HomeMy WebLinkAboutORD 14B (1990)ORDINANCE NO. 14-B (1990)
'— AN ORDINANCE OF THE CITY COUNCIL OF THE CITY OF
DIAMOND BAR EXTENDING THE TERM OF AN INTERIM ZONING
ORDINANCE, ORDINANCE NO. 14 (1990) PURSUANT TO THE
PROVISIONS OF CALIFORNIA GOVERNMENT CODE SECTION
65858 AND MAKING FINDINGS IN SUPPORT THEREOF.
A. Recitals.
(i) On April 18, 1989, the City of Diamond Bar was
established as a duly organized municipal corporation of the State
of California and, on that date, the City Council adopted, by
reference, the Los Angeles County Code as the ordinances of the
City, including Title 22 thereof pertaining to Planning and Zoning
Regulations for the City of Diamond Bar. (Hereinafter said Title
22 shall be referred to as "the Zoning Ordinance.")
(ii) On October 16, 1990, pursuant to the provisions
of California Government Code Section 65858 (a), this City Council
adopted its Ordinance No. 14 (1990) adopting interim zoning
regulations pertaining to development involving hillside areas
which exceed a slope of ten percent (10%) within the City.
(iii) Pursuant to the provisions of California
Government Code Section 65858 (d) this City Council issued its
written report describing the measures taken to alleviate the
conditions which led to the adoption of Ordinance No. 14 (1990) and
Ordinance No. 14-A (1990) at least ten (10) days prior to the
expiration of Ordinance No. 14 (1990) and Ordinance No. 14-A
(1990).
(iv) A duly noticed public hearing as required by
California Government Code Section 65858 (a) was conducted and
concluded prior to the adoption of Ordinance No. 14-A (1990) and
this Ordinance.
(v) All legal prerequisites to the adoption of this
ordinance have occurred.
B. ordinance.
The City Council of the City of Diamond Bar does ordain
as follows:
Section 1. The City Council hereby specifically finds
that all the facts wet forth in the Recitals, Part A, of this
Ordinance are true and correct.
Section 2. The City Council hereby finds and determines
that the adoption of this Ordinance is categorically exempt from
the requirements of the California Environmental Quality Act of
1970, as amended, and the Guidelines promulgated thereunder
pursuant to Section 15305 of Division 6 of Title 14 of the
California Code of Regulations.
Section 3. The City Council finds and determines that
the development of proposed amendments to the Zoning Ordinance are
continuing; however, such development of amendments to the Zoning
Ordinance cannot be completed prior to the expiration of ordinance
No. 14 (1990) and Ordinance No. 14-A (1990).
Section 4. The City Council hereby specifically finds
that there are presently pending applications for development of
hillside areas which exceed a slope of ten percent (10%) which
would contradict the ultimate goals and objectives of the General
Plan and would not be subject to adequate local review under the
provisions of the Zoning Ordinance unless Ordinance NO. 14 (1990)
is extended and, further, that the approval of any such hillside
developments under the current provisions of the Zoning Ordinance
would result in an immediate threat to the public health, safety or
welfare of persons and property within the City of Diamond Bar.
Section 5. Ordinance No. 14 (1990) of the City of Diamond
Bar, as heretofore enacted under the authority of California
Government Code section 65858 (a), hereby is extended and shall be
of no further force and effect as of the 16th day of October, 1992.
Section 6. This Ordinance hereby is declared to be an
urgency measure pursuant to the terms of California Government Code
Sections 65858 (a) and 36937 (b), and this Ordinance shall take
effect immediately upon adoption.
Section 7. The City Clerk shall certify to the adoption
of this Ordinance and shall cause the same to be posted in three
(3) public places within the City of Diamond Bar pursuant to the
provisions of Resolution No. 89-6.
ADOPTED AND APPROVED this 17th day of September, 1991.
Mayor
I, LYNDA BURGESS, City Clerk of the City of Diamond Bar,
do hereby certify that the foregoing Ordinance was introduced at a
regular meeting of the City Council of the City of Diamond Bar held
on the 17th day of September, 1991, and was finally passed at a
regular meeting of the City Council of the City of Diamond Bar held
on the 17th day of September, 1991, by the following vote:
AYES: COUNCIL MEMBERS: Papen, Nardella,
Kim, Forbing
NOES: COUNCIL MEMBERS: None
ABSENT: COUNCIL MEMBERS: Werner
ABSTAINED: COUNCIL MEMBERS: None
ATTEST D
LyndA Burgess, ,City Clerk
of the City of Diamond Bar
EXHIBIT "A"
CITY OF DIAMOND BAR INTERIM HILLSIDE MANAGEMENT ORDINANCE
Section 1. Statement of Purpose.
The purpose of this ordinance is.-
A.
s:A. To preserve and protect the views to and from hillside areas in
order to maintain the identity, image and environmental quality of
the City of Diamond Bar;
B. To maintain an environmental equilibrium consistent with the native
vegetation, animal life, geology, slopes, and drainage patterns;
C. To facilitate hillside preservation through appropriate development
standards and guidelines of hillside areas. The guidelines are not
intended to be strict standards, but rather to provide direction
and encourage development which is sensitive to the unique
characteristics common to hillside properties, which include, but
are not limited to slopes, land form, vegetation and scenic
quality. Innovation in design is encouraged as long as the end
result is one which respects the hillside and is consistent with
the purposes expressed in this section and in the goals- and
objectives of the General Plan;
D. To ensure that development in the hillside areas shall be
concentrated in those areas with the least environmental impact and
shall be designed to fit the existing land form;
E. To preserve significant features of the natural topography,
including swales, canyons, knolls, ridgelines, and rock outcrops.
