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HDD Wells, Horizontal Well Rehab… and a Hurricane!

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Mix an ongoing remediation project with new well construction, old well rehab, conveyance lines and railroad crossings, then toss in Hurricane Irma, and what do you get? A successful project!

DTD recently completed a unique project in Georgia for one of our national clients. Remediation at this busy industrial site has been underway for several years, and the consultant had determined that additional efforts were needed at the site. Among the required activities were the installation of a horizontal groundwater extraction well to extend the treated area, and rehabilitation of three existing horizontal wells that had been installed as long as 10 years ago.

Rig’s eye view – conveyance line installation

In addition, the project required the installation of a long conveyance line to transport the water from the new horizontal extraction well to the treatment plant. Starting on this task while the well screen was being assembled, DTD installed 1700 feet of conveyance line, split into five segments ranging from 250 to nearly 700 feet in length. An additional 400 feet of line was installed beneath active rail lines. The conveyance line installation included the placement of a half-dozen vaults with cleanouts for future maintenance. During this early phase of the project, Hurricane Irma made landfall in the US, pushing severe weather to the project site. In advance of the storm, DTD and the consultant prepared the site to withstand heavy rain and winds, shutting down the project for two days. After the storm had passed, the project restarted, with the earlier precautions having prevented any damage to installed lines, stockpiled materials, or equipment.

Well screen assembly along side of a site access road

Following the conveyance installation, the DTD crew began installation of the 630 foot extraction well. A design that included carbon steel, stainless, and HDPE components, of two different diameters, the well installation required drilling of a pilot bore and multiple reaming passes. DTD used our Vermeer 24×40 rig for drilling and installation, using a walkover locating system. Working closely with the consultant to optimize the bore path, small changes were made to avoid locating near a security fence and to improve the well head locations.

The final phase of the project was to develop the new well and inspect and re-develop the previously installed wells. All of the previous wells had experienced a gradual degradation in performance – interestingly, the oldest well, some 10 years in operation, was performing better than more recently installed ones, possibly as a result of inadequate initial development of wells installed with bentonite drilling fluid. None of these wells had been installed by DTD.

To begin, DTD performed a video inspection of the wells to document their current state, followed by multiple jetting passes to clear the screen of sediment and potential blockage. When the return water from the jetting had stabilized in turbidity, the wells were reinspected, showing significant improvement.

In total, the project was completed in 28 days – this included 630 feet of new horizontal remediation well installation, 1700 feet of conveyance lines, 400 feet of railroad crossing, the redevelopment of three existing horizontal remediation wells – and a major hurricane.