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From page 4... ... A.1 LESSON SCHEDULE UNDERWATER FILTER INSTALLATION WORKSHOP Session Time Topic Part I Session 1 (20) Introduction to the workshop (Learning Outcomes) Read the entire page →
From page 5... ... A.2 UNDERWATER FILTER INSTALLATION WORKSHOP PART I LEARNING OUTCOMES 1. Describe the purpose, need, and functions of geotextile and granular filters 2. Read the entire page →
From page 6... ... A.3 UNDERWATER FILTER INSTALLATION LESSON PLAN Session Title: Underwater Filter Installation Workshop (Part I) Performance-Based Learning Outcomes: At the end of Part I, Participants will be able to: • Describe the purpose, need, and functions of geotextile and granular filters • Identify sources of design guidance for geotextile and granular filters • Discuss experience with and local agency guidance for installing filters underwater • Describe and list several techniques currently used to install filters underwater for typical armoring countermeasures (e.g., riprap, ACBs, etc.) Read the entire page →
From page 7... ... A.4 • The second Session of Part I begins with an Instructor-led discussion of local agency policy/experience/problems with placing filters underwater. Participants are asked "How would you go about installing a filter underwater and what guidance does your agency provide? Read the entire page →
From page 8... ... A.5 References Continued: NCHRP Report 593. "Countermeasures to Protect Bridge Piers from Scour," Transportation Research Board, 2007. Read the entire page →
From page 9... ... A.6 LEARNING OUTCOMES (PART I) • Describe the purpose, need, and functions of geotextile and granular filters. Read the entire page →
From page 10... ... A.7 TYPES OF FILTERS • Filters can be a geotextile, a layer of granular material, or a combination of both • Granular filters can be composed of multiple layers (e.g., a finer layer next to the soil, and a coarser layer on top of the fine layer) I-2 Key Message: Characteristics of granular and geotextile filters Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: Tell: The general characteristics of granular and geotextile filters. Read the entire page →
From page 11... ... A.8 I-3 Key Message: Illustrate granular, geotextile, and composite filters. Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: See Slide I-2 Notes: Some situations may require a composite filter with a granular transition layer under the geotextile. Read the entire page →
From page 12... ... A.9 I-4 Key Message: Schematic diagram of a typical granular filter beneath riprap. Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: See Slide I-2 Tell: Point out relationship between the riprap armor layer, the underlying granular filter, and the base soil. Read the entire page →
From page 13... ... A.10 Geotextile filter beneath armor layer I-5 Key Message: Geotextile filter beneath articulating concrete blocks. Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: See Slide I-2 Tell: Point out relationship between the ACB armor layer and the geotextile filter placed on the prepared surface of the base soil. Read the entire page →
From page 14... ... A.11 FUNCTIONS THAT FILTERS PERFORM • During floods, the flow is very turbulent. • A filter provides a barrier between the turbulence and the fine particles of the native soil. Read the entire page →
From page 15... ... A.12 I-7 Key Message: Seepage gradients for normal (baseflow) conditions. Read the entire page →
From page 16... ... A.13 I-8 Key Message: Seepage gradients during flood peak conditions. Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: See Slide I-6 Tell: During flood conditions high water in the channel drives seepage into the stream banks, raising the groundwater level. Read the entire page →
From page 17... ... A.14 I-9 Key Message: Seepage gradients after flood recession. Background Information: HEC-23, Volume 2, Design Guideline 16 Instructional Method: See Slide I-6 Tell: • After flood waters recede, high seepage gradients develop as groundwater returns to the channel. Read the entire page →
From page 18... ... A.15 SOURCES OF FILTER DESIGN GUIDANCE • FHWA Hydraulic Engineering Circular HEC-23 "Bridge Scour and Stream Instability Countermeasures: Experience, Selection, and Design Guidance" Third Edition, Volumes 1 and 2, 2009. • NCHRP Report 568 "Riprap Design Criteria, Recommended Specifications, and Quality Control," 2006. Read the entire page →
