Active excavation on an Idaho drainfield project.

Drainage systems overview

Advanced drainfield support for sites that need a better-fit system

DAG Supply works on advanced drainfield projects where a conventional solution is not the answer. We supply materials, install when needed, and help projects stay coordinated from the field side.

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Good fit when

Poor soil or limited site conditions
Replacement and upgrade work
Engineer-led designs that need execution
Projects where footprint matters

Authorized Eljen GSF installer

DAG Supply installs the Eljen Geotextile Sand Filter (GSF) system — an advanced alternative leachfield solution. Manufacturer details at eljen.com

When this kind of system is used

The right fit is usually about site pressure, not brochure language.

Poor soil or limited site conditions

Sites with tight layouts, restrictive soil conditions, or other physical limitations often need an alternative approach instead of a conventional trench layout.

Replacement and upgrade work

When an existing system is failing or the property is being brought into a new requirement, advanced drainfield options can become part of the path forward.

Engineer-led designs that need execution

Some projects already have the design direction but still need a local supplier or installer who can execute the work cleanly.

Projects where footprint matters

Alternative systems can help when the project is trying to solve around space, geometry, or long-term field performance concerns.

Simplified system view

Two treatment stages drive the conversation.

The Eljen GSF system treats effluent in two zones before it reaches the native soil. Understanding this distinction is what helps you see why the system is permitted in situations where a standard trench-and-gravel approach cannot pass.

Simplified cross-section — Eljen GSF system. Final installation must follow current Eljen design and installation guidance and applicable local requirements.

Zone one

Treatment begins in the module

Effluent is distributed across the module where the geotextile and plastic core create the surface area needed for aerobic treatment before it reaches the native soil.

That first stage is what makes this system different from a basic gravel trench conversation.

Zone two

Specified sand supports the soil interface

After leaving the module, the treated flow moves into a specified sand layer that promotes controlled, unsaturated movement toward the native soil.

This helps the field treat and disperse flow with less dependence on the native soil doing all the work at once.

Installation stages

What the job looks like in the field.

Module placement and pipe connection

Trench and sand bed prep

Field installation

Final grade and finish

Module and spec context

Two module sizes — same two-zone treatment logic.

The A42 and B43 modules follow the same Eljen GSF system design. Module selection depends on the layout, treatment area, and site-specific engineering requirements.

Installed along the module length with the system orientation and piping layout called for by the manufacturer instructions
Specified sand and cover fabric are part of the required system assembly
Local engineering, permit, and inspection requirements still govern the final job conditions

Final installation must follow current Eljen design and installation guidance and applicable local engineering, permit, and inspection requirements.

A42 module

4 ft x 2 ft x 7 in

A common residential module format used in many advanced drainfield applications where the layout and treatment area fit the project needs.

4 ft length

B43 module

4 ft x 3 ft x 7 in

A wider module option used when the project needs a different layout strategy or higher-capacity treatment footprint.

4 ft length

What DAG handles

Supply, field execution, and the handoff points around the job.

Supply

Material sourcing and delivery

Modules, specified sand coordination, pipe, clamps, and required cover fabric can be lined up for contractor or owner-managed jobs.

Install

Installation to system requirements

Our crew can handle trench layout, sand bed prep, module placement, piping, cover fabric, and backfill with the system requirements in mind.

Coordinate

Project sequencing and field clarity

We help reduce handoff friction between homeowner, builder, excavator, engineer, and field crew so the job does not lose momentum.

Equipment and fleet ready for drainfield and excavation work.

Common project types

Work that usually comes through this page

New drainfield installationReplacement or failing system workPermit-driven upgrade projectsContractor supply and delivery supportEngineer-referred system installsTight-lot or constraint-heavy sites

Start with the field reality

The best first step is usually a project review, not a guess.

Send the location, job stage, and whether you need supply, install, or coordination help. We will point the project toward the cleanest next move we can.

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Talk to DAG Supply

Have a site that needs a real review?

Share the location, what stage the job is in, and whether you need material supply, install help, or field coordination.

Start a project review Call 208-565-0228