M3 Hillside & Grading Standards FINALJUL 2 8 2009
He,
Routs to:
M3 EAGLE
GRADING GUIDELINES AND
HILLSIDE DEVELOPMENT STANDARDS
FINAL
APPROVED BY CITY COUNCIL
11 /24/09
Table of Contents
INTRODUCTION........................................................................................................................................1
M3 EAGLE PRE -ANNEXATION AND DEVELOPMENT AGREEMENT..........................................1
EXISTINGCONDITIONS..........................................................................................................................2
1. Topography......................................................................................................................................2
2. Soils..................................................................................................................................................2
3. Vegetation........................................................................................................................................2
4. Viewshed..........................................................................................................................................3
GRADING AND DEVELOPMENT CRITERIA.......................................................................................3
1. Conceptual Grading Plan..............................................................................................................3
2. Grading Typologies........................................................................................................................3
a. Restricted Grading......................................................................................................................5
b. Limited Grading...........................................................................................................................6
c. Moderate Grading.......................................................................................................................7
d. Standard Grading.......................................................................................................................8
3. General Grading Principles and Guidelines...............................................................................8
4. Specific Grading and Siting Guidelines.....................................................................................11
a. Streets and Roadways.............................................................................................................11
b. Development Pads/Lots...........................................................................................................13
c. Structures...................................................................................................................................17
d. Retaining Walls.........................................................................................................................18
e. Driveways..................................................................................................................................19
f. Drainage.....................................................................................................................................19
g. Compaction................................................................................................................................19
5. Landscape/Erosion Control.........................................................................................................20
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GRADING PLAN REQUIREMENTS, REVIEW, and APPROVAL..................................................21
1.
Engineering Reports....................................................................................................................21
a.
Soils Report ...............................................................................................................................21
b.
Geology Report .........................................................................................................................22
c.
Hydrology Report......................................................................................................................22
2.
Grading Plans............................................................................................................................2324
a.
Mass Grading Plan...............................................................................................................232-2
b.
Mass Grading Permit...............................................................................................................23
c.
Final Grading Plan................................................................................................................272
d.
Final Grading Permit........................................................................................................27�5
3.
Grading Plan Review Process............................................................................................2827-26
List of Exhibits
Exhibit A - Conceptual Grading Plan..............................................................................................................4
ExhibitB - Grading Typologies.......................................................................................................................5
ExhibitC - Slope Rounding............................................................................................................................9
ExhibitD - Slope Variation...........................................................................................................................10
ExhibitE - Road Grading..............................................................................................................................11
ExhibitF - Road Integration.........................................................................................................................12
ExhibitG - Lot Line at Top of Slope.............................................................................................................13
ExhibitH - Lot Line Along Slope...................................................................................................................14
Exhibit I - Minimum Slope Setback Example...............................................................................................15
Exhibit J - Building Envelope Example.........................................................................................................15
ExhibitK - Flat Pad Design...........................................................................................................................16
Exhibit L - Grade Adaptive Pad Design........................................................................................................16
Exhibit M - Building Envelope Design..........................................................................................................17
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Exhibit N - Grade Adaptive Architecture.....................................................................................................17
Exhibit0 - Retaining Wall............................................................................................................................19
Appendices
AppendixA - Existing Landforms.............................................................................................................3025
AppendixB - Existing Slopes....................................................................................................................3129
AppendixC - Existing Vegetation............................................................................................................3230
Appendix D - Visual Sensitivity Analysis..............................................................................................333231
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INTRODUCTION
The North Eagle Foothills have been designated by the City as an Area of Critical
Concern for topographic, ecological and scenic significance. Although M3 Eagle
contains some of the most developable land in the foothills, the property is
topographically varied and contains hillsides with some slopes exceeding 25% grade,
which are considered constrained lands for development purposes. Due to the unique
size, intensity, and nature of the M3 Eagle project and unique conditions of the M3
Eagle property, the M3 Eagle Pre -Annexation and Development Agreement requires the
submission and approval of "grading guidelines and hillside development standards"
prior to development on such lands in order to establish the appropriate grading
techniques and mitigation actions that will help minimize development impacts on
existing topography. Once these standards are adopted they will serve as the guide for
preparing and reviewing engineering reports, development proposals, and grading plans
for the property.
This document replaces existing Eagle City Code 9-5-3, Hillside Subdivisions, and
establishes a set of principles and specific techniques that will guide grading,
improvement design, and site development on hillsides and other areas within M3
Eagle. It also describes the reports and plans that will be required of the developer for
review and approval by the City prior to grading. These criteria include and exceed the
standards from existing Eagle Code and provide more site specific restrictions and
additional grading criteria. Ultimately, they will reduce the impact of development on the
land and provide for a harmonious blending of development with landform while
establishing clear and measurable standards for the developer and the City to work
from.
