HomeMy WebLinkAbout1999/04/28 - Agenda Packet - WorkshopCITY OF RANCHO CUCAMONGA
PLANNING COMMISSION
WORKSHOP AGENDA
WEDNESDAY
APRIL 28, 1999
Rancho Cucamonga Civic Center
Rains Room
10500 Civic Center Drive
Rancho Cucamonga, California
8:00 PM
I. CALL TO ORDER
Roll Call
Chairman McNiel __ Vice Chairman Macias __
Com. Mannedno __ Com, Stewad __ Corn. Tolstoy__
II. NEW BUSINESS
PRE-APPLICATION REVIEW 99-04 - GRABIEL - Review of grading
concepts for 21 lots within approved Tentative Tract 10035 on 15.7
acres of land in the Low Residential District (2-4 dwelling units per
acre) located on Camino Predera south of Red Hill Country Club Drive
- APN: 207-641-01 thru 10 and 207-631-01 thru 11.
PRE-APPLICATION REVIEW 99-05 - KAPLAN - The proposed
development of a 125-unit senior housing, 100-unit assisted living, and
25,000 square foot medical office on a 13 acre site in the Industrial
Park District (Subarea 7) of the Industrial Area Specific Plan, located
at the southwest corner of Foothill Boulevard and Elm Avenue -
APN: 208-352-63 through 69.
III. PUBLIC COMMENTS
This is the time and place forthe genera/public to address the Commission. Items
to be discussed here are those which do not already appear on this agenda.
IV. COMMISSION BUSINESS
QUARTERLY DISCUSSION AND REVIEW OF DESIGN REVIEW
COMMITTEE PROJECTS - A discussion and review of projects
considered by Design Review Committee during previous quarter.
V. ADJOURNMENT
The Planning Commission has adopted Administrative Regulations that set an
11:00p. m. adjournment time. If items go beyond that time, they shall be heard only
with the consent of the Commission.
I, Gall Sanchez, Planning Commission Secretary of the City of Rancho Cucamonga,
or my designee, hereby certify that a true, accurate copy of the foregoing agenda
was posted on April 22, 1999. a t least 72 hours pdor to the meeting per Governmen t
Code Section 54964.2 at 10500 Civic Center Drive, Rancho Cucamonga.
Page 2
VICINITY MAP
"k CITY HALL
CITY OF
RANCHO CUCAMONGA
CITY OF RANCHO CUCAMONGA
Community Development Department
10500 Civic Center Drive
Rancho Cucamonga, CA 91730
(909) 477-2750
UNIFORM
APPLICATION
Part 1
GENERAL REQUIREMENTS (Print or Type)
Name of Proposed Project
Lateran of Project '
Legal Descnptlon of Project (Assessors Parcel No)
Ap~jcanl's Nan~e
Address
Legal Owner'$ Name (ff d~ffetont from above)
(staff use only)
RELA TED FILES:
Address
Type of Review R~quostod ~loaso Chock All Applicable Boxes)
C.) Tontahve Parcel Mop
C,I Tenlative Tract Map
IJ Use Oo(errnlnahon
Vacat,on of Pubhc Rlght.of. Way or
Easornont
U Vanante
fJ Other'
Community' Plan Amendment
Conditional Use Permit
Conditional Use Permit
(Non-Conslruchen)
D~v/Doslgn Rovmw. Cornm/Indus
Day/Design Review. Resldonhal
Development Agreement
Development Oistncl Amendment
Erlterfalnrnent Permit
General Plan Amendment
O Hillside Development >4 DU
O Hillside Development ~ 4 OU
ca Landmark Alteration Porm,t
0 Lot Une Adjustment
FJ Minor Exception
X pre.Apphcatlon Royrow
CJ Specific Plan Amondmonl
PROJECT DESCRIPTION
Detailed Description o[ proposed Project (Attach Additional Sheets If Necessary)
OWNER CERTIFICATION
I codify that I am presently the legal owner of the above-described property. Further, I acknowledge the filing of Ibis
apph'cation and ce~ify thai all of the above information is true and correct. (if Iho undersigned is different from the legal
property owner, a letter of authorization must accompany this fornl.)
Pnnt Name and Title
I ',FfiNALIFORMS\COUNTER\UNbAPP.WPD
MACMAIN ASSOCIATES, LP
KIRKLAND OFFICE
4020 LAKIi WASHINGTON BOULEVARD NE, SUITE 103
KIRKLAND, WA 98033
TELEPHO,~'E (425) 822-1819 EXT 103
March 17, 1999
City ofRancho Cucamonga
Community Development Department
10500 Civic Center Drive
Rancho Cucamonga, CA 91730
Application for Pre-Application Review
21 lots located on Camino Predera
APN nos. 0207-641-0'I thru 10 and 0207-631-01 thru 11
Dear Sirs,
This letter is to certify that i am an authorized signatory for MacMain Associates, LP, the
owner of the above-noted property. I am hereby authorizing Hylton Grabiel Associates,
LLC to execute this application on behalf of the owner.
Youxs very Ixuly,
MACMAIN ASSOCIATES, LP
By: Polygon Lapits, Inc., its general partner
By: ~73 ~
G. F. Ledwith, its Vice President
PRE-APPLICATION REVIEW
DISCLAIMER STATEMENT
I hereby certify that I have read and understand the filing requirements and process for
Pre-Application Review and that I have voluntarily requested said review.
