When
required, a Geotechnical engineering report shall be prepared by a
professional engineering firm under the direction of an Ohio registered
Geotechnical Engineer.
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| A. |
Geological
information in the report (s) shall be as follows:
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1. |
Review of generally accepted
previously published geologic reports pertaining to the area. |
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2. |
An adequate
description of the geology. |
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3. |
Identification of active and
dormant landslides based on both site analysis and published geologic maps. |
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4. |
Discussion of
geomorphology and relevant hill slope and stream processes |
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5. |
Description and
evaluation of offsite geologic hazards that may affect the graded site.
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These studies
shall be performed for the entire parcel, and shall not be limited only to
those portions to be graded.
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B. |
Geotechnical
reports shall include the following
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1. |
Subsurface
exploration and testing sufficient to represent conditions of the Entire
parcel. At a minimum all reports should address the following:
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| |
|
a. |
Description of the soil or
bedrock encountered |
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|
b. |
The in situ dry density and
moisture content of each soil or bedrock unit |
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c. |
Presence and depth of
groundwater encountered |
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d. |
Analysis and recommendations
appropriate to the project, consistent with these guidelines
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2. |
Laboratory tests
should include the following as appropriate
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|
a. |
Classification tests,
using the Unified Soil Classification System. These consist of sieve
analysis and plasticity testing. |
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b. |
Strength tests.
Either triaxial or direct shear
tests may be used. Saturated, drained tests should be used for evaluating
long-term problems, such as slope stability. |
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|
c. |
Consolidation tests,
if loads are to be placed upon clay soils. |
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d. |
Compaction tests
performed in accordance with
ASTM standards for soils to be used in engineered fills or backfills of
retaining walls.
|
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3. |
Analysis of
areas to be graded.
|
| |
|
a. |
Field and laboratory tests
of the land to be covered with fill, to determine bearing value of the land
and consolidation potential. |
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b. |
Field and laboratory soil
analysis of the material proposed for the fill, including its source and
expansive quality and statement as to its suitability. The analysis shall
also specify the maximum density and optimum moisture content in accordance
with ASTM standards. |
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c. |
Field and laboratory soil
analysis of existing soil conditions in the proposed cut locations. Sampling
and testing shall be sufficient to evaluate the stability of cut slopes, and
should include strength testing of saturated soil materials and evaluation
of bedrock jointing and weathering processes. Quantitative stability
analyses generally should be performed for any proposed slopes steeper than
3:1. |
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d. |
Field and laboratory
analysis of all identified active and dormant landslides as well as
significant bodies of colluvium on and immediately adjacent to the parcel.
Sampling and testing shall be sufficient to evaluate saturated strength of
materials, depth to slide surface, potential for future movement, and risks
to proposed structures or roadways. The evaluation should include a
numerical slope stability analysis.
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4. |
Groundwater
levels and evaluation of any potential ground water condition that may
affect soil strength, consolidation, and slopes stability.
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5. |
Groundwater
levels and evaluation of any potential ground water condition that may
affect soil strength, consolidation, and slopes stability.
|
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6. |
Professional conclusions and
recommendations for grading and foundations as appropriate to the site,
including:
|
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|
a. |
Foundation type and
capacity. |
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b. |
Short and long-term
settlement potential, including expected magnitude of settlement and time
variation. |
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c. |
Mitigation measures for
expansive soils. |
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d. |
Lateral loads (passive,
active, at rest) for current and proposed site conditions. |
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e. |
Slope stability. This should
include site-specific specifications for any proposed repairs. |
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f. |
Shrinkage or settlement of
engineered fills. |
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g. |
The maximum acceptable
stable slope inclinations for proposed cut and fill slopes, assuming
adequate terracing, drainage, and erosion control planting. |
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h. |
Surface and subsurface
drainage necessary to ensure long-term stability of cut slopes and bodies of
fill.
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7. |
A complete and
detailed specification for clearing, grubbing, and all aspects of grading,
including utility trench backfill and retaining wall backfill, with special
emphasis on the depth of fill layers, benching into native materials,
preparation of areas to receive fill, compaction methods, moisture content,
frequency of field density tests, and minimum density to be obtained in the
field as related to laboratory tests. |
