MANUAL FOR ROCKFALL INVENTORY PREPARED BY:

Transcription

1 MANUAL FOR ROCKFALL INVENTORY PREPARED BY: THE OHIO DEPARTMENT OF TRANSPORTATION OFFICE OF GEOTECHNICAL ENGINEERING 1980 WEST BROAD STREET COLUMBUS, OHIO DECEMBER 2016

2 TABLE OF CONTENTS SECTION 100 INTRODUCTION... 1 SECTION 200 ROCK SLOPE INVENTORY AND DATA COLLECTION PURPOSE AND GENERAL PROCESS SITE INVENTORY AND PRELIMINARY RATING General Office Procedures ODOT Interview(s) Digital Photolog Other Photographic Alternatives Geological Reference Field Procedures Inventory Site Determination a) Site Determination for Ramps Preliminary Rating of Inventory Site a) Inventory Site Location aa) Beginning Mile Point (BMP) bb) Inventory Site Length cc) Ending Mile Point (EMP) dd) BMP Position Preliminary Rating Scoring TIER 1 DATA COLLECTION Field Procedures Slope Configuration Figure EXAMPLES OF CUT SLOPES Slope Condition Photographic Documentation of Inventory Site DETAILED RATING OF INVENTORY SITES - GENERAL TIER 2 SITE DATA COLLECTION Tier 2 Data Procedures Geometrics and Traffic a) Traffic Survey Reports b) Actual Site Distance (ASD) c) Decision Site Distance (DSD) d) Percent Decision Site Distance (PDSD) Slope Information a) Slope Height b) Slope Elevations c) Slope Undercutting/Raveling d) Slope Jointing e) Rockfall Source Information f) Hydrologic Conditions g) Corrective Actions h) Catchment aa) Catchment Area Shape bb) Catchment Area Depth cc) Catchment Area Width dd) Foreslope Angle ee) Slope Face Angle ff) Remedial Effectiveness i) Additional Information TIER 3 & TIER 4 SITE DATA COLLECTION Slope Geological Conditions Number of Cut Slope Benches Number of Cut Slope Angles Cut Slope Angles Average Cut Slope Angle Cut Slope Angles Elevations Bench Elevations i

3 Bench Width Competent Bedding Incompetent Bedding Undercutting Information Joint Information Potential Rockfall Estimation Talus Accumulation Vegetation Additional Information Slope Hydrological Conditions Tier 3 & Tier 4 Testing Data Tier 3 & Tier 4 Office Data DATA COLLECTION ACKNOWLEDGEMENT RISK SCORING FOR INVENTORY SITES ROCKFALL INVENTORY SITE RISK SCORING DIFFERENTIAL WEATHERING DISCONTINUITY ROLE BLOCK SIZE/VOLUME OF ROCKFALL PER EVENT HYDROLOGIC CONDITIONS (SEEPS AND SPRINGS) ROCK SLOPE HEIGHT CATCHMENT/CONTAINMENT EXPOSURE RISK PERCENT DECISION SIGHT DISTANCE (PDSD) ACCIDENT HISTORY INSPECTION FREQUENCY LIST OF APPENDIXES APPENDIX A: GLOSSARY OF TERMS APPENDIX B: CRITERIA FOR EVALUATION OF CATCHMENT APPENDIX C: FIELD GEOLOGIC PARAMETERS APPENDIX D: PHOTO EXAMPLES OF TIERED SITES PHOTO EXAMPLES OF ROCKFALL RETENTION DEVICES APPENDIX E: GPS OUTLINE ii

4 LIST OF FIGURES FIGURE NUMBER TITLE OR DESCRIPTION PAGE NUMBER Rockfall Slope Inventory Rating Data Collection Process Rockfall Slope Inventory Process Screen Capture from ODOT Digital Photolog Rock Slope Evaluation Based on Road Type Example of Rock Slope vs. Inventory Site Example of Curved Rock Slope vs. Inventory Site Determined of Ramp BMP s Positions of an Inventory Site Potential of Rockfall to Impact Roadway Below the Roadway Examples of Cut Slopes Examples of Preliminary Rating (Tier 1) Photographs Relationship between slope height and geometric parameters Block Size Determinations a Block Size Before Falling b Block Size After Falling Rockfall Volume Determination Hydrologic Conditions Typical Types of Corrective Actions Catchment Area Shapes a Catchment Area b Hydraulic Control Ditch NOT as Catchment c Hydraulic Control Ditch as Catchment Catchment Area Configuration Example of Mine Openings Slope Angle Determination Recording Slope Angle along a Blast Hole Using a Pocket Transit Recording Slope Angle using a Pocket Transit and Non-ferric Clipboard Average Slope Calculation Example of Cut Slope Description Orthogonal Joint Set/Spacing Joint Infilling Example Rockfall Shapes Estimating Talus Accumulation Hydrologic Conditions Winter Conditions Hydrologic Conditions Spring Conditions. 64 iii

5 LIST OF TABLES TITLE NUMBER TITLE OR DESCRIPTION PAGE NUMBER Tier Type Based on Preliminary Rating Score A Preliminary Rating Criteria (Slopes Above Roadway) B Preliminary Rating Criteria (Slopes Below Roadway) Decision Sight Distance Typical Slope Values for Rock Cut Sections Rockfall Parameters Hydrological Prefixes Hydrological Conditions (Seeps and Springs) Rockfall History Risk Score Accident History Risk Score Re-Inspection Frequency LIST OF EXAMPLES EXAMPLE NUMBER TITLE OR DESCRIPTION PAGE NUMBER NFLID Coding Standard Sites with DMI Readings starting at SLM Sites with DMI Readings not starting at SLM BMP Position Data Preliminary Rating Score of an Inventory Site Determination of the Slope Configuration of the Inventory Site Percent Decision Sight Distance Calculating the Slope Height Weighted Average Calculation for Multi-Angled Cut Slopes Calculation of Bench Width and Elevation Slope Geological and Natural Conditions Collection of Joint Information Hydrological Conditions of Cut Slope and Natural Backslope Hydrological Conditions of Cut Slope and Natural Backslope Slake Durability Index Test Sample Collection iv

6 LIST OF EQUATIONS EQUATION NUMBER TITLE OR DESCRIPTION PAGE NUMBER 1 Percent Decision Sight Distance Vertical Height Calculation Foreslope Angle Calculation Slope Face Angle Calculation Average Slope Angle Calculation Exposure Risk v

7 Section 100 Introduction Rockfalls can constitute a major hazard along Ohio roadways, posing a risk to life, property, and traffic safety. As a result of rockfalls, maintenance problems are constantly occurring, resulting in a strain on the Ohio Department of Transportation (ODOT) funds and manpower. The following terms have been defined for use in this Manual: Rockfall: The down-slope gravitational movement of material that is comprised of at least 51 percent rock. Where, rock is defined as: Any material found along a slope that when freshly exposed has the characteristics of in-place bedrock. Bedrock includes, but not limited to, sandstone, siltstone, shale, limestone, dolomite, coal, claystone, and conglomerate. Rock Slope: Any slope, either natural or man-made, that has in-place bedrock exposed at the surface. Rockfall Event: A distinct period of time during which a single or multiple rock(s) and associated debris dislodges from a rock slope. This Manual was developed by ODOT, Office of Geotechnical Engineering (OGE) to inventory rock slopes, to identify potential hazardous rock slopes, to assess relative risk for those slopes, to determine degree of monitoring required, and to allow for actions to be taken to reduce, minimize, or eliminate the risk to the public s safety and to protect the highway system. This document is not a design manual. The intent of this Manual is to facilitate the creation of a statewide rockfall inventory process through the development of a statewide inventory procedure and the establishment of office and field methods. These methods should be used during the initial population of the inventory, inventory of new sites following the initial population, and for maintenance and monitoring of the sites. The data collection procedures are grouped into four (4) primary sections with subsections: Site Inventory and Preliminary Rating Tier 1 Site Rating Tier 2 Site Rating Tier 3 and Tier 4 Site Rating A rockfall inventory will be performed for the state highway system as noted in ODOT s policy on geohazards. This inventory will include all natural and man-made slopes with exposed bedrock. The field portion of the inventory shall be completed by a Field Team(s). For safety concerns, a Field Team should consist of a minimum of two members. For a multi-discipline approach, the Field Team shall consist of a geologist and either an engineering geologist or geotechnical engineer. The optimum time for the performance of 1

8 the field work along slopes that have high relief and/or are highly vegetated is October through April. However, it should be noted that snow may also limit field activities in December through February. Field activities may be suspended during periods of inclement weather as directed by ODOT. Slopes that have low relief and/or low to moderate vegetation may be evaluated year round. Within this Manual, slopes which are being inventoried will generally be referred to as a rock slope. All rock slopes shall receive a Preliminary Rating based on basic site characteristics. The Preliminary Rating will also segregate the lower priority sites from the groups that will receive detailed data collection efforts. This Manual will outline a tiered data collection methodology which will allow rock slopes within Ohio to be rated for relative rockfall risk to the public and Ohio s highway system. The data collected from each site will be incorporated into an Enterprise Database and integrated into a GIS system. All information collected by personnel in the field or office should be presented in standard database format, Excel spreadsheets, and GIS ArcView file(s) utilizing ODOT s standardized file naming conventions. The data collected from the inventory process will be stored within the Geologic Hazard Management System (GHMS) and other related components of the ODOT GeoMS. Appendix A presents a Glossary of Terms that should be used in association with this Manual. Section 200 Rock Slope Inventory and Data Collection 201 Purpose and General Process The inventory will consist of identifying and locating Inventory Sites within the rock slopes situated along Ohio s highway system. Generally, this inventory will be concerned with rock slopes located above the roadway, unless a rockfall event below the road could result in adverse impacts to the highway system. As part of the rock slope inventory, a Preliminary Rating of each Inventory Site will be performed on each site. The Preliminary Rating will provide guidance as to what level of data collection (Detailed Rating) is required. The Preliminary Rating will be completed by the Field Team(s) by visually evaluating two criteria for each Inventory Site. These criteria are: 1) the potential of a rockfall occurrence from the slope and 2) if a rockfall was to occur, the potential of the rock to reach the traffic lane. This evaluation will be based upon best professional judgment and past experience of the Field Team(s). A rating of Low, Moderate, High, or Very High will be used for each criteria with an associated numerical value assigned. Section Inventory Site Determination discusses in detail how to select an Inventory Site and perform the Preliminary Rating. For those sites where a Detailed Rating is not required, the slope will be listed as a Tier 1 site, or non-rated within the GHMS, with assigned data parameters required during the 2

9 field data collection. The following Tiers are considered as Rated Sites within the GHMS. A detailed explanation of the procedures will be presented in the subsequent sections with a brief description of each Tiered Rating as follows: A Tier 1, or non-rated, site will consist of rock slopes that have a low or moderate potential of rockfall occurring from the slope, and a low or moderate potential of any rockfall reaching the travel lane of the roadway. It should be noted that if both potentials are moderate to very high then the site is not a Tier 1 site, but a rated site and will require Detailed Rating data collection. Tier 2 sites will consist of sites where the potential of a rockfall occurrence is moderate to high, and the potential of the rockfall reaching the traffic lane is moderate. Tier 3 and Tier 4 sites are sites that the potential of a rockfall occurrence is high to very high and the potential of the rockfall reaching the traffic lane is high to very high. The difference between a Tier 3 and Tier 4 site is that a Tier 4 site poses an immediate threat to the safety of the public and/or the roadway. The methodology for data collection is outlined in the following sections: Section 202 Site Inventory and Preliminary Rating Section 203 Tier 1 Data Collection Section 205 Tier 2 Data Collection Section 206 Tier 3 and Tier 4 Data Collection Each section will outline the office and field procedures to collect all the required data for the site. All sites will require the Tier 1 data collection, which is the minimum required data inputs, for the Rockfall Slope Inventory. Sites that are categorized as a Tier 2 site from the Preliminary Rating will require Tier 1 augmented with Tier 2 data collection. For sites that are categorized as either Tier 3 or Tier 4 sites from the Preliminary Rating will require all levels (Tier 1, 2, 3 & Tier 4) of data collection. The Tiered sites are also referenced as Non-Rated for Tier 1 locations or Rated if they are a Tier 2, 3, or 4 location. If a debris fragment greater than 6 inches in any dimension, or debris greater than one cubic foot in total volume, occupies the shoulder, travel lane(s) or median, the District Geotechnical Engineer (DGE) and the Office of Geotechnical Engineering (OGE) shall be notified within one week and the site shall be re-evaluated within one month of the 3

10 event. If an Inventory Site is determined to be a Tier 4 designation, the DGE and OGE shall be notified within 24 hours from completion of the evaluation. Figure is a generalized flow chart outlining the data collection process for the Rockfall Inventory. Figure ROCKFALL SLOPE INVENTORY RATING DATA COLLECTION PROCESS Rock Slope Identification and Inventory Site Identification Preliminary Rating Completed (Refer to Section 202 Site Inventory and Preliminary Rating) Notify DGE & OGE Immediately if Tier 4 Site Identified Tier 1 Data Collection (Refer to Section 203 Tier 1 Site Data Collection) Tier 1 Site: Data Collection Completed Tier 2 Data Collection (Refer to Section 205 Tier 2 Site Data Collection) Tier 2 Site: Data Collection Completed Tier 3 & Tier 4 Data Collection (Refer to Section 206 Tier3 & 4 Data Collection) Tier 3 Site: Data Collection Completed Tier 4 Site: Data Collection Completed Inventory Site Routine Monitoring Populate Database with Inventory Site Figure is a generalized Organization Chart for the initial population of the Rockfall Inventory and Slope Rating System. 4

11 Figure ROCKFALL SLOPE INVENTORY PROCESS ODOT Project Manager Training QA/QC Progress Reports Scheduling Field Team(s) Preliminary Office Data Collection Site Inventory & Preliminary Rating Tier 1 Tier 2, 3, or 4 Database Input Detailed Field Rating Detailed Office Data Collection Tier 3 & 4 Sampling ODOT Testing Consultant Testing 5

12 202 SITE INVENTORY AND PRELIMINARY RATING General The Project Manager and Field Team(s) will begin their work based upon the selection of the counties and routes as designated by OGE and District personnel. Study routes will encompass Interstate Routes, US Routes, and State Routes throughout the state including routes within municipalities. The Project Manager and Field Team(s) will evaluate and select the most efficient travel pattern or routes for completion of the fieldwork prior to starting the field data collection. Priority selection of counties will be based on National Highway System (NHS) Routes (Interstate Routes, US Routes, and designated State Routes), then the remaining State Routes (non-arterial) within those counties. Routes that have had historical rockfall events should be completed before routes that do not have a historical record of rockfall Office Procedures Prior to commencement of the field work, the Project Manager and Field Team(s) should have an idea as to the location of rock slopes that have a rockfall potential in relation to Ohio s highways. The following sections outline the general office procedures for the development of a work plan for site investigations ODOT Interview(s) Prior to commencing the fieldwork, the Field Team(s) shall contact and schedule interviews with the ODOT DGE/Geologist for each respective District, the ODOT County/Transportation Manager(s) for each respective county, and any other applicable ODOT personnel (e.g. highway workers) who are familiar with the rockfall maintenance for the selected area. In addition, interviews may be conducted with county and/or city engineers or maintenance crews for locations where personnel outside of ODOT perform the roadway maintenance or have additional knowledge of the roadway. The Field Team(s) will interview all applicable ODOT personnel as to locations of rock slopes within their county and/or District. Additionally, the interviews should reveal where rockfall is actively occurring or has been a historical problem. Information from these interviews should include, but is not limited to: 6