M3 EAGLE PRE -ANNEXATION AND DEVELOPMENT AGREEMENT
The City of Eagle approved the M3 Pre -Annexation and Development Agreement on
December 11, 2007. Section 1.6 of the agreement provides for a maximum base
project density (Pre -Mitigation Density) of 5,127 dwelling units prior to conversion of
constrained lands to unconstrained lands. Slopes over 25% are considered constrained
(non -buildable) lands, but may be converted to unconstrained (buildable) lands by
implementing grading techniques described in this document. Existing slopes on the
property greater than 25% total approximately1,842 acres of which approximately 660
acres are proposed to be converted to buildable lands.
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EXISTING CONDITIONS
1. Topography
The topography of the site is varied, as shown on Appendix A. The Property rises
in elevation from 2,590 feet above sea level at the southwest corner of the site to
3,150 feet at the northeast corner. The Big Gulch area through the center of the
property is a relatively flat valley while the remainder of the site is primarily rolling
hills with parallel ridges and draws generally oriented northwest/southeast.
Approximately 70% (4,163 acres) of the site contains slopes under 25% while
approximately 30% (1,842 acres) of the site contains slopes over 25%, with a high
concentration of those steep slopes on property east of Willow Creek Road where
they are planned to be preserved as part of the Eagle Regional Park. The property
contains no significant rock features or uniquely defined landforms.
A breakdown of the approximate acreage of slopes under and over 25% by planning
area is shown on Appendix B.
2. Soils
M3 Eagle is underlain by Idaho Group sediments. Soil deposits generally consist of
sands, silts and clays or mixtures of the same and are of moderate constructability.
Ridgetops and steep slopes contain in -place soils which are silty or clayey sand and
occasionally poorly graded clean sand and clay. In general, soils on the property
are easily eroded and must be protected after exposure. Site specific geotechnical
explorations and analyses will be conducted prior to development to formulate
detailed recommendations for grading and design of structures and infrastructure.
3. Vegetation
M3 Eagle vegetation, as shown on Appendix C, is dominated by non-native
grasslands which comprise 90% (5,413 acres) of the property. Low lying shrubs
comprise 7% (420 acres) and disturbed lands (agriculture and development)
comprise 3% (170 acres). Over 92% (5,532 acres) of the vegetation is in poor to
marginal condition while the remainder is in satisfactory to good condition. There
are limited trees associated with existing residences on the western portions of the
property. The Development Agreement identifies two Habitat Areas of Special
Concern related to existing vegetation on the property. A habitat mitigation plan will
be approved by the City prior to submission of any grading plans within those areas.
This plan will identify a mitigation strategy to minimize loss of plant and animal
habitat as described in section 2.7, paragraph (d) of the Development Agreement.
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4. Viewshed
Portions of the property next to Highway 16 and Willow Creek Road are visible from
those roadways while the interior is predominantly hidden from view. In addition, the
property is separated both physically and visually from existing residences to the
south and the City of Eagle by BLM lands (the future Eagle Regional Park), which
consist of a ridge form running east and west along the southern border of the
property. These lands provide a natural visual buffer and substantial development
setback from existing rural neighborhood areas. A visual sensitivity analysis of the
North Eagle Foothills, a portion of which is shown on Appendix D, was conducted
by the City in 2006 and shows that the majority of the property exhibits moderate
visual sensitivity. The portion of the property exhibiting the highest visual sensitivity
is located east of Willow Creek Road on land that is planned to be preserved as
natural open space as part of the future Eagle Regional Park. Visually sensitive
ridges have also been identified along the west side of Willow Creek Road, as
shown on Appendix A, and development in those areas will be limited in order to
maintain their aesthetic value in accordance with paragraph 2.6 (c) of the
Development Agreement.
GRADING AND DEVELOPMENT CRITERIA
1. Conceptual Grading Plan
The property contains approximately 1,842 acres of slopes greater than 25%
(constrained lands), which represent approximately 30% of the site. About one third
of these slopes, or 660 acres, are planned to be graded, or mitigated, to create
slopes under 25% and make them suitable for development. The general location
and acreage of these slopes, as well as a tabulation by planning area of constrained
slopes planned to be mitigated, is shown on Exhibit A. Refined grading totals will
be provided with each planning unit master plan submittal so a cumulative analysis
of mitigated acreage can be conducted in accordance with section 1.6 of the
Development Agreement.
2. Grading Typologies
Grading will vary in scope and intensity depending on location, existing topography
and development patterns. Each planning area will undergo restricted, limited,
moderate or standard grading as shown on Exhibit B and as described below.
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Exhibit A - Conceptual Grading Plan
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Exhibit B - Grading Typologies
51,
Restricted grading operations are planned for regional open space in the eastern
portion of the property. Grading will be mainly limited to roadways, trails and
public facilities related to any park improvements or trailheads to preserve
existing habitat and open space values. Restricted grading operations will
comply with the following criteria:
1) Grading necessary for roadways, trails, public facilities, drainage
improvements, open space, recreational amenities and their supportive
uses is permitted. Grading will be minimized and sensitive to the existing
topography and landscape. Areas disturbed by grading will be restored to
a natural appearing state as much as possible.
2) Grading associated with habitat restoration and enhancement is permitted.