I hereby acknowledge that the Pre-Application Review does not relieve me from
preparation and submittal of any detailed plans, technical studies, or environmental
analysis required by the City of Rancho Cucamonga in connection with any subsequent
formal application for this project.
I acknowledge that the Planning Commission may require additional in~'ormation before
completing the Pre-Application Review.
I hereby acknowledge that the opinions and comments of the Planning Commission and/or
staff resulting from this Pre-Application Review are entirely non-binding on the City, the
Planning Commission, and/or staff as to subsequent further processing or development
of the project.
Signature
Date
Print Na~em~and Title
PREAPP - 4/96 Page 4 of 4
Hylton Grabiel Associates, LLC
26 Corporate Park, Suite 200
Irvtne, CA 92606
"Buena Vista Terrace", Rancho Cucatnonga
PROJECT DESCRIPTION
Buena Vista Terrace is comprised of lots I through 21, Tract Map 10035, recorded May 9, 1985.
The site is moderately sloped on the eastern portion (lots 10 - 21) and severely sloped on the
westerly portion (lots I - 9). Existing slopes are steeper than I to I (45 degrees) in several areas of
this section. All 21 lots are located on the south side ofCamino Predera and slope away from the
street. The average lot size is approximately 16,600 square feet.
Due to the extreme topography on the site, development of these lots has not been economically
feasible. The site is currently covered in weeds and is littered with trash. In addition, the site has
been the depository for uncontrolled soils dumping which has rendered it unstable and changed its
natural condition. There is also evidence of water channeling devices that have been blocked by this
dumping.
Several site plans have been proposed in the past, however, due to general economic conditions as
well as the prohibitive costs associated with creating finished lots, the site has not yet been improved.
We are currently in a very strong housing market that, with City support for our proposal, finally
makes it possible to replace the current blight with an attractive enclave of new homes.
DEVELOPMENT PROPOSAL
We believe the most logical and economic approach for developing this site is to create flat building
pads at street level. In order to create these pads and stabilize the fill onsite, we propose to utilize a
reinforced earth fill system. From the southerly property line (or the edge of the existing easement)
we will create a slope of I to 1 up to the flat pad elevation. The 1 to I slope maximizes the pad size,
allowing for construction of homes that are consistent with the existing neighborhood on Camino
Predera. This slope area will be benched appropriately to collect drainage and landscaped in a
manner that would surely enhance the entire area. The existing stand of trees along the southerly
property boundary also make a significant natural screen that makes it difficult, in any case, for
anyone situated south of the property to see the slopes. The landscaping which will be installed as
part of this grading project will stabilize the surface area of the slope, provide visual enhancement,
and consist of low maintenance plant materials. The formation of a maintenance association would
allow for the economic and effective maintenance of the slope areas.
The development being proposed will be consistent with the existing homes and will help enhance
and, ultimately, preserve property values in the neighborhood. Successful development of this site
will also result in the removal of a significant aesthetic and practical liability and see it improved with
a residential neighborhood that contributes to the economic viability of the city.
LANDFORM CONTOUR GRADING - NATURAL LOOKING SLOPES FROM
GEOSY'NTHETICS
MICHAEL T. PEAK
SUKUT CONSTRUCTION, INC., USA
DAVED L. THIELEN
GEOENGINEERS, INC., USA
RECEIVED
MAR ~. 5 1999
City of Rancho Cucamonga
p~anning Division
ABSTRACT
Geogrid reinforcement is being used by the hillside development industry to conslruct
natural appearing, undulating landforms. These landforms have included steepenexi 'slope sections
greater than 30 meters high with surface grades of up to 45 degrees. Additionally, all bill~ide
developments require some degr~ of corrective grading to mitigate severe engineering and
geotechnical constraints such as steep topography and ancient landslides. Conventional solutions,
including flatter slopes, soil cement, lime treatment, and battered retahiing systems can be
unecanomical and aesthetically unacceptable. The landform contour gnding concept, its use in
land planning, and its design and construction is described. A case history of landform contour
grading which included over 13,000,000 m3 of earthwork is presented describing a hillside
development project that is the largest slope reinforcement application in the world. Over
430,000 m2 of geogrid reinforcement materials were used 'to increase global and sarficial factors
of safety while at the same time improving the project's economic viability and environmental
acceptance.
INTRODUCTION
Large hillside land developments, such as those which have been occurring in Southern
California for the past 30 years or more, are ,nique. These developments require an enormous
amount of earthwork construction (grading) to produce enough useable land for an economically
viable project- It is not uncommon to have 30,000 m3 of graHing per housing ,mlt in high end
residential developments. The large grading quantifies are necessary because the land planner
and grading engineer must comply with a variety of city and county grading ordinances and
public works standards, which were formulated over the years to protect the public safety and
weftare. These codes usually specify a maximum slope gradient of 2H:IV (horizontal:vertical)
together with definitive specifications for street grades, widths, vertical curves and p_ clii_
In order to design a development having enough useable land that is not taken up by very
high 2H:IV (or flatter) slopes and ample street geomeuies, the land planner and exLMneer must
literally mass grade most of the site. In addition, almost all hillside land parcels contain many
geotechnical constraints that requixe extensive mitigation. These constraints include high ground
water tables, liquefiable sobs, compressible soils, creep zones, terrace deposits, organic stratun~
and expansive soils, adverse (dip slope) bedding planes, folds and flexure-slip surfaces, faults and
teetonic shear zones, open joInts and fractures, clay and gypsum seams, as well as ancient and
historic landslides. Conventional solutions for these problems .also create large volumes of
grading (correCtive grading) in the form of deep removals, overexcavation and recompaction,
shear keys and buttress ~ls. Massive retaining systems, shear pins, compaction grouting, soil
cement, lime treatment and other traditional geotechnical engineering solutions am sometimes
employed along with the massive earthwork requirements to provide the corrective solutions.
