Turnkey HDD — Trenchless Pipe Installation

HDD — Horizontal Directional Drilling

When Trenchless Installation Is Required

There are situations where open-cut trenching is not merely inconvenient — it is technically impossible or legally prohibited. A state highway, a railway line, a river, or the protected zone of a cultural heritage site: in each of these cases, open excavation either demands months of permitting or poses unacceptable risks to existing infrastructure. Horizontal directional drilling (HDD) solves the problem differently: a borehole is driven beneath the obstacle using a steerable drill, without traffic disruption, without breaking the surface, and without large-scale earthworks.

LK Energy performs HDD as part of comprehensive EPC projects — cable installation for solar power plants, water utility networks, and telecommunications routes. A cost estimate for your project is typically delivered within 24 hours on business days.

HDD vs. Open-Cut: Key Advantages

Trenching at a congested urban intersection or beneath a highway carriageway is expensive — and not only in monetary terms. HDD differs across several key parameters:

*Indicative values. Actual durations depend on geological conditions, crossing length, pipe diameter, and site complexity.

The economic advantage of HDD is most pronounced where costly pavement, heavy traffic, or occupational health and road safety regulations make open-cut impractical.

Applications of HDD

Horizontal directional drilling is applicable across a broad range of project types:

Crossings of transportation infrastructure

• National and local highways without lane closures
• Railway lines (subject to coordination with and technical requirements of railway authorities)
• Runways and restricted-access facility access roads

Water crossings and environmentally sensitive areas

• Crossings of rivers, canals, and drainage ditches
• Installation in nature reserves or areas with park status
• Locations where earthworks are prohibited (soils under special environmental protection)

Urban and industrial developed areas

• Installation beneath building foundations and structures
• Dense urban environments where open excavation is not feasible
• Through-passage across an industrial facility without halting production

Utility types:

• Power cables 0.4 kV, 6/10 kV, 35 kV
• Fibre-optic cables (FOCS)
• Polyethylene water supply pipelines (PE 100, PE 80)
• Low- and medium-pressure gas pipelines
• Pressurised and gravity-flow sewer pipelines

The HDD Process — Three Key Phases

An HDD crossing is carried out in three sequential phases, each with its own technical requirements.

Pilot Bore

The drilling rig creates a pilot borehole along the designed trajectory. The drill head is fitted with a transmitter sonde — a walkover locating system tracks its position in real time (depth, pitch, and azimuth). The operator steers around existing underground utilities and geological obstacles. Bentonite slurry is pumped under pressure to cool the drill bit, carry cuttings to the surface, and stabilise the borehole walls.

Reaming

Once the drill head exits at the target point, the pilot borehole is enlarged to the required diameter — typically 1.3–1.5 times the outer diameter of the product pipe. Depending on geological conditions and the final bore diameter, one or more passes with progressively larger reamer heads are performed.

Pullback

The product pipe or cable bundle inside a protective casing (PE conduit or steel sleeve) is connected via a swivel and pulling head to the drill string behind the final reamer, then pulled back into the borehole as the rig reverses. The bentonite slurry reduces friction and protects the pipe from damage during pullback.

Equipment We Use

The outcome of an HDD crew’s work depends directly on the rig class and the accuracy of the locating equipment.

Drilling rigs LK Energy operates its own fleet of Vermeer HDD rigs — from compact mini-rigs for crossings up to 100 m to heavy-duty rigs for crossings of 300+ m and bore diameters exceeding 400 mm. The specific rig is selected based on the agreed scope and the site’s geological conditions.

Locating systems HDD crossing accuracy depends on the locator. We use systems that provide real-time sonde tracking within the tolerances specified in the project design.

Bentonite mixing plant Automated preparation and delivery of bentonite slurry is a mandatory component of the setup. Slurry concentration and flow rate are adjusted to suit the specific soil type.

