This year we had a very strong response from the membership with six excellent submittals. All the projects were outstanding, and we took pleasure in reviewing the great work our profession is doing. Thanks to Past President Gale Paddock, Director Joe Haro and President Craig Hill for their support and service on the Outstanding Project Award committee. This year all submittals met the requirements for the competition; which hasn’t always been the case. The committee selected two project winners, a medium and a large project, and an honorable mention this year.
2007-2008 Large Project Award Winner
The Bluebird Canyon Landslide
Geofirm/Stoney-Miller Consultants
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The June 1, 2005 Bluebird Canyon Landslide occurred on the northern flank of Bluebird Canyon in the City of Laguna Beach, California. The failure event was triggered by the rains of the 2004-2005 winter season.
The failure involved approximately seven acres. Overall the hillside translated horizontally approximately up to 85 feet in a south-southeast direction. By the time the initial movement had ceased, eleven residences were destroyed and eight residences were damaged. No persons were trapped or seriously injured. A total of 345 residences in eastern Bluebird Canyon were cut-off from services and temporarily uninhabitable. Residences down-canyon were at risk of flooding and mudflow.
Consulting services included communication with City, County, and State safety officials and services, State and Federal Emergency agencies, State and Federal Scientific agencies, and coordinated updates to the Victims, the Community, the City staff, and the Media. Conventional methods of surface and subsurface monitoring and investigation were employed on an accelerated schedule. The monitoring program began two days after the failure, with the Phase I design report submitted in 100 days. A series of slope inclinometer casings were installed within and around the failure to evaluate deep ground movement and allow relatively safe downhole logging beneath the failure. The findings from the boring exposures confirmed the inclinometer data and formed the basis for the failure geometry analyzed, including potential surfaces below the failure. Rupture surface geometry was 3D modeled in AutoCad.
The testing of ring and bulk samples included strength properties through direct and torsional ring shear testing, Engineering stability analyses were performed to stabilize the landslide headscarp, the drainage through the canyon, and the overall landslide mass. Strength parameters utilized for the analyses were based upon back-calculation, shear testing of onsite samples, as well as local experience in similar soils and engineering judgment. A 1.25 temporary factor of safety was targeted, while a 1.5 factor-of-safety was utilized for the permanent overall landslide stabilization. Repair logistics were designed to be staged and maintained within the confines of the failure site. Effective use of soil-cement was required to minimize excavation quantities and temporary stockpiling.
Repair of the 2005 Bluebird Canyon Landslide was implemented in two phases. The Phase I repair included placement of a storm drain and buttress fill in Bluebird Canyon, mitigating against retreat of the headscarp supporting Madison Place through the winter season, and winterizing the landslide by surficial remedial grading, drainage control, and debris fencing. Phase I work was performed 12 hours/day, 7 days/week. All of the Phase I repair objectives were completed in August 2006. The Phase II repair consisted of landslide removals and re-grading, construction of soil-cement shear keys, and installation of sub-drainage within the failed area. The Phase II repair restored the road and hillside to the original configuration within current grading code factors of safety, except as modified to satisfy current code requirements. All the remedial grading was completed in October 2007. As of this date the site has been geotechnically released for new residential construction. The following conclusions were drawn from the project:
- The landslide was a block-glide type failure that occurred in a formerly intact ridgeline. Our findings indicate that the slide is based at the top of a thick, tectonically disturbed layer of unoxidized claystone, and is structurally truncated to the north and west by ancient bedrock faults.
- The elevated groundwater pore pressures from the 2004-2005 seasons above-normal rainfall was the initiating factor responsible for the landslide.
- As the Geotechnical Consultants, we were asked to take a lead role in this disaster which involved supporting Emergency Personnel, Government Agencies, the Community, and the Victims with vital information based on limited data.
- The geotechnical design and construction pre-planning in AutoCad allowed the consultant to control site stability while maintaining the earthwork program within the limits of the confined site.
- Monitoring during excavation revealed marginal temporary stability. The temporary factor of safety during canyon slot-cutting was near 1.0 and almost 8 inches of landslide movement was recorded during the Phase I work, resulting from incomplete dewatering.
- Construction monitoring with slope inclinometers and wall survey targets was crucial in evaluating landslide movement and controlling the excavation sequencing. The landslide movement proved useful, however, in verifying the initial modeling of the landslide.
