Frequently Asked Questions
What are Vertebrae™ horizontal nested, segmented well systems (Vertebrae Well Systems™) and how do they differ from traditional single horizontal wells?
- Vertebrae Well Systems are a multi-function engineered set of nested, segmented subsurface wells oriented horizontally. Each well is isolated from the others in the same horizontal borehole and separately plumbed to the surface. The Vertebrae well system design reduces or eliminates the potential for preferential pathway influences associated with single horizontal wells.
- Vertebrae well systems allow users to complete site assessments and implement a wide variety of remedial actions regardless of site obstacles. This includes the surface and subsurface infrastructure in built or natural environments, security constraints (industrial or military) and issues with access to adjacent properties.
- Vertebrae well systems can eliminate the need for an extensive network of vertical wells and site trenching, and they also limit or eliminate business disruption along with providing a safer work environment.
- The versatility of Vertebrae well systems allow them to be used for extraction or injection of fluids or gases. This make them suitable for assessment or treatment or often both.
How are the Vertebrae Well Systems delivered to the project site?
- Vertebrae Well Systems are pre-manufactured at the factory and delivered to the project site ready to be installed in a “protective” conduit on either an eight or a ten-foot diameter reel.
Who installs the Vertebrae Well Systems?
- The Vertebrae Well systems are installed by local licensed driller’s, experienced in the installation of horizontal wells and are familiar with the specific regional geologic and local drilling conditions. EN Rx personal are on every project site to oversee the installation of the Vertebrae Well Systems, to ensure that the wells were installed correctly, developed, grouted and completed. This operation culminates in final field testing and sign-off.
What can Vertebrae Well Systems be used for?
- Vertebrae Well Systems can and have been used for many aspects of site characterization and remediation. Vertebrae Well Systems have been implemented for the injection of oxidants and reductants, implementing installation of AS/SVE systems, vapor mitigation, biosparging, and for pump and treat applications. Vertebrae Well Systems have the capability to be more than one tool in that they can be used for both data collection followed by an appropriate remediation strategy as required.
How do you design spacing and well segment lengths?
- The lengths and spacing of the individual well segments are based on the desired function of the well system, along with the estimated ROI for treatment. With direction from the Engineer of Record and/or consultant we collaborate to design the Vertebrae Well Systems based on the desired remedial action plan. “System Control is the Goal”.
How is the Radius of Influence (ROI) determined?
- The ROI is largely based on prior vertical site characterization data and site specific geologic/lithologic information. In some cases, a pilot Vertebrae Well System is installed and used to determine ROI prior to the installation of the full remediation system. Detailed site assessment data is critical to the Vertebrae design. In most cases it is easy to allow for complete ROI overlap and excellent coverage based on the efficiency and number of segments possible in a single Vertebrae Well System.
How is the size of the wells determined?
- Well diameter is determined based on treatment function (i.e. injection vs. air sparging vs vapor extraction) as well as the total length of the well. The size may be adjusted to account for pressure/friction loss along the well segment. Typical sizes range from ½-inch to 2-inches with conduit sizes ranging from 2-inches to 5-inches. Additional customizable capabilities are available based on specific project requirements as we manufacture our products in our own facility.
What type of flow rates can be achieved with the Vertebrae Well System?
- Our Vertebrae Well Systems can accommodate most flow rates. We balance the desire to have higher flow rates with the need for control. Since our Vertebrae well system designs are fully customizable, we can build a Vertebrae Well Systems based on the specific site design requirements. Flows will be dependent on the site lithology and conveyance tubing size.
- Currently, we have always outperformed the requirements provided by our clients for flow. A few examples include:
- At a project site where the client wanted a sparge curtain with segments that produce 30 cfm of air in 7 segments. Our well segments produced 40 to 50 cfm each.
- For a site in Colorado, a client designed an SVE system for 30 cfm per point, and our Vertebrae well segments each performed at 35 cfm.
- For pump and treat site where the client designed a system for 1.5 gpm and our well segments produced 2.3 gpm.
