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HomeMy WebLinkAbout2022_01_Waipio_Engineering_Evaluation_Report Preliminary Geotechnical Engineering Evaluation Waipi‘o Valley Road Prepared for January 2022 Job No. 3140023002 500 Ala Moana Boulevard, Suite 6-250 Honolulu, Hawai’i 96813 Tel 808.587.7747 Preliminary Geotechnical Engineering Evaluation Waipi‘o Valley Road Prepared for January 2022 Job No. 3140023002 Prepared by Mark J. Herrenkohl, LEG Daniel J. Trisler, PE Sr. Associate Engineering Geologist Principal Geotechnical Engineer 3140023002 January 2022 1. 1 2 3.0 2 3.1 Topographic and Geomorphic Features 2 3.2 Geologic and Soil Mapping 3 3.3 Subsurface Conditions 3 3.4 Groundwater Conditions 3 3.5 Geologic and Seismic Hazards 4 3.6 Road Transects and Sections 5 5 4.1 Rockfall Mechanism 5 4.2 FHWA Road Evaluation 6 4.3 Rockfall Computer Modeling 7 4.3.1 Rockfall Modeling Method 7 4.3.2 Rockfall Model Results and Discussion 9 4.4 Australian Geomechanics Society Risk Evaluation 10 13 5.1 Overhang in Upper Sections (F-W-01 to F-W-02) 13 5.2 Downhill Slope Evaluation (Downslope of Guardrails) 16 16 6.1 Rockfall Mitigation Methods 16 6.1.1 Excavation 17 6.1.2 Scaling 17 6.1.3 Localized Rockfall Stabilization 17 6.1.4 Rockfall Fence 18 6.1.5 Rockfall Netting 18 6.1.6 Hybrid Fencing Systems 18 6.1.7 Concrete Barriers 19 6.2 Comparison of Rockfall Mitigation Methods 19 6.2.1 Upper Section 20 6.2.2 Central and Lower Sections 20 6.3 Soil Slope Mitigation Options 20 ii | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 6.3.1 Upslope Soil Slope Mitigation 20 6.3.2 Downslope Soil Slope Mitigation 21 6.4 Retaining Walls 22 6.4.1 Gabion Wall 22 6.4.2 Mechanically Stabilized Earth (MSE) Wall 22 6.4.3 Cantilever Soldier Pile Wall with Lagging 23 6.5 Pavement Reconstruction 23 23 25 25 Table 1 – Groundwater Data from Nearby Wells 4 Table 2 – Rockfall Hazard Ratings Evaluation Summary 7 Table 3 – Site-Specific Parameters used in RocFall Model Trials 8 Table 4 – Trials Rockfall Model Results for Traverse WR-3 and WR-4, Waipi’o Valley Road 9 Table 5 – Risks of Death from Common Activities 10 Table 6 – Calculation of Rockfall Risk along Waipi‘o Valley Road 12 Table 7 – Rockfall Mitigation Methods Comparison 19 Figure 1 – Vicinity Map Figure 2 – Site Plan Figure 3 – WR-1 2019 Slide Traverse Figure 4 – WR-1 Profile, 2019 Waipi'o Slide Figure 5 – WR-3 and WR-4 Traverses, Rockfall Site Plan Figure 6 – WR-3 Profile, Waipi'o Rockfall Traverse Figure 7 – WR-4 Profile, Waipi'o Rockfall Traverse Figure 8 – Geohazards Sections and Areas Figure 9 – Digital Elevation Model (DEM) Slope Analysis Field Data Rockfall Evaluation Data Contents | iii 3140023002 January 2022 ADT average daily traffic AGS Australian Geomechanics Society AVR average vehicle risk bgs below ground surface County County of Hawai‘i cy cubic yard EOP edge of roadway pavement FHWA Federal Highway Administration ft/sec feet per second GPS Global Positioning System Hart Crowser Hart Crowser, a division of Haley & Aldrich HDOD Hawai‘i Department of Defense HDOT Hawai‘i Department of Transportation kJ kilo Joules km/hr kilometers per hour lb/sec pounds per second LiDAR light detection and ranging MSE Mechanically Stabilized Earth MSL mean sea level NRCS Natural Resource Conservation Service pcf pounds per cubic foot RHRS rockfall hazard rating system ROM relative order of magnitude State Route 19 Highway USGS United States Geological Society 3140023002 January 2022 Preliminary Geotechnical Engineering Evaluation Waipi‘o Valley Road 1.0 Hart Crowser, a division of Haley & Aldrich (Hart Crowser), is pleased to submit our preliminary geotechnical engineering evaluation for Waipi‘o Valley Road located in Waipi‘o Valley on the island of Hawai‘i (Figure 1). Our work was conducted for the County of Hawai‘i, Department of Public Works (County) in general accordance with Contract Number C.008227 dated April 2, 2020. Waipi‘o Valley Road is approximately 4,100 feet or 0.8 miles long, from the Waipi‘o Valley Road Lookout to the Waipi‘o Valley floor at the 4-wheel drive beach-bound hairpin turn. The road is situated on the south valley wall near the mouth of the valley. A history of geologic slope hazards and related roadway instability and vehicle safety issues prompted the County to request an assessment of the rockfall risk to Waipi‘o Valley Road and evaluate potential options to mitigate risk for the County’s consideration. In support of this preliminary geotechnical engineering evaluation, Hart Crowser conducted the following tasks: Performed a background data review of available geologic and soils mapping data, topographic information, and County-provided maintenance and vehicle/pedestrian road-use information; Conducted a field reconnaissance of the road including collecting data for evaluating rockfall hazards and roadway instability conditions; Performed rappelling traverses and surface reconnaissance to directly assess site conditions and collect data for further rockfall and geotechnical engineering evaluation; Evaluated the collected data for rockfall hazards and roadway instability using the Federal Highway Administration’s (FHWA) Rockfall Hazard Rating System (RHRS), RocFall software program by RocScience©, and SLIDE2 Modeler™ modeling; Summarized the hazard of falling rocks and risks to persons and vehicles using methodology of the Australian Geomechanics Society; Considered methods for mitigating risks to the roadway and associated relative costs; and Compiled this report with our findings, evaluations, conclusions and recommendations. A summary of our site work and our preliminary engineering evaluation are presented in the following sections of this report. Referenced figures are presented after the report text followed by ancillary appendices. 2 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 2.0 Waipi‘o Valley Road is located on the northern Waipi‘o. The roadway is narrow and winds down along the steep hillside of the south valley wall, losing approximately 800 feet elevation in 0.7 miles. The geomorphology of this part of the island can create significant runoff and storm stages in the streams following rainfall events. Based on information from the County, we understand that a slope failure occurred in March 2019, following heavy rainfall and extremely high stream flows associated with Hurricane Lane. The landslide occurred below Waipi‘o Valley Road, approximately 0.3 miles from the Waipi‘o Road Lookout and Park (Figure 2). Hart Crowser conducted an initial site reconnaissance with County staff on April 29, 2020 followed by a detailed field reconnaissance of the roadway on June 1-2, 2020. From August 27 through September 4, Hart Crowser field personnel performed on-rope rappels of the slopes above and below Waipi‘o Valley Road to further assess rockfall and slide hazards. Based on our observations, there is one primary slide location, referred to as the March 2019 primary slide described in this report. The primary slide is approximately 500 feet tall and 70 feet wide and extends from the downslope road edge towards the Wailoa Stream valley below (refer to Figure 3). We also observed minor rockfalls along the road edge and numerous line-of-sight hazards for vehicles and pedestrians traveling on the lower portion of the roadway. A photograph log of our field observations is provided in Appendix A-1. 3.0 Our understanding of site conditions is based on regional geologic and topographic maps, light detection and ranging (LiDAR) data, field reconnaissance work, and our slope rappel traverses above and below Waipi‘o Valley Road. Vertical elevations presented in this report are based on field global positioning system (GPS) measurements and available LiDAR data, and not intended for production engineering design. Collected GPS field data points and features of the road are shown on Figure 2. 3.1 in the on the northeastern flank of Kohala, is an amphitheater- submarine landslide, whose head scarp corresponds with the present-day Kohala sea cliff that extends the head scarp as waterfalls, and knickpoints propagated upstream through erosion and resulting undercutting at each waterfalls’ vertical plunge pool (Lamb et al. 2007). level (MSL) to coastal elevations of roughly 1,000 feet MSL. With slopes of approximately 70 to 100 percent, the valley extends inland to the southwest, then makes a sudden turn to the northwest where NRCS 2018). In the valley, several tributary streams flow to form Wailoa Stream, which in turn flows into the sea. The valley floor is nearly flat as a result of alluvial fill deposited during recent sea stands above present sea level (Macdonald and Abbot 1970). This is especially so at the mouth of the valley, which is now mostly wetlands (Fletcher et al. 2002). Waipi‘o Valley Road Preliminary Evaluation | 3 3140023002 January 2022 Vegetation varies in the upland areas from evergreen forest land to shrub and brush rangeland. In the lowland and valley areas, land coverage varies from forested to non-forested wetlands, as well as cropland and pasture. 3.2 Geologic Regional site geology is provided in Geologic Map of the State of Hawai‘i, Sheet 8—Island of Hawai’i (Sherrod et al. 2007). Most of the site has been described volcanics lava flows (Qpl) consisting of tholeiitic basalt in the older layers and transitional and alkalic basalt in the younger layers, primarily occupying the upper valley walls and the surrounding uplands (Wolfe and Morris 1996). Secondary surficial deposits include Holocene landslide deposits (Qls) consisting of blocks of lava flows mixed with soil and Holocene, and Pleistocene alluvium (Qa) consisting of unconsolidated deposits of gravel, sand, and silt (Sherrod et al. 2007). Where previously mapped, Qls deposits occupy the boundary at the lower slopes and the valley floor, while Qa deposits occupy the remaining valley floor. Surficial soils in the site area are described in the Natural Resources Conservation Service (NRCS) Web-based soil survey as “Kahena-Niulii-Rock outcrop complex” consisting of 70 to 100 percent slopes (NRCS 2006). The “Kahena-Niulii-Rock outcrop complex” varies from medial to hydrous silty clay loam to very cobbly hydrous silty clay loam down to basalt bedrock at approximately 37 to 47 inches below ground surface (bgs). This soil type has a low to moderately low hydraulic conductivity (approximately 0.00 to 0.06 inches/hour) with high runoff potential. This complex is described as foot slope, backslope, shoulder, and summit within land elevations of 2,000 to 3,600 feet derived from P hoehoe lava flows and volcanic ash. 3.3 Our interpretation of subsurface conditions at the site is based on the regional geologic mapping described above and our field observations in support of this project. We did not conduct subsurface borings at this site and, therefore, subsurface conditions would need to be better defined for design purposes. From this information, we interpret the site subsurface stratigraphy to generally consist of weathered basalt (saprolite) overlying basalt, as described below. A site plan and slope cross-sections are provided in Figures 2 and 4 through 7. Weathered Basalt (Saprolite). Extremely weathered to highly weathered basalt layers decomposing to soil with residual rock textures and some lesser weathered layers with few core stones within the residual soil mass. Basalt (‘A‘a & P hoehoe). The basalt varied from extremely weathered to slightly weathered ‘A‘a and P hoehoe layers, with the massive ‘A‘a core rock generally observed to be less weathered and the P hoehoe rock generally observed to be more weathered at the site. 3.4 No groundwater wells were installed as part of this study. Review of available groundwater data for a U.S. Geological Survey (USGS) well located at the top of Waipi‘o Valley, indicates a groundwater level of 2,786 feet MSL (Table 1) (USGS 2020). This water level is likely associated with local shallow perched 4 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 groundwater at the well site. Based on this information, perched groundwater could be encountered at various depths below Waipi‘o Valley Road. 1 – 3.5 Geologic Landslide and rockfall hazards for the State of Hawai‘i are described in the 2013 Update of the Multi-Hazard Mitigation Plan (HDOD 2013). Three main categories of land failure are listed as landslides, debris flows, and rockfalls, which can be distinguished by the initiating phenomena. The initiation point of the various failures are typically along bedding planes or materials that often form weak strata, such as loose or weekly bonded sands, clays, or volcanic ash. Strata of jointed or blocky rock, especially when over a layer of weak strata, are also common points of origin for land failures (Jellinger 1977). Weak strata can also be undermined or lose strength when exposed to natural forces such as rainfall or earthquakes. Two natural forces that have been identified by the state as significant factors in land failures are high intensity rainfall and seismicity. Hawai‘i Island is both a volcanically and seismically active region where landslide events are often triggered by earthquakes. From his doctoral dissertation, Namekar (2013) developed earthquake-induced landslide hazard maps for the Island of Hawai’i. Using empirical and analytical models in conjunction with data of historical earthquake-induced slide locations, the hazard maps show high hazard ratings in several areas of North weathered rock, and high rainfall conditions. The study also noted the correlation of rock slope failures that