GEOTECHNICAL ENGINEERING GROUP
CITY OF LOS ANGELES DEPARTMENT OF PUBLIC WORKS BUREAU OF ENGINEERING
GEOTECHNICAL ENGINEERING GROUP
GEOTECHNICAL DATA REPORT SECONDARY SEWER RENEWAL PROJECT (SSRP) SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. # SZC12312 GEO FILE # 11-092 DECEMBER 15, 2011
SSRP P21C WO SZC12312
DECEMBER 15, 2011 GEO FILE 11-092 TABLE OF CONTENTS
1.0 INTRODUCTION ............................................................................................................... 1 2.0 AREA DESCRIPTION....................................................................................................... 1 3.0 PROJECT SCOPE ............................................................................................................ 1 4.0 GEOLOGIC CONDITIONS............................................................................................... 2 4.1 Regional Geology .......................................................................................................... 2 4.2 Stratigraphy .................................................................................................................... 2 4.2.1 Alluvium (Qg, Qa, Qae) ......................................................................................... 3 4.2.2 Monterey Formation (Tm) ..................................................................................... 3 4.2.3 Middle Topanga Formation and Volcanic Rocks (Tts, Tvb) ............................ 3 4.2.4 Granitic Rocks - Basement Rock (grd, qd) ........................................................ 3 4.3 Groundwater................................................................................................................... 3 5.0 CLOSURE........................................................................................................................... 4
FIGURES Figure 1 – Vicinity Map Figure 2 – Soil Boring Locations Figure 3 – Geology Map Figure 4 – Seismic Hazard Zones Figure 5 – Historic Ground Water REFERENCES APPENDIX A: 1. Boring No. B-6C from Kleinfelder, Los Angeles Zoo project, Project No. 589588-02, dated May 11, 2001. (GEO File 01-260) 2. Boring No. 1 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-4103, dated March 16, 1993. (GEO File 92-947) 3. Borings No. B-1 to B-4 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-4529, dated January 30, February 2, & February 27, 1996. (GEO File 96-001) 4. Borings No. 3 to 6 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-3073, dated January 7 & 15, 1986. (GEO File S-1348)
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1.0 INTRODUCTION This report presents the results of a geotechnical evaluation conducted for the proposed Secondary Sewer Renewal Project (SSRP) P21C. A vicinity map of the project area is shown on Figure 1. This evaluation was conducted to provide typical geotechnical parameters for the project area based solely on document review and visual observation of the site area. No subsurface exploration or laboratory testing has been performed. The geotechnical parameters presented herein are expected to be representative of the general site area. However, subsurface variations exist and will most likely be encountered during construction of some of the proposed projects. When varying subsurface conditions are encountered, GEO shall be notified to evaluate the exposed conditions and provide supplemental recommendations as appropriate. The Geotechnical Engineering Group (GEO) prepared this report in response to the Wastewater Conveyance Engineering Division (WCED) request dated November 8, 2011. GEO’s research consisted of reconnaissance of the project area, identifying potential environmental hazards and gathering existing soil data in the vicinity of the sewer reaches through Navigate LA. The results of subsurface data used for this report can be found in Appendix A. The locations of borings reviewed for this study are shown on Figure 2 (Soil Boring Locations). 2.0 AREA DESCRIPTION The SSRP P21C Los Feliz Boulevard & 5 Freeway projects will renew secondary sewers in the area generally bounded by Griffith Park Drive to the north, Vista Del Valle Drive to the west, 5 Freeway to the east and Los Feliz Boulevard to the south. Most of the sewer reaches covered by this report are in gently sloping to steep sloping areas and surrounded by residential areas of the Los Feliz area. Some of the sites (4) are located in Griffith Park along Camp Road and Griffith Park Drive. 3.0 PROJECT SCOPE Our understanding of the project is based on the information presented in the “PreDesign Report, Collection System Settlement Agreement (CSSA) Program, Secondary Sewer Renewal Program (SSRP) P21C Los Feliz Boulevard & 5 Freeway” prepared by the Wastewater Conveyance Engineering Division dated October 2011. A total of 5,980 reach-feet (1.13 miles) of sewer pipe are recommended for renewal under this project. Actual Contractor's footage may be different. The scope consists of removing and replacing (R&R), spot repairs and/or lining of 8inch pipes; installing 7 maintenance holes; upgrading 1 drop connection; and removing 1 flush tank mechanism and remodel MH base.
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Invert depths for the reaches generally vary from approximately 5.5 feet to 14 feet with a maximum depth of 15.0 feet for a reach at the intersection of Amesbury Road and Cromwell Avenue.