From page 19... ... A.16 INSTALLING FILTERS UNDERWATER – LOCAL EXPERIENCE • What techniques are used locally for installing filters underwater? • What guidance is provided by your agency for the installation of filters underwater? Read the entire page →
From page 20... ... A.17 INSTALLATION OF FILTER SYSTEMS UNDERWATER - EUROPEAN PRACTICE • Traditional techniques – fascine mattresses • Mechanized devices and equipment • A sandmat • Geotextile containers • Contractor concepts and practice I-12 Key Message: Some traditional techniques for underwater filter installation such as fascines are still in use in Europe. However, in recent years the technology has become increasingly mechanized and sophisticated. Read the entire page →
From page 21... ... A.18 FASCINE MATTRESSES • Used in Europe for 100's of years • Used today in Germany, Netherlands, and UK • Also known as "sinker mat" • Effective but labor intensive I-13 Key Message: 1998 Scanning Review of European practice found that fascines are still considered an effective means of getting a filter underwater in many European countries. Background Information: NCHRP Report 887. Read the entire page →
From page 22... ... A.19 I-14 Key Message: Overall view of fascine mattress being constructed in Germany in 2001. Background Information: NCHRP Report 887 "Guidance for Underwater Installation of Filter Systems for Scour and Other Erosion Countermeasures," 2018. Read the entire page →
From page 23... ... A.20 I-15 Key Message: Close up view of fascine mattress being constructed in Germany in 2001. Background Information: NCHRP Report 887. Read the entire page →
From page 24... ... A.21 MECHANICAL TECHNIQUES I-16 Key Message: Roller for placing geotextile onto subgrade. Background Information: NCHRP Report 887. Read the entire page →
From page 25... ... A.22 MECHANICAL TECHNIQUES I-17 Key Message: Flexible revetment with integrated geotextile filter ready to be placed under water with a lifting frame. Background Information: NCHRP Report 887. Read the entire page →
From page 26... ... A.23 THE SANDMAT I-18 Key Message: The sandmat was developed to overcome many problems commonly encountered when placing geotextiles underwater. Background Information: NCHRP Report 887. Read the entire page →
From page 27... ... A.24 Notes: Placing geotextiles under water is problematic for a number of reasons: • Most geotextiles that are used as filters beneath riprap are made of polyethylene or polypropylene. • These materials have specific gravities ranging from 0.90 to 0.96, meaning that they will float unless weighted down or otherwise anchored to the subgrade prior to placement of the armor layer. Read the entire page →
From page 28... ... A.25 THE SANDMAT I-19 Key Message: The sandmat was developed to overcome many problems commonly encountered when placing geotextiles underwater. Background Information: NCHRP Report 887. Read the entire page →
From page 29... ... A.26 GEOTEXTILE CONTAINERS I-20 Key Message: In deep water or in currents greater than 3.3 ft/s (1 m/s) , German practice calls for the use of sand-filled geotextile containers. Read the entire page →
From page 30... ... A.27 GEOTEXTILE CONTAINERS I-21 Key Message: In deep water or in currents greater than 3.3 ft/s (1 m/s) , German practice calls for the use of sand-filled geotextile containers. Read the entire page →
From page 31... ... A.28 PLACING GEOTEXTILE CONTAINERS I-22 Key Message: Handling, filling and, closing of geotextile containers at the "Eidersperrwerk" storm surge barrier off the North Sea coast of Germany. Background Information: NCHRP Report 887. Read the entire page →
From page 32... ... A.29 PLACING GEOTEXTILE CONTAINERS I-23 Key Message: Installation of scour stabilization by the use of a stone dumping barge/vessel at the "Eidersperrwerk" storm surge barrier off the North Sea coast of Germany. Background Information: NCHRP Report 887. Read the entire page →
From page 33... ... A.30 CONTRACTOR CONCEPTS AND PRACTICE I-24 Key Message: GEOfabrics of the United Kingdom (a geotextile manufacturer) provides installation concepts for installing geotextiles underwater in coastal and river applications. Read the entire page →
From page 34... ... A.31 CONTRACTOR CONCEPTS AND PRACTICE I-25 Key Message: GEOfabrics of the United Kingdom (a geotextile manufacturer) provides installation concepts for installing geotextiles underwater in coastal and river applications. Read the entire page →
