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23 Feb 2012

REPORT OF LANDSLIDE


The followings is an example report to be prepared by civil  engineer  on the slope failure cases.  


Project :  KEGAGALAN CERUN DI KM 44, JALAN SIMPANG PULAI-CAMERON HIGHLANDS ( GUNUNG PASS ) PAHANG


1.0        Introduction

The Simpang Pulai – Cameron Highlands road is part of the highway connecting Simpang Pulai in the state of Perak to Kuala Berang in the state of Terengganu. A significant and large landslide began in September 2003 in a newly-cut slope in the mountainous region located at the 44th kilometer stretch of the Simpang Pulai – Cameron Highlands road.This portion of the road is also known as Gunung Pass.


Generally, the geology of the Gunung Pass ( Mount Pass ) area consists of a sequence of metasedimentary rocks, which are confined within a 4 km stretch. They are highly deformed and faulted, and have undergone low to medium-grade dynamic metamorphism. The original sedimentary rocks are thought to have been deposited during the Ordovician age, deformed and metamorphosed during the late Palaeozoic age. The metasedimentary rocks have been intruded by granite plutons that are predominantly Permian to Jurassic in age. The exposed rock found on the cut slopes at the site include, in order of abundance: quartz mica schist, graphite schist, quartzite and phyllite with a weathering grade that varies from grade II (slightly weathered) to grade IV (completely weathered). Grade VI (residual soils) materials are only confined to the top most section of the slope, and their estimated thickness varies between 3-6m.

Kumpulan IKRAM Sdn Bhd (Contractor) was issued a Letter of Intent on 30.05.2008 to carry out deep boring works to determine the slip surface depth of landslide at the KM 44 Simpang Pulai – Cameron Highlands road.  
Kumpulan IKRAM Sdn Bhd. is required to assess the location or depth of slip surface of the landslide at the KM44, Simpang Pulai – Cameron Highlands road and to formulate a work scope that will meet the following objective and budgetary constraints of the works.

2.0        Objective of the Study

The primary objective of the study is to provide the Government of Malaysia with the location or depth of slip surface of the landslide at the KM 44, Simpang Pulai – Cameron Highlands road.

3.0        Scope of work

Kumpulan IKRAM Sdn Bhd  proposes the following scope of work that is deemed appropriate to meet the above stated objective.

3.1     To carry out site investigation works including drilling six numbers boreholes (deep boring works) for depth 90m.

3.2     To carry out geological study of soil and rock and provide a qualified Engineering Geologist through the duration of the boring works for the purpose of mapping or recorded the type of soils / rocks,  sub- soil profile, the rock fractures and the location of slip surface along  the discovered samples.

3.3     Kumpulan IKRAM Sdn Bhd  shall provide JKR with the Report
explaining engineering properties of the soils / rocks, sub – soil profile,  the rock  fractures, the location of probable slip surface.

3.4     To carry out instrumentation works including in-situ Field Permeability test in Rock using a Single Packer in N size diamond drill holes, standpipe piezometer, vibrating wire piezometer and preparation for TDR.

3.5     To carry out laboratory tests including shear strength tests, unconfined compressive test (UCS) , petrographic test and other strength test on rock where necessary.

3.6     To prepare and submit program for the works. The program shall include deliverable and delivery dates.

3.7     To provide JKR with all materials related to the works such as data, documents, drawings, photographs and reports both in digital and hard copies.  

4.0     Method of Statement

4.1     Justification for preliminaries and movement
         
The cost of study including drilling works as appendix 2. However we could not use the SOR as in agreement. The justification for certain items such as preliminaries and movement of rigs as follows:-

4.1.1  Preliminaries and General Conditions









a
Insurances



   42,000.00

WC
}
2 % 1,400,000.00



CAR
}





PL
}





SOCSO
}





Special insured on equipments
1.0%









b
Inspection of Site



     6,000.00







c
Temporary Access



   15,000.00







d
Personal/Workmen safety (10 person)

     3,500.00

Safety boots
2500




Helmets

500




Safety vests
500










e
Compliance to safety plan and Environment Impact Assessment (EIA)
     10,000.00







f
Watching and security at site@ 2 months

     10,000.00







g
Workmen’s Accommodation@ 2 months
   20,000.00








h
Transportation for water and fuel


     5,000.00







i
CIDB Levi



     3,500.00







j
Site clearance and rehabilitation of site after completion of works

     5,000.00







k
Storage for core samples/core boxes

10,000.00










Total


 130,000.00








4.1.2  Movement    


Breakdown of movement from BH to BH (7 days)






