1970 s and. Site Location Map. and shed transform the. Gateway Project.

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2 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 2 of 10 Tulare Park Improvement Project Tulare Park is an existing 8,000 square foot park that is located within the Port s portion of the Blue-Greenway along Islais Creek shoreline, between Illinois and Third Streets. The park was originally constructed in the early 1970 s and is in need of major improvements. This project will include ADA upgrades to the park, new park furnishingss and signage; and new California native shorelinee landscaping. The ADAA upgrades will include an accessiblee path between Illinois and Third Streets. The path will include a small bridge structure extending over the Creek near Illinois Street. A five feet diameter sewer force main owned and operated by the San Francisco Public Utilities Commission (SFPUC) runs through the project area. The location of the site and vicinity is shown on Figure 1, Site Location Map. Bayview Gateway Project The Bayview Gateway Project will create a new one acre public open space along the southern bank of Islais Creek in San Francisco s south east waterfront. The Project Site is bound by Islais Creek on the north, Cargo Way on the South, 3 rd Street on the West, and Illinois Street on the East. This area was reclaimed in the 1900 s to create a working waterfront with timber wharf and shed buildings. The shed was removed in the early 1980 s leaving an asphalt covered lot. The Project will demolish the existing timber wharf, rehabilitate the seawall, and transform the asphalt lot into a public green space with walkways, plaza spaces and green spaces to provide water view and visual creek access. The location of the site and vicinity is shown on Figure 1, Site Location Map. Scope of Work The purpose of this geotechnical memorandum is to provide soil parameters for design of appropriate foundation system for the new pedestrian bridge walkway along the waterfront for Tulare Park Project and new pedestrian concrete viewing boardwalk for Bayview Gateway Project. Previous Field Investigations For preparation of this geotechnical memorandum, a geotechnical investigation report for the Illinois Street Bridge, prepared by Treadwelll & Rollo Environmental and Geotechnical Consultants, dated December 21, 2001 and geotechnical study report for the retrofit of Islais Creek Bridge, prepared by AGS, Inc., dated May 2008 were reviewed in order to develop an understanding of the expected subsurface conditions for the project. Subsurface Condition Tulare Park Improvement Project The subsurface profile primarily consists of fill, Bay Mud, interbedded sands and clays above Old Bay Clay. Boring B-1(Treadwell & Rollo), drilled at the north abutment of Illinois Street Bridge encountered about 23 feet of heterogeneous fill. The fill consists of densee clayey sand above the water table and loose sand and gravel below the water table. The fill is underlain by soft to medium stiff clay with organics, known locally as Bay Mud. The Bay Mud is about 98 feet thick and is weak and compressible. Alternating layers of sand and clay underlie the Bay Mud. The sand has various amounts of fines and is densee to very dense and the clay is very stiff to hard. This alternating layer of sand and clay is underlain by a layer of very stiff Old Bay Clay San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

3 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 3 of 10 to the maximum depth explored of feet. Boring B-17 (AGS, Inc.), was drilled approximately 47 feet north of the northern abutment of Third Street Bridge consists of approximately 43 feet of predominately clayey silty gravel with some silty and sand fill materials which were in turn underlain by approximately 35 feet of medium stiff to stiff Bay Mud. Below the Bay Mud, predominately very stiff silty clay soils with some sand lenses were encountered extending to the maximum depth explored of 123 feet. The fill thickness varies from about 23 to 43 feet. This extremely different thickness can occur within short distances and are typical of conditions where a mudwave has occurred. Mudwaves occur when fill is placed on a soft Bay Mud; when too much fill is placed in too short a time, a bearing capacity failure occurs. The approximate location of the testing borings is shown on Figure 2. Bayview Gateway Project Boring B-2(Treadwell & Rollo), drilled at the south abutment of Illinois Street Bridge encountered about 13 feet of loose to mediumm dense sandy gravel and medium stiff to stiff sandy clay fill. Approximately 12 feet of Bay Mud was encountered below the fill, which in turn is underlainn by 12 feet of medium to very densee gravel. Because Bay Mud was encountered between fill layers, it is likely the Bay Mud is fill or was displaced by fill placed during channel dredging. Below the gravel fill is natural Bay Mud, approximately 21 feet thick. A layer of dense to very dense sand with silt approximately 28 feet thick was encountered below the Bay Mud. The sand is underlainn by very stiff clay (Old Bay Clay) to the maximum depth explored of 91.5 feet. Boring B-18 (AGS, Inc.), was drilled approximately 40 feet south of the southern abutment of Third Street Bridge consists of approximately 23 feet of predominately clayeyy gravel and silty clay fill, which is in turn underlain by approximately 36 feet of medium stiff Bay Mud. The Bay Mud was in turn underlain by very stiff silty clay soils extending to the maximum depth explored of feet. The approximate location of the testing borings is shown on Figure 2. Groundwater Condition After the completion of soil boring, groundwater was measured in Borings B-1 and B-2 at levels of approximately 5.55 to 6 feet below the ground surface at the bridge abutments. This level may not represent a stabilized groundwater level; we expect groundwater levels in the area are controlled by the tidal variations in the channel. Groundwater should be assumed as much as 3 to 4 feet above sea level. Location Table 1 Summary of Test Borings Boring Designation Depth to Bottom of Fill (feet) Depth to Bottom of Bay Mud (feet) Depth to Bottom of Boring (feet) Tulare Park B-1* AGS B-17** Bayview Gateway B-2* AGS B-18** Note * Borings drilled at Illinois Street Bridge ** Borings drilled at Third Street Bridge San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

