Early planning and leveraging multiple best practices can enhance project outcomes.
Design and implementation of stormwater controls on any construction project can be challenging and complex, often resulting in headaches for the design and construction team. For example, it can be tricky to decide the type and number of stormwater controls that would be the most successful, and cost effective, for meeting the specific requirements of a project.
Proper planning for stormwater management early can alleviate many potential pitfalls. Furthermore, utilizing an integrated approach to stormwater controls that leverage multiple best practices can yield enhanced results and a better end-product.
Engineers and their clients would be wise to consider early in the design process a holistic approach to stormwater management, choosing best management practices (BMPs) that provide multiple benefits. This integrated approach can help engineers better service their clients and offers a variety of advantages. The top four benefits of this integrated stormwater strategy include the following:
Benefit 1: Encourages early planning
All projects are unique, and stormwater solutions should be tailored to a project’s specific location, use, and goals. Increasingly, those needs call for multiple stormwater controls. As stormwater controls multiply, the more time is needed to plan ahead for those controls. Thus, stormwater planning should be considered early and often in the design process. It will save time, money, and heartache later!
For example, Virginia Military Institute (VMI) recently faced a stormwater design challenge when planning the school’s new Corps Physical Training Facility. Nestled among the Blue Ridge Mountains in Lexington, Va., VMI is the oldest state-supported military college in the United States. The proposed state-of-the-art training facility will play an integral part in fulfilling VMI’s mission to prepare citizen-soldiers for a life of service and leadership. Given the site constraints, the design-build team had to get creative with the design of this facility, including the stormwater practices.
Topographic and geologic constraints at VMI create a unique and daunting set of challenges anytime the school needs to add new facilities. VMI is located in an area with steep slopes and karst geology (i.e., sinkholes). An initial site limitation to the training facility was the Town Branch Creek, which runs beneath the building and is prone to flooding. Addressing this issue with stormwater controls accomplished a number of objectives, including no impact to the current flood zone adjacent to the creek at VMI and in the surrounding community. Of course, stormwater planning also had to take into account erosion control phasing during construction to prevent sediment from washing into the creek from the jobsite to minimize environmental impacts to the stream.
Stormwater controls were planned and tailored to the site’s conditions, geology, and ultimate use early in the design process. As many engineers understand, it’s also important to consider controls that are easily maintainable and accessible. In all, this project called for more than a dozen stormwater controls, including a vegetative roof, three bioretention ponds, permeable pavers, an underground cistern to collect runoff, a rainwater harvesting system, an underground stormwater retention facility, and five manufactured BMPs.
By planning ahead early in the design process, engineers, architects, general contractors, and landscape architects can better understand project constraints and opportunities, manage project schedules, and craft an accurate construction budget.
Benefit 2: Generates collaboration
Working with multiple stormwater controls and BMPs requires significant understanding of each control and how it will interact with the others. Collaboration by the entire design-build team is needed to identify possible challenges and opportunities for stormwater solutions. By taking an integrated approach with multiple stormwater solutions, the entire team is likely to collaborate more consistently — because they have to.
With the VMI facility referenced above, that collaboration was crucial to the project’s delivery. When working with numerous stormwater controls, it’s best to take the “more is more” approach with extensive communication, brainstorming sessions, and collaboration to ensure that all possible stormwater management solutions are well-thought out.
One such collaboration resulted in the elevation of the facility above creek level to prevent future flood damage. Flood models, developed with input from the design-build team, helped guide that elevation. Furthermore, as a result of this collaboration, the design team recognized the need to utilize as much space as possible to mitigate flooding events and incorporated the parking structure under the building. Thus, if flooding occurs from a storm event greater than the 100-year storm, the parking structure serves as an overflow route for the facility, thereby not impacting the primary building space.
Proactively insist on cooperation throughout the entire process through the installation of all controls. This ongoing communication pays off in the long run by both delivering more innovative stormwater controls and avoiding added expenses related to incorrectly installed or insufficient controls.
Benefit 3: Helps secure permit approval
As many engineers understand, constant regulatory changes from federal and state authorities can complicate the permit approval process. However, by addressing stormwater issues up front, the approval process can run more smoothly. Taking a multi-layered approach is often the most effective solution when working to secure environmental approvals.
With permit requirements becoming stricter, it’s important to take into account the purpose of all stormwater controls and how they will be managed during initial concept planning.
One important tip to note related to permit approvals is to take a big-picture approach. Whether a public or private project, think beyond the project’s immediate boundaries to options on other lands. The result often provides more watershed benefits and volume controls than at the project site.
For example, if your project is in a remote area, consider installing the required control, such as a bioretention basin, on other land you might control within the same watershed, such as next to a parking lot or public facility. This will likely provide more benefit through greater pollutant removal and volume reduction by addressing the parking lot rather than an undeveloped area. The best part is that this approach can still help you secure the necessary permits for a project to move forward.
Benefit 4: Produces more creativity
Multiple stormwater controls allow for more creativity when responding to site constraints, cost savings, environmental implications, and more. Thinking holistically about how stormwater controls can provide multiple benefits to the project is always a great idea.
With the new training facility at VMI, construction of traditional bioretention was challenging because of the steep slopes on the site. Brainstorming ideas was vital to create a “stepped” bioretention basin design, where water flows into two to four terraces before overflowing through the lower basins and ultimately running into the stream after it has been filtered.
There may be times when site constraints include a limited footprint with which to work. In these instances, consider the interaction between stormwater controls and structural requirements. In the VMI project, site constraints and topography had significant impact on both stormwater solutions and the structural engineering of the facility. For example, the design team had to get creative when calculating and designing grading of the entrances to the parking structure. If the grading was too steep, cars wouldn’t be able to access the parking. Alternatively, the grading had to be just right to meet stormwater specifications regulations.
Creative solutions also can deliver cost savings. Consider creating a rainwater harvesting control where water is collected for use within the building. While the control helps filter water runoff, it also saves on utility bills by recycling the rainwater into the building’s cooling and grey water system.
Finally, creative stormwater controls often serve multiple purposes. For example, use permeable pavers in sidewalk areas to provide an aesthetically pleasing surface while helping to meet stormwater needs. These creative solutions add value to a project beyond controlling runoff.
Not every project will require a dozen stormwater solutions. However, projects increasingly need to leverage multiple stormwater controls. Taking an integrated approach to stormwater management offers many benefits and delivers successful results. Prioritizing stormwater controls and collaborating early in the process can help better service clients and the overall community.
Carolyn Howard, P.E., is vice president and regional manager for site development and infrastructure in the Blacksburg, Va., office of Draper Aden Associates (www.daa.com), an engineering, surveying, and environmental services firm that serves the Mid-Atlantic. She works closely with other engineers, private institutions and organizations, and public agencies on stormwater controls and best practices. She can be reached at email@example.com.