Soil Classification and Use
Guidelines
A.
Purpose.
(1) The
purpose of this table is to provide guidance to those who may be considering the
use of land in the Village as a site for the construction of housing or other
structures.
(2) This
guide does not obviate the ultimate necessity of securing approval from the
Tompkins County Department of Health for the use of on-site septic
systems.
(3) This
Appendix is intended to empower the Village to exercise the greater limitations
embodied herein.
B. Map. The soil groups
are comprised of several soil types as identified herein and which soil types
are shown on the map designated as the Tompkins County Soil Map, dated July
1965, and made a part of this regulation. All pertinent
notations, soil mapping unit designators and other information shown upon said
map shall be as much a part of this regulation as if the matter and things set
forth by said map were fully described herein.
C.
Preparation.
(1) The
soil groups and the Tompkins County Soil Map were prepared with the assistance
and cooperation of the USDA Soil Conservation Service,
(2) While
this is considered to be an up-to-date map of standard scale, a soil map is no substitute for on-site
investigation. It must be anticipated that conditions on a specific lot may be
as described, better than described or worse. This applies to soil texture,
drainage and the depth-to-bedrock values.
(3) A soil
map of the Village area is included herein and should be used in conjunction
with the table. The eleven (11) soil groups are described as to characteristics
and use guidelines.
D. Nonrepresentation. The
approval of a subdivision shall not constitute a representation, guarantee or
warranty by the approving authority of the suitability of the land for, or the
practicability or safety of, any structure, use or other plan
proposed.
E.
Utilization.
(1) It is
recognized that the soil maps and the information found in the Tompkins County
Soil Report do not eliminate the need for future on-site investigations. Because
the soil surveys, in which these are based, are confined to the upper thirty-six
(36) inches, all other descriptions (such as depth-to-bedrock, texture and
drainage) are inferred. They are suitable as guidelines but should be checked,
especially near the streams and in the western half of the Village
area.
(2) The
Village Engineer shall have full authority to make additional requirements to
fit conditions that may be observed in the field and/or as a result of
subsequent tests that he might deem necessary, at the expense of the
developer.
(3) Under
use guidelines the intent is to warn those contemplating construction that the
soil conditions are such that more than ordinary precautions in size, design,
layout, etc., may be required for on-site septic systems and
foundation.
(4)
Adequate foundation drains are a necessity to assure dry basements and to
protect homeowners against losses resulting from flooding. Where gravity flow
from the foundation drain(s) is not feasible, sump pumps are
acceptable.
C.
List of soil types.[1]
Soil
Group
Ab
X
ArB
I
BgC
II
DgB
VI
EbB
VIII
EcA
X
Em
X
ErA
VIII
Ha
X
Hc
X
HdA
I
HdB
I
HdC
I
HsB
IV
Soil Types continued on next page.
|
Soil |
Group |
|
HsC3 |
V |
|
HsD3 |
V |
|
HuB |
IV |
|
HwB |
IV |
|
HuB3 |
IV |
|
HuC3 |
V |
|
IcB |
VIII |
|
LaB |
III |
|
LnC |
IX |
|
LoF |
XI |
|
LtB |
IX |
|
LtC |
XI |
|
OaA |
VI |
|
OcC3 |
VII |
|
OrA |
VIII |
|
OrB |
IX |
|
OrC |
IX |
|
PhA |
III |
|
RhA |
VI |
|
RkA |
VI |
|
RkB |
VI |
|
RnC3 |
VII |
|
Ro |
XI |
|
TeA |
VIII |
|
Wm |
X |
|
Ws |
X |
G. Soil
classification.
GROUP I - Well
drained sands and gravel, nearly level through sloping.
(1)
Characteristics. The soils in this group are well drained,
coarse-textured and are formed in glacial outwash plains, terraces and stream
valleys. They are underlain by water deposited beds of sand or sand and gravel.
These soils have moderately rapid to moderate permeability. The seasonal high
water table and bedrock are below six (6) feet. Slope ranges from zero (0)
through fifteen percent (15%). Soils included in this group are: ArB, HdB, HdC
and HdA.
(2) Use
guidelines.
(a) These soils are usually suitable for
on-site septic systems that are adequately designed.
(b) Buildings with and without basements may
be installed on these soils. Some slight problems with cut slope slippage may
occur.
GROUP II - Well
drained coarse silts and loam with a fragipan, gently to
sloping.
(1)
Characteristics. The soils in this group are well drained. The soils are
underlain by loose glacial till and have a fragipan twenty-four to thirty-six
(24 to 36) inches below the soil surface. These soils are moderately permeable
and have a period of very short seasonal wetness. Bedrock is usually six (6)
feet. Slopes range from five percent (5%) to fifteen percent (15%). Soils
included in this group are: BgC.