- The difficulties involved with earthwork logistics, excavation sequencing, and controlling landslide movement required constant coordination with the contracting team. Good communication and cooperation was essential in being able to complete the work in a safe and efficient manner.
Owner: City of Laguna Beach
Geotechnical Engineer: Geofirm/Stoney-Miller Consultants, Inc.
Civil Engineer: Fuscoe Engineering, Inc.
Structural Engineer: Earth Support Systems, Inc.
Construction Manager: Moote Group
Contractor: Bubalo Construction and Zamborelli Enterprises
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2007-2008 Medium Project Award Winner
Port of Long Beach Security Command and Control Center
Diaz Yourman & Associates
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The Port of Long Beach (POLB) Security Command and Control (SCCC) Building Project was located at a hydraulic fill area of the POLB. The site was underlain by several old buried rock dikes that consisted of quarry run rock (average grain size of 5 to 6 inches) with a layer of very hard armor rock (5 to 6 feet in size, 10 to 15 tons each). The composition and locations of the rock dikes were unknown. Only a 1970s geotechnical report provided guidance regarding the dikes. Potentially liquefiable soils were located below and behind the rock dikes. The SCCC structure included the first U.S. design of a critical structure foundation that will allow liquefiable soils flow though the foundation system while the structure and its foundation will remain intact and operational. This innovative geotechnical design allowed the building to be located at the best site based on numerous operational security constraints.
The design geotechnical engineer proposed foundation designs that consisted of either a series of rectangular cast-in-drilled hole (CIDH) piles or driven 24-inch precast octagonal piles. These designs were based on three-dimensional soil-structure interaction analyses. The POLB selected the driven pile option because of a recommendation by their reviewers and their experience in driving piles. The selected foundation alternative had five rows of piles, each row with eight individual 24-inch pre-cast octagonal piles. The final design consisted of 44 piles (four "extra" piles for specific load areas).
Because of the unusual site conditions and no well established analysis approach, several renown geotechnical engineers provided input to the project approach and design: Dr. Scott Ashford, University of California, San Diego, for loads of liquefiable flowing soils on vertical piles; Dr. Jonathan Bray of the University of California, Berkeley for soil parameters, general approach, and lateral spreading analysis; Dr. Peter Robinson, University of British Columbia for liquefaction potential analysis using the cone penetration test (CPT); and Dr. Leslie Youd, Brigham Young University, for lateral spreading. In addition, Dr. Arul Arumoli of Earth Mechanics, Inc. and Dr. Geoff Martin of the University of Southern California also reviewed the design for the POLB.
Before construction, a Becker hammer drill rig was used to pre-drill each of the 44 pile locations to reduce pile driving difficulties. However, the Becker hammer drill rig met drilling refusal at five locations, something that had not happened before in the POLB area. Two pile locations could be moved but three piles had to remain in those locations because of heavy building loads. At those locations, a special reverse air rotary drilling process was used to install a 30-inch diameter casing.
After the pre-drilling, the pile driving proceeded with the level of difficulty and effort anticipated in the design.
Preliminary geotechnical paper studies discovered that the selected project site likely contained previous rock dikes (one or more) that were buried several decades ago. The rock dikes probably consisted of quarry run rock that might be covered with very hard armor rock. The armor rock would make conventional geotechnical investigations and pile driving almost impossible.
Because of operational security constraints, the SCCC could not be moved to another site. Subsequent geotechnical field investigations were performed in stages using a variety of techniques to help identify the subsurface conditions. Seismic refraction and seismic reflection were used initially to try to locate and characterize the buried rock dikes. A CPT with a dummy tip was used to try to provide ground truth for the top of the buried rock dike(s). Later, rotary wash borings were used for conventional sampling in the fill soils behind the buried rock dikes. The conventional sampling included standard penetration test (SPT) values with energy measurements. To confirm the thickness of the rock dikes, Becker hammer borings were performed. The Becker hammer borings confirmed the locations and the thickness of the rock dikes but could not identify the armor rock.
DYA’s initial design report promoted site relocation. However, operational security constraints required the site be used. The design report was separated into two volumes. The initial report volume provided basic design criteria for the project civil and structural engineers and was suitable for City of Long Beach Building Department review. The second volume provided detailed description of the slope stability and deformation analysis as well as the results of several consultants.