4.0 GEOLOGIC CONDITIONS 4.1 Regional Geology The subject sites are located within the Transverse Ranges Geomorphic Province of southern California. The Transverse Ranges are characterized by roughly east-west trending, convergent deformational structural features (linear topography, folding, and faulting) in contrast to the predominant northwest-southeast structural trend found in the other geomorphic provinces in California. The sites are situated on the southern flank of the Santa Monica Mountains, which separates the San Fernando Valley on the north from Los Angeles Basin to the south. The Santa Monica Mountains are an east-west trending mountain range composed to folded and faulted sedimentary, metamorphic, and igneous rock, which compromises the southern boundary of the Transverse Range. Regional mapping by Dibblee indicates that, in general, the sedimentary bedrock in the Los Feliz area has a northwest to northeast strike and dips between 10 and 30 degrees to the northeast to northwest. In general the sedimentary bedrock within the project area of Griffith Park east west and dips between 30 and 80 degrees to the north. The bedrock most likely to be encountered in the sites near Los Feliz are sedimentary and granodiorite. The bedrock most likely to be encountered in Griffith Park are sedimentary and basaltic volcanic. Topography in the vicinity of the sites near Los Feliz is typified by gently to steeply sloping surfaces with the slope direction generally to the east or south. Within Griffith Park is typified by moderate to steeply sloping surfaces with the slope direction generally to the east or north. The elevation at the sites near Los Feliz varies from approximately 500 to 1,000 feet above mean sea level (msl). The elevation at the sites located within Griffith Park varies from approximately 1,000 to 1,300 feet above mean sea level (msl). Figure 3 is a copy of the Geologic Map for this project site. As shown on the Seismic Hazard Zones, Figure 4, most of the sites lie within Landslide Seismic Hazard Zones (CDMG, 1999). 4.2 Stratigraphy No subsurface exploration was conducted for this project, all stratigraphic descriptions and relationships are inferred from California DWR, 1961 and Dibblee, T.W., Jr., 1991, Geologic Map of the Beverly Hills and Van Nuys (South ½) Quadrangles, Los Angeles County, California, Dibblee Geological Foundation Map DF-31, scale 1:24,000.
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4.2.1 Alluvium (Qg, Qa, Qae) Within the project area the alluvium consists primarily of clays, silts and sands with gravel, cobbles and boulders. Qg is alluvium consisting of sand and gravel with cobbles and boulders of major stream and river deposits. Qa is alluvium consisting of sand, clays and gravels which include sands and gravels with some cobbles and boulders of minor stream channels. Qae is similar to Qa but older. 4.2.2 Monterey Formation (Tm) Within the project area, around the Los Feliz area the Tm Formation of Upper Miocene age sedimentary bedrock is composed of white weathering, thin bedded, platy, siliceous shale, hard to semi-chalky. Bedrock of the Monterey Formation has surface exposes in the area and can be expected to be encountered in some areas just below the ground surface. 4.2.3 Middle Topanga Formation and Volcanic Rocks (Tts, Tvb) Within the project area the Middle Topanga Formation of Miocene age sedimentary bedrock are composed of light gray to tan moderately hard sandstone (Tts). In addition, hard basaltic igneous volcanic rocks (Tvb) that are dark gray to black, fine grained, massive to vesicular and/or pillowed exist with the project area. Bedrock of the Middle Topanga Formation has surface exposes in the area and can be expected to be encountered in some areas just below the ground surface. 4.2.4 Granitic Rocks - Basement Rock (grd, qd) Within the project area, this unit is crystalline basement rock of the Mesozoic Era and are composed of granodiorite (grd) and medium to light gray quartz diorite (qd) granitic igneous rock. The granodiorite rock is massive, moderately hard and consists of mostly feldspar with minor amounts of quartz and biotite. The quartz diorite massive to vaguely gneissoid, moderately hard to somewhat incoherent where weathered. 4.3 Groundwater Groundwater and seepage were encountered in 4 of the previous borings at depths of 19, 26 & 33 feet below ground surface. The California Division of Mines and Geology, Historic Ground Water (CDMG, 1998), presents historic groundwater data for the site area, as shown in attached Figure No.5 – Historic Ground Water. Seasonal fluctuations in groundwater levels may occur due to variations in climate, irrigation, and other factors not readily evident.
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Project Sites
Legend af - artificial fill Qg - stream and river channel deposits of boulders, cobbles, gravel, sand and silt Qa - Alluvium: unconsolidated, floodplain deposits of silt, sand, gravel, cobbles and boulders includes gravel and sand from stream deposits Qoa - Older alluvium, gray to light brown, silt-clay, sand, pebble-gravel, cobbles and boulders similar similar to Qa. Tm - White weathering, thin bedded, platy, siliceous shale, hard to semi-chalky Ttusc - light gray massive sandstone with pebble-cobble conglomerate Ttucg - light to medium gray coase pebbly sandstone to cobble-boulder conglomerate Tts - light gray to tan moderately hard sandstone Tvb - dark gray to black basaltic rocks grd - granodiorite, light gray, massive moderately hard Dibblee, Thomas, 1991, Geologic Map of the Hollywood and Burbank (South 1/2) Quadrangles, Los Angeles County, California: Dibblee Geological Foundation Map #DF-30.
Geology Map SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
N not to scale
FIGURE 3
Project Sites
Reference: "Official Map of Seismic Hazard Zones, Hollywood", March 25, 1999, California Department of Conservation, Division of Mines and Geology.