were influenced by the presence of pyroclastic materials. These pyroclastic materials can act as the weak strata described above. A report on the 2006 Bay earthquake offers a mapped distribution of the rockfalls and landslides in the area of the Kohala valleys, which was used in a comparative analysis with a high-resolution ground motion simulation model (Harp et al. 2014). In a three-dimensional finite-element analysis, earthquake shaking was modeled to reproduce the distribution of rockfalls and landslides following the 2006 K holo Bay earthquake and identify the leading factors producing the resultant distribution. The report notes the complex distribution of landslides, particularly the preferential locations along east-facing slopes, yet no landslides were reported to have occurred along Waipi‘o Valley Road. In a separate 2007 report, a sole rockfall was identified by reconnaissance on Waipi’o Valley Road which may have been attributed to the 2006 K holo Bay earthquake (Medley 2007). Waipi‘o Valley Road Preliminary Evaluation | 5 3140023002 January 2022 3.6 From our field observations, the length of the road can be divided into three separate sections considering differences in geology, potential roadside and upslope rockfall, and line-of-sight concerns; an Upper Section, Central Section, and Lower Section as shown in Figure 8 and described further in Appendix A-2. The Upper Section, which includes road transects F-W-01 and -02, is approximately 625 linear feet long, 17 to 19 feet wide, and consists of a hairpin turn in the road and line-of-sight concerns for uphill traveling vehicles and pedestrians. It also has a significant overhang of weathered basalt and residual soil anchored by tree roots along a portion of the slope crest that provide concerns of slope failure and rockfall. The Central Section, which includes road transects F-W-03 and -04, is approximately 1,570 linear feet long, 16 to 29 feet wide, relatively straight, crowded in places by the cliff on the upslope side, with a moderate to severe drop-off on the downslope side of the road. The 70-foot-wide surficial slide feature along the downslope side of the road reportedly occurred in March 2019. The Central Section has some localized risk of rockfall from upslope rock outcrops and boulders. The Lower Section, which includes road transects F-W-05 thru F-W-11, encompasses approximately 2,000 linear feet of road that narrows with many curves and line-of-sight concerns in both directions. The road width ranges from 11 to 20 feet. This road section also has potential risk of rockfall from roadside basalt outcrops and boulders from the upslope cliff. Above the crest and upslope of all three road sections is primarily vegetated with strawberry guava and eucalyptus. 4.0 We evaluated the occurrence of individual rockfall within the project area using two different methods. First, we considered the FHWA’s rockfall hazard rating system (FHWA 1993). This system assigns a relative rockfall hazard rating based on 10 measurable or observable field parameters. It is useful in evaluating the hazard of rockfall from one area compared to others. Where rockfall hazard was present, we conducted numerical modeling of rockfall delivery to the roadway using the RocFall software program by RocScience©. This program calculates the trajectory of rocks falling to the roadway, providing the travel distance, bounce height, and energy of those rocks for use in designing mitigation measures, such as rockfall fences. We further evaluated the numerical risk of rockfall using a methodology developed by the Australian Geomechanics Society (AGS 2000). This system calculates the probability of damage or injury from rockfall in a manner that can be compared with societal risk from other hazardous activities or occurrences. 4.1 We first considered the potential mechanisms of rock failure at the site from observations made during our field reconnaissance (Appendix A-2) and rappel traverse work (Appendix A-3). We evaluated the potential for individual rocks, rock wedge, planar sliding, and toppling failures within the project area based on joint orientations and characteristics. No kinematic analysis was performed. The 30- to 40-foot high slope observed upslope of the upper road (950 to 825 feet elevation), includes the Upper Section as previously identified, is characterized as saprolite basalt with moderate to severe fracturing (discontinuous 6 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 and random), with clay infilling in many locations. With decreasing elevation (Central to Lower Sections), the upslope roadside slope ranged in height from 20 to 30 feet and is characterized as jointed basalt with clinker zones and basalt outcrops with some infilling and residual boulders. We observed less weathering and fracturing of the basalt in the Lower Section of the road (i.e., below 400 feet MSL) (Figure 2). We accessed the slope area above the road from private property. Two representative vertical transects (WR-3 and WR-4) were traversed with ropes from approximately 1,000 feet MSL to Waipi‘o Valley Road (270 to 330 feet MSL) to map the slope geology and potential source(s) of rockfall (Figures 5 through 7). Along each traverse, transect points were documented for slope and geologic features and vegetation type, height, spacing, and diameter (Appendix A-3). For traverse WR-3, weathered basalt outcrops and subangular boulders were observed from approximately 635 to 575 feet MSL with variable jointing and some infilling. Weathered massive basalt outcrops were also observed along traverse WR-4 from approximately 500 to 390 feet MSL. Both observed outcrop areas are potential rockfall sources to areas below, including portions of Waipi‘o Valley Road. Our field observations indicate that the discontinuous and random jointing patterns in the basalt with significant infilling and weathering are relatively unstable and likely would generate localized slope failures immediately above Waipi‘o Valley Road. These upslope slope failures are more likely to occur with significant rain events and seismic activity. We observed individual boulders and small shallow soil/colluvial failures along portions of the roadside including some impact marks in the pavement from previous rockfall events. The basalt outcrops located at higher elevations (from 390 to 635 feet MSL) above the road are also potential sources of rockfall, though the density of vegetation in these areas may be a prohibiting factor in travel distance. 4.2 luation The FHWA uses a quantitative assessment of rockfall hazard to roadways, the “Rockfall Hazard Rating System,” or RHRS (FHWA 1993). This publication evaluates 10 parameters related to rockfall occurrence and exposure that are typical of roadways. The system is not intended to be a definitive calculation of risk to the public, but to provide a relative ranking for roadway sites. We evaluated the project site using this methodology and the FHWA guidance document. We considered each road section (Upper, Central, Lower) separately due to differences in geologic features and line-of-sight inferences as described previously. Our scoring methodology followed the criteria noted in Appendix A-2. One criterion, average vehicle risk (AVR), was based on average daily traffic (ADT) from the 2019 annual average daily traffic data (vehicles and pedestrians) documented by the County Department of Parks and Recreation at the Waipi‘o Valley Road Lookout. Table 2 below lists each parameter and the highest value we assigned for each parameter on each section of road. The sum of the criteria is the total value of each road section and is used for comparison purposes as described below. Detailed summary data and score tables for each of the 11 separate transects divided into road sections are provided in Appendix A-2. Waipi‘o Valley Road Preliminary Evaluation | 7 3140023002 January 2022 2 – RHRS Category Rating Criteria Description Highest Score Upper (F-W-01 to F-W-02) Central (F-W-03 to F-W-04) Lower (F-W-05 to F-W-11) Slope Height (upslope) Heights range from 18 to 41 feet 9 9 9 Ditch Effectiveness No catchment 81 81 81 Average Vehicle Risk AVR ranged from 4 to 24 percent (<25% of the time) 3 3 3 Decision Sight Distance Sight distance ranged from 27 to 64 percent (limited site distance most of lower road) 81 27 81 Roadway Width Width range from 11 to 29 feet 81 81 81 Case I – Differential Erosion Features Discontinuous/random, undulating to clay infilling 81 81 81 Or (highest value between Case 1 or 2) Case 2 – Difference in Erosion Rates Occasional differential erosion features, small to moderate difference erosion 9 9 9 Block Size or Quantity of Rockfall 0.3- to 2.0-foot block size, up to 1.0 cy 3 9 9 Climate High precipitation 27 27 27 History Occasional falls (assume 6 or more per year) 9 9 9 Total – (highest score for each category) 375 327 381 Note: The RHRS ratings were derived from our road reconnaissance observations only and don’t include observations and rockfall data collected from traverses of the upper slope areas. Based on the above assessment, the Waipi‘o Valley Road rockfall area would receive a score of between 327 and 381 by road section. Without comparative sites, these values do not provide much information. However, in support of SSFM International, Inc. for the Hawaii Department of Transportation (HDOT), Hart Crowser recently conducted rockfall hazard rating assessments along the Highway (State Route 19) in Hawaii County (Hart Crowser 2019). In that study, Hart Crowser assessed 21 upslope sites along 50 miles of the highway and calculated hazard ratings ranging from 81 to 351. Of the 21 upslope sites evaluated during the HDOT study, rockfall mitigation such as drapery netting or retaining walls was recommended for six of the sites. The hazard rating scores for Waipi‘o Valley Road are higher than the rating scores for the HDOT study. 4.3 Computer g 4.3.1 Rockfall Modeling Method Data from our field reconnaissance and rappel investigation along two traverses (WR-3 and WR-4) were used to support rockfall trajectory modeling for Waipi‘o Valley Road (Figures 5 through 7). Rockfall trajectory modeling addresses discrete rock block failures and is performed using the RocFall software 8 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 program by RocScience©. The program allows the user to input detailed cross sections of the slopes, assign material properties to the slope surfaces based on what was observed in the field (including vegetation and tree density), input the weight of the rocks based on observed average size and unit weight, and choose the geometry of the rock blocks (i.e., spherical or tabular, rounded or angular). Initial model trial results are compared to evidence of rockfall observed in the field to ground truth the model inputs, which are then adjusted as needed for the site. The parameters used in the model “trials” for each traverse are given in Table 3 below. – - Parameter Field Observations Selected Values Rock Shape Weathered basalt outcrops and boulders. Rounded hexagon and rhombus Rock Diameter Typical block size estimated to be 3 feet x 3 feet x 1 feet based on photographs and joint spacing measured in outcrops. 3 feet x 3 feet x 1 feet Rock Density No measured values. Average value for basalt selected based on published data. 170 pounds per cubic foot (pcf) Dynamic Friction Coefficient Based on the estimated friction angle of surfaces (= tangent of friction angle), estimated friction angle varies from 32 to 35 degrees 0.62 to 0.7 Rolling Friction Coefficient Varies based on material type, estimated based on published values (in general, harder materials have lower rolling friction coefficients). 0.5 to 0.75 Normal Coefficient of Restitution Basalt outcrop (0.35), Outcrops with soil and vegetation (0.33), Soil with vegetation, boulders, and outcrops (0.33), Soil with vegetation (0.3), Asphalt roadway (0.4) 0.3 to 0.4 Tangential Coefficient of Restitution Basalt outcrop (0.8), Outcrops with soil and vegetation (0.78), Soil with vegetation, boulders, and outcrops (0.78), Soil with vegetation (0.7), Asphalt roadway (0.9) 0.7 to 0.9 Forest/Vegetation Damping Vegetation type, height and spacing estimated in the field. Average height varies from 10 feet to 20 feet. Tree density with 5 to 15-feet spacing estimated to be “medium” with forest drag coefficient = 1100 pounds per second (lb/sec) and tree density with spacing greater than 15 feet estimated to be “open” with forest drag coefficient = 550 lb/sec. Height: 10 to 20 feet Forest drag coefficient: 550 to 1100 lb/sec Note: Average values for Normal and Tangential Coefficient taken from Pfeiffer, T.J., and Bowen, T.D., "Computer Simulation of Rockfalls." Bulletin of Association of Engineering Geologists. Vol. 26, No. 1. 