In recent years, hillside projects requiring extensive grading have been severely criticized
on environmental and aesthetic grounds. The standard 2H: 1V maximum terraced slope mandated
by building codes is criticized for having an artificial, regimented and urmamral appearance.
Several cities have responded to these concems by passing ordinances that restrict the heights and
lengths of slopes, the depth of cuts and fills, the allowable densities per acre and other measures
that further limit or prevent hillside land development-
In an effort to deal with the geotechnical, environmental, political and aesthetic cOnSlralnts
of large hillside developments, a new technology has emerged. The technology combines geogrid
reinforcement with state-of-the-art land planning and grading design. This new technology is
known as Landform Contour Grading. Landform Contour Grading was introduced to the hillside
development industry by Sukut Construction, Inc. in 1987 on a 35 meters high 1H:IV reinforced
buttress in San Diego (Chu & Poorround, 1989).
Although other types of geosynthetics, such as geonets and geotex~.les are also being used
in hillside developments as cost effective alternatives to conventional engineering and
consn'uction techniques, this paper will focus on Landform Contour Grading using gcog~d
reinforcement
LANDFORM CONTOUR GRADING
Landform Contour Grading is the construction of natural looking slopes that have
topographic contours and vegetation similar in appearance to the original and surrounding,
ungraded terrain. To achieve thi~ objective, slopes and contours are designed and constructed
with variable horizontal and vertical angles. To simulate natural slopes, while at the same time
creating enough useable land to produce an economically viable project, the land planner must
have the ability to incorporate steepened sections within the designed, variable slope. To ensure
beth global and surficial slope stability in most soils, tensile reinforcement must be included in
the design and construction of any portion of the variable slope that is steeper than approximately
2H: 1 V. Geogrids have proven to be the most practical and cost effective method of introducing
additional tensile strength to earth materials as will be specifically demonstrated in the case study
section of this paper.
Revegetafion of the finished, landform contour graded slopes with native and introduced
drought tolerant plant materials is mandatory in order to achieve the desired natural appearance.
Figure 1 depicts a typical Landform Contour Grading design using 2H:IV angles at the toe and
top of a variable slope that includes a 1H:IV reinforced section in the middle. Figure 1 also
includes an appropriate natural revegetafion specification for landform contour graded slopes.
Figure 2 shows a revegemted 21 meters high landform contour graded slope. The upper 9 meters
is a geogrid reinforced section.
Landform Contour Grading mitigates environmental and aesthetic concerns by reducing
the visual and physical impacts that result from conventional grading design and construction
methods. Figure 3 illustrates an actual and typical hillside design situation where a steep walled
canyon will be fried to construct a road. The conventional 2H:IV slope with surface drains
every 9 meters produces severe physical and visual impacts because of the much l&rger slope
when compared to the landform contour graded slope. Conversely, the landform contour grading
design significan~y reduces the amount of natural ground and vegetation that is physically
impacted by grading. Furthermore, reducing the area to be graded also produces substantial cost
savings by reducing the amount of clearing and grubbing, alhivinm and colluviurn removals,
canyon subdrains, embankment, surface drains and landscaping.
2F~ iv
REVEGETATEO SLOPE ADJACENT
TO UEVELOPHENT
Ih, lV GEOGRiD
REINFORCED SL0~
TRANSITION PLANTZNG/
NATURALFZED SLOPE
EXIST~G NATURAL
VEGETATION
EXISTING SLOPE ANO VECETATZON
Figure 1. LANDFORM CONTOUR GRADING, SHOWING REINFORCED SLOPE SECTION
AND REVEGETATION AT THE EDGE OF A DEVELOPMENT
The cost of purchasing and installing the geogrid reinforcement materials is usually minor
when compared to the direct, measurable construction cost savings. Indirect benefits can also
result from Landform Contour Grading such as the production of more useable land. The natural
appearance of Landform Contour Gr~dlng also tends to increase both the land values and
marketability of a development- Another important indirect benefit of Landform Contour
Grueling is that more reliable slope performance is possible. Properly selected geogrids provide
long-term durability of slopes even if the slopes are neglected and abused. For example, high
density polyethylene (HDPE) geogrids are relatively immune to chemical and biological
degradation and are indigestible to burrowing rodents. Geogrid reinfomed slopes can be designed
to resist erosion even ff they are saturated from overwatering, as frequendy happens.
DESIGN OF LANDFORM CONTOUR GRADED. SLOPES
The design process for landform contour graded slopes has only a few differences from
that used for conventional fill slopes. The primary difference is the treatment of the geogrid
reinforced section. The overall process beans with a geotechnical investigation which identifies
maximum safe angles and heights for ,nreinforced fill SlOpeS. In addition, prelirnillary
reinforcement layouts are identified for steeper slopes (typically up to 1H:IV). Based on the
results of the geotechnical investigation, the land planner and civil e,~neer incorporate multiple
slope gradients and slope contouring into the master plan for the development- The reinforced
and compound slope sections are analyzed for specific geogrid requirements. The slope
reinforcement layout, detail~ and si~ecifications become part of the construction documents.
