Panther Island is a master planned urban waterfront community north of downtown Fort Worth, Texas. The 320-acre redevelopment area is part of the larger Trinity River Vision project that provides for environmental cleanup, flood protection and infrastructure improvements for neighborhoods adjacent to the West Fork of the Trinity River. The planned public improvements within Panther Island will nearly double the size of downtown Fort Worth and is expected to generate more than $600 million in economic development activity by 2025. The redevelopment project features the creation of a new 33-acre lake that will be connected to a network of canals. The lake and canal network will provide connected public open space that will serve as a key amenity for the estimated three million square feet of commercial space and ten thousand mixed-income residences.

Verdunity was contracted to evaluate three levels of green infrastructure implementation strategies for their effectiveness in protecting that water quality of the lake and canal network. The levels studied included implementations within just the street right of way, expanding into the open space areas and view corridors, and finally expanding to the individual site development parcels. The initial study determined that a large majority of the water quality treatment initiatives could be achieved by implementation of green infrastructure strategies within the street right of way and open space areas. This level of implementation also reduces the area required for storm water management on individual sites, thus allowing for denser development that functions better with the integrated open space network.

A balance of green infrastructure on the surface to treat storm water runoff and grey infrastructure to convey additional flows is necessary to improve and protect the quality of our lakes and streams. A common roadblock to expanded use of green infrastructure is the misconception of higher construction and maintenance costs. Understanding that there are other advantages of expanded implementation of green infrastructure strategies related to quality of life, potential to attract new business, tourism, and new residents, Verdunity set out to quantify the expected benefits for the Panther Island implementation strategies by performing a business case evaluation of each level of green infrastructure implementation.

The evaluations utilized the AutoCase™ for Water Projects software that is being developed by Impact Infrastructure, LLC. The economic model provides a risk-based life cycle analysis and comparison of traditional storm water management utilizing grey infrastructure and multiple levels of green infrastructure implementation. The business case evaluations provided comprehensive economic data that detailed the potential financial gains associated with higher levels of green infrastructure implementation within the Panther Island development.

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The economic models compared construction, operations and maintenance costs of traditional grey infrastructure development to both the right of way and open space green infrastructure implementation strategies. The net present value of costs associated with the most expansive open space strategy exceeded that of traditional development by $1.7 million. The AutoCase™ for Water Projects tool provided the key data to move beyond the common roadblock of higher up front and O&M costs by evaluating green infrastructure’s positive impacts on sales tax and property tax revenues for the development. The model also calculated the net present values of more subjective criteria including willingness to pay for improved water quality and the financial benefits of carbon sequestration and improved air quality. Based on projected commercial and residential development for Panther Island the results of the analysis indicated a net present value benefit of $3.5 million for the right of way implementation strategy and $5.4 million for the open space implementation strategy as compared to the projected benefits for traditional development relying completely on grey infrastructure systems and traditional landscaping. Utilizing these robust economic tools the project team was well equipped to present the overall life-cycle benefits of incorporating green infrastructure into development strategies to the Trinity River Vision Authority. The financial benefits coupled with the benefits of maintaining the water quality of the lake and canals planned for Panther Island make a clear case for expanding the use of green infrastructure in North Texas that will benefit the development community and the community at large.

Mikel Wilkins, PE, ENV-SP, is an Environmental Engineer & Stormwater Management Specialist for VERDUNITY.
Kevin Shepherd, PE, ENV-SP, is a Principle at VERDUNITY. Kevin brings a unique combination of engineering and planning perspectives, along with expertise in business and municipal finance.