Personal / workers (10 person)

 10,500.00
Salary, OT and allowances


RM1,500/day








Rental of bulldozer / excavator

 17,500.00
RM 2,500/day








Fuel consumption for boring machine
   2,500.00







Total

 30,500.00





Profit and attendance (15%)

   4,575.00







Total

 35,075.00
Downtime (loss of time)                                                           


9,000.00







Total

 44,075.00



          4.1.3  Methodology of movement

A feasible study on the site condition was carried out during the site visit. Based on the study it was reckoned that there were two possibilities of accessing to the positions; either by tracking the most suitable access through a longer route that will take a longer time to reach or by using an excavator half way the mount and then dismantle the components of the boring machine to bring them manually to the test positions. Either way both methods will consume time and energy. Every shift has to be assessed separately on a case to case basis based on site and confidence of the team. The element of risk cannot be discarded. (See appendix 3 and 4  for details)

4.2     Safety and health plan

All safety measures and work procedures shall comply with OSHA requirements. IESSB shall not compromise on the safety aspects when carrying out the S.I works.

All forms of digging and cutting of soil shall be carried out in a manner to ensure minimum disturbance to the ground and environment 
         
4.2.1  Objective

To conduct operation in such a manner so as to avoid harm to employees and all others who may be affected by the Site Investigation activities.

(a)          To maintain the highest practically achievable standards of safety occupational health and environmental protection.

(b)         The company’s safety targets are :

-    Zero fatalities and minimal environmental damage.

-    To prevent any accident by pre planning and implementing the safety system.

-    To create safety awareness amongst all staff

-    To protect the environment on land from accidental contamination and damage.

          4.2.2  Risk Protection


4.2.2.1  Personal Health

a)    High standard of hygiene is expected at all work places.

b)   Cuts and abrasions should be cleansed at once and given
     first aid treatment.

c)    Proper first aid kit shall accompany the field crew at all
     times.

4.2.2.2   Personal Protective Equipment (PPE)


a)    Appropriate PPE shall be worn in consistent with the
     hazard :
(i)       long sleeve shirt
(ii)      gloves
(iii)    high-top boots
(iv)    helmets
(v)      reflective safety vest

4.2.2.3  Traffic Safety

a)    All personnel shall comply with traffic rules whether
on land or water.

b)   Drivers must be in possession of valid driving
     licenses.

c)    Night driving is to be avoided whenever possible.

d)   Only authorized personnel may drive company
vehicles.
                                               
4.2.2.4  Storm

Lightning usually strikes the highest point or object in any area because it is seeking the shortest path. The following precautions shall be taken when a storm is approaching:

a)    Inform the CSA / STE of the storm and suspend all
     operations
b)   Drop all metal tools, pipes and cables

c)    Take shelter. Stay away from trees; if possible take
     shelter inside a vehicle parked in a low open area rather
     than under trees.

4.2.2.5  Shifting of machinery in difficult terrain
         
a)    All personnel shall take necessary precaution to ensure
     the mast is lowered during shifting.

b)   Ensure minimum disturbance to soil and loose boulders
     when moving equipment and machinery.

c)    Always be alert for rolling boulders or possible landslides

d)   Use only the proper cable or rope to move the boring
     machine.

e)  When moving the machine up a steep grade, anchor all
     lines.

4.2.2.6  Emergency Procedures


In case of injury or illness the site Agent is to be contacted and informed of:
-        Nature of the accident / incident
-                      Seriousness of injury
-                      Whether medical assistance is required
-       Administer first aid if necessary
                             -        Investigate cause of accident / incident
-        Report to CSA / STE
-        Ensure a vehicle is on standby at the test location at
          all times.
  
