COASTAL BLUFF EVALUATION AND GEOTECHNICAL BASIS OF … · Geotechnical Engineering Coastal Engineering Maritime Engineering 3890 Murphy Canyon Road, Suite 200 San Diego, California

COASTAL BLUFF EVALUATION AND GEOTECHNICAL BASIS OF DESIGN

EMERGENCY UPPER BLUFF STABILIZATION

ANACAPA HALL, UC SANTA BARBARA

SANTA BARBARA, CALIFORNIA

Prepared for UNIVERSITY OF CALIFORNIA

SANTA BARBARA Santa Barbara, California

Prepared by TERRACOSTA CONSULTING GROUP, INC.

3890 Murphy Canyon Road, Suite 200 San Diego, California 92123

(858) 573-6900

Project No. 2911-01 July 17, 2017

Geotechnical Engineering

Coastal Engineering

Maritime Engineering

3890 Murphy Canyon Road, Suite 200 San Diego, California 92123 (858) 573-6900 voice (858) 573-8900 fax www.terracosta.com

Project No. 2911-01 July 17, 2017 Ms. Alissa Hummer, Director Campus Planning & Design UNIVERSITY OF CALIFORNIA, SANTA BARBARA

Santa Barbara, California 93106-1030 COASTAL BLUFF EVALUATION AND GEOTECHNICAL BASIS OF DESIGN EMERGENCY UPPER BLUFF STABILIZATION


SANTA BARBARA, CALIFORNIA Dear Ms. Hummer: TerraCosta Consulting Group, Inc. (TerraCosta) is pleased to submit the accompanying report, which describes our geotechnical and geologic evaluation of the coastal bluff erosion and instability affecting the subject property, as well as potential impacts to Lagoon Road, and presents recommendations for mitigation of these conditions. In addition, we have included input for the project’s Environmental Impact Study. We appreciate the opportunity to be of service and trust this information meets your needs. If you have any questions or require additional information, please give us a call. Very truly yours, TERRACOSTA CONSULTING GROUP, INC. _______________________________ Walter F. Crampton, Principal Engineer Braven R. Smillie, Principal Geologist R.C.E. 23792, R.G.E. 245 C.E.G. 207, P.G. 402 WFC/BRS/MWE/jg Attachments cc: Ms. Leslea Meyerhoff

UNIVERSITY OF CALIFORNIA, SANTA BARBARA July 17, 2017 Project No. 2911-01

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TABLE OF CONTENTS

1 INTRODUCTION ....................................................................................................................... 1

2 PHYSIOGRAPHY AND GEOLOGY ....................................................................................... 2 2.1 Physiography ..................................................................................................................... 2 2.2 Regional Geology ............................................................................................................. 2 2.3 Local Geology ................................................................................................................... 2 2.4 Site and Subsurface Conditions ........................................................................................ 3

2.4.1 Site Conditions ...................................................................................................... 3 2.4.2 Subsurface Conditions .......................................................................................... 3

2.5 Groundwater and Site Drainage ........................................................................................ 4 2.6 Faulting and Seismicity ..................................................................................................... 5

3 COASTAL ENVIRONMENT ................................................................................................... 6

4 COASTAL BLUFF EROSION .................................................................................................. 7

5 GEOLOGIC HAZARDS .......................................................................................................... 11 5.1 Introduction ..................................................................................................................... 11 5.2 Geologic Hazards Associated with Earthquakes ............................................................. 12

5.2.1 General ................................................................................................................ 12 5.2.2 Ground Rupture .................................................................................................. 12 5.2.3 Ground Shaking .................................................................................................. 12 5.2.4 Tsunamis and Seiches ......................................................................................... 13 5.2.5 Liquefaction and Lateral Spreading .................................................................... 13 5.2.6 Seismic-Induced Slope Instability ...................................................................... 14

5.3 Landslides ....................................................................................................................... 14 5.4 Seismic Induced Settlement ............................................................................................ 14 5.5 Collapsible Soils ............................................................................................................. 14 5.6 Expansive Soils ............................................................................................................... 15 5.7 Corrosive Soils ................................................................................................................ 15 5.8 Groundwater ................................................................................................................... 15

6 EXISTING BLUFF STABILITY ............................................................................................ 15 6.1 Introduction ..................................................................................................................... 15 6.2 Soil Conditions ................................................................................................................ 16 6.3 Groundwater Conditions ................................................................................................. 17 6.4 Slope Stability Analyses of the Existing Slope ............................................................... 17

6.4.1 Existing Bluff Stability Analysis - Static ............................................................ 17 6.4.2 Exiting Bluff Stability Analysis - Pseudo-Static ................................................. 18


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(continued)

7 PROJECT REMEDIATION ................................................................................................... 18 7.1 Introduction ..................................................................................................................... 18 7.2 Alternatives Analysis ...................................................................................................... 20

7.2.1 Bluff Stabilization: Structural-Tied-Back Wall at Face of Existing Bluff .......... 21 7.2.2 Bluff Stabilization: Structural-Tied-Back Structural Wall Recessed Into Face

of Existing Bluff ................................................................................................. 21 7.2.3 Bluff Stabilization: Tied-Back Drilled Pier Wall ................................................ 22 7.2.4 Rock Riprap ........................................................................................................ 22 7.2.5 Chemical Grouting .............................................................................................. 23 7.2.6 Groundwater Controls, Irrigation Restrictions, and Drought-Tolerant Planting. 24 7.2.7 Abandon Lagoon Road and Reroute Traffic Westerly of Anacapa Hall ............ 24 7.2.8 Underpinning ...................................................................................................... 24 7.2.9 No Project ........................................................................................................... 25

7.3 Preferred Alternative ....................................................................................................... 25

8 GEOTECHNICAL RECOMMENDATIONS FOR PREFERRED ALTERNATIVE ....... 25 8.1 General Earthwork .......................................................................................................... 25 8.2 Tieback Design Loads ..................................................................................................... 26

8.2.1 Remediated Bluff Preferred Option Stability Analysis-Static ............................ 26 8.2.2 Remediated Bluff Preferred Option Stability Analysis-Pseudo Static ................ 26

8.3 Tieback Requirements ..................................................................................................... 26 8.4 Wall Drainage ................................................................................................................. 27 8.5 Reinforced Concrete ....................................................................................................... 27

9 GENERAL CONSTRUCTION METHOD FOR PREFERRED COASTAL BLUFF REMEDIATION ....................................................................................................................... 27

10 LIMITATIONS ......................................................................................................................... 28

REFERENCES TABLE 1 FAULTS & CORRESPONDING GROUND MOTION CHARACTERISTICS


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(continued) FIGURE 1 VICINITY MAP FIGURE 2 GOOGLE EARTH VICINITY MAP FIGURE 3 EXISTING CONDITION SITE PLAN FIGURE 3 SITE MAP FIGURE 4 REGIONAL GEOLOGY MAP FIGURE 5 CHANNEL ISLANDS FIGURE 6 BEACH OSCILLATIONS FIGURE 7 SHORELINE CHANGE RATES FIGURE 8a BEACH PROFILE PRE-1982-83 EL NINO FIGURE 8b BEACH PHOTO - WINTER 1983 FIGURE 9 BEACH PHOTO - TYPICAL WINTER PROFILE FIGURE 10 BLUFF FACE ADJACENT LAGOON ROAD & ANACAPA HALL FIGURE 11 TSUNAMI INUNDATION MAP FOR EMERGENCY PLANNING FIGURE 12 EXISTING GENERAL CROSS SECTION FIGURE 13 PLAN VIEW WITH SLOPE STABILITY SUMMARY FIGURE 14 SUMMARY OF STATIC SLOPE STABILITY-EXISTING CONDITION FIGURE 15 SUMMARY OF PSEUDO-STATIC SLOPE STABILITY-EXISTING CONDITION FIGURE 16 CONCEPTUAL REPAIR ALTERNATIVE NO. 1 FIGURE 17 CONCEPTUAL REPAIR ALTERNATIVE NO. 2 FIGURE 18 CONCEPTUAL REPAIR ALTERNATIVE NO. 3 APPENDIX A FUGRO WEST JANUARY 2006 REPORT APPENDIX B RESULTS OF EQFAULT SEARCH APPENDIX C RESULTS OF EQSEARCH SEARCH APPENDIX D SLOPE STABILITY RESULTS APPENDIX E DSI LITERATURE

UNIVERSITY OF CALIFORNIA, SANTA BARBARA July 17, 2017 Project No. 2911-01 Page 1

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COASTAL BLUFF EVALUATION AND GEOTECHNICAL BASIS OF DESIGN

EMERGENCY UPPER BLUFF STABILIZATION


SANTA BARBARA, CALIFORNIA

1 INTRODUCTION

This report addresses the emergency condition that exists along the existing coastal bluff adjacent to the University of California at Santa Barbara’s (UCSB) Lagoon Road, the primary traffic artery/corridor that services the campus in general, and Anacapa Hall. In addition to providing access for everyday traffic and operations for UCSB, Lagoon Road provides access for emergency vehicles, including fire trucks, to the eastern portion of the campus and, as such, is vital to the operation and functioning of the University. Anacapa Hall and Lagoon Road are located just landward of the eastern edge of the coastal bluff in Santa Barbara, California (see Figures 1 and 2).