Reamers and drill heads A full set of drill heads for different soil conditions: soft formations (clay, loam), sandy soils, and mixed conditions. Specialised tooling for rock inclusions is available when required.

Bore Diameters, Depths, and Crossing Lengths

HDD technical capabilities depend on the rig class and the geological conditions at a specific site. The table below shows indicative ranges for typical crossings:

*Parameters are indicative. Achievable values are confirmed after geological analysis and bore path engineering.

Installing a single 10 kV power cable in a PE conduit typically requires a mini or mid-size rig. Bundled installation of multiple conduits or a large steel sleeve calls for a mid-size or large rig.

Geological Conditions and Their Impact on HDD

Geology is the primary factor that determines the complexity, cost, and methodology of an HDD crossing.

Favourable soils Clay, loam, and medium-density cohesive soils represent optimal HDD conditions. Borehole walls are stable, the bentonite slurry maintains the bore shape effectively, and drilling rates are high.

Moderate complexity Sand and sandy loam require higher bentonite concentrations to stabilise the bore. The risk of wall collapse increases at greater depths. Careful fluid engineering is essential.

High complexity Limestone, sandstone, and rock inclusions require specialised drill bits, additional time, and generally higher costs. Rock outcrops call for pre-assessment through exploratory boreholes.

Additional risks

• Aquifer horizons — may lead to borehole instability
• Undisclosed underground utilities — risk of damage; mitigated by potholing prior to commencement
• Fill material and industrial waste — unpredictable bearing capacity and composition

This is precisely why a geotechnical site investigation is not optional — it is a mandatory element of HDD preparation.

Project Preparation — What Comes Before Drilling

A quality HDD crossing begins well before the crew mobilises to site. A typical pre-construction cycle includes:

1. Geotechnical investigation — site exploration (exploratory boreholes or ground-penetrating radar survey), analysis of soil conditions
2. Topographic survey — confirmation of surface relief and the location of existing underground utilities (cables, pipes, manholes)
3. Bore path engineering — Bore Plan calculation: entry and exit angles, depth of cover, radius of curvature (minimum bend radius is governed by applicable standards for each pipe type)
4. Coordination with infrastructure owners — Ukravtodor, railway authorities, gas distribution companies, water utilities, municipal services — depending on the nature of the obstacle
5. Site preparation — rig setup area, exit point, containment for bentonite and cuttings
6. Regulatory approvals — submission to relevant supervisory authorities for high-complexity projects

Project Timeline

The overall duration of an HDD project comprises several elements, and a fixed timeline cannot be stated without knowledge of the specific site. An indicative breakdown:

• Geotechnical investigation and engineering design: 1–3 weeks depending on complexity
• Permit approvals (road or railway crossings): from 2 weeks to 2–3 months — the most unpredictable element
• Drilling operations (for a typical 100–200 m crossing): 2–5 working days*
• Pipe pullback and completion works: 1–2 days
• Project handover and as-built documentation: 1–2 weeks

*Depends on bore diameter, geology, and the number of reaming passes required.

The critical path is typically the permit issuance timeline from road or railway authorities — this process governs the overall project schedule and is initiated in parallel with engineering design.

HDD Costs — What Drives the Price

Publishing a fixed price per metre for HDD would be misleading to a client. The actual cost of a crossing depends on a combination of several key factors:

• Pipe diameter and type — the larger and heavier the product, the more powerful the rig and the greater the number of reaming passes
• Crossing length — longer crossings increase bentonite consumption and drilling time
• Geological conditions — rock formations can increase the price by 1.5–3× compared with clay
• Depth of installation — affects tool selection and borehole stability
• Permitting complexity — Ukravtodor and railway crossings carry separate fees for technical conditions
• Urgency — priority mobilisation or winter-season work objectively increases the budget
• Existing utility congestion — a dense underground corridor requires reduced drilling speed and additional potholing

*All cost estimates are provided solely based on a site inspection and review of the technical specification. Prices are exclusive of VAT unless stated otherwise.