13 Straight Line Mile (SLM) location(s) of natural or cut slope(s) with exposed bedrock SLM locations of rockfall and frequency Date and amount (size and volume) of rockfall Length and width, referenced to the roadway, where rockfall debris has accumulated Accidents resulting from rockfall including date, damage to State or private property, injuries, and/or fatalities Scheduled maintenance of rock slope(s) and associated ditch line, including but not limited to, ditch cleaning of rockfall debris, bench cleaning along cut slopes, rock removal from shoulder or roadway, etc. Any rockfall remediation work performed in the past A Personnel Interview Data Form, included in Appendix G Field Forms, should be completed for each person or group interviewed recording the information collected. The Interviewee data will be stored in the GHMS within Part A: Interview Info. If paper forms are being utilized then the interviewee data will be recorded on the Rockfall Site Inventory Site Field Form (Rockfall Form) in Section B: ODOT INTERVIEWS. Additionally, this information will be necessary to complete Section I: REMEDIAL WORK OBSERVATIONS to identify if, when, and/or where corrective actions have been completed Digital Photolog The Project Manager and/or Field Team(s) may review available Digital Photolog(s) via the ODOT Pathweb System for each selected site or route. The Digital Photolog System (Pathweb) was updated in 2011 to allow the user to view the roadway, including a limited view of the side of the roadway, prior to commencing their fieldwork. Digital Photolog(s) are available from ODOT Office of Technical Services (OTS) and is not available through the internet. The digital photolog is a digital recording created by driving a route with a digital video recording device mounted on the front, back and sides of the vehicle. A digital image of the roadway and shoulder is collected at an interval of every mile (200 shots per mile). As part of the photolog a Log-Mileage, based on a digital measurement instrument (DMI), and a GPS recording of latitude and longitude are presented. The GPS readings are drift corrected geospatial data. From the Log Mileage information, the Field Team(s) can determine the approximate mile marker where the anticipated rock slope(s) is located. Additionally, a GPS map will show spatially the approximate location of the screen shots. Figure shows a screen capture from the photolog application. 7

14 Camera Views County Section Coordinates Route Figure SCREEN CAPTURE FROM ODOT PATHWEB Other Photographic Alternatives Additionally, the Field Team(s) can review available aerial stereopairs, high resolution digital aerial photos, and orthophoto quadrangle sheets or Google Earth Street View in an attempt to refine the rock slope locations that may be a source of rockfall. Aerial images, including stereopairs and obliques, orthophoto quadrangle sheets (DOQ), USGS 7.5 minute topographic quadrangle sheet (topo), and photogrammetric maps are available from ODOT Office of Cadd and Mapping Services. Additionally, the DOQ s and topos can be obtained from the United States Geological Survey Geological Reference General geological data shall be collected for each county prior to commencement of the fieldwork. This data can be collected from the Geologic Map of Ohio 8

15 and/or the County Quadrangle Bedrock Geology Map for the respective USGS Quadrangle. A rock description for each Geologic Map Unit associated with the County Quadrangle Bedrock Geology Map is produced by the Ohio Department of Natural Resources (ODNR) Geological Survey. The Geologic System/Period, Group(s)/Formation(s), and primary rock types should be identified. Many of these maps and others (e.g. bedrock geology, bedrock structure, bedrock topography) are available as electronic files for GIS applications. Additionally, the study area(s) should be evaluated for the potential presence of known surface and underground mining, either abandoned or active. Mining activities, both current and past, can be obtained from ODNR or ODOT as GIS layers. This data will be recorded in the GHMS in Part C: Geological, additional information tab and on the Rockfall Form in Section I: GENERAL GEOLOGIC DESCRIPTION Field Procedures Inventory Site Determination For each route, it is preferred that the Field Team begin at County Log Mile (CLM) 0.00, which will have a corresponding Straight Line Mile (SLM) However, any known SLM referenced point can be utilized as a beginning point. To begin, the DMI should be adjusted to zero at the county line or beginning of the route. If starting at a known referenced point (e.g. structure or interchange) adjust the DMI reading to the corresponding SLM. If the Field Team has to stop for the day, or the need to re-zero the DMI is required, each structure has a SLM recorded at its right side of the rear abutment in the cardinal direction, and a SLM is available for each center point of roadway intersections. All mile marker records for the rockfall inventory should be referenced to SLMs. The DMI records will be in a True Log Mile format and will need to be adjusted to the corresponding SLM. Straight Line diagrams referencing the SLM can be obtained from OTS. Using a zeroed DMI reading (from a reference point), proceed in the cardinal or non-cardinal direction, until a rock slope is encountered. The Field Team should evaluate each rock slope encountered. For bifurcated highways with rock slopes encountered on both sides of the travel lane, the rock slopes for both sides of the travel direction should be evaluated at the same time. For divided highway, all rock slopes along the right side of the roadway should be evaluated. Then, all the rock slopes on the opposite side of the roadway should be evaluated while driving in the opposite direction. For non-divided highways rock slopes can be evaluated on both sides of the roadway at the same time. Care must be taken in correcting for the Beginning Mile Point (BMP) along the opposite rock face. Figure provides examples of how the rock slope shall be evaluated based upon roadway type. 9

16 Evaluate Both Evaluate Only Evaluate Both Evaluate Only Non-Cardinal Direction Cardinal Direction Non-Cardinal Direction Cardinal Direction Bifurcated Roadway Evaluate Only Evaluate Only Evaluate Only Evaluate Only Non-Cardinal Direction Cardinal Direction Non-Cardinal Direction Cardinal Direction Divided Highway Evaluate Both Evaluate Both Non-Cardinal Direction Cardinal Direction Non-Cardinal Direction Cardinal Direction Non-divided Highway Figure ROCK SLOPE EVALUATION BASED ON ROAD TYPE Each rock slope location can be evaluated as a single or multiple Inventory Site(s). An Inventory Site is defined as: any continuous roadway section where a rock slope has the same characteristics. A minimum slope height of 10-feet is required to be an Inventory Site, unless the Field Team determines that a slope with a height less than 10 feet poses a danger to safety of the traveling public. These characteristics shall be based upon: 10

17 limits of the exposed rock face natural breaks in the cut face or natural backslope (e.g. natural drainage features, but not man-made drainage features) changes in slope orientation relative to the roadway (e.g. roadway curves around the nose of a hillside that contains a continuous cut section) changes in the slope orientation relative to the regional joint patterns changes in the cut face angle(s) changes in the quality of the bedrock mass Additionally, the following guidelines should be followed in establishing Inventory Sites: 1. For cut slopes that contain intermittent rock exposures through vegetation, but was obviously constructed as a single continuous cut, the site should be inventoried as a single Inventory Site. 2. A series of small cuts should not be combined into a single Inventory Site; because, if a problem arises from just one of the cuts, corrective actions will only apply to the single cut in question, not all of the cuts. 3. The ends of the cuts should not be split out into short sites based only on the change in height of the cut slope. If work is to be performed on a large site typically the ends will be included within the project. 4. When a cut height is disrupted due to the presence of a structure abutment with similar characteristics on either side of the abutment, the slope should not be broken into two sites, unless the slope characteristics change. 5. Prior to extending an Inventory Site to a distance of more than onehalf mile (+/-), contact the District Geotechnical Engineer (DGE) or the Office of Geotechnical Engineering (OGE). In no case should an Inventory Site extend more than one mile (+/-) or cross county lines. A new Inventory Site should be created at a county border. Figures and show examples of Inventory Sites relative to a rock slope and Figure shows an example for Ramp BMP s a) Site Determination for Ramps Sites located on ramps will be referenced to the SLM of the mainline. The selected mainline for the SLM referencing will use the following conventions: Interstates over US Routes and State Routes US Routes over State Routes If there are two Interstates, US Routes or State Routes, the lower numbered route will be the referenced route 11

18 Inventory Site #8 N Inventory Site #7 4 Inventory Site #6 EXTENT OF ROCK SLOPE 10,032 ft (1.9 miles) Natural Drainage No Rock Slope Natural Drainage with Rock Slope 3 Inventory Site #5 Inventory Site #4 Rock Slope Natural Drainage No Rock Slope 2 Inventory Site #3 Inventory Site #2 1 Inventory Site #1 Figure EXAMPLE OF ROCK SLOPE VS. INVENTORY SITE Comments: The total extent of the rock slope is approximately 1.9 miles, or 10,032 feet. The 10,032 feet of rock slope can be divided into 4 basic segments based on topography and major local drainage indicated in the circles. From these basic segments a total of 8 Inventory Sites should be evaluated based upon minor drainage features, change of slope face orientation relative to the roadway, change in slope face orientation relative to the regional joint patterns, and change in cut slope angle(s). 12

19 Approximate Roadway Centerline 4 Top of Cut N Inventory Site Figure EXAMPLE OF CURVED ROCK SLOPE VS. INVENTORY SITE N Approximate Ramp BMP Location Traffic Flow of Ramp Figure DETERMINATION OF RAMP BMP s 13

20 Preliminary Rating of Inventory Site The Preliminary Rating of a site should be completed for all Inventory Sites as the first step to populate the rockfall inventory. The Preliminary Rating is basically a two part process: 1) Inventory Site Location 2) Preliminary Rating Score a) Inventory Site Location For each rockfall Inventory Site, location data will need to be recorded to identifying the site s specific location. The following data is required to identify the Inventory Site Location. This data is recorded in Part A: Site Location of the GHMS or within Section A: PROJECT LOCATION AND INFORMATION of the Rockfall Form. The following data is included under the Basic Information tab within the GHMS Section Site Location. District County Route System Route Number (5-digit ODOT designated route number) Jurisdiction Code (C-County, H-Turnpike Commission, M-Municipal, S-State, T-Township) Slope orientation (in degrees from north (azimuth coordinate), relative to the BMP, running parallel to the direction of traffic flow) Measured length of the Inventory Sites (in feet) along roadway Beginning Mileage Point (BMP) (as the SLM value determined from the DMI reading [Note that the BMP is the lowest SLM value for the site]) Ending Mileage Point (EMP) (as a SLM value determined based upon the Inventory Site length and BMP) Record if the site is located along the roadway in the cardinal direction (Yes = northbound or eastbound, No = southbound or westbound) Horizontal Position of the Rock Slope (Right or Left relative to cardinal mainline direction or to driving direction for ramps) Driving direction: (North, South, East, West) Vertical Position (Above, Below or Both) USGS Quadrangle Name 14

21 The Network Linear Feature Identification Code (NLFID Code) will be auto generated for the location (update button). The NFLID designation is a tracking code consisting of: Jurisdiction Code County Classification Code Route Number Default code to complete the NLFID Code (**C) Example presents the format for the NFLID Code Optional Information concerning the site consists of: Classification of roadway Hazard width perpendicular to the road (from toe of cut) Distance from Toe of cut to shoulder EXAMPLE : NLFID Coding Standard NLFID CODE - STUSUS00250**C S TUS US **C Where: A B C D E A is the Jurisdiction Code B is the County Code C is the Classification Code D is the Route Number E is the default code The following data is included under the Roadway Information tab within the GHMS Section Site Location: Position Relative to the Roadway (Mainline, On-ramp, Off-ramp) Pavement Type Median 15

22 Optional Information concerning the site consists of: Classification of roadway Hazard width perpendicular to the road (from toe of cut) Distance from Toe of cut to shoulder The following data is included under the GPS Information tab within the GHMS: Beginning Latitude Beginning Longitude BMP of Inventory Site Beginning Elevation Offset Distance, in feet, and Bearing, in degrees from north (azimuth coordinate), if the positional data is not able to be collected at the exact position of the BMP location For Rockfall Inventory Sites, only the BMP coordinates will required. However, if field personnel have a strong GPS signal, additional points can be collected and coordinates recorded for the Centroid and EMP locations. The beginning and end of the Inventory Site should be indicated in the field by placing a minimum 18-inch long white line perpendicular to the roadway made with surveyor s paint at either end of the site along the edge of the pavement. The BMP should be indicated with a B, and the EMP should be indicated with an E. Note: it can be helpful for large sites, if while measuring the Inventory Site length, place tick marks along the roadway shoulder at regular intervals (say 100 or 200 feet) to use in locating features aa) Beginning Mile Point (BMP) The BMP shall be determined based upon the DMI reading recorded at the beginning point of the Inventory Site. The BMP shall always be the lowest SLM point of the Inventory Site. If the DMI reading at the BMP was started at SLM 0.00 then the BMP is the adjusted DMI reading. However, if the DMI reading recorded at the BMP was started at a location other than SLM 0.00, the BMP needs to be calculated by adding the starting point SLM and the adjusted DMI reading. The adjusted DMI reading is the true log mile reading adjusted for the station equations to calculate the SLM. Record the BMP value to the nearest 0.01 miles. Place a PK nail into the paved shoulder or the roadway to indicate the BMP. If no paved shoulder is present, place the PK nail into the white edge line. The PK nail should be driven either flush with, or below, the top of pavement. 16

23 bb) Inventory Site Length The length of the Inventory Site is a direct measurement between the BMP and the EMP. Generally, this measurement is made with either a measuring tape, measuring wheel, or a laser range finder. Record the Inventory Site Length to the nearest foot cc) Ending Mile Point (EMP) For mainline sections, the EMP can be calculated based upon the length of the Inventory Site divided by 5280 ft/mile then added to the BMP, and/or recorded utilizing the adjusted DMI reading as outlined in Section aa) Beginning Mile Point (BMP). The EMP should be determined by establishing the offset location to its referenced mainline then calculating this offset point utilizing either the DMI or other measuring device. Record the EMP value to the nearest 0.01 miles. EXAMPLE : Sites with DMI Readings starting at SLM 0.00: Inventory Site Attribute SLM DMI Reading from SLM 0.00 = 2.91 Beginning SLM (BMP) = 2.91 Length of Site = 1850 ft 1850ft 5280ft/mile = 0.35 mile Ending SLM (EMP) = 3.26 BMP mile 17

24 EXAMPLE : Sites with DMI Readings not starting at SLM 0.00: Inventory Site Attribute SLM SLM at Starting Intersection = DMI Reading from Intersection = 2.91 Beginning SLM (BMP) = Length of Site = 1850 ft 1850ft 5280ft/mile = 0.35 mile Ending SLM (EMP) BMP mile = For ramps where the BMP and/or the EMP is not visible from the mainline then that value does not need to be recorded dd) BMP Position Record the BMP position as a GPS point at the right shoulder of the BMP. The BMP position shall include the latitude, longitude, and elevation and be determined using a Trimble GPS unit, or equivalent or better, as a point in decimal degrees to six (6) digits to the right of the decimal. GPS guidelines for data collection are presented in Appendix E. If a GPS reading cannot be taken along the shoulder of the roadway at the BMP of the Inventory Site due to poor signal, or physical obstruction, use an offset reference point which has good access and an adequate GPS signal. After recording the GPS coordinates at the offset location, collect and record a bearing, the offset distance from the reference point to the BMP, and change in ground surface elevation to the shoulder location at the Inventory Site BMP position. The bearing value should be obtained in degrees from north (azimuth coordinate), and the offset distance and change in ground height need to be recorded as a physical measurement to the nearest foot. The raw data collected at the site will be recorded as an.ssf file. A separate.cor file should be created for each Inventory Site upon completion of the post processing of the raw data. Both the.ssf and.cor files should be saved. EXAMPLE : BMP Position Data: BMP Latitude = BMP Longitude = BMP Elevation = 765 ft Offset Bearing = 127º Offset Distance = 185 ft Change in Elevation = 7 ft 18