4 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 4 of 10 Table 1 summarizes the test boring including elevations of the bottom of fill, Bay Mud, and borings. An idealized subsurface profile along the Illinois Street Bridge alignment is shown on Figure 3 and the previous boring logs for the Illinois Street and Third Street Bridges are included and shown on Appendix A. Pile Foundations Considering the presence of poor quality heterogeneous fill and weak, compressible Bay Mud at both project sites, we conclude the proposed pedestrian walkway and boardwalk be supported on driven piles. The piles should extend throughh the fill and weak Bay Mud, which are unsuitable for support, and gain support in the stiffer and denser soil below. Piles should gain support primarily in end bearing in the dense to very dense sand, roughly 130 feet below the existing ground surface at Tulare Park and 70 feet below the existing ground surface at Bayview Gateway. Because of the thickness and consistency of the competent sandy soil below the Bay Mud varies greatly from one location to another, we expect significant variations in pile lengths. It is our opinion that steel pipe pile may be used because the use of steel pipe pile permits flexibility of cutting off and adding on without compromising pile integrity, and can significantly reduce pile waste. Therefore, we are presenting recommendations for steel pipe piles in this memorandum. Pipe piles can be driven either open end or closed end. When driven open end, soil is allowed to enter the bottom of the pipe. If an empty pipe is required, a jet of water or an auger can be used to remove the soil inside following driving. Closed end pipe piles are constructed by covering the bottom of the pile with a steel plate or cast steel shoe. In some cases, pipe piles are filled with concrete to provide additional moment capacity or corrosion resistance. However, this is generally not done in order to reduce the cost. In thesee cases corrosion protection is provided by allowing for a sacrificial thickness of steel or by adopting a higher grade of steel. If a concretee filled pile is corroded, most of the load carrying capacity of the pile will remain intact due to the concrete, while it will be lost in an empty pile. The structural capacity of pipe pile is primarily calculated based on steel strength and concrete strength (if filled). An allowance is made for corrosion depending on the site conditions. Open-Ended Pipe Piles It is our opinion that open-endedd pipe piles may be used to provide support for the proposed pedestrian walkway and boardwalk. The open-ended pipe piles are non-displacement foundation elements as a result of reducing ground heaving such that it is unlikely to disturb the existing PUC sewer force main and other utilities in the close proximity. The pipe piles gain their axial capacity in friction along the shaft. Based on the results of our analyses, the piles need to be installed a minimum of 10 feet into very dense sand or receive refusal. Refusal should meet the requirements as discussed in detail in project drawings and specification; in general, refusal can be defined as when the pile installation blow count becomes less than six inches of penetration in fifty (50) blow counts. San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

