Environmental Engineering Reference
In-Depth Information
Preliminary
interpretation
Site
reconnaissance
Final map
preparation
Data collection
Analysis
1. Geologic data
Reports: Geology and groundwater
Maps: Surficial, bedrock, structural,
soil surveys
Review
Program
explorations
2. Soil/rock engineering data
Review
Technical publications, reports from public
agencies, private correspondence, for boring
Prepare preliminary
engineering geology map
Field reconnaissance
of site
Prepare final
engineering geology map
logs, maps, laboratory data
Soil types
Drainage
Rock type/depth
Rock structure
features
Groundwater depth
Hazards identified:
Slides
Sinkholes
Faults
Floodplains
Surface exposures
of soil/rock
Cuts
River banks
Excavations
Quarries/pits
Slopes
Incorporate field
observations and
reanalyze landform
data
3. Terrain analysis data
a. Large area or seismic study:
(1) Topographic maps: 1:100,000;
1:50,000; and 1:25,000
(2) Imagery:
Analysis
LANDSAT 1:1,000,000 and 1:125,000
SLAR 1:125,000
Photos (U-2 or RB-57) 1:125,000
Photos 1:40,000 and 1:20,000
Plot on preliminary
map, make
sketches, take
photos
b. Small area study (nonseismic)
(1) Topographic maps: 1:50,000; 1:25,000
and 1:10,000
(2) Imagery (photos); 1:40,000 or 1:20,000
Program
explorations
Check boundaries
Geologic sections
Samples
In situ
testing
Identify features
for reconnainssance
Hazards, cuts,
quarries, etc.
and 1:10,000
FIGURE 2.1
The elements of the geologic land reconnaissance study.
Geologic hazards
, both regional and local, such as ground subsidence and col-
lapse, slope failures, floods, and lahars.
●
Geologic constraints
, both regional and local, such as expansive soils, weak soils,
shallow rock, groundwater, etc.
●
Information Sources
Geologic
texts provide information on physiography, geomorphology, and geologic forma-
tion types and structures, although usually on a regional basis.
Federal and state agencies
issue professional papers, bulletins, reports, and geologic maps,
as do some cities. Sources of geologic information include the U.S. Geological Survey
(USGS) and the U.S. State geological departments. Agencies for agriculture, mining, and
groundwater also issue reports, bulletins, and maps. Information on the USGS and State
Agencies can be found on the Internet.
Engineering soil surveys
have been prepared for New Jersey (Rogers, 1950) and Rhode Island,
which are presented as reports and maps on a county basis. The maps illustrate shallow soil
and rock conditions and the soils are classified by origin in combination with AASHO
Designation M145-49. The prevailing or average drainage conditions are also shown.
Technical publications
such as the journals of the American Society of Civil Engineers,
Institute of Civil Engineers (London), the Association of Engineering Geologists (USA),
the
Canadian Geotechnical Journal
, and the various international conferences on soil and
rock mechanics, engineering geology, and earthquakes, often contain geologic information
on a specific location.
Climatic data
are obtained from the U.S. Weather Bureau or other meteorological agencies.
Geologic Maps
Geologic maps generally vary in scale from 1:2,500,000 (U.S. map) to various scales used by
state agencies, to USGS quadrangle maps at 1:24,000, and vary in the type of geologic infor-
mation provided. A guide to map scale conversions is given in
Table 2.2.
On a worldwide
basis the availability of geologic maps varies from excellent in modern, developed coun-
tries, to poor to nonexistent in other countries or areas.