25 Figure is a generalized diagram indicating how to determine the positions of the rockfall Inventory Site. Top of Natural Backslope Rockfall Zone Rock outcropping in Natural Backslope DRAINAGE FEATURE DRAINAGE FEATURE Top of Rock Cut BMP EMP Beginning of Inventory Site MP 2.91 BMP Position Latitude: Longitude: Elev.: 765 ft 1851 Ft. Inventory Site Length Ending of Inventory Site MP 3.26 Figure POSITIONS OF AN INVENTORY SITE Preliminary Rating Scoring There are two components of the preliminary rating. The first part is the determination of the probability of a rockfall event using best professional judgment. Rockfall debris can be generated from either the cut slope or from the natural backslope. Second, evaluate the potential of a rock or debris impacting the roadway. Typically the impact to the roadway is a result of rockfall debris reaching the traffic lane. Traffic Lane is defined for use in this Manual as: The inside edge of the right vehicular lane in a given travel direction or the white edge line. Potentials of Very High, High, Moderate, or Low are used, with numerical values (10, 8, 4, 1, respectively) assigned for each potential. The numerical value for the potential of rockfall occurrence is added to the numerical value for the potential of the rockfall to impact the travel lane to determine the 19

26 Preliminary Rating Score. Preliminary Rating Score values may range between 2 and 20 points which is then used to determine the level of data collection, or Tier, required for the Inventory Site. For locations where the Preliminary Rating Scores fall between 2 and 5 points, the Inventory Site is considered a Tier 1 site. No Detailed Rating data collection is required for Tier 1 sites. For Preliminary Rating Scores over 5 points, the Inventory Site is either a Tier 2, Tier 3, or Tier 4 site requiring a Detailed Rating which will result in additional data collection. Table outlines the Preliminary Rating Score breakdown for each Tier. TABLE Tier Type Based on Preliminary Rating Score Preliminary Rating Tier Type Score Action 2 to 5 8 to to to 20 TIER 1 SITE No Detailed Rating Needed TIER 2 SITE Detailed Rating Needed TIER 3 SITE Detailed Rating Needed TIER 4 SITE Detailed Rating Needed For rockfall sources located at such a distance that any rockfall debris will not reach the travel lane, these areas do not need to be inventoried. Additionally, if the slope contains an area where the catchment (ditch or barrier) does not contain sufficient storage between either the back of the barrier or the white edge line to contain the anticipated volume of rock and debris that could be dislodged in an event, the Potential of Rockfall Reaching the Roadway needs to be shifted to Very High. The Catchment Storage is defined as: the calculated volume based on the width by depth of the catchment area based on the length of the catchment relative to the area where rockfall could occur. The calculated volume should take in account any barrier height along the edge of the catchment. Table outlines general criteria for each of the category utilized in the Preliminary Rating. 20

27 TABLE A - PRELIMINARY RATING CRITERIA (Slopes Above Roadway) Category LOW (1 POINT) MODERATE (4 POINTS) HIGH (8 POINTS) VERY HIGH (10 POINTS) No fresh exposures Few to some fresh exposures Some to many fresh exposures Many fresh exposures No adverse joint patterns Moderate weathering of rock strata within a cut section Observed minor stability issues within slope face Stability issues within slope face Potential of Rockfall Occurrence No undercutting evident Some jointing present Minor undercutting is present Occasional cleaning required of catchment area Weathered rock strata within a cut section Significant jointing, or adverse jointing present Significant undercutting present Annual cleaning required of catchment area Minor amounts of rockfall debris evident within catchment area or evidence of recent cleaning of the catchment area Highly weathered to decomposed rock strata within a cut section Major adverse joint, or intersecting jointing present Severe undercutting present Significant amounts of debris is evident within the catchment area, especially along the shoulder Frequent cleaning required of catchment area Potential of Rockfall to Impact Roadway The distance from the slope face to the travel lane is greater than the anticipated roll out distance ** The distance from the slope face to the travel lane is greater than the impact zone, but less than the rollout zone ** The distance from the slope face to the travel lane is within the impact zone ** Slope is within three feet of roadway OR Rockfall or evidence of rockfall within the travel lane, median, or opposite shoulder is present OR OR OR OR An appropriately sized barrier exists between the slope face and the roadway Rockfall or evidence of rockfall is present along the edge of the shoulder Rockfall or evidence of rockfall within the shoulder is present Documentation of rockfall debris reaching the roadway including accidents or injury ** Impact zone and rollout width based upon the Appendix B guidelines. These guidelines provide distances based upon the cut slope angle and height within a rock cut section. Generalized tables of distances are provided in Appendix B. 21

28 Table B - PRELIMINARY RATING CRITERIA (Slopes Below Roadway) Category LOW (1 POINT) MODERATE (4 POINTS) HIGH (8 POINTS) VERY HIGH (10 POINTS) No fresh exposures Few to some fresh exposures Some to many fresh exposures Many fresh exposures No adverse joint patterns Moderate weathering of rock strata within a cut section. Observed minor stability issues within slope face Stability issues within slope face Potential of Rockfall Occurrence No undercutting evident Some jointing present Minor undercutting is present Occasional cleaning required of catchment area Weathered rock strata within a cut section Significant jointing, or adverse jointing present Significant undercutting present Annual cleaning required of catchment area Minor amounts of rockfall debris evident within catchment area or evidence of recent cleaning of the catchment area Highly weathered to decomposed rock strata within a cut section Major adverse joint, or intersecting jointing present Severe undercutting present Significant amounts of debris is evident within the catchment area, especially along the shoulder Frequent cleaning required of catchment area Potential of Rockfall to Impact Roadway *** Failure within slope will not affect roadway Failure within slope will affect Right of Way, but not shoulder or roadway Failure within slope will affect shoulder, but not roadway Failure within slope will affect roadway *** Refer to Figure POTENTIAL OF ROCKFALL TO IMPACT ROADWAY - BELOW THE ROADWAY for clarification. Further discussions within this Manual will be limited to rockfall impacting the roadway from sources above the roadway. The Preliminary Rating Data is reported within the GHMS in Part A: Preliminary Rating tab. 22

29 Figure POTENITAL OF ROCKFALL TO IMPACT ROADWAY BELOW THE ROADWAY Edge of Road Edge of Shoulder Edge of Road Edge of Shoulder Right-of-Way Right-of-Way Low Risk of Rockfall to Impact the Roadway Moderate Risk of Rockfall to Impact the Roadway Edge of Road Edge of Shoulder Right-of-Way Edge of Road Edge of Shoulder Right-of-Way High Risk of Rockfall to Impact the Roadway Very High Risk of Rockfall to Impact the Roadway 23

30 EXAMPLE : Preliminary Rating Score of an Inventory Site: A site has a high potential of rockfall occurrence due to the presence of debris within the ditch along the road shoulder and a moderate potential of rockfall reaching the travel lane due to the distance from the rock face to the shoulder is slightly less than the rollout zone for the slope height. Potential of a Rockfall Occurrence PRELIMINARY RATING Potential of Rockfall Impacting the Traffic Lane Very High (10) High (8) Moderate (4) Low (1) Very High (10) High (8) Moderate (4) Low (1) High Potential of Rockfall Occurrence = 8 points Moderate Potential of Rockfall Reaching the Traffic Lane = 4 points Total Preliminary Rating Score for Inventory Site = (8 + 4) = 12 points Therefore: Preliminary Rating Tiered Scoring Preliminary Rating Scale 2 to 5 8 to to 16 TIER Type Action TIER 1 SITE No Detailed Rating Needed TIER 2 SITE Detailed Rating Needed TIER 3 SITE Detailed Rating Needed TIER 4 SITE 18 to 20 Detailed Rating Needed Comments: Based on the Preliminary Rating Score of 12, this site is considered a Tier 3 Site requiring a detailed site rating including the collection of all Tier 1 and Tier 2 data. 24

31 203 TIER 1 DATA COLLECTION Typically, the field data collection process will be completed within ODOT right-of-way. However, occasionally, the slope will extend onto private property, especially for natural backslopes above the cut slope. When this occurs the Field Team should make all possible attempts to contact the property owner to obtain permission prior to entry onto the property Field Procedures For all Inventory Sites, rated and non-rated, the Tier 1 Field Data must be completed. This data will be recorded within Part A of the GHMS or recorded on the Rockfall Form in Section C: TIER 1 FIELD DATA Slope Configuration Determine the slope configuration of the cut slope. Within the GHMS this data is reported in Part A: General Information, Basic Slope Information tab. Figure shows examples of different slope configurations, and the following are descriptions of each criteria: Single-angle Slope (SA): Slope that contains the same general slope geometry from the road to the crest of the slope Multi-angle Slope (MA): Slope that contains at least two slope angles from the road to the crest of the slope Single-angle Benched Slope (SB): Slope that contains the same general slope angles and a relatively flat bench or break between the angles from the road to the crest of the slope Multi-angle Benched Slope (MB): Slope that contains at least 2 slope angles and a relatively flat bench or break between any of the slope angles from the road to the crest of the slope EXAMPLE : Determination of the Slope Configuration of the Inventory Site Slope Configuration: SA MA SB MB Where: SA is for Single-angle Slopes MA is for Multi-angle Slopes SB is for Benched Slope Single-angled MB is for Benched Slope Multi-angled 25

32 Single-angle Slope (SA) Single-angle Benched Slope (SB) Multi-angle Slope (MA) Multi-angle Benched Slope (MB) Figure EXAMPLES OF CUT SLOPES 26

33 Slope Condition Record general comments about the rock slope within the Inventory Site. Comments that can be recorded can be the amount of vegetation along the slope, talus buildup, if any, weathering of the exposed rock strata, general performance of the slope, etc. It should be noted that if the site will have a detailed rating performed, these comments can be very brief, since the slope will be discussed in detail during the Detailed Data Collection. Within the GHMS in Part A: General Information, Slope Condition several field are available for the general description of the slope. Vegetation coverage: with percentage of slope coverage by shrub, trees, grass, and other (if other is used then a text description is required). Weathering condition: None, Slight, Moderate, Complete Talus buildup: Yes, No General slope performance: stable, potentially instable, unstable Exposed rock: click all that apply Photographic Documentation of Inventory Site Upon completion of the Tier 1 Field Data measurements, take representative pictures of the Inventory Site. For Tier 1 sites three pictures should be taken. One picture should be taken at an acute angle from each end (BMP and EMP) of the site, and one picture should be taken perpendicular to the maximum slope height (MHT) of the Inventory Site. Within the GHMS, these pictures should be uploaded in Part A: General Information, Pic/Doc Information tab. At the tab heading a count of the number of items located in the directory are present. It should be noted that additional pictures may be required for Rated Sites (Tier 2, Tier 3, or Tier 4) data collection. The requirements of these pictures are presented within each of these respective sections. The proper naming convention for the labeling of the pictures is presented within Appendix D. Appendix D presents examples, including photographs and discussions, of Tier 1, Tier 2, Tier 3, and Tier 4 sites. 27

34 BMP EMP End Pictures of Rockfall Inventory Site (SCI looking east and west, respectively) MHT Picture of the Maximum Height of the Rock Slope Figure EXAMPLES OF PRELIMINARY RATING (TIER 1) PHOTOGRAPHS 204 Detailed Rating of Inventory Sites - General For sites where rockfall poses a potential risk to traffic (Preliminary Rating Score >5), the site is considered a Rated Site and a detailed site rating needs to be performed. The amount of information required for the Detailed Data Collection is based upon the Preliminary Rating Score completed in Section Site Inventory and Preliminary Rating. For sites that score as Tier 2 sites, collect the information required in Section 205 Tier 2 Site Data Collection. For sites that score as either a Tier 3 or Tier 4 site, complete the Tier 2 data collection in addition to Section Tier 3 and Tier 4 Data Collection. Prior to commencement of the Detailed Data Collection, the Field Team should observe the cut slope and natural back slope and evaluate the following: 28

35 Limits of the Inventory Site (BMP, EMP) Location of all potential sources of rockfall Number of slope angles Number of benches that comprise the rockfall section Location of any joint/fracture set(s) (orthogonal or stress relief) Groundwater Surface water flow or evidence of surface water flow General condition of the cut slope (e.g. where undercutting may be occurring, talus buildup) Any mine opening (sealed or non-sealed), coal seams, clay seam, or mineable mineral seam visually present Evidence of possible slope instability within the soil mass above the rock cut The Field Team should then determine the most efficient and safe way to collect the field data from the rock slope. All slope angles and benches should be numbered sequentially from the bottom of the rock slope (ditch line) to the top of the rock slope independent of how the data was collected. If the Field Team feels that no safe way of collecting the field data is evident within an Inventory Site contact OGE. If the Field Team feels that the slope possess an immediate threat to the welfare of the traffic on the roadway, contact the respective ODOT County/Transportation Manager, the DGE, and OGE within 24-hours to inform them of the situation to provide appropriate traffic control measures. If necessary, ODOT will arrange for traffic control measures such as lane closures or temporary barriers. 205 TIER 2 SITE DATA COLLECTION Tier 2 Data Procedures Upon completion of the Preliminary Rating, sites which are Rated (Tier 2, Tier 3, or Tier 4) need to have additional information collected. The following sections outline the detailed breakdown on the methodology for the field and office data collection. For low height rock slopes, where both the cut slope and the natural backslope are observable and all features are visible from the roadway, the data may be collected from the roadway. Slope angles can be collected from the roadway with a clinometer or profiler; otherwise, the angles should be collected as a direct measurement from the slope. If the entire slope is not observable from the road surface, the slope face shall be inspected and evaluated by either climbing the face or repelling from the top. The preferred method of data collection is by direct measurements taken from the slope face or the use of a profiler. Generally, the best way to complete direct measurements from the slope face is by performing horizontal and vertical line survey(s). 29

36 Geometrics and Traffic The following are the office and field procedures for completion of TIER 2 - GEOMETRICS AND TRAFFIC DATA. For the respective data locations within the GHMS, refer to the individual item. The majority of the geometric and traffic data within this section can be obtained through the ODOT Transportation Information Management System (TIMS) or other resources of the Office of Technical Services. However, it should be noted that these data fields can be collected through physical observation or measurements a) Traffic Survey Reports Record the Average Daily Traffic (ADT), Average Vehicular Traffic, including Type A commercial vehicles, (AVT), and Average Truck Traffic (ATT) values, for the section of roadway which contains the Inventory Site. These values can be obtained from the Traffic Survey Reports which can be accessed from the web. The traffic reports allow the user to select a report based upon county and year that the survey was completed. A complete report for each selected county is then provided that includes all state highways. Each Route is subdivided based on straight line miles within a Traffic Section, which gives a general description of where the data was recorded, section length in miles, and columns for passenger & type A commercial vehicles, type B & C commercial vehicles, and total vehicular traffic. The passenger & A commercial vehicle column refers to the AVT value, B & C commercial traffic column refers to the ATT value, and the total vehicular traffic column refers to the ADT. The most recent survey should be utilized to determine the individual counts. This data will be recorded within the GHMS in Part B: Traffic Information b) Actual Site Distance (ASD) The Actual Site Distance (ASD) is the shortest distance along a roadway over which a six inch object is continuously visible to a driver, and is a physical measurement based on the following method: Place a 6-inch high traffic cone or hard hat near the edge of the roadway within the rockfall section. From that point move away from the object until it is no longer visible from a height of 3.5 feet above the road surface (estimated height for a driver s field of vision). From this point measure the distance to the object. All observations should be made in the direction of the traffic flow. For Inventory Sites having relatively long lengths, curves, and/or varying road slopes, collect a series of ASD beginning at the BMP and proceeding toward the EMP. Compare the ASD values collected and utilize the smallest recorded value as the ASD for the Inventory Site. This data will be recorded within the GHMS in Part B: Traffic Information. 30

37 c) Decision Site Distance (DSD) The Decision Site Distance (DSD) shall be determined by the latest version of the Geometric Design of Highways and Streets. The following table outlines the general DSD values for highways. TABLE Decision Sight Distance Design Speed DSD (ft)* (MPH) 25 > * Based upon the 2005 edition, Exhibit 3-3, Avoidance Maneuver C. Note: For Design Speeds less than 25 MPH use a DSD of 375 feet d) Percent Decision Site Distance (PDSD) After the DSD has been determined for the Inventory Site, calculate the percent decision site distance (PDSD). The following equation shall be utilized to calculate the PDSD: Eq. #1: PDSD = ASD / DSD * 100 If the calculated value is greater than 100 percent it is assumed that a driver will have sufficient time to stop prior to striking a rock within the roadway. The PDSD is an auto-calculated field within the GHMS in Part B: Traffic Information. Example presents the calculation of the PDSD. 31