From page 35... ... A.32 INSTALLATION OF FILTER SYSTEMS UNDERWATER - U.S. PRACTICE • Problems with placing granular filters underwater and issues/questions on the use of geotextile filters noted in the 1980's • NCHRP Projects and 1998 Scanning Review of European practice • Development of guidance for using geotextile containers I-26 Key Message: Since the 1980s in the U.S. Read the entire page →
From page 36... ... A.33 USACOE INVESTIGATION OF THE USE OF GEOTEXTILES AS A FILTER FOR REVETMENT APPLICATIONS (1967-1972) Problem areas identified: • Erosion under the fabric - small voids and loose fill areas are generally bridged by filter fabric, providing a site for potential erosion. Read the entire page →
From page 37... ... A.34 1998 SCANNING REVIEW OF EUROPEAN PRACTICE AND NCHRP PROJECTS • European Practice for Bridge Scour and Stream Instability Countermeasures • Sponsored by TRB, NCHRP and FHWA • NCHRP Projects 24-07(1 & 2) to investigate and improve guidance for the installation of pier scour countermeasures I-28 Key Message: Following the Scanning Review NCHRP projects were initiated to improve guidance in the U.S. Read the entire page →
From page 38... ... A.35 LABORATORY TESTING OF GEOTEXTILE CONTAINERS FOR UNDERWATER FILTER PLACEMENT • For the geotextile containers testing at prototype scale was, primarily, to demonstrate constructability in flowing water and performance in high velocity flow conditions. • Tests confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment (in the U.S.) Read the entire page →
From page 39... ... A.36 LABORATORY SETUP FLOW 9 m PLAN VIEW 6 m 1.5m 0.5m Pier PROFILE Pier Riprap Sand-filled geotextile containers 0.4m 0.5m/s Sand Concrete Concrete I-30 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887. Read the entire page →
From page 40... ... A.37 I-31 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887. Read the entire page →
From page 41... ... A.38 I-32 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887. Read the entire page →
From page 42... ... A.39 I-33 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887. Read the entire page →
From page 43... ... A.40 I-34 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887 "Guidance for Underwater Installation of Filter Systems for Scour and Other Erosion Countermeasures," 2018. Read the entire page →
From page 44... ... A.41 I-35 Key Message: Laboratory testing confirmed that geotextile containers can be fabricated locally and that the containers and riprap can be placed in flowing water with standard commercially available equipment in the U.S. Background Information: NCHRP Report 887. Read the entire page →
From page 45... ... A.42 SUMMARY EXERCISE Based on your experience and local conditions, rate the following techniques for practicality and adaptability for placing a filter underwater (use a scale of 0 (worst) to 10 (best) Read the entire page →
From page 46... ... A.43 LEARNING OUTCOME (PART I, SESSION 3) • Session 3 consists of a case study which will highlight the application of geocontainers and the use of a geotextile filter attached to prefabricated armor units on a scour critical tidal inlet bridge in North Carolina (NCDOT) Read the entire page →
From page 47... ... A.44 BONNER BRIDGE OVER OREGON INLET, NC I-38 Key Message: NCDOT determined based on an October 2013 side scan survey that the 2.5 mile long Bonner Bridge over the Oregon Inlet had reached a scour critical condition at one of the mid-span bents. Background Information: • NCHRP Report 887. Read the entire page →
From page 48... ... A.45 • In addition, a second element of danger loomed over the only highway connection to the North Carolina Outer Banks. It was possible that a major low pressure system centered over the Midwest would race east, stall off shore, and set up a major nor'easter in the next four or five days. Read the entire page →
From page 49... ... A.46 BONNER BRIDGE OVER OREGON INLET, NC I-39 Key Message: The Bonner Bridge was constructed in 1963 replacing ferry service to Hatteras Island. The coastal geology of the site required the bridge to be founded on friction piles in deep sand. Read the entire page →
From page 50... ... A.47 Instructional Method: Tell: • Structural decay and scour have long plagued the bridge. The Bonner Bridge has been identified as scour critical and a comprehensive and aggressive monitoring plan was instituted. Read the entire page →
