analysis involves the visual examination and

comparison of many components of the photographic image. These components

include shadow, tone, color, texture, shape, size, pattern, and landscape

context of individual elements of a photograph. The photo analyst identifies

objects, features, and "signatures" associated with specific environmental

conditions or events. The term "signature" refers to a combination of

components or characteristics that indicate a specific object, condition, or

pattern of environmental significance. The academic and professional training,

photo interpretation experience gained through repetitive observations of

similar features or activities, and deductive logic of the analyst as well as

background information from collateral sources (e.g., site maps, geologic

reports, soil surveys) are critical factors employed in the photographic

analysis.

The analyst records the results of the analysis by using a standard set of

annotations and terminology to identify objects and features observed on the

diapositives. Significant findings are annotated on overlays attached to the

photographic or computer-reproduced prints in the report and discussed in the

accompanying text. Annotations that are self-explanatory may not be discussed

in the text. The annotations are defined in the legend that accompanies each

print and in the text when first used.

Objects and features are identified in the graphics and text according to

the analyst's degree of confidence in the evidence. A distinction is made

between certain, probable, and possible identifications. When the analyst

believes the identification is unmistakable (certain), no qualifier is used.

Probable is used when a limited number of discernible characteristics allow the

analyst to be reasonably sure of a particular identification. Possible is used

when only a few characteristics are discernible, and the analyst can only infer

an identification.

8

The prints in this report have been reproduced, either by photographic or

computer methods, from the original film. Reproductions are made from the

original film and may be either contact (the same size) prints or enlargements,

depending on the scale of the original film. Any computer-produced prints used

in this report are generated from scans of the film at approximately 1,300 dots

per inch (dpi) and printed at 720 dpi. Although the reproductions allow

effective display of the interpretive annotations, they may have less

photographic resolution than the original film. Therefore, some of the objects

and features identified in the original image and described in the text may not

be as clearly discernible on the prints in this report.

Study area boundaries shown in this report were determined from aerial

photographs and from information supplied by EPA Region. Boundaries used in

this report do not necessarily denote legal property lines or ownership.

Fracture Trace Analysis

Fracture trace analysis is the technique for locating fractures traces or

geologic lineaments on the earth’s surface. Photographic signatures such as

soil-tonal variations, and vegetational and topographic alignments are

identified, analyzed, and compared to known cultural and geologic information

to determine if the signatures are likely to be expressions of fractures in the

bedrock. Results from the fracture trace analysis are presented on clear

acetate overlays to photographs or USGS topographic maps.

9

FRACTURE TRACE ANALYSIS

A fracture trace analysis of the Bandera Road Ground Water Plume study

area was performed using historical aerial photographs. Identified fracture

traces were compiled onto both aerial photographic prints as well as into a

geographic information system (GIS) file. Fracture trace analysis is the

technique of using aerial imagery for locating fracture traces or geologic

lineaments on the earth’s surface based on the photo-geologic signatures such

as soil-tonal variations and vegetational and topographic alignments. Fracture

traces are considered to be the surface expressions of vertical-to-near-

vertical zones of fracture concentration in bedrock (see Methodology section).

The fracture trace study area analyzed for this report covers an

approximate 32.5 square kilometer (12.5 square mile) area, centered on the

Bandera Road Ground Water Plume site located in Bexar County, Texas. The study

area lies within the Balcones Fault Zone and the bedrock geology underlying the

study area (Cretaceous-Age sedimentary rocks, e.g., limestone, clay, and chalk)

have been displaced by a series of en echelon and normal faults. The site

itself is situated between two minor faults that may partially impede

perpendicular ground water flow, and therefore groundwater contamination flow,

from away from the site (EPA, 2008).

The fracture trace analysis was conducted using 1955 and 1959 (1:20,000)

large-scale photographs, 1945 (1:36,000) medium-scale photographs, and geologic

literature describing the area. Eight (8) fracture traces were identified

during the course of the analysis. The fracture traces are presented on an

overlay to a print produced from the 1945 aerial photography (Figure 3) and

also onto an overlay to the 2004 aerial photography (Figure 4). The 1945

photographic print depicts the study area prior to urban development had

occurred while the 2004 photograph more closely depicts current conditions on

the study area.

10

All of the eight fracture traces identified in this fracture trace

analysis fall within the study area; however, none of the traces actually fall

within the Bandera Road Ground Water Plume site itself. One fracture trace,

located to southeast of the site (see Figures 3 and 4), terminates close to the

east side of the site. Fracture traces that intersect the two minor faults,

which are situated around the site and that may restrict groundwater

contamination flow from the site (EPA, 2008), could provide infiltration

pathways for contaminants to flow across the faults.

In addition to the fracture trace analysis presented in this hard copy

report, results from the analysis are also presented in a GIS format on the

digital compact disk (CD) which has been inserted in an envelope in the back of

the report.

11

Figure 3. Bandera Road Ground Water Plume site, fracture trace analysis, January 1, 1945. Approximate scale 1:23,080.

BANDERA ROADGROUND WATER

PLUME SITE

Leo

n C

reek

HUEBNER R

OAD

BA

ND

ER

A R

OA

D

GRISSOM ROAD

13

Figure 4. Bandera Road Ground Water Plume site, fracture trace analysis, June 2, 2004. Approximate scale 1:22,750.

BANDERA ROADGROUND WATER

PLUME SITE

Leo

n C

reek

HUEBNER R

OAD

BA

ND

ER

A R

OA

D

GRISSOM ROAD

I-410

15

REFERENCES

MAPS

Sourcea Figure Name Scale Date

USGS 1 United States 1:2,500,000 1972 USGS 2 Castle Hills, TX 1:24,000 1992 USGS 2 Culebra Hill, TX 1:24,000 1993 USGS 2 Helotes, TX 1:24,000 1992 USGS 2 San Antonio West, TX 1:24,000 1993

COLLATERAL INFORMATION

EPA. 2008. Collateral data and site map supplied by EPA Region 6 as attachment to Remote Sensing Services Request Form. LMS (Lockheed Martin Services). 2006. Master Quality Assurance Project Plan. Prepared for EPA Environmental Sciences Division. Contract EP-D-05-088. Las Vegas, Nevada.

AERIAL PHOTOGRAPHS

Photo Date of Original Film Mission Source EPIC sourcea Figureb acquisition scale typec I.D. frame # ID #

AVPT 3 01-01-45 1:36,000 B&W 290 46, 47 141482,141483 USGS - 05-14-55 1:20,000 B&W BQQ-2P 117-119 141509-141511 USGS - 10-23-59 1:20,000 B&W BQQ 38-40 141524-141526 USDA 4 06-02-04 1:40,000 CIR NAIP D299836_1 DOQQ

D299835_2 DOQQD299827_4 DOQQD299828_3 DOQQ

aAVPT Aerial Viewpoint, Inc., Spring, Texas USDA U.S. Department of Agriculture, Salt Lake City, Utah USGS U.S. Department of Interior, U.S. Geological Survey, Washington, D.C.bPhotographs listed with no figure number were analyzed but not placed in this report.cB&W Black-and-white CIR Color infrared