SOIL INVESTIGATION AND LABORATORY TESTING PLTU


SCOPE OF WORK
         
The scope of Soil investigation should be such as to clarify the soil conditions in order that satisfactory and economical foundations can be designed and proposed recommendations for suitable types of foundation and establishing the reliable soil parameter based on the analysis of the geotechnical data.

These investigations should be performed immediately after the Contract Award. The Contractor should submit the investigations program to the Owner for approval. The program approval does not relieve the Contractor from his obligation to undertake additional investigations of the soil based on the Owner’s request, and that may be the result of the soil investigation first report evaluation.


Investigation and elaboration of reports on investigation results and structures foundations conditions should be entrusted to an institution specialized for soil mechanics and foundation. Such an institution and the Report should be approved of by the Owner.

The work shall include but not limited to the mobilization and demobilization, transports and furnishing of all machines, equipment and installations necessary to perform the works specified hereafter, such as drilling rigs, rods, bits, casings, CPT, power generators, compressors, pumps, vehicles, cisterns and all other matters deemed necessary by the Contractor to perform the foreseen investigations as indicated in Book II, "Summary of Work" and Book IIIA refers to "Civil and Architectural Requirements".

CODES AND STANDARDS

The Contractor shall comply with the requirements of Book II, "Codes and Standards".

The Codes and standards of the following organizations extracted from Book II, "Codes and Standards" are specifically applicable to the design, manufacture and testing of the work included in this specification.

ASTM : American Society for Testing and Materials

BS : British Standard
         
AASHTO : American Association of State Highway and Transportation Officials.                                                  


WORKS EXECUTION

SCOPE OF INVESTIGATION

The following minimum of the investigations program is compulsory:

a.    22 bore holes on new site with total depth of 880 m

b.   15 static cone penetrations test on shore to the depth of 30 m in average.
c.    In each of the bore holes, undisturbed samples of soil shall be taken in 5.00 m interval and minimum 1 (one) at each different layer, vane test and SPT test shall be performed in 1.00 m interval.
d.   Testing laboratory for undisturbed and disturbed samples of soil properties.


CORE DRILLING

PROCEDURE

          Core drilling will be carried out by rotational method with clear water flush or on the request of the Owner without any flush at all.

Core recovery is required on the entire length of all drillings. A minimum core recovery of 90% is requested. Only material not altered or damaged by the drilling process will be considered as “core“. Zones where SPT, vane tests or undisturbed sampling performed are considered as zones with recovered core.

Cores have to be handled carefully in order to prevent deformation or breaking.

DEPTH

Drilling equipment must be able to perform bore holes to a depth of 50 m.

The final depth of the bore hole, as well as the depth achieved with every core run will be measured with the drill rods in accuracy of 5 cm.

If a boring does not reach the required depth, an additional hole has to be drilled and no compensation will be given for the abandoned hole.

The Owner is entitled to change the length of borings based on geological features.

DIAMETERS

The initial diameter shall have to be chosen by the Contractor. The final core diameter should not be less than 54 mm.

In order to allow proper telescoping, core barrels, bits and casing for several diameters should be on the site.

OTHER OBLIGATIONS TO THE CONTRACTOR

          The Contractor shall assist the Owner during core logging and for all other works related to the preparation and supervision of the Contractor's work.

The Contractor shall take colored picture of all cores. Two copies 9 x 13 cm and the negative shall be handed over to the Owner.        

Each finished bore hole shall be marked by a concrete block cast in place, with a minimum base dimension of 40 x 40 cm and a minimum height above ground surface of 10 cm. The number of the bore holes has to be engraved in the concrete.

EQUIPMENT

Rigs shall meet the following specifications :

-     Hydraulic or mechanical feed : Transmission gear to adjust spindle speed (e.g. 60 to 300 rpm).

The core barrels shall be in perfect, which guarantee the request core recovery. The use of single   tube core barrels is not allowed.

Diamond bits and hardened steel bits in perfect condition from a well known manufacture shall be used.

The Contractor shall supply all necessary flush water for the execution of boring and pertinent tests. Facilities for sedimentation and water reservoir of adequate capacity may be necessary. Only clear water shall be used.

The Contractor shall establish the sequence of drilling and testing based on the frequent requirements for the different bore hole tests to guarantee testing and sampling in natural soil conditions and to allow for a reasonable drilling progress. The sequence shall be approved by the Owner.

Core boxes should be made of good and durable material and covered by a lid with hinges.

