Complex Drilling Services
Accurate Geotechnical Data
The major goal of the geotechnical drilling and testing is to gain as much ACCURATE data of the soil, rock and water as possible. The more accurate the data, the less risk the Owner will bear during construction.
A primary risk factor in tunnel construction is inaccurate geotechnical data. This data is gathered during the planning stages of the project and later refined during the design stage.
Decisions regarding the expenditure of hundreds of millions of dollars are made based on the data gathered by the drilling firm. While the Owner will often spend significant resources in evaluating and selecting the Prime Design Firm, the drilling firm is usually hired for local, political and low cost reasons. This is ill-advised. Most drilling firms do not have the specialized experience needed to perform this work accurately.
SELECTION OF THE DRILLING FIRM SHOULD GET THE SAME LEVEL OF ATTENTION AS SELECTION OF THE PRIME DESIGN FIRM.
Information is gathered by drilling borings; deep, vertical and inclined, into the bedrock to gather soil and rock samples that are utilized in laboratory testing while also creating an opportunity to perform down-hole in-situ testing to aid in obtaining the following critical data:
Highly Specialized Experience
7NT has highly specialized experience in conducting deep borings related to CSO projects. We have developed proprietary systems and procedures to accurately gather the data specified above. Key elements of our experience are as follows:
- Over 500 deep borings since 2008 in diverse locations & geological conditions around the country.
- Successful investigations on major tunneling projects in Indianapolis, Ft. Wayne, Louisville, St. Louis, Cleveland, Cincinnati and Hartford.
- Specialized equipment and trained personnel specifically geared towards deep CSO projects.
- Deep tunnel CSO projects are high risk projects as 9-figure decisions are often made based on limited geotechnical investigation. Even small inaccuracies in this data have resulted in change orders in the tens of millions of dollars.
- Retaining 7NT to perform the drilling is a low/no cost way of insuring against this risk.
DRTC project in Indianapolis set world records for mining in a day, a week and a month.
DRTC project in Indianapolis is $80 million under budget, while the remaining 18 miles of the Indianapolis system are currently projected to come in $70 million under engineer’s estimate.
South Hartford Conveyance Tunnel had multiple bids come in $30 million to $50 million under engineer’s estimate.
“Thanks for your dedication. Please extend my Thanks to the Crew. This is what makes my job easy, keep up the Great Job!”
No Cost Insurance
Deep tunnel CSO projects are high risk projects as 9-figure decisions are often made based on limited geotechnical investigation. Even small inaccuracies in this data have resulted in change orders in the tens of millions of dollars.
Retaining 7NT to perform the drilling is a low/no cost way of insuring against this risk.
For little or no additional cost, the owner can hire the best drilling firm and reduce the substantial risk associated with inaccurate data gathering.
7NT’s track record on CSO tunneling projects includes the following:
- DRTC project in Indianapolis set world records for mining in a day, a week and a month.
- DRTC project in Indianapolis is $80 million under budget, while the remaining 18 miles of the Indianapolis system are currently projected to come in $70 million under engineer’s estimate.
- South Hartford Conveyance Tunnel had multiple bids come in $30 million to $50 million under engineer’s estimate.
Drilling Equipment
Equipment is another area that distinguishes 7NT from other drilling firms. The equipment is the means by which the experienced and knowledgeable personnel carry out their responsibilities effectively and efficiently. 7NT has made significant investments in its equipment for our personnel to be the most effective. A condensed listing of the 7NT owned equipment includes the following:
- (2) CME 550 X ATV w/ angle capacity
- CME 750 ATV w/ angle capacity
- CME 75 Truck Mount w/ angle capacity
- CME 45 SKID Mount
- 55 CME Track Mount
- (2) GMC C-7500 Water Truck
- (16) 1 Ton Support Trucks
- (10) Various smaller support trucks
- 100’ of 2.25” HSA, 300’ of 3.25” HSA
- 400’ of 3.25” HSA
- 600’ of 4.25” HSA
- 150’ of 6.25” HSA
- 200’ of 3” NW Casing
- 250′ of 6″ Casing
- 1,100’ of 4” HW Casing
- 6+ Casing Advancers
- 2 – 10’ NW Core Barrels
- 4 – 10’ NQ3 Core Barrels (Wireline)
- 9 – 10’ HQ3 Core Barrels (Wireline)
- 2 – 5’ PQ Core Barrels (Wireline)
- 8 HQ3 Double Packer Systems w/ Transducers
- 3 NQ3 Double Packer Systems w/ Transducers
- 8 Deck Over Trailers
- 4 Troll Systems
- 36’ x 20’ Spud Barge and Support Boat
Drilling Capabilities
- Drilling to 400’ on land and in water
- Packer Testing (w/ VW Transducers)
- Rock coring
- Hollow stem auger drilling
- Solid flight auger drilling
- Field Classification (ASTM D2488)
- Piezometer installation (standpipe & vw)
- Mud rotary drilling
- Goodman Jack
- Vane Shear
- Air rotary drilling
- Borehole Extensometer
- Hand penetrometer testing
- Inclinometer casing installation
- Rock core drilling/extraction
- Downhole pressuremeter / dilatometer
- SPT soil sampling
- Shelby tube sampling
- Boring logs
- Test pit excavation