Development may necessarily affect natural features by, for
example, roads crossing ridgelines. Therefore, a major design
criterion shall be the minimization of such impacts;
F. To provide a safe means of ingress and egress for vehicular and
pedestrian traffic to and within hillside areas, with minimum
disturbance to the natural terrain;
I
G. To correlate intensity of development with the steepness of terrain
in order to minimize grading, removal of vegetation, land
instability and fire hazards;
H. To provide in hillsides, alternative approaches to conventional
flat land development practices by achieving land use patterns and
intensities that are consistent with the natural characteristics of
hill areas such as slopes, land form, vegetation and scenic
quality; and
I. To encourage the planning, design and development of home sites
that provide maximum safety with respect to fire hazards, exposure
to geological and geotechnic hazards, drainage, erosion and
siltation, and materials of construction; provide the best use of
natural terrain; and to prohibit development what will create or
increase fire, flood, slide, or other safety hazards to public
health, welfare, and safety.
section 2. Hillside Management District. —
All property which contains grades in excess of 10% shall comply witl
the following:
A. Definitions: The following definitions shall apply to this Section:
CONTOUR: A line drawn on a plan which connects all points of
equal elevation.
CONTOUR GRADING: A grading technique designed to result in earth
forms which resemble natural terrain characteristics. Horizontal
and vertical curve variations are often used for slope banks.
Contour grading does not necessarily minimize the amount of cut and
fill occurring.
CUT: •The mechanical removal of earth material.
CUT AND BILL: The excavating of earth material in one place and
depositing of it as fill in an adjacent place.
DRIVEWAY: A means of access over private property to a single
residential unit.
EFFECTIVE BULK: The effective visual bulk of a structure when
seen from a distance of from below.
ELEVATION: Height or distance above sea level.
EROSION: The process by which the soil and rock components of the
earth's crust are worn away and removed from one place to another
by natural forces such as wind and water.
FILL: A deposit of earth material placed by artificial means.
FINISH GRADE: The final elevation of the ground surface after
development, which is in conformity with the approved plan.
GRADING: To bring an existing surface to a designed form by
excavating, filling, or smoothing operations.
HILLSIDE: Refers to a parcel of land which contains grades in
excess of 10$.
NATURAL SLOPE: A slope which is not man-made. A natural slope
may retain natural vegetation during adjacent grading operations or
it may be partially or completely removed and replanted.
PAD: A level area created by grading to accommodate development.
RIDGE: A long, narrow, conspicuous elevation of land.
ROADWAY: A means of access over private property to more than
one residential unit.
SLOPE: An inclined ground surface, the inclination of which is
expressed as a ratio of horizontal distance (run) to vertical
distance (rise), or change in elevation. The percent of any given
slope is determined by dividing the rise by the run, multiplied by
100.
SLOPa, MAN-MADE: A manufactured slope consisting wholly or
partially of either cut or filled material.
SLOPE TRANSITION: The area where a slope bank meets the natural
terrain or a level graded area either vertically or horizontally.
PROMINENT RIDGE: A ridge or hill location which is visible from
a major arterial, secondary, or collector street, which forms part
of the skyline or is seen as a distinct edge against a backdrop of
land at least 300 feet horizontally behind it, or is so designated
by the Planning Director.
B. Hillsid* Designation
The following are standards for hillside slope categories to ensure
that development will complement the character and topography of
2
the land. The standards for one category may be applied to limited
portions of the property in an adjacent category when a project is
developed on property in more than one slope category.
Slope Category 3L Natural slope Site Standards
1. 10 to 14.9 Special hillside architectural and
design techniques that minimize
grading are required
in these Slope Categories.
2. 15 to 19.9 Structures shall conform to the
natural topography and natural grade
by using techniques such as split
level foundations of greater than 18
inches, stem walls, stacking and
clustering. Conventional grading may
be considered by the city for
limited portions of a project when
its plan includes special design
features, extensive open spage or
significant use of green belts-.
3. 20 to 24.9 Development within this category
shall be restricted to those sites
where it can be shown that safety,
environmental and aesthetic impacts
can be minimized. Use of large lots,
variable setbacks and variable
building structural techniques such
as stepped foundations are expected.
Structures shall be designed to
minimize the visual impact of their
bulk and height. The shape,
materials, and colors of structures
shall blend with the natural
environment. The visual and physical
impact of driveways and roadways
shall be minimized by eliminating
sidewalks, and reducing their widths
to the minimum required for
emergency access and following
natural contours, using grade
separations where necessary and
otherwise minimizing grading.
4. 25 and over. This is an excessive slope condition
and development is extremely
limited.
C. Density
The maximum number of residential dwelling units which may be
permitted to be constructed on a given parcel of land shall be the
calculated development limit less the number eliminated due to
environmental constraints as determined Pursuant to this ordinance.
Average Percent
Slope of Site
0.0 - 14.9%
15.0 - 17.4%
17.5 - 19.9%
20.0 - 22.4%
22.5 - 24.9%
25.0 - 27.4%
27.5 - 29.9%
30.0 - 32.9$
32.5 - 34.9%
35.0 and above $
Minimum Percent of Site to Remain in Natural
State (No Cut or Fill) or Be Developed Solely
For Recreational Purposes
32.5 $
40.0%
47.5$
55.0%
62.5$
70.0%
77.5%
85.0%
92.5%
100.0%
RATIO RUN/RISE
PERCENT RISE/RUN i
I
DEGREE ANGLE BETWEEN RUN 6 RISE
i
i
RUN
4
Figure 1: slope ratio percent slope and degree of slope are shown for
some hillsides of varying steepness
?P Qom? Q�V
20 I 11
(s)
3:1 7] t8
2:1 50 i 5
Y (:)
W '
N_
111 l:1 100 ag
i
RUN (HORIZONTAL)
1. Environmental Constraints - The maximum number of residential
dwelling units shall be further reduced by the impact of the
following development constraints, as determined by
environmental assessment, unless such development constraints
can be shown to have been eliminated or mitigated to the
satisfaction of the Planning Commission or the City Council on
appeal:
a. Land areas subject to inundation during a 100 -year storm.
b. Land areas which have been subject to wild fire.
