Assessing the Feasibility of Green Stormwater Infrastructure Implementation in Downtown Durham

Abstract

EXECUTIVE SUMMARY

BACKGROUND

The city and county of Durham are currently determining how to comply with two sets of nutrient management strategies which mandate significant water quality improvements for Jordan and Falls Lakes. These strategies, known as the Jordan and Falls Lake Rules, seek to reduce the quantities of phosphorus and nitrogen in the lakes’ waters. Preliminary estimates by Durham Stormwater Services on the costs of addressing these regulations range between $1.17 and $1.33 billion over the next twenty years. The fiscal demands of these rules threaten the continued efforts to revitalize Durham, as they may compel the city to redirect hundreds of millions of dollars in local revenue to achieve compliance with the rules. This could threaten the economic progress of downtown Durham by siphoning away resources which could be devoted to economic development or for essential services to the city’s poorer residents.

Emerging trends in stormwater management may offer a solution to this dilemma. The burgeoning movement of green stormwater infrastructure uses engineered methods to mimic natural systems of water absorption and filtration. Green stormwater infrastructure (GSI) uses methods that either collect and use the stormwater where it falls; slow the flow of stormwater before releasing it into traditional, “gray” infrastructure; or infiltrate the water on the spot, filtering out unwanted nutrients and directing the water into groundwater sources rather than funneling it through man-made channels.

POLICY QUESTIONS

The policy questions for this masters project center around the applicability of green stormwater infrastructure to the situation in which Durham finds itself, with a focus on how this plan would interact with the economic development of downtown Durham. Therefore:

• Can a green stormwater infrastructure plan in downtown Durham address Durham’s needs for stormwater nutrient reduction in a way that encourages continued economic development? • What might such a stormwater plan look like in terms of the stakeholders involved, viable infrastructure to install, and means to finance or incentivize its implementation?

DETAILS OF PROBLEM

Though the successful promotion of GSI in other cities has highlighted the benefits of this new stormwater framework, there are certain elements of Durham’s situation which make its applicability problematic. The issues fall under five categories:

1) The details of the two lakes’ rules: Because Durham’s stormwater system is constructed differently than the systems of other cities incorporating GSI, and because the lake rules target different water quality standards, GSI implementation strategies from other municipalities cannot be readily transferred to Durham. 2) The characteristics of Durham’s soils: The GSI options which would best address the lake rules’ requirements are those which would infiltrate stormwater on-site and direct it to groundwater sources. However, Durham’s dense soils make the implementation of those GSI options problematic at best. 3) The characteristics of Durham’s climate: Durham’s rain levels and temperatures could lead to mixed performance for some of the most common GSI options. 4) The nature of downtown Durham’s building stock: The density of buildings in downtown Durham limits the available GSI options and complicates the necessary processes for successful design and implementation. 5) The funding available for GSI implementation: Federal and state funding which Durham could normally target to incentivize GSI implementation is being cut at both levels of government.

SUGGESTED ALTERNATIVES

The following options will provide more information to policymakers on whether and how GSI could successfully be applied to the regulatory requirements facing Durham.

1) Produce a district-level or building-level audit of downtown Durham and target the appropriate GSI investments to specific districts or building types. 2) Increase local stormwater management fees and provide adequate credits for GSI implementation to incentivize owners to adopt GSI options. 3) Adopt mandates to require the inclusion of GSI in the construction or refurbishment of public buildings. 4) Develop a new Durham city oversight committee which coordinates the efforts of the water management, transportation, economic development, and planning departments to address cross-jurisdictional issues and ensure alignment of priorities. 5) Construct a public/private partnership with local developers to provide public seed investments to stimulate private spending on GSI. 6) Incorporate funding for GSI within the creation of a downtown business improvement district (BID). 7) Continue lobbying efforts with the state to approve the use more GSI options and to provide more credit for the options that encourage innovative stormwater management. 8) Continue data collection regarding nutrient loading and GSI performance to provide better targeting of GSI options. 9) Review and update Durham codes that may unknowingly be discouraging or blocking the implementation of GSI.