Loading...
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