C. Land areas which are above the hillside view line.
d. Land areas which are subject to geologic hazard,
landslide and debris over flow.
e. Land areas which lie within a federally recognized blue
line stream, or which contain significant riparian stream
bed habitats or other established plant formations which
constitute a significant natural feature or ecosystem or
which contain rare or endangered species.
i.p
E.
f. Significant vegetation formations and habitat areas.
g. Land areas which are within 100 feet of a significant
ridgeline or hiking trail.
h. Land areas containing significant archaeologic or
historic sites.
2. Exemption - Other provisions of this subsection to the
contrary notwithstanding, lots of record as of the date of
adoption of this Ordinance shall be entitled to a minimum of
one dwelling unit.
3. Administration: This Ordinance shall be administered in
conjunction with the provisions of Chapter 22.56 of the
Diamond Bar Municipal Code. Where a conflict or inconsistency
exists, the more restrictive regulation shall apply.
Uses Permitted.
Subject to conditional use permit, the uses and structures
permitted by the Hillside Management Ordinance shall be those uses
permitted in the underlying base district.
Hillside Management Standards and Guidelines.
The following Hillside Management Standards and Guidelines are
intended to ensure the appropriate management of hillside areas.
The Standards are requirements for the use, development, or
alteration of land in Hillside areas. The Guidelines are to be
utilized to provide direction to encourage development which is
sensitive to the unique characteristics common to hillside
properties. The purpose for the Guidelines is to protect existing
hillsides and to encourage innovation, to the extent that is, the
end result is one which respects the/hillside and is consistent
with the goals and policies of this Ordinance. The Guidelines
shall be used by the Planning Commission and the City Council in
evaluating those development proposals for which it is proposed to
go beyond the minimum standards herein specified.
Exceptions to the standards specified herein may be approved,
pursuant to the Conditional Use Permit (CUP) process, when the
approving agency determines that such exceptions are not materially
injurious to the intent of the standards and guidelines set forth
herein. In granting any such exception, the approving agency shall
set forth appropriate findings specifying the facts supporting its
determination.
In granting any such exception, the approving agency shall set
forth appropriate findings setting forth the facts supporting its '—
determination.
"Where the Planning Commission determines that the literal
enforcement of the provisions of this Ordinance for parcels which
may be too small and of a configuration which would create a
L
hardship, the Commission may vary from the standards contained
— herein; provided that a variation from the strict application of
the Code be accompanied by reduction in the maximum permitted
density to the extent deemed necessary to maintain the intent of
the Ordinance.
variations may include modifications of the setback requirements to
achieve clustering of development on the parcel, in order to main-
tain the grading, drainage, siting and circulation objectives of
the Ordinance; except that residential structures shall be sited
and designed in a manner which will, in the judgment of the
Planning Director, maintain a vertical and horizontal distance from
other residential structures which will provide a reasonable degree
of privacy, light and air between residential structures."
"Where development is proposed for a parcel which adjoins one or
more vacant, developable parcels, cooperation of the respective
property- owners is encouraged in the planning of the road network,
utilities plan and open space program for the area as a whole. The
City shall consider variations from the strict application of the
provisions of this Ordinance as may be needed to achieve
cooperation among all contiguous property owners of vacant,
developable properties, to the extent that such variation may
better achieve the objectives of this Ordinance". ,
section 3. A22lication Filing Requirements.
A. A natural features map, which shall identify all existing slope
banks, ridgelines, canyons, natural drainage courses, federally
recognized blue line streams, rock outcroppings, and existing
vegetation. Also depicted shall be landslides and other existing
geologic hazards.
H. A conceptual grading plan, which shall include the following -items
in addition to those required by the Municipal Code or as part of
the Submittal Requirement Checklist:
1. A legend with appropriate symbols which should include, but
not be limited to, the following items: top of wall, top of
curb, high point, low point, elevation of significant trees,
spot elevations, pad and finished floor elevations, and change
in direction of drainage.
2. A separate map with proposed fill areas colored in green and
cut areas colored in red, with areas where cut and fill exceed
depths established in the hillside development guidelines and
standards clearly shown. Additionally, the areas of cut and
fill, calculated as a percentage of the total site area, shall
be included on the plan.
3. Contours shall be shown for existing and natural land
conditions and proposed work. Existing contours shall be
depicted with a dashed line with every fifth contour darker,
and proposed contours shall be depicted as above except with
a solid line. Contours shall be shown according to the
following schedule:
7
Natural Slone Maximum Interval Feet
0% to 20% 2
Above 20% 5
C. A conceptual drainage and flood control facilities map describing
planned drainage improvements.
D. A Slope Analysis map for the purpose of determining the amount and
location of land as it exists in its natural state falling into
each slope category as specified below. For the slope map, the
applicant shall use a base topographical map of the subject site,
prepared and signed by a registered civil engineer or licensed land
surveyor, which shall have a scale of not less than 1 inch to 100
feet and a contour interval of not more than 2 feet provided that
the contour interval may be 5 feet when the slope is more than 20
percent. This base topographical map shall include all adjoining
properties within 150 feet of the site boundaries. Delineate slope
bands in the range of to 10 percent, 10 up to 15 percent, 15 up to
20 percent, 20 up to 25 percent, 25 up to 30 percent, 30% to 35%
and 35 percent or greater. Also included shall be a tabulation of
the land/area in each slope category specified in acres.