In areas requiring reinforcement, the goal of a comprehensive design is to determine the
type, length, and spacing of geogrids to achieve a safe slope. A safe slope is qnantified by the
factor of safety against sliding along some critical slip surface. Depending on the final slope
conditions, slopes may require only 'surficial reinfomement or both surlicial and global
reinforcement-
A significant amount of information has been published which describes the analysis of
slopes reinforced with geogrids, the mechanisms of geogrid. reinforcement, and the field and
hboratory base used to develop design methods (Chriswpher et al. 1990 and Mitchell and Viilet,
1987). Consequently, the following discussion is an overview of the design process.
The required design parameters for reinforced slope sections are: 1) the slope geometry,
2) the soil strength properties of the fill and h-place soils, 3) the tensile and soil interaction
properties of the geogrid, and 4) the performance criteria of the slope. The performance criteria
are usually defined by acceptable safety factors and long-term durability of the geogrids. Current
state-of-the-practice designs utiliTe soil properdes and reinforcement properdes developed by
extensive laboratory testing. A discussion of important properdes for geog~ds is p~csentcd in
the Case Study section.
Figure 2. REVEGETATED 21 METER HIGH LANDFORM CONTOUR GRADED SLOPE
HAVING A Ill:IV REIN'FORCED SECTION IN THE UPPER 9 METERS.
Figure 3. LANDFOI~M GRADING USED TO REDUCE TI-[E SIZE OF A CANYON FILL
Analyses of safety factors (slope stability) are generally accomplished by computer.
Sound geotechnical engineering Practice is utiliTed to select the type of analyses required for each
.application. Failures of slopes can occur by several mechanisms: 1) rotational slides generally
modeRed as cylindrical surfaces and analyzed by a "Simplified Bishop" type equation, 2) wedge
failures and general failure surfaces modelled by one or more linear surfaces and analyzed by
a "Janbu" type method, and 3) long transla~onal slides modelled as infinite slopes. These
analyses generally result in a computed factor of safety, which is the ratio of the forces (or
moments) resisting failure and those forces (or moments) tending to cause shear failure along the
assum~xt slip surface.
Many slope stability computer programs have incorporated geogrid reinforcement The
geogrid reinforcement is considered to be an additional resisting force where it crosses the slip
surface. The design tensile capacity is the lesser of the allowable tensile strength of the geogrid
and pullout resistance of the geogrid where it is embedded behind the failure surface.
Slope sections requiring reinforcement should be analyzed for both surficial and global
stability. Surficial stability is usually modelled as a long, downslope translational slip plane of
some finite depth, usually less than 1.3 meters. The soft above the slip surface is assumed to be
saturated, and an adequate spacing and length of surficial or secondary geogrids is specified to
r~sist failure. A method of analyzing surficial stability of reinfomed slopes in presented by
Thielen and Coilin (1993)..
In addition to stability issues, surface erosion should be considered. Surface erosion is the
degradation of the slope face by external forces such as flowing water, blowing winds, and
trafficking or boring by anirnal~, These conditions can be exacerbated by seasonal wetting and
drying cycles that may loosen the outer several centimeters of surface soils. Current practice for
reinforced slopes is the same as for unreinforced; that is. to vegetate the slope with indigenous
plant species that will resist erosion and maintain consistent soil moisture.
Although internal stability and erosion should be ueated separately dudrig design, they can
affect one another. Slope face erosion can accelerate surface water intrusion, resulting in a
saturated condition. A saturated condition at the slope face results in reduced surficial stability.
Conversely, geogrids placed in the outor several meters of the slope for surficial stability can
enhance erosion control by preventing the formation of surface rills.
Surficial reinforcement of the slope face of otherwise stable fills is finding increased
acceptance on large hillside grading projects. Sufficial reinforcement of fill slopes with geogrids
is being used by some prudent Southem California hillside land developers to reduce their
exposure to the long-term liabilities associated with slope failures. Some geotechnical consultants
and engineering contractors, as part of theix risk management program, are encoura~ng their
clients to sufficially reinforce all of their fill slopes.
CASE STUDY - SPANISH HILLS GOLF AND COUNTRY CLUB
The Spanjsh ~lls Goff and Country Club project is located in the City of Canmrillo,
County of Ventura, California. It is situated on 1,546,000 m2 of hillside terrain and includes an
18 hole chafnpionship goff course, a 3,534 m2 club house, 151 estate lots and 2 condominium
sites. The grading improvements were starred in November of 1990 and wen: completed in
November of 1992.
The project presented a tremendous grading challenge due to an 80 meters high hillside
dissected by I 1 steep canyons. Adding to that challenge were fault zones and associated teetonic
features that traversed the site as well as a bedrock structure that contained out-of slope bedding
planes with weak seams. The original grading plan for this project utilized very high
conventional 2H:iV perimeter slopes with horizontal terrace drains every 9 meters vertically.
In addition, most of the perimeter slopes would have required large shear keys of up to 25 meters
deep and over 65 meters wide. Crib-type retaining walls were proposed at numerous locations
within these slopes in order to yield enough useable land for an economically viable project
This original plan was rejected because of political, economic, aesthetic and geotechnical
considerations. The City and adjacent land owners would have objected to the ,nnatural
appearance of high, conventional slopes and Walls. Furthermore, the regimented 'appearance of
these slopes would have created a marketing and public relations problem for the project. Lastly,
the geotechnical consultant discovered that the slopes with the crib w~ll~ did not produce
acceptable factors of safety.