Specifically, this report focuses on an approximate 50-foot section of the coastal bluff where the top of the bluff has encroached to within approximately 14 feet of Lagoon Road and within approximately 60 feet of the southeastern corner of Anacapa Hall. The bluff within this 50-foot section has an estimated static factor of safety of 1.2 or less, which extends approximately 14 feet into Lagoon Road. This area of marginally stable bluff threatens to disrupt the functioning of the campus by restricting campus traffic in general, and more specifically to limit, disrupt, and potentially cut off direct access to the eastern portion of the campus for emergency vehicles, including fire truck access, and also hinder and restrict access to Anacapa Hall. To further illustrate the severity of this situation, consider that a bluff-top failure does occur. The resulting failure would block access to Lagoon Road, thereby preventing vehicular traffic, including essential emergency vehicles, from accessing the eastern portion of the UCSB campus and disrupting and restricting the utilization of Anacapa Hall. Such an event would significantly impact and restrict the functioning of UCSB.



To address this emergency condition, our evaluation examines mitigation measures to address this emergency condition, and provides geotechnical recommendations and the basis of design for emergency bluff stabilization measures considered necessary to mitigate the top of the coastal bluff encroaching into and beyond Lagoon Road.

2 PHYSIOGRAPHY AND GEOLOGY

2.1 Physiography

The main campus of UCSB is located on the northern portion of an elevated mesa that is generally bounded by the Pacific Ocean to the south and east, the Goleta Slough to the north, and the residential community of Isla Vista and Devereux Slough to the west. The mesa has a gently undulatory surface, but is generally a flat-lying marine terrace elevated 30 to 50 feet above MSL. A 2015 Google Earth image (Figure 2) shows the campus with the community of Isla Vista immediately to the west. Figure 3 shows the area of immediate concern adjacent to Lagoon Road and Anacapa Hall where the lack of coastal bluff stability threatens these facilities.

2.2 Regional Geology

The project site lies within the Transverse Ranges California Geomorphic Province. This province is characterized by a series of east-west trending mountain ranges and valleys. The province extends to the east to the San Bernardino Mountains and offshore to the west to the Channel Islands of San Miguel, Santa Rosa, and Santa Cruz. The east-west structure is oblique to the normal northwest trend of the California coastline. The regional geology of the site and vicinity is shown on Figure 4.

2.3 Local Geology

The approximately 45-foot-high coastal bluffs in the study area are comprised of upper Miocene Sisquoc Formation capped with upper Pleistocene marine terrace deposits. The Sisquoc Formation consists primarily of laminated diatomaceous mudstone, shale, and dolomite, and local conglomerate. Deposits within the Sisquoc Formation are believed to be derived from the Monterey Formation (Minor, et al., 2003). The upper Pleistocene marine terrace deposits are described as consisting of pale to medium tan, brown, and gray, weakly



to moderately consolidated, crudely to moderately bedded pebble, cobble, gravel, and conglomerate sands and sandstone, and silt and siltstone. These deposits unconformably overlie eroded bedrock on the elevated marine wave-cut abrasion platform.

Based on our review, borings from the January 2006 Fugro West, Inc. geotechnical investigation conducted for the Ocean Science Education Building located approximately 350 feet to the north-northwest of the subject site encountered the contact between the upper Pleistocene marine terrace and the underlying Sisquoc Formation ranges between 29 and 31 feet MSL. A copy of the January 2006 Fugro West, Inc. report is provided in Appendix A.

2.4 Site and Subsurface Conditions

2.4.1 Site Conditions

The site conditions are comprised of Anacapa Hall, the landscaped areas from Anacapa Hall to Lagoon Road, Lagoon Road, the landscaped areas between Lagoon Road and the coastal bluff, and the coastal bluff itself. The southeast corner of Anacapa Hall is located approximately 60 feet from the top of bluff, and the eastern edge of Lagoon Road is located approximately 14 feet from the top of the bluff.

The topography is relatively flat, with ground surface elevations ranging from 44 to 46 feet MSL. Site drainage is generally to the south, except for that portion from the top-of-bluff to the bluff face where the drainage is directed over the slope.

2.4.2 Subsurface Conditions

TerraCosta did not perform any geotechnical investigation for this project. Instead, we reviewed several reports prepared by Fugro, which provided data concerning subsurface conditions at and within the site vicinity. A list of reports reviewed is presented at the end of this report under References. The information and data presented in these reports were interpreted for our use. Based on our review, the subsurface conditions at the site consist of a relatively thin layer of surface fills that overlie terrace deposits. These deposits are underlain by materials comprising the Sisquoc Formation. The terrace deposits and Sisquoc Formation are exposed and visible in the coastal bluff face adjacent to Lagoon Road.



Geologic units found at the site are briefly described below:

Artificial Fill: The artificial fill material is associated with the construction of the existing structures and improvements. These materials are generally comprised of pavement materials and silty sand. It is difficult to distinguish the fill materials from the underlying terrace deposits, which results in an uncertain determination of general thickness. The fill materials are anticipated to be less than 3 to 5 feet in thickness throughout the project area. However, there is the possibility of thicker deposits locally. These thicker deposits are more prone to be found in areas of utility corridors, planter areas, and other areas where deeper excavation into the top of the terrace deposits has occurred.

Terrace Deposits: The terrace deposits within the project site generally extend to a depth of 10 to 15 feet below the ground surface, with the contact between them and the underlying Sisquoc Formation being encountered between elevations 29 and 35 feet MSL, with an average elevation of approximately 30 feet MSL. The deposits are generally comprised of loose to medium dense silty sands, with zones of sandy silts and the occasional layer of sandy lean clay.

Sisquoc Formation: The Sisquoc Formation underlies the terrace deposits. The elevation of the contact in the project vicinity ranges from +29 to +35 feet MSL, with an average elevation of +30 feet MSL. In their January 2006 report, Fugro states that the formation extends approximately 20 to 40 feet below the ground surface. However, they do not state the elevation of the lower contact, nor the material that underlies the Sisquoc Formation. In their stability analyses, they assumed the Sisquoc Formation to the depth of their analytical section. The Sisquoc Formation is described as a massive, highly to moderately weathered, poorly indurated, fractured/jointed claystone to clayey siltstone. This formation is known to contain locally thin beds of very hard siliceous material. In addition, it is common to find, often at the contact with the overlying terrace deposits, a zone of extremely to highly weathered claystone to clayey siltstone whose thickness is on the order of 2 to 5 feet, which generally has lower compressive strength and is generally more compressible.

2.5 Groundwater and Site Drainage

Site drainage is generally to the south and toward Lagoon Road, except adjacent to the bluff where it drains toward the bluff face and over the bluff.



Seeps and spring sapping were observed in the bluff face just above the contact between the capping marine terrace deposits and the Sisquoc Formation, estimated to be near elevation 30 feet MSL.

From our review of the available reports (Fugro, 2006 and 2016), groundwater was encountered perched onto of the Sisquoc Formation and near elevations 33 to 35 feet.

2.6 Faulting and Seismicity

Faulting in the general area is controlled by the regional tectonic compressive forces that have resulted in generally east-west trending faults, with associated northeast and northwest splays. Fault displacement is generally believed to be predominantly vertical, with general upthrown southern blocks.

No faults are known to cross or pass through the site. However, there are numerous faults within the vicinity of the site. Two faults mapped near the site include the Campus Fault and the More Ranch Fault. The closest horizontal distance to the project site is approximately 1,660 feet for the Campus Fault, and 3,260 feet for the More Ranch Fault. Both of these fault strands are reported to be associated with the More Ranch Section of the Mission Ridge Fault System.