Comoining •8' and •C- is
not a permitted oaieuiation
20*
Slope 'B-
30'
Stops •A' � 5•
too'
SLOPE FORMULA
Average Cross Slope - Slope -A-
• Slope -a-
Slope C.
8
6'
57100* a .05 ■ 5%
30'120' a 1.50 a 150%
6'130' a .2 a 20%
The exact method for computing the percent slope and area of each
slope category should be sufficiently described and presented so
that a review can be readily made. Also, a heavy, solid line
indicating the 8 percent grade differential shall be clearly marked
on the plan, and an additional copy of the map shall be submitted
with the slope .percentage categories depicted in contrasting
colors.
E. Provide a sufficient number of slope profiles to clearly illustrate
the extent of the proposed grading. A minimum of 3 slope profiles
shall be included with the slope analysis. The slope profiles
shall:
1. Be drawn at the same scale and indexed, or keyed, to the slope
analysis map, grading plan, and project site map.
2. Show existing and proposed topography, structures, and
infrastructures. Proposed topography, structures, and
infrastructures shall be drawn with a solid, heavy line.
Existing topography and features shall be drawn with a thin or
dashed line.
3. The slope profile shall extend far enough from the project
site boundary to clearly show impact on adjacent property; at
least 150 feet.
4. The profiles shall be drawn along those locations of the
project site where:
(a) The greatest alteration of existing topography is
proposed; and,
(b) The most intense or bulky development is proposed; and,
(c) The site is most visible from surrounding land uses; and,
(d) At all site boundaries illustrating maximum and minimum
conditions.
5. At least two of the slope profiles shall be roughly parallel
to each other and roughly perpendicular to existing contour
lines. At least one other slope profile shall be roughly at a
45 degree angle to the other slope profiles and existing
contour lines.
F. Both the slope analysis and slope profiles shall be stamped and
signed by either a registered landscape architect, civil engineer,
or land surveyor indicating the datum, source, and scale of
topographic data used in the slope analysis and slope profiles, and
attesting to the fact that the slope analysis and slope profiles
have been accurately calculated and identified.
9
G. A geologic and soils report, prepared by an approved soils
engineering firm and in sufficient detail to substantiate and
support the design concepts presented in the application as
submitted. Additional environmental studies and investigations,
Such as, but not limited to, hydrologic, seismic,
access/ circulation, and biota •research may also be required in
order to help in the determination of the buildable area of a site.
H. A statement of conditions for ultimate ownership and maintenance of
all parts of the development including streets, structures and open
spaces.
I. In the event that no grading is proposed, i.e., custom lot
subdivision, a statement to that effect shall be filed with a plan
which shows possible future house plotting, lot grading, driveway
design, and septic system location for each parcel proposed, to be
prepared on a topographic map drawn at the same scale as the
conceptual grading plan.
J. When unit development is proposed, illustrative building
elevations, that show all sides of the proposed structure(s) and
which accurately depict the building envelope for each lot, shall
be provided.
K. The following items may be required if determined necessary by the
Planning Director or Planning Commission to aid in the analysis of
the proposed project to illustrate existing or proposed conditions
or both:
1. A topographic model;
2. A line of sight or view analysis;
3. Photographic renderings;
4. Any other illustrative technique determined necessary to aid
in review of a project.
L. Exceptions to the filing requirements shall be determined by the
Planning Director.
Section 4. Public Safety Standards.
A. Fire protection Standards
1. Residential developments shall be constructed in such a manner
so as to reduce the potential for spread of brushfire through
consideration of the following:
a. In the case of a conflict where more restrictive
provisions are contained in the Uniform Building Code or
in the Fire Code, the more restrictive provisions shall
prevail.
10
b. Roofs shall be covered with noncombustible materials as
defined in the Building Code. Open eave ends shall be
stopped in order to prevent bird nests or other
combustible material lodging within the roof and to
preclude entry of flames .
C. Exterior walls shall be surfaced with noncombustible or
fire resistant materials.
d. Balconies, patio roofs, eaves and other similar overhangs
shall be of noncombustible construction or shall be
protected by fire-resistant material pursuant to the
Building Code.
2. Residential developments shall be constructed with adequate
water supply and pressure for all proposed development in
accordance with standards established by the Fire Marshal.
3. A permanent fuel modification area shall be required around
development projects or portions thereof that are adjacent or
exposed to hazardous fire areas for the purpose of fire
protection. The required width of the fuel modification area
shall be based on applicable building and fire codes and a
Fire Hazard Analysis Study developed by the Fire Marshai,
4. Fuel modification areas shall incorporate soil erosion -and
sediment control measures to alleviate permanent scarring and
accelerated erosion.
5. If the Fire Marshal determines in any specific case that
difficult terrain, danger of erosion or other unusual
circumstances make strict compliance with the clearance of
vegetation undesirable or impractical, he may suspend
enforcement thereof and require reasonable alternative
measures designed to advance the purposes of this ordinance.
6. In the event the abatement is not performed as required in
subsection C of this section, the City Council may instruct
the Fire Marshal to give notice to the owner of the property
upon which said condition exists to correct such prohibited
condition and, if the owner fails to correct such condition,
the City Council may cause the same to be done and make the
expense of such correction a lien on the property upon which
such conditions exist.
7. Require special construction features in the design of
structures where site investigations confirm potential
geologic hazards.
11
B. Gradinq
The following standards define basic grading techniques which are
consistent with the ordinance and avoid unnecessary cut and fill.
Limitations on project grading amounts and configurations will be
decided on a case-by-case basis under the conditional use process.