The inner length of a core box shall be 1 m and for each meter of bore hole one meter of core box shall be foreseen. The end of each core, as well as other pertinent information (e.g. core loss, extracted sample, etc) has to be made immediately in the core boxes with indication of actual depth.

Inscriptions on the boxes have to be punched into aluminum or plastic straps.

The boxes must show the following indications on the inside of the lid :

-              Job site
-              Number of bore hole
-              Date of finishing the bore hole
-              Number of the box
-              Depth interval

The boxes must show the following indications on the outer small side :

-              Job site
-              Number of bore holes
-              Number of the boxes

Core boxes have to be stored in such a way that they are protected against rain and sun.


STANDARD PENETRATION TEST  (SPT)

The test shall be made according to the following standards :

ASTM Designation D 1586 or BS 1377, Test 19.

The extracted sample shall be packed and sealed in a plastic bag and placed in the core box. It shall be labeled for identification with date, bore hole number, depth and number of blows.

With the sampler resting on the bottom of the hole, drive the sampler with blows from the 140 pound hammer falling 75 cm until either 45 cm have been penetrated or refusal (defined as 100 blows per 15 cm or less of penetration) has been reached.

Standard reporting shall give the number of blows for the first, second and third penetration of 15 cm. If the number of blows for the first 15 cm would exceed 20, the penetration depth for the first, second and third 20 blows shall be reported. Further more it shall be reported if the hammer is free chopping or fixed by a rope


VANE TEST

The test shall be done according to the standard ASTM D 2573, AASHTO T223, BS 1377,T18 or another standard approved by the Owner.

To allow for calibration it shall be performed just below the location of a SPT test.

The test shall be performed in such a way that the rods are isolated from the soil, i.e. that no friction occurs between the rods and the soil.

The maximum and residual value of torque and corresponding shear strength shall be reported.


PERMEABILITY TEST

If there were any sandy layers of the subsoil, the permeability shall be measured with the falling head test method.

The test shall be performed where such a layer is encountered or as directed by the Owner.

In general, not more than 2 tests shall be performed in one sand layer and no test shall be closer than 3 m to the next one.

Before perform the test, the bottom of the bore hole shall be cleaned and the water within the casing shall be clear. The ground water level at the time of the test shall be registered.

For the test, the casing shall be filled with clear water and the falling of the head in function of time shall be measured. Registration time may be up to 20 minutes.

After the test, the depth of the bore holes has to be controlled.

If the casing is telescoped, special measures are needed to avoid water loss at the level of diameter change.

The record of tests shall include:
-       depth of boring
-       depth of ground water level
-        duration of test
-        diameter of casing at depth of casing and water level measurements
-        array of data with time and fall of water level during test.

The Contractor shall interpret the data and give the permeability of the measured soil layer.

Data and interpretation shall be handed over to the Owner on approved forms within 48 hours.

The compensation for test is independent of the diameter of the depth below surface where the tests were performed.

The supply of the required water volume for flushing the hole and testing is understood to be part of the test and the Contractor is not entitled to any additional payment irrespective of the volume of water lost in preparation and performance of the test.


SAMPLING

In the course of the field investigations, 3 types of samples shall distinguish:


All samples are taken from the drillings. Within counting the SPT  samples, one sample shall be taken every in 1 m interval.

Undisturbed soil samples are extracted from bore holes with a special instrument, as defined in ASTM D 1587, in fine grained or cohesive soils.

The instrument is subject to the Owner's approval.

Undisturbed soil samples shall be taken in appropriate soils every 5 m interval or at regular intervals, as directed by the Owner.

Disturbed samples shall be of soil, taken from cores and packed and sealed in plastic bags or plastic tubes. Number, type and size of these samples are directed by the Owner.

All samples shall be labeled. The label shall indicate the project, site, bore hole, depth and date of extraction.

On the site, the samples shall be stored in a special place sheltered from sun and rain.


CONE PENETRATION TEST (CPT)                  

CPT equipment and testing procedure shall be in accordance with the recommended standard, established by the subcommittee on Standardization of Penetration Testing in Europe published i.e. in the Conference Papers of ICSMFE. Tokyo 1977, vol.3, pg.95 ff.

Deviations from that standard shall be indicated in the test report and need to be approved by the Owner.

Based on the actual geological knowledge depth are envisaged for testing: 30 m.

The test results shall be presented in a plot of cone resistance and total side friction versus depth.

Additionally, but not alternatively the Contractor may offer the measurement of the pore water pressure versus depth. In this case the Contractor shall submit a description of this equipment and indicate the price for such readings per linear meter as an over item to the price of CPT.