- Keep in mind, the total flow rates of the system can be extensive and robust, for instance, the air sparge curtain above was supplying 290 cfm in a 40 ft curtain. Even a small well system design using 1/2” tubing over 700 ft long was able to use 18 wells to inject 13 gpm.
How many well segments can be put in one bore?
- The number of well segments in a single bore is dependent on the type and size of the wells being installed and is completely customizable based on the design specifications. Currently our design information indicates as many as 30 segments can be achieved.
- To date, the largest number of well segments that we have installed in one bore has been 18 segments and we have installed as few as two.
Are there any limitations on the drilling location?
- The options from horizontal drilling are unique as the plume can be approached from many different directions. Several factors come into play to find the best drilling location:
- The footprint of the typical drilling equipment requires approximately 25 feet X fifteen feet of space. If a larger drill rig is required to reach the desired depth/length or geologic formation more set-up space will be necessary.
- The typical setback in order to reach the desired depth is generally a 3:1 slope, which is where the drill rig is set up. This is unique in comparison to other operations that can require a 5:1 or greater slope.
- Surrounding utilities play a significant role in the feasibility of the proposed drilling location and must be marked for type, location and depth.
How are Vertebrae Well Systems developed?
- Vertebrae wells are developed by surging and pumping the well segments until clear (for wells below the water table). However, with independent control, we can develop the all well screens simultaneously with a manifold. Due to the high performance of the Vertebrae well screens, the development process only takes a fraction of the time when compared to a traditional horizontal well installation.
Can Vertebrae Well Systems be installed blind?
- Yes, Vertebrae well systems can be installed blind. In 2019, 63% of our Vertebrae well systems have been installed blind.
What is the size of the entrance and exit pits associated with the typical entrance/exit horizontal borehole installation?
- This is highly variable, dependent on the size of the borehole and how many boreholes are used in the same pit. However, typically, the entrance pits are usually 1 to 2 feet deep and 2 feet x 3-feet in area but can be larger. The exit area in general is as small as 1-foot x 1- foot.
How long does it take to install a single Vertebrae Well System?
- This is highly variable and is dependent on total bore length, depth, site lithology and conduit size. On average, a common exit/entrance bore with a Vertebrae Well System installation takes three days. The first day is typically used for equipment delivery, set-up, layout, site preparation and staging, the second day to drill and install the Vertebrae Well System and the third day is used to grout and develop the well segments.
How are the well segments isolated?
- A proprietary expansive grout seal is injected in discrete intervals between the well segments to seal the borehole pathway and isolate the independent well segments.
- The isolation has been verified on several sites using pressure and vacuum testing.
- In addition, the contaminant isocontours developed from sampling the individual well systems indicates true separation. Information presented to us from our clients shows that the users control of the systems has been remarkable and worked in better treatment of their project sites.
- Recently, we also obtained visual proof of grout integrity via an examination by Aestus’ GeoTrax system that is designed to effect subsurface imaging.
How much Investigation Derived Waste (IDW) is generated?
- This is highly variable and is dependent upon the lithology, bore size, bore total length, and bore type. An estimate of the volume of IDW is provided based on bore hole diameter and total length which can be used for planning purposes. The borehole diameter is minimized to reduce waste.
How are the Vertebrae Well Systems maintained?
- Typically, the Vertebrae well systems have not required extensive maintenance routines. If necessary, the wells can be surged with air, water, or the appropriate chemical to alleviate any clogging that may have occurred. The extensive scrubbing or surging associated with the initial well development of a typical single, monolithic horizontal well installation is not required with the Vertebrae Well System. This is a result of the cleaner installation process using a sleeve, and the larger open area that allows better communication with the lithology and easier development.
How accurate is the HDD bore on depth?
- The available tracking technology is highly sophisticated and is precise to within inches. There are several variables that can affect this including total depth, surrounding ground interference, and the ability to walk over the bore path.
Are Vertebrae well systems PFAS-Free?