1. Standards.
a. No finished slopes greater than fifty percent (50% or
2:1) may be created except beneath a structure where the
maximum created slope is limited to sixty-seven percent
(67% or 1h:1) or less.
b. Grading shall be phased so that prompt revegetation or
construction will control erosion. Where possible, only
those areas which will be built on, resurfaced, or land-
scaped shall be disturbed. Top soil shall be stockpiled
during rough grading an used on cut and fill slopes.
Revegetation of cut and fill slopes shall occur within
three (3) months to the satisfaction of the City.
C. Grading operations shall be planned to avoid the rainy
season, October 15 to April 15. Grading permits shall
only be issued when a plan for erosion control and -gilt
retention has been approved by the City Engineer without
regard to time of year.
d. No excavation or other earth disturbance shall be
permitted on any hillside area prior to the issuance of
a grading permit with the exception of drill holes and
exploratory trenches for the collection of geologic and
soil data. These trenches are to be.properly backfilled
and in addition, erosion treatment provided where slopes
exceed twenty (20) percent.
e. No point on any structure subject to the provisions of
this Section shall be closer to a prominent ridge than
one hundred (100) feet measured horizontally on a
topographic map or fifty ( 50) feet measured vertically on
across section, whichever is more restrictive. And in no
case, shall the roof line or any other portion of a
structure extend above the line of sight between a ridge
line and any public right of way, whether said ridgeline
is above or below the right of way.
f. Lot pad grading is limited to the boundaries of the
structure's foundation, vehicle parking space and a yard
area as shown on the approved grading plan.
12
g. Cut slopes for purposes of establishing building pads
shall not exceed twenty (20) feet in height and fill
slopes shall not exceed eight (8) feet in depth at any
point on the site.
h. Retaining walls associated with lot pads are limited to:
i. Upslope (from the structure) walls not to exceed
four (4) feet in height. Terraced retaining
structures may be utilized which are separated by a
minimum of three (3) feet and appropriate
landscaping.
ii. Downslope (from the structure) walls not to exceed
three and 1/2 (3 1/2) feet in height. Where an
additional retained portion is necessary due to
unusual or extreme conditions, (such as lot
configuration, steep slope or road design) then the
use of terraced retaining structures shall be
considered on an individual lot basis. Terraced
walls shall not exceed three (3) feet in height and
shall be separated by a minimum of three (3) feet
and appro-priate landscaping. Terracing shall not
be used as a typical solution within a development.
-- iii. Retaining walls which are an integral part of the
structure shall not exceed eight (8) feet in
height. Their visual impact shall be mitigated
through contour grading and landscape techniques.
i. Lot lines shall be placed two feet beyond top of major
slope areas within public view corridors to help ensure
their maintenance by the downhill owner.
2. Guidelines.
a. Contour grading techniques should be used to provide a
variety of slope percentage and slope direction in a
three dimensional undulating pattern similar to existing,
adjacent terrain. Hard edges left by cut and fill
operations should be given a rounded appearance that
closely resembles the adjacent natural contours.
b. Where possible, graded areas should be designed with
manufactured slopes located on the uphill side of
structures, thereby, hiding the slope behind the
structure.
13
THS
Larger manufactured slope• should
be located on the upnill side of the
structure to reduce the appearance
of gra/dlog from the street
1
Slopes should be rounded to
provide a more natural appearance
' Street
NOT THIS
1
•. � SbNt
3. Retaining walls are limited to:
a. One upslope (from the structure) not to exceed 4 feet in
height. Otherwise, terraced retaining structures shall
be utilized which are separated by a minimum of 3 feet
and appropriate landscaping.
THIS
NOT THIS
14
b. One downslope from the structure not to exceed 3 1/2 feet
in height. Where an additional retained portion is
necessary due to unusual or extreme conditions, (such as
lot configuration, steep slope, or road design) then the
use of terraced retaining structures shall be considered
on an individual lot basis. Terraced walls shall no
exceed 3 feet in height and shall be separated by a
minimum of 3 feet and appropriate landscaping. Terracing
is not to be used as a typical solution within a
development.
C. On lots sloping with the street, and other configurations
not discussed above, one retaining wall, not to exceed 3
1/2 feet in height may be used in a side yard where
necessary (also see roadway).
d. Walls which are an integral part of the structure may
exceed 8 feet in height; however, their visual impact
shall be mitigated through contour grading and landscape
techniques.
4. The following factors shall be taken into consideration in the
design of a project: .6.
a. When space and proper drainage requirements can be met
with approval by the City Engineer, rounding of slope
tops and bottoms shall be accomplished.
b. When slopes cannot be rounded, vegetation shall be used
to alleviate a sharp, angular appearance.
C. A rounded and smooth transition shall be made when the
planes of man-made and natural slopes intersect.
d. When significant landforms are "sliced" for construction,
the landforms shall be rounded as much as possible to
blend into natural grade.
e. Manufactured slope faces shall be varied to avoid
excessive "flat -planed" surfaces.
5. No manufactured slope shall exceed 30 feet in height between
terraces or benches.
15
Retain Me integrity
THIS of the natural slop.
NOT THIS
Overemphasized vertical
structures disrupt the natural
silhouette of the hillside
i
a. Where cut or fill conditions are created, slopes should be
varied rather than left at a constant angle which may be
unstable or create an unnatural, rigid, "engineered"
appearance.
Varying cut or fill slope creates
a more natural appearance
16
b.
c.
The angle of any graded slope should be gradually adjusted to
the angle of the natural terrain.
49 Existing development Proposed development
I �
Tract boundary
,-C= � I
/
Natural grade Variable`��`
Prepesed $lop• extension
Existing drainage device \\ This 'Natural grade
Not
Combine slopes to more closely
approximate natural grade
Hard edges left by cut and fill operations should be given a
rounded appearance that closely resembles the natural contours
of the land.