The test records shall be handed over to the Owner within 48 hours after test performance.

They shall also be integrated in the Final Report.

Such payment includes also the set up of the test equipment at each location.


LABORATORY TESTING

The samples taken in the field shall be transported to the laboratory at least every fortnight.

The Contractor is then responsible for adequate storage, extraction, description and preparation of each sample. All this work shall be included in the unit prices of tests and no extra compensation is given for such work.

The Contractor will receive, from the Owner, a test list indicating the tests to be performed for each sample. If, for any reason, this test program can not be followed, the Contractor shall immediately inform the Owner and furnish reasons.

The number of each test given is the minimum requirement.

Variations from the given quantities may be directed by the Owner.

For each test, the Contractor shall indicate the standard he will follow.

Deviations from any standard or the use of other standards than the ones specified hereafter need the written approval of the Owner.

The following tests for soil properties shall be performed in accordance with ASTM and/or AASHTO and/or BS standards. Test and data recording shall include:

-       Particle size analysis of soil, ASTM D422 or AASHTO T88 or BS1377.

-       Liquid limit of soil, ASTM D423 or AASHTO T89 or BS 1377.

-       Natural water content, ASTM D2216 or BS 1377.

-       Natural (moist) unit weight, BS 1377.

-       Specific gravity, ASTM D854 or AASHTO T100 or BS 1377.

-       Organic matter, ASTM C40 or ASTM T21 or BS 1377.

-       Permeability, ASTM D2434

-       Unconfined compression strength, ASTM D2166 or AASHTO T208 or BS 1377.

-       Consolidation, ASTM D2435 or AASHTO T216 or BS 1377

-       Triaxial shear strength, AASHTO T266 or BS 1377

-       Direct shear strength, AASHTO T236


REPORTS

DAILY REPORTS ON FIELD WORK

The driller will daily carry out a report, containing:

-       Diameter and type of bit
-       Diameter and depth of casing
-       Rotation velocity
-       Drilling pressure
-       Total water losses
-       Pressure of clear water flush, color of flush
-       Depth and time interval of core runs
-       Types of soil
-       Water level in hole at beginning and at end of shift, intermediate measurements
-       Any other pertinent information

The form of the daily report is subject to the Owner's approval.

There is no extra compensation for the daily reports.

FINAL REPORT ON FIELD WORK

The Final Report will obtain the following items:

Activity time schedule of investigation program (table)

Layout of the area where PLTU Kalimantan Selatan (2 x 65 MW) is to be constructed, with structures locations indicated, and the positions of investigations shall be carried out.

Drilling equipment used by the Contractor on site (list)

Comments on the performed work.

Drawings of the bore logs.

Complete data and interpretation for all field tests as SPT and permeability.

List of all extracted samples (SPT, disturbed and undisturbed ) Logs of CPT.

 DRAFT REPORT.

A draft of the Final Report is subject to the Owner's approval. It shall be. delivered not later than 1 week after termination of the field work.

PROGRESS REPORT OF LABORATORY WORK.

Every two weeks, the Contractor shall prepare and forward to the Owner one report with the following features :

-       Samples received
-       Tests performed
-       Deviation from the test program
-       Comments on the test program and on the test result
-       An annex containing all test results of the given period

No extra compensation is foreseen for the Progress Reports.

TEST RECORD

          All forms for the test readings and interpretations shall be approved in advance by the Owner. The Owner may also require additional forms or different plots.

FINAL REPORT ON LABORATORY WORK

The final report shall contain the following items:

-       a sample list
-       a list of performed tests
-       Summaries of test results, arranged according to technical,  geological or geotechnical features
-       all test results, readings, plots and interpretations.

The Contractor shall first prepare a draft issue of the Final Report and submit it to the Owner for approval. It shall be delivered not later than 4 weeks after termination of the field works.

All forms and reports shall be in English.

The Contractor shall hand over 5 copies of the Final Reports to the Owner. Furthermore shall provide to the Owner, the original of all text and data sheets and a transparent copy of all drawings.

The lump sums for reporting shall include all data collections, typing, copying, interpretation, calculation, designing, drawings, reproducing, posting, as well as all paper and other material and work necessary, to provide the required and approved reports.

The contract work is regarded to be terminated after the Owner has accepted in writing, the draft of the Final Reports and after the Contractor has delivered all originals and copies of the Final Reports in correspondence with the accepted Draft Reports, as specified above.





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