38 Example : Percent Decision Site Distance Inventory Site with the following field data: MP 2.91 MP 3.26 Inventory Site Length = 1851 ft. Speed Limit = 55 mph DSD = 865 ft. ASD Readings = 850 ft., 865 ft., 799 ft., 860 ft., 579 ft. Site ASD = 579 ft. PDSD = ASD / DSD * 100 PDSD = (579 / 865) * 100 PDSD = 67% Slope Information The following are the field procedures for completion on the Rockfall Form in Section E: TIER 2 - SLOPE INFORMATION. For the respective locations within the GHMS, refer to the individual item. It should be noted that these data fields can be collected through either physical measurements utilizing a measuring wheel or tape, or through calculated methods. The following sections outline in detail procedures for the collection of the required data a) Slope Height All slope height measurements made for the Inventory Site shall be recorded as a vertical height recorded to the nearest foot. This data will be recorded within the GHMS in Part C: Slope Information, Geometric Information tab. Separate height measurements need to be recorded for the rock cut, any soil cut, and any backslope. Additionally, in extreme cases where large ranges of slope heights are present, especially along the Ohio River, the minimum and maximum ranges of the slope heights should be recorded within comments fields. Three methods of measurement can be performed to determine the slope height. The preferred method to determine the slope height is through the use of a rangefinder. Using the rangefinder, the total height can be calculated through trigonometric calculation based on the angle and distance from a fixed reference point. Automated profilers, such as laser face profilers, will internally calculate the distances and heights for the users. If heavy vegetation is present across the slope obscuring the slope geometry then this method may not be applicable. 32

39 An alternative to the profiler method is to calculate the slope height involving trigonometric calculations using field measurements collected with a pocket transit compass, clinometer, or transit, from the shoulder, median or roadway surface and measured distances. This method requires the collection of angles and and distances needed for the calculations outlined in Figure A minimum of three measurements should be collected of each angle and the average angle recorded to the nearest whole degree. If heavy vegetation is present across the slope obscuring the slope geometry, then this method should not be utilized. Another method is to perform physical measurement of the slope. For relatively short slope heights, a survey rod or measuring tape can be used for the height measurement. Generally, a survey rod can be used for a slope height less than 25 feet in height. If a measuring tape is utilized make sure that the tape is taunt and vertical, possibly utilizing a face-pole. Additionally, the slope height can be measured utilizing a hand or abney level and shooting spot heights up the slope. This method may be the most applicable for slopes that are heavily vegetated. Figure RELATIONSHIP BETWEEN SLOPE Total HEIGHT slope AND height= GEOMETRICAL (x) sin * sin PARAMETERS + HI sin (-) (adapted from Pierson et al., 1991) Total slope height HI EP x EP Eq. #2 Vertical Height x sin sin sin HI Height from Pavement Comments: HI =height of instrument (ft) x = distance between the two points used for measurement of angles (ft) and = angles measured from horizontal (degrees) EP = edge of pavement 33

40 EXAMPLE : Calculating the Slope Height Recorded Angle = 42º, 43.5º, 43.1º Avg. Angle = 42.9º Recorded Angle = 24.5º, 25º, 24.8º Avg. Angle = 24.8º X = 24 ft. HI = 5.3 ft Slope Height sin 42.9 sin (24) 5.3 sin Slope Height = 27 feet b) Slope Elevations All slope height measurements collected in Section a should be converted to slope elevations based upon a Section Base Elevation. This data will be recorded within the GHMS in Part C: Slope Information, Geometric Information tab. The Section Base Elevation is the approximated ground surface elevation at the edge of pavement where the height measurements were collected. The Section Base Elevation is estimated based on the change in ground surface height relative to the Inventory Site BMP Elevation collected as part of the BMP position. All elevations should be recorded to the nearest foot c) Slope Undercutting/Raveling For each Inventory Site, estimate the percentage of the slope experiencing undercutting and raveling. This data will be recorded within the GHMS in Part C: Slope Information, Slope Information tab. For sites where undercutting is occurring, any portion of the slope above the lowest location of undercutting should be considered as experiencing undercutting. Additionally, record the number of locations where undercutting is occurring for both the cut slope and natural backslope. Record the maximum, and average depth of undercutting being experienced in both the cut slope and the backslope. Raveling occurs when bedrock comprising the slope is completely broken either by natural jointing and weathering or due to blast damage generated during construction d) Slope Jointing Record the joint pattern(s) expressed within the Inventory Site relative to the orientation of the roadway. It is anticipated that generally this will only be accomplished for cut slopes. Natural slopes usually will not present sufficient 34

41 bedrock exposures, except where massive competent beds are present, to establish joint information. For sites where multiple joint patterns are expressed, record up to 3 principal or secondary joint sets. This data will be recorded within the GHMS in Part C: Geological Information, Joint Information tab e) Rockfall Source Information Determine source zone(s), or potential source zone(s), of rockfall debris along the rock slope. Typical source zones include, but not limited to: 1. more durable rock strata underlain by a less durable rock strata 2. intersection joint sets that are susceptible to freeze-thaw and ice wedging 3. weathered zones that are highly fractured 4. cut slope faces that have extensive blast damage from construction 5. any combinations of source zones 1 through 4 It should be noted that rockfall source zones can and are located in both the cut slope and or natural backslope of a slope. In some areas, the natural backslope will be a greater source of rockfall debris than the cut slope. Estimate the percentage of the slope that contains a rockfall source zone. The percentage of the slope is calculated by summing all the potential rockfall source zone heights located in the cut slope and the natural backslope and dividing by the total slope height (cut slope height added to the natural backslope height). Record the estimated potential rockfall that may occur from either the cut slope or the natural backslope. Estimate the maximum and average block size that may be produced as well as the anticipated volume which may be produced during a single rockfall event to a tenth cubic foot (0.1 ft 3 ). The block size can be determined by evaluating the discontinuities (joints, bedding, etc.) within the slope. Three components to the block size which need to be evaluated, with measurements recorded to the nearest tenth of a foot (0.1 ft), are; height (x), width (y), and thickness (z): Height (x): generally the distance from top of the rock strata to the bottom of the rock strata; or the persistence of the joint (total length that a joint is present within intact bedrock possibly crossing bedding surfaces) with the slope face Width (y): distance from one joint to another joint along the face Thickness (z): depth at which either the joints intersect or the thickness of the undercut or the distance to a joint set depth which runs parallel to the slope face 35

42 Figure demonstrates the dimensions of a block before and after falling. Estimate the anticipated total volume of debris that could be produced during a single rockfall event. At sites where thick competent beds are broken by regular repeating joint sets, as exhibited in the previous figure, the volume will be equal close to the maximum block size. However, in thin to thick bedded competent rock which is exhibiting raveling, the volume generated during a single event may be much greater than the maximum block size. When this is the case, debris volume can be estimated by evaluating the discontinuities (joints, bedding, etc.) within the slope and comparing them to how they are interlocked. Three components of the volume which need to be evaluated, with measurements recorded to the nearest tenth of a foot (0.1 ft), are; height (x), width (y), and thickness (z): Height (x): generally the distance along a persistent joint within the slope face which broken rock is located along which could dislodge during a rockfall event Width (y): lateral distance along the slope face along which uniformly broken rock is located Thickness (z): depth into the slope to which the persistent joint set which the height is being measured along Figure demonstrates the dimensions of a block with the potential of falling. 36

43 Figure a. Block Size Before Falling X = 7.2 ft Y = 14.6 ft Z = 4.9 ft Size: 7.2*4.9*14.6 = ft 3 X = 7.2 ft Y = 14.6 ft Z = 4.9 ft Size: 7.2*4.9*14.6 = ft 3 Figure b. Block Size After Falling Note: The block height is dictated by both the strata thickness and joint persistence which are the same dimensions. Figure BLOCK SIZE DETERMINATION 37

44 Figure ROCKFALL VOLUME DETERMINATION Comment: Green Outline represents the area of potential rockfall debris which could be generated during an event based on open jointing and raveling. The arrows indicate the dimensions. X = 15.3 ft Y = 13.5 ft Z = 3.8 ft Volume: 15.3*3.8*13.5 = 29.1 yd f) Hydrologic Conditions Evaluate the cut slope and the natural backslope for the presence of hydrologic conditions, both groundwater and surface water. The estimate of the hydrologic conditions should be based on the entire surface area of either the cut slope or the natural backslope. This data will be recorded within the GHMS in Part C: Hydrogeologic Information, Cut Slope Information, Natural Backslope Information, and Precipitation tabs. Groundwater can be either flowing (spring) or non-flow (seepage) that is discharging from the bedrock at the slope face, either the cut slope or natural backslope. Indicate if groundwater is present in the cut slope and/or the natural backslope. Record the percentage of the slope, cut slope and backslope respectively, to the nearest whole percentage. If the site inventory is conducted during winter months, the presence of groundwater may be masked due to ice buildup on the slope face from an isolated area of groundwater further up the slope. In this case, if the source of groundwater cannot be isolated, then the yes for groundwater needs to be recorded, but the slope will need to be re-evaluated after the ice has melted and the natural conditions can be sufficiently evaluated. 38

45 Additionally, record if surface water is present in the cut slope and/or the natural backslope. If erosion channels are present during dry seasons record yes for surface water. Record the percentage, to the nearest whole percent, of the cut slope and/or the natural backslope. Figure HYDROLOGIC CONDITIONS Comment: Note that heavy seepage appears to be originating at the cut slope/ natural backslope interface which is then creating an ice cover over the slope masking potential areas of additional seepage g) Corrective Actions Typical types of corrective actions for rock slopes include installation of concrete D-50 barrier, barrier fencing, construction of protective berm, construction of catchment area, scaling the slope, and re-grading the slope. The presence of guardrail along the road is not considered a type of corrective actions or method of catchment. Indicate if corrective actions were performed in the past. Define the type and location of the corrective actions. If known, record the date of the corrective actions, or NK if not known. If the slope was modified, record the percentage of the slope re-graded. If the catchment was modified, record the retention type, if applicable. This data will be recorded within the GHMS in Part C: Slope Information, Corrective Actions tab. The data is presented on the Rockfall Form in Section E: TIER 2 SLOPE INFORMATION. Figure presents typical types of catchment corrective actions found along Ohio roadways. 39

46 Figure TYPICAL TYPES OF CATCHMENT CORRECTIVE ACTIONS Type of Corrective Action Barrier Example Example Photograph Catchment Area: Sufficient area for adequate rockfall debris containment None Catchment Area Rockfall Debris Limited Catchment Area PCB: (Portable Concrete Barrier) D50 D32 40

47 Figure TYPICAL TYPES OF CATCHMENT CORRECTIVE ACTIONS (cont.) Limited Catchment Area CIP: (Cast in Place Concrete Barrier) Limited Catchment Area ODOT Rockfall Fence: Earthen Berm. 41

48 h) Catchment Catchment Area is defined for use in this Manual as: The area between the face of the rock slope and the edge of the travel lane capable of reducing the velocity of a rock particle traveling in a downslope trajectory from a source location along the rock slope. This definition differs from the design catchment area as a distinction is made between design and actual rockfall conditions. It should be noted that the area between the rock slope face and the roadway, which has a positive slope toward the roadway and/or is higher than the roadway, should not be considered catchment areas. If a stream is located between the slope and roadway, it can be counted as part of the catchment area. The catchment area shall be evaluated at its critical section. The critical section is the smallest ratio based upon the width of the catchment area versus the rock slope height, or largest volume that could be produced along the length of the Inventory Site. This data will be recorded within the GHMS in Part C: Slope Information, Catchment Area tab. The data is presented on the Rockfall Form in Section E: TIER 2 SLOPE INFORMATION aa) Catchment Area Shape The catchment area shape is based upon the simplified geometry of the catchment area. The catchment area shape should not be influenced based solely on the hydraulic control ditch, unless this ditch has sufficient size or geometry to act as a catchment area for rockfall debris. Basic catchment area shapes are flat, elliptical, circular, trapezoidal, or triangular. The standard Ritchie Ditch utilizes a trapezoidal catchment shape. The current FHWA/Oregon Catchment Ditch should be considered a triangular catchment area shape. When the majority of the catchment area is flatter than 8H:1V (7º from horizontal), the catchment area should be considered flat. Figure presents simplified schematics of catchment area shapes and example photos. 42

49 General Schematic Shape/ Abbrev. Picture Example Flat F Triangle V Trapezoidal T Elliptical E Circular C Figure Catchment Area Shapes 43

50 bb) Catchment Area Depth The catchment area depth is a physical measurement from the deepest point of the catchment area referenced to the road elevation. The ditch depth of the hydraulic control ditch (control of water runoff only) is not considered part of the catchment system unless the ditch is wide enough to act in the capacity of rockfall control. To collect the depth measurement, extend a plane from the road surface, such as a measuring tape or steel tape measure pulled taut, and determine the distance from the base of the catchment area to the extended plane using a folding scale or another tape measure. The depth should be an average of five recorded depths along the length of the ditch, unless the critical section is shallower than the remaining catchment area. The measurements shall be recorded to the nearest 0.1-foot. For catchment areas where a barrier wall or fence is located along the roadway shoulder, extend the plane from the top of the footing as the reference plane and add the height of the barrier to the depth. Figure shows a series of examples of the catchment area depth. Figure a. CATCHMENT AREA Road Elevation Catchment Width Catchment Ditch Depth Hydraulic Ditch Depth (NOT COUNTED since insufficient to retain rockfall debris) 44

51 Catchment Depth Catchment Width Catchment Width Catchment Depth Hydraulic Control Ditch (Not Counted) Figure b. Hydraulic Control Ditch NOT as Catchment Note: The flow line of the hydraulic control ditch should not be measured as catchment depth due to insufficient width for rockfall catchment. Figure c. Hydraulic Control Ditch as Catchment Note: This hydraulic control ditch can be measured as catchment depth due to sufficient width which will result in rockfall catchment cc) Catchment Area Width The catchment area width is a physical measurement from the edge of the travel lane to the face of the rock slope. The distance should be measured to the rock slope face, and not the outer edge of any talus buildup, since talus buildup can be removed as part of the ditch maintenance. To collect the width measurement, extend a plane from the road surface to the rock slope face, as outline in Section bb Catchment Area Depth. The measurement shall be recorded to the nearest 1-foot. For a catchment area with a uniform width across the slope, take an average of five measurements. If the catchment area has an area which is wider than the remaining catchment area, such as for a drainage basin, this area should be excluded from the measurements. However, if a section of the catchment area is narrower than the remaining catchment area this should be considered a critical section and the catchment width should be based on the average width of this section. Figure shows an example of the catchment area width dd) Foreslope Angle The foreslope angle is the angle measurement of the slope between the shoulder or edge of the travel lane and the bottom of the catchment area. This measurement shall be made from a horizontal plane extended from the road elevation and recorded to the nearest whole degree. If multiple angles are present within the foreslope then an average angle of the foreslope needs 45