Conventional engineering solutions to these problems such as flatter slopes, larger walls,
and soft-cement or lime-lxeated bu~esses were not feasible. Flatter slopes would have eliminated
32 estate lots or required the purchase of a tremendous amount of off-site acreage. Larger wall~
would have been unsigh~y and uneconomical. Soft-cement or lime-treaunent was not only
uneconomical but would have made it difficult to landscape the slopes.
Landform Contour Grading proved to be the only viable solution. A total of 29 reinforced
slopes were contoured both horizon(Mly and vertically. A maximum slope gradient of 1H:IV
was used. The highest compound slope, having variable gradients of between 5H:IV and 1H:IV
was 41 meters high. The highest 1H:IV slope section was 20 meters high and 550 meters in
length. All slope sections steeper than 2H:IV u~liT. ed p~nmxy reinforcement layers of EDPE
geogrids. Intermediate reinforcement consisted of layers of polypropylene geogrids. All of the
walls were eliminated by the reinforced slopes.
Landform Contour Grading dramatically reduced the environmental and visual impacts of
the perimeter slopes. Also, many of the project's interior slopes, including those surrounding the
goff course, u~liTed steep reinforced slope sections to p. roduce aesthetically pleasing final grades.
The ability to produce steep slopes also provided an economic solution to the adverse
bedding plane problems. By placing the 1H:IV sections neax the toes of the fills that butzressed
agMnst the bedding planes, the sizes of the shear keys were reduced dramatically. This is due
to the higher shear resistance in the shear keys that was obtained by increasing the height of the
fills over the shear keys. The largest shear key on the project averaged 15 meters dee and 45
meters wide. It was estimated that Landform Contour Grading saved oi, er 3,000,000 m~Pof shear
key construction.
Design of the Reinforced Sections and Selection of Geowrids
A typical analysis cross section through a reinforced project slope is shown in Figure 4.
The section shows the slope geometry, the geogrid elevations and lengths, the soil properties, and
information about the design slip surface. Two types of analyses were conducted to detemine
the type, spacing, and length of geogricls required for the slopes: circular global stability analysis
and surficial stability analysis. These analyses were conducted following the guidelines discussed
in the previous section on design. In addition, finite element analyses were conducted to evaluate
the deformation of the largest reinforced slope (Chandra and Lay, 1992 and Bray et. al., 1992).
180
120
100
00
'CRITICAL CIRCLE OATA'
CENTER AT (315,3~5)
RADIUS.- 248
SAFETY FACTOR - 1.51
(I'q8,191) GEOGRID LEGEND=
UXIGee HDPE GEOGRID
UX1500 HDPE GEOGRID
1 (189,178)
~ (197,170)
'~x BOTTOH GRID AT EL. 195
ALL SOILS
~ - 123 PCF 1Ft - 0.305 m
~ - 30 DEGREES I psF - 47.88 N/m2
C - 130 PSF 1 pcf 157.1 N/m3
Figure 4. TYPICAL COMPUTER MODEL CROSS SECTION FOR A CONTOUR
GRADED SLOPE AT SPANISH HIt .1S
Geogrids were required to meet the following selection criteria: I) they had to be capable
of developing the required long-term allowable design tenslie strength, 2) they had to have high
soil interaction to develop pullout resistance over a reasonable length, 3) they had to have long-
term durability in order to meet the design assumptions over the life of the slopes, 4) they had
to resist construction induced clamage, and 5) they had to be suitable for the large scale, high
production earthwork operations that were employed on this project '
The specifications for the geogrids were based on testing standards established by both
ASTM and the Geosynthetic Research Institute CKoemer and Wilson-Fahmy, 1991). These
standards included evaluation of tensile strength, long-term creep, sol/interaction, chemical and
biological degradation, consla-uction induced damage, and susceptibility to ultraviolet light
The requirement that the geogrids be suitable for large-scale earthwork projects was very
important. The geogrids had to be capable of storage in staging areas for sustained periods of
time without losing strength. Furthermore, the geogrids had to be capable of withstanding traffic
by large rubber tired construction equipment operating directly on the geogrid. The geogrids had
to be stiff enough to retain their shape when compacted in ffils and not conform m local
irrtgularifies in the Fall surface. Based on the selection criteria, H:DPE primary geogrids and
polypropylene secondary geogrids were usexL A typical as-built section of a constructed slope
is shown in Figure 5.
T N I' N ~ / PINNED TO""'SLOPE
EL. 297, 18 F . L~ _O ........ ._._.' INND UNIAXIAL cOG ID N 2
EL. 292, 33 FT. LONG "2' ~", INTERMEDIATE BIAXIAL GEOGRiD-
......................
EL. 289. 40 FT, LONG __-"' ,~., (TYPICAL)
EL, 285, '~0 FT. LONG :Z. ~,,,
___-. __,___: .... :_.kX, TOP AND BOTTOM
LEGEND,
ELEVATIONS GIVEN IN FEET
1 rf - 0.305 m
I In - 2.5'~ cm
5. CONSTRUCTION DETAIL OF CONTOUR GRADED SLOPE FOR SPANISH HTI .LS
Conslruc~on of the Landform Contour Graded Slopes
The most complicated and critical component of constructing the landform contour graded
slopes and shear keys on this project was not the handling or placement of the geogrid materials,
it was the earthwork logistics planning and design. To control potential catastrophic failures in
the very high and steep temporary construction slopes associated With corrective grading, the
earthwork operations had to be carefully phased. To control earthwork construction costs and
to maintain production when placing the geogrids, the construction equipment had to be
temporarily 'assigned to other sectors of the job. ff reinforced fffi areas were not available,
sections of the aareinforced fills were consumeted adj~icent to the reinforcement materials
placement zone in order to keep the equipment working. In severely restricted areas, temporary
waiting periods were sometimes unavoidable and had to be factored into the earthwork costs and
logistics design.