5 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 5 of 10 Since the existing utilities run through the project areas, to reduce vibrations during pile driving, pipe piles should be pre-drilled through the fill and Bay Mud to a depth of at least 25 feet to protect the existing utilities against disturbance. The diameter of the predrilled hole should not be greater than the nominal width of diameter of the pile. Pre-drilling will also reduce pile breakage through the fill, and maintain pile alignment. We also recommend the pipe piles be located a minimumm of 10 feet from the existing sewer force main. Due to the sloping bearing layer, pipe pile lengths will decrease from Tulare Park to Bayview Gateway; precise pile lengths cannot be determined priorr to driving. For estimating purposes, we recommend the bottom of Bay Mud is approximately 120 feet below the existing ground surface at Tulare Park and 60 feet below the existing ground surface at Bayview Gateway. The pipe piles can be designed for an allowable capacity of 200 kips in compression at Tulare Park and 100 kips in compression at Bayview Gateway with one-third increase for the seismic loads assuming the piles are driven to refusal of 10 feet below the top of the very dense sand layers. Based on the results of our analyses, the pipe piles should have a minimum spacing of 3 pile diameter center to center. It should note that if new fill is placed, the pipe piles will be subjected to downdrag loads, and pile capacities will be reduced due to the effect of downdrag. The structural capacity of the pipe piles needs to be confirmed by the project structural engineer. Lateral Resistance The pipe piles generally develop lateral resistance from the passive pressure acting on the upper portion of the piles and their structural rigidity. We developed load versus deflection and load versus moment curves based on a full section for both free-head and fixed-head condition for a 24-inch diameter pipe pile. The profiles of deflection, moment, and shear in the pipe pile for a range of lateral loads were generated. These profiles are presented in Figures 5 and 6 for Tulare Park and Figures 7 and 8 for Bayview Gateway. These lateral capacities are for single pipe pile only. Pile installed in a group of two spaced at least 3 pipe pile diameter center to center willl not adversely affect the pile resistance and capacity. Pile Test Program The objective of the pile test program is to: (1) validate the design assumptions used in the pile fictional shaft resistance and end bearing capacity, and (2) validate the pile head lateral deflection predictions under applied horizontal loads. Additionally, the success of installation method, particularly if pre-drilling is used is highly dependent on the performance of the pre- drilling in the fill layer. Pile test program will provide opportunities for the contractor to: (3) gain site experience at the project site; (4) develop acceptablee drilling and installationn methods to install test piles, and; (5) finalize the means and methods that will be used to install the production piles. We recommend at least one test pile be driven at each project site to observe the driving characteristics of the piles and the performance of the driving equipment. The test pile will provide blow count data to correlate with information obtained from the test borings, to aid in evaluating pre-drilling requirements and to be used as the basis for establishing final pile lengths. We also recommend using the same hammer type to drive the test and production piles. San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

6 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 6 of 10 Pile Installation Determination of driving equipment for this project should take into account the matching of the pile hammer with the pile size and length. Special consideration should be given in selecting a hammer that can deliver enough energy to the tip of the piles to drive them efficiently without damagingg them. Pile driven with impact hammers shall be fitted with a helmet to distribute the hammer blow uniformly and concentrically to the pile head. The surface of the helmet in contact with the pile shall be plane and smooth and shall be aligned parallel with the hammer base and the pile head. For pipe piles which are approximately round sections are frequently driven using square helmets. If the helmet dimension is much larger than the pipe diameter, then a centering fixture is required. Appropriate driving heads, mandrels, or other devices shall be provided so that the piles may be driven without damage. Pipes installed open-ended may require a suitable cutting shoe. Pile shoes used at the option of the Contractor shall be of a type approved by the Engineer. TORQUE DOWN PILES It is our opinion that Torque Down piles may also be used because of its ability to unobtrusively install in close proximity to the existing sewer force main and other utilities. We recommend the torque down pile be located a minimum of 10 feet from the existing sewer force main. The Torque Down piles are displacement foundation elements and are screwed in place. The Torque Down piles gain their axial capacity both in friction along the shaft and end bearing. The majority of its capacity would be derived from end bearing in the very dense sand. The Torque Down 1275 pile is a full displacement pile consisting of a concrete filled, inch outside diameter steel pipe with a closed end conical tip welded to the bottom of the pipe. The steel pipe pile thickness is typically 3/8 inch. The piles are advancedd or screwed into the ground by application of torque and the weight of the drill rig. An advantage of the Torque Down 1275 system is to size the piles in the field becausee of the easee of adding on or subtracting to each pile during installation. A significant advantage is the displacement method of installation whichh typically results in very little construction spoils. Because the piles are installed using a displacement method, the presence of groundwater will not have an effect on installation and the installation results in little or no vibration. Similar to pipe pile, the torque down piles need to be installed a minimum of 10 feet into very dense sand or receivee refusal. Refusal will be defined as when the pile installation rate becomes less than one foot of penetration in ten (10) minutes, or when the torque required to install the pile exceeds 200,0000 foot-pounds. The torque down piles can be designed for an allowable capacity of 160 kips in compression and 80 kips in tension at Bayview Gateway and 80 kips in compression and 40 kips in tension at Bayview Gateway with one-third increase for the seismic loads. The structural capacity of the piles needs to be confirmed by the project structural engineer. Based on the results of our analyses, the torque down piles should have a minimum spacing of 3 pile diameter center to center. San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

