| Elevation of Bottom of Structure | Elevation of Bottom of Deepest Excavation | Lateral Earth Support System | Type of Foundation |
||
|---|---|---|---|---|---|
| Subway | Amtrak | ||||
| Gainsborough Street | 6.0 | 3.3 | 3.6 | None, excavation sloped | Belled caissons bearing on clay crust |
| Massachusetts Avenue | 6.0 | -6.0 | -7.5 | Steel sheet piling | Rectangular pedestals bearing on clay crust |
| Blackwood Street | -8.2 | -14.4 | -23.0* | Concrete diaphragm wall | Slab on compacted gravel borrow replacement fill |
| West Newton Street | -10.4 | -16.7 | -24.5* | Concrete diaphragm wall | Slab on compacted gravel borrow replacement fill |
| Harcourt Street | -10.4 | -16.4 | -24.5* | Concrete diaphragm wall | Slab on compacted gravel borrow replacement fill |
| Yarmouth Street | -4.7 | -12.4 | -14.4 -18.4** | Steel sheet piling | Precast-prestressed concrete piles to glacial till/bedrock |
| Dartmouth Street | 3.6 | -4.0 | -5.6 -12.4** | Soldier piles & lagging to south (Amtrak) side. None to north side. | Precast-prestressed concrete piles to glacial till/bedrock |
| Clarendon Street | 3.6 | -5.0 | -6.4 -9.6** | Soldier piles & lagging to south side. None to north side. | Precast-prestressed concrete piles to glacial till/bedrock |
| Berkeley Street | 1.6 | -5.0 | -6.4 -8.4** | Soldier piles & lagging to south side. None to north side. | Precast-prestressed concrete piles to glacial till/bedrock |
| Chandler Street (to east end) | -2.1 | -3.0 | -4.4 | Soldier piles & lagging to south side. None to north side. | Precast-prestressed concrete piles to glacial till/bedrock |
Notes: Information was obtained from 1981 and 1982 Massachusetts Bay Transportation Authority construction plans for Contracts No. 097-115 and 097-120.
*Removed organic silt to top of clay stratum.
**Lower elevation for trench excavated for track drain pipe.