From page 51... ... A.48 BONNER BRIDGE Bent #166 I-40 Key Message: NCDOT formulated a three phase strategy for structural countermeasure response. The strategy addressed immediate action to stabilize the scour, intermediate countermeasure installation, and long term integrity of Bent 166. Read the entire page →
From page 52... ... A.49 2. The intermediate action would stack three tiers of A-Jacks® prefabricated concrete armor units to form a perimeter around Bent 166. Read the entire page →
From page 53... ... A.50 USACOE DREDGE AND FILL AT BENT #166 I-41 Key Message: USACOE dredge and fill provided an immediate (short term) correction for the scour critical problem at Bent #166. Read the entire page →
From page 54... ... A.51 • December 6th: Great Lakes Dredge & Dock begins relocating 2,000 ft of 36-inch diameter discharge line from the beach disposal site to the vicinity of Bent 166. The ALASKA would work around the clock (weather permitting) Read the entire page →
From page 55... ... A.52 I-42 Key Message: Geotextile container stockpile (4'x4'x4' cubes) at Bonner Bridge. Read the entire page →
From page 56... ... A.53 I-43 Key Message: Pallets of 4' A-Jacks® (3 jacks per pallet) at Bonner Bridge assembly area. Read the entire page →
From page 57... ... A.54 Assembly area Stockpile of assembled A-Jacks® I-44 Key Message: A-Jacks® assembly and stockpile at Bonner Bridge. Background Information: • NCHRP Report 887. Read the entire page →
From page 58... ... A.55 I-45 Key Message: Stainless steel cable and hardware binding A-Jacks® elements into modules or "logs" for placement. Background Information: • NCHRP Report 887. Read the entire page →
From page 59... ... A.56 I-46 Key Message: A-Jacks® modules placed on barge for transport to bridge. Background Information: • NCHRP Report 887. Read the entire page →
From page 60... ... A.57 I-47 Key Message: Close up of Contractor's I-beam and cable assembly for lifting and placing A-Jacks® modules. Background Information: • NCHRP Report 887. Read the entire page →
From page 61... ... A.58 I-48 Key Message: Geotextile filter applied to the base of each A-Jacks® module. Background Information: • NCHRP Report 887. Read the entire page →
From page 62... ... A.59 I-49 Key Message: With the A-Jacks® perimeter established, 3 ft cube and 4 ft cube sand filled geotextile containers were placed between the Bent #166 piles and within the battered pile cluster. Background Information: • NCHRP Report 887. Read the entire page →
From page 63... ... A.60 I-50 Key Message: Loading the sand filled geotextile containers from the assembly area to a barge for transport to the bridge site. Background Information: • NCHRP Report 887. Read the entire page →
From page 64... ... A.61 SUMMARY EXERCISE Based on this case study and the material presented in Sessions 1 and 2, be prepared to list and discuss the Lessons Learned from this recent underwater filter installation project. I-51 Key Message: "What do you think are the key lessons from NCDOT's experience with the Bonner Bridge project? Read the entire page →
From page 65... ... A.62 • As time allows make the following points (see the Henderson 2014 article referenced above) Read the entire page →
From page 66... ... A.63 SUMMARY OF LESSONS LEARNED • Fastening the geotextile filter to a prefabricated armoring system provides an effective approach to installing a filter in deep water under adverse conditions. Read the entire page →
From page 67... ... A.64 ADDITIONAL LESSONS LEARNED • Establishing NCDOT internal coordination including chains of command and communication was a key to success. • Advanced planning and drills promoted by the NC FHWA Division facilitated implementation of the emergency plan of action. Read the entire page →
From page 69... ... A.66 UNDERWATER FILTER INSTALLATION LESSON PLAN Session Title: Underwater Filter Installation Workshop (Part II) PerformanceBased Learning Outcomes: At the end of Part II, Participants will be able to: • Describe, evaluate, and list in order of priority (based on local conditions) Read the entire page →
From page 70... ... A.67 UNDERWATER FILTER INSTALLATION LESSON PLAN 2. Instructor introduces the objectives of the workshop assignments which are to evaluate and develop techniques and approaches for installing an appropriate filter and overlying riprap armor for a scour critical bridge on the Snake River in Idaho. Read the entire page →