To assess the relative significance of nearby faults near the site, we used the computer program EQFAULT 3.0 to search the California Division of Mines fault database for faults located within 100 miles of the site. Results of that search are presented in Appendix B of this report. A summary of the more significant faults, as assessed by their estimated peak ground acceleration associated with their maximum earthquake, is presented in Table 1. Two faults of significance, as measured by their estimated peak ground acceleration, are the North Channel Slope Fault and the Mission Ridge-Arroyo Parida-Santa Ana Fault. The estimated peak ground accelerations for their corresponding maximum earthquake are approximately 0.8g for the North Channel Slope Fault and 0.6g for the Mission Ridge-Arroyo Parida-Santa Ana Fault.

Another measure for evaluating seismic exposure to a site is to assess the number of historical earthquakes that have occurred near the site. To assess the historical earthquakes that have likely impacted the site, we used the computer program EQSEARCH 3.00 and searched the historical earthquake records from the year 1800 to 2011 for earthquakes that



have occurred within 100 miles of the site. Results of that search are presented in Appendix C of this report. From this historical record, the highest estimated peak ground acceleration that occurred at the site is estimated to be approximately 0.36g. This event is reported to have occurred in 1862, and to have occurred approximately 1.4 miles from the site. Two other historical events are estimated to have produced peak ground accelerations above 0.2g. These are reported to have occurred in 1812 and 1925 and within 15 miles of the site.

One other measure of site seismicity would be the corresponding California Building Code-based estimate of peak ground acceleration for the Maximum Considered Earthquake and the code-specified design earthquake, which are estimated to be 1.2 and 0.82, respectively.

3 COASTAL ENVIRONMENT

The shoreline along UCSB and Lagoon Road is located within the Santa Barbara Littoral Cell. The Santa Barbara Littoral Cell is one of the longest cells in southern California. The mouth of the Santa Maria River is currently used as the northern boundary of this cell. From there, the cell stretches 230 km toward the submarine canyon at Point Mugu. This canyon functions as an almost complete trap for the littoral drift, and can therefore be seen as the downdrift boundary of the cell. The 40 km wide Santa Barbara Channel separates the so-called Northern Channel Islands from the mainland (Figure 5). The Santa Rosa, Santa Cruz, San Miguel, and Anacapa Islands, together with the east/west orientation of the coastline, result in a wave climate in the Santa Barbara Channel that is less energetic than along most parts of the California coastline. The east/west orientation shelters the coastline from swell that predominantly comes from the west/north-western direction, while the Northern Channel Islands provide some shelter to the less frequently occurring southern swell (Barnard, et al., 2009).

Swells at the Santa Barbara Littoral Cell have a narrow directional window due to the change of coastline orientation and the sheltering effect of the Northern Channel Islands. In the Santa Barbara Channel, the wave climate is dominated by west/northwestern swells that occur 85 percent of the time. The less frequently occurring southern swell penetrates into the Santa Barbara Channel entrance between the Northern Channel Islands and Point Mugu. The Northern Channel Islands shelter most of the south-facing coastline from extreme wave



events. As a result, the wave climate along the coastline between Goleta and Oxnard is considered tranquil, with wave heights that rarely exceed 2 meters (Barnard, et al., 2009).

The south/southeastern swell direction ranges from 135°N to 195°N and contributes only 12 percent to the total dataset. The wave heights are, with a peak value of 4.4 m, lower than swells originating from the west/northwest. The peak periods are relatively higher for south/southeastern swells (~15.0 to 18.5 sec) than for west/northwestern swells (~10.0 to 18.0 sec) (Barnard, et al., 2009).

The majority of beaches within the Santa Barbara study area are narrow and ephemeral. The malnourished beaches continue to erode, resulting in a reduction of the dry beach width, an increase in damages by storm activity, and decreased recreational beach benefits. Isla Vista exhibited a long-term erosion (narrowing) trend over the last 70 years: the beach volume has been decreased by 50 percent from 80,000 m2 to 40,000 m2 (Barnard, et al., 2009).

The lack of sediment being transported around Campus Point prevents the beaches of UCSB and the part of Goleta Beach west to Goleta Slough to accrete.

4 COASTAL BLUFF EROSION

Coastal bluff retreat rates are conventionally expressed in inches per year of retreat by marine erosion at the intersection of the shore platform and the lower cliffed part of the bluff.

To the extent possible, bluff retreat rates should be estimated separately for:

• Coastal bluff headlands, absent localized zones of weakness such as sea caves and coves; and

• Sea caves, sea coves, and associated surge channels, which typically grow at accelerated rates along structural disparities (faults and joints in the rock).

Rates of erosion vary along this segment of coastline. These differential rates are likely aggravated by the extensive faulting and folding that weaken the bedrock. Numerous studies by various researchers indicate that the area around Isla Vista and UCSB have experienced very high rates of erosion over the last 50± years. Beach width oscillations around UCSB



and Goleta beaches (Figure 6) indicate that beaches had reached their maximum widths in the 1960s and 1970s, while current beach widths are similar to those found in the 1930s and 1940s (Barnard, et al., 2009).

The 2009 report by Barnard, et al., is a 926-page document titled, “Coastal Processes Study of Santa Barbara and Ventura Counties, California (USGS Open File Report 2009-1029).” This U.S. Geological Survey document systematically evaluated both long-term and short-term erosion rates of both the beach face and sea cliff along a 150 km section of coastline, with the Ellwood/Isla Vista/Goleta area in roughly the middle of the study area. Figure 7, reproduced from the 2009 USGS Open File Report, shows erosion hotspots between Ellwood and Goleta, with significant shoreline erosion noted throughout numerous areas along this section of coastline, including adjacent Anacapa Hall. While erosion rates reported on Figure 7 reference reductions in beach width, the USGS also indicated that hotspots of cliff erosion correlate to areas of decreased beach width and beach elevation over time scales of individual storms and storm seasons.

Inside of Campus Point and extending to Goleta Beach (including the section adjacent to Anacapa Hall), the shoreline orientation faces east-southeast where, in this area, the beach face changed the most dramatically before and after the 1982-83 El Niño storm season. The 1982-83 El Niño storm season decimated this beach, and this area has not yet recovered. Figures 8a and 8b illustrate the magnitude of the beach width change, which during the 1982-83 El Niño storm season scoured the protective sand beach, resulting in direct wave impact and localized erosion along this section of coastline, most notably adjacent to Anacapa Hall. This beach face has remained narrow since the 1982-83 El Niño storm season (refer to Figure 3), with increased coastal bluff erosion resulting from storms out of the south.

Figure 9 shows a typical winter profile along this section of UCSB today, with the erosion hotspot adjacent to Anacapa Hall shown on Figure 10, where today the top-of-bluff is about 14 feet from the Lagoon Road curbline, where water, sewer, and gas utilities are now threatened along this 50-foot section of coastline. Anacapa Hall is also currently approximately 60 feet from the top-of-bluff.

The assessments of coastal cliff retreat were conducted by several authors, including Griggs, et al. (2005); Hapke et al. (2009); Arthur Sylvester (1997 to 2012); Eva E. von Thury (2013); and Fugro (2016). The results of those studies are described below.



In Griggs, et al. (2005), two erosion rates were reported for the portion of the Santa Barbara coast along Lagoon Road. These erosion rates were 15 and 13 cm per year (converted from the reported inches per year values.)

In a separate study, Hapke, et al. (2009) suggests current average rates of coastal cliff retreat are locally on the order of 0.2 meter per year, where, along a 17 km section of coastline, Hapke and others profiled 828 transects, with an average transect spacing of about 80 feet (Hapke, et al., 2009).

Over the last 35 years, Arthur Sylvester has made field survey ground measurements along Lagoon Road. According to the reported June 2012 survey, calculated rates were 12.5 to 15 cm per year, with a maximum rate of 24.5 cm per year. It is important to note that some of the field posts used by Sylvester are missing and, as such, may have influenced his results. As such, his recent rate estimates may be lower due to this missing data.

As part of her 2013 thesis, von Thury assessed coastal erosion and sea-cliff retreat in southern Santa Barbara County. Part of her study included the portion of coast along Lagoon Road. A summary of the results of her study follows:

1. Using LIDAR datasets from 1998 to 2010, von Thury estimated erosion rates at select locations along the coast from Point Conception to Rincon Point to establish regional rates. Along the Lagoon Road segment next to Anacapa Hall, von Thury estimated rates for four locations. These rates were 16, 14, 39, and 25 cm per year from west to east.

2. In addition, using 1997 LIDAR and 2012 Direct Laser Scanning, von Thury estimated an average annual erosion rate along Lagoon Road of 24 cm per year, with values ranging from 10 to 35 cm per year. From the rates she estimated, she reported two erosion rates from just south and north of Anacapa Hall, which were 25 and 20 cm per year, respectively.