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SEISMIC HAZARD ZONES SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
FIGURE 4
Project Site
Historically Highest Ground Water Contours and Borehole Data Location, Hollywood Quadrangle Department of Conservation, Division of Mines and Geology.
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Historic Ground Water SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
FIGURE 5
APPENDIX A
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3.0 GEOTECHNICAL DATA REPORT The recommendations given in this design memorandum are based on geotechnical data contained in the project GDR. The GDR summarizes geotechnical data and test results for the proposed Secondary Sewer Renewal Project (SSRP) P21C. 4.0 RECOMMENDATIONS 4.1 Contaminated Soil Soils which have visible staining or an odor should be segregated and stockpiled. The Geotechnical Engineering Group (GEO) should be immediately notified at 213-8470525. The stockpiles should be barricaded near the excavation area, away from drainage areas or catch basins, on an impermeable plastic liner (6 mil nominal thickness and tested at 100 psi strength). Caution must be taken to separate any contaminated soil from the remainder of the excavated material. If only a small amount of contaminated soil is encountered, it may be drummed in 55-gallon steel drums with sealing lids. The soil will then be sampled in a random and representative manner under the direction of GEO. Samples will be tested by a State-certified environmental laboratory. Following receipt of the analytical results the soil will be classified as hazardous or non hazardous. Any contaminated material (soil, asphalt, railroad ballast, concrete, or debris) that is to be hauled off the site is considered a "waste product" and must be classified as hazardous or non hazardous waste under all criteria by both State and Federal Codes prior to disposal. If the waste soil or other material is determined hazardous, a hazardous waste manifest will be prepared by the Contractor or its qualified representative and the material transported to an appropriate class of facility for recycling or landfill disposal by a registered hazardous material transporter. If the soil is non hazardous but still exceeds levels that can be returned to the excavation, a less costly non hazardous transporter and soil recycling facility may be used if no hazardous constituents are present above their respective action levels. The Bureau of Contract Administration Inspector for the project shall be notified of all contaminated material removals, and will document all quantities, help insure soil segregation and ensure copies of signed manifests are retained for the City records. 4.2 Groundwater According to the previous borings near the sites, groundwater generally may not be encountered in the project areas, however, groundwater can be expected to be encountered in areas within fill soils, alluvium and near contacts with the bedrock.
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4.3 Temporary Excavations No soils boring information was found in the project areas. Field reconnaissance within the areas for information of the bedrock was completed. Based on our understanding of the typical subsurface conditions in the site area, most of the materials within the project area should be readily excavated by conventional earthmoving equipment in good operating condition; however, most excavations within the bedrock will require the use of jackhammers for stronger portions of the bedrock formations. All temporary excavations shall conform to the State of California Construction Safety Orders (CAL/OSHA). Unsurcharged, temporary vertical excavations to a maximum depth of 5 feet are generally expected to be suitable for most of the proposed projects. Unsurcharged deeper excavations to a maximum of 10 feet shall be sloped at a 1:1 (H:V) or flatter inclination from the existing ground surface to the bottom of the excavation or should be shored. Temporary sloped excavations greater than 10 feet are not anticipated for the projects. Any excavation that enters the influence zone, 1:1 (H:V) projection downward, of an adjacent structure or utility shall utilize shoring. 4.4 Temporary Shoring All shoring shall be in accordance with Section 306-1.1.6 of the Standard Specifications for Public Works Construction, latest edition (SSPWC), Title 8, Division 1, Chapter 4, Subchapter 4 of the California code of Regulations: CAL/OSHA Construction Safety Orders. Type B soil shall be used for clayey material and bedrock and Type C soil for sandy and gravelly material. Soldier piles or sheet piles may be used to support vertical cuts. Cantilevered shoring shall be designed to withstand an active equivalent fluid pressure (EFP) of 35 pcf. Braced shoring is recommended in areas where shoring will be located close to existing utilities to limit shoring deflections. Braced shoring can be designed using a uniform rectangular pressure of 26H pounds per square foot, where H is equal to the depth of the excavation in feet being shored. This design assumes a level backslope and that no hydrostatic pressure is allowed to develop behind the shoring. Cantilevered shoring is not recommended for support of structures or utilities that cannot tolerate ½ inch or more lateral or vertical movement In addition to the above lateral pressure from retained earth, lateral pressures from other superimposed loads, such as those from vehicle traffic and adjacent structures, shall be added to the above recommended lateral earth pressures, if the loads fall within a 1:1 projection of the shoring. A surcharge load equivalent to an additional 100 pound per square foot of retained soil shall be applied to the upper 10 feet of shoring if light vehicular traffic is expected within 0.7H. If heavier traffic loads are anticipated near the top of the shoring, additional analysis will be required. Heavy construction equipment, its wheels or outrigger loads that are located within a distance equal to 0.7H feet of the face of the shoring will be considered as surcharge loads in shoring calculations. The shoring design must consider support of the proposed adjacent pavements,