52 to be recorded. A minimum of five measurements should be recorded across the length of the Inventory Site and averaged, excluding areas which have been drastically modified and are not representative of the catchment area. To collect the foreslope angle two options are available. The preferred method is by physical measurement by placing a two (2) or four (4) foot level along the foreslope and then record the angle measurement utilizing a clinometer. This method is not feasible at foreslopes where multiple angles are present. However, the angle can be estimated utilizing a pocket transit and visually estimating the average angle. An alternative method is by determining the angle trigonometrically by extending a plane from the road surface to the point of the catchment area depth (l) measurement and record the value to the nearest foot, and the catchment area depth (D) to the nearest foot. Use the following equation (equation #3) to determine the foreslope angle: l Eq. #3: tan A = D / l D A ee) Slope Face Angle The slope face angle is the angle of the rock slope face where the slope intersects the catchment area. This angle may not be the angle of the base of the ditch due to modification through past maintenance activities and should be reflective of the cut slope angle. The foreslope angle is the angle measurement of the slope between the shoulder or edge of the travel lane and the bottom of the catchment area. This measurement shall be made from a horizontal plane extended from the road elevation and recorded to the nearest whole degree. If multiple angles are present within the foreslope, an average angle of the foreslope needs to be recorded. To collect the angle measurement, two options are available. The preferred method is a physical measurement by placing a two (2) or four (4) foot level along the rock slope face and recording the angle utilizing a clinometer. This method is not feasible at foreslopes where large amount of talus 46

53 buildup is present. However, the angle can be estimated utilizing a pocket transit and visually estimating the average angle. An alternative method is by determining the angle trigonometrically by extending a plane along the same elevation as the road surface and measure the distance from the point of the catchment area depth to the rock slope face (f), record to the nearest foot, and utilize the catchment area depth (D), as determined in Section bb Catchment Area Depth, to the nearest foot. Use the following equation to determine the slope face angle: f Eq. #4: tan = D / f D This angle shall be recorded to the nearest whole degree less than 90º. l f f l A D D A Figure Catchment Area Configuration 47

54 ff) Remedial Effectiveness For areas were catchment areas are present or where past corrective measures have been implemented, estimate the effectiveness of the work expressed to the nearest 10 percent. The work effectiveness should be based on existing catchment geometry compared to the current guidelines outlined in Appendix B in addition to past history or evidence of rockfall debris relative to the slope and roadway. Inventory Sites where barrier corrective actions have been constructed does not mean that the effectiveness is 100 percent. Barrier effectiveness should be based on the barrier type relative to the debris type, size, volume, and ditch geometry between the barrier and the cut slope. For example a very large block size (>5 ft in diameter) will not be retained by a D36 or D50 cast in place wall if the catchment width is very narrow; or if the block is stopped by the wall the amount of debris as a result of the damage to the wall may pose a risk to the travelling public. Also, for Inventory Sites which may produce a large volume of debris with a narrow catchment area and a barrier along the shoulder, check the catchment capacity versus the potential rockfall volume. The catchment capacity is the calculated volume based on the barrier height and catchment width relative to the volume at the location where the high potential from which rockfall debris could be generated. If the debris volume calculation is greater than the catchment capacity, the remedial effectiveness should be less than 100 percent relative to the volume over the capacity i) Additional Information Record if mine openings are evident within the cut slope or the natural backslope as either yes or no. If yes, record within the comments section the number of openings, including condition of the opening(s) (sealed, open, collapsed, discharging drainage) and approximate location relative to the BMP. Also, note if acid mine drainage is present within the ditchline. Figure shows examples of mine openings within slopes. Record if any evidence of slope instability is noted in either the soil cut section or backslope as a yes or no under slope instability. If yes note the observations within the comments field and approximate location relative to the BMP. This data will be recorded within the GHMS in Part C: Slope Information, Corrective Actions tab. The data is presented on the Rockfall Form in Section E: TIER 2 SLOPE INFORMATION. 48

55 Abandoned mine opening not sealed but collapsed Abandoned mine opening Entrance sealed with bricks Mine subsidence within a cut slope Acid mine drainage within ditch Figure EXAMPLE OF MINE OPENINGS 206 TIER 3 & TIER 4 SITE DATA COLLECTION Upon completion of the Tier 2 Data Collection any site which scored as a Tier 3 or Tier 4 site should have the final data sets completed. There is no difference in data collection between a Tier 3 and Tier 4 site. However, if a Tier 4 site is identified, OGE and the respective DGE or designated District Rockfall Inventory Coordinator needs to be notified within 24 hours so that appropriate actions can be taken. Generally, the best way to complete the data collection is through direct measurements from the slope face by performing horizontal and vertical line survey(s). If the entire slope is not obtainable from the road surface, the slope face shall be inspected, evaluated and sampled by either climbing the face or repelling from the top Slope Geological Conditions The following information needs to be complied in Section F: Tier 3 & Tier 4 - Slope Geological Conditions. As previously noted, the slope information should be recorded relative from the ditch to the crest of the cut. 49

56 Number of Cut Slope Benches Record the number of benches located on the cut slope by physically counting the number of benches from the base of the slope to the top of the slope. This data will be recorded within the GHMS in Part C: Slope Information, Slope Information tab Number of Cut Slope Angles Record the number of slope angles located on the cut slope by physically counting the number of significantly different slope angles from the base of the slope to the top of the slope. The differentiation of slope angles should be relative to gross changes in the slope angles since cut slope angles can have variations across the length of a cut due to construction techniques, minor physical property changes within a rock strata, and differences on weathering over time. Typically, during a cut slope design and construction, slope angles will change dramatically (i.e. 0.25:1 increment or greater). Minor incremental changes in the slope angles are typically not discernable by the naked eye and should be considered one slope angle. This data will be recorded within the GHMS in Part C: Slope Information, Slope Information tab Cut Slope Angles Collect the cut slope angle(s) along the cut slope face by recording the slope angle from a horizontal plane using either a pocket transit, structural compass, or clinometer. To record the slope angle use a non-ferric (aluminum or plastic) clipboard or a 2- to 4-foot level placed against the cut slope face to estimate the slope angle. If blast holes (half casts) are still evident within the cut slope face record the slope angle along the central axis of the blast hole. An alternative method is to visually line up the slope angle with the edge of a pocket transit, structural compass, or clinometer and then determine the angle using the clinometers needle. Figure presents diagrams on how to determine these angles. Collect a minimum of three readings per slope angle and use the average value rounded to a whole degree. This data will be recorded within the GHMS in Part C: Geological Information, Slope Information tab. 50

57 Use of a pocket transit or structural compass for direct measurement for the slope surface. (From Brunton GeoTransit Operators Manual, 2001) Use of a pocket transit or structural compass for a visual measurement of the slope angle. (From Brunton GeoTransit Operators Manual, 2001) Figure SLOPE ANGLE DETERMINATION For slopes were talus buildup is present at the base of the slope angle, take either direct measurement from the slope above the talus, or estimate through sighting assuming the talus material is not present. Figures and show the collection of a slope angle utilizing a pocket transit for both a slope face and along a blast hole, respectively. Figure Recording slope angle along a blast hole using a pocket transit 51

58 Figure Recording slope angle using a pocket transit and non-ferric clipboard Average Cut Slope Angle After all the slope angles have been recorded, the average slope angle shall be calculated for the cut slope. The average slope angle shall be a weighted average of all the cut slope angles recorded to the nearest whole degree. Table provides typical design cut slope angles. Figure and associated example outlines the calculation of the weighted average of the slope angle. TABLE TYPICAL SLOPE ANGLES FOR ROCK CUTS Slope Angle Cut Slope Ratio 76º 0.25H:1.0V 63º 0.50H:1.0V 53º 0.75H:1.0V 45º 1.0H:1.0V 34º 1.5H:1.0V 26º 2.0H:1.0V 22º 2.5H:1.0V 18º 3.0H:1.0V 52

59 Figure AVERAGE SLOPE CALCULATION Weighted Heights A1 Height = 20 /75 = 0.27 A2 Height = 15 /75 = 0.20 A3 Height = 10 /75 = 0.13 A4 Height = 30 /75 = 0.40 Slope Angles Angle A1 = 45º Angle A2 = 63º Angle A3 = 26º Angle A4 = 76º Bench Width B1 = 10 ft. Catchment Area Roadway 45º 63º A1 B1 A4 76º 26º A3 A2 15 ft 20 ft 30 ft 10 ft 75 ft Eq. 5 Avg. Slope Angle = (A n* H n) Avg. Slope Angle = {(0.27*45º) + (0.20*63º) + (0.13*26º) + (0.40*76º)} = 58.5º or 59º EXAMPLE : Weighted average calculation for multi-angled cut slopes Cut Slope Angles Elevations Record the elevation(s) at which the cut slope angle changes using a measuring tape, survey rod, hand level, abney level, or methods outlined in Section a Slope Height. Record the elevation to the nearest foot. This data will be recorded within the GHMS in Part C: Geological, Single-angle tab Bench Elevations Record the height (elevation) at which the benches are located along the cut slope using a measuring tape, survey rod, hand level, abney level, or methods outlined in Section a Slope Height. Record the elevation to the nearest foot. If the bench is not a true horizontal bench, but a sloping bench (such as a stratigraphic bench), record the percent (%) slope for the bench. This data will be recorded within the GHMS in Part C: Geological tab. 53

60 Bench Width The bench width measurement is a physical measurement made with either a measuring tape or distance wheel. If talus material covers part, or all, of the bench, use an estimated width for the original bench width. Record this width to the nearest foot. This data will be recorded within the GHMS in Part C: Geological, Bedding information tab. EXAMPLE : Calculation of Bench width and Elevation (From Figure ) Road Elevation (Section Base Elev.) = 879 Ft Bench B1 Height (Elevation) = 35 Ft (914 Ft) Bench B1 Width (Ft) = 10 Ft Competent Bedding Record the number of competent beds present within the cut slope including the bed lithology, bedding, bedding JRC (see Appendix F for listing), and aggregate thickness of all competent beds. Record this measurement to the nearest foot. This data will be recorded within the GHMS in Part C: Geological Information, Bedding Information tab Incompetent Bedding Record the number of incompetent beds present within the cut slope including the bed lithology, bedding, bedding JRC (see Appendix F for listing), and aggregate thickness of all incompetent beds. Record this measurement to the nearest foot. This data will be recorded within the GHMS in Part C: Geological Information, Bedding Information tab Undercutting Information Record the number of competent beds that have undercutting within the cut slope including the maximum and average depth of undercutting and average thickness of undercutting. Additionally, note any undercutting that may be occurring within the natural backslope including maximum and average depth of undercutting and thickness of undercutting. Record the measurements to the nearest tenth foot over an average of five measurements. This data will be recorded within the GHMS in Part C: Geological Information, Bedding Information tab. 54

61 7: Clayey shale, thin bedded with partial vegetation 15ft 6: Shale, thin bedded 31ft 5: Siltstone, thick bedded 4: Coal/Carbonaceous 3: Siltstone, thick bedded 3ft 4ft 10ft 2ft 80 ft. 2: Claystone, thick bedded 15ft 1: Talus Block from Face Undercutting of incompetent bed beneath competent siltstone bed Figure EXAMPLE OF CUT SLOPE DESCRIPTION EXAMPLE : Slope Geological and Natural Conditions (from Figure ) Comments: In this example the coal/carbonaceous shale layer (4) and the claystone layer (2) would be considered incompetent beds due to the overlying more durable siltstone layers (3 & 5). The shale (6) located above the siltstone (5), toward the top of the cut slope, would be considered a durable layer since the overlying clayey shale (7) is not a more resistant layer. Basal Talus Accumulation: 15 ft Number of Competent Bed(s): 4 Aggregate Thickness of Competent Bed(s): 51 ft Competent Bedding: thin to thick Number of Incompetent Bed(s): 2 Aggregate Thickness of Incompetent Bed(s): 14 ft Incompetent Bedding: thin to thick Number of Competent Bed(s) with Undercutting: 2 Maximum Undercut Thickness: 3.5 ft Average Undercut: 2.0 ft Average Depth of Undercut: 4.0 ft Ratio: Number of Competent to Incompetent Beds: 2.0 Ratio: Aggregate Thickness of Competent to Incompetent Beds: 3.6 (Note that the Ratios will be an auto-calculated field within the database) 55

62 Joint Information Record the information concerning the jointing of the cut slope face. Natural backslopes may present adequate bedrock exposures within massive, competent bedrock types in which joint information may be determined. Indicate the type of joint(s) present within the slopes as either Orthogonal Joints (ORTH) or Valley Stress Relief Joints (VSRJ) and the number of joint sets. Appendix F outlines the general difference between these two types of joints. Record the orientation of the joint set(s) utilizing a Brunton or lensatic compass, recorded to a whole degree. Measure and record the average width of each joint and the spacing between the joints within a joint set(s) for each of the competent and incompetent beds using either a tape measure, folding scale, or a distance wheel. These measurements should be recorded to the nearest tenth foot. Visually estimate the average percentage of the joints within each joint set(s) that contains infilling for each of the competent and incompetent beds. Record the estimate as a whole percent. Additionally, note the type of infilling present within the joint set (examples clay, iron precipitation, mineralization, etc.). This data will be recorded within the GHMS in Part C: Geological Information, Joint Information tab. Figures and present examples of joints and joint infilling for strata within a cut slope. EXAMPLE : Collection of Joint Information Joint Orientation: ORTH / VSRJ Orientation of Joint Set(s) = 182º; 175º Avg Spacing of Joint (competent) = 15 ft. Joint Width (competent) = 0.7 ft. % of infilling of Joint = 55 % Type of Infilling = Clay Avg Spacing of Joint (incompetent) = 15 ft. Joint Width (incompetent) = 0.5 ft. % of infilling of Joint = 100 % Type of Infilling = Clay 56

63 Joint Spacing Figure ORTHOGONAL JOINT SET/SPACING No Clay Infilling Joint Width 50% Clay Infilling 100% Clay Infilling Joint Width Figure JOINT INFILLING 57

64 Potential Rockfall Estimation Estimate the anticipated shape of the blocks that may occur during a rockfall event relative to the shapes modeled with the Colorado Rockfall Simulation Program (CRSP). Three basic shapes utilized by CRSP are: Spherical: a rock with uniform size and shape in all dimensions Cylindrical: a rock that has one axis longer (length) than the other two axes which are roughly equal in size Discoidal: a rock that has a uniform diameter and length, but the thickness is significantly less than the length or diameter (slab or flagstone) A slab type rock typically seen within the interbedded strata typically found within Ohio would fall into the discoidal category. All the parameters should be recorded to the nearest 0.5-foot. Table outlines each of the parameters required for each particle shape. Figure shows examples of each: TABLE : ROCKFALL PARAMETERS Shape Diameter Length Thickness Spherical Cylindrical Discoidal : Indicates the parameter measurement required for rock shape. Figure EXAMPLE ROCKFALL SHAPES Spherical Cylindrical Discoidal 58

65 Estimate the maximum extent that a single rockfall event will impact the roadway. Record the estimated limits of impact as a linear distance relative to the roadway, both parallel and perpendicular to the slope. The impact length should be measured as a lateral distance parallel to the slope from which debris may be produced. The length may be greater than the estimated width (y) estimated for Section e) Rockfall Source Information. The impact width should be estimated as the lateral distance parallel from the base of the cut slope face to which the rockfall debris will extend. These estimates should be recorded to the nearest foot. This data will be recorded within the GHMS in Part C: Geological Information, Additional Information tab Talus Accumulation For estimation of the talus accumulation, both basal and along benches, look at the location where the maximum accumulation is present and evaluate this location as a worst case situation. Evaluate the worst case location as a section to determine the percentage of talus build up relative to the catchment or bench width. Record this value to the nearest whole percentage. Figure illustrates the calculation of the talus buildup along a bench. Each bench should be calculated separately with a percentage value recorded for each bench location. This data will be recorded within the GHMS in Part C: Geological Information, Bedding Information tab. 59