3. In addition, it was reported that, where the sea cliff was protected by riprap, erosion rates at the cliff edge (within the marine terrace) ranged from 10 to 15 cm per year. In addition, it was noted that the base of the cliff (Sisquoc Formation) immediately behind the riprap remained unchanged.



4. Comparison of the top-of-bluff showed that the unlithified marine terrace deposits retreated faster than the Sisquoc Formation. In addition, the majority of these measured erosion rates were associated with the effects of three major storms that occurred during the three winter months.

Lastly, Fugro (2016a and 2016b) assessed the erosion rate for a recent infrastructure project along Lagoon Road. As part of that project, Fugro responded to the California Coastal Commission’s (CCC) comments concerning their erosion rate assessment. A summary of Fugro’s work is presented below:

1. Fugro prepared a bluff-top setback report in 1999, which they believe is applicable for the subject project.

2. Fugro noted that the proposed project encroaches within the 100-year setback line between Stations 27+50 and 21+50.

3. The infrastructure impacted by this encroachment consists of Lagoon Road, a set of campus stairs to the beach, foot paths, Parking Lot 6, and buried utilities. The buildings located west of Lagoon Road are not located within the 100-year setback.

4. The 1999 Fugro study was based on historic air photo review, and site reconnaissance with mapping. The findings of that study noted that no large-scale failure of the slopes or significant bluff retreat had occurred between 1928 and 1997. In addition, their data suggested a bluff retreat of 5 cm/year for the period of time between 1967 and 1999.

5. For their current study, Fugro noted that there had been some areas of recent retreat and loss of ground in the upper section of the bluff in the terrace deposits. They also noted that these conditions were very similar to those observed during their overall bluff stability efforts reported in 1999 and 2000. Fugro noted that their findings were applicable to the Main Campus Infrastructure Renewal Project. However, they did concede that the findings of von Thury’s 2013 study should be incorporated into Fugro’s data.

6. Fugro noted that the von Thury study provided annual retreat rates for the Lagoon Road area averaging 24 cm/yr. They noted that as part of the von Thury study, average bluff retreat rates of 14 cm/yr along Lagoon Road were reported by Professor Sylvester. Fugro noted that the increased erosion rate from Fugro’s 1999 study and



von Thury’s 2013 study could be due to the potential increased accuracy in method used, as well as changes in coastal processes.

7. Given their review of von Thury’s work, Fugro revised the potential average rate of retreat to be on the order of 14 to 24 cm/year. Given this potential rate, Fugro noted that the proposed improvements associated with the Campus Infrastructure, assuming a distance of 25 feet, would be impacted in approximately 30 to 50 years, which is less than the 100-year setback requirement.

8. Fugro states that their bluff retreat rates, where modified from 5 cm/yr to 14 to 25 cm/yr, assumed no sea level rise. They note the CCC (2015) comment that, while there is no fully accepted approach for incorporating sea level rise into predictions of bluff retreat rate, the CCC does suggest that it might be reasonable to estimate future bluff retreat rates considering sea level rise by considering the higher-end range of currently estimated bluff retreat rather than historic average rate.

9. Fugro noted that UCSB has been subjected to periodic El Nino storm events that have resulted in temporary storm surges, elevated sea levels, and increased rates of bluff retreat and, as such, state that it would be reasonable to assume higher historic range of bluff retreat when considering sea level rise.

10. Given the above comments, Fugro reexamined the work of von Thury and Professor Sylvester, and noted that upper end retreat rates from these two sources ranged from about 30 to 40 cm/yr. They note that, at these rates, the proposed improvements could be impacted in 20 to 25 years. However, they note that erosion and surficial slumping of the older alluvial deposits that cap the bedrock are a significant component to the overall bluff retreat along the East Bluffs of the Campus and, given that the proposed projects will reduce the erosion potential of the older alluvial soils, the impacts associated with sea level rise may not be as significant.

5 GEOLOGIC HAZARDS

5.1 Introduction

In general, a project may be exposed to risks associated with various geologic hazards. Many of those hazards are related to the actions of earthquakes and faulting. In addition to



geologic hazards associated with earthquakes and faulting, there are other potential geologic hazards that may impact the proposed project. These include: landslides, expansive soils, collapsible soils, corrosive soils, and high or perched groundwater. A brief description of the various geologic hazards and their impact on the project site is presented below.

5.2 Geologic Hazards Associated with Earthquakes

5.2.1 General

Geologic hazards generally associated with earthquakes include ground rupture, ground shaking, tsunamis, seiches, seismic-induced flooding, liquefaction, seismic-induced ground settlement, and seismic-induced slope instability. With respect to these hazards, we have the following comments.

5.2.2 Ground Rupture

No known faults cross the project site. As such, it is our opinion that ground rupture due to faulting is not a hazard for this project.

5.2.3 Ground Shaking

The significance of ground shaking, as it relates to a geologic hazard, is associated with two issues. The most commonly understood issue pertains to the imparting of inertial forces into buildings and structures. The second issue, of equal significance, is related to the stability of the ground during ground shaking.

The characterization of ground shaking is oftentimes expressed in terms of either peak ground acceleration (PGA) or the response of a single degree of freedom oscillating mass for various periods or frequencies of motion to the ground shaking produced by an earthquake. This response is generally expressed in terms of a response spectrum that encapsulates the range of motions anticipated at the site for a given set of earthquake events.

According to the California Building Code, the earthquake scenario for consideration for the design of the proposed structures is based on the Maximum Considered Event (MCE). This event corresponds in general to an earthquake hazard having a 2 percent probability of exceedance in 50 years. Such an earthquake event is also often described as the 2,500-year



event. The design of the proposed structures is based on the design level earthquake whose corresponding response spectra is taken as two-thirds of the MCE response spectra.

Given the location of the site, the risk for ground shaking is considered very high.

5.2.4 Tsunamis and Seiches

Tsunamis and seiches are not considered likely hazards at this project site. A review of the State of California Tsunami Inundation Map for Emergency Planning (2009) indicates that the Lagoon Road site will be unaffected by tsunamis caused by both local and distant sources (see Figure 11). Likewise, the project site is not located within a bay where seiches might occur.

5.2.5 Liquefaction and Lateral Spreading

Three key ingredients are required for liquefaction to occur: liquefaction-susceptible soils, sufficiently high groundwater, and strong shaking. Liquefaction is the phenomena associated with ground shaking, which results in the increase of pore pressures within the soil. As the pore pressure increases, the shear strength of the soil is reduced. If the pore pressure is sufficiently increased, the soil takes on a “liquid like” behavior. Consequences commonly associated with soil liquefaction include ground settlements, surface manifestations (sand boils), loss of strength, and possible lateral ground movement typically referred to as lateral spreading, ground oscillations and lurching, and possible ground failure.

Soils susceptible to liquefaction generally consist of loose to medium dense sands and non-plastic silt deposits below the groundwater table.

At the project site, there is a zone of saturated granular soils within the terrace deposits located approximately 10 feet below the ground surface. These soils may be susceptible to liquefaction, with anticipated consequences believed to be limited to small settlements (less than 1 inch) and minor ground movements.

Lateral spreading is generally associated with sites where liquefaction is possible and where the ground surface is gently sloping, or when a free-face condition, such as a road cut or river bank, exists.



Review of available data indicates that the potential for lateral spreading is considered to be low, given the limited liquefaction hazard and the relatively level surface topography. However, the risk of lateral spreading should not be considered non-existent, given the site is adjacent to an existing coastal bluff.

5.2.6 Seismic-Induced Slope Instability

The susceptibility of slopes to seismic instability is generally addressed by the requirements of the governing agency. Given that the slopes in question fall under the purview of the CCC, we evaluated the risk associated with seismic stability under their general approach, which considers a slope sufficiently stable if the computed factor of safety of a slope is greater than 1.1 when subjected to a horizontal seismic coefficient equal to 0.15. Under this condition, the risk for impacts associated with seismic instability for the adjacent coastal bluffs is considered high.

5.3 Landslides

No landslides have been mapped in the area. However, the site is located adjacent to a coastal bluff that is actively retreating, which impacts the stability of the upper terrace deposits. Currently, the terrace deposits at the site are in a near-vertical condition and are in an impending failure condition. As such, improvements and structures near the top-of-bluff are considered at risk and are likely to be impacted in the near future.

5.4 Seismic Induced Settlement

Under cyclic loading due to earthquakes, loose to medium dense granular soils may undergo reduction in volume. This may result in seismic-induced settlement and differential compaction. However, the anticipated risk to seismic settlement and differential compaction is considered to be negligible.