7 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 7 of 10 Lateral Resistance The Torque Down 1275 pile generally develops lateral resistance from the passive pressure acting on the upper portion of the piles and their structural rigidity. We developed load versus deflection and load versus moment curves based on a full section for both free-head and fixed- and shear in the pile for a range of lateral loads were generated. These profiles are presented in head condition for a inch diameter Torque Down Pile. The profiles of deflection, moment, Figures 9 and 10 for Tulare Park and Figures 11 and 12 for Bayview Gateway. These lateral capacities are for single pile only. Pile installed in a group of two be spaced at least 3 feet center to center will not adversely affect the pile resistance and capacity. Pile Test Program We recommend at least one test pile be installed at each project site to observe the installation characteristics of the piles and the performance of the equipment. The test pile will provide data to correlate with information obtained from the test borings, to aid in evaluating pre-drilling requirements and to be used as the basis for establishing final pile lengths. We also recommend using the same equipment to install the test and production piles. Corrosion Mitigation Measuress Bay Mud is considered potentially highly corrosive up to 20 feet below mud line. When pile is used in corrosive soil, special corrosion protection considerations for the steel pile may be needed. It is recommended that corrosion protection mitigation may include by allowing for a sacrificial thickness of steel in the upper portion of pile or by adopting a higher grade of steel and needs to be confirmed by the project structural engineer. Seismic Design Criteria The San Andreas Fault (Type A Fault as defined by the California Building Code) is the major active fault closest to the site. The main trace of the San Andreas Fault is situated about 12 kilometers southwest of the project site. For design in accordance with the 2010 California Building Code, we recommend the following: Peak Ground Acceleration (pga) for the Design Basis Earthquake (10% probability of exceedance in 50 years) of 0.48g. Site Class E Coefficients S MS of 1.35g and S M1 of 1.58g. Coefficients S DS of 0.90g and S D1 of 1.05g. Site Coefficients F a of 0.90 and F v of Construction Monitoring We recommend that the project geotechnical engineer review plans and specifications with regard to foundation and earthwork elements prior to construction bidding, in order to provide comments on the geotechnical aspects of the project. We further recommend that a representative of the geotechnical engineer be present to observe the pile test program and installation of the piles for the project. San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

8 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 8 of 10 Pile installation will cause excessive noise and vibration and will adversely impact at the existing structures adjacent to the site, specifically the PUC sewer force main should be monitored for pile driving induced-displacement at various locations on structures. To evaluate the effects of vibrations during and vibrations during pile installation. Survey points should be established driving, ground vibration monitoring should be performed on adjacent structures. If excessive vibrations are recorded, pile driving operations should be halted and different methods of installation should be considered. Peak particle velocity at the ground surface in front of the adjacent structures should not exceed 0.1 inch per second or any site constraints per project requirements. All active utilities within the construction area should be protected during construction. We recommend the existing facilities within the influence zones of the proposed construction be protected from disturbance or damage prior to construction activities. Limitations No field investigationn was performed for this memorandum. The geotechnical discussions and recommendations made in this memorandumm are based on the assumption that the soil conditions do not deviate appreciably from those encountered in previous test borings by others. Furthermore, our evaluation is limited to the geotechnical aspects of the project and did not include evaluation of structural or environmental issues or presence of hazardous material at the site. The recommendations presented in this memorandum were developed with the Standard of Care commonly used as the state of the practice in the profession. No other warranties are included, either expressed or implied, as to the professional advice included in this memorandum. San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

9 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 9 of 10 FIGURES San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