66 25% 50% 75% 100% Talus Accumulation Along Bench Width 0 2.5ft 5.0ft 7.5ft 10.0ft Bench Width = 10 ft. Figure ESTIMATING TALUS ACCUMULATION ON A BENCH Vegetation Estimate the percentage of both the cut slope and natural backslope that contains vegetation based on aerial extent of the slope. Record the estimate to a whole percent. Additionally, within the comments section, record the type and size of the vegetation. Typical category types () and sizes ( ) are: Grasses Shrubs/scrub Trees > 12 This data will be recorded within the GHMS in Part A: General Information Additional Information Upon completion of the Tier 3 and Tier 4 Slope Geological Conditions, record within the comments section if any anomalies are noted within the slopes (e.g. faults, coal riders, etc.). This data will be recorded within the GHMS in Part C: Geological Information, Additional Information tab. 60

67 206.2 Slope Hydrological Conditions The following are the procedures for completion of the GHMS Part C: Hydrogeological Information which is also found in the Rockfall Form in Section G: TIER 3 & TIER 4 FIELD SLOPE HYDROLOGICAL CONDITIONS. This basic information pertains to the groundwater and surface water conditions of the cut slope and/or natural backslope within an Inventory Site. This data is collected through visual evaluation and by performing physical measurements of the slope. Evaluate the cut slope and the natural backslope for the presence of groundwater. Groundwater can be noted as either flowing (spring) or non-flowing (seepage) that is discharging from the bedrock or soil cover along the slope face. Record if groundwater is present in the cut slope and/or the natural backslope. Hydrological conditions should be noted on the site plan and details, including the location based on the discharge point(s). All measurements should be noted from the BMP location. Distances should be determined based along the edge of pavement until perpendicular to the referenced location. Elevations should be determined as outlined in Section a Slope Height and Section b Slope Elevation. The following types of hydrological conditions should be noted: Spring: An isolated point within the slope where groundwater is discharging Spring Line: A series of springs which are located along the same elevation Seep: An isolated point of moisture within the slope which is not comprised of flowing groundwater Seep Line: A series of seeps which are located along the same elevation Seep Zone: An area within the slope where seepage is noted from multiple sources in close proximity to each other at varying elevations Surface Flow: An erosional channel developed form the channelization of surface water runoff Additional measurements are required for spring and seep lines and seep zones. For spring or seep lines, the length that the line extends along the slope face needs to be recorded. For seep zones, the distance from the BMP should be referenced to the first noted edge of the zone with the length being referenced to the furthest edge of the zone. The elevation of a seep zone will be referenced to the base of the seep zone. The hydrologic conditions for the Inventory Site should be recorded across the Inventory Site beginning at the BMP at the base of the slope proceeding upslope then across the site to the EMP. All springs and seepage should be assigned a site specific ID referencing and numerically numbered in the order that they are encountered with a prefix designation outlined in Table

68 TABLE 200-6: HYDROLOGICAL PREFIXES Hydrogeological Condition Spring(s) Spring Lines(s) Seep(s) Seep Line(s) Seep Zones(s) Surface Flow Abbreviation The following examples demonstrate the general outline of how to reference the site hydrological conditions. SP SL SE SH SZ SF 62

69 Figure HYDROLOGIC CONDITIONS WINTER CONDITIONS Surface Flow Elev. Ft Spring Line BMP GPS Obtained Elev. 960 Example : Hydrologic Conditions of Cut Slope and Natural Backslope Comments: Note that water is present at overburden and rock interface. However, due to the cold conditions at the time of the site inventory the groundwater has resulted in ice formation along the entire slope face. Thus reducing the potential for observations and identification of possible additional hydrologic conditions within the lower slope. Surface flows are evident within the picture where the ice buildup along the face is greatly reduced or voided, and deep erosional rills are present in the soils natural backslope. These locations should be noted as Surface Flows within the natural backslope since this is where they originate as evidence of the rills. Cut Slope Info: Site ID# Dist. From BMP (ft) Length (ft) Elevation (ft) Flow Rate (gpm) SL <1.0 gpm Pictures taken at all locations: Y / N Backslope Info: Site ID# Dist. From BMP (ft) Length (ft) Elevation (ft) Flow Rate (gpm) SF1 350 NA 1085 NA SF2 380 NA 1085 NA SF3 460 NA 1085 NA Pictures taken at all locations: Y / N 63

70 Figure HYDROLOGIC CONDITIONS SPRING CONDITIONS Seepage Zone Seeps Saturated Surface from Seepage Seepage Line Saturated Surface from Seepage 746 (BMP Elev.) Left Side of Picture Example : Hydrologic Conditions of Cut Slope and Natural Backslope Comments: Note that seepage is prevalent throughout the slope. Dashed red line indicates the cut slope/backslope interface. Areas of seepage have saturated the slope, but are not part of the seep itself. Cut Slope Info: Site ID# Dist. From BMP (ft) Length (ft) Elevation (ft) Flow Rate (gpm) SZ < 1.0 SH < 1.0 SE1 115 NA 786 < 1.0 SE3 148 NA 765 < 1.0 Comments: Backslope Info: SZ1 is located just below natural backslope interface; SH1 is located along a bedding plane. Pictures taken at all locations: Y / N Site ID# Dist. From BMP (ft) Length (ft) Elevation (ft) Flow Rate (gpm) SE2 123 NA 771 < 1.0 Comments: SE2 is located just above the cut slope/backslope interface. Pictures taken at all locations: Y / N 64

71 206.3 Tier 3 & Tier 4 Testing Data The following are the procedures for completion of the GHMS Part C: Rock Sampling Information which is also found in the Rockfall Form in Section H: TIER 3 & TIER 4 TESTING DATA. Section H records the information concerning sample collection for Tier 3 and Tier 4 site. Slake Durability Index testing (SDI) will be performed on selected representative samples collected from the slope of the rockfall sites rated as either Tier 3 or Tier 4 from the Preliminary Slope Rating. For large sites that have many different rock strata, collect a maximum of six samples for SDI testing. If more than six incompetent beds are present within an Inventory Site, collect samples from the six deepest, or worst, locations across the site. Collect bag samples of fresh rock material from each incompetent bed located within the slope. Coal, limestone and moderately hard sandstone strata should not be sampled for testing. The weathered rock surface should be removed from the slope face using a shovel, geologic hammer, mattock, and/or chisel until fresh competent bedrock has been exposed. Once the fresh rock face has been exposed, collect a sample of the fresh rock material and place it into a collection bag(s) or container for preservation. The material should be collected in such a manner and placed in a container that moisture loss and breakage of the sample will be minimal during transport and storage prior to testing. During transport and storage the sample should not be allowed to freeze. Refer to ASTM D 4644 for the type and amount of sample specimen required to perform the test. On the plan view, record the approximate locations where the samples were collected. Record the sample location by referencing the location as a distance from the BMP to the nearest foot and elevation relative to the BMP to the nearest foot. Record the sample data on the sample container, or on a sample tag affixed to the container, and on a completed chain of custody form, include the following information: Site Location as County-Route-Section ODOT District Travel Direction (Cardinal or Non-Cardinal) Distance from BMP Right or Left Offset Sample ID# Height relative to BMP Number of containers collected per sample Date sample collected Person collecting the sample The bag samples should be delivered to the respective testing laboratory within a week of the sample collection. 65

72 Upon completion of the testing data, record the sample test results in Section H: TIER 3 & TIER 4 TESTING DATA. For sites where multiple samples have been collected, record the number of SDI tests performed with the high and low test results with an average test results. Example : Slake Durability Index Test Sample Collection Removal of weathered bedrock for SDI sample collection SDI Sample collected (including field identification) SDI Sample (prior to testing) SDI Sample (post testing) 66

73 206.4 Tier 3 & Tier 4 Office Data Tier 3 and Tier 4 sites, as determined from the Preliminary Rating, will require additional traffic information not outlined in Section Geometrics and Traffic. This data includes: Average Road Slope Detour Distance Detour Time Auto Detour Time - Truck The detour information will not have been obtained during the interviewing process outline in Section ODOT Interview(s). The District Transportation Manager will need to be contacted to obtain this information. ODOT has set guidelines for how a roadway will be detoured based upon the road type and location. The District Transportation Manager will have to determine this information for each Tier 3 and Tier 4 site. This data will be presented in GHMS Part B: Traffic Information and in the Rockfall Form in Section I: TIER 3 & TIER 4 OFFICE DATA. Also, the precipitation history should be recorded for the site. The 1-day, 3-day, and 15-day precipitation history from the date of field data collection should be reviewed and recorded. If more than one day was spent working on the field data collection for the Inventory Site, the precipitation history should be referenced to the actual day that site hydrogeology data was recorded. This information can be obtained commercially from NOAA, or a request can be made to the Ohio Department of Natural Resources, Division of Water. Web links for sites to obtain the precipitation histories are available in Appendix B. This data will be presented in GHMS Part C: Hydrogeological Information, Precipitation tab and in the Rockfall Form in Section I: TIER 3 & TIER 4 OFFICE DATA. 207 DATA COLLECTION ACKNOWLEDGEMENT Upon completion of the field data collection, the Field Team should sign and date the form to acknowledge that the all the information collected and presented is accurate to the best of their knowledge. This signature can be either hand written or an electronic stamp and is located in Section K: DATA COLLECTION ACKNOWLEDGMENT. 67

74 300 Risk Scoring for Inventory Sites 301 Rockfall Inventory Site Risk Scoring After completion of the field data collection, Inventory Sites which are Tier 2, Tier 3, or Tier 4 risk sites will need an associated Inventory Site Risk Score (Risk Score) developed. The Risk Score is calculated based on ten (10) factors which are: 1. Differential Weathering 2. Discontinuity Role 3. Block Size/Volume of Rockfall per Event 4. Hydrologic Conditions (seeps and springs) 5. Rock Slope Height 6. Catchment/Containment 7. Exposure Risk 8. PDSD 9. Rockfall History 10. Accident History Each factor will develop a raw value score based on the recorded field data. Each evaluation parameter has a specific equation in which the site specific raw value (RV) is a field input. A weighting factor is applied to each evaluation parameter to provide an evaluation parameter score. The evaluation parameters values are summed to calculate the Inventory Site Risk Score The following sections outline the scoring for each factor. 302 Differential Weathering The differential weathering factor is a multi-variable factor based upon the Tier scoring. For Tier 2 sites the score will be based upon the recorded maximum visible undercut recorded within the cut section. This information is recorded in the Geological Hazard Management System (GHMS), Part C Geology: Additional Information Tab. The following scoring matrix should be utilized based on the depth of the undercut (RV): 5.6*(RV³) *(RV²) *RV For Tier 3 and Tier 4 sites, where slake durability (SDI) samples were collected and tested, the score will be based on the highest value between the SDI and undercut scores. The testing information is recorded in the GHMS, Part C Geology: Additional Information Tab. The following scoring matrix should be utilized based on the test results of the second cycle slake durability index (RV): *(RV³) *(RV²) *RV A minimum of 0 points and a maximum of 81 points need to be assigned for this section. 68

75 303 Discontinuity Role The Discontinuity Role factor is a multi-variable factor based upon the major type of discontinuity producing the rockfall debris. Typically, one of two types of discontinuity will be predominately controlling factor in production of rockfall debris. These are jointing or raveling. Cut slopes can exhibit either one or both of these properties. The slope should be evaluated for both types of discontinuities and scores based on the worst case of the two. The following is a brief discussion of how to score each type. Intersecting joint sets can produce blocks that can dislodge resulting in a potential hazard to the roadway. However, if the joint sets do not intersect, then the resulting discontinuity may not result in potential hazard to the traveling public. The scoring is based upon how continuous the joint set(s) are and the orientation of the joint set(s) relative to the roadway. This information is found in the GHMS in Part C: Geological Information, Joint Information tab. The following scores are assigned based on how continuous and the orientation of the joint(s): Discontinuous joints with favorable orientation = 3 points Discontinuous joints with random orientation = 9 points Discontinuous joints with adverse orientation = 27 points Continuous joints with adverse orientation = 81 points For slopes where the raveling is the predominate feature producing the rockfall debris, the score will be based on the percentage of the slope which is exhibiting the raveling (RV). The following scoring matrix should be utilized based on the depth of the undercut: 0.028*(RV³) *(RV²) *RV A minimum of 3 points and a maximum of 81 point need to be assigned for this section. 304 Block Size/Volume of Rockfall Per Event This factor is based on the size and amount of debris which could be a potential hazard to the traveling public. These variables are typically directly proportional to the type of joint sets and raveling that the slope is experiencing. Typically, either large blocks produced by the joint sets or small blocks produced by raveling is the predominate mechanism of debris generation. Both should be evaluated and scores based on the worst case of the two. The following is a brief discussion of how to score each type. The first variable to look at is the maximum dimension of the anticipated or recorded block size that could be produced for the slope. This information is recorded in the GHMS, Part C Geology: Additional Information tab. The following scoring matrix should be utilized based on the block size: 28*(RV³) - 136*(RV²) + 219*RV

76 The second variable to look at is the total volume of debris that could be produced for the slope during a rockfall event. This information is recorded in the GHMS, Part C Geology: Additional Information Tab. The following scoring matrix should be utilized based on the block size: 1.037*(RV³) *(RV²) + 73*RV A minimum of 0 points and a maximum of 81 point need to be assigned for this section. 305 Hydrologic Conditions (seeps and springs) The Hydrologic Condition factor is based on the percentage of the slope which has hydrologic conditions within the slope. This information can be found within the GHMS in Part C: Hydrogeologic Information, Cut Slope Information, Natural Backslope Information, and Precipitation tabs. The following scoring matrix should be utilized based on the percentage of the slope with hydrological conditions: *(RV³) *(RV²) *RV A minimum of 3 points and a maximum of 81 point need to be assigned for this section. 306 Rock Slope Height The fifth factor to consider in the Risk Scoring is the rock slope height from which potential rockfall debris could be generated. For Inventory Sites where the source zone is solely within the cut slope, the Rock Slope Height will be the Rock Cut Height. If the Inventory Site has a source zone located within the natural backslope, then the Rock Slope Height will be recorded as the Backslope Height. This information can be found within the GHMS in Part C: Slope Information, Geometric Information tab. The following scoring matrix should be utilized based on the rock slope height: *(RV³) *(RV²) *RV A minimum of 0 points and a maximum of 81 point need to be assigned for this section. 307 Catchment/Containment The Catchment/Containment factor is a multi-variable factor based upon existing catchment area and any past remedial activities. For sites where a retention (containment) system is in place (e.g. D50 wall, rock fence), the system is evaluated on whether the system is functional or not. For sites which do not have a containment system the site is evaluated based on the catchment area effectiveness. A reminder, just because a wall is in place does not necessarily mean that the wall will be effective for either very large block sizes or large debris volumes with small catchment storage capacity. This should be reflected in the estimated remedial work effectiveness. This data will be recorded within the GHMS in Part C: Slope Information, Corrective Actions tab. The following scores are assigned based whether there is a functional retention (containment) system in place: 70

77 Yes = 9 points No = 81 points Even though there is a functional barrier the site scores 9 points because there has been a problem in the past which has warranted the installation of the barrier. Additionally, if the barrier is subjected to repeated impacts the barrier may eventually fail, which is why a score of 3 is not assigned for functional barriers. For Inventory Sites which do not have a means of containment, all the debris control is handled based on catchment width and geometry. The effectiveness of the catchment area should be evaluated based on Appendix B. This data will be recorded within the GHMS in Part C: Slope Information, Catchment Area tab. The following scoring matrix should be utilized based on the catchment area effectiveness: *(RV³) *(RV²) *RV A minimum of 0 points and a maximum of 81 point need to be assigned for this section. 308 Exposure Risk This factor is based on the exposure risk that the Inventory Site as expressed to the travelling public. Exposure Risk can be calculated as following: Eq. #6: Exposure Risk ( ADT * SiteLength ) / 24 *100 SpeedLimit Note: The site length should be reported in miles ADT and speed limit values can be obtained from the GHMS in Part B: Traffic Information. The site length is recorded in Part A: Site Location of the GHMS. The following scoring matrix should be utilized to calculate the risk score for the exposure risk of the inventory site: *(RV³) *(RV²) *RV A minimum of 0 points and a maximum of 81 point need to be assigned for this section. 309 Percent Decision Sight Distance (PDSD) This Risk Scoring factor is based on the percentage decision sight distance. This is relative to the ability of a driver to react to an obstacle, such as rockfall debris, within the roadway. Percent Decision Sight Distance can be calculated as following: Eq. #1: PDSD = ASD / DSD 71