3) Retaining walls may be used to limit grading.
b. Limited Grading
Limited grading operations are planned for low density residential
neighborhoods, many of which will be comprised of custom lots on which limits of
development will be defined by building envelopes. Homes will generally be
located along flat to moderate slopes while steeper, non -graded slopes will
remain as open space. The majority of the Southern Planning Area will undergo
limited grading due to its topography and location next to the Eagle Regional
Park and Willow Creek Road, approximately 50 acres of slopes over 25% in this
planning area will be mitigated, of which half are made up of individual building
envelope areas. About 846 acres of slopes 25% and greater (including the
regional open space areas in the restricted grading category) are planned to
remain undisturbed. Limited grading operations will comply with the following
criteria:
1) All grading criteria associated with restricted grading operations will apply.
2) Grading associated with residential, commercial, educational, community,
and recreational uses is allowed.
3) Grading associated with residential lots one acre and larger will generally
be limited to building envelopes (where appropriate), driveways, pasture
areas and improvements associated with geotechnical engineering,
drainage improvements, fuel modifications, and other similar reasons.
4) Grading associated with public utilities, lakes, storage ponds, and
detention basins is allowed.
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5) Drainage channels may be relocated and improved in some areas to
reduce the existing floodplain in accordance with City floodplain
development permit policy (see Eagle City Code title 10).
6) Grading on sites next to the Eagle Regional Park and other regional open
space will blend the characteristics of those landforms into the sites as
much as possible.
7) Grading associated with agricultural uses is allowed which may include
hillside terraced grading for vineyards.
8) Retaining walls may be used to minimize grading.
c. Moderate Grading
Moderate grading operations will generally occur on gentle to steep slopes that
will undergo a moderate amount of landform alteration to accommodate
development. The Northern Planning Area is planned to undergo moderate
grading and will contain the most homes in the project along with schools, parks,
golf courses, and small commercial centers. Homes will be clustered and
located on flat areas, moderate slopes, and ridge tops with many steeper, non -
graded slopes left as open space. About 67% of the planning area, or 1,849
acres, contains slopes under 25%. Of the 911 acres of slope over 25%,
approximately 585 acres, or about 64%, will be graded to create clustered
building sites. A portion of the Southern Planning Area and Southwestern
Planning Area are planned for moderate grading as well. This will occur on two
sites along Linder Road and Hartley Road and the primary access roadway to
Highway 16 within the Southwestern Planning Area. These sites are planned for
employment or residential uses. The Highway/Mixed Use Planning Area is
planned to undergo moderate grading and is planned as a community center site
with retail, office and business park uses as well as potential residential units.
Over 93% of the planning area is made up of slopes less than 25%. Of the six
acres of slope over 25%, approximately 5 acres will be graded to create building
sites. Moderate grading operations will comply with the following criteria:
1) All grading criteria associated with limited grading operations will apply.
2) Grading associated with all land uses is allowed.
3) Some existing landforms will be modified and re -contoured, but the overall
effect will be to emulate the general character of the planning area.
4) Retaining walls may be used to minimize grading.
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5) Grading associated with golf courses will be permitted. Golf course edges
will be softened and re -contoured to blend seamlessly with the natural
topography.
d. Standard Grading
Standard grading operations will occur in the Big Gulch and Southwestern
Planning Areas, which are the flattest and least constrained portion of the site..
The Big Gulch Planning Area will contain the highest intensity of uses per acre
on the property and is planned for a mix of residential and commercial, civic and
recreational uses. About 95% of the area, or 610 acres, contains slopes under
25%. Of the remaining 26 acres with slopes over 25%, approximately 16 acres
will be graded to create suitable building sites. The Southwestern Planning Area
is planned for rural and estate type homes, medium density neighborhoods, and
an equestrian center. Over 99% of the area contains slopes under 25% and only
one acre of these slopes will be graded. Standard grading operations will comply
with the following criteria:
1) All grading criteria associated with moderate grading operations will apply.
2) Existing landforms may be significantly altered or eliminated to create
building sites.
3. General Grading Principles and Guidelines
General shapes of landforms in nature are fairly consistent. Ridges erode creating a
"U" like form. Valleys and drainage courses are cut in the land and create a steeper
"V" like form. This understanding and incorporation into grading design naturalizes
and blends graded areas into existing ground. Mass grading, like detailed grading,
should be an artful process. Planning and design should consider both vertical and
horizontal movement. Existing landforms and site characteristics should drive
grading concepts and placement of built elements. Landform grading should be
used instead of conventional grading wherever possible.
a. The basic landforms of the site, as depicted in Appendix A, should be
maintained. Existing landforms may be re -graded as necessary for development
so long as the overall site character is retained.
b. Manufactured slopes should resemble natural landforms and blend in with the
existing topography. Harsh angular lines should be avoided, where practicable,
in favor of slope rounding techniques to create a seamless transition between
existing and altered terrain.
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Exhibit C - Slope Rounding
CUT SLOPE EDGE
APPEARS UNNATURAL
l CONSTANT-2'1. GRADIENT
�L
I U \
CUT \�
STANDARD INTO
NOSE OR RIDGELINE V \
ROUNDED CUT EDGES
CONFORM TO
THE EXISTING TERRAIN
31
VARIETY IN UNDULATION AND
GRADIENTS CREATE A NATURAL
APPEARANCE AND PLEASING
LANDSCAPE ENVIRONMENT
Conventional Grading Landform Grading
c. Variation and combination of slopes, i.e. 2:1, 3:1, and 4:1 (50%, 33%, 25%), etc.
should be used to create a more natural character within graded areas where soil
conditions and ability to landscape allow. Large graded slopes with a constant
gradient are discouraged.