From page 71... ... A.68 UNDERWATER FILTER INSTALLATION LESSON PLAN (2) Identify and list equipment needs (no cost limit) Read the entire page →
From page 72... ... A.69 UNDERWATER FILTER INSTALLATION LESSON PLAN References: FHWA Hydraulic Engineering Circular HEC-23 "Bridge Scour and Stream Instability Countermeasures: Experience, Selection, and Design Guidance" Third Edition, Volumes 1 and 2, 2009. NCHRP Report 568 "Riprap Design Criteria, Recommended Specifications, and Quality Control," Transportation Research Board, 2006. Read the entire page →
From page 73... ... A.70 LEARNING OUTCOMES (PART II) • Describe, evaluate, and list in order of priority (based on local conditions) Read the entire page →
From page 74... ... A.71 LABORATORY TESTING OF FILTER INSTALLATION Diver assisted installation of granular and geotextile filters in prototype scale laboratory flume. • Geotextile filters: -Buoyant, non-woven geotextile sheets unrolled in direction of flow. Read the entire page →
From page 75... ... A.72 LABORATORY TESTING FACILITY II-3 Key Message: Views of the testing facility and divers in the water. Background Information: NCHRP Report 887. Read the entire page →
From page 76... ... A.73 BUOYANT vs. SELF-SINKING FILTER FABRICS II-4 Key Message: Successful installation of buoyant and self-sinking filter fabrics at 0.6 ft/s velocity. Read the entire page →
From page 77... ... A.74 BUOYANT vs. SELF-SINKING FILTER FABRICS II-5 Key Message: Problematic installation of buoyant and self-sinking filter fabrics at 3.5 feet per second velocity. Read the entire page →
From page 78... ... A.75 COMPOSITE (GEOBAG) FILTER FILLED WITH FLEXIBLE TREMIE UNDERWATER II-6 Key Message: Diver installation of a composite filter consisting of empty geobags placed at the pier and filled with granular filter material using a flexible tremie hose. Read the entire page →
From page 79... ... A.76 COMPOSITE (GEOBAG) FILTER FILLED WITH FLEXIBLE TREMIE UNDERWATER II-7 Key Message: Diver installation of loose pea gravel and filling of in place empty geobags at the pier and filled using a flexible tremie hose. Read the entire page →
From page 80... ... A.77 DISPERSION AND SEGREGATION ISSUES WITH PLACING GRANULAR FILTER MATERIAL IN FLOWING WATER • When placed in flowing water, granular filter materials will disperse and segregate unless placed directly on the bed. • To quantify the effect of dispersion while dropping granular filter material through the water column, a well-graded mixture of sand and pea gravel was placed at various heights above the bed in 4 feet of flowing water using a 2-inch diameter rigid tremie pipe. Read the entire page →
From page 81... ... A.78 DISPERSION AND SEGREGATION ISSUES WITH PLACING GRANULAR FILTER MATERIAL IN FLOWING WATER II-9 Key Message: Investigation of dispersion and segregation issues when attempting to place granular filter material in flowing water. Background Information: NCHRP Report 887. Read the entire page →
From page 82... ... A.79 DISPERSION AND SEGREGATION ISSUES WITH PLACING GRANULAR FILTER MATERIAL IN FLOWING WATER II-10 Key Message: Variations in resulting in place grain size distributions when placed with a rigid tremie pipe at various elevations above the bed (approach velocity of 1.0 ft/s) Read the entire page →
From page 83... ... A.80 LESSONS LEARNED FROM UNDERWATER TESTING OF FILTER INSTALLATION TECHNIQUES • The practical limit for buoyant geotextile placement by divers was roughly 2.5 ft/s. Placing a self-sinking fabric was barely manageable at an approach velocity of approximately 3.5 ft/s. Read the entire page →
From page 84... ... A.81 • It should be noted that safety precautions were taken during all phases of the installation demonstration tests. Divers were tethered at all times, and maintained constant communication with the topside line handler. Read the entire page →
From page 85... ... A.82 GUIDELINES FOR PLACING GRANULAR FILTERS UNDERWATER – INSTALLATION • Underwater installation of granular filters can be performed by clamshell bucket or tremie, with the filter material being released on or very near the bed. • The tremie method of placement can employ a rigid pipe from the surface or a flexible hose through which the filter material is pumped in a water slurry to divers at the end of the hose. Read the entire page →
