Field Notes
Multiple Utilities in One Directional Bore: What Oklahoma Contractors Need to Know
By Trinity Boring Solutions · Yukon, Oklahoma · 5.0★ from 49 reviews
One of the most practical questions on any Oklahoma boring job is whether multiple utilities can go in through a single bore. The answer is yes – with planning. Combining multiple utilities in one directional bore saves mobilization cost, reduces site disturbance, and can future-proof a crossing by including spare conduit for later use. But there are rules about which utilities can share a bore, how to size the hole correctly, and what separation requirements still apply. This guide covers all of it.
How Multi-Product Bore Pulls Work
In a multi-product pull, all pipes or conduits are assembled into a bundle at the exit pit and pulled back through the bore hole simultaneously. The bundle is attached to a swivel and pulling head that connects to the drill string. As the drill retracts, the entire bundle travels through the reamed hole in one pass. All products enter and exit at the same elevation on both ends.
The preparation work is done at the exit pit before the pull begins. Installers lay out all the pipes, attach them together with bands or straps, and rig the bundle to the pull head. The reamed hole must be large enough to pass the full bundle cross-section including the pull head hardware. Once the pull begins, the bundle moves through continuously without stopping.
The drilling fluid that filled the hole during boring provides lubrication for the pullback and helps the bundle slide smoothly. Getting the fluid mix right for the soil type is especially important on multi-product pulls because the added weight and friction of a larger bundle puts more load on the drill string during pullback. An experienced crew manages pull tension closely throughout the process.
Which Utilities Can Share a Bore in Oklahoma?
Telecommunications conduit, electrical conduit, and water lines commonly share bores. Gas lines almost always require a dedicated bore under Oklahoma utility codes and gas regulations because gas and electric together in one hole is prohibited by most codes. Always check the applicable code – National Fuel Gas Code, NEC, and local utility company rules – before combining any utilities.
The National Electrical Code restricts certain wiring methods in the same raceway. The National Fuel Gas Code has requirements for separation between gas piping and electrical systems. Oklahoma utility owners – OG&E, ONG, OEC, and others – may impose additional requirements beyond the codes. Confirming co-location rules with each utility owner before designing a multi-product bore is the only safe approach.
Common combinations that work: two electrical conduits for different circuits, electrical conduit plus a spare empty conduit, fiber conduit plus spare conduit, water service line plus empty spare conduit. The spare conduit does not carry any utility and has no incompatibility issues – it is simply an installed pathway for future use. See our fiber optic boring guide for more on conduit sizing for communications installations.
Sizing the Bore Hole for Multiple Products
The reamed bore hole must be at least 1.5 times the outside diameter of the product bundle. The bundle diameter is calculated by modeling how the individual pipes nest together – two pipes of equal diameter laid side by side have a bundle width of roughly two pipe ODs. Proper sizing allows drilling fluid to circulate during pullback and prevents the bundle from getting stuck.
Bore hole sizing for multi-product installs is where experience matters more than for single-pipe bores. An undersized hole causes the bundle to stick, which can leave all the pipes stranded underground. An oversized hole wastes reaming time and drilling fluid without adding benefit. The contractor calculates the bundle cross-section, selects the reamer size, and verifies there is enough torque and pullback capacity on the rig to handle the larger diameter.
Oklahoma clay soils typically hold bore holes well during multi-product pulls. Sandy or loose soils may require higher fluid viscosity to prevent the hole from closing on the bundle during pullback. The type and condition of soil along the bore path affects both the reaming strategy and the fluid program for a multi-product installation.
The Case for Spare Conduit on Every Bore
A spare conduit – an empty pipe installed alongside the primary product – costs almost nothing extra when added to an existing bore pull. It gives you a pre-installed underground pathway for a future utility without ever having to bore again. On residential bores this might mean a 1-inch spare conduit alongside a water line. On commercial bores it might mean two or three spare conduits for future communications or power needs.
The marginal cost of adding a spare conduit is usually under 10 percent of the total bore cost. The cost of a future bore to cross the same obstacle – under the same driveway, the same road, the same landscape feature – is 100 percent of a new mobilization. Oklahoma property owners who have added a building, changed their electric service, or run new internet service to a barn understand how quickly that second bore becomes necessary.
Standard practice for new construction in the Oklahoma City metro is to include at least one spare conduit on any bore under a driveway or road crossing. For commercial boring projects, developers routinely install spare conduit banks because the cost to retrofit later – with finished parking lots, landscaping, and occupied buildings above – is prohibitive.
Depth and Cover Requirements When Combining Utilities
Each utility in a multi-product bore must still meet its individual minimum cover requirement. Gas service lines in Oklahoma typically require 12 to 18 inches under private property and more under roads. Electrical conduit has NEC depth requirements. Water lines have minimum depth rules. The bore must be deep enough to satisfy the most restrictive depth requirement among all utilities in the pull.
This is a detail that catches contractors off guard on multi-product jobs. If you plan a bore at 24 inches of cover for a water line and add electrical conduit that requires 24 inches under non-paved areas and 18 inches under a road, the water line depth satisfies both. But if you are running conduit for a gas line requiring 24 inches and a water line also at 24 inches, the bundle depth is fine. If one utility required 36 inches, the entire bore would need to run at 36 inches throughout.