5.5 Collapsible Soils

No collapsible soils were reported in the literature reviewed or nearby field investigation reports. As such, it is our opinion that the potential for collapsible soils is low.



5.6 Expansive Soils

No expansive soils were reported in the literature reviewed or nearby field investigation reports. It is therefore our opinion that impacts to the proposed project due to expansive soils are low.

5.7 Corrosive Soils

In general, marine environments are very corrosive by nature. Soils (and conditions) should be considered moderately to severely corrosive.

5.8 Groundwater

Based on our review of available reports (Fugro, 2006 and 2016), perched groundwater was encountered on the Sisquoc Formation near elevations 33 to 35 feet. In addition to this perched condition, we anticipate groundwater to be encountered within the Sisquoc Formation near MSL.

We anticipate that the upper perched groundwater table will be unaffected by sea level rise. However, given that the lower groundwater table at the site is influenced by the ocean, the groundwater table is anticipated to vary and track the level of water in the ocean. As such, this lower groundwater table is anticipated to vary from +5.5 feet to -3 feet MSL for current sea level conditions. Over time, this highest groundwater table elevation is likely to rise, given future anticipated sea level rise. According to the CCC in their August 12, 2015, Sea Level Rise Policy Guidance Document, sea level rise has been estimated at 0.25 foot to 2.25 feet over the next 50 years. If one assumes that the maximum sea level rise is 2.25 feet, the groundwater elevation is anticipated to fluctuate between -1 foot and +8 feet MSL. However, for design purposes, the maximum groundwater table (assuming high tides and storm surges) is estimated to be +10.5 feet over the next 50 years.

6 EXISTING BLUFF STABILITY

6.1 Introduction

In order to assess the stability of the upper bluff and the bluff in general, we performed stability analyses on a cross-section located through the coastal bluff face at the location of



greatest encroachment toward Lagoon Road (Figure 3). The approximate geologic cross section is shown on Figure 12.

6.2 Soil Conditions

The soil conditions represented in our stability analyses consist of an upper marine terrace layer that overlies the underlying Sisquoc Formation. The Sisquoc Formation is represented as three zones of material consisting of a 5-foot weathered zone at the contact between the upper terrace deposits and the Sisquoc Formation, and a 10-foot outer weathered zone of the coastal bluff itself and an unweathered interior zone of Sisquoc Formation.

The strengths of the various materials were developed from our review of previous analyses performed by Fugro (August 2016) and our experience with similar coastal bluff materials we have examined along the southern California coast. In Fugro’s analyses, they modeled the strength characteristics of the Sisquoc Formation using a Hoek-Brown criteria. We reinterpreted their model into a more traditional Mohr-Coulomb framework.

For our analyses, we used the following Mohr-Coulomb strengths:

Beach Deposits: φ = 30 degrees c = 0 psf γt = 100 pcf Terrace Deposits: φ = 32 degrees c = 150 psf γt = 120 pcf Weathered Sisquoc Formation at contact with terrace: φ = 32 degrees c = 600 psf γt = 130 pcf



Weathered Sisquoc Formation at outer face of bluff: φ = 33 degrees c = 600 psf γt = 130 pcf Sisquoc Formation: φ = 45 degrees c = 1,000 psf γt = 130 pcf These soil strengths represent saturated soil conditions that would result from long periods of high intensity rainfall. Soil strengths during typically dry periods are expected to be higher as a result of actual or apparent soil cohesion that exists due to the capillary tension that develops due to negative pore water pressure. We believe that it is appropriate to evaluate slope stability with the saturated strengths that trigger most of the slope failures in the area.

6.3 Groundwater Conditions

In our slope stability computations, we used two groundwater conditions. The first groundwater condition consisted of a perched groundwater table located within the terrace deposits and the weathered Sisquoc Formation at the contact between the upper terrace and Sisquoc Formation. The second groundwater condition was taken as occurring at Mean Sea Level in the lower portions of the coastal bluff.

6.4 Slope Stability Analyses of the Existing Slope

6.4.1 Existing Bluff Stability Analysis - Static

Results of our static slope stability for the existing slope indicate that the stability of the slope is dependent on the distance from the top-of-bluff. This is illustrated by Figures 13 and 14, which shows the portions of the slope that have a factor of safety near 1, between 1 and 1.2, between 1.2 and 1.5, and greater than 1.5.

The acceptability of slope stability depends on the agency under which the slope is assessed. For example, new fill and cut slopes are considered acceptable when the computed static factor of safety is equal to or greater than 1.5. Depending upon the agency, slopes located



along highways generally are oftentimes considered acceptable when the static factor of safety is greater than 1.3. With regards to coastal bluffs, it is our understanding that if the factor of safety is less than 1.2, the CCC generally considers that slope being in a potential emergency condition.

As illustrated in Figure 13, the slope is considered in a potential emergency condition from the top of the bluff to a distance of approximately 28 feet from the slope; in an acceptable condition (factor of safety greater than or equal to 1.3) for a highway that might fall under Caltrans jurisdiction for distances beyond 32 feet of the top of the bluff; and considered stable from a California Building Code perspective for new fill and cut slopes for distances greater than 38 from the top of the slope.

6.4.2 Exiting Bluff Stability Analysis - Pseudo-Static

Some agencies also evaluate the stability of a slope under earthquake or seismic conditions. The criteria used to assess a sufficiently stable condition depend upon the agency that has jurisdiction over a given slope. It is our understanding that the CCC considers a slope that has a factor of safety greater than 1.1 with a horizontal pseudo-static seismic coefficient of 0.15 as being satisfactory.

The results of our stability analyses under seismic conditions assuming that the CCC has jurisdiction, as shown in Figure 15, indicate a stable condition for improvements located 35 feet beyond the top of slope, and, for improvements located within 35 feet, the slope conditions do not satisfy the CCC criteria.

The results of our slope stability analyses are presented in Appendix D.

7 PROJECT REMEDIATION

7.1 Introduction

Accelerated coastal erosion along an approximately 50-foot section of coastal bluff has encroached to within about 14 feet from the easterly edge of Lagoon Road on the UCSB campus (Figure 3). Numerous utilities critical to the operation of the campus exist within Lagoon Road, and there is now concern over the potential loss of this critical infrastructure.



In addition, results of our stability analyses of the bluff indicate that a significant portion of the top-of-bluff area, including significant portions Lagoon Road which is critical to the operation of the University in general and specifically Anapaca Hall, is in a condition that the CCC would recognize as being in an emergency condition.

As such, we have had discussions with University Staff concerning ways in which this condition could be addressed and remediated. As part of our preliminary discussions with University Staff, in order to stabilize the coastal bluff, we recommended several bluff stabilization measures that would stabilize that portion of the bluff that threatens the immediate operation of Anacapa Hall, and the impending encroachment into Lagoon Road, which would impair University operations. During our discussions regarding various bluff stabilization measures, we inquired about the utilities located within Lagoon Road, as those utilities could impact the location of any tieback anchors that would be necessary for the stabilization measures. As we understand, while the University has fairly good as-built records defining the locations of all of the existing utilities, they do not have accurate records of the depths of these utilities. University personnel indicated, however, that there are no utilities more than 15 feet below existing grade, whether underneath or seaward of Lagoon Road.

Bluff stabilization measures include the following options:

1. A tied-back structural skin placed at the current face of the bluff and extending from the top of the bluff to the base where it is embedded 2 feet into the formational materials comprising the shore platform (see Figure 16). The tied-back structural shotcrete wall system would be reinforced to accommodate a 15-foot cantilever in order to accommodate any potential utility conflicts within, and possibly seaward of, Lagoon Road. The tied-back structural wall would be carved and colored to blend in with the geologic structure of the adjacent natural bluff.

2. Recognizing that as coastal erosion will continue to advance and erode the face of the coastal bluff and flank Option No. 1, we considered modifying Option No. 1, by embedding the face of the proposed tied-back wall 6+ feet back into the face of the coastal bluff to substantially increase the length of time into the future when this wall might eventually be flanked, necessitating extending the length of the wall both east and west of the currently proposed 50-foot wall alignment (see Figure 17).



3. A third option considers construction of a tied-back drilled pier wall. This alternative would be set back from the existing bluff face approximately 6 feet (see Figure 18). This distance includes the use of a 6-foot bench in front of the drilled pier wall. The drilled pier system would be installed sufficiently below the shoreline platform in order to provide fixity. The upper portion of the drilled pier would be exposed by cutting away the outer portion of the bluff within the terrace deposits, and constructing a cantilevered wall with tied-back anchors passing through the drilled piers in order to provide stability for the drilled pier wall system. The cantilevered wall would be carved and colored to match the terrace deposits. With the erosion rates stated above, we anticipate that the drilled pier system would eventually become exposed and, as such, a tied-back shotcrete wall may need to be installed as the piers become exposed to prevent loss of soil from behind the wall system. Drilled piers should be designed to have adequate embedment at an elevation below the top of shore platform, and any subsequent tied-back wall system should be designed to maintain bluff stability.

