Determining implementation barriers for green infrastructure for coastal flood control

Objectives

1. To estimate changes in potential floodwater volumes based on different stormwater control structures imposed by city ordinances. The deliverable from this objective will be a stormwater modeling report for each site.
2. To estimate construction and long-term operation costs for stormwater infrastructure, including green stormwater infrastructure (GSI), based on different versions of city ordinances. The deliverable from this objective will be a life-cycle cost assessment (LCCA) report for each site.
3. To determine at what point the city ordinances or regulatory requirements for GSI increase life-cycle costs to the point that it is not practical to build. The deliverable from this objective will be a Financial Internal Rate of Return (FIRR) spreadsheet tool for each site.
4. To modify ordinances to include flexible GSI options for coastal communities to improve their resilience to climate change and their Community Rating System (CRS) scores without imposing expensive building costs that might have the effect of limiting GSI implementation. The deliverable from this objective will be model stormwater and flood management ordinances for each partner city.

Methodology

This interdisciplinary team of engineers and attorneys will test whether economic and regulatory barriers block implementation of green infrastructure by evaluating coastal city ordinances, rainfall-runoff computer models, and life-cycle costs on stormwater control infrastructure. To assess the effectiveness of green stormwater infrastructure (GSI) in preventing excessive rainfall from flooding properties, the team will examine the plats and design drawings of two properties. This information will be used to create stormwater runoff computer simulations according to different GSI scenarios. The life-cycle cost analysis (LCCA) will also use computer software. All software used in this study consists of widely used and respected tools in the engineering community.

To estimate construction and long-term operation costs, the engineering team will assess life-cycle costs for green infrastructure practices to estimate the overall cost of different alternatives. Both the modeling and the LCCA will help select the types of green infrastructure that ensure the lowest overall cost and highest stormwater runoff reduction. This economic analysis will help determine a financial internal return on investment (FIRR) for flood mitigation using green infrastructure.

The engineering team will coordinate with the legal team to ensure that any existing regulatory GSI of each community is evaluated. As part of this analysis, the legal team, both attorneys and law students, will generate preliminary information on ordinances based on city building codes and related expenses of construction. The legal team will analyze city ordinances from Biloxi and Orange Beach to see how the ordinances influence the application of green infrastructure. Additionally, the legal team will talk with city officials to learn of perceived obstacles to GSI development and policy goals for future regulations. Law students will assist, affording an expanded learning opportunity beyond the classroom. The ordinance analysis will examine variations of requirements of green infrastructure that result in different stormwater flows.

Rationale

This interdisciplinary applied research will assess several aspects of GSI implementation, including evaluating the effectiveness of GSI techniques to prevent flooding, conducting life-cycle cost assessments of GSI implementation, and analyzing whether city ordinances pose a legal or economic barrier to implementing GSI in communities of the Northern Gulf of Mexico. The research will use the coastal cities of Biloxi, Mississippi, and Orange Beach, Alabama, as the testing ground, examining the regulations of each city and using a site from each city to analyze the economics and effectiveness of GSI implementation. This research will address goals under the Mississippi-Alabama Sea Grant Consortium’s resilient communities and economies focus area for 2018-2021 (MASGC 2018), specifically “Utilize comprehensive planning and adaptive management strategies to enhance community resilience and adapt to hazards and changing environmental and socioeconomic conditions.”

This study is unique for several reasons. For example, past research on GSI tends to focus on computer modeling of GSI effectiveness on watershed and city-wide scales of entire floodplains. More typically, smaller communities consider employing GSI on a site-by-site basis, and those sites are small. This proposal is scaled to evaluate smaller sites. Thus, this project will contribute valuable data to GSI economics – project-by-project implementation in otherwise smaller urban areas.

Also, the proposed project stands out by focusing on the GSI costs for communities along the Northern Gulf of Mexico, an understudied area. The economic and environmental consequences associated with climate change are different for these Northern Gulf communities than for areas of existing studies. Both Biloxi, Mississippi, and Orange Beach, Alabama, average 65 inches of rain a year. The study will develop data useful to other similarly situated communities along the Gulf.