Our depth and soil guide for Oklahoma boring covers the cover requirements by utility type and surface condition. Planning depth correctly from the start prevents having to re-bore because one product in the bundle was too shallow.
How Cost Savings Work on Multi-Product Bores
The primary savings in a multi-product bore come from combining mobilization and setup costs. You pay to move the rig once, set up the fluid system once, drill the pilot bore once, and ream once. The incremental cost of pulling a second or third product through the same hole is small compared to the full cost of a second bore. Savings typically range from 30 to 60 percent on the second utility compared to a separate bore.
A realistic breakdown: a 100-foot single-product bore might cost $800 to $1,200 depending on soil and product. Adding a spare 1-inch conduit to that same bore pull adds $80 to $150 for the conduit material and a slight increase in pull-back time. Running that same spare conduit as a separate future bore would cost $800 to $1,200 again. The math strongly favors including it now.
When evaluating a quote for a boring job, ask the contractor what the incremental cost is to add a spare conduit or a second product. Compare that to the full cost of a future separate bore. Almost every time, adding it now is the rational economic choice. See our full directional boring cost guide for Oklahoma for a breakdown of how costs are structured.
Planning a Multi-Product Bore: Key Questions to Answer First
Before committing to a multi-product bore, confirm: which utilities are compatible for co-location under applicable codes, the OD of each product and the resulting bundle size, the depth requirement for each utility, the utility owner’s approval if the lines are owned by a public utility, and whether rig capacity is sufficient for the larger reamed hole and heavier pull.
A pre-job conversation with the boring contractor should cover all of these points. Bring a sketch of what you are trying to install, the distances involved, and any information about what utilities are already in the ground along the bore path. From there the contractor can confirm compatibility, size the bore, and give you an accurate quote that compares single and multi-product options.
Trinity Boring Solutions plans multi-product bores on residential and commercial projects across Oklahoma regularly. Whether you are running water and fiber to a new structure, adding a spare conduit to a trenchless water line installation, or setting up conduit banks for a new commercial development, we can design the bore to make your investment count for the long term.
More from Trinity Boring Solutions
Trinity Boring Solutions is one of the most trusted directional drilling companies in Oklahoma, with 24/7 crews statewide since 1965. New to the process? Start with our guide to horizontal directional drilling (HDD), then see real numbers in our directional boring cost guide.
Frequently Asked Questions
Direct answers to what Oklahoma property owners and contractors ask us most.
Can you pull two or more pipes through one directional bore at the same time?
Yes. Multiple pipes or conduits can be bundled together and pulled back through a single reamed bore hole simultaneously, as long as the total bundle diameter fits within the reamed hole size. This is called a multi-product bore or bundled pull-back. It is common practice for running two conduits together, a water line with a spare conduit, or multiple fiber pathways in a single crossing.
Can you put gas and electric in the same bore?
Generally no. Gas lines and electrical conduit should not share the same bore hole. Most utility codes and gas codes in Oklahoma require physical separation between gas pipe and electrical systems. Each should run in its own separate bore. Water and electric conduit can sometimes share a bore depending on local utility rules, but always confirm with the utilities involved before combining them.
How much does running multiple utilities in one bore save?
Combining two utilities in one bore typically saves 30 to 60 percent compared to running two separate bores for the same crossing. You pay one mobilization, one bore setup, one fluid system operation, and one labor crew for one bore instead of two. The reaming cost increases slightly for a larger hole, but the savings on a second bore are almost always larger.
Does adding more pipes to a bore change the depth requirements?
Adding pipes increases the required bore hole diameter, which can affect the minimum bending radius and entry angle needed to achieve the planned depth. The depth requirements for each individual utility – set by code or utility owner specifications – still apply to each pipe in the bundle. The bore must be deep enough to satisfy the most restrictive depth requirement among all utilities in the pull.
What is a spare conduit and should I include one in my bore?
A spare conduit is an empty pipe included in the bore pull specifically to provide a future pathway for additional utilities. It costs very little to add when the bore is already being made and saves the cost of a future bore entirely. Oklahoma contractors and developers frequently include one or two spare conduits in residential and commercial bores to future-proof the crossing.
How do you determine the right bore hole size when installing multiple utilities?
The bore hole must be large enough to accommodate the total cross-sectional area of all products being pulled, plus clearance for drilling fluid circulation and a smooth pullback. A general rule is to ream the hole to 1.5 times the outside diameter of the product bundle. The contractor calculates the bundle OD based on how the pipes are arranged and sizes the reamer accordingly.
Can I add a utility to a bore that was already completed?
Not in the same hole. Once a bore is complete and the pipe is pulled in, the hole closes around the product. The only way to install a second utility is to bore a new path. This is why including spare conduits at the time of the original bore is strongly recommended – future needs are much cheaper to accommodate during the initial installation.
Plan your multi-utility bore right the first time. We will run the numbers for you.
Trinity Boring Solutions is open 24 hours for directional boring across Oklahoma. 9102 NW Expressway, Yukon, OK 73099.
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