4.3     Role of geologist

4.3.1  Objective:
         
The objective of work:
1)   To carry out Geological mapping of the project area
2)   To record the type of soil/rocks and sub soil profile
3)   To record the rock fractures and the location of slip surface along the discovered samples
4)   To carry out full time supervision by Geologist at site

          4.3.2  The method of work:

1)   Methodologies for the geological mapping with recording detail data; by choosing sections with a lot of rock outcrops. This geological mapping use appliance of topographic map of this area, geological compass, hammer, measuring tape, digital camera and GPS. Final report of the geological mapping is “Geological Map” of the project area. This map contains various type of rock and strata graphic of rocks from the bottom towards top.
 
2)   Methodologies for the recording detail data of rocks, sub soil and soil; with many detail sections from the bottom to the top. This detail sections use appliance geological compass, measuring tape, digital camera and GPS. The final report of this method will get rock formation from bottom to the top; it is including fresh rocks, weathering rocks and top soil.

3)   Methodologies for the recording detail data of rock fractures and slip surface; with detail measurements along the every area of rocks fractures and failure (slip surface) of the location of probable slip surface. This measurement use appliance, such as geological compass, tape and digital camera. Data recording are processing with the stereo and stereographic program to determine many type of slip surface and lineament or arrow of slip surface. 

4)   The C.V of the Geologist is as attached in appendix 9.
4.4     Field Exploration

          4.4.1  Procedure

                   All drilling works and test procedures shall be carried out in accordance with MS 2038:2006 , BS 5930:1999 and all laboratory testing shall comply with MS 1056

                   4.4.2  Deep Boring
         
4.4.2.1  Deep Boring Plant

The Boring Plant to be used is a ‘YWE D90R’ which is capable of boring and drilling to a depth of 100 metres using N size casings. It is a light machine and can be winched along the slopes using trees to hold. But , however, it is not suitable to drill to a depth of 90 metres using H size casings due to its limited capacity.

To drill into rock/ soil using  bigger size casings like the H or P sizes, a more powerful and bigger machine is more suited. But, however, bringing the bigger rig to the proposed site at the summit of the mount is not possible due to its size and weight. The terrain is too steep for such machines. It may pose a safety problem and endanger the lives of the workers and also the road users below.

4.4.2.2  Method of Advancing Boreholes – Wireline drilling and 
                             Sampling

Kumpulan IKRAM Sdn Bhd proposes that the wireline drilling and sampling method be used to advance the boreholes.

The main difference between wire-line drilling and conventional core drilling equipment is the drilling rods. Wire-line drill rods are thin hollow tubes known as ‘Q’ drill rods. The rods are hollow to allow the inner core barrel, over-shot assembly and wire-line to pass through them. Wire-line core drilling is basically the same as conventional drilling rods and core barrel. A diamond drilling rig with all other accessories is required.

Core barrel can be raised on a wire-line without removing the entire string of rods, as in the case of conventional core drilling. This is done by lowering the overshot assembly down the hole on the end of the wire-line. The overshot graps the inner barrel which can then be brought to the surface to remove the core. The inner barrel can then be lowered back down the hole where it fits into the outer core barrel and is in position to retain another core once the drilling is resumed. The drill rig must include a wire-line hoist in this operation .
Wire-line drilling is faster and cost effective for deep core drillings (please see appendix)


4.4.2.3  Size and Depth of Boreholes


The size of boreholes would be about 76mm. in diameter. It would be such that all the requirements of the sizes in sampling, in-situ testing, etc are satisfied.



4.5     Rock Drilling


          4.5.1  The procedure for rock drilling

The procedure for rock drilling shall be carried out in accordance with BS 5930 : 1999. The diameter of the core barrel used shall be such as to produce a rock core of about 50.0mm diameter that of  NQ core barrel. The Core Recovery Ratio (CRR) and the Rock Quality Designation (RQD) shall also be reported for each core run.

The CRR means the ratio of the total length of good quality core over the drilling length expressed to the nearest 5%. The RQD is the ratio of the total length of the good quality core each exceeding 100mm in length over the drilling run correct to circular circumference or in the case of broken rock fragments assembled to form cores with circular circumference.

          4.5.2  Preservation, Storage and Transportation of Rock Cores


Core samples shall be stored in the standard core boxes clearly labeled to show the drilling sequence. Any discontinuity in the core shall be clearly noted. The name of the project and borehole number printed on the cover.
          All rock cores shall be kept at IKRAM Central for a period of 6 months for the S.O. to inspect.