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Exhibit D - Slope Variation
ROUNDED CONTOURS
EMULATE EXISTING TERI
STRAIGNTCONTOURS '
AND CONSTANT GRADIENTS
APPEAR ENGINEERED AND -
UNNATURAL
Conventional Grading
VARIETY IN UNDULATION AND
GRADIENTS CREATE A NATURAL
APPEARANCE AND PLEASING
LANDSCAPE ENVIRONMENT
Landform Grading
d. The maximum gradient of any manufactured slope should not exceed 2:1 (50%).
Slopes as steep as 1:1 (100%) and as high as ten feet without offsets or benches
may be permitted under certain circumstances and on a case -by -case basis
where geologic or aesthetic conditions allow, or if best management practices
warrant and if certified by a professional geotechnical engineer and approved by
the City Engineer.
e. Grading necessary for roadways, public facilities, drainage improvements, open
space recreational facilities and their supportive uses should be sensitive to the
existing topography. Grading techniques should restore these areas to a natural
appearing state as much as possible.
f. Significant natural features such as visually sensitive ridgelines shown on
Appendix A, should be preserved or reinforced to the greatest extent possible
and incorporated into the development design.
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g. Grading on sites next to the BLM property/Eagle Regional Park, other regional
open space, and property boundaries adjacent to undeveloped lands should
blend with the characteristics of the existing landforms as much as possible.
4. Specific Grading and Siting Guidelines
a. Streets and Roadways
1) Street alignments should be designed to relate to natural or manufactured
topography. Roads running perpendicular to existing contours on steeper
slopes should be avoided.
Exhibit E - Road Grading
STRAIGHT SLOPE BANK 19
HEIGHTENS MONOTONY
OF ROADWAY LANDSCAPE
Conventional Road Grading
ROUNDED CONTOURS AND
UNDULATING SLOPES CREATE
A PLEASING ROADSCAPE-
Landform Road Grading
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2) Streets should move creatively on and around ridge forms. Ridgelines
and ridge tops should be visible occasionally above adjacent roadways.
Exhibit F illustrates how roads should integrate into the existing
topography
Exhibit F - Road Integration
THE EXISTING TERRAIN
& SHOULD RESTORE THE
AREAS TO ANATURAL
RIDGES & VALLEYS, IF POSSIBLE
----`-
--'�FLAT AREA CREATED
AT INTERSECTIONS —_
-PROPOSED ROADWAY
CONTOURS FOLLOW
EXISTING TOPOGRAPHY
TO MINIMIZE DISTURBAN
3) All grading within ACHD roadway prisms shall be built to ACHD
standards unless alternate street standards are approved by the City
and ACHD. Variations from dimensional standards, alternative cross
sections, alternative intersection spacing, multi -tiered divided streets
with sloping medians, reduced radius criteria, and increased street
gradients, and other alternative designs may be used to preserve
existing topography and minimize impacts of grading if approved by
ACHD, the City, and the applicable emergency service districts.
4) After the completion of grading, the timing of road construction and
paving shall be in accordance with ACHD standards and ITD
standards, if applicable.
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5) The width of the graded section shall extend three feet (T) beyond the
back of curb or edge of pavement on both the cut and fill sides of the
roadway to provide an adequate shoulder for health and safety. If a
sidewalk is attached to the curb, the graded section shall be increased
by the width of the sidewalk plus one foot (1') beyond the back of curb.
Detached sidewalks may be grade -separated from curbs so long as a
three foot (3) shoulder is maintained, otherwise, approval from the City
Engineer will be required.
6) All asphalt roads shall include an edge treatment such as, but not
limited to, vertical curb, modified vertical curb, rolled curb or ribbon
curb or compacted shoulder.
b. Development Pads/Lots
1) Lot lines shall be set at the top of a slope unless the down slope is a
common lot in which case the lot line may be set at the bottom or along
the slope when a drainage easement is in place on the down slope
common lot. Deviations must be approved on a case by case basis by the
Zoning Administrator.
2) When set at the top of a slope, property lines should generally be set back
a minimum of two feet (2') from the rounded hinge point at the top of any
manufactured slope unless grade -adaptive design techniques are
incorporated. See Exhibit G for an illustration of this concept.
Exhibit G - Lot Line at Top of Slope
131 Page
3) When the lot line is set at the bottom or along the slope a swale, ditch, or
other drainage collection system may be installed at the lot line to limit
cross lot drainage. Drainage collection may not be necessary if a
drainage easement is provided. Setbacks for structures shall be the same
as if the lot line were located at the top of the slope. For an illustration of
the concept, see Exhibit H.