To receive an estimate for your crossing, complete the form at the bottom of this page. A response is typically provided within 24 hours on business days.

The LK Energy Approach

Geotechnical assessment before drilling — not after We do not mobilise to site without a prior soil investigation. This protects against two common failure scenarios: an unexpected rock horizon mid-crossing, or a frac-out (bentonite surface breach) caused by an unstable sand layer.

In-house crew — no subcontracting All work is performed by certified HDD rig operators, not subcontracted to third parties of unknown competency. This directly affects navigation accuracy and adherence to the designed bore path.

Integration with electrical and solar EPC LK Energy is an EPC contractor with over 20 years of experience in power engineering (since 2005). For solar plants of 1+ MW, an HDD crossing beneath a highway to the grid connection point is part of a single contract — not a separate subcontract with an independent third party.

Construction all-risk insurance Upon client request, we arrange construction and erection all-risk (CAR/EAR) insurance in accordance with the contract terms — including for public-sector projects where this is a mandatory requirement.

Public procurement experience Preparation of as-built documentation, operating within the ProZorro procurement system, and assembling tender packages for municipal clients and water utilities are standard LK Energy practice, not an exception.

Frequently Asked Questions

How much does HDD cost per metre? The per-metre price for the same pipe type can vary by a factor of 3–5 depending on geological conditions, bore diameter, and permitting complexity. We do not publish a rate card — it would not reflect the actual cost. We provide a project-specific estimate.

Can HDD be performed in rock? Yes, but it requires specialised tooling and significantly affects cost and schedule. A preliminary geotechnical investigation is mandatory for an accurate assessment.

What is the minimum bore diameter for HDD? For cable installation in a protective conduit, the practical minimum is an outer pipe diameter of 50 mm (for example, a PE conduit for fibre-optic or small-gauge cable). The final selection depends on the type of utility being installed.

What permits are required to start an HDD crossing under a road? The standard package includes a permit from the road authority (Ukravtodor or the local asset owner), technical conditions for the crossing, engineering documentation, and an approved Bore Plan. The list may expand depending on the type of project.

Will HDD damage the road or pavement surface? When executed correctly — no. Operations are conducted from the entry pit and exit point, both located outside the paved surface. The only risk is a frac-out caused by excessive bentonite pressure; this is prevented by selecting the correct drilling fluid parameters and maintaining pressure monitoring.

Is a geotechnical report required for HDD? For simple crossings in well-characterised soils (based on data from adjacent projects) existing records are sometimes sufficient. For complex crossings — large diameters, lengths of 200+ m, or known rock zones — a full geotechnical investigation is mandatory.

How does HDD differ from pneumatic piercing (mole)? A pneumatic piercing tool (mole/earth bullet) is an unguided method with no trajectory control: the tool compacts the soil rather than removing it, and neither depth nor alignment is guaranteed. It is suitable only for short crossings (up to 30–40 m) in soft soils at small diameters. HDD provides precision navigation, a controlled bore path, and is applicable to any diameter and complex site conditions.

Who is liable for damage to existing utilities? Liability is defined in the contract. To minimise risk, potholing at critical locations and mandatory cross-referencing with as-built utility plans from asset owners are carried out before work commences.

Request an HDD Quote

To prepare a commercial proposal, we need the following information:

• Type of utility (power cable, water main, gas pipeline, fibre-optic cable)
• Nature of the obstacle (road, railway, river, built-up area)
• Approximate crossing length and required depth of cover
• Site address or coordinates
• Availability of geotechnical data, or need for a site investigation

Complete the form below — provide your full name, phone number, email address, site address, and a description of the scope (attach a technical specification or crossing sketch if available). An estimate is typically provided within 24 hours on business days.

Alternatively, contact us directly — see the Contacts section.

Related services: cable installation for solar power plants and EPC electrical works.