1989, pp 135-146. For each model trial, 1,000 rock blocks are “thrown” from the upper slope of each traverse using a Monte Carlo simulation emanating from select seeder locations that are based on rock block clusters and rock outcrops observed during the field investigation. A data collector is placed at the bottom of the slope at the edge of roadway pavement (EOP), and after running the models, the number, bounce height, and kinetic energy of rock blocks reaching the roadway is recorded by the data collector. Waipi‘o Valley Road Preliminary Evaluation | 9 3140023002 January 2022 Two models were created for each traverse: one assuming static conditions of the rock slope (loose rock blocks falling without an impetus or initial velocity); and one that accounts for an impetus to rock motion (like a significant rainfall event, debris flow, earthquake, etc.) by applying an initial horizontal velocity to the rock blocks. Other parameters in each model run for the site (i.e., slope geometry, material, and rock properties, etc.) are the same. 4.3.2 Rockfall Model Results and Discussion Table 4 below summarizes the results of our analyses for the two Waipi’o Valley Road traverses. Detailed model outputs are provided in Appendix B. – -3 and WR- Road Location Traverse Initial Velocity Settings Rock Blocks that Cross the Data Collector Total Number of Rock Blocks Analyzed Retention (percent) Maximum Bounce Height (feet) Maximum Translational Kinetic Energy (kJ) Waipi'o Valley Road WR-3 Static: 0 ft/sec 343 967 64.5% 12.6 37 With impetus: 10 ft/sec 517 989 47.7% 17.6 65 WR-4 Static: 0 ft/sec 44 899 95.1% 25.9 16 With impetus: 10 ft/sec 135 972 86.1% 25.9 16 Note: Less than 1,000 rocks were analyzed during the model trials due to excess computing time or complicated rock block interaction/collisions. Outputs from the RocFall model trials, annotated with photographs collected during the field investigation, are included in Appendix B. For the two traverses modeled, maximum bounce heights at the edge of the roadway range from approximately 13 to 26 feet without an impetus and from approximately 18 to 26 feet with an impetus to rock motion. Maximum translational kinetic energies range from 16 to 37 kilojoules (kJ) without an impetus and from 16 to 65 kJ with an impetus to rock motion. Rockfall retention is a percentage of rock blocks in the model trials that do not enter the roadway. Many of the rock blocks in the model trials stopped falling or rolling in upslope locations due to low slope angles along portions of the traverses, or due to thick vegetation/tree density. Typical rockfall mitigation designs are based on the goal of 95 percent retention as defined by FHWA guidelines, which were developed for rockfall mitigation projects adjacent to federal highways. This means that 95 percent of potential rockfall must be contained within a properly designed catchment ditch or otherwise prevented from impacting the 10 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 roadway surface using rockfall stabilization or protection measures (i.e., rockfall barrier fencing, anchored or draped systems, shotcrete, etc.). The WR-4 traverse model in static conditions achieved the greater than 95 percent goal, whereas the other model results for WR-4 with impetus and both static and impetus conditions for WR-3 indicate less than 95 percent retention (bold in Table 4). Therefore, rockfall events occurring along the upper slopes adjacent to Waipi’o Valley Road are likely to impact the roadway. The bounce heights and energies of the rockfall events modeled could cause vehicular crashes and injuries or fatalities. During subsequent phases of the project, additional rockfall trajectory models can be evaluated iteratively with adjusted configuration of and/or modifications to the slopes and catchment ditches until the 95 percent retention goal is reached, if possible. 4.4 Based on the FHWA evaluation, our rockfall modeling using the RocFall software program by RocScience©, and historic rockfall occurrence, rockfall hazard is present on Waipi‘o Valley Road throughout the project site. However, these methods do not quantify the risk relative to other common exposures or relative to “acceptable” levels of risk. To estimate risk, an analysis must be used that evaluates both the probability of the occurrence of a rockfall event, as well as the consequence from the event. This probability can then be compared to standard acceptable risk levels. The AGS risk evaluation methodology (referred to for the remainder of this report as AGS methodology) provides this evaluation (AGS 2000, 2007). Although the AGS methodology is not specifically adopted in the United States or Hawai‘i, it provides a useful framework within which to evaluate potential risk. According to the AGS methodology, a suggested tolerable risk for loss of life1 for existing conditions varies between 10-4 (1:10,000), the lower threshold or persons most at risk, and 10-5 (1:100,000), the upper threshold or average of persons at risk, depending on the vulnerability of those at risk. For example, persons that would be trapped by collapse of a structure or buried by a rapidly moving landslide would be considered more vulnerable, while those that would have a reasonable chance to escape the risk would be considered less vulnerable. To put these values into perspective with common risks in society, the AGS (2007) provides risks for common human activities, shown in Table 5, below. As can be seen by these statistics, the tolerable risk recommended by the AGS methodology varies between that for motor vehicle use to perishing in a fire. 5 – Activity/Event Leading to Death Risk (Deaths per Participant per Year) Motorcycling, horse riding, ultra-light flying 1:1,000 to 1:10,000 (Canada) Motor vehicle use 1:23,000 Fall 1:30,000 Drowning 1:70,000 Fire/Burn 1:180,000 Choking on food 1:660,000 Scheduled airlines 1:1,000,000 (Canada) 1 Acceptable risks are usually considered to be one order of magnitude smaller than the above tolerable risks. Waipi‘o Valley Road Preliminary Evaluation | 11 3140023002 January 2022 Activity/Event Leading to Death Risk (Deaths per Participant per Year) Lightning strikes 1:32,000,000 Note: Data from Australia New South Wales for the years 1998 to 2002 and other sources. We used the AGS methodology to evaluate rockfall risk at the project site. The methodology computes the risk of death of an individual (RDI) with four parameters: Ph – the annual probability that rockfall will occur, PS:H – the probability that a rock will impact a specific section of the roadway, PT:S – the probability a car or pedestrian is present on the road when impacted, and VD:T – probability of loss of life if struck by the rock. Our estimation/determination of these parameters is described below. The parameter Ph is the number of rocks that fall per year. Data has not been collected at the site; however, transient road users reported that rockfall occurs frequently. The County reported at least three rock falls occur per year that require some action by the County. Anecdotal information we received suggests rockfall may occur every time a large storm hits the region. Therefore, we estimated that rockfall occurs about once every other month, resulting in an annual occurrence of six. We used this same frequency for the entire road length. Parameter PS;H is the probability of a vehicle or pedestrian occupying the portion of the road onto which rock falls. For a moving vehicle or pedestrian in the impact zone, the spatial probability of impact is calculated using the following equation (AGS 2000, Appendix E). (:)=24 1000 NV = Numbers of vehicles/pedestrians per day, L = Length of vehicle/pedestrian (meters), and VV = Velocity of (vehicle/pedestrian)/hour (km/hour). The County provided traffic information for vehicles and pedestrian use on Waipi‘o Valley Road. For 2019, the average trips per day in and out of Waipio Valley was reported at 174 vehicles and 137 pedestrians (total 311 trips per day). The average length of a mid-size 4-wheel drive sedan was estimated at approximately 15 feet (4.8 meters) and the velocity of the moving vehicle was estimated at approximately 10 mph (16 km/hr). Pedestrian traffic was also significant most days due to tourism. The average width of a person was estimated to be 1.5 feet (0.46 meter), with an average walking speed of 1.0 mph (1.60 km/hr), recognizing a person will travel faster into but much slower out of the valley. Using these values, the spatial probability of impact is estimated at approximately 2.2 x10-3 for a vehicle and 1.6 x10-3 for a pedestrian travelling on Waipi‘o Valley Road. Parameter PT:S is the temporal probability that a car or pedestrian is present on the roadway when the rock impacts it. The temporal probability is calculated using the following equation (Bunce, Cruden, and Morgenstern 1997), where t is the amount of time in the impact zone. 12 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 PT:S = t/8760 Based on the 4,100-foot length of roadway of concern and the average 15-foot car traveling 10 mph, we estimated that a car takes approximately 280 seconds (4.7 minutes) to traverse the roadway (this doesn’t include time for vehicles to stop for oncoming traffic). We multiplied that by 174 trips per day, which places cars on the road for 812 minutes (13.5 hours) per day. We divided that by the number of hours in a year (8,760 hours), resulting in a value of 1.5 x10-3. We estimated that a person takes approximately 45 minutes to traverse the roadway [average between traveling down (30 minutes) and up (60 minutes) the road]. We multiplied that by 137 trips per day, which places people on the road for approximately 6,200 minutes (approximately 100-man hours) per day. We assumed pedestrians are on the road in groups of two, for a total of 50-man hours. This resulted in a PT:S value of 5.7 x10-3. VD:T is the probability that someone would be killed should a rock impact their vehicle or them. We estimated this probability at 30 percent (0.3) for a vehicle and 100 percent (1.0) for a pedestrian. Although we believe these values are reasonable, they are largely subjective. Using these parameters in the AGS methodology, we determined the risk to loss of life for pedestrians and vehicular traffic, separately. The values we used, and the results are shown in Table 6. 6 – g Waipi‘o Valley Road Section Ph PS:H PT:S VD:T Probability (RDI) Pedestrian 6 1.6 x10-3 5.7 x10-3 1.0 5.5E-05 1:18,000 Vehicle 6 2.2 x10-3 1.5 x10-3 0.3 5.9E-06 1:170,000 For loss of life, the individual probability can be calculated from: Probability (RDI) = Ph x PS:H x PT:S x VD:T Based on these results, the estimated risk of loss of life ranges from greater than 1 in 18,000 for pedestrian access to 1 in 170,000 for vehicle access. The AGS methodology suggests that risks of less than 1 in 10,000 (lower threshold) to 1 in 100,000 (upper threshold) are acceptable for existing slopes, depending on a variety of factors. These results indicate that the risk to pedestrians in the project area is between the two risk thresholds and mitigation would be recommended to achieve acceptable risk over tolerable risk. This finding generally corroborates our observations of the locations of recent rockfall on the road and road shoulder of Waipi‘o Valley Road, as well as the known history of several rockfalls per year along this road. We note that these results rely on the estimated parameters described in the paragraphs above and, in particular, the values for rockfall occurrence per year. Given the results and the uncertainty of some of the parameters used, it is our opinion that mitigation is warranted to reduce the level of risk. Based on the RHRS scoring and rockfall modeling results, and the corresponding risk exceeds the recommended acceptable threshold in the AGS methodology, we evaluated mitigation options as noted in the following sections of this report. Waipi‘o Valley Road Preliminary Evaluation | 13 3140023002 January 2022 5.0 The soil conditions upslope and downslope of the road were assessed to determine what, if any, possible mitigation may be necessary to repair and stabilize Waipi‘o Valley Road. 5.1 ang in -W--W-02) The Upper Section of the road (transects F-W-01 and F-W-02) is the beginning of the downhill descent to the valley (Figures 2 and 8). Steep exposed residual soil slopes on the upslope side of the road have been susceptible to instability as indicated by past failures, the most recent of which were landslides in April 2018 and February 2019. In April 2018, overhanging trees and soil were reportedly deposited into the road after heavy rains (refer to Photo 1 below), causing several days of road closure for cleanup. In February 2019, the road was reportedly closed again after another upslope landslide blocked the traveled way. We do not have definitive limits and dimensions of where these past failures have occurred, so a general area is outlined in Figure 9. The instability is due to factors such as the slope steepness, exposure to water and wind, erodibility of the soil, and the proximity of top-heavy vegetation to the slope edge. These conditions have not been addressed to date by the County and it is likely that future instabilities will occur along this portion of Waipi‘o Valley Road. The top of the adjacent upslope slope cut is vegetated with ferns, plants, trees, and bushes (Photo 2). The slope is considered nearly vertical in places along the road. Some areas of the slope face are vegetated, but much of the slope face is either partially- or fully-exposed residual soil from transects F-W-01 to F-W-02 (Photos 3 and 4). During our June 2020 reconnaissance work, water seepage was noted in areas of the upslope face of transect F-W-01 along with approximately one cubic yard (cy) of soil debris possibly washed out/eroded from the uphill area onto the roadside. The road width in this transect is approximately 19 feet and the slope height is 17 feet (observed from the road). Along transect F-W-02, soil has eroded underneath the vegetation closest to the uphill area edge, thus resulting in overhangs. These overhangs are primarily held together by the root systems of the flora (Photo 4). The road width in this transect is approximately 17 feet and the slope height is approximately 20 feet (observed from the road). In the 2018 and 2019 upslope slide events, there were no injuries or damage to private property because there were no pedestrians or vehicles on the road. However, should a pedestrian or vehicle be on the road during an event, the road conditions do not allow for much area to avoid debris falling/sliding into the traveled way. To further complicate matters, the line-of-sight within these transects is inadequate, so reaction time will be very short. 