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SALT LAKE CITY ORDINANCE
No. 10 of 2001
(Amending Chapter 18.28 of the Site Development Ordinance,
Adopted by Reference in Section 18.28.010 of the Salt Lake City Code,
Regarding Slope Evaluation and Interpretation Standards)
AN ORDINANCE AMENDING CHAPTER 18.28 OF THE SITE DEVELOPMENT
ORDINANCE, ADOPTED BY REFERENCE IN SECTION 18.28.010 OF THE SALT LAKE
CITY CODE, REGARDING SLOPE EVALUATION AND INTERPRETATION
STANDARDS, PURSUANT TO PETITION NO. 400-99-52.
WHEREAS, on August 18, 1981, in Bill No. 61 of 1981, the Salt Lake City Council first
adopted Site Development Regulations for the City in order to protect the general health, safety
and welfare, and to promote the continued orderly growth of the City; and
WHEREAS, said ordinance established, among other things, limitations on development
of slopes that are steeper than 40%; and
WHEREAS, on November 1, 1994, in Ordinance No. 98 of 1994, the Salt Lake City
Council amended certain provisions of the Site Development Ordinance after finding that the
amendments were in the best interest of the City in developing its foothill areas and that the
amendments properly balanced private property rights with legitimate City concerns regarding
slope stability, fire protection, aesthetics, traffic, drainage and flood protection; and
WHEREAS, one of the amendments in Ordinance No. 98 of 1994 changed the
development limitation for slopes from 40% to 30% after research showed that landslides,
surficial slope instability, slope failure, and soil erosion threats significantly decreased on slopes
which are 30% or less; and
WHEREAS, between the time the Site Development Ordinance was first adopted and the
present, administrative rules and interpretations have been developed to help guide the Planning
Commission in evaluating significant steep slopes in foothill developments and in establishing
development limit boundaries; and
WHEREAS, on September 7, 1999, the City Council asked that the administrative rules
and interpretations be codified as part of the Site Development Ordinance.
NOW THEREFORE, be it ordained by the City Council of Salt Lake City, Utah:
SECTION 1. Section 18.28.20.A 16-45 of the Site Development Ordinance, adopted by
reference in Salt Lake City Code Section 18.28.010, shall be and hereby is amended to read as
follows:
16. Development Limit Line means a legally described line, determined by the Planning
Commission and shown on the final subdivision plat, which defines the boundary
between developable and undevelopable areas. In those portions of the plat designated as
undevelopable, grading, landscaping, construction activities, and other disturbances of
the land are prohibited.
17. Driveway means a way or route for use by a vehicle traffic leading from a parking area
or from a house, garage, or other structure, to a road or street.
18. Earth Material means any rock, natural soil, or any combination thereof
19. Engineering Geologist means graduate in geology or engineering geology of an
accredited university, with five or more full years of professional post graduate
experience in the application of the geological sciences, of which three full years shall be
in the field of engineering geology that has required the application of geological data,
techniques, and principles to engineering problems dealing with ground water, naturally
occurring rock and soil, and geologic hazards for the purpose of assuring that geological
factors are recognized and adequately interpreted and presented.
20. Erosion means the wearing away of the ground surface as a result of the movement of
wind, water, and/or ice.
21. Excavation means any act by which vegetation, earth, sand, gravel, rock, or any other
similar material is cut into, dug, quarried, uncovered, removed, displaced, relocated, or
bulldozed, and shall include the conditions resulting therefrom.
22. Existing Grade means the actual elevation (in relation to mean sea level) of the ground
surface before excavation or filling.
23. Fill means any earth, sand, gravel, rock, or any other material which is deposited, placed,
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replaced, pushed, dumped, pulled, transported, or moved by man to a new location and
shall include the conditions resulting therefrom.
24. Fill Material means earth material free from rock or similar irreducible material
exceeding 12 inches in diameter, metal, and organic material except that topsoil spread
on cut and fill surfaces may incorporate humus for desirable moisture retention
properties.
25. Fuel Break means a strategically located strip or block of land, varying in width, on
which vegetation has been modified to provide a safer place for firefighters to work and
to help reduce the rate of fire spread.
26. Grading means excavation or fill or any combination thereof and shall include the
conditions resulting from any excavation or fill.
27. Insignificant Steep Slope means an area of 30% or greater slope which is located
within a larger area of slope which is less than 30% as determined by ten-foot averaging.
28. Level Building Site means a site contained wholly within the buildable area, of a
dimension not less than 30 feet by 40 feet, to accommodate the main structure, required
off-street parking, and drainage resulting from said improvements. Slope of the Level
Building Site shall not exceed 16 percent.
29. Licensed Architect means an architect who is registered with the Department of
Registration of the State of Utah.
30. Natural Drainage means water which flows by gravity in channels formed by the
surface topography of the earth prior to changes made by the efforts of man.
31. One Street Access means a street that provides the sole access to one or more other
streets.
