7NT Engineering

Overview Capabilities Process Projects Contact

Capability overview

Drilling

Every civil construction project starts with geotechnical investigation, and complex tunnel projects require especially precise sampling and data collection. 7NT owns drill rigs equipped for soil sampling, rock coring, packer testing, and deep instrumentation work.

7NT provides highly specialized drilling services for civil and tunnel projects where accurate geotechnical data is critical to design, constructability, and risk reduction.

The original 7NT service page emphasizes that tunnels are especially sensitive to subsurface uncertainty because inaccurate information can create costly claims, field delays, and equipment problems.

The team regularly supports major firms on complex drilling and instrumentation programs, including soil sampling, rock coring, packer testing, and piezometer installation.

What this includes

Capabilities

Soil sampling and rock coring for deep tunnel and CSO projects
Vertical and inclined borings into bedrock
Hydraulic conductivity and wireline packer testing
Standpipe and vibrating wire piezometer installation
Deep drilling programs in varied geologic conditions
Specialized rigs, support trucks, tools, and barge-supported drilling

Critical drilling data

Consistency of soil and rock strata for tunnel alignments
Fracture orientation, spacing, and infilling
Voids, seams, and other inconsistencies
Timing of core runs to help evaluate TBM production
Quality samples for abrasivity, moduli, drillability, and hardness testing
Hydraulic Conductivity / Packer Testing
Standpipe piezometers and vibrating wire piezometers

Specialized tunnel experience

More than 500 deep borings completed since 2008, many over 200 feet deep
Deep drilling experience in Indianapolis, Fort Wayne, Louisville, St. Louis, Cleveland, Cincinnati, and Hartford
Specialized equipment and trained personnel for complex CSO, tunnel, and deep subsurface programs
Tunnel investigation support focused on reducing risk, cost exposure, and contractor uncertainty
7NT describes retaining its drilling team as a low-cost or no-cost way to help insure against inaccurate drilling data

No-cost insurance examples

The Deep Rock Tunnel Connector records were described as comprehensive and were included as part of the contract documents
The Deep Rock Tunnel Connector bid came in approximately 80 million dollars under the engineer's estimate
The South Hartford tunnel bids were described as 30 million to 50 million dollars under the engineer's estimate

Drilling equipment - rigs

(2) CME 550 X ATV rigs with angle capacity
CME 750 ATV with angle capacity
CME 75 truck mount with angle capacity
CME 45 skid mount
55 CME track mount

Support trucks and field support

(2) GMC C-7500 water trucks
(16) one-ton support trucks
(10) various smaller support trucks
Eight deck-over trailers
Four Troll systems

Drilling tools

100 feet of 2.25-inch HSA and 300 feet of 3.25-inch HSA
400 feet of 3.25-inch HSA
600 feet of 4.25-inch HSA
150 feet of 6.25-inch HSA
200 feet of 3-inch NW casing
250 feet of 6-inch casing
1,100 feet of 4-inch HW casing
Six or more casing advancers
Two 10-foot NW core barrels
Four 10-foot NQ3 wireline core barrels
Nine 10-foot HQ3 wireline core barrels
Two 5-foot PQ wireline core barrels
Eight HQ3 double packer systems with transducers
Three NQ3 double packer systems with transducers

Barge-supported drilling

36' x 20' spud barge
Support boat

Drilling capabilities

Soil sampling
Rock coring
Deep borings
Inclined borings
Wireline coring
Mud rotary drilling
Air rotary drilling
Packer testing
Instrumentation installation
Standpipe piezometers
Vibrating wire piezometers
Pavement coring
Concrete coring
Environmental drilling
Monitoring well installation
Difficult-access drilling
Barge drilling
Support for geotechnical investigations

How 7NT works

Service process

Define the drilling purpose, target data, and design or construction risk being reduced.
Select the rig, access plan, tooling, sampling method, and instrumentation needs for the site.
Capture high-quality field data, samples, cores, and measurements that can support engineering decisions.
Coordinate lab testing, documentation, and project records so owners and designers can rely on the results.