From page 86... ... A.83 GUIDELINES FOR PLACING GRANULAR FILTERS UNDERWATER – INSPECTION AND MAINTENANCE • Immediately after placing the granular filter, and before the armor layer is installed, the filter should be inspected for adequate thickness and areal coverage. • If the granular filter layer is not thick enough, or is spotty in places, additional material must be added before placing the armor. Read the entire page →
From page 87... ... A.84 GUIDELINES FOR PLACING GRANULAR FILTERS UNDERWATER – QUALITY ASSURANCE Quality assurance measures for the design and installation of granular filters underwater include: 1. Filter design per established procedures (e.g. Read the entire page →
From page 88... ... A.85 GUIDELINES FOR PLACING GRANULAR FILTERS UNDERWATER – QUALITY CONTROL Quality control measures for the design and installation of granular filters underwater include: 1. Check that contractor's submittals for material quality testing and size gradation conform with project specifications. Read the entire page →
From page 89... ... A.86 • Vcrit is the velocity for the threshold of motion for the d50 (median) size particle of the filter gradation. Read the entire page →
From page 90... ... A.87 GUIDELINES FOR PLACING GEOTEXTILE FILTERS UNDERWATER – INSTALLATION OF GEOTEXTILE SHEETS • In general, the geotextiles should be placed so that they are free of folds and wrinkles and lie in intimate contact with the subgrade. • Individual sheets should be overlapped a minimum of 12 inches and temporarily weighed down before the armor is placed. Read the entire page →
From page 91... ... A.88 GUIDELINES FOR PLACING GEOTEXTILE FILTERS UNDERWATER – INSTALLATION OF GEOBAGS • Geotextile filters can also be installed as bags filled with sand or gravel filter material. • Geotextile containers can be filled prior to placement, sewn shut, and dropped through the water column. Read the entire page →
From page 92... ... A.89 GUIDELINES FOR PLACING GEOTEXTILE FILTERS UNDERWATER – INSPECTION AND MAINTENANCE • Immediately after placing the geotextile filter, and before the armor layer is installed, the filter should be inspected for sufficient areal coverage and overlaps. • When geotextile containers or geobags are used, they must be inspected to ensure that appropriate overlap has been achieved and no voids or bare spots exist in the filter layer. Read the entire page →
From page 93... ... A.90 GUIDELINES FOR PLACING GEOTEXTILE FILTERS UNDERWATER – QUALITY ASSURANCE Quality assurance measures for the design and installation of geotextile filters underwater include: 1. Filter design methods per established procedures (e.g. Read the entire page →
From page 94... ... A.91 • Specifications - The recommended specification for geotextiles is AASHTO M288. It covers six geotextile applications and provides materials specifications and construction/installation guidelines for geotextiles in highway applications. Read the entire page →
From page 95... ... A.92 GUIDELINES FOR PLACING GEOTEXTILE FILTERS UNDERWATER – QUALITY CONTROL Quality control measures for the design and installation of geotextile filters underwater include: 1. Check contractor's submittals for material quality testing in conformance with project specifications. Read the entire page →
From page 96... ... A.93 • The use of divers should be performed with all applicable dive safety precautions, including tethers, underwater and topside communications, and buffer distance from equipment and machinery. Notes: N/A Read the entire page →
From page 97... ... A.94 CONCLUSIONS FROM NCHRP PROJECT 24-42 • A survey of practitioners across the U.S. revealed that some underwater installation practices in other countries are still new and largely untried in the U.S. Read the entire page →
From page 98... ... A.95 CONCLUSIONS FROM NCHRP PROJECT 24-42 • Practitioners in the U.S. indicated that underwater inspection of a filter installation is not usually required prior to placing the armor layer on top. Read the entire page →
From page 99... ... A.96 SUMMARY EXERCISE Based on your experience and local conditions, rate the following techniques for practicality and adaptability for placing a filter underwater. Use a scale of 0 (worst) Read the entire page →
From page 100... ... A.97 LEARNING OUTCOMES (PART II, SESSION 2) • Session 2 consists of a Group Workshop to develop installation techniques and discuss solutions for a typical underwater filter installation project at a riverine bridge. Read the entire page →