(2) Use
guidelines.
(a) These soils have moderate limitations for
septic systems and may be used for on-site septic systems that are adequately
designed.
(b) These soils have moderate limitations for
homesites with and without basements and a moderately high bearing capacity.
When buildings with basements are installed below grade (ground line),
foundation drains to a free flowing outlet should be
installed.
(b) Erodibility
on these soils is low.
GROUP III -
Moderately well drained coarse silts and loam with a firm basal till or fragipan layer, nearly
level.
(1)
Characteristics. The soils in this group are moderately well drained with
a seasonal high water table at twelve to twenty-four (12 to 24) inches, and
bedrock usually deeper than six (6) feet. Cuts and excavations deeper than four
(4) feet may encounter an occasional ledge of bedrock. These soils are
moderately permeable in the upper one and one-half to two (11/2 to 2) feet and
slowly permeable below these depths. Slopes range from two percent (2%) to eight
percent (8%). Soils included in this group are: PhA and
LaB.
(2) Use
guidelines.
(a)
These
soils have moderate limitations for septic systems and may be used for on-site
septic systems that are adequately designed.
(b)
These
soils have moderate limitations for homesites with and without basements and a
moderately high bearing capacity. When buildings with basements are installed
below grade (ground line), foundation drains to a free flowing outlet should be
installed.
(c)
Erodibility
on these soils is low.
GROUP IV -
Moderately well drained heavy silts and clays, nearly level to gently
sloping.
(1)
Characteristics. The soils in this group are moderately well drained and
occur in areas where glacial lake sediments have accumulated. These sediments
contain clay and heavy silts. These soils are slowly permeable, and are
susceptible to cut slope slippage. The seasonal high water table is from one and
one-half to three (11/2 to 3) feet. Bedrock is generally below six (6) feet.
Slope ranges from zero (0) to six percent (6%). Soils included in this group
are: HsB, HuB, HuB3 and HwB.
(2) Use
guidelines.
(a) These soils have severe limitations for
septic systems.
(b) Buildings with basements may be installed
on these soils. Adequate foundation drainage to a free flowing outlet should be
provided.
(c) Erodibility on these soils is high, and
erosion may be a problem on all slopes. Final cuts and fills should not be
steeper than four to one (4:1) due to cut slope slippage.
GROUP V -
Moderately well drained, heavy silts and clays, gently sloping to
sloping.
(1)
Characteristics. The soils in this group are well to moderately well
drained and occur in areas where glacial lake sediments have accumulated. These
sediments are in layers composed of silts, very fine sands and clay. These soils
are slowly permeable. The water table ranges from one and one-half to six (11/2
to 6) feet. Cut slope slippage on these soils is severe. Bedrock is generally
below six (6) feet. Slope ranges from six percent (6%) to twenty percent (20%).
Soils included in this group are HuC3, HsC3 and HsD3.
(2) Use
guidelines.
(a) These soils have severe limitations for
septic systems.
(b) Buildings with basements may be installed
on these soils. Adequate foundation drainage to a free flowing outlet should be
provided.
(c) Erodibility on these soils is high, and
erosion may be a problem on all slopes. Final cuts and fills should not be
steeper than four to one (4:1) due to cut slope slippage.
GROUP VI -
Somewhat poorly drained silts, clays and very fine sands that are wet, nearly
level to gently sloping.
(1)
Characteristics. The soils in this group are somewhat poorly drained and
are formed in lake-laid clay and slit. These soils have a moderately low bearing
capacity. Slopes are zero (0) to eight percent (8%). These soils range from very
fine sands through silty clay loam texture. Permeability is slow to very slow.
The seasonal high water table is one-half to one and one-half (1/2 to 11/2)
feet. Bedrock is generally six (6) feet plus. Soils in this group are: DgB, OaA,
RhA, RkA and RkB.
(2) Use
guidelines.
(a) There are very severe limitations for
septic systems on these soils.
(b) These soils have very severe limitations
for homesites with basements due to underground seepage and lack of adequate
outlet for foundation drainage. Wet basements and caving walls are potential
problems.
(c) Erodibility on these soils is high. Final
cuts and fill slopes should be steeper than four to one
(4:1).
GROUP VII -
Somewhat poorly drained silts, clays and very fine sands that are wet and
sloping.
(1)
Characteristics. The soils in this group are somewhat poorly drained and
formed in lake-laid clay and silt and have a clay pan at six to eight (6 to 8)
inches. These soils have a moderately low bearing capacity. Slopes are six
percent (6%) to twelve percent (12%). These soils range from very fine sands
through silty clay loam texture. Permeability is slow to very slow. The seasonal
high water table is one-half to one and one-half (1/2 to 11/2) feet. Bedrock is
generally six (6) feet plus. Soils included in this group are: OcC3 and
RnC3.