The specific construction methods for using HI)PE geogrids to construct landform contour
graded slopes at the Spanish Flilk project were as follows:
1) After the geogrids had been delivered to the job site storage area by the manufacturer,
they were unrolled and pre-cut to specified lengths. The lengths and .placement of a
specific grade of geogrid was controlled by a geogrid schedule ("cut sheet") developed by
the contractor from the appmved minfomement plans.
2) After the geogrids had been pre-cut, they were re-rolled, marked and stacked in order
for delivery to the work area. Two laborers were required for pre-cutfing.
3) The geogrids were delivered to the work area on a flat bed truck and rolled out in the
predetermined order onto the prepared, tested and approved subgrade. This operation
usually required 2 or 3 laborers.
4) Fill materials were dumped at the work area by 30 m3 wheel tractor-scrapers
(scrapers). The scrapers were not allowed to turn or exceed 16 kilometers per hour while
traveling directly on the geogrids. This is illustrated in Figure 6. Whenever possible, the
fill materials were pre-watered and mixed in the excavation area before delivery to the
reinforcement work zone..
5) Each lift of fill was spread in 15 to 20 centimeter thick lifts, mixed and compacted by
wheel tractors (rubber-tired dozers), motor graders, u-ack-type lxactors (dozers) and
scrapers to a minimum of 90% of the maximum density as determined in accorcla~ce with
ASTM D1557 ['Modified Proctor). Compaction tests were required for every 382 m3.
Tracked-type equipment was not allowed to operate Without a minimum of 0.3 meters of
soil cover on the geogrids. Figure 7 shows geogrids in place and fill being spread over
them.
Figure 6. SCRAI6ER DUMPING FILL SOIL ONTO GEOGR[DS
Figure 7. FILL SOIL SPREAD ONTO GEOGRIDS
6) Vertical elevations were checked every 0.6 meters in vertical height to insure that the
geogrids were being placed in accordance with the plans and specifications. Also,
frequent grade checking and staking were required to control the variable horizontal and
vertical angles of the landform contour graded slopes.
7) At the request of the City, a lightweight geogrid was placed directly on the face of the
reinforced slope sections. This geogrid was pinned to the slopes with landscape staples
or attached to the reinforcement geogrids using hogrings.
Figure 8 shows a completed landform contour graded slope, just prior to revegetation.
Figure 8. COMPLETED LANDFORM GRADED SLOPE PRIOR TO REVEGETATION
The corrective grading quantities on the project totaled 7,952,000 m3 including the
removal and recompaction of 1,835,000 m3 of alhvium, colluvium and other compressible
materials, 1,147,000 m3 of landslide removals. 1,912,000 m3 of overexcavation to prevent
excavation quantity was 5,200,000 rn . The combined grading quanuues were 13, , ·
In addition, over 40,000 m2 of nonwoven geotextiles were installed for subdrains in the canyon
f~ls, shear keys and bum'ess f'fils. In excess of 314,000 m2 of primary HDPE aniaxial geogrids
and over 117,000 m2 of secondary polypropylene biaxial geog~ds were used in the reinforcement
of shear keys, buttress ~is and the steep portions of the landform contour graded slopes.
Sukut Construction, Inc. was the earthwork design consultant, grading contrmztor and
general engineering construction manager. Midstam Engineering was the project Civil Engineer.
The project geoteckulcal consultant was Leighton and Associates, Inc. Design of the reinforced
slope sections was by Tensat Earth Technologies, Inc. and David Evans & Associates.
CONCLUSIONS
1. Land.form Contour Grading that incorporates geogfid reinforcement to produce a variety of
surface gradients can be utiliTed to construct natural-looking slopes. The variation of vertical as
well as horizontal grades in a development can produce an anXactive alternative to the traditional
uniform slope and terrace consU-uction.
2. Landform Contour Grading, incorporating steep slopes can mitigate the environmental and
visual impacts of hillside developments. This is most easily illustrated by a traditional canyon
fill that can be steepened to significantly reduce the amount of natural canyon that is impacted
by the fill.
3. Landform Contour Grading that u~liTes steep slopes can result in the benefit of more useable
land. The additional land can be used for development or open space.
4. Landform contour ~'aded slopes xeiaforced with geogrids can be a practical and cost effective
solution to engineering and geot~chnical problems on hillside land development projects.
Geogrids are being used to replace soil-cement and lime reinforcement materials for shear keys,
butlxess fills and steep slopes. These geogrid reinforced slopes can be revegetated. Steep
reinforced slopes can be utilized to provide additional weight over slope shear keys.
5. Landform Contour Grading projects that incorporate geogrid reinforcement can be constructed
with conventional equipment and easily modified construction methods.
ACKNOWLEDGEMENTS
The authors gratefully acknowledge the cooperation of Spanish IF_dis Development
Company and the editorial assistance of r .inch Adams, Mike Crawford, Maxgaret He~ey, Jerry
Pabbruwee, Mary Ann Schulte, Myron Sukut, and Steve Sukut, all with Sukut Construction, Inc.