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structures, and/or underground utilities. Also, the effects of shoring deflection on supported pipelines and structures shall be considered. Solid sheeting shall be used in granular soils. Any and all voids that may develop behind the shoring system shall be immediately grouted. Resistance of shoring to lateral loads will be provided by passive earth pressure. An allowable passive bearing against the onsite dense alluvial soils may be taken as an equivalent fluid of 250 pcf to a maximum of 2,500 psf. Passive resistance may be considered as starting at 1-foot below the bottom of excavation. Passive pressures presented in this report are based on the assumption that slurry or concrete will be used to backfill the soldier piles. GEO shall review the plans and specifications for proposed shoring and a City Inspector shall observe the installation of shoring. Excavation shall proceed in such a manner that no voids are developed between the shoring and supported soil. Any voids between the shoring and supported soils shall be immediately filled with compacted sand or slurry. All shoring shall conform to Section 306-1.1 of the Standard Specifications for Public Works Construction, 2009 Edition. Shoring shall fully support the soil around the existing utilities. At no time shall sheeting/ lagging be connected to any existing utilities. No trench box system or shield will be allowed. Per the “Characterization of Ground Behavior According to Soil Type” (Deere, et. al. 1969), ground behavior characterization for shoring design shall generally assume “firm to rapidly raveling” condition for excavation in clayey material and bedrock and “rapid raveling to running” condition for excavation in sandy and gravelly material. 4.5 Pipe Bedding Pipe bedding material and placement shall conform to Section 306-1.2.1 of the SSPWC except as modified herein. Limited jetting and vibration of the pipe bedding may be allowed for a maximum vertical distance of 1 foot above the crown of pipe. This procedure is allowed for areas of the pipe bedding that are inaccessible to mechanical compaction, such as the haunches of the pipe. Caution must follow Section 306-1.3.3 of the SSPWC (including modifications as per Brown Book) for the limited jetting. All loose, disturbed, or otherwise unsuitable material at the bottom of trench shall be removed prior to placement of bedding material. Bedding will be placed on firm soil to prevent potential settlement of the sewer pipe. Excavated material may be placed and mechanically compacted up to the proposed bottom of the trench. All requirements listed in the Backfill Section of this report apply. At the contractor’s expense, the contractor may use CLSM as recommended in the Backfill Section of this report. 4.6 Backfill Trench excavations for utility pipes generally may be backfilled with onsite soils under the observation of a City Inspector. However, the highly plastic clay is not easy to
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compact and may be replaced with suitable import material. After utility pipes have been laid and properly bedded, the space around the pipe should be backfilled with clean sand (having sand equivalent of 30 or greater) or gravel to a depth of approximately 1 foot over the top of the pipe, before the controlled backfill is placed. If import materials are required for backfill, they shall be predominantly granular in nature with at least 80% passing the u.s. standard #4 sieve and no more than 35% mostly non-plastic material passing the No. 200 sieve. Import material will have low expansive potential (EI less than 50) and will be uncontaminated and free of organic or inorganic debris and materials larger than 3 inches. Import material will be tested and approved by the Project Engineer prior to importing to the job site. All soil used for backfill will be cleaned of organics, hazardous materials, and all debris larger than 3 inches prior to placement as backfill. Existing fine grained silt and clay soils within the project area are typically expected to be several percentage points above the optimum moisture content. The contractor shall assume that these materials will need to be dried or mixed with dryer materials in order to make them suitable for compaction. Alternatively, the contractor may use 1 sack of cement per cubic yard of Concrete Low Strength Material (CLSM) per the SSPWC. All backfill will be placed in conformance with Section 306-1.3 of the SSPWC, latest edition, and Brown Book modifications. Flooding of any type is not allowed under any circumstance. 4.7 Maintenance Holes and Drop Connections A bearing capacity of 2,500 psf may be used for the design of the proposed maintenance holes and drop connections. No increases in bearing capacity are allowed for increased depths or widths. Any disturbed material and materials too soft to support the structure will be removed and replaced with properly compacted material. Total structure settlement constructed in accordance with the recommendations presented herein is not expected to exceed ½ - inch. 4.8 Review of Plans and Specifications It is recommended that GEO review preliminary plans to provide timely geotechnical comments for design consideration. GEO shall review the plans and specifications as part of the final plan check stage. 4.9 Further Geotechnical Study No further geotechnical study is recommended for the secondary sewer renewal project within P21C. As previously stated, subsurface conditions dissimilar to those described herein most likely exist and may be encountered during construction of some of the propose projects. When varying subsurface conditions are encountered, GEO shall be notified to evaluate the exposed conditions and provide supplemental recommendations
REFERENCES 1. Standard Specifications for Public Works Construction “Greenbook”, 2009 edition. 2. “Brown Book”, City of Los Angeles Department of Public Works, Additions and Amendments to the 2009 Edition of the Standard Specifications for Public Works Construction. 3. Dibblee, T.W., Jr., 1991, Geologic Map of the Los Angeles Quadrangles, Los Angeles County, California, Dibblee Geological Foundation Map DF-31, scale 1:24,000. 4. Deere, Peck, Monsees and Schmidt, 1969, “Characterization of Ground Behavior According to Type.”