14 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 Photograph 1. Soil landslide and uphill tree debris resulting from heavy rains in April 2018. Picture from County of Hawai‘i Civil Defense Agency (open source). Photograph 2. Transect F-W-01 looking uphill (north). Note the upslope road cut slope with vegetation. Waipi‘o Valley Road Preliminary Evaluation | 15 3140023002 January 2022 Photograph 3. Partially-vegetated road cut slope with exposed soil in upper slope area. Photograph 4. Exposed soil of upslope road cut slope face. Note overhanging soil and vegetation. Overhanging vegetation, exposed root systems 16 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 5.2 This section provides our evaluation of erosional/shallow failures in the area downslope of the Waipi‘o Valley Road guardrails. Based on our field observations and available information, the March 2019 slide (noted on Figures 2, 8, 9) appears to be a failure of the thin layer or “veneer” of side-cast fill and/or volcanic soil that overlies the bedrock. The natural slopes downhill of the road edge range from approximately 36 degrees to almost 50 degrees, and in the general area where the failure occurred it is approximately 43 degrees. These slope angles are steeper than the friction angle of most natural soils, and the soil cannot remain stable on the slope through friction alone. Cohesion of the clay and silt in the soils adds some resistance to downward movement. However, when exposed to water, soil strength decreases. In late August 2018, Hurricane Lane introduced enough water to decrease the soil veneer strength and exacerbate the conditions to a point where soil movement occurred at this location. It is important to note that seismic activity would also exacerbate instability with or without water saturation. Other factors may have played a role, including vegetation and stormwater infiltration. Vegetation from the guardrail or road edge all the way down to the slope toe and valley below is a combination of grasses, ferns, bushes, and small to mid-sized trees. Though vegetation can generally provide erosion control, the size and density of the flora may add to unstable conditions. Trees with shallow root systems can break up the soil veneer and provide preferential pathways for water seepage. If trees are top-heavy and topple over, then unprotected soil is exposed and infiltration pathways increase the potential for landslides. In addition, the road is an impermeable surface, which increases stormwater flow (volume and velocity) down the road and locally concentrates and directs flow over the slope. 6.0 The following subsections describe potential rockfall and soil slope mitigation alternatives for Waipi‘o Valley Road. 6.1 In general, rockfall mitigation alternatives presented in this report follow the approach hierarchy of (1) removal of risk; (2) stabilization of risk; and (3) protection from risk. In most cases, a combination of the three mitigation approaches is used to produce the most effective and feasible mitigation system. The removal approach physically eliminates the rockfall sources or source zones. This is typically done by rock removal, excavation, or reshaping the slopes with methods such as trim blasting, mechanical hoe ramming, boulder busting, scaling with prybars, use of an excavator bucket, or other mechanical means of removal. Removal approaches can also include relocating the roadway from the rockfall hazard zones. Stabilization consists of securing and/or reinforcing the rockfall source(s) to prevent rocks from moving or starting to fall. Commonly available methods include rock dowels and rock anchors, cable lashing, anchored rockfall netting, resin or cement grouting, shotcrete, and buttressing. Waipi‘o Valley Road Preliminary Evaluation | 17 3140023002 January 2022 Protection involves letting the source rocks fall, but intercepting, stopping, or retaining rockfall before it reaches the roadway. Techniques include excavating catchment ditches at the base of the slope, constructing soil berms/embankments, installing rockfall barriers and rockfall fences, and using mesh drapes that allow controlled rockfall descent. We qualitatively considered all these methods for the project area. We evaluated earthen berms and walls but there is not sufficient room for such structures in most areas of Waipi‘o Valley Road. Removing the rock source by excavation, scaling the hilltop (temporary and not as reliable), securing rock sources with anchored netting and/or locally doweling rocks in place, arresting rocks with fencing, and controlling rockfall with netting were all determined to be feasible options for at least one or more locations along the roadway. A discussion of these mitigation methods is provided below. 6.1.1 Excavation Excavation of the slope using blasting or mechanical rock removal techniques removes the rockfall risk above or adjacent to the roadway. If removal is extensive enough, it can also provide space to create a catchment ditch for rocks falling from upslope to land safely. Perimeter control techniques like pre-splitting (closely spaced drilled holes lightly loaded with explosives) or line drilling (very closely spaced holes that create a perforated edge without the use of explosives) create a planar cut-slope face at the designed orientation. The rock mass adjacent to the roadway can then be removed through drilling and blasting techniques or by using conventional excavating equipment if the rock mass is highly weathered and “rippable.” If sufficient room is created by rock removal, then a catchment ditch can be constructed at the toe of the slope. The surface of such a catchment ditch is typically covered with loose crushed stone to dampen the impact of potential falling rock. Reconfiguration of the roadway may be required to provide sufficient width for installation of catchment ditches. Such reconfiguration may include widening towards the downslope side of the roadway. Refer to Section 6.4 for information about widening the upslope side of the road. 6.1.2 Scaling Rock scaling is the procedure of removing loose rocks from the hillside and cliff face. Scaling is not considered a permanent method and would typically need to be conducted every 5 to 10 years to maintain its effectiveness, dependent on the specific site. Scaling should not be considered as reliable as structural methods since there is typically some subjectivity in selecting which rocks to remove. In addition, it is not always apparent what rocks are likely to fail within a specific time period. Scaling can be conducted mechanically if equipment can safely reach the specific rock areas from the roadway (e.g., overhangs directly adjacent to the road), though often scaling is done by hand by workers rappelling down the cliff face and prying rocks loose. 6.1.3 Localized Rockfall Stabilization Localized stabilization methods target rockfall source zones and include rock dowels, cable lashing, shotcrete, and anchored netting systems. Rock dowels are fully grouted steel bars that are not post-tensioned and secure specific unstable rock blocks. Cable lashing systems typically use wire rope to 18 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 stabilize rock blocks that cannot be doweled. Shotcrete (concrete propelled by a nozzle) can stabilize shear zones or highly weathered and fractured rock masses and are often paired with dowels or anchors. Anchored netting with erosion control matting, which is secured by boundary cables, cable anchors and patterned or targeted soil nails/rock dowels, can be used on combination soil and rock slopes or larger fractured rock masses. These methods would likely be used in conjunction with other mitigation methods. 6.1.4 Rockfall Fence Rockfall fences consist of high strength fences installed at the toe of a slope to “catch” falling rock. The fences are manufactured from steel components that have energy dissipation/absorption capabilities built into them. Typically, steel rings and sacrificial components are integrated into the fencing, which deform elastically and then plastically to stop rocks that impact the fence. The fences are generally constructed of posts that are connected to concrete footings or placed into concrete filled holes (where rock is present at the surface). The poles are guyed together laterally, and often in the upslope direction with steel cables. High strength steel fabric runs between the poles (similar to cyclone fencing, but much stronger) and is the primary element that the rock impacts. The rock energy is transferred to the fencing, which transfers it to the posts, cables, and ground anchors/foundations. Some energy is also dissipated by plastic deformation of the rockfall fence components. Rockfall fencing is designed based on three main characteristics: rock impact energy, rock bounce height, and site soil conditions. Rock impact energy and bounce height were estimated from the computer program RocFall, as noted in Section 4.3 of this report. Foundation conditions were not determined under the scope of this report but would be determined as part of additional work if fencing is selected as a mitigation strategy. 6.1.5 Rockfall Netting Rockfall netting consists of high strength steel fabric, similar to rockfall fence fabric; however, it is laid over the slope/source area and connected to the slope by cables and rock bolts, usually only along the top of the cliff. Generally, a fallout area is included in the design and the netting placed to allow rocks to drop behind the netting into the fallout area at the base of the cliff/source. This allows for maintenance/ removal of the rocks as needed and maintains the useful life of the netting. Rockfall netting is designed based on rock size, slope gradient, and area covered. Netting is selected that can control rocks of the size expected to be generated from the specific site. The netting must also be of a sufficient strength to support the weight of rocks that might lodge between the slope and netting, along with its own weight, a function of the slope gradient, as well as the dimensions of the area netted. Since netting is typically more expensive than fencing and more difficult to install, netting is typically used only where site conditions do not provide sufficient room for fence installation, such as along numerous stretches of the Lower Section of Waipi‘o Valley Road that are narrow. 6.1.6 Hybrid Fencing Systems A hybrid fencing system combines rockfall netting (described in Section 6.1.5) with rockfall fencing (described in Section 6.1.4) to attenuate, control and direct rockfall into a constructed catchment ditch at the base of the slope. The fencing system is configured with an open “throat,” supported by prop Waipi‘o Valley Road Preliminary Evaluation | 19 3140023002 January 2022 bars/fence posts, tie-back anchors, wire rope cables and end anchors. A high strength steel fabric is connected to the post and anchor system by a continuous upper support cable, and the netting drapes down the face of the slope unanchored. Typically, the terminal mesh end at the base of slope can be configured as open and unanchored, or finished with a fixed boundary cable to hold rockfall securely, reducing the possibility of rockfall bounce in the catchment ditch. 6.1.7 Concrete Barriers Concrete barriers are widely used along roadways to protect vehicles from roadside hazards, such as nearby obstructions, steep slopes, and rockfall. For rockfall, they are best suited to control low-impact energies and rollout from the ditch (Turner and Schuster 2012). They have a relatively low cost and narrow footprint. Additionally, they are typically readily available and easy to install. However, since Waipi‘o Valley Road is narrow and there is limited to no shoulder space along the upslope side of the road, this mitigation option is not feasible. 6.2 We evaluated the results of our analysis and found that different mitigation methods would be appropriate for each section (Upper, Central, and Lower). Table 7 below summarizes our general evaluation of typical measures. More in-depth discussions of suitable mitigation methods for each section are provided following the table. – Location/Method Applicability Notes/Comments Relative Cost Upper Section Long-term mitigation for the Upper Section upslope overhangs may include scaling back the vertical faces to a more stable angle, and rockfall drapery or anchored mesh installation with erosion control mats along the face of the exposed soil slope (refer to Section 6.3). Central and Lower Sections Excavation Substantial Risk Reduction Potentially difficult to construct May require localized stabilization of weathered rock/soil zones after construction Infrequent maintenance required Would allow roadway to be widened and straightened High Scaling Insufficient Risk Reduction Temporary solution only Not recommended alone Low, but cost would compound over time 20 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 Location/Method Applicability Notes/Comments Relative Cost Hybrid Fencing Substantial Risk Reduction Some excavation required at base of slope to create small catchment area Periodic maintenance required Moderate to high Anchored Netting with Upslope Fence Substantial Risk Reduction Anchored netting on exposed rock cuts adjacent to roadway, rockfall fencing upslope Periodic maintenance required Moderate to high Concrete Barrier Insufficient Risk Reduction Not recommended due to insufficient height Low 6.2.1 Upper Section Refer to soil slope stability recommendations made in Section 6.3.1. 