REFERENCES
Christopher, B.R., Gi/l, S.A., Giroud, JP., .luran, I., Mitchell, J.IC, Schlosser, F. and
Dunuicliff, l., "Design and Construction Guidelines for Reinforced Soil Slructures -
Volume L" and Summary of Research - Volume II," Report No. H-IWA-RD-89-043,
Federal Highway Admini~Ixation, U.S. Depaxtment of Transportation, 1990.
Mitchell, J.K. and ViiieL W.C.B., "Reinforcement of Earth Slopes and Embankwaents',
National Coopera. tire Highway Research Program Report No. 290, Transportation
Research Board, Washington, DC, 1987.
Chu, D. and Poorwand, I., "Reinforcement of an Earthen Buttress with a Polymer
Geogrid", Proceedings of Geosynthetics '89 Conference, San 'Diego, Vol. 1, February
1989, p.p. 243-254.
Thielen,'D.L. and Coilin, J.G., "Geogrid Reirtforcement for Surficial Stability of Slopes",
Geosynthetics '93 Cortference, Vancouver, British Columbia, March 1993.
Bray, J.D., Boulanger, R.W., Chew, S.H., and Seed, R.B.,"Finite Element Analysis in
Geotechnical Engineering", Proceedings of the Ei~th National Conference on ComDulin~
in Civil Engineerins:, ASCE, Dallas, Texas, February 1992.
Chandra, D., and Lay, G., "Performance of a Geogrid Reinforced Slope on Compressible
Foundation", Proceedings of the 281h Symposium on En~ineerin~ Geoloev and
Geotechnical Engineering, Boise, Idaho, April, 1992.
Koerner, R.M. and Wilson-Fahmy, R.F, "Application of Geogrids - Volume 1 ", Report
No. FHWA-PA-91-003+90-17, Federal Highway Adminislxation, U.S. Department of
Transportation, Pennsylvania Depauhuent of Transportation, 1991.
L
RECEIVED
MAR 3 1 19cJ9
City of Rancho Cucamonga
Ranning Division
~111 D,,.D.,,,.PRELIMINARY GRADING
?;,.%%%~,,.,E. ,,ssoo,,,,-Es. ,_,_o
EXHIBIT
RANCHO CUCAMONGA, CALIFORNIA
1
April 5, 1999
City of Rancho Cucamonga
Community Development Department
10500 Civic Center Drive
Rancho Cucamonga, California 91730
RE: Assisted Living Facilities
Independent Living
Medical Office Building
Assisted Livinq Facilities
Assisted Living Facilities of America - ALFA, a national organization defines this type of
facility as a special combination of housing, personalized support services and health
care, designed to respond to scheduled needs of those who require help with the
activities of daily living (ADL).
For the past 4-5 years the entire U.S. has been in a boom market with reference to
assisted care, primarily because this type of facility creates a sense of belonging and
security to a very special segment of our society. namely the elderly. Keep in mind, the
average age of these men and women is 84-86, however this type of elderly housing is
in no way considered a nursing home and is not licensed as such.
Assisted living promotes maximum independence, choice, dignity and involvement with
family, neighbors, friends and the surrounding community. This style of housing lends
itself to non-institutional architecture, which in turn beautifies the community in which a
residential atmosphere is of prime importance to all who live there.
By and large, most cities are extremely proud to incorporate these residential
communities within their boundaries in order to have existing residents maintain their
homes where long lasting friendships have been developed.
Design · Build · Finance
Independent Livinq
This residential community starts at age 55-65 and continues to a stage in their lives
when assistance would be required in order to sustain everyday life. These facilities will
have all the amenities to offer retired couples or singles, such luxuries to include a
common dining room (along with individual kitchens in their apartment), tennis courts,
shuffle board, card rooms, pool, etc.
This residential community is better recognized as a feeder to the assisted living section.
It is of great importance to a widow or widower that they maintain the friendships they
have cultivated by not having to move to another geographic location but rather move
into another section of the same development.
Medical Office Buildinq
This facility is a great comfort to all residents since the medical office building is
contiguous to the residential community and will provide care and treatment for all
residents at a moment's notice. It should also be pointed out that the Heritage Hospital
is within 200 yards of the subject complex. At this time, the hospital contains 55 beds,
and is now in process of expanding to a total of 175 beds.
DESIGN REVIEW COMMITTEE ACTIVITIES '1/99 - 3/99
RESIDENTIAL
DEVELOPMENT REVIEW 97-23 (DESIGN REVIEW FOR TENTATIVE TRACT 13564)
STANDARD PACIFIC - The design review of the detailed site plan and building elevations for a
previously County approved residential subdivision of 182 lots on 117 acres of land in the Very
Low Residential District (less than 2 dwelling units per acre), located between Wardman Bullock
Road and the San Savaine Wash - APN: 226-082-30 and 58 through 63.
ENVIRONMENTAL ASSESSMENT AND TENTATIVE TRACT 15914 - ZOMMORODIAN - A
request to subdivide 11 acres of land into 9 single family lots in the Very Low Residential District
(up to 2 dwelling units per acre), located north of Hillside Road, between Archibald and Hermosa
Avenues - APN: 1074-071-20. Related file: Tree Removal Permit 98-26.
ENVIRONMENTAL ASSESSMENT AND VESTING TENTATIVE TRACT 15871 - LYON - The
proposed subdivision and design review of detailed site plan and elevations for 188 single family
lots on 62 acres of land in the Low-Medium Residential District (4-8 dwelling units per acre) of the
Victoria Community Plan, located southwest of Highland Avenue and future Day Creek Boulevard
-APN: 227-021-03 and 13.