From page 101... ... A.98 TEAM ORGANIZATION FOR SESSION 2 • You will work as teams from a DOT Hydraulics Section to develop installation techniques for underwater filter and riprap armor installation at a typical riverine bridge. • Group(s) Read the entire page →
From page 102... ... A.99 ASSIGNED TASKS 1. Develop a conceptual plan for underwater installation of the assigned filter and riprap armor 2. Read the entire page →
From page 103... ... A.100 SITE LOCATION MAP II-27 Key Message: Map of Ferry Butte Road bridge site. Background Information: Map from USGS website. Read the entire page →
From page 104... ... A.101 AERIAL PHOTOGRAPH II-28 Key Message: Aerial photograph of bridge site. Background Information: Photograph from Google Earth. Read the entire page →
From page 105... ... A.102 BRIDGE (flow is from left to right) II-29 Key Message: Detailed view of bridge site. Read the entire page →
From page 106... ... A.103 BRIDGE PLAN AND PROFILE II-30 Key Message: Bridge plan and profile. Background Information: Bridge plans from ITD were used to develop the scour countermeasure design. Read the entire page →
From page 107... ... A.104 DIVE TEAM ON SITE II-31 Key Message: DOT dive team on site. Background Information: A dive team was used to determine the condition of the piers, type of bed material, and debris/obstructions prior to the countermeasure design. Read the entire page →
From page 108... ... A.105 CONDITIONS AT BASE OF PIERS II-32 Key Message: Stream bed conditions at typical bridge pier. Background Information: Photograph by ITD shows logs and other debris at the base of the piers. Read the entire page →
From page 109... ... A.106 WORKSHOP HANDOUT • Group 1 will develop a plan to install a granular filter beneath a riprap armor layer. • Group 2 will develop a plan to install a geotextile filter beneath a riprap armor layer. Read the entire page →
From page 110... ... A.107 IDAHO TRANSPORTATION DEPARTMENT'S APPROACH • A-Jacks® armor systems with underlying geotextile filters were installed by ITD on two bridges on the Snake River. • News Release: "Pocatello – A process used to prevent erosion from the base of bridge piers will be used for the first time in Idaho to control "scouring" on two eastern Idaho bridges that were severely damaged in the 1997 Snake River Flood." II-34 Key Message: The ITD's solution Background Information: NCHRP Report 887. Read the entire page →
From page 111... ... A.108 SELECTION OF THE SCOUR COUNTERMEASURE • Idaho Department of Natural Resources (DNR) rejected the ITD proposal to fill the scour holes with clean washed gravel prior to placing a countermeasure. Read the entire page →
From page 112... ... A.109 ITD SITE PREPARATION • Woody debris removed from scour protection zones. • Boulders projecting 400 mm (16 inches) Read the entire page →
From page 113... ... A.110 ASSEMBLY OF THE A-JACKS® II-37 Key Message: Preparation and assembly of the A-Jacks®. Background Information: NCHRP Report 887. Read the entire page →
From page 114... ... A.111 CONTRACTOR'S LIFTING FRAME FOR THE A-JACKS® II-38 Key Message: Contractor's lifting frame for the A-Jacks®. Background Information: NCHRP Report 887. Read the entire page →
From page 115... ... A.112 APPLYING THE GEOTEXTILE TO THE A-JACKS® II-39 Key Message: Adding the geotextile filter to the A-Jacks®. Background Information: NCHRP Report 887. Read the entire page →
From page 116... ... A.113 HANDLING DEVICE TO PLACE THE A-JACKS® II-40 Key Message: Contractor designed handling device to place the A-Jacks® underwater. Background Information: NCHRP Report 887. Read the entire page →
From page 117... ... A.114 PLACING THE A-JACKS® AT FERRY BUTTE BRIDGE II-41 Key Message: Overview of placing operation for A-Jacks® modules at the Ferry Butte Bridge. Background Information: NCHRP Report 887. Read the entire page →
From page 118... ... A.115 DIVERS ASSISTING PLACING THE A-JACKS® II-42 Key Message: Divers assisting placing the A-Jacks® modules at the Ferry Butte Bridge. Background Information: NCHRP Report 887. Read the entire page →
From page 119... ... A.116 ITD REQUIREMENTS AND SPECIFICATIONS • Fit modules as close as possible between one another and to pier structure. • Manufacturer requested that geotextile be applied to modules prior to placement. Read the entire page →