GEOTECHNICAL ENGINEERING GROUP
GEOTECHNICAL DATA REPORT SECONDARY SEWER RENEWAL PROJECT (SSRP) SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. # SZC12312 GEO FILE # 11-092 DECEMBER 15, 2011
SSRP P21C WO SZC12312
DECEMBER 15, 2011 GEO FILE 11-092 TABLE OF CONTENTS
1.0 INTRODUCTION ............................................................................................................... 1 2.0 AREA DESCRIPTION....................................................................................................... 1 3.0 PROJECT SCOPE ............................................................................................................ 1 4.0 GEOLOGIC CONDITIONS............................................................................................... 2 4.1 Regional Geology .......................................................................................................... 2 4.2 Stratigraphy .................................................................................................................... 2 4.2.1 Alluvium (Qg, Qa, Qae) ......................................................................................... 3 4.2.2 Monterey Formation (Tm) ..................................................................................... 3 4.2.3 Middle Topanga Formation and Volcanic Rocks (Tts, Tvb) ............................ 3 4.2.4 Granitic Rocks - Basement Rock (grd, qd) ........................................................ 3 4.3 Groundwater................................................................................................................... 3 5.0 CLOSURE........................................................................................................................... 4
FIGURES Figure 1 – Vicinity Map Figure 2 – Soil Boring Locations Figure 3 – Geology Map Figure 4 – Seismic Hazard Zones Figure 5 – Historic Ground Water REFERENCES APPENDIX A: 1. Boring No. B-6C from Kleinfelder, Los Angeles Zoo project, Project No. 589588-02, dated May 11, 2001. (GEO File 01-260) 2. Boring No. 1 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-4103, dated March 16, 1993. (GEO File 92-947) 3. Borings No. B-1 to B-4 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-4529, dated January 30, February 2, & February 27, 1996. (GEO File 96-001) 4. Borings No. 3 to 6 from Department of General Services Standards Division, Report of Subsurface Investigation, Lab No. 140-3073, dated January 7 & 15, 1986. (GEO File S-1348)
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1.0 INTRODUCTION This report presents the results of a geotechnical evaluation conducted for the proposed Secondary Sewer Renewal Project (SSRP) P21C. A vicinity map of the project area is shown on Figure 1. This evaluation was conducted to provide typical geotechnical parameters for the project area based solely on document review and visual observation of the site area. No subsurface exploration or laboratory testing has been performed. The geotechnical parameters presented herein are expected to be representative of the general site area. However, subsurface variations exist and will most likely be encountered during construction of some of the proposed projects. When varying subsurface conditions are encountered, GEO shall be notified to evaluate the exposed conditions and provide supplemental recommendations as appropriate. The Geotechnical Engineering Group (GEO) prepared this report in response to the Wastewater Conveyance Engineering Division (WCED) request dated November 8, 2011. GEO’s research consisted of reconnaissance of the project area, identifying potential environmental hazards and gathering existing soil data in the vicinity of the sewer reaches through Navigate LA. The results of subsurface data used for this report can be found in Appendix A. The locations of borings reviewed for this study are shown on Figure 2 (Soil Boring Locations). 2.0 AREA DESCRIPTION The SSRP P21C Los Feliz Boulevard & 5 Freeway projects will renew secondary sewers in the area generally bounded by Griffith Park Drive to the north, Vista Del Valle Drive to the west, 5 Freeway to the east and Los Feliz Boulevard to the south. Most of the sewer reaches covered by this report are in gently sloping to steep sloping areas and surrounded by residential areas of the Los Feliz area. Some of the sites (4) are located in Griffith Park along Camp Road and Griffith Park Drive. 3.0 PROJECT SCOPE Our understanding of the project is based on the information presented in the “PreDesign Report, Collection System Settlement Agreement (CSSA) Program, Secondary Sewer Renewal Program (SSRP) P21C Los Feliz Boulevard & 5 Freeway” prepared by the Wastewater Conveyance Engineering Division dated October 2011. A total of 5,980 reach-feet (1.13 miles) of sewer pipe are recommended for renewal under this project. Actual Contractor's footage may be different. The scope consists of removing and replacing (R&R), spot repairs and/or lining of 8inch pipes; installing 7 maintenance holes; upgrading 1 drop connection; and removing 1 flush tank mechanism and remodel MH base.
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Invert depths for the reaches generally vary from approximately 5.5 feet to 14 feet with a maximum depth of 15.0 feet for a reach at the intersection of Amesbury Road and Cromwell Avenue.