Exhibit H - Lot Line Along Slope
c
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TYP. 1
2 Z
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cc
a
m
W J
PAD
POINT
� DRAINAGE
COLLECTION SYSTEM
4) Structures shall be set back a minimum of five feet (5') from any property
line adjacent to a slope or as set forth in section 1805.3 of the
International Building Code, whichever is greater. Alternate setbacks are
permitted as determined by the recommendation of a geotechnical
engineer in an approved soils report and with approval of the City
Engineer. For an illustration of this concept, see Exhibit I.
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Exhibit I - Minimum Slope Setback Example
The IBC states that the setback of a structure at the top of a slope should be at least H/3,
where H=the height of the slope, and the setback at the toe of the slope should be H/2. In
the example shown above the height of the slope is thirty feet (H=30'), thus, the setback at
the top of the slope is ten feet (H/3) and the setback at the bottom of the slope is fifteen feet
(H/2).
5) Grading within natural custom lots in the Southern and Southwestern
Planning Areas should generally be limited to pre -determined and defined
building envelopes. See Exhibit J for an example of a building envelope.
Exhibit J - Building Envelope Example
UNDISTURBED AREA BUILDING ENVELOPE
LIMIT OF DISTURBANCE
GRADED AREA:'-
LOT LINE
F
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6) Lot design should provide a pad with contoured transitional edges that
blend into existing topography. Exhibits K, L, and M show examples of
landform grading for lots with flat pads, grade adaptive pads, and a
building envelope.
Exhibit K - Flat Pad Design
PROPOSED ROUNDED
CONTOURS EMULATE
THE EXISTING TERRAIN
1 I
w
-� LOTUNE
ti= FIAT BUILDING PAD WITH
EDGES THAT TRANSITION INTO
SITE WALLS IF NEEDED EXISTING TOPOGRAPHY
11 2:1 MAXIMUM
SIDE YARD SLOPES
EXISTING TOPOGRAPHY
Exhibit L - Grade Adaptive Pad Design
PROPOSED ROUNDED
CONTOURS EMULATE
THE EXISTING TERRAIN
IFLn PAD
svsPurPAD
m PAD (,� \J
SITE WALLS IF NEEDED I SPLIT PAD TAKES UPGRADE
THROUGH THE STRUCTURE AND
2'1 MAXIMUM PRESERVES AND BLENDS THE HOME
SIDE YARD SLOPES INTO EXISTING TOPOGRAPHY.
EXISTING TOPOGRAPHY
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Exhibit M - Building Envelope Design
PROPOSED ROUNDED
CONTOURS EMULATE
THE EXISTING TERRAIN
{/y--a
LOT LINE _' '
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c. Structures
UNDISTURBED AREA
BUILDING ENVELOPE
-LIMITS OF DISTURBANCE
i I
1) Building forms, roof lines, and colors should be designed to help blend
structures with the natural terrain and limit sharp contrast.
2) Multi -level terracing of structures, should be considered on slopes. Grade
adaptive architecture can decrease grading impacts and maximize view
potential from residences. For examples of grade adaptive architecture,
see Exhibit N.
Exhibit N - Grade Adaptive Architecture
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1) Roof forms should follow the direction of the adjacent slope. Gable ends
should be limited next to the tops of slopes.
d. Retaining Walls
1) Retaining walls may be used to minimize grading.
2) A variety of wall types and surface materials should be used.
3) Retaining walls should not exceed eight feet (8') in height. If additional
retaining is needed, a second or third wall should be provided with a
minimum four foot (4') separation between walls. Slopes between walls
should not exceed 2:1 (50%). See Exhibit O for an example of a
permitted retaining wall.
4) Retaining walls should relate to the natural or manufactured topography
and variations in height and horizontal layout are encouraged. Retaining
walls shall be constructed only with materials included in the approved M3
Eagle development design criteria.
5) Post occupancy grading and wall construction shall comply with Eagle City
Code and approved M3 Eagle development design criteria.
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Exhibit O - Retaining Wall
EXISTING SLOPE
e. Driveways
1) Driveways, like roadways, should work with topography. Driveways are
an important design consideration and should relate to the environment
and blend into native or restored landscape.
f. Drainage
1) Drainage features should be incorporated in a natural manner into the
overall grading scheme to the extent feasible.
2) Concentrated run-off should be directed away from steep hillside areas
and onto streets or drainage devices.
3) A Storm Water Pollution Prevention Plan shall be completed for each
development phase in accordance with Idaho Department of
Environmental Quality (IDEQ) and Environmental Protection Agency
(EPA) standards.
g. Compaction
1) All fill placed on ground with gradients steeper than 5:1 shall be keyed into
the slope. Specific criteria for key dimensions shall be set forth in the site
specific soils report.
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2) Fill areas shall be prepared by removing organic material such as
vegetation and rubbish and any other material which is determined by the
geotechnical engineer to be detrimental to proper compaction or otherwise
not conducive to stability. No rock or similar irreducible material with a
maximum dimension greater than eight inches (8") shall be used as fill
material in fills that are intended to provide structural strength.
3) Fills shall be compacted to at least ninety five percent (95%) of maximum
density, as determined by AASHTO T99 and ASTM D698.