THIS
NOT THIS
Small irregular berm accentuates
the top or the slope
Variety in
:lope bank f
grading ��� .. landscaping
creates a �,'� ems—
accentuates
nf Lln ' contour unoulation
natural apo ` _r �I
more resembling a
t .i
hatYff !�o
1 Engine?
Drainage banks Iand unt
features are
obscured
t i
Drainage
features
become
\ very visible
lid slope �\jjj
sk forest
aural I
Use of radii and uneven slopes Use of angles and unslorm slopes
17
d. Manufactured slopes adjacent to roadways should be modulated.
by sufficient berming, regrading, and landscaping to create
visually interesting and pleasing streetscapes.
THIS
NOT THIS
section 5. Drainage
Where a conflict exists between the provisions of this section and
Chapter 70 of the Uniform Building Code, the drainage, soils and geology
provisions of Chapter 70 shall prevail, unless in the opinion of the
City Engineer, the provisions of this section meet sound engineering
standards consistent with the standards of Chapter 70.
A. Standards.
1. Debris basins, rip rap, and energy dissipating devices shall
be provided where necessary to reduce erosion when grading is
undertaken. Except for necessary flood control facilities,
significant natural drainage courses shall be protected from
grading activity. In instances where crossing is required, a
natural crossing and bank protection shall be preferred over
steel and concrete systems. Where brow ditches are required,
they shall be naturalized with plant materials and native
rocks.
18
2. Building and grading permits shall not be issued for
construction on any site without an approved location for
disposal of runoff waters, including but not limited to such
facilities as a drainage channel, public street or alley, or
private drainage easement.
3. All cuts shall be drained.
4. The use of cross lot drainage shall be subject to Planning
Commission review and may be approved after demonstration that
this method will not adversely affect the proposed lots or
adjacent properties, and that it is absolutely required in
order to minimize the amount of grading which would result
with conventional drainage practices. Where cross lot drainage
is utilized, the following shall apply:
a. Project Interiors - One lot may drain across one other
lot if an easement is provided within either an improved,
open V-swale gutter, which has a naturalized appearance,
or within a closed drainage pipe which shall be a minimum
twelve (12) inches in diameter. In both cases, an
integral wall, shall be constructed. This drainage shall
be conveyed to either a public street or to a drainage
easement. If drainage is conveyed to a private easement,
-- it shall be maintained by a homeowners association,
otherwise the drainage shall be conveyed to a public
easement. The easement width shall be determined on an
individual basis and shall be dependent on appropriate
hydrologic studies and access requirements.
b. Project. Boundaries - Onsite drainage shall be conveyed in
an improved open V-swale, gutter, which has a naturalized
appearance, or within an underground pipe in either a
private drainage easement, which is to be maintained by
a homeowner's association, or it shall be conveyed in a
public easement. The easement width shall be determined
on an individual basis and shall be dependent on
appropriate hydrologic studies and access requirements.
19
THIS
Variable i
Use of native rocks to
naturalize man-made
brow ditch
NOT THIS
I with
line?
B. Guidelines.
1. Where possible, drainage channels should be placed in
inconspicuous locations, and more importantly, they should
receive a naturalizing treatment including native rock,
colored concrete and landscaping, so that the structure
appears as an integral part of the environment.
�.���^�G �re�9 � +may. r•�' ' � � 5^1���• ..�.\I{ � � '� - ` ^-
20
2. Natural drainage courses should be preserved and enhanced to
the extent possible. Rather than filling them in, drainage
features should be incorporated as an integral part of the
project design.
section 6. Access as parkins.
A. standards.
1. Driveway grades up to a maximum of twenty (20) percent are
permitted, and shall be aligned with the natural contours of
the land. Proper design considerations shall be employed,
including such items as vertical curves and parking landings.
In any case, parking landings shall be utilized on all drives
over ten (10) percent grade.
2. Driveways shall not be permitted which exceed twenty (2 0)
percent slope except that* one length, not at the point of
access, of not more than ten (10) feet may have a slope of
twenty-two (22)percent.
3. Grooves for traction shall be incorporated into the construc-
tion of driveways with a slope of twenty (20) percent or
greater, a coarse paving matter into the construction. --
THIS
r g.I r n+es
r
Street
21
Siriet 1
r ^ _
�a ; �• mes
r g.I r n+es
r
Street
21
Siriet 1
4. Where retaining walls are necessary adjacent to roadways or
within street setbacks, they shall be limited to three (3)
feet in height in order to avoid obstruction of motorists' and
pedestrians' field of view, and to create an aesthetically
pleasing streetscape. No more that three (3), three (3) foot
high terraced or stepped retaining walls shall be utilized
which are separated by a minimum of three (3) feet and
appropriate landscaping. Slopes not greater than fifty (50)
percent (or 2:1) -will be permitted upon review and approval by
the Fire Marshall.
5. Driveways shall enter public/private streets maintaining
adequate line of sight.
6. Local hillside street standards shall be used to minimize
grading and erosion potential while providing adequate access
for vehicles, including emergency vehicles. The right-of-way
may be a minimum of 48.5 feet with 40 feet of paved width and
parking on both sides and a sidewalk on 1 side.
7. Grades of streets in the hillside areas shall be as provided
in this subsection. Hillside collector and arterial streets
shall not exceed 8 percent. Hillside residential local stteets
shall not exceed 12 percent.
8. Cul-de-sacs to a maximum of 750 feet in length may be
permitted with a maximum of 30 dwelling units, and to a
maximum of 1000 feet in length with a maximum of 20 dwelling
units and shall terminate with a turn around area not 'less
than 35 feet in radius to curb face.