6.2.2 Central and Lower Sections For long-term rockfall mitigation at Waipi’o Valley Road, we recommend trim blasting and excavating the upslope side rock slopes to expose less-weathered bedrock, create a catchment ditch for future rockfall retention, and improve roadway width and sightlines. It is anticipated that drilling and blasting operations would be necessary to conduct the excavation. Perimeter control techniques like pre-splitting or cushion blasting would be employed to construct a planar cut-slope face, while more typical production blasting methods would be used to remove the remaining rock. Post-blast stabilization methods, like shotcrete (with strip drains) or anchored netting may be necessary, particularly in highly weathered zones or at the interface of soil and bedrock. Specific details like the alignment of the rock cut, slope angle, catchment ditch width and configuration should be determined in subsequent project phases. 6.3 6.3.1 Upslope Soil Slope Mitigation Due to the history of and potential for soil slope failures on the downslope slope, we recommend the County consider temporary mitigation measures such as mandatory road closures to all non-local traffic during and after significant or prolonged rain events (for a period of days), removal of soil and vegetation overhangs from either the upslope (crews on ropes) or the road (using a cherry-picker, excavator) and, if feasible, cutting back the upslope areas to reduce the vertical face height. Waipi‘o Valley Road Preliminary Evaluation | 21 3140023002 January 2022 Long-term remedial actions could include rockfall drapery or anchored mesh installation with erosion control mats along the face of the exposed soil slope, and scaling back the vertical slope to a more stable angle (1.75H:1V or gentler), among other options. The County could also consider building a new road alignment to join the hairpin turn at the base of the slope in the Upper Section of the road. The existing portion of the road would be closed permanently to vehicle access, but it could be used for foot access if the overhead issues are addressed. The advantages of this option are the new alignment could be placed in a more reasonable location, an engineered design would be developed with adequate drainage, appropriate slope setbacks and/or overhead protection, wider travel lanes, separating foot and vehicle traffic, and to support heavier loads (tour buses, school buses, etc.). The disadvantages are that a new road would require several switchbacks to navigate the elevation change, and the installed costs may exceed the currently projected budget for the project. 6.3.2 Downslope Soil Slope Mitigation The downslope soil veneer is on average approximately 3 feet thick, which does not seem significant at first glance. However, the downhill slope face is estimated to be approximately 28 acres which amounts to an estimated 135,000 cubic yards of soil that could be subject to failure. Conditions similar to those that occurred during the March 2019 slide area exist across the entire downhill slope of the project site, and it is likely that other portions of the slope will fail without any intervention. We have indicated a generalized area of concern on Figure 9 to identify similar areas at risk based on available open-source LIDAR, topographic, and aerial information. However, a more detailed map should be developed based on a land survey of the area by a Land Surveyor licensed in the State of Hawai‘i along with field and lab evaluation of the soils to determine appropriate strength parameters for stability evaluations. Listed below are various measures that can be considered in managing the risk of slope failure (in general order of least to most complex). These measures can be combined to increase effectiveness. Unloading the top of the slope by removing top-heavy vegetation with shallow roots and replacing with deep-rooting grass such as vetiver. Re-grading the roadway so that water is not directed over the slope in a concentrated manner and/or designing a stormwater collection system to divert water away from the slope face and pipe it to an appropriate discharge point. Locally constructing retaining walls along the edge of the road, where limited shoulder width is present or downslope failures are present (refer to Section 6.4 for additional discussion regarding walls). Armoring/reinforcing the toe of the slope by building a fill buttress or using a combination of soil nails and shotcrete. Building a barrier at the toe of the slope that will hold back slide debris. 22 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 6.4 As noted in Section 6.3, retaining walls could be used to isolate the road from downslope failures or as noted in Section 6.1.1 may be used to widen the road to allow for installation of catchments at the toe of the uphill slopes. Furthermore, widening could provide better line-of-sight or provide the ability to install drainage improvements. Roadway widening on the downhill side could be achieved by the construction of retaining walls, including: Gabion wall, Mechanically Stabilized Earth (MSE) wall, and Cantilever soldier pile and lagging. Construction of any system may be challenging considering the limited horizontal width of the road, especially in the Lower Section. 6.4.1 Gabion Wall A gabion wall is a type of gravity retaining wall, similar to the lava rock walls at the site. It is constructed by stacking large wire baskets (rectangular prism) filled with rock. The gabion foundation base can be constructed by placing several baskets side-by-side. Construction continues by stacking baskets on top, tied together, and battered back at a slight angle. The advantages of a gabion wall are: The system is permeable and can be coupled with a drainage collection system to divert water away from the slope face; The baskets do not require concrete, which lessens the cost and logistics of materials and transport; Their relatively simple construction means that specialized equipment and labor are not necessary, and that construction may advance more quickly; The bedrock at the site is fairly shallow (< 6 feet bgs) and reasonably competent, so excavation for the foundation pad would not need to be deep; and Excavated native soil can be placed back to rebuild the road, if it is adequately conditioned and compacted. However, a disadvantage to the system is that part of the roadway width will be used to construct the wall. This in turn may require some cutback to the upslope area to regain the roadway width, or require the wall to be constructed further down the slope, resulting in a taller retaining wall. 6.4.2 Mechanically Stabilized Earth (MSE) Wall An MSE wall is a built-up soil retention wall with a precast concrete facing. The soil is placed in compacted layers and reinforced using either geosynthetics (geotextile fabric or grid) or metal reinforcing strips. They can be designed to support traffic on top of the reinforced soil mass, so roadway widening can be limited. Waipi‘o Valley Road Preliminary Evaluation | 23 3140023002 January 2022 The advantages of an MSE wall are similar to gabion walls, except that they are not as permeable, and materials may need to be procured off-island. Disadvantages of this system are that the road width may limit the possible reinforcement length, and significant off-haul of excavated material and import of select fill materials may be necessary if the onsite soil is not suitable for MSE backfill use. 6.4.3 Cantilever Soldier Pile Wall with Lagging A solider pile wall is constructed by embedding H-beams into a competent stratum, and then placing lagging or shotcrete between the piles to restrain the soil in between. When constructed for an excavation, it is done in a top-down manner. However, for Waipi‘o Valley Road, the wall would be installed from the guardrail, and piles would be placed some distance from the existing roadway edge, then backfilled to build up the road. The advantages of a soldier pile wall are the roadway can be widened and minimal excavation (drill spoils) would be required. Because the bedrock is fairly shallow, the pile lengths would not need to be very long. The disadvantages are that material costs are higher, specialized equipment and crews are necessary for construction (drill rigs and mobile crane to move piles into place), and pile and concrete placement and transport logistics will be considerable. 6.5 Pavement Visual inspection of the road surface of Waipi‘o Valley Road notes rutting and alligator cracking along much of its surface, and tension cracks parallel to the edge of pavement in some areas. Tension cracks are due to downward movement of the soil which may be the result of either the soil veneer moving downward or settlement of inadequately compacted soil underlying the road. Due to the vegetative cover, we were unable to observe obvious soil slumping or sagging along the slope face, so the cause is unknown. Hart Crowser was not provided information on the road structural section (asphalt concrete and aggregate base thickness). However, the type of damage indicates an inadequate structural section and the extent of damage would merit full-depth pavement reconstruction rather than chip seal, mill and fill, crack sealing, or other surficial repair methods. 7.0 Hart Crower, under contract with the County, conducted a preliminary geotechnical engineering evaluation to address roadway safety due to rockfall and slope instability hazards for Waipi‘o Valley Road. From June through September 2020, we conducted a field reconnaissance and on-rope rappels above and below the roadway in support of this evaluation. From this work, we concluded the following: Hazard ratings from RHRS scoring and RocFall modeling indicates mitigation for rockfall is recommended for the upslope side of the road. The bounce heights and energies of the modeled rockfall events for the Central and Lower Sections of the roadway could potentially cause vehicular 24 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 crashes and injuries or fatalities. Moreover, the risk of rockfall to pedestrians traveling on the road is considered unacceptable based on the AGS risk evaluation. The rockfall hazards in the Central and Lower Sections of the road would be effectively addressed by trim blasting and excavating the upslope side rock slopes to expose less-weathered bedrock, create a catchment ditch for future rockfall retention, and improve roadway width and sightlines. Along the Upper Section of the road, steep, exposed residual soil slopes are susceptible to instability as indicated by past failures, the most recent of which were upslope side landslides in April 2018 and February 2019. The instability is due to factors such as the slope steepness, exposure to water and wind, erodibility of the soil, and the proximity of top-heavy vegetation to the slope edge. Significant and prolonged rain events are likely to exacerbate these contributing risk factors. It is likely instabilities will occur along this portion of Waipi‘o Valley Road until these conditions are mitigated. We recommend the County consider temporary mitigation measures such as removal of overhangs and, if feasible, cutting back the upslope areas to reduce the vertical face height. While it is not feasible to predict the direct effect individual rainstorm events will have on slope hazards, the County may wish to consider temporary road closures to non-local traffic and/or road hazard advisories to residents when heavy rains are forecasted. Long-term mitigation actions could include rockfall drapery or anchored mesh installation along the face of the exposed soil slope, scaling back the vertical slope to a more stable angle (1.75H:1V or gentler), or changing the road alignment. Based on our field observations and available information, the March 2019 downslope slide appears to be a failure of the thin layer or “veneer” of volcanic soil which overlies the bedrock. The natural slopes downhill of the road range from approximately 36 degrees to almost 50 degrees, and in the general area where the failure occurred it is approximately 43 degrees. These slope angles are steeper than the friction angle of most natural soils, and the soil cannot remain stable on the slope through friction alone. When the slope is exposed to water, soil strength decreases. Other factors, such as vegetation and poorly controlled stormwater, may also have played a role. Conditions similar to those at the March 2019 slide area exist along most of the downhill slope of Waipi‘o Valley Road, and it is likely other downhill slope areas along the road could fail without intervention. Potential mitigation measures for these downslope areas may include vegetation replacement, stormwater improvements, wall construction, and/or slope reinforcement. The variety of upslope and downslope hazards along Waipio Valley Road mean the remedy(ies) will have to address several challenges to improve road safety. The mitigation options described in this preliminary evaluation can stabilize the road (upslope and downslope) and reduce the risk to vehicle and pedestrian travel from potential rockfall and slope instability. At a minimum, the upslope rock instability should be addressed so that risks to pedestrians and vehicles can be decreased. If the County moves forward with mitigation of the road, further discussion of preferred mitigation option(s) will be required to select the preferred alternative(s) prior to final design. Waipi‘o Valley Road Preliminary Evaluation | 25 3140023002 January 2022 8.0 Our report is for the exclusive use of the County of Hawai‘i for specific application to the subject project and site. We conducted this study in accordance with generally accepted geotechnical practices for the nature and conditions of the work conducted in the same or similar localities, at the time the work was performed. We make no warranty, express or implied. The work presented in this report is preliminary and conceptual only. A more detailed evaluation will be required for selection and design of mitigation options. 