5. Landscape/Erosion Control
a. A Slope Stabilization and Re -Vegetation plan shall be submitted with each
grading plan and shall include a complete description of the existing vegetation,
the vegetation to be removed and the method of disposal. The plan shall also
include a general description of the vegetation to be planted or slope stabilization
measures to be installed along with the identification of those areas on the plan.
All Storm Water Pollution Prevention (SWPP) and National Pollution Discharge
Elimination System (NPDES) regulations shall be followed, as required by the
Environmental Protection Agency (EPA) and/or ACHD.
MM will-
191111111
- - • •
-
c. All graded areas should be re -vegetated for erosion control and visual
enhancement.
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d. Re -vegetation of graded slopes should take place in the first planting season
following the completion of construction.
e. Re -vegetation on graded slopes should consist of plant species that are
indigenous to or compatible with the local environment and shall comply with the
landscape standards set forth in the M3 Eagle Design Guidelines.
f. Re -vegetation on graded slopes may or may not include irrigation.
g. Drought tolerant and fire resistant material shall be selected whenever feasible
and in accordance with an approved wildfire management plan and shall comply
with the landscape standards set forth in the M3 Eagle Design Guidelines.
h. Storm water runoff measures shall be in place to prevent large movements of
sedimentation.
i. The developer shall be fully responsible for any destruction of native vegetation
proposed for retention. He shall carry the responsibility both for his own
employees and for all subcontractors from the first day of construction until the
notice of termination is filed. The developer shall be responsible for replacing
such destroyed vegetation.
j. The owner of any private property on which grading or other work has been
performed pursuant to a grading plan approved or a building permit granted
under the provisions of these standards shall not remove erosion prevention
devices, retaining walls, drainage structures or means, and other protective
devices, plantings and ground cover that have been installed or completed
without consent from the responsible party.
GRADING PLAN REQUIREMENTS, REVIEW, and APPROVAL
1. Engineering Reports
The developer shall retain a project engineer(s) (a professional engineer licensed in
the State of Idaho, otherwise known as the engineer of record and may include
various areas of expertise, i.e. structural or geotechnical, engineer(s)) to provide the
following information for any proposed hillside development. These reports shall be
submitted to the City for review and approval prior to, or along with the grading plans
or preliminary plat, whichever comes first.
a. Soils Report
A soils engineering report shall include data regarding the nature, distribution and
strength of existing soils, conclusions and recommendations for grading
procedures, design criteria for corrective measures, and opinions and
recommendations covering the adequacy of sites to be developed. If areas are
211Page
found to have soils hazards, the soils report shall recommend measures to
mitigate those hazards. If no mitigation is recommended, that area should be
deemed unbuildable. The report shall also contain a recommendation that the
project engineer review the grading plan in order to minimize any conflicts
between the plans and recommendations presented in the report.
The project engineer shall conduct periodic inspections during and after
construction in order to verify actual conditions and substantiate initial
recommendations. Due to the varying extent and duration of grading operations,
the frequency of inspections shall be determined by the City Engineer at the time
of grading plan approval and will be enforced as a condition of such approval.
The final graded condition shall then be certified by the project engineer within
two (2) weeks of the completion of grading operations. If conditions during
construction are found to be substantially different from those stated in the report,
the project engineer shall provide a summary of findings to the City along with
appropriate remediation measures and timing of such measures.
b. Geology Report
A geology report shall include an adequate description of site geology and an
evaluation of the relationship between the proposed development and the
underlying geology and recommendations for remedial measures. If areas are
found to have geologic hazards, the geology report shall recommend measures
to mitigate those hazards. If no mitigation is recommended, that area should be
deemed unbuildable. The report shall also contain a recommendation that a
project engineer review the grading plans in order to minimize any conflicts
between the plans and recommendations presented in the report.
A project engineer shall conduct periodic inspections during and after
construction in order to verify actual conditions and substantiate initial
recommendations. Due to the varying extent and duration of grading operations,
the frequency of inspections shall be determined by the City Engineer at the time
of grading plan approval and will be enforced as a condition of such approval.
The final graded conditions shall then be certified by the project engineer within
two (2) weeks of the completion of grading. If conditions during construction are
found to be substantially different from those stated in the report, the project
engineer shall provide a summary of findings to the City along with appropriate
remediation measures and timing of such measures.
c. Hydrology Report
A hydrology report shall include an adequate description of the hydrology,
conclusions and recommendations regarding the effect of hydrologic conditions
on the proposed development, and opinions and recommendations covering the
adequacy of sites to be developed. If areas are found to have hydrology hazards,
the hydrology report shall recommend measures to mitigate those hazards. If no
mitigation is recommended, that area should be deemed unbuildable.
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2. Grading Plans
a. Mass Grading Plan
Due to the topography of the site and scale of the project, there will be significant
grading operations that involve moving large volumes of material. Mass grading
at an early stage will allow for earthwork balancing, stockpiling, creation of large
pads intended to be further subdivided, otherwise known as superpads,
individual pads, and grading for roadways and drainage on a large scale, rather
than on a parcel by parcel basis, to provide for better integration of future
development into existing landforms. Although mass grading plans are
generated with the best soil and design information available, there can be many
factors during grading operations that can significantly alter the final grades. This
initial step allows for adjustments and refinements to the final plans without
significant redesign after detailed plan approvals.