9. All other street improvement standards shall conform to the
standard plans and specifications for public streets of the
City of Diamond Bar.
10. The Planning Commission may approve modifications to the above
right-of-way design standards provided such modifications are
in substantial conformance with the objectives stated in this
section.
B. Guidelines.
1. Roadways and driveways, where feasible, where feasible, should
conform to the natural landform. They should not greatly alter
the physical and visual character of a hillside by creating
large notches in ridgelines or by defining wide straight
alignments or by building switch -backs on visually prominent
hillsides, split sections and parking bays should be utilized _
in the layout of hillside streets.
22
THIS
f
! Reduce grading by
aligning roads along
natural grades
NOT THIS
Roads and hillside grading
Avoid running counter
to step grams
A
I To got tram A to 8. route selection would
be somewhere between perpendicular and
parallel to the contours
2. where road construction is permitted in hillside areas, the
extent of vegetation disturbance and visual disruption should
be minimized by the combined use of retaining structures and
regrading to approximate the natural slope. The following
techniques should be used where feasible:
a. Utilize landform planting in order to create a natural
appearance and provide a sense of privacy.
23
b. Reduce the visual and safety impacts by use of terraced
retaining walls and landscaping.
C. Split roadways increase the amount and appearance of
landscaping and the median can be used to handle
drainage.
No parking
Stabilize and reforest
distributed banks
Separate sidewalk
Steep slope
Split section Roadway i
Parking as
J I
.r
r
Steep slopes
Possible trail Sidewalk
IRoadway
^i Flatter slope
Section 7. Trails
A. Trails are an integral part of a hillside area and provide
recreation areas for equestrian, hiking and biking uses. They can
also function as a means to take up grade or to convey drainage.
In hillside areas, it is not always necessary to provide full
improvements for trails. A more natural experience may be
achieved, and the amount of grading required can be reduced, by
providing minimal improvements in appropriate areas, such as
undevelopable, steep slopes. ._
24
Section S. Roadways.
A. Where retaining walls are proven to be absolutely necessary
adjacent to roadways or within street setbacks, they shall be
limited to 3 feet in height in order to avoid obstruction of
motorist's and pedestrian's field of mew and to create an
aesthetically pleasing streetscape. Otherwise, terraced or stepped
structures shall be utilized, which are separated by a minimum of
3 feet and appropriate landscaping.
NOT THIS
Unnatural edge condit'an
1 Cut slope
into hillsid
Roatlway
Knob remaining
�Irom roadway cut
Roadway
!I
Too steep for plants
• to become established
Mass grading to accommodate
one level arterial highway
N. Natural grad
Roadway \
THIS
25
Round off cut slopes
Removesmall knobs
on roadway cut
\ to can to the
natural grade
Vista
Roadway
Round off
cut slopes Split roadway sections to
'
�accommodate grade
change
}
\ Natural grade i
Roadway I/
IL
Roadway
Section 9. Site Design-
A.
esi n.A. Standards.
1. The dimensions of a building parallel to the direction of the
slope shall be maximized .in order to limit the amount of
cutting and filling and to better fit the house to the natural
terrain.
THIS
NOT THIS
Terraced decks do not s r ^ Overhanging decks
increase building bulk make building
Seem more f I
Effective bulk with massive !• ✓/
r
Or without deerca - Effective bulk
Building correctly fits
into the ground and �--�
minimises the effect
on the hillsides -r
Use of roof decks, low
level decks, and side of i
building decks
Terracing reduces bulk
Effective bulk
� Asa
Effective bulk
Smaller overhangs lot individual floors
or windows help bteak•up masa and
protect against excessive sunlight
Nigh profile building
stands out on the
hillside - +
Avoid decks hanging
from the downhill side
with long pole supports
Cantilever makes building
appear tailor, more
monumeniat•
Effective bulk FF
Excessive roof overhang
results in additional
visual bulk
Effective bulk ~�
26
B. Guidelines.
1. Design of building sites should be sensitive to the natural
terrain. Structures should be located in such a way as to
minimize necessary grading and to preserve natural features
such as prominent knolls or ridgelines.
2. Views of significant visual features as seen from both within
and outside a hillside development should be preserved. The
following provisions shall be taken into consideration:
a. Dwellings should be oriented to allow view opportunities,
although such views may be limited. Residential privacy
should not be unreasonably sacrificed.
b. Any significant public vista or view corridor as seen
from a secondary, collector or major arterial should be
protected.
3. Projects should incorporate variable setbacks, multiple
orientations and other site planning techniques to preserve
open spaces, protect natural features and offer views to
residents.
THIS
NOT THIS
section 10. Architecture.
A. standards.
1. The building envelope for all structures shall be as follows:
_ a . Downhill lat - A maximum/ height of thirty -f ive ( 35) feet
as measured from natural grade at the front setback,
extending towards the rear of the lot. The maximum height
at the side setbacks shall be twenty (20) feet extending
27
up to the center of the lot at a forty-five (45) degree
angle to a maximum height of thirty-five (35) feet as
measured from natural grade.
BUILDING ENVELOPE FOR DOWNHILL LOT
35;
357'
Y
I _G
Minimum front setback
I i
0
Downhill Section y
Rear, setback
I t�
r'— Minimum side setbaeft
Street Elevation _
-b. Uphill 3S& - A maximum height of twenty (20) feet at the
front setback extending up and toward the rear of the lot
at a forty-five (45) degree angle to a maximum height of
thirty-five (35) feet as measured from natural grade. A
maximum height side setbacks shall be twenty (20) feet
extending up to the center of the lot at a forty-five
(45) degree angle to a maximum height of thirty-five
(35) feet as measured from natural grade.