These structural alternatives are illustrated in Figures 16 through 18.

It is important to note that as part of any permitting process, an alternatives study of options that could be implemented to mitigate the emergency conditions would need to be performed. As such, as part of this work, we have performed an alternatives analysis of other possible bluff remediation measures. Included in this analysis are the three options discussed above.

7.2 Alternatives Analysis

The alternatives studied in our assessment include the use of structures to locally stabilize the portion of the bluff at risk, strengthening of bluff materials, buttressing a portion of the subject bluff, and isolating portions of the impacted area via underpinning, as well as a no project option.

The stability of the existing bluff is initially controlled by the strength of the terrace deposits, vehicular surcharge loads on Lagoon Road, and the geometry of the bluff itself. Over time, erosion will continue to advance landward and the proposed stabilization measures will grow both laterally and vertically. As such, when considering the viability of a given alternative, one needs to take into account the impact of this lateral and vertical growth of the impacted bluff.



Each alternative is discussed below in terms of their pros and cons. This analysis was used to select the preferred alternative.

7.2.1 Bluff Stabilization: Structural-Tied-Back Wall at Face of Existing Bluff

One method for mitigation of the top-of-bluff concerns is to construct a bluff stabilization structure consisting of a tieback-supported structural skin or wall placed on the existing face of the bluff. This alternative stabilizes the bluff by preventing further bluff erosion and increasing the stability of the upper-bluff materials, thereby mitigating top-of-bluff failures that would encroach significantly into Lagoon Road.

The structural skin would extend from the top of the bluff to the shore platform. To mitigate undermining, the structural skin would be embedded approximately 2 feet into the underlying shore platform. Due to underground utilities, the tieback anchors would likely start at a distance of approximately 15 feet below the top of the wall. The wall would be designed as a cantilevered system above the top row of anchors.

The primary drawback of this alternative is that the remediation measure is prone to flanking of the improvement, if the alternative is placed at the current bluff face and only covering that portion of the bluff that is considered immediately at risk. As such, this alternative would eventually need to be extended laterally beyond the area of the bluff required at this time in order to maintain bluff integrity. If flanking was allowed to continue, the remediated portion of the bluff face would eventually become compromised, resulting in the eventual failure of the tied-back wall.

7.2.2 Bluff Stabilization: Structural-Tied-Back Structural Wall Recessed Into Face of Existing Bluff

One way to mitigate the immediate potential for outflanking of the bluff stabilization structure would be to locate the structural tied-back skin/wall system approximately 6 feet from the face of the existing bluff face. This would be achieved by scaling the bluff face during construction of the structural skin/wall. The result would be a structural wall inset into the existing bluff face, which would then permit the adjacent bluff to continue to erode at its natural rate, thus providing additional time to address the long-term needs of Lagoon Road and Anacapa Hall. At rates of erosion of 14 to 40 cm per year, this 6-foot sacrificial zone provides upwards of 13 years of service before additional remedial efforts would be required.



7.2.3 Bluff Stabilization: Tied-Back Drilled Pier Wall

Given the preceding, a viable alternative might be to install a series of drilled piers on relatively close spacing, say 5 to 6 feet out from the edge of Lagoon Road, as the first phase of a multi-phased project. When any of the drilled piers become exposed in the future, similar to what currently exists at Isla Vista, the exposed piers would then be covered with a naturalized architectural surface to blend in with the adjacent coastal bluffs and, as necessary, tiebacks (similar to what is currently being proposed) could be installed, which would essentially result in the same project that is currently being proposed, albeit somewhat landward, with an ongoing requirement that, as new sections of drilled piers become exposed, those sections would also be structurally stabilized and naturalized with an architectural treatment, essentially resulting in the same visual appearance as that currently being proposed.

A variation of this alternative would be the immediate construction of a partial drilled pier wall extending from the bluff top possibly down to the geologic contact, creating a sacrificial bench that would facilitate construction and could then be relandscaped to minimize its visual appearance. With the erosion rates stated above, we anticipate that the drilled pier system would eventually become exposed and, as such, a continuation of this tied-back shotcrete wall would need to be constructed as the piers become exposed to prevent loss of soil from behind the wall system. Drilled piers should be designed to have adequate embedment at an elevation below the top of the shore platform.

7.2.4 Rock Riprap

Protective rock at the base of the bluff lowers the rate of erosion by dissipating wave energy and shielding the lower sea cliff from wave attack. A key factor that governs the size of the rock riprap necessary to mitigate bluff retreat is the height of the bluff needing protection. Protection of the base of the bluff will slow the rate of erosion. However, studies have shown that the top-of-bluff could still continue to erode due to the instability of the upper terrace materials. As such, for this location, the rock riprap would likely need to protect the full height of the bluff. This will result in a rock revetment needing to be constructed that will result in a significant footprint on an already small usable beach area. Our experience with the CCC has been that such rock structures are not typically permitted. As such, we summarily discount the viability of a rock riprap solution.



7.2.5 Chemical Grouting

The use of chemical permeation grouting can be a viable method for increasing the strength of in-situ soils by essentially cementing or gluing the soil grains together. This approach is generally applicable to soils having few fines and high permeabilities. This method has, at times, been confused with an alternative grouting method known as compaction grouting, which seeks to improve weak soils by densification and the inclusion of grout columns.

The concept of ground improvement along coastal bluffs works well in theory, assuming that the entire soil mass can be equally permeated with an extremely low viscosity chemical to essentially glue the soil mass together. The instability of the coastal bluff in this location is associated with both inadequate soil strength along a given hypothetical failure geometry, with the ongoing marine erosion creating a near-vertical face that continues to calve off, resulting in an only marginally stable coastal bluff that is retreating landward and now locally threatening critical campus infrastructure.

Cementitious grouts are not capable of achieving any degree of uniform soil-mass penetration, and although they are capable of increasing soil strengths, at least locally, they provide essentially no benefit in solidifying clean sands. Chemical grouts, however, can provide more effective permeation, increasing both cohesion and soil strength. The reality is that for chemical grouting to be effective in stabilizing coastal bluffs, one must essentially permeate the outer 20 to 30 feet of the slope face (or roughly half the slope height); a difficult, if not impossible, challenge. In addition, chemical grouts are injected under pressure and, when confined with adequate overburden, can effectively permeate relatively large areas. However, adjacent the face of a bluff, no effective confinement exists, and even controlled grouting can blow out portions of the bluff face if any excessive pressure buildup occurs.

A constructability challenge then exists, necessitating men and equipment on the face of the coastal bluff, with the requirement of injecting a chemical into dense and permeable formational soils in an attempt to develop homogenous penetration. The reality is that this becomes a very dangerous construction technique, with the risk of additional construction failures occurring during the grouting process, placing the construction crew and the public in great physical danger. More importantly, without solidifying the entire mass, those unsolidified zones will continue to erode, triggering yet additional coastal bluff failures.



7.2.6 Groundwater Controls, Irrigation Restrictions, and Drought-Tolerant Planting

Top-of-bluff erosion is oftentimes impacted by groundwater and irrigation, which result in seeps and springs that exit the bluff face and which lead to more rapid material wasting. As such, reduction of groundwater and limiting irrigation, as well as using drought-tolerant plants, can mitigate and reduce bluff erosion.

We unhesitatingly support the continued strict control of plantings and irrigation in sensitive areas of the site in order to control excess moisture from triggering failures of bluff-top sediments. It must be emphasized that excess irrigation water is not the cause of the current situation. The instability that we are addressing is the result of ongoing marine erosion of the lower sea cliff. While strict irrigation and runoff control is a valuable preventative strategy in general, nothing about the drainage configuration atop the coastal bluff contributes to the ongoing wave attack at the base of the bluff. Likewise, instituting stricter landscaping and irrigation controls at this time would not mitigate the marginally stable near-vertical coastal bluffs. These measures would not affect the current need for the proposed project.

