To create an efficient floor plan takes a thoughtful design strategy, which is an especially important aspect in the development of membrane treatment facilities. These compact spaces need to balance the purpose of providing necessary water treatment with limiting operational challenges and supporting future expansion options.

Optimizing these sites and internal building layouts during design can lead to reduced capital and ongoing maintenance costs. Additionally, an efficient design allows operators to easily navigate around equipment areas. Retrofitting a water treatment plant requires optimization of the existing footprint and a custom-designed process layout for the chosen treatment option.

When planning a membrane softening facility, there are several main components to keep in mind during design.

Membrane Skids

Made up of an assortment of membranes and multiple arrangement options depending on required treatment, membrane skids occupy a majority of the space, driving overall facility size and design. These pre-engineered systems — which optimize the footprint, installation and commissioning of membrane softening systems — allow for minimal instruments, enhanced pipe routing and easy-to-assemble components.

During design, it’s important to think about accessibility — providing room for maintenance equipment to easily access all membrane elements. Ease of access becomes especially critical when it comes to timely, routine replacements.

As needs change, a facility should as well, which is why the design should consider and incorporate expandability options. A plant that has capacity for 9 million gallons per day (MGD) today, for example, might have a need for another 3 MGD in the future. Knowing this, and planning for it, allows for seamless expansion when the time comes.

Membrane Cleaning System

Typically, a permanently installed cleaning system cleans membrane skids periodically to maximize their useful lives. This process, however, requires a certain amount of manual operation, so if a cleaning system isn’t sized correctly, it can pose a significant challenge for the operator. Unfortunately, this system and its corresponding space requirements are an often-overlooked part of the design.

Feed Pumps

Membrane feed pumps, which are consumable parts with a limited useful life, also must be given careful consideration during the design phase. While easier to design in terms of initial sizing and placement, these typically substantial pieces require equipment such as an overhead hoist system — and, therefore, accessibility built into the plan — for efficient removal and installation. Though a plant will operate at a limited capacity during the replacement of one of its membrane feed pumps, optimization of building size for such planned maintenance will limit associated downtime.

Process Piping

Other elements easily overlooked during design are the process piping support system as well as routing design. Optimizing the process piping routing reduces the need for extensive piping runs between the existing plant and membrane equipment.

If pipes are supported on the ground, the design will need to incorporate columns throughout the building and, again, provide room to maneuver around them. Rather than mounting on the floor or to the ceiling, utilizing a structural component such as an existing wall could be a cost-effective option for the owner.

Chemical Feed System

Arguably the most challenging component of the overall design, a chemical feed system — the crux of the water treatment process — integrates bulk tanks, day tanks, transfer pumps, secondary containment and HVAC equipment, among others. With this system comes certain regulatory requirements that a facility must adhere to pertaining to secondary containment as outlined by the Environmental Protection Agency or Occupational Safety and Health Administration. If improperly designed, a chemical feed system might not meet specifications, or the facility could fail to meet permitting requirements.

A cost-saving measure, however, can be found in properly sized bulk tanks to streamline (or reduce) the number of chemical deliveries to the site. The fewer deliveries over the course of the year, the better. Also, the location of a chemical feed system in relation to the site is important as delivery trucks need to access outside connections to fill these bulk tanks.

BIM Utilization for Seamless Design-Build Coordination

A key differentiator in an engineer-led design-build team is the integrated utilization of building information modeling (BIM) and associated virtual 3D design tools by all team members. Virtually building a membrane softening facility in a continuous feedback loop with the builders and estimators allows for real-time cost and schedule impacts of associated design changes.

A crucial start to the BIM process in a facility retrofit scenario is performing internal 3D scanning of impacted spaces for a complete and accurate model of the existing facility. This model is then used as the basis for proposed work and interdisciplinary coordination, resulting in optimally sized floor plans, compact support system design and reduced rework.

Accurate modeling and virtual building of planned electrical, mechanical, plumbing, process and chemical systems further streamlines the design and construction process. An added benefit of such modeling is the potential it provides for prefabricated components and support systems, if desired, which can improve schedule, quality and job site safety.

The Outcome of a Well-Balanced, Optimized Design

For efficiency in design and operations, keep these key components in mind when designing and constructing a membrane treatment facility. Part of a successful optimized design also includes interdisciplinary coordination to reduce capital costs, improve navigation around equipment areas and provide flexibility for future expansion. At its core, a well-thought-out design maintains the delicate balance of too much versus too little space to properly plan for necessary equipment and treatment components. When done correctly, the project delivers a highly effective membrane treatment facility as well as short- and long-term cost savings to the owner.


Whether repairing a wastewater tank or building a membrane treatment facility, a design-build approach streamlines the entire project delivery process, reducing schedule and cost and delivering higher-quality results. Efficiency and collaboration, also required when creating an optimized design, drive this execution approach as well.

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Steven Thompson is a Burns & McDonnell project manager with nearly 15 years of experience in the planning, design and construction of municipal infrastructure, including a variety of water and wastewater projects.