10 Tulare Park Bayview Gateway July 2013 Contract No. 1781J SITE LOCATION MAP Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 1

11 Tulare Park Bayview Gateway Approximate Location of Test Borings by AGS, February 2000 Approximate Location of Test Borings by Treadwell & Rollo, May 1997 and August 2001 Approximate Location of Test Borings by Treadwell & Rollo, January 2004 Approximate Location of Test Borings by Treadwell & Rollo, April 2004 July 2013 Contract No. 1781J VICINITY MAP Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 2

12 NOTE: 1. Idealized subsurface profile was prepared by Treadwell & Rollo, dated December The above profile represents a generalized soil cross section interpreted from widely spaced borings. Soil deposits may vary in type, strength, and other important properties between points of exploration. IDEALIZED SUBSURFACE PROFILE ALONG ILLINOIS STREET BRIDGE IN THE VICINITY OF TULARE PARK Bayview Gateway and Tulare Park July 2013 Improvement Project Project No. 1781J San Francisco, California FIGURE 3

13 NOTE: 1. Idealized subsurface profile was prepared by Treadwell & Rollo, dated December The above profile represents a generalized soil cross section interpreted from widely spaced borings. Soil deposits may vary in type, strength, and other important properties between points of exploration. IDEALIZED SUBSURFACE PROFILE ALONG ILLINOIS STREET BRIDGE IN VICINITY OF BAYVIEW GATEWAY Bayview Gateway and Tulare Park July 2013 Improvement Project Project No. 1781J San Francisco, California FIGURE 4

14 Depth, feet T&R B-1 (~ ) FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pipe pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-1) in the site vicinity Shear (kip) FREE HEAD SUMMARY OF NUMERICAL ANALYSES OPEN-ENDED PIPE PILE (Do = 24") for TULARE PARK July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 5

15 Depth, feet T&R B-1 (~ ) FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pipe pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-1) in the site vicinity Shear (kip) FIXED HEAD SUMMARY OF NUMERICAL ANALYSES OPEN-ENDED PIPE PILE (Do = 24") for TULARE PARK July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 6

16 T&R B-2 (~ ) Depth, feet FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pipe pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-2) in the site vicinity Shear (kip) FREE HEAD SUMMARY OF NUMERICAL ANALYSES OPEN-ENDED PIPE PILE (Do = 24") for BAYVIEW GATEWAY July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 7

17 T&R B-2 (~ ) Depth, feet FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pipe pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-2) in the site vicinity Shear (kip) FIXED HEAD SUMMARY OF NUMERICAL ANALYSES OPEN-ENDED PIPE PILE (Do = 24") for BAYVIEW GATEWAY July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 8

18 Depth, feet T&R B-1 (~ ) FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-1) in the site vicinity Shear (kip) FREE HEAD SUMMARY OF NUMERICAL ANALYSES TORQUE DOWN PILE (Do = 12.75") for TULARE PARK July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 9

19 Depth, feet T&R B-1 (~ ) FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-1) in the site vicinity Shear (kip) FIXED HEAD SUMMARY OF NUMERICAL ANALYSES TORQUE DOWN PILE (Do = 12.75") for TULARE PARK July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 10

20 T&R B-2 (~ ) Depth, feet FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-2) in the site vicinity Shear (kip) FREE HEAD SUMMARY OF NUMERICAL ANALYSES TORQUE DOWN PILE (Do = 12.75") for BAYVIEW GATEWAY July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 11

21 T&R B-2 (~ ) Depth, feet FILL BAY MUD Bending Moment (kip-ft) Deflection (inch) Notes: kips axial load and 20 kip-ft bending moment applied to head of pile. 2. Passive resistance of pile caps/footing has not been included. 3. Soil Profile based on existing boring (T&R B-2) in the site vicinity Shear (kip) FIXED HEAD SUMMARY OF NUMERICAL ANALYSES TORQUE DOWN PILE (Do = 12.75") for BAYVIEW GATEWAY July 2013 Project No. 1781J Bayview Gateway and Tulare Park Improvement Project San Francisco, California FIGURE 12

22 Bayview Gateway and Tulare Park Improvements Project August 2013 Page 10 of 10 APPENDIX A (Previous Boring Logs) San Francisco Department of Public Works Making San Francisco a beautiful, livable, vibrant, and sustainable city.

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