Owner: Port of Long Beach
Geotechnical Engineer: Diaz Yourman & Associates
Civil Engineer: URS (Cash & Associates)
Structural Engineer: CH2MHILL (Lockwood Greene)
Architect: CH2MHILL (Lockwood Greene)
Contractor: FTR International
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2007-2008 Honorable Mention Award
Penske Truck Leasing Facility
Leighton Consulting, Inc.
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Leighton Consulting, Inc. (Leighton) was the geotechnical engineer of record during reclamation of a 40-acre gravel pit between Peoria and Pendleton Streets, east of Glenoaks Boulevard, in northeastern Sun Valley, City and County of Los Angeles. This project is for the 5-acre Lot 4 reclamation as a subset of these 40-acres, which has since been successfully redeveloped as a Penske Truck Leasing Facility which opened on December 31, 2007. All geotechnical work on Lot 4 for this Penske facility was by Leighton since 2004.
Prior to 2003, this pit was backfilled with up to 90 feet of hydraulically sluiced silts and clays, which were waste by-product from sand and gravel production at and near this site. Unlike the native dense and coarse alluvium in this area, these backfill materials consisted primarily of silts with some clays placed hydraulically at very low-densities. Therefore, these materials were very compressible; they were in a condition commonly encountered during off-shore land reclamation projects such as at artificial piers. At the beginning of 2004, this pit was predominantly backfilled with these silts and clays, but still at a lower grade than the surrounding industrial and residential neighborhoods. Leighton's services included (1) a Phase I Preliminary Environmental Site Assessment for refinancing of this project, (2) geotechnical exploration and design of the Lot 4 reclamation, (3) a methane survey for design of a methane mitigation system in accordance with City of Los Angeles requirements, and (3) geotechnical and construction materials testing during remedial earthwork, pile driving and construction of the truck leasing and maintenance facility. All of these tasks required City of Los Angeles Department of Building and Safety approval.
In 2004, this pit was backfilled up to adjacent grade and graded for drainage. Earthwork was observed and tested by Leighton. For support of asphalt pavements at grade, the upper 10-feet or more was backfilled with properly compacted fill reinforced with geogrids to reduce differential settlement and to provide more even support for new asphalt pavements, particularly for the pavements designed to support tractors and semi-trailers. Due to the potential for excessive total and differential settlement and consolidation of the 60‑plus-feet of unconsolidated sluiced silts and clays, the Penske truck leasing and maintenance facility, including a diesel fuel tank and fueling island, was supported on driven piles deriving support solely from the underlying native soils below the bottom of the filled in gravel pit. Hinged concrete approach slabs-in-grade were also constructed to accommodate differential settlement of the surrounding asphalt relative to the pile supported file' island and pile support structural concrete slab. Also, flexible couplings in utility "galleries" were used to accommodate differential settlement between the pile supported structure, newly placed fill over compressible sluiced fill, and undisturbed dense native soils at the northwestern perimeter of this lot.
To assist in refining casting lengths of driven pre-cast, pre-stressed concrete piles, Cone Penetrometer Test (CPT) soundings were used in conjunction with a Global Positioning System (GPS) unit, to verify depth to dense native alluvium under the proposed building and fuel island footprints with increased accuracy.
The City requirement of methane surveys and methane mitigation was implemented for this building. Methane was being produced by organic earth materials in the sluiced fill, and possibly other adjacent nearby sources. This facility was occupied at the end of December 2007.
Density testing was performed using a combination of nuclear density gauges and sand cones, in accordance with City of Los Angeles Department of Building and Safety requirements. Leighton has extensive experience with the City of Los Angeles Department of Building and Safety; and was therefore able to expedite Building and Safety approval of geotechnical and materials resting aspects of this project. The design and construction management team consisted primarily of The Facility DesignGroup headquartered in Smyrna, Georgia. This project resulted in a successful reclamation of an abandoned gravel pit for productive land use. Leighton Consulting, Inc. were able to reduce geotechnical mitigation costs, yet provide a safe and durable facility with respect to geotechnical and geoenvironmenral issues.
Owner: Penske Facility Design Group
Geotechnical Engineer: Leighton Consulting, Inc.
Civil Engineer: Civiltec Engineering Inc.
Structural Engineer: Anthony D. Ooten, Penske Facility Design Group
Architect: Richard Valente, Penske Facility Design Group
Contractor: Pena Grading and Demolition
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