1. purpose
1.1 This fabrication and erection specification defines for the contractor the minimum requirements for the subsurface investigation to be performed and the corresponding geotechnical report to be submitted to Air Products.
2. scope
2.1 This specification applies to all subsurface investigations.
2.2 The contractor who shall be a licensed geotechnical consultant shall furnish all equipment, materials, and labor necessary to explore and evaluate the surface and subsurface soil conditions within the area of the proposed construction and shall provide recommendations for use in foundation design. All work shall be performed under the direct supervision of an experienced and competent soils engineer or engineering geologist who shall be named in the contractor’s proposal.
3. RELATED DOCUMENTS
3.1 American Society for Testing and Materials (ASTM)
D 5434 Standard Guide for Field Logging of Subsurface Explorations of Soil and Rock
G 57 Standard Test Method for Field Measurement of Soil Resistivity Using the Wenner Four-Electrode Method
4. investigative procedures
4.1 Field Investigation
4.1.1 The geotechnical consultant shall perform sufficient core borings, excavations of test pits, sampling, testing, and other investigative operations to adequately determine the existing subsurface conditions within the specified area of the project. The Geotechnical Consultant’s proposal shall indicate a proposed field sampling and testing program including the types and the frequency of samples and tests, and a proposed laboratory testing program including the types and the number of tests.
4.1.2 Prior to commencing the field work, the geotechnical consultant shall locate all public and private underground utilities and shall request Air Products to locate all plant underground utilities. All work shall be performed at a sufficient distance from both underground and aboveground utilities to protect the public, the personnel, and the utilities.
4.1.3 Test borings shall be drilled at the locations shown on the contract drawings. Depth of the borings shall be verified by the soils engineer, but shall be to a depth of at least twice the anticipated foundation width for the structure or equipment to be supported or shall be to a depth sufficient to provide data necessary for the determination of foundation design recommendations and expected short- and long-term settlements.
4.1.4 Soil sampling, standard penetration resistance, cone penetration resistance, and other field tests shall be performed in accordance with the applicable ASTM methods and procedures. Standard penetration testing and split-barrel sampling of soils shall be performed at intervals of 5 feet where practical. When cohesive soils are encountered, undisturbed samples shall be obtained from each significant stratum. Field logs of borings shall be kept in accordance with ASTM D 5434 and shall show soil descriptions, consistency evaluations, boring depths, penetration blow counts, location of undisturbed samples, and groundwater conditions.
4.1.5 If there is any indication of soil or groundwater contamination, the soils engineer shall immediately suspend all work and inform Air Products. Work shall not be resumed until notification to proceed is received from Air Products.
4.1.6 All completed boreholes shall be completely grouted with a mixture or Portland cement and bentonite. Weight of the bentonite in the mixture shall be between 4% and 15%.
4.1.7 When specified on the contract drawings, soil resistivity shall be measured at grade in the field using the Wenner four-electrode method in conjunction with a Megger or Vibroground instrument in accordance with ASTM G 57. Single probe-type instruments shall not be used. Tests shall be performed at a minimum of four site locations. Electrode spacings shall cover the range of depths at which the piping will be installed. The correct unit for resistivity is ohm-centimeter.
4.2 Laboratory Investigation
4.2.1 Laboratory investigation work shall consist of the visual classification and the establishment of moisture content of the samples obtained during the soil test boring operations. Soils shall be classified using the Unified Soil Classification System (USCS). Consolidation tests, compaction tests, gradation tests, Atterburg Limit tests, permeability tests, soil resistivity tests, and California Bearing Ratio (CBR) tests shall be performed as required and in accordance with the applicable ASTM methods and procedures. These tests in conjunction with standard penetration resistance shall be used to determine the foundation design recommendations and to estimate the engineering characteristics of the subsurface materials.
4.2.2 Soil resistivity shall also be measured in the laboratory using soil samples. Tests shall utilize a soil box that incorporates the four-pin method. The soil samples shall also be analyzed for pH, chlorides, sulfides, and conductivity.
5. report
5.1 The contractor shall prepare a report detailing the investigation and the findings. The final report shall be submitted under the seal and signature of a geotechnical engineer who is legally entitled to practice engineering in the state in which the project is located. The report shall contain all of the following information:
5.1.1 Description of work performed
5.1.2 General description of the subsoil conditions including any unusual or unanticipated conditions encountered
5.1.3 Plan drawing showing the location of the core borings
5.1.4 Log of test borings including:
Boring number and location
Groundwater level
Laboratory classification of samples
Standard penetration blow counts
Surface elevation at boring
5.1.5 Results of all field and laboratory tests
5.1.6 Recommendations for site preparation and development including:
Availability of and specifications for backfill and structural fill
Compaction equipment and procedures for utilization of in situ material and various classes of backfill, structural fill, and other specified material
Presence of expansive soils
Required depth of stripping
Suitability of on-site material for use as backfill and structural fill
Sulfate content of groundwater expressed in parts per million (ppm)
Treatment for improving subgrade, if required
5.1.7 Recommendation for the most suitable type of foundation
5.1.7.1 For shallow foundations (soil bearing):
Bottom of foundation elevations and allowable net bearing pressures with associated factors of safety for different size footings and mats
Calculated maximum and differential settlement values of various size foundations
Coefficient of sliding friction between the soil and the bottoms of the foundations
Dynamic modulus of elasticity
Dynamic shear modulus
Groundwater elevation for design purposes
Increase in allowable net bearing pressures under temporary loading
Modulus of subgrade reaction for mat foundation design
Time rate of settlement
5.1.7.2 For deep foundations (piled or drilled piers):
Allowable lateral load capacity. Applied lateral loading versus deflection of pile head. Pile moment versus depth
Allowable load per pile (both tension and compression) and factors of safety for different load combinations
Expected drag down (negative skin friction), if any
Expected settlement under gravity loads
Installation considerations such as equipment requirements, driving criteria, pre-drilling requirements, and casing/slurry considerations
Lateral subgrade modulus for each soil strata, allowable end bearing, and allowable skin friction for drilled pier design
Load test requirements, procedures, and acceptance criteria
Pile spacing, group action, and use of batter piles
Type, cross-sectional properties, and length of piling or drilled piers
5.1.8 Recommendations for earth-retaining structures including active, passive, and at rest lateral soil pressure coefficients
5.1.9 Discussion of groundwater conditions including potential dewatering requirements and appropriate methods of dewatering deep excavations
5.1.10 Recommendations for roadway and pavement design utilizing applicable U.S. Department of Transportation (DOT) specifications for the type of vehicle loading that is specified on the contract drawings.