From page 120... ... A.117 DIVER VERIFICATION OF FINAL INSTALLATION II-44 Key Message: Divers inspecting placement of the A-Jacks® modules at the Ferry Butte Bridge. Background Information: NCHRP Report 887. Read the entire page →
From page 121... ... HO1.1 Group #1 Handout Underwater Filter Installation Workshop 1. Problem Statement The Ferry Butte Bridge crosses the Snake River between Blackfoot, ID and the American Falls Reservoir in southeastern Idaho. Read the entire page →
From page 122... ... HO1.2 Ferry Butte Rd Bridge N0 3 6 miles Blackfoot American Falls Reservoir Project site Figure 1. Snake River project site in southeastern Idaho (image courtesy USGS) Read the entire page →
From page 123... ... HO1.3 Figure 3. Ferry Butte Road Bridge. Read the entire page →
From page 124... ... HO1.4 Figure 5. Dive team on site at Ferry Butte Road Bridge. Read the entire page →
From page 125... ... HO1.5 Research of the bridge data files also produced pertinent hydraulic data, bridge geometry, and bed material characteristics from a previous Bridge Hydraulics Report (BHR) Read the entire page →
From page 126... ... HO1.6 Based on bed material characteristics, typical construction season flows, and 50-year flood design flow, you estimate that the following granular filter requirements and riprap sizing will be required: Granular filter requirements (to be placed at low flow) : • Filter gradation: D85 = 21 mm ( 0.8 in.) Read the entire page →
From page 127... ... HO1.7 3. Group 1 Assignment Based on the information provided above, your team assignment for the next 30 minutes is to evaluate the feasibility of protecting the Ferry Butte bridge piers with a granular filter/riprap armor countermeasure and develop underwater installation techniques to support this alternative. Read the entire page →
From page 128... ... HO1.8 4. Describe, step by step, the procedures for filter installation underwater (provide sketches of your approach, as necessary) Read the entire page →
From page 129... ... HO2.1 Group #2 Handout Underwater Filter Installation Workshop 1. Problem Statement The Ferry Butte Bridge crosses the Snake River between Blackfoot, ID and the American Falls Reservoir in southeastern Idaho. Read the entire page →
From page 130... ... HO2.2 Ferry Butte Rd Bridge N0 3 6 miles Blackfoot American Falls Reservoir Project site Figure 1. Snake River project site in southeastern Idaho (image courtesy USGS) Read the entire page →
From page 131... ... HO2.3 Figure 3. Ferry Butte Road Bridge. Read the entire page →
From page 132... ... HO2.4 Figure 5. Dive team on site at Ferry Butte Road Bridge. Read the entire page →
From page 133... ... HO2.5 Research of the bridge data files also produced pertinent hydraulic data, bridge geometry, and bed material characteristics from a previous BHR. (Note: Characteristics and conditions at this bridge have been altered for instructional purposes.) Read the entire page →
From page 134... ... HO2.6 Based on bed material characteristics, typical construction season flows, and 50-year flood design flow, you estimate that the following geotextile filter requirements and riprap sizing will be required: Geotextile filter requirements (to be placed at low flow) : Using the base soil (bed material) Read the entire page →
From page 135... ... HO2.7 Subgrade preparation for filter and riprap installation: The spread footings at the piers are 6.5 to 9 feet below the present riverbed elevation, but will become exposed and undermined due to scour during flood events. Mounding the riprap on top of the riverbed is not acceptable for many reasons; therefore, the bed must be excavated such that the top of the riprap is flush with the ambient riverbed elevation. Read the entire page →
From page 136... ... HO2.8 4. Describe, step by step, the procedures for filter installation underwater (provide sketches of your approach, as necessary) Read the entire page →
From page 137... ... HO2.9 7. After 30 minutes a designated spokesperson from your team should be prepared to present your team's observations, analysis, and approach to installing your assigned underwater filter/armor pier protection countermeasure at a typical pier of the Ferry Butte Road Bridge. Read the entire page →

From page 4...

... A.1 LESSON SCHEDULE UNDERWATER FILTER INSTALLATION WORKSHOP Session Time Topic Part I Session 1 (20) Introduction to the workshop (Learning Outcomes)