Urban Geologic Mapping - Urban Watersheds: Geology, Contamination, and Sustainable Development - page 173

• Methods of investigation
• Sampling collection procedures
• Chain of custody (if required)
• Photographic documentation
• Obtain written permission of private property owner(s) if any type of invasive
fieldwork may be conducted
• Obtain written permission from the local municipality or appropriate governmen-
tal agency if any type of invasive fieldwork has the potential of being conducted
on public property
• Contact local utilities to ensure the proper marking of all utilities in the area where
fieldwork is to be conducted
• Prepare an appropriate written health and safety plan before beginning fieldwork
using the guidelines in Section 4.2.2
Fieldwork may simply consist of digging a test pit with a shovel or drilling a soil boring
by hand using a hand auger. In some cases, test pits may be excavated using a backhoe
or other type of excavator. If you are fortunate, many opportunities exist for conducting
fieldwork without much effort. Areas under construction often offer the urban geologist
ample opportunity to conduct field activities and mapping because the subsurface geology
is already exposed for other purposes. Some of these locations or activities include
• Road building
• Subsurface utility work
• Excavation of foundations for new buildings or for repairing existing buildings
• Demolition activities where the footings and foundation of existing buildings are
excavated and removed
• Sewer repair
• Stormwater control construction activities
Conducting inspections and fieldwork at construction sites provide the geologist with
many opportunities to collect valuable data at a much lower cost, with less effort, and
in a much shorter time. Contact local municipalities to assist fieldwork planning and to
obtain the necessary permissions before construction activities begin. Review the build-
ing permits before the start of construction and contact the appropriate Department of
Transportation and utility company personnel in areas where fieldwork is to be performed.
Then secure the necessary permissions before conducting any activities and employ the
appropriate health and safety measures.
Figures 5.2 through 5.4 document the exposure of the near-surface geology in an urban
area and show the opportunities a construction site offers the geologist. Each example
represents a good opportunity to gather an abundance of geologic information in a short
amount of time and at no cost. Next to each figure is a stratigraphic column used later in
this chapter to assist in building a geologic map and evaluating the recent geologic history
of the region.
After examining the depositional layers from excavation pits as shown in Figure 5.4,
evaluating and recording the strike and dip of the depositional units is required before
a three-dimensional map can be developed (Lahee 1961). Strike refers to the attitude or