C. Cross 81020 Lots - A maximum height of thirty-five (35)
feet, as measured from natural grade, at the front
setback extending toward the rear of the lot. The maximum
height at the side setbacks shall be twenty (20) feet
extending up to the center of the lot at a forty-five
(45) degree angle to a height of thirty-five (35) feet as
measured from natural grade.
28
THISLarg• root 20CtiOAS 10
Parallel the average slop•
Height limit —y
Building onrelop•
Maximum height limit
Softening of large \.�
vertical surfaces /
NOT THIS
a
height limit
2. The building shall be terraced to follow the slope.
3. Architectural treatment shall be provided to all sides of the
structure visible from adjacent properties, roadways or public
rights of way.
4. Exterior structural supports and undersides of floors and
decks not enclosed by walls shall be permitted provided fire
safety and aesthetic considerations have been adequately
addressed.
5. Exterior flood lighting for safety shall be located and
shielded so as not to shine on adjacent properties. Decorative
lighting to highlight a structure is prohibited.
29
THIS
Large root areas broken up
Use of natural materials and window
placement in small increments create
interesting small scale patterns
NOT THIS
Massive roof area is very visible in
contrast to the natural slope
z;
Break up massing of structural elements Large facade of one material, even
to more closely approximate the natural
slope if modulated by windows, seems plain
Stone foundations and retaining wails
relate to the ground
B. Guidelines.
1. The form, mass and profile of the individual buildings and
architectural features should be designed to blend with the
natural terrain and preserve the character and profile of -the
` natural slope. Some techniques which may be considered
include:
a. Split pads, stepped footings and grade separations to
permit structure to step up the natural slope.
b. Detaching parts of a dwelling such as a garage.
C. Avoid the use of gable ends on downhill elevations. The
slope of the roof should be oriented in the same
direction as the natural slope and should not exceed
natural slope contour by twenty (20) percent.
2. Avoid excessive cantilevers on downhill elevations.
3. Excavate underground or utilize below grade rooms to reduce
effective bulk and to provide energy efficient and environ-
mentally desirable spaces. However, the visible area of the
building shall be minimized through a combined use of
regrading and landscaping techniques.
4. Use roofs on lower levels for the deck open space of upper
levels.
5. Building materials and color schemes should blend with the
natural landscape of earth tones and natural chaparral
vegetative growth.
30
6. To the extent possible, the width of a building measured in
the direction of the slope, shall be minimized in order to
limit the amount of cutting and filling and to better "fit"
the house to the natural terrain.
THIS
Building pulls back I►om
steopor slop•$ and ravines
y on the hillside
Minor building
protrusions which
ar• perpendicular to th•
contours are acceptable
but should be stepped or
inset in the hillside
Building is parallei with NOT THIS
the contours
.
•
•
Building is perpendicular to the contours
Section 11. Fences AM Landscaping.
A. standards.
1. Walls and fencing, not exceeding six (6) feet in height,
visible from roadways or public rights-of-way shall be
visually open and non-opaque.
2. Privacy walls and fences, not exceeding six (6) feet in
height, are permitted adjacent to structures, in order to
provide a private outdoor area. Walls and fences shall be of
materials and colors compatible with the structure's facade.
31
3. Native or naturalized plants or other plant species that blend
with the landscape shall be utilized in all areas with
required planting.
4. Fire retardant plant materials shall. be utilized. Plants
selected as ground cover, shrubs or trees shall be from the
list as approved by the City.
5. A permanent irrigation system, for purposes of establishing
and maintaining required planing, shall be installed on all
slopes. The emphasis shall be toward using plant materials
that will eventually need minimal irrigation. Water and
energy conservation techniques shall be utilized including but
not limited too such items as drip irrigation.
THIS
planting pockets on stepped
retaining wall allow screen
planting at several levels
No elfective bulk
NOT THIS
Effective bulk
No planting possible due
to toe of retaining wall
J J
f /
Large concrete retaining well
surfaces can be seen lo♦ Milos
and take years to eoneeaf
with planting and trees
6. Landscaping shall be used to screen views of downslope
building elevations. When the structure height exceeds twenty
(20) feet from finished grade on a downslope, additional
landscaping is required and a landscaping plan shall be
submitted for review with the submittal package.
32
7. Slopes with required planting shall be planted with informal
clusters of trees and shrubs to soften and vary the slope
plane. Where slopes are 2:1 and five (5) feet or greater in
height, jute netting shall be used to help stabilize planting
and minimize soil erosion.
8. Native vegetation shall be retained and supplemented within
canyons and along natural drainage courses as allowed by state
and federal resource agencies (State Department of Fish &
Game, U. 5. Fish and Wildlife, U. S. Army Corp. of Engineers).
THIS
NOT THIS
planting naturally follows
the average slope
Open see-thru fencing that
t�blends into the natural environme
3.5'masimum retaining wail
Screening required.
Trfnsitlon area ` tail
Highly risible solid wall
Over 3X(not allowed)
Clear cut separation Me screening
between natural eendltlen «-
and developed area .,th no transition
B. Guidelines.
1. Natural landform planting should be used to soften
manufactured slopes, reduce impact of development on steep
slopes or ridgelines, and provide erosion control.
33
2. Maintain a "vegetative backdrop" by replanting with approved
trees. The vegetation should screen structures to the extent
possible at maturity and preserve the appearance of the
natural hillside.
skylln.
Typical building clustering
3. Natural landform planting should be used to soften manufac-
tured slopes, reduce the impact of development on steep slopes
or ridgelines, and provide erosion control.
THIS
Landform planting
irregular visual plan*
in cross-s.ntien
-NOT THIS
soctn"
Conventional planting
Uniform visual plan*
in cress -section
/ . .=
/ter` 4 _
Section 34