(2) Use
guidelines.
(a) There are severe limitations for septic
systems on these soils.
(b) These soils have very severe limitations
for homesites with basements due to underground seepage and lack of adequate
outlet for foundation drainage. Wet basements and caving walls are potential
problems.
(c) Erodibility on these soils is higher than
in Group VI. Final cut and fill slopes should be steeper than four to one
(4:1).
GROUP VIII -
Somewhat poorly, nearly level or gently sloping in glacial
till.
(1)
Characteristics. The soils in this group have a seasonal high water table
at zero (0) to one-half (1/2) foot. These soils are located in flat to gently
undulating landscape. Permeability is very slow. A surface seep condition is
very evident during the wetter periods of the year. Slope ranges from zero (0)
to eight percent (8%). Deep cuts may encounter an occasional ledge of bedrock.
Soils included in this group are: EbB, ErA, IcB, TeA and
OrA.
(2) Use
guidelines.
(a) These soils have severe limitations for
septic systems.
(b) These soils have severe drainage problems
for basements due to surface water seepage into basements. Diverting roof water
and grading fill away from the building is highly
recommended.
[1]
Foundation drains should be installed below footings and vented to a free
flowing outlet. Sump pumps may be needed where free flowing foundation drains
cannot be installed.
GROUP IX - Well
to somewhat poorly drained medium textured materials.
(1)
Characteristics. These soils are in areas where bedrock is within three
or four (3 or 4) feet of the soil surface. Some areas have a slight seasonal
surface wetness. Permeability of the soil material is moderately slow. Some of
the rock can be excavated but blasting may be required, especially in deep cuts.
Soils included in this group are: LnC, LtB, OrB and OrC.
(2) Use
guidelines.
(a) There are severe limitations for septic
systems on these soils due to shallow depth to bedrock.
(b) Depth of bedrock may limit basement
construction.
(c) Erodibility on these soils is low to
medium.
GROUP X - Poorly
drained soils that are subject to ponding and/or flooding, nearly
level.
(1)
Characteristics. These soils are deep, nearly level and generally found
in wet depressions or along drainageways. During the wetter seasons ponding is
common and some areas are subject to flooding. Permeability is moderate though
very slow. Slope ranges are from zero (0) to three percent (3%). Soils included
in this group are: Ab, Ws, Em, EcA, Ha, Hc and Wm.
(2) Use
guidelines.
(a) Generally these soils are too wet to use,
and serve as water retention areas and watercourses. Building in this area is
discouraged.
GROUP XI - Well
drained to moderately well drained medium textured material with bedrock at the
surface or within twenty (20) inches, moderately steep to
steep.
(1)
Characteristics.
Generally these are the soils with slopes in excess of twenty-five percent (25%)
grades. In some areas it is gorge-like. Usually rock is within three or four (3
or 4) feet of the soil surface. Soils included in this group are: LtC, LoF and
Ro.
(2)
Use
guidelines.
(a)
Generally these soils are too steep to
use, and should remain in
their natural cover to prevent excessive erosion. Building in this
area is discouraged.
H. Table of Soils Groups.
The Table of Soils Groups shall be as follows:
Table of Soils
Groups
I.
Well drained sand and gravel 0 to 15%; A, B
(276L-1)
II. Well
drained with fragipan 5 to 15%; A, B (227LF)
III. Moderately
well drained with fragipan or basal till 2 to 8%; A, B
(266FL)
IV. Moderately
well drained silt and clays 0 to 6%; B, C (366FL)
V.
Moderately well drained silt and clays 6 to 20%; D, E
(213LF)
VI. Somewhat
poorly drained silt and clays 0 to 8%; D, E (254LF)
VII. Somewhat poorly drained
silt and clays 6 to 12%; D, F (258LF) VIII.
Somewhat poorly drained in glacial till 0 to 8%; B, C
(208LF)
IX. Well to
somewhat poorly drained over rock 0 to 15%; B, F (299L7F)
X.
Poorly drained, some flooding 0 to 3%; F, G (265LF)
XI. Well to
moderately well drained over rock 0 to 70%; F, G (293LF)
A.
Septic
systems permitted, specific design site investigation
needed.
B.
Buildings
permitted, foundation drains required.
C.
Septic
systems permitted if it can be proven that limitations have been
overcome.
D.
Buildings
not permitted without proof that problems can be solved.
E.
Septic
systems should not be permitted, but in cases where problems are solved, septic
systems may be approved [in most cases, for one (1) lot].
F.
Septic
systems should not be permitted.
G.
Buildings should not be
permitted