7.2.7 Abandon Lagoon Road and Reroute Traffic Westerly of Anacapa Hall

While in concept, this is a laudable approach, based on our discussions with University Staff, Lagoon Road is a major arterial providing vehicular access through and around the campus, also accessing one of the larger parking lots, specifically Parking Lot #6. Closing Lagoon Road in front of Anacapa Hall and forcing traffic around Anacapa Hall places traffic along the more limited access interior streets. This is problematic, as there is significant student foot traffic across these streets, frankly with inadequate signage and lit pedestrian crosswalks. Lagoon Road also supports much of the major campus utilities as part of its perimeter loop system serving the entire campus. Rerouting those utilities would be a multi-million dollar effort, with increased disruption, both in terms of construction and, as importantly, future maintenance within more narrow interior streets that were never designed to accommodate these major utility loops.

7.2.8 Underpinning

One alternative that can be implemented when needed would be to underpin Anacapa Hall with a series of drilled shafts. This alternative protects the building from damage as the bluff encroaches near the building. However, this alternative does nothing to protect the vital Lagoon Road. Thus, underpinning as a standalone project without the benefit of a seawall



results in the progressive loss of the upper bluff, eventually exposing the drilled piers, with the end-result being similar to what exists along portions of Isla Vista.

Additionally, the safety of the beach-going public is not addressed by a standalone underpinning alternative. Again, the problems at Isla Vista are illustrative of the problems with standalone underpinning, creating a very real and present danger of personal injury as the result of a coastal bluff failure that underpinning cannot mitigate.

7.2.9 No Project

If the coastal bluff is left in its current condition, ongoing coastal bluff failures will ultimately lead to the loss of Lagoon Road and, as importantly, the existing infrastructure that is critical to the operation of the campus.

7.3 Preferred Alternative

We have provided limited discussion and general engineering recommendations for alternative wall systems in the following sections. We recommend that any alternative provide support to the weaker upper bluff terrace deposits, which largely influence the gross stability of the bluff.

8 GEOTECHNICAL RECOMMENDATIONS FOR PREFERRED ALTERNATIVE

8.1 General Earthwork

All earthwork should be performed in accordance the Standard Specifications for Public Works Construction (SSPWC), except where in conflict with University of California at Santa Barbara standards and specifications for work on their property. We recommend that all grading operations be observed, tested, and documented under the direction of a Registered Geotechnical Engineer or a Certified Engineering Geologist.



8.2 Tieback Design Loads

8.2.1 Remediated Bluff Preferred Option Stability Analysis-Static

We evaluated the remediated bluff assuming that the bluff is stabilized using Alternative Option No. 2. This option consists of constructing a tieback anchor-supported shotcrete structural skin on the existing bluff face over a longitudinal distance of 50 feet, as shown on Figure 17.

We evaluated the stability of the remediated slope in order to assess the number of anchors, the spacing of the anchors, and the anchor loads needed to raise the computed factor of safety of the 50-foot wall section above 1.5 for static loading.

The results of our analyses indicate that four rows of anchors having a design load of 128 kips and spaced 10 feet horizontally are needed to raise the stability of the slope to a minimum factor of safety of 1.5 for static conditions. The results of our analyses are presented in Appendix D.

8.2.2 Remediated Bluff Preferred Option Stability Analysis-Pseudo Static

In addition to raising the static factor of safety to greater than 1.5, the remediated slope needs to have a minimum factor of safety greater than 1.1 for pseudo-static conditions and for a horizontal seismic efficient of 1.2.

For the remediated slope described above, the results of our analyses indicate that for four rows of anchors having a design load of 128 kips and spaced 10 feet horizontally, the computed pseudo-static factor of safety is greater than 1.1. The results of our analyses are presented in Appendix D.

8.3 Tieback Requirements

Tiebacks should be designed to accommodate the loads calculated from the built-out stability analyses provided in Appendix D, resulting in design loads of 128 kips per tieback. The tieback unbonded zone for this design condition is 30 feet. Post-grouted tiebacks should be used for all lateral restraint. All tiebacks should consist of DYWIDAG Systems International



(DSI) anchors with Type C double-corrosion protection. DSI product literature is provided in Appendix E.

We recommend that all tiebacks be proof tested to 133 percent of the design load under the observation of a qualified engineer or engineer’s representative.

8.4 Wall Drainage

Adequate drainage must be provided behind any proposed retaining wall system. For tied-back walls, we recommend that J-Drain 302, a high-quality geocomposite drainboard, be used for all vertical chimney drains. All chimney drains should be manifolded into a horizontal wall drain to exit the wall face.

8.5 Reinforced Concrete

We recommend that a minimum 5,000 psi concrete be used for structural and architectural shotcrete applications to provide optimal strength and long-term abrasion resistance. Furthermore, epoxy-coated steel reinforcement should be incorporated to prevent corrosion in this aggressive marine environment.

9 GENERAL CONSTRUCTION METHOD FOR PREFERRED COASTAL BLUFF REMEDIATION

As described above, the preferred coastal bluff remediation consists of constructing a tieback anchor-supported structural skin. This alternative provides additional lateral loading that buttresses the bluff via the anchor-supported structural skin.

To construct this alternative, the following procedure will generally be followed:

1. Install BMPs to control construction materials and debris from leaving the site, as well as to protect adjacent areas from storm runoff from the construction site.

2. Clear and grub the face of the bluff.

3. Using either a crane-suspended construction basket or scaffolding founded into the shore platform, tieback anchors will be installed at specified locations. These anchors



will be drilled into the bluff face using pneumatic drills. The drill holes will be cased as needed, and will be on the order of 6 inches in diameter. Once the length of anchor has been drilled, pre-stressing steel reinforcing strands will be placed in the drilled hole and then grouted in place. The grout will likely be pumped from the top of top of bluff using concrete pump trucks. Grouting of anchors will be performed under pressure and anchors will be post-grouted.

4. Once anchors are installed, epoxy-coated steel reinforcing will be placed on the bluff face and tied into the bluff face to hold the reinforcing in place prior to the placement of the shotcrete structural skin.

5. The structural skin will be constructed by applying shotcrete from the bottom of the wall up.

6. Once shotcrete is set sufficiently, the anchors will be tested for capacity.

7. Once the shotcrete wall and anchors are installed, the outer face of the shotcrete will have a carved, sculptured, and colored surface placed over the shotcrete skin. This surface course will be colored and textured to match the conditions of the adjacent bluff face.

8. The construction site will be cleaned up and top-of-bluff vegetation will be reestablished.

The construction activities will require a staging area for storage and a stockpiling area for placement of construction materials and equipment. In addition, traffic control will need to be implemented along Lagoon Road in order to maintain safety for traffic. A portion of the top-of-bluff area will need to be secured in order to maintain safety. In addition, given likely restrictions to construction-related activities, we anticipate that materials and operations will require top-of-bluff work and work over the top of the bluff.

10 LIMITATIONS

Geotechnical engineering and the earth sciences are characterized by uncertainty. Professional judgments presented herein are based partly on our evaluation of the technical



information gathered, partly on our understanding of the proposed construction, and partly on our general experience. Our engineering work and judgments rendered meet the current professional standards. We do not guarantee the performance of the project in any respect.

We have investigated only a small portion of the pertinent soil, rock, and groundwater conditions of the subject site. The opinions and conclusions made herein were based on the assumption that those rock and soil conditions do not deviate appreciably from those encountered during our field investigation. We recommend that a soil engineer from our office observe construction to assist in identifying soil conditions that may be significantly different from assumed in our analyses. Additional recommendations may be required at that time.



REFERENCES

Barnard, Patrick L., D.L. Revell, D. Hoover, J. Warrick, J. Brocatus, A.E. Draut, P. Dartnell,

E. Elias, N. Mustain, P.E. Hart, and H.F. Ryan, 2009, Coastal Processes Study of Santa Barbara and Ventura Counties, California. Final Report to the Beach Erosion Authority for Clean Oceans and Nourishment (BEACON). USGS Open File Report 2009-1029.

California Department of Navigation and Ocean Development, July 1977, Assessment and Atlas of Shoreline Erosion along the California Coast.

Griggs, Gary, K. Patsch, and L. Savoy, 2005, Living With the Changing California Coast. University of California Press, Berkeley and Los Angeles, California.

California Department of Navigation and Ocean Development, 1977, Assessment and Atlas of Shoreline Erosion along the California Coast.

Fugro West, Inc., January 2006, Geotechnical Engineering Report – UCSB Report Number 336, Ocean Science Education Building, University of California, Santa Barbara, Santa Barbara, California.

Fugro West, Inc., January 2006, Geotechnical Engineering Report – UCSB Report Number 336, Ocean Science Education Building, University of California, Santa Barbara, Santa Barbara, California.