          Samples of cores randomly to be sent to approval laboratory and or JMG Ipoh/UKM (Jabatan Geologi) for identification type of rocks.

          4.5.3  Limitation of Rock Core size

As requested by JKR rock core size 75mm Ø for the whole depth of 90 meters could not be obtained due to the limited capacity of the boring machine.

5.0     Instrumentation and Monitoring Works

        5.0.1 Packer test (Permeability test in rock)


5.0.1.1 General Principles

The packer or Lugeon test gives a measure of the acceptance by in-situ rock of water under pressure. The test was originally introduced by Lugeon to provide a standard for measuring the impermeability of grouted ground; it is also widely used as a packer test to measure the permeability of dam foundations. In essence, it comprises the measurement of the volume of water that can escape from an uncased section of borehole in a given time under a given pressure. Flow is confined between known depths by means of packers, hence the more general name of the test. The flow is confined between two packers in the double packer test, or between one packer and the bottom of the borehole in the single packer test. The test is used to assess the amount of grout that rock accepts, to check the effectiveness of grouting, to obtain a measure of the amount of fracturing of rock, or to give an approximate value of the permeability of the rock mass local to the borehole.

The results of the test are usually expressed in terms of Lugeon units. A rock is said to have a permeability of 1 Lugeon if, under a head above groundwater level of 100 m, a 1 m length of borehole accepts 11/min of water. Lugeon did not specify the diameter of the borehole, which is usually assumed to be 76 mm, but the test is not very sensitive to change in borehole diameter unless the length of borehole under test is small.

A simple rule that is sometimes used to convert Lugeon units into permeability is to take one Lugeon unit as equal to a permeability of 10-7 m/s. An approximate value of permeability may also be calculated from the following formula, although the assumptions on which it is based are not always borne out in practice.

                                        Q                      L        
                                k  =  2p HL        loge          r  
 
                        where,

                        k       is the permeability in metres per second (m/s);

                                        Q      is the rate of injection in cubic metres per second (m3/s);          

                        H      is the pressure head of water in the test section in metres (m);

                        L       is the length of the test section in metres (m);

                        r       is the radius of the test section in metres (m).

Tests to assess permeability by means of packer tests are usually carried out at varying values of Q and H, and the value of k determined from the slope of the flow versus pressure graph.


5.0.1.2  (Pneumatic) Packers


This comprises a rubber canvas duct tube, which can be inflated against the sides of the borehole by means of pressurized gas. Bottled nitrogen or compressed air is fed down the borehole through a small diameter nylon tube. The inflation pressure should be that required to just inflate the packer to the required diameter, to seat the packer and to overcome the hydrostatic pressure in the borehole. Excessive pressures should be avoided. The difference between the diameter of the uninflated packer and the diameter of the borehole should be such that the packer can be easily inserted. At the same time, the inflated diameter of the packer should be sufficient to prove an efficient seal. A double packer is two packers connected by a length of pipe of the same length as the test section. The test water is introduced between the packers.

5.0.1.3  Application and measurement of pressure

It is essential that the maximum water pressure to be applied is not sufficient to cause uplift of the ground or to break the seal of the packers in deep holes in weak rock. The pressure to be determined for use in the calculation of permeability is that causing flow into the rock itself. The pressure can be measured directly with an electric pressure gauge set in the test zone or indirectly by gauges at ground level. The use of direct pressure measurement is preferred and pressures should be measured at the bottom and preferably below the test section. This avoids the difficulties associated with corrections for fluid density, friction losses etc. in indirect measurements. If it is necessary to take indirect readings at ground level, these are adjusted in accordance with the following expression:
                                       HT = P + (HHg) – Hf
                             Where
                             HT      is the pressure head causing flow into the rock in metres (m);
                             P        is the Bourdon gauge reading converted to head in metres (m);
                             H       is the height of Bourbon gauge above mid-point of test section in metres (m);
                             Hg      is the height of natural groundwater level above mid- point of test section in metres (m);
                             Hf           is the friction head loss in the pipes in metres (m).