DESIGN REVIEW 99-07 - GRIFFIN INDUSTRIES o The approval of the building elevations and
precise site plan (plotting) for 154 single family units for Phases 4, 5, 7, and 8 of Tract 15727.
ENVIRONMENTAL ASSESSMENT AND TENTATIVE TRACT 15948 - REGENT HOMES,
INC./BASELINE HOLDINGS, LLC - A residential subdivision of 40 single family lots on 10 acres
of land in the Low Medium Residential District (4-8 dwelling units per acre) within the Victoda
Community PLan, located at the south side of Base Line Road, approximately 650 feet west of
Etiwanda Avenue - APN: 227-171-003.
ITEM C
DESIGN REVIEW COMMITTEE ACTIVITIES 1/99 - 3/99
-2-
ENVIRONMENTAL ASSESSMENT AND TENTATIVE TRACT 15947 - REGENT HOMES, INC. -
A residential subdivision of 31 single family lots on 9.05 acres of land in the Low Medium
Residential District (4-8 dwelling units per acre) within the Etiwanda Specific Plan, located at the
south west comer of Base Line Road and Etiwanda Avenue - APN: 227-171-004.
ENVIRONMENTALASSESSMENT AND CONDITIONAL USE PERMIT 99-03 - REGENT HOMES,
INC. - A residential subdivision of 31 single family lots on 9.05 acres of land in the Low Medium
Residential Distdct (4-8 dwelling units per acre) within the Etiwanda Specific Plan, located at the
south west comer of Base Line Road and Etiwanda Avenue - APN: 227-171-004.
ENVIRONMENTAL ASSESSMENT AND DESIGN REVIEW 99-01 - WOODSIDE HOMES - The
design review of building elevations and detailed site plan for a previously approved tentative tract
map consisting of 36 single family lots on 21 acres of land in the Very Low Residential District (0 to
2 dwelling units per acre) of the Etiwanda Specific Plan, located at the southeast corner of
Etiwanda Avenue and Victoria Street - APN: 227-101- 4, 12, and 14.
COMMERCIAL
ENVIRONMENTAL ASSESSMENT AND CONDITIONAL USE PERMIT 98-30 - HOME DEPOT -
A request to construct a 220,669 square foot warehouse building on 12.4 acres of land in the
General Industrial designation (Subarea 8) of the Industrial Area Specific Plan, located at the
southeast comer of Arrow Route and Oakwood Place.
ENVIRONMENTAL ASSESSMENT AND CONDITIONAL USE PERMIT 98-25 - CHEVRON - A
request to demolish an existing Chevron service station and build a new 2, 167 square foot service
station/mini market, keeping the pump island and pump island canopy in-place, on 0.74 acres of
land in the Neighborhood Commercial District, located at 8687 Base Line Road -
APN: 207-022-041.
DESIGN REVIEW COMMITTEE ACTIVITIES 1/99 - 3/99
-3-
ENVIRONMENTAL ASSESSMENT AND CONDITIONAL USE PERMIT 98-31 - ARBY'S ~ A
request to modify a previously approved master plan and construct a 2,892 square foot fast-food
ddve-thru restaurant on 0.56 acres of land within an integrated 82-acre shopping center in the
Regional Related Commercial District of the Foothill Boulevard Specific Plan, located at the
southwest comer of Foothill Boulevard and Etiwanda Avenue - APN: 229-031-31.
ENVIRONMENTALASSESSMENTAND DEVELOPMENT REVIEW 99-05 - QUIKSET -A request
to review a master plan of development for a concrete and plastic products manufacturer for a
total of 161,400 square feet of office and manufacturing buildings on a 40-acre site within the
Heavy Industrial Distdct (Subarea 15) of the Industrial Area Specific Plan, located at 12167 Arrow
Route o APN: 229-121-15.
ENVIRONMENTAL ASSESSMENT AND CONDITIONAL USE PERMIT 98-32 -CARDLOCK
FUELS SYSTEM - The development of an unattended commercial fueling station consisting of a
3,210 square foot canopy and a 218 square foot utility building on 1.2 acres of land in the General
Industrial Distdct (Subarea 13) of the Industrial Area Specific Plan, located on the east side of
Chades Smith Avenue, north of San Madno Street - APN: 229-321-01. Related file: Preliminary
Review 98-10.
MASI PLAZA - Review of location for La Fourcede arch.
STEIN MART SIGN - Review of proposed wall sign for Stein Mart to be located at 10930 Foothill
Boulevard, Suite 130, in the Terra Vista Town Center Square.
DESIGN REVIEW COMMI'n'EE ACTIVITIES 1/99 - 3/99
-4-
INSTITUTIONAL
DESIGN REVIEW 98-32 - HERITAGE HOSPITAL (NURSING CARE FACILITY) - Design Review
approval for the construction of a new 56,896 square foot skilled nursing building and revision to
the Rancon Center Master Plan (Design Review 90-20). The Master Plan is located on the north
side of Civic Center Ddve between White Oak and Red Oak Streets.
ENVIRONMENTALASSESSMENTAND DEVELOPMENT REVIEW 99-04 - SILVERADO GROUP
- A request to build a 3-story, 34,860 square foot hotel as part of a master planned development
with three other retail buildings on 5 acres of land in Subarea 7 (Industrial Park) of the Industrial
Area Specific Plan located on the south side of Foothill Boulevard between Aspen and Spruce
Streets - APN: 208-352-82. Related File: Parcel Map 15282.
I:~FINAL~DLNGCOMM\01-99rev.wpd