The Challenge

  • South Hartford Conveyance Tunnel: One of North America’s largest wastewater projects.
  • Reducing or eliminating combined sewer overflows (CSOs) during storm events

The South Hartford Conveyance Tunnel is one of North America’s largest wastewater storage and conveyance projects. The South Hartford tunnel includes construction of an 18-ft finished (lined) diameter tunnel, 21,800-ft in length in deep rock. During storm events, the system is overwhelmed, spills occur and sewage is released to the environment. The South Hartford Conveyance Tunnel is being designed to reduce or eliminate combined sewer overflows (CSOs) to local water bodies.

The Solution

GTX provided expert soil and rock testing for the design phase of the tunnel. Careful handling was required in the preparation of test specimens to prevent breakage of fragile bedded rock. GTX transported Shelby tube samples from the client’s core shed directly to our lab to minimize soil disturbance.

Soil tests performed:

  • ASTM D2216 Moisture Content
  • ASTM D2435 Incremental Consolidation
  • ASTM D2850 UU Triaxial
  • ASTM D422 Grain Size Analysis
  • ASTM D4318 Atterberg Limits
  • ASTM D4452 X-Ray of Shelby Tubes – Digital Imaging
  • ASTM D854 Specific Gravity
  • ASTM D4648 Laboratory Vane Shear
  • ASTM D4767 CU Triaxial Shear with Pore Pressure Measurements
  • ASTM D7181 CD Triaxial

Rock tests performed:

  • ASTM D3967 – Splitting Tensile Test (Brazilian)
  • ASTM D4644 – Slake Durability
  • ASTM D5607 – Sliding Friction of Rock by Direct Shear
  • ASTM D7012C- Uniaxial Compressive Strength of Rock
  • ASTM D7012D- Elastic Moduli of Rock in Uniaxial Compression
  • ASTM D7625 -CERCHAR Abrasivity Index (CAI)
  • ISRM – Unit weight, porosity and specific gravity of rock
  • NTNU 13A-98 – Drillability test suite
  • Abrasion Value (AV)

Services Provided

Soil & Rock Testing

Complete capabilities of desired soil and rock tests performed in one laboratory

Quick Turnaround

Quick turnaround on testing as each phase of the field boring program was completed

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Data generated allowed for successful determination of
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Provided safe transportation of fragile 90 year old rock
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Quick turnaround on hundreds of samples tested
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