# Presentation: 846867

## NSLS – II  CFAC  Review

**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.
- 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

## 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.

## Geotechnical Conditions (cont’d)

## 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.

## 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’.

## 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