5.0.1.4  Measurement of flow


The rate of flow of water may be measured either by a flow-meter or by direct measurement of flow out of a tank of known dimensions by means of a dipstick or depth gauge. Where a flow-meter is used, it should be installed upstream of the pressure gauge, well away from bends or fitting in the pipe-work, and in accordance with the manufacturer's instructions. The accuracy of the meter should be checked before the test begins, and periodically afterwards, by measuring the time taken to fill a container of known volume at different rates of flow. Where the flow out of a tank is to be measured, the use of one large tank can lead to inaccuracies where the plan area is large and the fall in level correspondingly small. A better arrangement is to use a number of small containers.

5.0.1.5  Execution of test


Developing or cleaning the borehole before testing is vital. The test may be carried out either as a single or as a double packer test. Appropriate measurement devices should be included to allow detection of leakage past the packers; this is assisted by continuous logging of the readings. However, the single packer test is normally done periodically during the drilling of the hole, which makes it more costly. An important point is to ensure that the packer is properly seated in the boreholes. Where a complete core has been recovered from the borehole, or where appropriate logging or television inspection has been carried out, a careful examination may reveal suitable places to seat the packer. Where the seating proves unsatisfactory, the length of the test section should be altered or test sections overlapped, so as to seat the packer at a different depth in the borehole.

Because of the limitation on the pressure referred to in 3.0, it may not be practicable to run the test at the (Lugeon) specified head of 100 m above groundwater level. The assumption is made that the water flow is proportional to the pressure, although this is not necessarily true. It is then possible to obtain the Lugeon value by extrapolation. For hydrogeological purposes, test pressures of less than about 5 m head are usually adequate. It is customary to run a series of tests at different pressures. Typically a series of five tests is desirable, with the maximum pressure applied in three or five equal increments and then reduced with decrements of the same amount. The full data record obtained from these measurements is particularly useful in assisting in the interpretation of the behaviour of the rock under test. ( see Appendix  5)


5.1     Ground water monitoring


          5.1.1  Standpipe Piezometer


Standpipe Piezometers shall be installed in selected boreholes as instructed by the Engineer. The final details of any piezometer installation shall be decided by the Engineer.

The piezometer tip shall consist of a porous ceramic element or other suitable element not less than 150 mm long with a diameter not less than 40mm, and shall be protected at each end by unplasticised polyvinylchloride ( upvc ) fittings. The ceramic shall have a pore diameter of the order of 60 microns and a permeability of the order of 3 x 10-4 m/s.

The tube shall be jointed together and to the porous element with approved couplings and glued is such a manner that the joint remain leak proof under the anticipated head.


5.1.1.1  Grouting


A grout of cement and bentonite in the proportions of 1:4 shall be used. If water in the exploratory hole is contaminated by grout it shall be replaced by clean water, the method being to the approval of the Engineer.

5.1.1.2  Sand Filter

The sand filter surround to the porous element shall be clean and fall wholly between the limits of grading 1200 and 210 microns and the volume of sand filter placed shall be recorded. The final elevation of the top of this sand shall be recorded. The porous element shall be placed in the hole and the remaining sand filter shall then be added as described above.

           
5.1.1.3  Surface Installation


The top of the UPVC tubing shall be covered by a plastic cap or similar as approved by the Engineer. An air vent shall be provided. Arrangement to protect the top of the UPVC tubing shall consist of a steel barrel of 75mm diameter which shall be set in concrete.

                     
5.1.1.4  Water Level


The ground water level shall be recorded immediately before and after installation of the piezometer. Before readings are commenced, the piezometer shall be filled with water and its correct functioning demonstrated to the Engineer. Each peizometer shall be clearly and permanently labeled giving the exploratory hole a reference number. During field works the ground water level in the standpipes piezometers shall be recorded. (see Appendix 6)


5.2     Vibrating Wire Piezometers

         
          5.2.1  General

The basic principle of operation is that a porous element is placed in the ground so that the soil water is continuous through the pores of the element, and this water is collected in a container unit. The pressure of the water in the container unit is recorded, and hence the water pressure in the ground is determined.

The Vibrating Wire (VW) piezometer comprises of a porous tip which contains a pressure –sensitive diaphragm, a tensioned steel wire and an electro-magnetic coil. One end of the wire is concreted to the diaphragm and the other to the body of the piezometer.

Pressure causes the diaphragm to deflect, reducing tension in the wire. The magnetic coil is used to ‘pluck’ the wire, causing it to vibrate.

The vibration of the wire near the coil generates a frequency signal that is transmitted via a signal cable to the readout unit.