9.0 Australian Geomechanics Society (AGS). 2000. Landslide Risk Management Concepts and Guidelines. Australian Geomechanics Society (AGS). 2007. “The Australian GeoGuides for Slope Management and Maintenance. Australian Geomechanics Journal and News of the Australian Geomechanics Society, Volume 42 No 1. March. Bunce, C.M., Cruden, D.M. and Morgenstern, N.R. 1997. Assessment of the hazard from rockfall on a highway. Canadian Geotechnical Journal Vol. 34, No.3, pp.344-356. FHWA. 1993. Rockfall Hazard Rating System – Participant’s Manual, U.S. Department of Transportation, Federal Highway Administration, Publication No. FHWA-SA-93-057. Fletcher, C.H., E.E. Grossman, B.M. Richmond, and A.E. Gibbs. 2002. Atlas of Natural Hazards in the Hawaiian Coastal Zone, Geologic Investigations Series I-2761, U.S. Geological Survey, United States Government Printing Office. Harp, E.L., S.H. Hartzell, R.W. Jibson, L. Ramirez-Guzman, and R.G. Schmidt. 2014. Relation of Landslides Triggered by the Kiholo Bay Earthquake to Modeled Ground Motion, Bulletin of the Seismological Society of America, Vol. 104, No. 5, pp. 2529–2540. ‘i. Prepared for SSFM International by Hart Crowser, Inc. of Honolulu, HI. October 10. Jellinger, M. 1977. Methods of Detection and Analysis of Slope Instability, Southeast O‘ahu, Hawai‘i. University of Hawaii, Ph.D. Dissertation. Lamb, M.P., A.D. Howard, W.E. Dietrich, and J.T. Perron. 2007. Formation of amphitheater-headed valleys by waterfall erosion after large-scale slumping on Hawai‘i. GSA Bulletin; July/August 2007; v. 119; no. 7/8; p. 805–822; doi: 10.1130/B25986.1; 11 figures; 2 tables. Macdonald, G.A. and A.T. Abbot. 1970. Volcanoes in the Sea the Geology of Hawaii. Univ. Hawaii Press, Honolulu. Print. 26 | Waipi‘o Valley Road Preliminary Evaluation 3140023002 January 2022 Medley, E.W. 2007. Geological Engineering Reconnaissance of Damage Caused by the October 15, 2006 Hawaii Earthquakes. International Journal of Geoengineering Case histories, Vol.1, Issue 2, p.89-135. Namekar, S. 2013. Developing Tools for Earthquake-induced Landslide Hazard Maps of the Island of Dissertation. National Resource Conservation Service (NRCS). 2006. Waipi’o Valley Stream Management Plan. https://websoilsurvey.nrcs.usda.gov/app/WebSoilSurvey.aspx. Natural Resources Conservation Service (NRCS). 2018. Web-based soil survey visited February 27, 2018, Site Address: (www.websoilsurvey.nrcs.usda.gov/app). Sherrod, D.R., J.M. Sinton, S.E. Watkins, and K.M. Brunt. 2007. Geologic Map of the State of Hawai`i: U.S. Geological Survey Open-File Report 2007-1089, 83 p., 8 plates, scales 1:100,000 and 1:250,000, with GIS database. State of Hawai’i, Department of Defense (HDOD). -Hazard Mitigation Plan 2013 Update. Chapter 8, Landslides and Rock Falls, Civil Defense Division. Turner, A.K., Schuster, R.L. 2012. Rockfall: Characterization and Control, Transportation Research Board, Miscellaneous Publication, pg. 506. United States Geologic Survey (USGS). 2020. National Water Information System. https://maps.waterdata.usgs.gov/. Wolfe, E.W. and J. Morris. 1996. Geologic Map of the Island of Hawai‘i, U.S. Geological Survey, Map I-2524- A, scale 1:100,000. \\haleyaldrich.com\share\pdx_data\Notebooks\3140023002_Hawaii-Road_Slope_Evaluations\Deliverables\Reports\Final Waipio Report\Waipio_Geotechnical Engineering Evaluation_County Hawaii_Jan 2022.docx HAWAIʻI N !( !( !( Wailoa WailoaWailoaKaluahineFallsN !( ##N ## N Wailoa WailoaWailoaKaluahineFallsN !( !( !(WailoaWailoa WailoaKaluahineFallsN !( 3140023002 January202 APPENDIX A Field Data 3140023002 January202 Appendix A-1 Photograph Log Appendix A-1 – Waipi‘o Valley Road Photograph Log 1 of 15 Photo 1. Transect F-W-01, Upper Section. Photo 2. Transect F-W-02, Upper Section. Appendix A-1 – Waipi‘o Valley Road Photograph Log 2 of 15 Photo 3. Transect F-W-02, Upper Section. Note the residual overhang upslope of road. Photo 4. Transects F-W-03 and -04, Central Section. Note the pedestrians on the road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 3 of 15 Photo 5. Transect F-W-03, Central Section Area. Note road wear and some potential rock strikes. Photo 6. Transect F-W-04, Central Section. Note the rockfall on upslope side of road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 4 of 15 Photo 7. Transect F-W-04, Central Section. Jointed Basalt Outcrop with Residual. Photo 8. Transect F-W-04, Central Section. Guardrail strike from boulder or vehicle. Appendix A-1 – Waipi‘o Valley Road Photograph Log 5 of 15 Photo 9. Transect F-W-04, Central Section. March 2018 slide area. Photo 10. Transect F-W-05, Lower Section. Road narrows and reduced line-of-sight. Appendix A-1 – Waipi‘o Valley Road Photograph Log 6 of 15 Photo 11. Transect F-W-05, Lower Section. Looking uphill, note steep upslope basalt outcrop. Photo 12. Transect F-W-05, Lower Section. Note rock retaining wall makai side of road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 7 of 15 Photo 13. Transect F-W-05, Lower Section. Note guardrail dents from rockfall. Photo 14. Transect F-W-05, Lower Section. Note previous rockfall makai side of road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 8 of 15 Photo 15. Transect F-W-06, Lower Section. Steep Jointed Basalt outcrop with some residual. Photo 16. Transect F-W-06, Lower Section. Note the steep upslope and road deformation. Appendix A-1 – Waipi‘o Valley Road Photograph Log 9 of 15 Photo 17. Transect F-W-07, Lower Section. Jointed Basalt outcrop with infilling. Photo 18. Transect F-W-07, Lower Section. Note small deformed retaining wall makai side of road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 10 of 15 Photo 19. Transect F-W-08, Lower Section. Road narrows, Jointed Basalt with clinker zones observed upslope of road. Photo 20. Transect F-W-09, Lower Section. Jointed Basalt with clinker zones and infilling. Appendix A-1 – Waipi‘o Valley Road Photograph Log 11 of 15 Photo 21. Transect F-W-10, Lower Section. Line-of-sight issues continue downhill. Photo 22. Transect F-W-10, Lower Section. Surface water flow path mauka side of road. Appendix A-1 – Waipi‘o Valley Road Photograph Log 12 of 15 Photo 23. Transect F-W-10, Lower Section. Rockfall makai side of road. Photo 24. Transect F-W-11, Lower Section. Jointed Basalt with infilling. Appendix A-1 – Waipi‘o Valley Road Photograph Log 13 of 15 Photo 25. Transect F-W-11, Lower Section. Photo 26. Transect F-W-04, Central Section. Rappel work at slide area. Appendix A-1 – Waipi‘o Valley Road Photograph Log 14 of 15 Photo 27. Transect F-W-04, Central Section. Loose soil and rock debris over much of slide area. Photo 28. Transect F-W-04, Central Section. Base on slide area. Appendix A-1 – Waipi‘o Valley Road Photograph Log 15 of 15 Photo 29. Transect F-W-04, Central Section. Loose and rock debris at base of slide, setback from road to beach. Photo 30. Waipi‘o Valley Road slide area from beach road. 3140023002 January202 Appendix A-2 RHRS Data Sheet Table A 2.Waipio Valley Road RHRS Field Data Date 6/1/2020 6/1/2020 6/1/2020 6/1/2020 Transect No.F W 01 T/R F W 02 T/R F W 03 TFW04T/R Roadside (L/R)Mauka LLLL GPS Waypoint (NAD83)375155 N,2469404 E 375061 N,2469333 E 374971 N,2469102 E 375384 N,2468424 E GPS Elevation (MSL)(ft)937 826 850 670 Feature Beginning Location TP#1 Stream Channel TP#2 TP#5 Feature Ending Location Stream Channel TP#2 TP#5 TP#9 GPS Feature Length,feet 199 491 580 980 Measured Feature Length,feet 200 356 605 965 Feature Length,Average,feet 200 424 593 973 Feature Length,miles 0.04 0.08 0.11 0.18 Road Mile,Start 0.00 0.04 0.12 0.23 Road Mile,Finish 0.04 0.12 0.23 0.41 ADT (Waipio Lookout 2019)311 311 311 311 Posted Speed Limit 10 10 10 10 Average Vehicle Risk,%5101524 AVR Points 3333 Slope Height,measured 29 41 31 26 X (distance betweenand )19 17 29 16 Mauka Shoulder 0000 Makai Shoulder 0000 Height Instrument 6666 alpha,deg°70 65 65 66 beta,deg°40 45 44 34 Slope Height,calculated 17 19 7 6 Slope Height,selected 29 41 31 26 Slope Height Points 9999 Ditch Effectiveness No catchment No catchment No catchment No catchment Ditch Effectiveness Points 81 81 81 81 Roadway Width 19 17 29 16 Roadway Width Points 81 81 27 81 Sight Distance,N 95(H)93(V)80(V)93(V) Sight Distance,S 55(H)105(V)140(V)71(V) Sight Distance,actual 55 93 80 71 Sight Distance,decision 150 150 150 150 %Decision Sight Distance 37 62 53 47 %DSD Points 81 92727 Jointing irregular irregular irregular irregular Geology,name Basalt,Saprolite Basalt,Saprolite Basalt,Saprolite Basalt,Jointed Case 1,structural discont.,random (9) discont.,random (9) discont.,random (9) discont.,random (9) Case 1,friction clay infilling (81)clay infilling (81)clay infilling (81)undulating (9) Case 1,Points 81 81 81 9 Case 2,structural occasional (9)occasional (9)occasional (9)occasional (9) Case 2,erosion rates moderate (9)moderate (9)moderate (9)moderate (9) Case 2,Points 9999 Rocks/Boulders min size None None 0.5 0.5 avg size None None 0.9 1.0 max size None 1.0 1.5 1.3 Block Size,feet None 1.0 1.5 1.3 Volume,cubic yards 1.0 1.0 0.3 1.0 Block Size or Quantity Points 3399 Climate Points 27 27 27 27 Rockfall History 9999 TOTAL POINTS 375 303 273 255 Notes Location:From TP#1 to Stream Channel culvert.Debris flow slide volume measured at 1 cy. Seepage but minimal.Feature geologic description:BASALT with residual,moderately to severely fractured,extremely weathered (SAPROLITE),v.soft to soft. Location:From Stream Channel culvert to TP#2.Major erosion feature (overhang)at rim or crest of slope.No seepage observed.Feature geologic description:BASALT with residual (boulders), moderately to severely fractured,extremely weathered (SAPROLITE),v.soft to soft. Location:from TP#2 to TP#5. Slide feature on Makai side of road.Debris pile (~2cy)near TP#3.Largest rock (angular) measured 18"x12"x6".Feature geologic description:BASALT with some residual, moderately to severely fractured,extremely weathered (SAPROLITE),v.soft to soft. Location:from TP#5 to TP#9. Large boulder on Makai side of road measuring 7'x4'x4', undercut ~1 ft on downslope side.Feature geologic description:Jointed BASALT with infilling over entire feature,slightly to closely fractured,moderately to highly weathered,soft to m.hard.Additional line of sight measurements at transect: 160 ft north,95 ft south (vertical). Notes: TP =telephone pole H =horizontal line of sight V =vertical line of sight 1 TableA2.WaipioValleyRoad Date Transect No. Roadside (L/R)Mauka GPS Waypoint (NAD83) GPS Elevation (MSL)(ft) Feature Beginning Location Feature Ending Location GPS Feature Length,feet Measured Feature Length,feet Feature Length,Average,feet Feature Length,miles Road Mile,Start Road Mile,Finish ADT (Waipio Lookout 2019) Posted Speed Limit Average Vehicle Risk,% AVR Points Slope Height,measured X (distance betweenand ) Mauka Shoulder Makai Shoulder Height Instrument alpha,deg° beta,deg° Slope Height,calculated Slope Height,selected Slope Height Points Ditch Effectiveness Ditch Effectiveness Points Roadway Width Roadway Width Points Sight Distance,N Sight Distance,S Sight Distance,actual Sight Distance,decision %Decision Sight Distance %DSD Points Jointing Geology,name Case 1,structural Case 1,friction Case 1,Points Case 2,structural Case 2,erosion rates Case 2,Points Rocks/Boulders min size avg size max size Block Size,feet Volume,cubic yards Block Size or Quantity Points Climate Points Rockfall History TOTAL POINTS Notes Notes: TP =telephone pole H =horizontal line of sight V =vertical line of sight 6/1/2020 6/2/2020 6/2/2020 6/2/2020 F W 05 TFW06TFW07TFW08T LLLL 375932 N,2467709 E 376132 N,2467524 E 376254 N,2467372E 376325 N,2467240 E 393 381 350 337 TP#9 TP#11 ~70 ft S of TP#12 93 ft S of TP#13 TP#11 ~228 ft N of TP#11 93 ftS of TP#13 ~115 ft N of TP#13 432 312 191 263 419 228 170 225 426 270 181 244 0.08 0.05 0.03 0.05 0.41 0.49 0.55 0.58 0.49 0.55 0.58 0.63 311 311 311 311 10 10 10 10 10746 3333 28 28 26 26 20 15 15 11 0000 0000 6666 65 75 78 75 41 50 50 50 9181314 28 28 26 26 9999 No catchment No catchment No catchment No catchment 81 81 81 81 20 15 15 11 81 81 81 81 83(H)60(V)65(H)70(H) 70(H)43(V)40(H)80(V) 70 43 40 70 150 150 150 150 47 29 27 47 27 81 81 27 irregular irregular irregular irregular Basalt w/Residual Basalt Outcrop,Jointed Basalt Outcrop,Jointed Basalt,Jointed,w/Clinker discont.,random (9) discont.,random (9) discont.,random (9) discont.,random (9) clay infilling (81)undulating (9)undulating (9)undulating (9) 81999 occasional (9)occasional (9)occasional (9)occasional (9) moderate (9)small (3)small (3) small (3),moderate (9) 9999 0.7 0.4 None 1.3 0.85 0.7 None 1.3 1.0 1.1 None 1.3 1.0 1.1 None 1.3 1.0 0 None 0.5 3309 27 27 27 27 9999 321 303 300 255 Location:from TP#9 to TP#11. Transect located at sharp turn potentially planned for widening.Transmission lines located between TP#9 and TP#10.Feature geologic description:BASALT outcrop (steep)with residual,slightly to closely fractured,highly weathered,soft to m.hard. Vegetation includes grass, moss,and shrubs. Location:from TP#11 to ~228 ft north of TP#11.At transect, localized overhang at crest.19 ft max road width,9 ft narrowest road width.SW flow path observed ~100 ft north of TP#11.Minimal rockfall observed.Feature geologic description:Jointed BASALT with infilling,slightly to closely fractured,highly weathered,soft to m.hard. Line of sight measurement (vertical)made at TP#11. Additional line of sight measurement (horizontal)50 ft south and 50 ft north. Location:from ~70 ft south of TP#12 to 93 ft south of TP#13. Small retaining wall and SW flow feature at northend boundary of feature.Feature geologic description:Jointed BASALT outcrop with infilling, slightly to closely fractured, slightly to highly weathered, soft to m.hard.No seepage observed.Vegetation includes moss,ferns,small brush. Location:from 93 ft south of TP#13 to ~115 ft north of TP#13.SW flow path observed near north boundary of feature.Seasonal seepage in clinker zone near Stop sign. Feature geologic description: Jointed BASALT with clinker zones and infilling in lower portion of feature,slightly to closely fractured,moderate to highly weathered,soft to m.hard.Vegetation includes moss,small brush,and tree roots.Rockfall at SW flow feature only. 2 TableA2.WaipioValleyRoad Date Transect No. Roadside (L/R)Mauka GPS Waypoint (NAD83) GPS Elevation (MSL)(ft) Feature Beginning Location Feature Ending Location GPS Feature Length,feet Measured Feature Length,feet Feature Length,Average,feet Feature Length,miles Road Mile,Start Road Mile,Finish ADT (Waipio Lookout 2019) Posted Speed Limit Average Vehicle Risk,% AVR Points Slope Height,measured X (distance betweenand ) Mauka Shoulder Makai Shoulder Height Instrument alpha,deg° beta,deg° Slope Height,calculated Slope Height,selected Slope Height Points Ditch Effectiveness Ditch Effectiveness Points Roadway Width Roadway Width Points Sight Distance,N Sight Distance,S Sight Distance,actual Sight Distance,decision %Decision Sight Distance %DSD Points Jointing Geology,name Case 1,structural Case 1,friction Case 1,Points Case 2,structural Case 2,erosion rates Case 2,Points Rocks/Boulders min size avg size max size Block Size,feet Volume,cubic yards Block Size or Quantity Points Climate Points Rockfall History TOTAL POINTS Notes Notes: TP =telephone pole H =horizontal line of sight V =vertical line of sight 6/2/2020 6/2/2020 6/2/2020 F W 09 TFW10TFW11T LLL 376383 N,2466971 E 376420 N,2466849 E 376469 N,2466520 E 259 225 142 ~115 ft N of TP#13 75 ft N TP#14 95 ft S TP#17 75 ft N TP#14 95 ft S TP#17 TP#18 247 353 311 215 315 275 231 334 293 0.04 0.06 0.06 0.63 0.67 0.73 0.67 0.73 0.79 311 311 311 10 10 10 687 333 26 18 26 17 14 18 000 000 666 75 65 70 40 40 40 17 71 17 26 18 26 939 No catchment No catchment No catchment 81 81 81 17 14 18 81 81 81 65(H)83(H/V)82(H) 55(H)68(H/V)65(H) 55 68 65 150 150 150 37 45 43 81 27 27 irregular irregular irregular Basalt Outcrop,Jointed Basalt,Jointed Basalt Outcrop,Jointed discont.,random (9) discont.,random (9) discont.,random (9) undulating (9)undulating (9)undulating (9) 999 occasional (9)occasional (9)occasional (9) small (3)small (3)small (3) 999 0.3 0.5 0.4 0.3 1.2 0.7 0.3 2.0 1.0 0.3 2.0 1.0 0.25 0.33 0.25 393 27 27 27 999 303 249 249 Location:from ~115 ft N of TP#13 to 75 ft north of TP#14. Small SW flow path (#1)on the upper portion of feature ~60 ft south of TP#14.Second SW flow feature observed at north end of feature.Overhang at crest of slope and "void"with previous seepage observed at transect location.Old concrete guardrails seen below (Makai side)road near #1 SW flow path.Feature geologic description:Jointed BASALT outcrop with infilling,slightly to closely fractured,moderate to highly weathered,soft to m.hard.Vegetation includes moss,grass,and small brush. Location:75 ft north of TP#14 to 95 ft south of TP#17. Transect located ~40 ft south of TP#15.SW flow path (#1) ~50 ft north of TP#15 and includes fallen tree.SW flow path (#2)~95 ft south of TP#17.19 ft maximum road width and 12 ft narrowest road width.Second line of sight (H/V)85 ft north and 80 ft south.Feature geologic description:Jointed BASALT with infilling,slightly to closely fractured,moderately weathered,soft to m.hard. Vegetation includes moss, ferns,shrubs and tree roots. Location:from 95 ft south of TP#17 to TP#18.Significant SW flow path at TP#18.Transect ~20 ft south of TP#17.Rock outcrop and source area ~80 ft south TP#18.Small collapsible void north of transect location.Feature geologic description:Jointed BASALT with infilling,slightly to closely fractured,moderate to highly weathered,soft to m.hard. 3 3140023002 January202 Appendix A-3 Rappel Traverse Data Date: 8/27/2020Name: WaipioRappel1,WR1Description: Primaryslide,downslopetraverseCellID4TopofCell5(ft)BottomofCell5(ft)CellLength(ft)CellGradient6(Degrees)CellGradient(Radians)CellType CellMaterial CellDescription VegetationType VegetationDescription Veg.Height Veg.Spacing Veg.DiameterTP0466030.97 1610530.597 592.148TP02000.0n/awidthofroad20'TP1466045.018 1610519.862 590.072TP100200.00.020.0 20.0 0.0(road)asphaltconcrete(WaipioValleyRoad)topofWR1,70'wide,edgeofroadaboveMarch2019slideTP2466057.801 1610496.576 563.98TP20454541.60.733.7 53.7 29.9slopescarp/failuresourceGrass/Ferns<1'3'+<2'8'<0.5"TP3466126.497 1610392.205 445.732TP345220 175 43.00.8128.0 181.6 119.3 75.2 slopesaprolitewithresidualsoilandcobbles15'outcropbelowTP3TP4466132.082 1610386.203 434.694TP4220 2351557.61.08.0 189.7 12.7 62.6 slopebedrock/saproliteexposedbedrocksection Shrubs/Bushes smallplantsandvines 4'+dense<1"TP5466144.131 1610373.869 424.404TP5235 2552032.80.616.8 206.5 10.8 51.7 slopebedrock/saprolitewithcobblesShrubs/Bushes densevines6'7'+<1"TP6466179.869 1610332.874 377.562TP6255 3307543.60.854.3 260.8 51.70slopebedrock/saprolitewithvegbedrockbenchatbottom Shrubs/Bushes smallplantsandvines6'7'+dense<1"Notes:2. ElevationvaluesinMSL.3. MaxPDOP=MaximumPositionDilutionofPrecision.GreaterpositionaccuracyforlowerPDOPvalue.GreatererrorinhigherPDOPvalues.4. CellID=CellIdentificationrepresentsazoneofsimilarslopegradient,vegetationmaterial,and/orthepresenceofoutcropsorsourcerock.5. TopandBottomofCellwerephysicallymeasuredinthefieldfromthestartofrappel/upgradientlocation.6. CellGradientswerephysicallymeasuredinthefieldandrecordedindegreesofslope.7. HorizontalDistancerepresentsdistanceofcellalongtheXAxisplane(horizontalaxis)8.VerticalDistancerepresentsdistanceofacellalongtheYAxisPlane(verticalaxis)GPSID=GPSIdentificationTP1=TransectPointNumber1OC1=OutcropPointNumber1CellMaterialCellVegetation1. CooridnatesandelevationsreportedusingNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet).HorizontalDistance7(ft)TotalHorizontalDistance(ft)VerticalDistance8(ft)TotalVerticalDistance(ft)GPSIDNorthing1Easting1Elevation2CellInformation Date: 8/31/20209/1/2020Name: WaipioRappel3,WR3Description: TraverseupslopeofWaipioValleyRoadCellID4TopofCell5(ft)BottomofCell5(ft)CellLength(ft)CellGradient6(Degrees)CellGradient(Radians)CellType CellMaterial CellDescription VegetationType VegetationDescription Veg.Height Veg.Spacing Veg.DiameterTP1464633.958 1609943.774 996.501TP10000.00.0Other n/aWR3,accesstrail,topofrappelTrees sb(strawberry)guava <15'<3'5'+ <2"3",5"9"+TP1b464687.295 1609842.292 914.874TP1b0142 142 39.00.7110.4 110.4 89.4Slopesoilslopewithvegtransitiontogullybench Treessbguava<15'<3'5'+ <2"3",5"9"+TP1c464693.708 1609835.428 896.829TP1c142 1561456.01.07.8 118.2 11.6SlopesoilslopewithvegbottomoftransitiontogullybenchTreessbguava<15'<3'5'+ <2"3",5"9"+TP2464729.205 1609789.874 869.451TP2156 2176136.00.649.4 167.5 35.9SlopesoilslopewithvegTrees sbguava,eucalyptus,tileaf <15'+<3'5'+<1"3"+,1'TP3464743.645 1609772.153 815.218TP3217 2755839.60.744.7 212.2 37.0 567.8 SlopesoilslopewithvegTrees sbguava,eucalyptus,tileaf <15'+<3'5'+<1"3"+,1'TP4464849.99 1609633.066 706.193TP4275 420 145 39.00.7112.7 324.9 91.3 530.8 Slopesoilslopewithveg5'eastofgullyTreeseucalyptus,lesssbguava,moretileaf<15'+<3'5'+<1"3"+,1'EP1464822.095 1609653.989 707.749TP4b4204836329.60.554.8 379.7 31.1439.6Slopesoilslopewithvegincisedgully:highlyweatheredbasaltandcolluviumTreeseucalyptus,lesssbguava,moretileaf<15'+<3'5'+<1"3"+,1'TP5[OC1/2/3]464907.802 1609575.603 595.954TP5483 613 130470.888.7 468.3 95.1 408.5 SlopesoilslopewithvegincisedgullyMixedsbguava,xmas(christmas)berry,ferns15'+<10'20'+ <2"3",5"9"+TP6465004.754 1609498.904 484.227TP6613 781 168460.8116.7 585.0 120.8 313.4 Slopesoilslopewithvegandoutcropsvariousrockfalldeposits:cobblestobouldersongullybenches,1.5'x1'x0.5'Mixed sbguava,xmasberry,ferns 15'+<10'20'+ <2"3",5"9"+TP7465041.207 1609465.607 460.09TP7781 83857400.743.7 628.7 36.6 192.5 Slopesoilslopewithvegandoutcropsoutcropsin/alonggully;multiplefallentreesingullyMixed sbguava,xmasberry,ferns 15'+<10'20'+ <2"3",5"9"+TP7b465048.852 1609465.354 458.738TP7b838 843500.05.0 633.7 0.0 155.9 BenchsoilslopewithvegandoutcropsbenchbetweenTP7andTP8Treessbguava,ironwoodtreeswithneedlebedonground15'30'+5'10'+<2"14"TP8465061.283 1609461.55 397.028TP8843 88845500.928.9 662.6 34.5 155.9 Slopeoutcropscoveredbysoil/vegdebrisaboveverticalsection Treessbguava,ironwoodtreeswithneedlebedonground15'30'+5'10'+<2"14"TP9465090.065 1609452.018 346.891TP9888 94153631.124.1 686.7 47.2 121.4 Slopeoutcropscoveredbysoil/vegdebrisweatheredbasaltoutcropwithveg/debrisTrees xmasberrytrees,ferns<5',10'15'+10'+0.5'1'+TP9b465103.635 1609436.491 368.229TP9b941 9511000.010.0 696.7 0.0 74.2 Benchoutcropscoveredbysoil/vegdebrisweatheredbasaltoutcropwithveg/debrisTrees xmasberrytrees,ferns <5',10'15'+10'+0.5'1'+TP10465119.648 1609438.197 298.047TP10951 99039520.924.0 720.7 30.7 74.2 Slopeoutcropscoveredbysoil/vegdebrisweatheredbasaltoutcropwithveg/debrisTrees xmasberrytrees,ferns <5',10'15'+10'+0.5'1'+TP11465134.7441609433.153 274.25TP11990 1021 31601.015.5 736.2 26.8 43.5 Slopeoutcropscoveredbysoil/vegdebrisweatheredbasaltoutcropwithveg/debrisTreesxmasberrytrees,sbguava,ferns<5',10'15'+10'+0.5'1'+TP12465136.381 1609426.883 261.166TP121021 1038 17781.43.5 739.7 16.6 16.6 Outcrop roadcut TP12onWaipioValleyRoadTP13465147.169 1609423.09 270.862TP131038 1049 1100.011.0 750.7 0.0 16.6 (road)asphaltconcreteHorizontalDistance7(ft)TotalHorizontalDistance(ft)VerticalDistance8(ft)TotalVerticalDistance(ft)GPSIDNorthing1Easting1Elevation2CellInformationCellMaterialCellVegetation Date: 8/31/20209/1/2020Name: WaipioRappel3,WR3Description: TraverseupslopeofWaipioValleyRoadGPSIDNorthing Easting ElevationOutcropTapedDistance OutcropWidthOutcropHeight RockTypeRockDescription JointStrike JointDip Spacing Persistence Aperture JointRoughness i,1stOrderRoughness Weathering InfillingSource? NotesSchmidtHammerValue9OC1464889.659 1609604.533 634.926 OC1560basaltweatheredbasaltoutcrop/bouldersvariable variable <1'1.5' <1'1.5' >1/8""RoughUndulatingmoderatelytohighlyweathered Organic,soilYesSubangularblocks/boulders.11*OC2464885.384 1609580.886 623.021 OC2588basaltweatheredbasaltoutcrop/bouldersvariable variable <2'4' <2'4' <1'YesSubroundedblocks/boulders.Climbersrightofincisedgully.OC3464903.644 1609566.081 577.551 OC3627basaltweatheredbasaltvariable variable <1'1.5',2' <1'1.5',2'YesSubangularblocks/boulders.Boulder:(2.5'x1'x1.5')GPSIDNorthingEasting Elevation ErosionPointTapedDistanceHorizontalLengthVerticalLength SlopeGradient SlideGradient SlideDepth SoilDepth SoilType RockTypeRockWeatheringRockInfilling VegetationTracktoFlowFeature?EstimatedCauseEstimatedCauseCommentsNotesEP1 464822.095 1609653.989 707.749 EP1tape420'483',headtotoe7300 29.6000004 90Otherhighlyweatheredbasaltandcolluviumnaturalsurfaceflow,ephemeralstreamsheadofincisedgullyEP2 464852.66 1609622.112 701.215 EP2tape498'attoe5130551.50highlyweatheredbasaltandcolluviummossnaturalsurfaceflow,ephemeralstreamsincisedgullyNotes:2. ElevationvaluesinMSL.3. MaxPDOP=MaximumPositionDilutionofPrecision.GreaterpositionaccuracyforlowerPDOPvalue.GreatererrorinhigherPDOPvalues.4. CellID=CellIdentificationrepresentsazoneofsimilarslopegradient,vegetationmaterial,and/orthepresenceofoutcropsorsourcerock.5. TopandBottomofCellwerephysicallymeasuredinthefieldfromthestartofrappel/upgradientlocation.6. CellGradientswerephysicallymeasuredinthefieldandrecordedindegreesofslope.7. HorizontalDistancerepresentsdistanceofcellalongtheXAxisplane(horizontalaxis)8. VerticalDistancerepresentsdistanceofacellalongtheYAxisPlane(verticalaxis)9. CorrectedSchmidtHammerreadingsprovided.Valueswithasteriskarereferencevaluesbasedonanaverage.SeeSchmidtHammerReadingssheet.10. LidardatainNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet).GPSID=GPSIdentificationTP1=TransectPointNumber1OC1=OutcropPointNumber11. CoordinatesandelevationsreportedusingNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet). Date: 9/2/20209/3/2020Name: WaipioRappel4,WR4Description: TraverseupslopeofWaipioValleyRoadCellID4TopofCell5(ft)BottomofCell5(ft)CellLength(ft)CellGradient6(Degrees)CellGradient(Radians)CellType CellMaterial CellDescription VegetationType VegetationDescription Veg.Height Veg.Spacing Veg.DiameterTP0464828.98 1610111.695 1019.89TP0000.00.00.00.00.0Other n/astartofrappelTP1464817.555 1610063.194 974.399TP10585828.40.551.0 51.0 