How can you optimize the cost-effectiveness of highway stormwater management?

2 Minimize impervious surfaces

One of the main goals of highway stormwater management is to reduce the amount and speed of runoff from impervious surfaces, such as pavement, concrete, and asphalt. Impervious surfaces increase the volume and peak flow of stormwater, which can overwhelm the drainage system and cause flooding and erosion. To minimize impervious surfaces, you can use permeable or porous materials, such as gravel, pavers, or turf, for some parts of your highway design, such as shoulders, medians, or parking areas. You can also reduce the width or length of your pavement, or use alternative alignment or grading options, to limit the amount of impervious surface area.

3 Implement low-impact development

Low-impact development (LID) is a design approach that mimics the natural hydrologic cycle and aims to infiltrate, store, filter, and evaporate stormwater at or near its source. LID techniques include bioretention, rain gardens, vegetated swales, green roofs, rain barrels, and permeable pavements. LID can improve the water quality and quantity of stormwater runoff, as well as enhance the aesthetic and ecological value of your highway design. LID can also reduce the construction and maintenance costs of your stormwater management system, as it uses less materials, energy, and land than conventional drainage methods.

5 Integrate with other highway elements

Your stormwater management system should not be designed in isolation, but rather integrated with other highway elements, such as the pavement, the subgrade, the landscaping, the lighting, and the signage. By integrating your stormwater management system with other highway elements, you can create a more functional, efficient, and harmonious design that meets the multiple objectives and requirements of your project. For example, you can use the pavement as a conveyance or storage element, the subgrade as a filtration or infiltration element, the landscaping as a treatment or retention element, the lighting as a monitoring or warning element, and the signage as an educational or regulatory element.

6 Evaluate the life-cycle costs and benefits

Finally, to optimize the cost-effectiveness of your stormwater management system, you need to evaluate the life-cycle costs and benefits of your design alternatives. The life-cycle costs include the initial capital costs, the operation and maintenance costs, and the replacement and disposal costs of your stormwater management system over its expected lifespan. The life-cycle benefits include the environmental, social, and economic benefits of your stormwater management system, such as the reduced flood damage, the improved water quality, the enhanced habitat, the increased property value, and the lower greenhouse gas emissions. By comparing the life-cycle costs and benefits of your design alternatives, you can select the most cost-effective stormwater management solution for your highway project.

7 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?