4.0 GEOLOGIC CONDITIONS 4.1 Regional Geology The subject sites are located within the Transverse Ranges Geomorphic Province of southern California. The Transverse Ranges are characterized by roughly east-west trending, convergent deformational structural features (linear topography, folding, and faulting) in contrast to the predominant northwest-southeast structural trend found in the other geomorphic provinces in California. The sites are situated on the southern flank of the Santa Monica Mountains, which separates the San Fernando Valley on the north from Los Angeles Basin to the south. The Santa Monica Mountains are an east-west trending mountain range composed to folded and faulted sedimentary, metamorphic, and igneous rock, which compromises the southern boundary of the Transverse Range. Regional mapping by Dibblee indicates that, in general, the sedimentary bedrock in the Los Feliz area has a northwest to northeast strike and dips between 10 and 30 degrees to the northeast to northwest. In general the sedimentary bedrock within the project area of Griffith Park east west and dips between 30 and 80 degrees to the north. The bedrock most likely to be encountered in the sites near Los Feliz are sedimentary and granodiorite. The bedrock most likely to be encountered in Griffith Park are sedimentary and basaltic volcanic. Topography in the vicinity of the sites near Los Feliz is typified by gently to steeply sloping surfaces with the slope direction generally to the east or south. Within Griffith Park is typified by moderate to steeply sloping surfaces with the slope direction generally to the east or north. The elevation at the sites near Los Feliz varies from approximately 500 to 1,000 feet above mean sea level (msl). The elevation at the sites located within Griffith Park varies from approximately 1,000 to 1,300 feet above mean sea level (msl). Figure 3 is a copy of the Geologic Map for this project site. As shown on the Seismic Hazard Zones, Figure 4, most of the sites lie within Landslide Seismic Hazard Zones (CDMG, 1999). 4.2 Stratigraphy No subsurface exploration was conducted for this project, all stratigraphic descriptions and relationships are inferred from California DWR, 1961 and Dibblee, T.W., Jr., 1991, Geologic Map of the Beverly Hills and Van Nuys (South ½) Quadrangles, Los Angeles County, California, Dibblee Geological Foundation Map DF-31, scale 1:24,000.
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4.2.1 Alluvium (Qg, Qa, Qae) Within the project area the alluvium consists primarily of clays, silts and sands with gravel, cobbles and boulders. Qg is alluvium consisting of sand and gravel with cobbles and boulders of major stream and river deposits. Qa is alluvium consisting of sand, clays and gravels which include sands and gravels with some cobbles and boulders of minor stream channels. Qae is similar to Qa but older. 4.2.2 Monterey Formation (Tm) Within the project area, around the Los Feliz area the Tm Formation of Upper Miocene age sedimentary bedrock is composed of white weathering, thin bedded, platy, siliceous shale, hard to semi-chalky. Bedrock of the Monterey Formation has surface exposes in the area and can be expected to be encountered in some areas just below the ground surface. 4.2.3 Middle Topanga Formation and Volcanic Rocks (Tts, Tvb) Within the project area the Middle Topanga Formation of Miocene age sedimentary bedrock are composed of light gray to tan moderately hard sandstone (Tts). In addition, hard basaltic igneous volcanic rocks (Tvb) that are dark gray to black, fine grained, massive to vesicular and/or pillowed exist with the project area. Bedrock of the Middle Topanga Formation has surface exposes in the area and can be expected to be encountered in some areas just below the ground surface. 4.2.4 Granitic Rocks - Basement Rock (grd, qd) Within the project area, this unit is crystalline basement rock of the Mesozoic Era and are composed of granodiorite (grd) and medium to light gray quartz diorite (qd) granitic igneous rock. The granodiorite rock is massive, moderately hard and consists of mostly feldspar with minor amounts of quartz and biotite. The quartz diorite massive to vaguely gneissoid, moderately hard to somewhat incoherent where weathered. 4.3 Groundwater Groundwater and seepage were encountered in 4 of the previous borings at depths of 19, 26 & 33 feet below ground surface. The California Division of Mines and Geology, Historic Ground Water (CDMG, 1998), presents historic groundwater data for the site area, as shown in attached Figure No.5 – Historic Ground Water. Seasonal fluctuations in groundwater levels may occur due to variations in climate, irrigation, and other factors not readily evident.
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Project Sites
Legend af - artificial fill Qg - stream and river channel deposits of boulders, cobbles, gravel, sand and silt Qa - Alluvium: unconsolidated, floodplain deposits of silt, sand, gravel, cobbles and boulders includes gravel and sand from stream deposits Qoa - Older alluvium, gray to light brown, silt-clay, sand, pebble-gravel, cobbles and boulders similar similar to Qa. Tm - White weathering, thin bedded, platy, siliceous shale, hard to semi-chalky Ttusc - light gray massive sandstone with pebble-cobble conglomerate Ttucg - light to medium gray coase pebbly sandstone to cobble-boulder conglomerate Tts - light gray to tan moderately hard sandstone Tvb - dark gray to black basaltic rocks grd - granodiorite, light gray, massive moderately hard Dibblee, Thomas, 1991, Geologic Map of the Hollywood and Burbank (South 1/2) Quadrangles, Los Angeles County, California: Dibblee Geological Foundation Map #DF-30.
Geology Map SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
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FIGURE 3
Project Sites
Reference: "Official Map of Seismic Hazard Zones, Hollywood", March 25, 1999, California Department of Conservation, Division of Mines and Geology.
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SEISMIC HAZARD ZONES SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
FIGURE 4
Project Site
Historically Highest Ground Water Contours and Borehole Data Location, Hollywood Quadrangle Department of Conservation, Division of Mines and Geology.