78 This data will be recorded within the GHMS in Part B: Traffic Information. The following scoring matrix should be utilized based on the Percent Decision Sight Distance: *(RV³) *(RV²) *RV A minimum of 0 points and a maximum of 81 point need to be assigned for this section. 310 Rockfall History The Rockfall History factor is based on the Inventory Site s rockfall maintenance records. These records are obtained from the applicable County Garage, County or Transportation Manager, or District Geotechnical Engineer. Rating scores are assigned as follows: Less than Annual Maintenance = 3 points Annual Maintenance = 9 points Semi Annual Maintenance = 27 points Constant Maintenance = 81 points Table presents the Rockfall History section of the worksheet. Evaluation Parameter Rockfall History Score Table Rockfall History Rating Scores for each Evaluation Parameter < Annual Maintenance Annual Maintenance Semi Annual Maintenance Constant 311 Accident History The final factor is the Accident History of the Inventory Site relative to past rockfall events. Accidents which did not involve debris generated from a rockfall event should not be considered. This factor is based on the County maintenance records and Department of Public Safety records with scores assigned based as follows: No Accidents = 3 points Minor Property Damage = 9 points Major Property Damage = 27 points Death = 81 points 72

79 Table presents the Accident History section of the worksheet. Evaluation Parameter Rockfall History Score Table Accident History Rating Scores for each Evaluation Parameter No Accident Minor Property Damage Major Property Damage Death 73

80 400 Inspection Frequency Each Inventory Site will require periodic re-inspection to determine if the site s risk is remaining relatively stable, or progressing as an increased risk relative to the public safety. The frequency of re-inspection will be based on the Preliminary Rating of the previous inspection as presented in Table Table Re-Inspection Frequency Rating Frequency Non-rated (Tier 1) 10 Years Moderate Risk (Tier 2) 5 Years High Risk (Tier 3) 3 Years Very High Risk (Tier 4) Annually Re-inspection will be required outside of the prescribed inspection table if one of the following events occur: 1. If rockfall debris fragment(s) greater than 6 inches in any dimension occupies the shoulder, travel lane(s) or median: The District Geotechnical Engineer (DGE) and the Office of Geotechnical Engineering (OGE) shall be notified within one week and the site shall be re-evaluated within one month of the event. 2. If rockfall debris greater than one cubic foot in total volume, occupies the shoulder, travel lane(s) or median: The District Geotechnical Engineer (DGE) and the Office of Geotechnical Engineering (OGE) shall be notified within one week and the site shall be re-evaluated within one month of the event. 3. A single rockfall event which produces debris volumes which occupies more than 70 percent of the estimated storage capacity over a length of 20 feet for the catchment area: The site should be re-inspected within three months of the event. 4. Remedial activities to the slope, partial or full, are performed on a site to reduce the overall relative risk: The site should be re-inspected within one year upon completion of construction activities. 74

81 APPENDIX A Glossary of Terms

82 APPENDIX A GLOSSARY OF TERMS Rock Type Terms: The following are descriptions of the basic rock types found within Ohio rock slopes. This listing is not intended to be an all inclusive exhausting listing. The following listing is presented in alphabetical order. Breccia: A coarse-grained sedimentary rock comprised of >25% subangular to angular coarse-grained sand, gravel and/or cobbles. These grains are supported by a matrix of finer sands, silt and/or clay and cemented by calcite, hematite, silica or hardened clay. Color depends on the matrix and cementing agent with typical colors of white, gray, yellow, orange, brown, and red common. CHERT: A hard dense microcrystalline or crptocrystalline sedimentary rock consisting of quartz crystals and may contain amorphous silica. Chert may be a variety of colors, but commonly range from brown to black. When broken it produces conchoidal fractures. These fractures are smooth with sharp edges. Chert forms as nodular or concretionary segregations or nodules or as layered deposits in limestone and dolomite. CLAYSTONE: A fine-grained detrital rock formed from particles finer than silt. Claystone is comprised of indurated clay having the texture and composition of shale, but lacking the laminations and fissility of a shale. Claystone may range in color from red, gray, olive, or brown, and slickensides are common. COAL: A combustible rock containing >50%, by weight, and >70%, by volume, of carbonaceous material; formed from the compaction and induration of plant remains. Colors of coals range from brown to black. Generally light weight with a shiny appearance on fresh surfaces. CONGLOMERATE: A coarse-grained sedimentary rock comprised of >25% rounded to subrounded coarsegrained sand, gravel, cobbles, and/or boulders. These grains are supported by a matrix of finer sands, silt and/or clay and cemented by calcite, hematite, silica or hardened clay. Color depends on the matrix and cementing agent with typical colors of white, gray, yellow, orange, brown, and red common. DOLOMITE: A sedimentary rock of which >50% consists of the mineral dolomite (calcium magnesium carbonate CaMg(CO 3 ) 2 ) and less than 10% is comprised of the mineral calcite. Commonly interbedded with limestone, and the magnesium can be replaced with ferrous iron. Dolomite is typically white to light colored and will be slow to react with cold dilute hydrochloric acid (HCl). Generally, for dolomite to react with HCl either a fresh or powdered surface is required. FIRECLAY: See Underclay for description. LIMESTONE: A sedimentary rock consisting of the mineral calcite (calcium carbonate CaCO 3 ). Very fine grains may not be visible to the naked eye. Impurities may included chert, clay and minor mineral crystals. May be crystalline (hard, pure, medium to coarse texture) and/or fossiliferous (remains of organisms). Limestone is typically white to dark gray in color and reacts vigorously with dilute HCl. SANDSTONE: Clastic sedimentary rock comprised of grains of angular or rounded sand in a matrix of silt and/or clay cemented together by silica, iron oxides, or calcium carbonate. Color depends on the cementing agent with white, gray, yellow, orange, brown, and red colors common. SHALE: Fine-grained detrital sedimentary rock formed be the compaction of clay, silt or mud. Shale is well indurated and has a laminated structure, which gives it fissility along which the rock splits readily. The predominate particle size is <0.002 mm (colloidal) and commonly interbedded with sandstone. Shale can be calcareous (contains calcite), carbonaceous (contains organic materials), and/or fossiliferous (contains remains of organisms). Carbonaceous shale often grades into coal. Typical colors may be red, brown, black, green or gray.

83 SILTSTONE: Fine-grained detrital sedimentary rock formed from particles finer than sand, but coarser than clay. Siltstone is comprised of indurated silt and have the texture and composition of shale, but lacking the lamination or fissility. Gray, olive, or brown are typical colors of siltstone. UNDERCLAY: A layer of clay lying immediately beneath a coal bed or carbonaceous shale. This layer may be bioturbated and indurated. Chiefly comprised of siliceous or aluminous clay capable of withstanding high temperatures without deformation, and may have a high shrink/swell potential. Technical Terms: The following are descriptions of basic terms utilized within the Rockfall Manual. The following listing is presented in alphabetical order. 1-Day Precipitation History: 3-Day Precipitation History: 15-Day Precipitation History: AADT: (Adjusted Annual Daily Traffic) Accident: ADT: (Average Daily Traffic) Aggregate Thickness: ASD: (Actual Sight Distance) ATT: (Average Truck Traffic) AVR: (Average Vehicle Risk) The recorded amount of precipitation, including but not limited to, rainfall, ice, or snow, during the previous 24 hour period (1 day) prior to the field work. The recorded amount of precipitation, including but not limited to, rainfall, ice, or snow, during the previous 36 hour period (3 day) prior to the field work. The recorded amount of precipitation, including but not limited to, rainfall, ice, or snow, during the previous 360 hour period (15 day) prior to the field work. Scaled adjustment of the annual daily traffic counts preformed within the field to account for increased traffic volume over time. An incident that resulted in an injury of loss of private property due to a rockfall event. The total amount of traffic, both truck and vehicle, for the given section of roadway over a 24-hour period. The summed total of the thicknesses of a specified rock type for the total height of the cut slope and/or natural slope. The shortest distance along a roadway over which a 6-inch object is continuously visible to a driver (assuming a height of 3.5 feet) The total amount of truck traffic for the given section of roadway over a 24-hour period. A scaled factor for the risk to a vehicle associated with potential rock fall calculated as: ADT * Slope Length (miles) / 24 Posted Speed Limit * 100% AVT: (Average Vehicle Traffic) The total amount of vehicle traffic for the given section of roadway over a 24-hour period. Bedding Plane: Break between the layering of sheet-like units, called laminations, beds or strata, indicating the change in lithology and/or physical characteristics.

84 Bench: Block Size: Cardinal Direction: Cleanout: Competent Bed: County Code A low angle, or flat, step excavated into the cut slope with higher angle slopes above or below. The rock size that dislodged from the cut slope to become a rockfall. Estimated or measured in cubic feet. The cardinal direction of travel is based on the roadway description (i.e., I-70, West/East or I-71, South/North) and not a site specific compass direction or bearing. By convention, roadways are considered to be oriented in a south to north or west to east direction. The removal of accumulated materials from ditches and benches including sediments and loose materials transported down slope from the cut slope face or natural slope. Rock strata composed of materials that are resistant to weathering processes relative to the underlying or overlying strata. The county that the site is located within using the ODOT three letter county designation. The county code consists of the first three letters of the county name with the exceptions of: County Ashland Ashtabula Champaign Harrison Meigs Monroe Montgomery Morgan Morrow Code ASD ATB CHP HAS MEG MOE MOT MRG MRW A full listing of the County Codes are included in Appendix X. Crop Line: The general term cropline, if not further defined, refers to the line along the ground surface where the mined mineral seam is exposed in the existing grade. The term cropline, with further definition, can also be utilized to define the structural contour of the top of the mined mineral seam which is covered by a uniform depth of overburden. Example: On some ODNR abandoned underground mine maps, the notation on a map line may read 30 foot cropline. This indicates the line on top on the mined mineral seam which was covered by 30 feet of natural overburden. Cut Slope: Cut Slope Angle: The constructed slope along the roadway created by removal of overburden and/or bedrock from the ground surface to the road grade. The angle from a horizontal datum/plane along the face of the constructed surface called the cut slope. (See Figure 1)

85 Cut Slope Height: Cut Slope Length: Ditch Depth: Ditch Width: Drift Entry: DSD: (Decision Site Distance) %DSD: (Percentage Decision Site Distance) Durable Rock: Field Team Flow Rate: Foreslope: Foreslope Angle: Gob: Ground Water: Haulage Shaft Joint: The vertical distance measured from the top of the cut slope to the base of the cut slope. (See Figure 1) The distance measured parallel along the road from which the material has been removed. The vertical distance from the bottom of the ditch to the top of the ditch at the roadway shoulder. (See Figure 1) The horizontal distance of the ditch from the top of the ditch at the roadway shoulder to ground surface projected as a horizontal plane.. A horizontal mine entry into the natural outcrop of the mined mineral seam. The required spacing along a roadway from which a driver has time to avoid an obstacle within the roadway. The value can be obtained from a design chart that considers speed limit, use of roadway, and possibly curvature and grade of the roadway. (Refer to Table 5 within the Manual Text) Ratio between the DSD and the ASD, calculated as %DSD = (ASD/DSD) * 100 Rock composed of materials that are resistant to weathering processes. Field personnel consisting of a geologist and an engineering geologist or a geotechnical engineer, who will complete the required field data collection for the rockfall inventory. Rate at which water is discharging from the ground surface in gallons per minute (gpm). The slope between the roadway shoulder and the bottom of the ditch. (See Figure 1) The angle of the slope between the roadway shoulder and the bottom of the ditch. (See Figure 1) Coal refuse commonly abandoned on the surface in piles at or near the mining operation. Flowing or non-flowing water discharging from the bedrock at the slope surface. A mine shaft utilized for the transportation of mined mineral to the ground surface. A discrete break or fracture within bedrock along which there has been little or no vertical displacement.

86 Joint Opening: Joint Spacing: JRC: Incompetent Bed: Infilling: Median: The open distance between the joint faces measured in inches. Distance between the centers of two joints (generally measured from center of joint opening to center of joint opening). Joint Roughness Coefficient; Method used to describe the roughness of the joint surface by using a comparison on the discontinuity surface profile with reference profile. Rock strata composed of materials that are not resistant to weathering processes. Deposition (clay, silt, sand, minerals, etc.) within the joint opening. Area located between lanes of opposite directions of traffic. The median can consist as a divided, concrete barrier or fence, or undivided, open grass. Mine Opening: Mine Subsidence: Mineralization: Natural Backslope: Natural Backslope Height: Orthogonal Joint Set: Potential Rockfall Size: Potential Rockfall Volume: Ritchie Criteria: Ritchie Score: A mine entry extending either vertically (shaft entry), horizontally (drift entry), or at an inclined angle (slope entry) to an underground mine. Sinking, settling or subsidence of the ground surface caused by the failed and collapse of the mine s roof support. The deposition of mineral deposits on a joint surface. The original ground surface located above the top of the excavated surface of the cut slope. (See Figure 1) The vertical distance from the top of the cut slope to the top of the natural ground surface, or to the upper limit of the source area for rockfall to occur within the Natural Backslope. (See Figure 1) Series of deep-seated regional joints created by tectonic stress, which have a general regional trend. The estimated dimensions of a potential rock size that may dislodge from the cut slope or natural backslope to become a rockfall based upon bedding, the spacing and orientation of joints, and undercutting within the cut slope. The estimated volume of material from a potential rockfall event that may dislodge from the cut slope or natural backslope to become a rockfall based upon the bedding, spacing and orientation of joints, and undercutting within the cut slope. Catchment design criteria based upon the slope height and slope angle geometry. A mathematical comparison of the Ritchie values compared to the actual ditch measurement. Ritchie Score = Ritchie Depth + Ritchie Width Actual Depth + Actual Width

87 Rock Quality Designation: (RQD) Rockfall: Rockfall Chute: The RQD value is the percentage of the length of a rock core run which is made up of continuous pieces of core sample, that are four (4) inches in length or greater. The detachment of rock mass(es) of variable size from along a cut slope or natural backslope with movement down slope toward the base of the slope. The clearing zone that results from the rockfall activities. Rockfall Debris: Rockfall Retention Device: Rockfall Volume: Route Classification: SDI: (Slake Durability Index) Seepage: Shaft: Shoulder: Site Number: SLM: (State Line Mile) Spring: Surface Deformation: Surface Water Flow: The accumulation of material as a result of rockfall from the slope. Devices installed on the cut slope, natural backslope, or near the slope base, that inhibits the further movement, reduces the energy of, or collects the debris from, the down slope movement or tries to controls the rockfall from entering onto the roadway. The amount of accumulation of the rockfall from the slope measure in cubic yards. State Route, US Route, or Interstate Route along which the field team will travel and complete the required inventory. Test for rock to determine its durability. Testing to be completed in accordance with ASTM D 4644: Standard Test Method for slake durability of shale and similar weak rocks. Non-flowing groundwater noted discharging from the slope surface measured in gallons per minute (gpm). A mine entry extending vertically from the ground surface down to the elevation of the mined interval. The graveled or paved area between the outside travel lane and the ditch. Designation number for each specific inventory site assigned by ODOT. Numerical designation of any point along an ODOT maintained roadway, based on the actual centerline mileage as measured from the western or southern county line or other true beginning. Flowing groundwater noted discharging from the slope surface measured in gallons per minute (gpm). Area(s) of surface settlement or subsidence. Deformation may be indicated by the presence of irregular drainage conditions. Area of flowing water along either the face of the cut slope or along the natural backslope. Generally, surface water flow will be in a down slope direction and accumulates within the ditch at the base of the slope.