27.6SlopesoilslopewithtreesandvegdebrisTreessb(strawberry)guava,eucalyptus<25'+<5'20'+ <2"4"+,12"+TP2[EP1]464885.633 1609985.319 929.736TP258187 129 38.00.7101.7 152.7 79.4Slopesoilslopewithsoilandveg/debrisincisedgully:steppedoutcrops/benchesingullysbguava,africantulip,tileaf,ferns<20'+<3'5'+<2"4"+TP3464923.332 1609966.763 846.026TP3187 2556840.00.752.1 204.8 43.7Slopesoilslopewithveg/debrisincisedgullyTreessbguava,africantulip,tileaf,ferns<20'+<3'5'+<2"4"+TP4[EP2]464952.822 1609941.417 790.949TP4255 3206545.00.846.0 250.7 46.0Slopesoilslopewithveg/debrisincisedgullyTreesxmas(christmas)berry,tileaf,sbguava,ferns<5'15'+<2'5'+ <2"4"+,12"+TP5465005.381 1609877.201 722.27TP5320 427 107 41.00.780.8 331.5 70.2SlopesoilslopewithvegTreesxmasberry,tileaf,sbguava,ferns<5'15'+<2'5'+ <2"4"+,12"+TP6465109.971 1609759.864 591.063TP6427 639 212 48.00.8141.9 473.3 157.5SlopesoilslopewithvegTreesxmasberry,sbguava,hau,tileaf,africantulip<10'20'+dense,<20' <6"12"+TP7465170.102 1609685.603 629.958TP7639 7076843.00.849.7 523.1 46.4SlopesoilslopewithvegincisedgullyTreesxmasberry,sbguava,hau,tileaf,africantulip<10'20'+dense,<20' <6"12"+TP7b465168.754 1609710.238 521.316TP7b707 7322557.61.013.4 536.5 21.1Outcrop outcrop steppedoutcropTP8[OC1]465174.234 1609697.663 473.422TP8732 7814948.80.932.3 568.7 36.9Slopeslopewithoutcropscoveredwithsoil/vegweatheredbasalt Treesdensexmasberry,sbguava,tileaf,ferns,soapbush/koster'scurse<8'20'+<3'8'+ <2"4"+,12"+TP9465210.621 1609662.321 411.639TP9781 8607948.00.852.9 621.6 58.7SlopesoilslopewithvegoutcropingullyTreesdensexmasberry,sbguava,tileaf,ferns,soapbush/koster'scurse<8'20'+<3'8'+ <2"4"+,12"+TP10a[OC2]465259.003 1609586.977306TP10860 988 128 56.01.071.6 693.2 106.1SlopeoutcropsslopewithvegslightlytomoderatelyweatheredbasaltTreesdensexmasberry,sbguava,tileaf,ferns,soapbush/koster'scurse<8'20'+<3'8'+ <2"4"+,12"+TP10b[OC3]465259.003 1609586.977 287.717TP11988 1006 1888.01.50.6 693.8 18.0OutcropTP11465271.078 1609579.791 308.931TP121006 1016 100.00.015.0 708.8 0.0(road)asphaltconcreteNotes:2. ElevationvaluesinMSL.3. MaxPDOP=MaximumPositionDilutionofPrecision.GreaterpositionaccuracyforlowerPDOPvalue.GreatererrorinhigherPDOPvalues.4. CellID=CellIdentificationrepresentsazoneofsimilarslopegradient,vegetationmaterial,and/orthepresenceofoutcropsorsourcerock.5. TopandBottomofCellwerephysicallymeasuredinthefieldfromthestartofrappel/upgradientlocation.6. CellGradientswerephysicallymeasuredinthefieldandrecordedindegreesofslope.7. HorizontalDistancerepresentsdistanceofcellalongtheXAxisplane(horizontalaxis)8. VerticalDistancerepresentsdistanceofacellalongtheYAxisPlane(verticalaxis)9. CorrectedSchmidtHammerreadingsprovided.Valueswithasteriskarereferencevaluesbasedonanaverage.SeeSchmidtHammerReadingssheet.10. LidardatainNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet).GPSID=GPSIdentificationTP1=TransectPointNumber1OC1=OutcropPointNumber11. CoordinatesandelevationsreportedusingNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet).HorizontalDistance7(ft)TotalHorizontalDistance(ft)VerticalDistance8(ft)TotalVerticalDistance(ft)GPSIDNorthing1Easting1Elevation2CellInformationCellMaterialCellVegetation Date: 9/2/20209/3/2020Name: WaipioRappel4,WR4Description: TraverseupslopeofWaipioValleyRoadGPSIDNorthing Easting Elevation OutcropTapedDistanceOutcropWidthOutcropHeightRockTypeRockDescriptionJointStrike JointDip Spacing Persistence Aperture JointRoughness i,1stOrderRoughness WeatheringInfillingSource?NotesSchmidtHammerValue9OC1465161.594 1609702.616 502.024 OC1 707'752'45' basaltweatheredbasaltYesbouldersource,7'x4'x4.5',subangular32,34OC2465239.349 1609630.664 387.6 OC2 900'pahoehoe,massivebasalt5,278,350,349.82,50,8976W,87N,61E,84W,83NW,64SE,81NW6"12" <3'Yesboulders:(1'2'x1'x1'),(2'x1.3'x0.1'1',tapers)localizedjointinginpahoehoe,otherwisemassivebasalt30OC3988'1006'18'pahoehoe,massivebasalt269,35785NW,88WGPSIDNorthing Easting Elevation ErosionPointTapedDistanceHorizontalLengthVerticalLength SlopeGradient SlideGradient SlideDepth SoilDepth SoilType RockTypeRockWeatheringRockInfilling VegetationTracktoFlowFeature?EstimatedCauseEstimatedCauseCommentsNotesEP1464855.3361610023.86 975.746 EP1113'4004021 residualsoilhighlyweatheredbasalthighlyweatheredtosaprolitesoilandorganics/mossmossonrocksYesnaturalsurfaceflow,ephemeralstreamsincisedgullyEP2464931.616 1609954.288 831.932 EP2 255'277' 6.50406541.5 residualsoilhighlyweatheredtosaprolitebasalthighlyweatheredtosaprolitesoilandorganicsYesnaturalsurfaceflow,ephemeralstreamsincisedgullyNotes:2.ElevationvaluesinMSL.3. MaxPDOP=MaximumPositionDilutionofPrecision.GreaterpositionaccuracyforlowerPDOPvalue.GreatererrorinhigherPDOPvalues.4. CellID=CellIdentificationrepresentsazoneofsimilarslopegradient,vegetationmaterial,and/orthepresenceofoutcropsorsourcerock.5. TopandBottomofCellwerephysicallymeasuredinthefieldfromthestartofrappel/upgradientlocation.6. CellGradientswerephysicallymeasuredinthefieldandrecordedindegreesofslope.7. HorizontalDistancerepresentsdistanceofcellalongtheXAxisplane(horizontalaxis)8. VerticalDistancerepresentsdistanceofacellalongtheYAxisPlane(verticalaxis)9. CorrectedSchmidtHammerreadingsprovided.Valueswithasteriskarereferencevaluesbasedonanaverage.SeeSchmidtHammerReadingssheet.10. LidardatainNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet).GPSID=GPSIdentificationTP1=TransectPointNumber1OC1=OutcropPointNumber11. CoordinatesandelevationsreportedusingNorthAmericanDatum1983(NAD83)StatePlaneHawaii1FIPS5101(Feet). 3140023002 January202 APPENDIX B Rockfall Evaluation Data TP-1b TP-2TP-1c TP-1a TP-3 EP-1 TP-4 TP-5 TP-6 TP-7b TP-7 TP-8 TP-9 TP-9b TP-10 TP-11 TP-12 TP-1312001000800600400 2000 200 400 600 800 1000 1200 1400 1600 1800 Analysis Description Traverse WR3 - Existing Conditions, Static Scenario Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 Line Seeder: TP-4, EP-1, EP-2 Line Seeder: TP-5, OC-1, OC-2, OC-3 Line Seeder: Bench - TP-7 Line Seeder: Bench - TP-8, TP-9 Line Seeder: Bench - TP-9b Line Seeder: TP-10, TP-11 Line Seeder: Roadcut Waipi'o Valley Road Data Collector: Edge of Pavement Hawaii Basalt and Slope adjacent to Roadway Soil Slope with Vegetation Outcrops with Soil and Vegetation Soil Slope with Veg, Boulders, and Outcrop Notes: 1. Rock blocks thrown for this model assume static conditions of the slope with no horizontal velocity impetus applied to the rocks. 2. Rounded hexagon and rhombus-shaped rock blocks were used in the model. Density of the rock blocks (Hawaii Basalt) is assumed to be 170 pcf. 0 20 40 60 80 100 120 140 160 180 200 220 240 0 100 200 300 400 500 600 700 800Number of RocksLocation [ft] 200 300 400 500 600 700 800 900 1000 Slope Y LocationDistribution of Rock Path End Locations Total number of rock paths: 967 Rocks Slope Rock Start Analysis Description Traverse WR3 - Existing Conditions, Static Scenario Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 10 20 30 40 50 60 70 80 90 100 110 120 130 2 3 4 5 6 7 8 9 10 11 12 13Number of RocksImpact Along Height [ft] Impact Along Height on EOP Total number of rocks on EOP: 343Impact Along Height: min = 2.34567, max = 12.6299 Number of Rocks Analysis Description Traverse WR3 - Existing Conditions, Static Scenario Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 10 20 30 40 50 0 10000 20000Number of RocksTranslational Kinetic Energy [ft-lb] Translational Kinetic Energy on EOP Total number of rocks on EOP: 343Translational Kinetic Energy: min = 48.1157, max = 26987.3 Number of Rocks Analysis Description Traverse WR3 - Existing Conditions, Static Scenario Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 TP-1b TP-2TP-1c TP-1a TP-3 EP-1 TP-4 TP-5 TP-6 TP-7b TP-7 TP-8 TP-9 TP-9b TP-10 TP-11 TP-12 TP-1312001000800600400 2000 200 400 600 800 1000 1200 1400 1600 1800 Analysis Description Traverse WR3 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 Line Seeder: TP-4, EP-1, EP-2 Line Seeder: TP-5, OC-1, OC-2, OC-3 Line Seeder: Bench - TP-7 Line Seeder: Bench - TP-8, TP-9 Line Seeder: Bench - TP-9b Line Seeder: TP-10, TP-11 Line Seeder: Roadcut Waipi'o Valley Road Data Collector: Edge of Pavement Hawaii Basalt and Slope adjacent to Roadway Soil Slope with Vegetation Outcrops with Soil and Vegetation Soil Slope with Veg, Boulders, and Outcrop Notes: 1. Rock blocks thrown for this model assume a horizontal velocity impetus for rock motion of 10 ft/s (like a significant rainfall event, debris flow, earthquake, etc.). 2. Rounded hexagon and rhombus-shaped rock blocks were used in the model. Density of the rock blocks (Hawaii Basalt) is assumed to be 170 pcf. 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 0 100 200 300 400 500 600 700 800Number of RocksLocation [ft] 200 300 400 500 600 700 800 900 1000 Slope Y LocationDistribution of Rock Path End Locations Total number of rock paths: 989 Rocks Slope Rock Start Analysis Description Traverse WR3 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 10 20 30 40 50 60 70 80 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19Number of RocksImpact Along Height [ft] Impact Along Height on EOP Total number of rocks on EOP: 517Impact Along Height: min = 2.52041, max = 17.5865 Number of Rocks Analysis Description Traverse WR3 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 10 20 30 40 50 60 70 80 90 100 0 10000 20000 30000 40000 50000Number of RocksTranslational Kinetic Energy [ft-lb] Translational Kinetic Energy on EOP Total number of rocks on EOP: 517Translational Kinetic Energy: min = 1735.29, max = 47994.5 Number of Rocks Analysis Description Traverse WR3 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR3-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 TP-0 TP-1 TP-2 TP-3 TP-4 TP-5 TP-6 TP-7 TP-7b TP-8 TP-9 TP-10a TP-10b TP-1112001000800600400 2000 200 400 600 800 1000 1200 1400 1600 1800 Analysis Description Traverse WR4 - Existing Conditions, Static Conditions Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 Point Seeder: TP-2 Point Seeder: TP-5 Line Seeder: TP-10a, OC-1 Data Collector: Edge of Pavement Line Seeder: Roadcut Notes: 1. Rock blocks thrown for this model assume static conditions of the slope with no horizontal velocity impetus applied to the rocks. 2. Rounded hexagon and rhombus-shaped rock blocks were used in the model. Density of the rock blocks (Hawaii Basalt) is assumed to be 170 pcf. Slope Adjacent to RoadwaySoil Slope with Vegetation Hawaii Basalt Outcrops with Soil and Vegetation Waipi'o Valley Road Point Seeder: OC-1 Line Seeder: Bench - TP-7 0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 0 100 200 300 400 500 600 700 800Number of RocksLocation [ft] 200 300 400 500 600 700 800 900 1000 1100 Slope Y LocationDistribution of Rock Path End Locations Total number of rock paths: 899 Rocks Slope Rock Start Analysis Description Traverse WR4 - Existing Conditions, Static Conditions Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 2 4 6 8 10 12 14 16 18 20 22 24 22 23 24 25 26Number of RocksImpact Along Height [ft] Impact Along Height on EOP Total number of rocks on EOP: 44Impact Along Height: min = 22.3492, max = 25.91 Number of Rocks Analysis Description Traverse WR4 - Existing Conditions, Static Conditions Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 -1000 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000Number of RocksTranslational Kinetic Energy [ft-lb] Translational Kinetic Energy on EOP Total number of rocks on EOP: 44Translational Kinetic Energy: min = 9.57296, max = 12168.4 Number of Rocks Analysis Description Traverse WR4 - Existing Conditions, Static Conditions Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 TP-0 TP-1 TP-2 TP-3 TP-4 TP-5 TP-6 TP-7 TP-7b TP-8 TP-9 TP-10a TP-10b TP-1112001000800600400 2000 200 400 600 800 1000 1200 1400 1600 1800 Analysis Description Traverse WR4 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 Notes: 1. Rock blocks thrown for this model assume a horizontal velocity impetus for rock motion of 10 ft/s (like a significant rainfall event, debris flow, earthquake, etc.). 2. Rounded hexagon and rhombus-shaped rock blocks were used in the model. Density of the rock blocks (Hawaii Basalt) is assumed to be 170 pcf. Point Seeder: TP-2 Point Seeder: TP-5 Point Seeder: OC-1 Line Seeder: TP-10a, OC-1 Data Collector: Edge of Pavement Line Seeder: Roadcut Slope Adjacent to RoadwaySoil Slope with Vegetation Hawaii Basalt Outcrops with Soil and Vegetation Waipi'o Valley Road Line Seeder: Bench - TP-7 0 100 200 300 0 100 200 300 400 500 600 700 800Number of RocksLocation [ft] 200 300 400 500 600 700 800 900 1000 1100 Slope Y LocationDistribution of Rock Path End Locations Total number of rock paths: 972 Rocks Slope Rock Start Analysis Description Traverse WR4 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 10 20 30 40 50 60 23 24 25 26Number of RocksImpact Along Height [ft] Impact Along Height on EOP Total number of rocks on EOP: 135Impact Along Height: min = 22.391, max = 25.9056 Number of Rocks Analysis Description Traverse WR4 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012 0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 0 1000 2000 3000 4000 5000 6000 7000 8000 9000 10000 11000 12000 13000Number of RocksTranslational Kinetic Energy [ft-lb] Translational Kinetic Energy on EOP Total number of rocks on EOP: 135Translational Kinetic Energy: min = 457.477, max = 11981.5 Number of Rocks Analysis Description Traverse WR4 - Existing Conditions with Horizontal Velocity Company Haley & Aldrich, Inc. Drawn By A. Granger and N. Lescalleet File Name 135500-003_WR4-Traverse.fal8DateNovember 2020 Project Laupahoehoe Point and Waipi'o Valley Road Project ROCFALL 8.012