A mass grading plan may be submitted and approved prior to submittal of a
preliminary plat and shall include the following information:
1) Proposed elevations and contours to be achieved by the grading,
identification of cut and fill slopes, overall earthwork quantities, potential
stockpile locations, temporary haul routes, and water tank locations for
dust suppression.
2) Approximate locations of all roads, surface and subsurface drainage
devices, walls, lakes/dams, sediment basins, storage reservoirs and other
pertinent structures to be constructed if sufficient detail is available at the
time of submittal.
3) An erosion and sediment control plan which meets the minimum
requirements of the EPA NPDES Permit.
4) A slope stabilization and re -vegetation plan described in the Grading and
Development Criteria, Section 5.a.
5) Phasing and estimated timing of each construction phase, if applicable.
b. Mass Grading Permit
A mass grading permit is an approval of the mass grading plan application by the
City and shall serve as consent to begin mass grading. A mass grading permit
can be in the form of a letter, or a signed mass grading plan. Mass grading
operations are subject to the following criteria:
231 Page
1) A mass grading permit is required prior to any on -site or off -site grading
activity associated with non-agricultural development of the property prior
to submittal of a preliminary plat.
2) Mass grading permits shall be issued by City staff only after the City
Engineer has approved a mass grading plan.
3) There are no size or quantity restrictions that would limit the applicability of
a mass grading permit.
rum. RW
5)4No plat or improvement plan approvals are necessary prior to
issuance of a mass grading permit.
&)5L An approved mass grading plan, a mass grading permit, or a
finished mass grading operation does not constitute, and is independent
of, plat approval and improvement plans approval.
7�6) Due to the fluid nature of mass grading operations, changes may
occur on a regular basis due to unanticipated field and soil conditions.
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Most changes are minor or not substantial and will not require submission
and approval of revised plans or cessation of operations. If a substantial
modification to the approved plans is necessary, the developer shall
submit the revised plans to the City for review and approval. A
substantial modification shall be deemed to be (i) a change in the area to
be graded by more than 20% (ii) a change in grading that will cause a
substantial change in surface water flows so as to require modification to
drainage structures, or (iii) a variation of 20% in excess of the total yards
of cut and fill approved within any one phase.
7) In the event that the City determines that the developer is in violation of
the provisions of the mass grading permit, or the improvements shown in
the grading plan, including but not limited to: grading beyond a permitted
phase, expiration of the financial assurances, grading outside of the limits
of permitted construction, using haul roads not shown on the Maul --read
plan, eFstockpiling dirt outside of the boundaries of the area permitted for
grading, or is in violation of the provisions of its state or federal permit
relating to the grading operation, the City shall notify the developer in
writing of the specific violations. The City and the developer shall meet as
soon as practicable after the notice of violation is given to the developer to
discuss a remedy and to determine a timeline within which to effectuate
such a remedy. In the event the noticed violation cannot reasonably be
remediated within ten (10) business days, is an imminent threat to public
health and safety, or as otherwise required by state law, the City may: (i)
suspend grading activities until such time as a written agreement for
remediation is reached with the developer or a new grading plan and
permit are approved, and/or (ii) notify the state or federal agencies that
have issued a permit related to such grading activity of such violations.
Upon reaching sushan agreement on the correction of the violation with
the City, or obtaining approval from the applicable state and federal
agencies if required, if the GOW Ret0foes S^h agenGmesthe developer may
resume grading activities.
If the City believes that the developer is in violation of its permit(s) related
to the grading operation or its grading plan for a portion of the work or a
substantial modification to approved plans is necessary for that portion of
work, grading operations may continue on the remainder of the work so
long as such operations are still in compliance with the approved grading
plan and permit(s), unless the City determines continued grading may
jeopardize public health and safety.
8) A violation of an approved gradinq permit/pan will not have an effect on
other existing eF faiaregrading permits/plans being conducted by the
developer in violation. Violations of an approved grading permit/plan will
not have an effect on existing or future grading permit/plans of other
developers operating within M3 Eagle.
251Page
9) Prior to beginning of mass grading operations, the developer shall provide
an infrastructure assurance, i.e. a bond or a letter of credit in accordance
with Section 2.9 of the Development Agreement, to ensure that
construction will be completed or the property will be stabilized in the
event that the work is unable to be completed.
The engineer of record shall provide certification of the percentage of
completion of the grading work to the City for review and approval on a
monthly basis or at agreed upon milestones with a minimum of once per
quarter during the course of grading operations, as defined in the mass
grading permit conditions. Within thirty (30) days of City receipt, the
construction infrastructure assurance shall be reduced accordingly, per
Section 2.9 of the Development Agreement, to reflect the percentage of
approved grading work.