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Historic Ground Water SSRP P21C LOS FELIZ BOULEVARD AND 5 FREEWAY W.O. SZC 12312 LOS ANGELES, CALIFORNIA
BUREAU OF ENGINEERING GEOTECHNICAL ENGINEERING GROUP (GEO) FILE No.: 11-092 DATE: DECEMBER, 2011
FIGURE 5
APPENDIX A
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3.0 GEOTECHNICAL DATA REPORT The recommendations given in this design memorandum are based on geotechnical data contained in the project GDR. The GDR summarizes geotechnical data and test results for the proposed Secondary Sewer Renewal Project (SSRP) P21C. 4.0 RECOMMENDATIONS 4.1 Contaminated Soil Soils which have visible staining or an odor should be segregated and stockpiled. The Geotechnical Engineering Group (GEO) should be immediately notified at 213-8470525. The stockpiles should be barricaded near the excavation area, away from drainage areas or catch basins, on an impermeable plastic liner (6 mil nominal thickness and tested at 100 psi strength). Caution must be taken to separate any contaminated soil from the remainder of the excavated material. If only a small amount of contaminated soil is encountered, it may be drummed in 55-gallon steel drums with sealing lids. The soil will then be sampled in a random and representative manner under the direction of GEO. Samples will be tested by a State-certified environmental laboratory. Following receipt of the analytical results the soil will be classified as hazardous or non hazardous. Any contaminated material (soil, asphalt, railroad ballast, concrete, or debris) that is to be hauled off the site is considered a "waste product" and must be classified as hazardous or non hazardous waste under all criteria by both State and Federal Codes prior to disposal. If the waste soil or other material is determined hazardous, a hazardous waste manifest will be prepared by the Contractor or its qualified representative and the material transported to an appropriate class of facility for recycling or landfill disposal by a registered hazardous material transporter. If the soil is non hazardous but still exceeds levels that can be returned to the excavation, a less costly non hazardous transporter and soil recycling facility may be used if no hazardous constituents are present above their respective action levels. The Bureau of Contract Administration Inspector for the project shall be notified of all contaminated material removals, and will document all quantities, help insure soil segregation and ensure copies of signed manifests are retained for the City records. 4.2 Groundwater According to the previous borings near the sites, groundwater generally may not be encountered in the project areas, however, groundwater can be expected to be encountered in areas within fill soils, alluvium and near contacts with the bedrock.
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4.3 Temporary Excavations No soils boring information was found in the project areas. Field reconnaissance within the areas for information of the bedrock was completed. Based on our understanding of the typical subsurface conditions in the site area, most of the materials within the project area should be readily excavated by conventional earthmoving equipment in good operating condition; however, most excavations within the bedrock will require the use of jackhammers for stronger portions of the bedrock formations. All temporary excavations shall conform to the State of California Construction Safety Orders (CAL/OSHA). Unsurcharged, temporary vertical excavations to a maximum depth of 5 feet are generally expected to be suitable for most of the proposed projects. Unsurcharged deeper excavations to a maximum of 10 feet shall be sloped at a 1:1 (H:V) or flatter inclination from the existing ground surface to the bottom of the excavation or should be shored. Temporary sloped excavations greater than 10 feet are not anticipated for the projects. Any excavation that enters the influence zone, 1:1 (H:V) projection downward, of an adjacent structure or utility shall utilize shoring. 4.4 Temporary Shoring All shoring shall be in accordance with Section 306-1.1.6 of the Standard Specifications for Public Works Construction, latest edition (SSPWC), Title 8, Division 1, Chapter 4, Subchapter 4 of the California code of Regulations: CAL/OSHA Construction Safety Orders. Type B soil shall be used for clayey material and bedrock and Type C soil for sandy and gravelly material. Soldier piles or sheet piles may be used to support vertical cuts. Cantilevered shoring shall be designed to withstand an active equivalent fluid pressure (EFP) of 35 pcf. Braced shoring is recommended in areas where shoring will be located close to existing utilities to limit shoring deflections. Braced shoring can be designed using a uniform rectangular pressure of 26H pounds per square foot, where H is equal to the depth of the excavation in feet being shored. This design assumes a level backslope and that no hydrostatic pressure is allowed to develop behind the shoring. Cantilevered shoring is not recommended for support of structures or utilities that cannot tolerate ½ inch or more lateral or vertical movement In addition to the above lateral pressure from retained earth, lateral pressures from other superimposed loads, such as those from vehicle traffic and adjacent structures, shall be added to the above recommended lateral earth pressures, if the loads fall within a 1:1 projection of the shoring. A surcharge load equivalent to an additional 100 pound per square foot of retained soil shall be applied to the upper 10 feet of shoring if light vehicular traffic is expected within 0.7H. If heavier traffic loads are anticipated near the top of the shoring, additional analysis will be required. Heavy construction equipment, its wheels or outrigger loads that are located within a distance equal to 0.7H feet of the face of the shoring will be considered as surcharge loads in shoring calculations. The shoring design must consider support of the proposed adjacent pavements,