Currently there is no certification for PFAS-free wells in the industry. However, EN Rx is the first to address this issue. We now can provide a Certified PFAS-Free Well Systems for the cost of the laboratory verification. We test what we sell before we ship and will provide a copy of the laboratory analysis.
What is the longest Vertebrae Well System installed in a single borehole?
- Currently to date the longest 776 feet. Scheduled to be installed by the end of 2017, is a 1,071 foot well system with a total build length of 1,145 feet. There will be 18 independent well segments in the well system.
- Although longer Vertebrae wells are possible, there are many benefits to dividing very long plumes into parts or making transects. First is cost, two 700 foot bores using smaller rigs are less expensive than one 1,200 foot bore. Frictional losses also come into play as well as the ability for more control. In addition, site space and ease of installation are factors considered to make this judgement. However, we know there will continue to be situations that require long wells and longer blind wells and new information will be regularly added to this site.
What is the deepest a horizontal well can be installed?
- This is highly dependent on geologic factors, but depths over 100 ft are possible.
Can you drill deeper than the suction limit of the water, i.e. beyond 30 ft bgs?
- Yes, if development is not required for injection or air sparging, this is completed similar to our typical installation.
- Where sampling and water collection is required and where the water table is greater than 30 ft bgs, we can use special double valve pumps to develop and purge the wells. This is slower than normal development but just as productive.
Why does a blind bore costs more if it is shorter?
- A blind bore requires a “trip in’/ trip out” installation doubling the drilling. It also requires a larger bore to accommodate the circumference of the drill rods and conduit. This results in a third pass to reem out the initial pilot bore prior to installation. This requires more time and thus costs more.
Can we sample as we go?
- Soil sampling during drilling has been a “trip in/‘trip out” based technology for a long time. It has been cost prohibitive in many cases. We are working on technology to allow several samples to be collected as we drill to provide lithologic and quantitative data.
What are the injections limitations for reagents?
- Our well segments out perform other typical wells used for injection. Vertebrae well systems essentially can push any liquid, emulsion or particulate suspension, but there are limits regarding gels and other very high viscosity materials or those with large solid loads or particulates.
Are Vertebrae Well Systems nested wells?
- Yes, fundamentally they are multiple well screens each with individual risers and individual well seals between each screen providing a multiplicity of well zones. However, there are a few major differences between vertical nested wells and Vertebrae Well Systems.
- First there are the dimensions; there can be a significantly greater distance between well zones offering excellent seals and more coverage. This discreteness is adjustable but, in most cases, there is from 2 to 10 times more more separation between screens as typical nested wells.
- The second major difference is hydraulic in nature. The well systems are generally installed in a single stratigraphic horizon. This means there is no concern of transporting the containment to a different zone but only concern transporting the contaminant along the same zone. This concern is minimized by the distance of travel and the competent seals set in place.
- The third is the quantity of wells. When installing one system in place of 10 or even 20 vertical wells, we have significantly reduced the risk of creating a contaminant pathway. Furthermore, the drilling location is typically placed away from possible sources. These factors effectively reduce the risk by orders of magnitude.
- In addition, there is no drawdown when installing the wells in the same manner.
In Summary: Why use Vertebrae Well Systems?
Vertebrae Well Systems offer multiple advantages to traditional vertical wells. They can be installed in difficult to access areas as itemized above. They can be placed on the most effective horizontal plane for a chosen remediation strategy, creating more efficient well segment design. With one bore location per Vertebrae well system, all the individual well segments are separately plumbed to the surface and located in one discreet area, so disturbance is minimal during on-site activities and eliminates the need for additional trenching.
ENVIRONMENTAL INNOVATION LIKE NO OTHER
Our expertise is in filling data gaps and delivering treatment reagents with segmented well systems. We take assessment and treatment to a new level, transforming Site Conceptual Models and paths to closure.
EN Rx SUPPORT PLATFORM (SP)™
Used with Vertebrae or other subsurface infrastructure. SP is a self-contained, solar-powered, remotely operating and communications-ready device for site assessment and remediation. It is programmable for pulling gas/water samples for analysis or actual treatment and in reverse can inject reagents.