How to Design With Duraslot

Designing stormwater systems is about managing water through: capture, conveyance, storage and treatment under real-world conditions. Engineers balance challenges like grading, inlet placement, flow capacity, maintenance considerations and connections into larger, pre-existing infrastructure. Duraslot linear drains simplify the complexities by combining high-capacity conveyance with continuous surface capture all in one adaptable system. 

Use this guide for practical direction on best practices for Duraslot products. It explains key design considerations, integration options and maintenance planning that help achieve maximum performance and value from a single system.

Think in Systems, Not Components

Duraslot® and Duraslot XL are systems engineered to capture and convey built from ADS N-12 HDPE Pipe. As a result, they behave hydraulically like conventional storm pipes supporting large flow rates and long uninterrupted run lengths. Integrated slot risers allow for continuous surface inlet capture along the full length of each run. 

 Typical Trench Drain vs. Duraslot Layout

Start a strong design by placing a single run of Duraslot or Duraslot XL in the middle or to the side of a broad drainage area. Every drainage network must account for possible inflow sources like sheet flow across the surface, upstream pipe, roof leaders and other lateral connections. All of these inflows can then be integrated directly into the Duraslot run allowing multiple sources to enter a single pipe channel rather than being split across parallel systems. For instance, roof drains and laterals can tie directly into the pipe using Inserta Tee, creating watertight connections without additional structures. Flow from these sources also helps flush the line, improving self-cleaning during storms.

Multiple Inflow Sources Entering the Duraslot Backbone

Practical takeaway: Identify inflow sources early and plan to route as many as feasible into the same Duraslot trunkline. This maximizes efficiency and simplifies the network.

Duraslot products can be fabricated with neutral 2.5-inch or 6-inch slot risers, allowing the channel to follow the surface grade. However, surface grading rarely conforms to that, but these systems do. Slot heights can be customized so that the pipe and grade slope can be set independently for high design flexibility. A minimum pipe slope between 0.5 – 1% is recommended to improve flow rates and reduced build up in the pipe. Steeper slopes may be used where conditions allow, provided the difference between the grade and pipe slope does not exceed 4%.

Practical takeaway: When designing the channel, engineers should account for burial depth limits (see TN 2.11 Duraslot Burial Depth and Backfill Conditions, Tables 1 – 2). As pipe slope increases, allowable run lengths may shorten due to the more rapid increase in slot riser height. In practice, slope selection should be evaluated early in layout development balancing hydraulic performance, surface grading and constructability over the full length of the run.

Checking Inlet Capacity – Selecting a Grate   

Inlet capacity is rarely the controlling factor in Duraslot design because the continuous inlet provides substantially more open area than a point inlet. For example, a 15-foot section of open-top Duraslot offers roughly 315 square inches of opening, comparable to a 2-foot by 2-foot inlet and most installations are longer. Design decisions are driven by conveyance capacity and grading, not inlet limitations.

With inlet capacity generally abundant, grate selection becomes more about matching site needs than maximizing capture. Engineers should consider load class requirements, ADA constraints, aesthetic preferences and anticipated debris conditions when choosing a grate design. There are multiple grate profiles and slot riser combinations to align inlet performance with the functional and visual demands of the site.

Testing under real-world conditions is important to demonstrate how the products really perform. We partnered with Utah State University's hydraulic testing facility to evaluate Duraslot and Duraslot XL's capacity to handle water flow under a variety of scenarios. Individual testing on different grates provides accurate data on inlet capacity and efficiency. 

Practical takeaway: On-grade inlet performance is influenced by approach velocity, flow depth and grate geometry, which is more difficult to model than a sag condition. Use the inlet capacity data as guidance rather than a guarantee, with engineers evaluating how closely their site conditions align with the tested scenario and applying engineering judgment where conditions differ.    

Plan for Maintenance and Longevity

Cleanout points remain important for linear drain maintenance regardless of the design and should be placed every 50 to 100-feet, depending on site conditions and expected loading. Nyloplast structures are well suited for this role, providing a durable solution for easy access into the system. These access points allow routine jetting or inspection and are especially valuable on longer or flatter runs where flow velocities may naturally be lower.

Surface debris is another practical consideration in long-term performance. In environments with heavy foliage or debris, a clogging factor of up to 50% is recommended when evaluating inlet capacity and selecting wider grate options, such as Duraslot XL grates, to better resist blockage and maintain surface intake even when partially covered. For more information on maintenance, the Duraslot and Duraslot XL Maintenance Guide has useful guidelines for system upkeep. 

Practical takeaway: Design the system to maintain self-cleaning velocities, space cleanouts strategically, and select grate widths appropriate for debris loads. This ensures reliable long-term performance with fewer maintenance intervals.

Let Linear Drainage Systems Work for you

A Duraslot system unifies surface capture, subsurface conveyance and connectivity into a single, pipe-driven design. Its defining advantage is flexibility within that system: slot heights, pipe diameters, slopes, grate configurations and surface conditions can be adjusted independently without fragmenting the drainage network. This allows the system to respond to real grading constraints, hydraulic demands and maintenance goals rather than forcing the site to conform to a fixed layout.

Used as the drainage backbone, Duraslot shifts design control from surface inlets to pipe design. This reduces transitions, cuts the number of structures needed, simplifies grading, and makes hydraulic behavior easier to model and verify. Because it integrates directly with the broader ADS product family, engineers can deliver a coordinated stormwater system that is adaptable, predictable, and easier to maintain over its full service life.