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structures, and/or underground utilities. Also, the effects of shoring deflection on supported pipelines and structures shall be considered. Solid sheeting shall be used in granular soils. Any and all voids that may develop behind the shoring system shall be immediately grouted. Resistance of shoring to lateral loads will be provided by passive earth pressure. An allowable passive bearing against the onsite dense alluvial soils may be taken as an equivalent fluid of 250 pcf to a maximum of 2,500 psf. Passive resistance may be considered as starting at 1-foot below the bottom of excavation. Passive pressures presented in this report are based on the assumption that slurry or concrete will be used to backfill the soldier piles. GEO shall review the plans and specifications for proposed shoring and a City Inspector shall observe the installation of shoring. Excavation shall proceed in such a manner that no voids are developed between the shoring and supported soil. Any voids between the shoring and supported soils shall be immediately filled with compacted sand or slurry. All shoring shall conform to Section 306-1.1 of the Standard Specifications for Public Works Construction, 2009 Edition. Shoring shall fully support the soil around the existing utilities. At no time shall sheeting/ lagging be connected to any existing utilities. No trench box system or shield will be allowed. Per the “Characterization of Ground Behavior According to Soil Type” (Deere, et. al. 1969), ground behavior characterization for shoring design shall generally assume “firm to rapidly raveling” condition for excavation in clayey material and bedrock and “rapid raveling to running” condition for excavation in sandy and gravelly material. 4.5 Pipe Bedding Pipe bedding material and placement shall conform to Section 306-1.2.1 of the SSPWC except as modified herein. Limited jetting and vibration of the pipe bedding may be allowed for a maximum vertical distance of 1 foot above the crown of pipe. This procedure is allowed for areas of the pipe bedding that are inaccessible to mechanical compaction, such as the haunches of the pipe. Caution must follow Section 306-1.3.3 of the SSPWC (including modifications as per Brown Book) for the limited jetting. All loose, disturbed, or otherwise unsuitable material at the bottom of trench shall be removed prior to placement of bedding material. Bedding will be placed on firm soil to prevent potential settlement of the sewer pipe. Excavated material may be placed and mechanically compacted up to the proposed bottom of the trench. All requirements listed in the Backfill Section of this report apply. At the contractor’s expense, the contractor may use CLSM as recommended in the Backfill Section of this report. 4.6 Backfill Trench excavations for utility pipes generally may be backfilled with onsite soils under the observation of a City Inspector. However, the highly plastic clay is not easy to
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compact and may be replaced with suitable import material. After utility pipes have been laid and properly bedded, the space around the pipe should be backfilled with clean sand (having sand equivalent of 30 or greater) or gravel to a depth of approximately 1 foot over the top of the pipe, before the controlled backfill is placed. If import materials are required for backfill, they shall be predominantly granular in nature with at least 80% passing the u.s. standard #4 sieve and no more than 35% mostly non-plastic material passing the No. 200 sieve. Import material will have low expansive potential (EI less than 50) and will be uncontaminated and free of organic or inorganic debris and materials larger than 3 inches. Import material will be tested and approved by the Project Engineer prior to importing to the job site. All soil used for backfill will be cleaned of organics, hazardous materials, and all debris larger than 3 inches prior to placement as backfill. Existing fine grained silt and clay soils within the project area are typically expected to be several percentage points above the optimum moisture content. The contractor shall assume that these materials will need to be dried or mixed with dryer materials in order to make them suitable for compaction. Alternatively, the contractor may use 1 sack of cement per cubic yard of Concrete Low Strength Material (CLSM) per the SSPWC. All backfill will be placed in conformance with Section 306-1.3 of the SSPWC, latest edition, and Brown Book modifications. Flooding of any type is not allowed under any circumstance. 4.7 Maintenance Holes and Drop Connections A bearing capacity of 2,500 psf may be used for the design of the proposed maintenance holes and drop connections. No increases in bearing capacity are allowed for increased depths or widths. Any disturbed material and materials too soft to support the structure will be removed and replaced with properly compacted material. Total structure settlement constructed in accordance with the recommendations presented herein is not expected to exceed ½ - inch. 4.8 Review of Plans and Specifications It is recommended that GEO review preliminary plans to provide timely geotechnical comments for design consideration. GEO shall review the plans and specifications as part of the final plan check stage. 4.9 Further Geotechnical Study No further geotechnical study is recommended for the secondary sewer renewal project within P21C. As previously stated, subsurface conditions dissimilar to those described herein most likely exist and may be encountered during construction of some of the propose projects. When varying subsurface conditions are encountered, GEO shall be notified to evaluate the exposed conditions and provide supplemental recommendations
REFERENCES 1. Standard Specifications for Public Works Construction “Greenbook”, 2009 edition. 2. “Brown Book”, City of Los Angeles Department of Public Works, Additions and Amendments to the 2009 Edition of the Standard Specifications for Public Works Construction. 3. Dibblee, T.W., Jr., 1991, Geologic Map of the Los Angeles Quadrangles, Los Angeles County, California, Dibblee Geological Foundation Map DF-31, scale 1:24,000. 4. Deere, Peck, Monsees and Schmidt, 1969, “Characterization of Ground Behavior According to Type.”