          5.2.2  Equipment


a)            Drill rig capable of drilling a hole of 100mm ID ( HW casing ) to the required depth
b)           Vibrating Wire (VW) piezometers with High Air Entry or Low Air Entry ceramic filters, and signal cable.
c)            Installation tools and materials, geotextile bag, sieves 1.18mm and 600 um
d)           Vibrating Wire (VW) data recorder
e)            Protective device made of steel and lockable to cover the top of the borehole to minimize vandalism.
          5.2.3  Drilling of Hole

The size of the borehole is 100mm ID and is drilled with the use of water. Steel casing is used when necessary to prevent the collapse of the borehole.

The borehole is advanced to the specified depth as near vertical as possible, and the borehole flushed with water to clean the hole.

          5.2.4  Vibrating Wire (VW) piezometers Installation

The VW piezometer tip is immersed in cooled boiled water(de-aired water) for at least 24 hours to saturate the ceramic filter. It is then placed in a geotextile bag filled with clean sieved sand (passing 1.18 mm, retained on 600µm)

This operation is carried out with the piezometer underwater at all times. The whole assembly is left in de-aired water until just before placing in the borehole.

The use of the geotextile bag filled with sand is to prevent the clogging up of the ceramic filter of the piezometer during installation, and also it provides a minimum thickness of clean sand between the ceramic filter and the soil should the assembly for some reason cannot be placed in the centre of the borehole (this system in fact allows the piezometer to be placed more accurately in the centre of the borehole)

Ten to fifteen minutes after the piezometer has been lowered to the required depth, a reading is taken using the VW Data Recorder to check whether the piezometer is functioning or not.
Clean, sieved sand (passing 1.18mm and retained on 600µm BS test sieves) is poured into the borehole until a layer of sand is obtained at the bottom of the borehole (the thickness will be as directed by the Engineer)

The piezometer is lowered into the borehole and placed on that layer of sand. More sand is then poured in until the piezometer is covered by a layer of sand  of thickness as directed by the Engineer.

A bentonite plug is formed above this sand layer, and this sand layer by slowly dripping bentonite pellets of 0.5 inch diameter.

The thickness of this plug will be as directed by the Engineer. The rest of the borehole is the then grouted to ground level with a pumpable cement – bentonite mix (4.1)

The thickness of the various layers are measured using a measuring tape weighted down with a heavy weight, and lowered into the borehole periodically.

Each borehole will have only one piezometer and the piezometers will be marked at the end of the signal cable at ground level with tape bearing identification numbers written with permanent ink as directed by the Engineer. 

          5.2.5  Monitoring of the VW Piezometer 
 
Present day vibrating wire indicators incorporate automatic features which simplifies the taking of readings.
To read the pressure, the signal cable of the piezometer is attached to the indicator box, and the pressure or frequency read from the digital gauge.  (see Appendix 8)

5.3     Preparation of Time Domain Reflectrometry Holes ( TDR )

Time Domain Reflectrometry  holes shall be constructed , as instructed by the Engineer. The final details of any Time Domain Reflectrometry hole shall be decided by the Engineer.

The Time Domain Reflectrometry  hole shall consist of  a 50mm diameter unplasticised polyvinylchloride ( UPVC ) tube jointed together with approved couplings and fitted with an end cap. It is placed in a pre-bored hole through the whole length of the hole with about a metre of the UPVC sticking out of the ground at the surface. The UPVC shall be packed with cement bentonite grout in the proportion of 1:4.

A coaxial cable ( RG8) of approved quality with an outer diameter size of 10mm, as specified by the Engineer shall be affixed firmly to a 1kg weight at one end. The size of the weight shall be such that it can be placed at the bottom of the 50mm diameter UPVC tube with the cable positioned centered and as near vertical as possible.

The inner part of the UPVC tube with the coaxial cable shall be grouted with bentonite cement grout in a proportion of 1:9.  

5.4     The Monitoring of work starts after completion of field works on per trip basis irrespective number of different test.
6.0     Work programme

                  
The whole S.I works will take about 6 months to complete including instrumentation works. ( see appendix 1)


7.0     Financial costing


          The proposed S.I works is estimated to cost about RM 1.4 million.
         
Items that are not in SOR are subject to approval by JKR.
 ( see appendix 2 )











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