The developer shall deliver a confirmation letter from the project engineer
stating that all construction is complete. The City may conduct an
additional inspection to verify the project engineer's findings. The
developer shall also submit record drawings of the mass grading plans to
the City that comply with the standards listed below. Record drawings
shall be submitted within two (2) weeks of the submittal of the
confirmation letter. After review of the confirmation letter and record
drawings have bp^n rereh&' by the City, the City Engineer shall issue a
letter describing whetherOf GOFREAaRGe statO44hat the grading work is
substantially complete in accordance has beeR MPlet^d-with the
261Page
approved plan(s) and whether the balance of the infrastructure monetary
assurance shall be released.
4,D)11 The record drawings package should consist of the following items:
a copy of the inspection log, a copy of the digital photographs, three (3)
copies of readable record drawings in hard copy, one digital copy in
AutoCAD format and one digital copy in pdf format, and all test results,
certified by the project engineer.
c. Final Grading Plan
A final grading plan shall be submitted after submittal of a preliminary plat and
prior to or concurrently with improvement plans. A mass grading plan is not
required prior to final grading plan approval. A final grading plan shall contain the
following information:
1) Limiting dimensions, residential and commercial building lot pad
elevations (if applicable), proposed street and slope grades, retaining wall
details and cross sections, finished contours for open space areas/trails,
etc
2) Detailed plans and locations of all surface and subsurface drainage
devices, including walls, dams, sediment basins, storage reservoirs and
other protective devices to be constructed
3) Phasing, if applicable, and a schedule showing when each phase of the
work will be completed, including a plan that indicates areas to be
disturbed during each stage together with estimated starting and
completion dates. In no event shall the existing natural vegetative ground
cover be destroyed, removed or disturbed more than fifteen (15) days
prior to grading
4) An erosion and sediment control plan which meets the minimum
requirements of an EPA NPDES Permit.
5) A slope stabilization and re -vegetation plan described in the Grading and
Development Criteria, Section 5.a.
d. Final Grading Permit
A final grading permit is an approval of the final grading plan application by the
City and serves as consent to begin final grading. A final grading permit can be
in the form of a letter or a signed final grading plan. Final grading operations are
subject to the following criteria:
271Page
1) A grading permit is required prior to any on or off -site grading activity
associated with non-agricultural development of the property.
2) A final grading permit may be issued any time after preliminary plat
submittal.
3) A final grading plan approval is required prior to recordation of a final plat
for individual buildable lots regardless of whether a mass grading plan has
been approved. A final grading plan approval is not required prior to
recordation of a final plat for a lot for parcel that is intended to be further
subdivided.
4) Final grading plan approval is required prior to the issuance of any
building permits.
5)If a substantial modification to approved plans is necessary as defined in
paragraph b.8), above, the plans shall be submitted to the City for review
and approval. Grading operations may continue on the remainder of the
work so long as such operations are in compliance with the approved
grading plan and permit, unless the City determines continued grading
operations may jeopardize public health and safety or otherwise violates
existing state law.
5)6) A final grading permit shall include a requirement that the project
engineer inspect the completed work for compliance with the final grading
plan and submit a confirmation letter to the City stating that all
construction is complete. The City may conduct an additional inspection
to verify the project engineer's findings. The developer shall also submit
record drawings of the mass grading plans to the City that comply with the
standards listed below. Record Drawings of grading plans shall be
submitted to the City within two (2) weeks of the submittal of the fir letter
of compliance.
6)77 The record drawings package should consist of the following items:
a copy of the inspection log, a copy of the digital photographs, three (3)
copies of readable record drawings in hard copy, one digital copy in
AutoCAD format and one digital copy in pdf format, and all test results,
certified by the project engineer.
3. Grading Plan Review Process
a. The developer shall submit an application and grading plan to the City Zoning
Administrator for review that includes the following:
1) A written application requesting approval of the grading plan;
28IPage
2) Six (6) copies of the grading plan drawn in accordance with the
requirements set forth above for each grading plan type. Each copy of the
grading plan shall be on good quality paper, shall have the dimensions of
not less than twenty four inches by thirty six inches (24" x 36"), shall be
drawn to a scale of not less than one inch to one hundred feet (1" = 100'),
shall show the drafting date, and shall indicate thereon, by arrow, the
generally northerly direction.
b. The Administrator shall notify the developer within thirty (30) days from the date
of receipt of the application as to the general conformance of the grading plan to
these standards and, if necessary, supply comments describing any concerns
and desired modifications.
c. The Administrator or developer may request a meeting with either party and the
City Engineer to discuss comments and possible modification to the plan. Such
meeting shall be held within fourteen (14) days of receipt of the request.
d. The developer shall resubmit an updated grading plan within sixty (60) days after
the receipt of comments or the comment review meeting, whichever comes later.
e. Timing of subsequent submittals and reviews shall follow the timing outlined
above or as otherwise agreed to by both the Administrator and the developer.
f. The city shall approve, approve with conditions, or deny the plans.
g. In the event that the Administrator denies the plans or developer is not agreeable
to the attached conditions, developer may appeal the decision to the City
Council. Such appeal shall follow the appeals process outlined in Title 8-7-4 of
Eagle City Code.
291Page
Appendices
Appendix A - Existing Landforms
301Pa2e
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Appendix B - Existing Slopes
311Page
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Appendix D - Visual Sensitivity Analysis
331Page
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