Fugro West, Inc., April 28, 2016, Geotechnical and Geological Consultation, Response to California Coastal Regarding 100-Year Bluff Setback, UCSB Infrastructure Renewal Phase 1C, University of California, California.

Fugro West, Inc., May 6, 2016, Geotechnical study Prepared in Response to Coastal Commission Comment, UCSD Infrastructure Renewal Phase University of California, Santa Barbara, California.

Fugro West, Inc., May 6, 2016, Geotechnical study Prepared in Response to Coastal Commission Comment, UCSD Infrastructure Renewal Phase University of California, Santa Barbara, California.

Fugro West, Inc., August 2016, Email to Teli Foster and Shan Hammond, Slope stability of coastal bluff at Lagoon Road.



REFERENCES

(continued)

Hapke, Cheryl J., D. Reid, and B. Richmond, May 2009, Rates and Trends of Coastal

Change in California and the Regional Behavior of the Beach and Cliff System, in Journal of Coastal Research, 25(3), pg. 603-615, West Palm Beach, FL, ISSN 0749-0208.

Hapke, Cheryl J., and D. Reid, 2007, National Assessment of Shoreline Change Part 4: Historical Coastal Cliff Retreat along the California Coast, USGS Open File Report 2007-1133.

Hapke, Cheryl J., D. Reid, B.M. Richmond, P. Ruggiero, and J. List, 2006, National Assessment of Shoreline Change Part 3: Historical Shoreline Change and Associated Coastal Land Loss along Sandy Shorelines of the California Coast, USGS Open File Report 2006-1219.

Minor, Scott A., K.S. Kellogg, R.G. Stanley, P. Stone, C.L. Powell II, L.D. Gurrola, A.J. Selting, and T.R. Brandt, 2003, Preliminary Geologic Map of the Santa Barbara Coastal Plain Area, Santa Barbara County, California, USGS Open File Report 02-136, Version 1.1.

von Thury, Eva. E, 2013, Using Laser Scanning Technology to Monitor Coastal Erosion and Sea-Cliff Retreat in Southern Santa Barbara County, California, Thesis, University of California Santa Barbara, June 2013.



TABLE 1

SUMMARY OF SELECTED FAULTS

AND THEIR CORRESPONDING

MAXIMUM GROUND MOTION CHARACTERISTICS

AT THE PROJECT SITE

FAULT

Approximate

Distance,

miles

Max

Earthquake

Magnitude

Estimated

Peak Ground

Acceleration,

g

Estimated

Modified

Mercalli

Site

Intensity

North Channel Slope 0.3 7.1 0.788 XI

M. Ridge-Arroyo Parida-

Santa Ana 1.2 6.7 0.613 X

Santa Ynez (West) 8.3 6.9 0.279 IX

Channel Island Thrust

(Eastern) 9.6 7.4 0.398 X

Red Mountain 10.6 6.8 0.271 IX

Montalivo-Oak Ridge

Trend 11.2 6.6 0.234 IX

Santa Ynez (East) 12.7 7.0 0.218 VIII

Ventura-Pitas Point 17.1 6.8 0.192 VIII

Los Alamos-West Baseline 18.8 6.8 0.179 VIII

Oak Ridge(Blind Thrust

Offshore) 18.9 6.9 0.188 VIII

Santa Cruz Island 24.4 6.8 0.146 VIII

Anacapa-Dume 26.7 7.3 0.178 VIII

Santo Rosa Island 27.0 6.9 0.143 VII

Lions Head 29.9 6.6 0.113 VII

Big Pine 30.6 6.7 0.096 VII

San Luis Range (South

Margin) 37.8 7 0.116 VII

Oak Ridge (Onshore) 38.0 6.9 0.110 VII

San Cayetano 38.5 6.8 0.103 VII

Simi-Santa Rosa 41.0 6.7 0.093 VII

Casmalia 41.3 6.5 0.083 VII

Pletio Thrust 43.4 7.2 0.116 VII

APPENDIX A

FUGRO WEST JANUARY 2006 REPORT

APPENDIX B

RESULTS OF EQFAULT SEARCH

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* *

* E Q F A U L T *

* *

* Version 3.00 *

* *

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DETERMINISTIC ESTIMATION OF

PEAK ACCELERATION FROM DIGITIZED FAULTS

JOB NUMBER: 9842-0000

DATE: 06-20-2017

JOB NAME: UCSB

CALCULATION NAME: Test Run Analysis

FAULT-DATA-FILE NAME: CDMGFLTE.DAT

SITE COORDINATES:

SITE LATITUDE: 34.4108

SITE LONGITUDE: 119.8423

SEARCH RADIUS: 100 mi

ATTENUATION RELATION: 3) Boore et al. (1997) Horiz. - NEHRP D (250)

UNCERTAINTY (M=Median, S=Sigma): M Number of Sigmas: 0.0

DISTANCE MEASURE: cd_2drp

SCOND: 0

Basement Depth: 5.00 km Campbell SSR: Campbell SHR:

COMPUTE PEAK HORIZONTAL ACCELERATION

FAULT-DATA FILE USED: CDMGFLTE.DAT

MINIMUM DEPTH VALUE (km): 0.0

---------------

EQFAULT SUMMARY

---------------

-----------------------------

DETERMINISTIC SITE PARAMETERS

-----------------------------

Page 1

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| |ESTIMATED MAX. EARTHQUAKE EVENT

| APPROXIMATE |-------------------------------

ABBREVIATED | DISTANCE | MAXIMUM | PEAK |EST. SITE

FAULT NAME | mi (km) |EARTHQUAKE| SITE |INTENSITY

| | MAG.(Mw) | ACCEL. g |MOD.MERC.

================================|==============|==========|==========|=========

NORTH CHANNEL SLOPE | 0.3( 0.5)| 7.1 | 0.788 | XI

M.RIDGE-ARROYO PARIDA-SANTA ANA | 1.2( 1.9)| 6.7 | 0.613 | X

SANTA YNEZ (West) | 8.3( 13.3)| 6.9 | 0.279 | IX

CHANNEL IS. THRUST (Eastern) | 9.6( 15.5)| 7.4 | 0.398 | X

RED MOUNTAIN | 10.6( 17.1)| 6.8 | 0.271 | IX

MONTALVO-OAK RIDGE TREND | 11.2( 18.1)| 6.6 | 0.234 | IX

SANTA YNEZ (East) | 12.7( 20.5)| 7.0 | 0.218 | VIII

VENTURA - PITAS POINT | 17.1( 27.5)| 6.8 | 0.192 | VIII

LOS ALAMOS-W. BASELINE | 18.8( 30.2)| 6.8 | 0.179 | VIII

OAK RIDGE(Blind Thrust Offshore)| 18.9( 30.4)| 6.9 | 0.188 | VIII

SANTA CRUZ ISLAND | 24.4( 39.3)| 6.8 | 0.146 | VIII

ANACAPA-DUME | 26.7( 42.9)| 7.3 | 0.178 | VIII

SANTA ROSA ISLAND | 27.0( 43.5)| 6.9 | 0.143 | VIII

LIONS HEAD | 29.9( 48.1)| 6.6 | 0.113 | VII

BIG PINE | 30.6( 49.2)| 6.7 | 0.096 | VII

SAN LUIS RANGE (S. Margin) | 37.8( 60.8)| 7.0 | 0.116 | VII

OAK RIDGE (Onshore) | 38.0( 61.2)| 6.9 | 0.110 | VII

SAN CAYETANO | 38.5( 61.9)| 6.8 | 0.103 | VII

SIMI-SANTA ROSA | 41.0( 66.0)| 6.7 | 0.093 | VII

CASMALIA (Orcutt Frontal Fault) | 41.3( 66.5)| 6.5 | 0.083 | VII

PLEITO THRUST | 43.4( 69.8)| 7.2 | 0.116 | VII

SAN ANDREAS - Carrizo | 44.2( 71.1)| 7.2 | 0.094 | VII

SAN ANDREAS - 1857 Rupture | 44.2( 71.1)| 7.8 | 0.129 | VIII

SAN JUAN | 51.3( 82.6)| 7.0 | 0.075 | VII

LOS OSOS | 56.3( 90.6)| 6.8 | 0.077 | VII

MALIBU COAST | 56.7( 91.2)| 6.7 | 0.073 | VII

HOSGRI | 57.6( 92.7)| 7.3 | 0.081 | VII

SAN GABRIEL | 58.9( 94.8)| 7.0 | 0.068 | VI

GARLOCK (West) | 60.1( 96.8)| 7.1 | 0.070 | VI

WHITE WOLF | 60.5( 97.3)| 7.2 | 0.09

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