88 Talus: Travel Lane or Lane: Troughing: Undercutting: Underground Mine: Valley Stress Relief Joint: The accumulated of weathered rock particles and soil along the cut slope, on benches, or at the foot of a slope. Paved section of roadway in which vehicular traffic moves. Linear surface deformation extending for some distance and having a gentle curvilinear profile when viewed in section. The natural removal of materials as a result of weathering out of an incompetent bed overlain by a competent bed resulting in an overhang. An underground excavation from which mineral resources were extracted. Steeply dipping to vertical fractures that are a result of stress relief accompanying valley formation. Typically, these joint sets are oriented parallel to or sub-parallel to the valley walls. Stress relief joints tend to attenuate with distance away from the valley walls.

89 Overburden Bench Natural Backslope Soil/Rock Interface Bench Natural Backslope Catchment Area Cut Slope Angle Cut Slope Height D Ditch Depth Foreslope/ Foreslope Angle Not To Scale APPENDIX FIGURE #1

90 APPENDIX B Criteria for Evaluation of Catchment

91 Appendix B Criteria for Evaluating Catchment Ditch Widths for Various Slope Angles Cut Slope Height, H (ft) >90*** Cut Slope Angle Catchment Ditch Width, W (ft) 2H:1V and 3H:1V Catchment Foreslope Angle* 0.25: min. 0.5: min. 1.0: /25** min. 1.5: /25** max. 4H:1V Catchment Foreslope Angle* 0.25:1 10/15** min. 0.5: min. 1.0:1 15/20** 20 20/25** 25/30** min. 1.5:1 15/20** 20 20/25** 25/30** max. 6H:1V Catchment Foreslope Angle* 0.25: min. 0.5: min. 1.0:1 25/30** 25/30** min. 1.5:1 25/30** 25/30** max. *If Slope under evaluation has a different foreslope angle than options listed above, round to nearest slope angle. **Single Angle Foreslope Catchment Ditch Width / Multi-Angle Foreslope (portion flat) Catchment Ditch Width *** Slopes with a height (H) greater than 90 feet should be evaulated with Appendix B width as minimum and adjusted according to specific site conditions For situations where the portion of the rock cut slope (backslope) intersecting the ditch is flatter than 1.5H:1V, use industry practices to evaluate width criteria.

92 APPENDIX C Field Parameters

93 APPENDIX C FIELD PARAMETERS BEDROCK HARDNESS CRITERIA Hardness Abbreviation Criteria - Field Very Soft VS Can be carved with a knife and excavated easily with a point of a pick. Can be readily scratched by fingernail and pieces 1-inch of more in thickness can be broken by finger pressure. Soft ST Can be grooved or gouged readily by a knife or pick. Can be excavated in small fragments by moderate blows of a pick point. Small, thin pieces can be broken by finger pressure. Medium Hard MH Can be grooved or gouged 0.05-inch deep by hand pressure of a geologist s pick. Hand specimens can be detached by moderate blows. Hard HD Can be scratched with a knife or pick Very Hard VH Cannot be scratched by a knife or sharp pick. Breaking of hand specimens require several hard blows of the geologist pick. Criteria Testing (Schmidt Hammer) BEDROCK BEDDING CRITERIA Bedding Type Abbreviation Criteria English Metric Thinly Laminated TL <0.125-in <3 mm Laminated LA in to in 3- to 10 mm Very Thinly Bedded VT to in 1.0- to 3.0 cm Thin Bedded TH to in 3.0- to 10.0 cm Medium Bedded MB to in to 30.0 cm Thick Bedded TK 1- to 3.3-ft to cm Massive Bedded MS >3.3-ft >1.0 m

94 WEATHERING CHARACTERISTICS Weathering Abbreviation Criteria Unweathered UW No evidence of any chemical or physical alteration of the rock mass. Slightly Weathered SW Slight discoloration on rock mass surface, slight alteration along discontinuities, less than 10% of the rock volume altered by either chemical or physical means. Moderately Weathered MW Discoloration evident across the majority of the rock mass, surface pitting and alteration penetrating well below the rock mass surface, weathering halos evident, 10-25% of the rock volume has been altered. Highly Weathered HW Entire rock mass discolored, alteration pervading nearly all of the rock mass surface with some pockets of slightly to moderately weathered rock noticeable, some materials may be leached away. Decomposed DE Rock reduced to a soil like state with relict tock texture evident, generally molded and crumbled by hand pressure. TEXTURE CHARACTERISTICS Primary Component Secondary Description Grain Diameter (metric mm) Grain Diameter (english - inch) Large >1025 >40.5 Boulder Medium Small Cobble Large Small Coarse Gravel Medium Fine Coarse Sand Medium Fine Very Fine Silt Clay --- <0.005 <0.0002

95 BEDROCK MODIFIERS* Modifier Definition Arenaceous Contains a sandy, or sandy-like appearance or texture. Arillaceous Contains silt and clay-sized particles. Calcareous Contains carbonate material as either a matrix or grains. Carbonaceous Contains an abundant amount of carbon material. Crystalline Contains crystalline grains or cementation composed of crystalline cement. Ferriferous Contains an abundance of iron rich minerals or grains. Fissile The rock mass has the ability to split along preferential planes. Friable The rock mass is easily crumbled, pulverized, or reduced. Micaceous Contains an abundance of mica grains within the rock mass. Pyritic Contains an abundance of pyrite nodules or crystals. Siliceous Contains an abundance of silica rich materials as either matrix or grains. Slickensided Contains polished striations indicating a plane along which differential movement has occurred. Stylolitic Contains irregular, suture-like contacts called stylolotes. Variegated The rock mass has a variety of colors, usually intermixed or streaked. Vuggy Contains cavities within the rock mass. * This listing is only of common modifiers and is not intended to be all inclusive. DISCONTINUITIES CHARACTERISTICS AND DESCRIPTION VARIABLE TABLE NUMBER Discontinuity Dip Angle NA Discontinuity Type C-1 Aperture C-2 Infilling Type C-3 Infilling Amount C-4 Infilling Profile C-5 Surface Roughness C-6 Spacing C-7

96 Type of Discontinuities Bedding Plane Valley Stress Relief Joint Orthogonal Joint Shear Fault Abbreviation BP VSRJ ORTH SH FT TABLE C-1 Characteristics A well defined planar surface that indicates a marked break in the deposition within sedimentary rocks. With in Ohio this is the major discontinuity type, which generally dip to the southeast at angles ranging from horizontal to 10º. Isolated areas can have dip angle nearing 30º in areas of stratigraphic pinchouts have been recorded. Steeply dipping to vertical fractures that are present near the valley walls that are a result of the stress relief associated with the valley formation. This type of joint attenuates across beds of differing strength and becomes less frequent with depth below the valley floor and distance away from the valley walls and are generally parallel to sub-parallel to the valley walls. Deep-seated regional joints created by tectonic stress that are more pervasive that the valley stress relief joints. A discontinuity along which differential movement has taken place parallel to the discontinuity surface, sufficient to produce slickensides. May be accompanied by a zone of fractured rock up to a few inches wide. Major discontinuity along which there has been an appreciable displacement and accompanied by gouge and/or a severe fractured zone within the rock mass. TABLE C-2 Type of Aperture Abbreviation Characteristics English (inches) Metric (mm) Wide WD Moderately Wide MW Narrow NW Very Narrow VN <0.005 <1 Tight TI

97 Type of Infilling Barite Clay Calcite Chlorite Iron Oxide Gypsum/Talc Healed Manganese None Pyrite Quartz Sand Silica Unknown TABLE C-3 Abbreviation Ba Cl Ca Ch Fe Gy Hd Mn No Py Qz Sd Si Uk TABLE C-4 Amount of Infilling Abbreviation Percentage of Infilling None No 0% Surface Stain Su 0-2% Spotty Sp 2-5% Partially Filled Pa 5-60% Filled Fi >60% Infilling Profile Planarity Wavy Planar Stepped Irregular TABLE C-5 Abbreviation F Wa Pl St Ir TABLE C-6 Surface Roughness Abbreviation Criteria Slickensided SLK Surface has a smooth, glassy finish with visual evidence of striations. Smooth SM Surface has a smooth appearance and feel. Slightly Rough Rough Very Rough SR RO VR Asperities on the discontinuity surface are distinguishable and can be felt. Some ridges and side-angle steeps are evident; asperities are clearly visible, and discontinuity surface feels very abrasive. Near-vertical steps and ridges occur on the discontinuity surface.

98 TABLE C-7 Type of Aperture Abbreviation Characteristics English (feet) Metric (m) Very Wide VW >10.0 >3 Wide W Moderately Wide MW Close C Very Close VC >0.2 <0.06 FIELD PARAMETERS FOR DETERMINING JRC From Hoek, et al., 1995

99 EXAMPLES OF DISCONTINUITIES TYPES Bedding Plane

100 Orthogonal Joint Valley Stress Relief Joint

101 EXAMPLES OF CATCHMENT TYPES Grueberg Fence with D-36 Barrier in front of Fence Grueberg Fence after rock catchment ODOT Mesh Fence

102 Soil Berm Open Catchment Area with Aggregate for Energy Dissipation Open Catchment Area

103 Open Catchment Area with Grouted Rip Rap D50 Concrete Wall with rock catchment D50 Wall with Flat Catchment Area

104 APPENDIX D Examples of Rockfall Tier Locations

105 TIER 1 EXAMPLES Minor overhangs of bedrock Slope Height = 15 ft BRO /- COMMENTS: Notice that the cut section has a relatively short back slope height and has weathered with minor overhangs that would result in small amounts of rockfall due to the slope angle. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur. It should be noted that the on the other side of the road is not a Tier 1 site, but a Tier 3 site. BRO /- COMMENTS: Notice that the cut section has a relatively short back slope height and has weathered with minor overhangs that would result in small amounts of rockfall due to the slope angle. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur.

106 HAM /- COMMENTS: Notice that the cut section has weathered with minor overhangs that would result in small amounts of rockfall due to the slope angle. HAM /- (Drainage Outfall) COMMENTS: Notice that durable layers of limestone are present within the slope. However, with the talus accumulation over the durable layer they no longer become an issue along the rock slope. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur.

107 HAM COMMENTS: Notice that the slope has weathered uniformly with no overhangs that would result in rockfall. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur. Minor overhangs of bedrock LIC /- COMMENTS: Notice that the slope has weathered uniformly with minimal overhangs that would result in rockfall. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur.

108 MUS /- COMMENTS: Notice that the slope has weathered uniformly with no overhangs that would result in rockfall. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur. SCI COMMENTS: Notice that the slope has weathered uniformly with no overhangs that would result in rockfall. Additionally, the ditch has adequate width and geometry to catch any rockfall that may occur.

109 TIER 2 EXAMPLES BRO /- COMMENTS: Notice that the slope has weathered relatively uniformly. However, overhangs that will result in rockfall are present throughout the slope including the along the slope crest. Additionally, the ditch width and geometry may be adequate to retain the rockfall from entering onto the roadway. It should be noted that the vegetation on the slope face will help reduce the rockfall energy resulting in less rocks reaching the roadway. Differential Weathering with overhang Rockfall block retained on slope GUE /- COMMENTS: Notice that the slope has not weathered uniformly. Differential weathering between the coal layer and the overlying sandstone layer has resulted in overhang rockfall. The ditch does not appear adequate to retain all rockfall from the roadway. A major portion of the sandstone blocks are not reaching the roadway, but are being retained on the highly weathered shale and coal layers within the lower portion of the slope.

110 Sandstone overhang within highly vegetated slope LIC /- COMMENTS: Notice that the lower slope has weathered relatively uniformly with little to no areas of overhang. However, within the upper vegetated slope a relatively thick to massive resistant sandstone layer has created an overhang that will result in rockfall. LIC /- COMMENTS: Notice that the slope has poorly weathered probably as a result of poor construction blasting that will result in rockfall. However, the ditch width appears to be adequate to retain any rockfall.

111 HAM COMMENTS: Notice that the slope has weathered relatively uniformly with overhangs that will result in rockfall. It should be noted that the shale bedrock has apparently weathered to residual soil that is failing resulting in minor slope instability. Rockfall being retained within the catchment area or by the D50 wall. HAM (D-50 Wall) COMMENTS: The catchment area and D50 concrete wall appears to be retaining the rockfall from entering onto the roadway.

112 52 ft 10 ft TUS /- COMMENTS: Notice that the slope has weathered relatively poorly with several sources of rockfall present. However, the 42 ft width of the catchment area appears to be adequate to retain any rockfall that may be produced prior to encroachment of the roadway. Well performing section of slope Highly weathered, poorly performing section(s) of slope Highly weathered, poorly performing section(s) of slope LIC /- COMMENTS: Notice that the majority of the slope has weathered relatively well. However, the upper and outer portions of the slope are highly weathered with several sources of rockfall present. However, the width of the ditch appears to be adequate to retain any rockfall that may be produced prior to encroachment of the roadway.

113 TIER 3 EXAMPLES ADA-52 COMMENTS: Notice that the slope has not weathered uniformly with overhangs present that will result in rockfall. It should be noted that a regional joint set is noticeable along which large blocks or volume of rockfall will occur in the future. Recent rockfall ` ADA-52 (Ditch line) COMMENTS: The catmint area appears to be only a hydraulic ditch, and does not appear to be adequate to retain a large rockfall that may occur from entering onto the roadway. It should be noted that the ditch line had been recently regarded and cleaned prior to photo.

114 ADA /- (looking East) Valley Stress Relief Joint Edge of Pavement ADA /- (looking West) COMMENTS: Notice that the slope has differential weathering resulting in an overhang of the massive sandstone that will result in rockfall. Additional, the ditch does not appear to be adequate to retain the large block size that will occur during the rockfall from entering onto the roadway. It should be noted that a regional joint set is noticeable along which large blocks of rockfall will occur in the future.

115 BEL /- Top of Cut Slope BEL Top of slope BEL Ditch COMMENTS: Notice that the slope has weathered poorly resulting in several sources that will result in rockfall. This includes the upper portion of the slope that is the natural backslope which is vegetated. Additional, the ditch dose not appears to be adequate to retain rockfall that will occur from entering onto the roadway.

116 BEL /- (Looking East) COMMENTS: Notice that the slope has not weathered uniformly with overhangs throughout the cut slope that will result in rockfall. BEL /- (Looking West) COMMENTS: Notice that the hydraulic ditch has been grouted rip rap to prevent erosion during high flow events. This reduces the effectiveness of the catchment area since the grout will allow for a better bounce of a block instead of diminishing the rockfall.

117 GUE /- Anticipated block size during a rockfall Differential weathering within the rock slope GUE /- COMMENTS: Notice that the slope has not weathered uniformly with overhangs at the top that will result in rockfall. Additional, it dose not appears that the ditch will be sufficient to retain the large blocks from the rockfall from entering onto the roadway. It should be noted that the where the highly weathered shale is present that a decrease in the rockfall reaching the ditch may occur.

118 HAM /- Rockfall from the cut back HAM /- COMMENTS: Notice that the slope has not weathered uniformly with overhangs at the top of the cut backslope that will result in rockfall. Additional, it dose not appears that there is any ditch to retain rockfall from entering onto the roadway. It should be noted that the retaining wall is only 3 to 4 inches higher than the toe of the slope and does not appear to be affective as a rockfall catchment structure.

119 Area(s) of rock overhang(s) TUS (Ramp C to SR 36) COMMENTS: Notice that the slope has not weathered uniformly with overhangs within the cut slope that will result in rockfall. Typical Block Size during Rockfall TUS (Ramp C to SR 36) COMMENTS: The catchment area does not appear adequate to retain all rockfall from the roadway. Note that several sizes of rock debris is evident within the catchment area.