32. Parcel means all contiguous land in one ownership, provided, however, each lot
conforming to the Zoning Ordinances of Salt Lake City in a subdivision may be
considered to be a separate parcel.
33. Percent of Slope means the slope of a designated area of land determined by dividing the
horizontal run of the slope into the vertical rise of the same slope, measured between
contour lines on the referenced contour map and converting the resulting figure into a
percentage value.. This calculation is described by the following formula:
S = v/}I where "S" is the percent of slope;
"V" is the vertical distance; and
"H" is the horizontal distance.
34. Permittee means any person to which a site development permit has been issued.
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35. Person means any person, firm or corporation (either public or private), the State of Utah
and its agencies or political subdivisions, the United States of America and its agencies
and instrumentalities, and any agent, servant, office, or employee of any of the foregoing.
36. Planning Director means the Planning Director of Salt Lake City.
37. Quarry means an open excavation for the extraction of resources.
38. Registered Professional Engineer means a civil engineer who is registered with the
Department of Registration of the State of Utah.
39. Removal means killing vegetation by spraying, complete extraction, or excavation, or
cutting vegetation to the ground, trunks, or stumps.
40. Seismic means characteristic of, or produced by, earthquakes or earth vibration.
41. Significant Steep Slope means an area of 30% or greater slope, as determined
using ten-foot averaging, which is intended to be protected from development or other
disturbance.
42. Site means a lot or parcel of land, or a contiguous combination thereof, where grading
work is performed as a single unified operation.
43. Site Development means altering terrain and/or vegetation.
44. Slope Classification Map means a map prepared as a colored exhibit by a registered
professional engineer or land surveyor based upon a contour map of the specified scale
and contour interval, upon which the measured and calculated percent of slope (measured
between every contour interval on the map) is classified or grouped into percentage of
slope data in ten percent slope groupings as follows:
Slope Classification Percent Of Slope Mapped Color
Level 0 - 9.9% Uncolored
Slight 10 - 19.9% Yellow
Moderate 20 - 29.9 % Orange
Severe 30% and greater Red
45. Soils Engineer means a registered civil engineer of the State of Utah, specializing in soil
mechanics and foundation engineering, familiar with the application of principles of soil
mechanics in the investigation and analysis of the engineering properties of earth
materials.
SECTION 2. Section 18.28.20.A 46-50 of the Site Development Ordinance, adopted by
reference in Salt Lake City Code Section 18.28.010, shall be and hereby is enacted to read as
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follows:
46. Special Natural Topographic Feature means a naturally occurring feature which is
determined to be unique among similar features of its kind (i.e., rock formation, water
feature) or has historical associations (e.g. Ensign Peak).
47. Surcharge means the temporary placement of fill material on a site in order to compress
or compact the natural soil mass.
48. Ten-foot Averaging means calculating the percent of slope (see definition
18.28.20.A.33. above) between 10 foot elevation intervals (elevations ending in "0", e.g.
4720 to 4730, 4730 to 4740, etc.) on an accurate Slope Classification Map. This
technique is used to determine areas of significant steep slope, insignificant steep slope,
and to establish development limit lines.
49. Testing Laboratory means a testing laboratory that requires supervisory personnel to be
professional engineers registered with the Department of Registration of the State of
Utah.
50. Vacant means land on which there are no structures or only structures which are
secondary to the use or maintenance of the land itself.
SECTION 3. Section 18.28.30.B.11 of the Site Development Ordinance, adopted by
reference in Salt Lake City Code Section 18.28.010, shall be and hereby is amended to read
as follows:
11. Developable Area Limitation.
a. The Planning Commission shall review each proposed foothill subdivision and, using
"ten-foot averaging", shall determine the extent of significant steep slopes within the
subdivision. The Planning Commission shall require all such undevelopable portions
of proposed subdivisions to be identified by placement of a development limit line
and legal description upon the final plat. Such limitation shall also be made a part of
the subdivision restrictive covenants. In addition to protecting significant steep
slopes, development limit lines may also be established to protect natural vegetation,
special natural topographic features, faults, or unique views.
b. Significant steep slopes identified by development limit lines on a subdivision plat
shall be designated as undevelopable area. Said slopes if retained within the
subdivision, shall be designated and maintained as common area and shall be
protected from subsequent alteration or encroachment by a vegetation and open space
preservation easement granted to Salt Lake City by dedication on the subdivision plat.
In no event shall roads traverse such slopes.
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c. Undevelopable area shall not be used to determine the minimum lot size as required
by the underlying zone, unless specifically approved by the Planning Commission
through the planned development review process.
d. Once established on the subdivision plat, the development limit line shall be
delineated on all building permit site plans and shall be staked in the field prior to
construction on any lot affected by the development limit line.
