[미국] 녹색인프라, 수정 전략 하에 DC의 CSOs 감소 도와
미국 환경보호청(EPA)과 콜롬비아 지구(District of Columbia), DC Water가 CSOs를 2005년 연방동의명령(consent decree)을 줄이기 위한 장기 전략으로 녹색 인프라를 시행하는 데 대한 수정 합의문을 발표했다.
이번 수정으로 DC Water는 Rock Creek 및 Potomac 유역 지역의 CSOs로 인한 수질 문제를 처리하기 위한 녹색·회색 통합 인프라 접근을 추구하게 된다. 이러한 통합적 접근은 합류식 하수관거 유량을 줄이기 위한 설계 방법 및 녹색 인프라를 최적화할 것으로 기대된다.
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Green infrastructure to help DC reduce sewer overflows under revised strategy
Today, the Environmental Protection Agency (EPA), District of Columbia (District) and DC Water announced an agreement to modify a 2005 federal consent decree (CD), allowing DC Water to incorporate green infrastructure in its long-term strategy for curtailing combined sewer overflows (CSOs).
The modification, recently filed in Federal District Court, allows DC Water to pursue an integrated green/gray infrastructure approach to address water quality issues in the Rock Creek and Potomac watersheds resulting from CSOs. This integrated approach utilizes green infrastructure in a targeted and sound engineering manner to reduce these overflows. Green infrastructure uses vegetation, soils and natural processes that mimic nature to store rainwater water where it falls to control wet-weather pollution and create healthier urban environments.
The green infrastructure projects in Rock Creek and Potomac watersheds are slated to begin in 2015 and 2016 respectively, providing more immediate pollution reductions, enhancements to community livability, and green jobs opportunities. Specifically, the CD modification includes:
Potentially eliminating the Rock Creek storage tunnel and significantly decreasing the size of the Potomac tunnel, depending upon the success demonstrated by green infrastructure.
·The District providing the public space necessary for DC Water to construct the proposed green infrastructure projects and making changes to District regulations, codes, standards, guidelines, and policies needed for implementation.
·Requiring the District and DC Water to work together to coordinate capital projects and expenditures for implementing green infrastructure, enabling the efficient use of resources and minimizing costs to ratepayers and taxpayers.
As part of the agreement, DC Water will have an additional five years to complete implementation in the Potomac and Rock Creek watersheds beyond those provided for in the original 2005 CD, which established a compliance schedule to construct tunnels in the Anacostia, Potomac and Rock Creek watersheds. The schedule for completing the Anacostia tunnel remains unchanged.
Under this CD, DC Water will continue moving forward on the construction of the overall CSO control project, known as the Clean Rivers Program. This project involves completion of control structures and tunnels for the Anacostia watershed, which contributes more than 65 percent of the sewage discharged to District waters annually. Major portions of this tunnel system are scheduled for completed and in operation in 2018. When the complex is fully completed in 2025, it will nearly eliminate CSOs to the Anacostia in an average rainfall year.
In November 2011, DC Water proposed to incorporate green infrastructure into its overflow control strategies for the Potomac and Rock Creek watersheds. As part of the request, DC Water submitted analysis demonstrating that modified CSO controls in the Potomac and green infrastructure in Rock Creek could provide equivalent pollution reductions to those in the original plan and were economically feasible. In early 2014, after conducting a public participation process, DC Water also filed a request to EPA to modify the plan for CSO controls and deadlines set forth in the 2005 CD.
[출처 = Water World / 2015년 5월 20일]