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1 BROOKHAVEN SCIENCE ASSOCIATES NSLS – II CFAC Review Conventional Facilities Geotechnical Conditions Tom Joos Civil/Structural Engineer BNL Plant Engineering Division October 18, 2006

NSLS – II CFAC Review

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NSLS – II CFAC Review. Conventional Facilities Geotechnical Conditions Tom Joos Civil/Structural Engineer BNL Plant Engineering Division October 18, 2006. Geotechnical Conditions. Subsurface exploration program conducted July & August 2006. - PowerPoint PPT Presentation

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Page 1: NSLS  –  II  CFAC  Review

1 BROOKHAVEN SCIENCE ASSOCIATES

NSLS – II CFAC Review

Conventional FacilitiesGeotechnical Conditions

Tom JoosCivil/Structural Engineer

BNL Plant Engineering DivisionOctober 18, 2006

Page 2: NSLS  –  II  CFAC  Review

2 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions

• Subsurface exploration program conducted July & August 2006.• Survey of proposed site conducted June 2006. • Additional soil boring data from adjacent project sites:• Center for Functional Nanomaterials (CFN) - 2003• National Synchrotron Light Source (NSLS) - 1977

Page 3: NSLS  –  II  CFAC  Review

3 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions (cont’d)

• 2006 Subsurface Exploration Program • Test borings taken at four locations

• Standard Penetration Tests continuous for first 10’ of depth.• SPT at 5’ depth intervals thereafter.• Borings to depths between 32 and 62 feet.• Soil samples collected from SPT tests.• Particle size (sieve) analysis performed on soil samples.

• Cone Penetrometer Soundings taken at 12 locations• Shear wave velocity measurements at 4 CPT locations.• CPT to depths between 53 and 100 feet.

Page 4: NSLS  –  II  CFAC  Review

4 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions (cont’d)

Page 5: NSLS  –  II  CFAC  Review

5 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions (cont’d)

• Subsurface Exploration Results• Site consists of 3 to 6 feet of fill overlying a naturally deposited

(glacial) sand exceeding 100 foot depth.• Groundwater encountered from 38 to 37 feet below existing

ground surface.• SPT N-Values

• Fill layer – 8 to 15 blows per foot (bpf) - loose to medium dense.• Sand Layer – 15 to >50 bpf - medium dense to very dense• N-Values calculated from CPT results averaged above 20 bpf.

• Shear wave velocity measurements ranges 860 to 1,180 fps.• Velocity was uniform to slightly increasing with depth.• Average of 34 measurements is 975 fps.

Page 6: NSLS  –  II  CFAC  Review

6 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions (cont’d) • Recommendations for design:

• Foundations• Maximum allowable bearing pressure 2.5 tons per square foot (tsf).• Minimum footing width of 3 feet.• Estimated total settlement for column footings of 1 inch/differential settlements <0.75 inch.

• Will be much less for slabs on grade• Expect 90% of settlement before end of construction.• These are typical values for this type of soil on BNL Site – not problematic

• Floors• Slabs on grade placed on minimum 6” thick layer of compacted structural fill.• All structures are above groundwater levels encountered.

• Foundation soils are Site Class D, “very dense soil/soft rock” (BCNYS/IBC 2000). • Existing fill layer to be removed below foundations.

• Proposed floor elevation 73.• Existing site grade varies from Elevations 83’ to 70’.

Page 7: NSLS  –  II  CFAC  Review

7 BROOKHAVEN SCIENCE ASSOCIATES

Geotechnical Conditions (cont’d)

• Conclusions/path forward• Proposed site appears to be excellent for NSLS-2 siting.

– Soil conditions fairly uniform throughout proposed site.– No evidence of clay or poorly consolidated (soft) sands beyond topmost fill

layer.– Recommended bearing capacity is favorable to proposed foundation design

(individual spread footings).• Further investigation (Title I/Title II)

– Additional borings to further quantify thickness of fill layer ($$$).– Test Pits

- Further define obstructions in warehouse area- Obtain samples for laboratory density tests

• Geotechnical risks are mitigated by having site preparation performed well in advance of general construction