SECTION 4. Section 18.28.30.D.3 of the Site Development Ordinance, adopted by
reference in Salt Lake City Code Section 18.28.010, shall be and hereby is amended to read as
follows:
3. Determination of Developable and Undevelopable Slopes.
a. Undevelopable Slopes. Significant steep slopes identified on a Slope Classification Map
shall be designated undevelopable area. Said slopes, if retained within the subdivision,
may be designated and maintained as common area. In no event shall streets traverse
such slopes.
b. Slopes Altered From Their Natural Condition. The following standards shall be used
in determining whether or not altered slopes are developable:
i. Slopes Altered Prior to August 18, 1981.
A. Roads and driveways. Roads and driveways established prior to August 18,
1981 which traverse significant steep slopes may remain but shall not be widened
or re-graded in order to meet minimum standards for primary access to new
development. Existing roads and driveways established prior to August 18, 1981,
which cross slopes less than 30% may be re-graded and widened if necessary.
Re-grading shall not create new areas of slope over 30%.
B. Buildable Areas.
(1).Lots shown on any subdivision plat recorded prior to August 18, 1981, shall
be considered legal building lots subject to current zoning requirements.
(2).Sites altered from their natural condition prior to August 18, 1981, that meet
the current standard to qualify as buildable area (less than 30% slope), may be
approved as building sites if driveway or street access to such sites, which also
meet current development standards, are available or can be provided. Sites
that are isolated within areas of significant steep slopes shall not be considered
buildable areas.
ii. Slopes Altered Between August 18, 1981 and November 1, 1994.
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A. Roads and driveways. Roads and driveways that were legally constructed
between August 18, 1981, and November 1, 1994, which traverse slopes up to but
not exceeding 40% may be used as access to new development but shall not be
widened or re-graded in order to meet minimum standards for primary access for
such development. Existing roads and driveways established between August 18,
1981 and November 1, 1994, which cross slopes less than 30% may be re-graded
and widened if necessary. Re-grading shall not create new areas of slope over
30%. Roads or driveways which were established without first obtaining a permit
from the City shall be restored to the original grade and revegetated.
B. Buildable Areas. Lots shown on any subdivision plat recorded between August
18, 1981, and November 1, 1994, on which slopes up to 40% were designated as
buildable areas shall be considered legal nonconforming lots but are subject to
current zoning requirements. Illegal grading which occurred after August 18,
1981, and created slopes less than 40% on natural slopes which were originally
greater than 40%, shall not be considered as buildable area, shall be restored to
the original grade, and shall be revegetated.
iii. Slopes Altered After November 1, 1994.
A. Roads and driveways. Roads and driveways that were legally constructed after
November 1, 1994, may be used as access to new development. Roads or
driveways which were established without first obtaining a permit from the City
shall be restored to the original grade and revegetated.
B. Buildable Areas. Illegal grading occurring after November 1, 1994, which
created slopes less than 30% on natural slopes which were originally greater than
30%, shall not be considered as buildable area, shall be restored to the original
grade, and shall be revegetated.
iv. Slopes Altered Prior to Annexation of Property to Salt Lake City.
A. Roads and driveways. Roads and driveways which were legally constructed and
designated for public use prior to the effective date of this ordinance which are
located on property that is subsequently annexed to Salt Lake City may be used as
access to new development. However, if such roads cross areas of significant
steep slope, they shall not be widened or re-graded in order to meet minimum
City standards.
B. Buildable Areas. Lots shown on any subdivision plat recorded prior to the
effective date of this ordinance and subsequently annexed to Salt Lake City shall
be considered legal building lots but are subject to current zoning requirements.
Illegal grading which created slopes less than 30% on natural slopes which were
originally greater than 30%, shall not be considered as buildable area, shall be
restored to the original grade, and shall be revegetated.
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v. Verifying Limits of Disturbance. If the City and developer cannot agree on the
limits of man-made slope disturbance, the developer shall be responsible for
providing a geotechnical evaluation sufficient to establish such limits of disturbance.
vi. Verifying Date of Disturbance. The date of slope disturbance shall be established
based on the best available information. This may include, among other things,
evaluation of historic aerial photography, surveys, or development plans for adjacent
properties.
vii. Burden of Proof. It shall be the responsibility of the owner/petitioner to provide
documentation and other evidence to verify the original and current slope of a site,
the date and extent of any site disturbance, and the legality of any action in grading a
site.
SECTION 5. EFFECTIVE DATE. This Ordinance shall take effect immediately upon
its first publication.
Passed by the City Council of Salt Lake City, Utah, this 6th day of March , 2001.
/f.
CHAIRPERSON
ATTEST: i
IEF DEPUTY CITY R RD R
Transmitted to the Mayor on March 6, 2001 .
Mayor's Action: Approved. Vetoed.
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ATTEST:
CHIEF DEPUTY CITY R C RDER By r ''
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(SEA
Bill No. 10 of 2001.
Published: March 14, 2001
G:AOrdina0l\Slope hvaluation-Mar 1,2001 -Clean.doc
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