A recent project location on the eastern end of Long Island in the Hamptons, NY, presented significant challenges with the 7’ diameter drilled shafts. MATRIX Construction Products was able to provide solutions to create a successful client experience.
SITE GEOLOGY: The geology on this project consisted of sands, silts, and gravel seams (peas sized to 3” minus) containing brackish water.
CHALLENGE
There were two locations of the drilled shafts that proved to be problematic. Approximately 65’ below group surface, multiple layers of pea-sized to fist-sized gravel were encountered. The boreholes would collapse at these zones, making it impossible to advance to the total depth of 120’ and 130’, respectively. The larger formation solids encountered were not expected based on soil boring reports that were used to estimate the drilling project. To maintain borehole stability and control slurry loss, the drilling came to a standstill. With a multiple day shutdown, the project required a fast and cost-effective remedy to resolve the problem.
MATRIX was already the slurry supplier of choice for this project and the added challenges required specialized attention. Additional products were ordered by the customer. MATRIX was able to supply a rush delivery to the project and a representative was onsite to provide hands-on attention to the client. Our representative discussed the issues that had been occurring with the site personnel. Through discussion, they were able to pinpoint the exact issues to determine the cause and develop a solution to fix the problem. It was decided that the elevated levels of brackish saltwater were degrading the slurry viscosity in the hole and the larger formation solids that were encountered required added fluid loss control and borehole stabilization for these locations.
SOLUTION
Increase the viscosity of the original mixing dose by adding more slurry polymers and additives. It was also decided to initiate fluid loss control measures that would increase borehole stability.
Before reaching the problem area depths at each location, GRID-LOCK® Polymer Expanding Additive, which is a multi-sized swellable granular polymer, was added to the borehole and mixed using drill tools. It was then allowed to hydrate for 30 minutes and block off the areas where fluid was moving, causing borehole instability.
The addition of GEO-NET® Slurry Loss Circulation Material would help to fill in the areas of fluid loss with a netting action of the hydrated fibers. A combination of the swellable polymer, hydrated fibers, and drilled solids would work to slow slurry loss and stabilize the formation so drilling could continue successfully... and it did!
Hydrated GRID-LOCK® Polymer Expanding Additive with size comparison to a quarter
Hydrated GRID-LOCK® Polymer Expanding Additive in excavated slurry coming out of the hole.
Our qualified team at MATRIX provided onsite assistance for the overnight drilling, monitored the addition of products, and assisted in the ordering of addition product. With the use of BIG-FOOT® Polymer Slurry, combined with GEO-NET® Slurry Loss Circulation Material and GRID-LOCK® Polymer Expanding Additive it provided superior stability in the coarse permeable formations.
The ORIGINAL mixing dose of product to achieve a fluid viscosity of 130+ sec/quart:
M-BOOSTER® Dry pH Adjuster
100 lbs per 19K gals tank batches
FORTIFY® Slurry Loss Additive
75 lbs 19K gals
BIG-FOOT® Polymer Slurry
105 lbs 19K gals
The NEW mixing dosage of product to achieve a fluid viscosity of 230+ sec/quart:
M-BOOSTER® Dry pH Adjuster
150lbs per 19K gals
FORTIFY® Slurry Loss Additive Slurry Loss Additive
125lbs 19K gals
BIG-FOOT® Polymer Slurry
175lbs 19K gals
Addition of fluid loss control/stability measures included:
GRID-LOCK® Polymer Expanding Additive
40 lbs per 10’ of drilling in trouble zone
GEO-NET® Slurry Loss Circulation Material
60 lbs per 10’ drilling in trouble zone
MATRIX personnel being easily accessible to the client regarding the issue, quickly traveling to the site, providing a strategic plan of action, and implementing that plan, created a positive outcome for our client. Both problem locations were drilled quickly to final depth in one eight-hour overnight shift.