From Nashville to New York City: Practical Applications of the Envision Rating System
- Saya A. Qualls, Evan C. Bowles, Norman Bradley - Hazen and Sawyer
The 21st century presents engineers, utility managers and operators with challenges unlike any others faced by our predecessors – crumbling infrastructure, increasing demand for services, diminishing resources and undeniable impacts of climate change. The American Society of Civil Engineers (ASCE) 2013 Report Card for America’s Infrastructure graded both drinking water and wastewater infrastructure at the D level.
ASCE identified leadership, sustainability, resilience and funding as keys to addressing the nation’s significant infrastructure needs.
Current design, construction and operational practices of our infrastructure systems can have negative impacts by over-consuming resources and damaging ecosystems. Efficiently-operating infrastructure is an essential component for a prosperous and growing economy. Dependable water and wastewater systems protect public health and water resources.
The Envision™ Sustainable Infrastructure Rating System is a project assessment and guidance tool for sustainable civil infrastructure design. It was developed by the Institute for Sustainable Infrastructure (ISI) and the Zofnass Program at the Harvard Graduate School of Design.
ASCE, the American Council of Engineering Companies (ACEC) and the American Public Works Association (APWA) identified the need for a standardized sustainability framework for civil infrastructure projects. They formed ISI to develop and administer the Envision rating system.
The system consists of 60 credits in 5 categories:
Quality of Life – positive community impact
Leadership – commitment of project owners, designers, builders and operators
Resource Allocation – the project’s use of renewable and non-renewable resources
Natural World – the project’s effect on ecosystem functions
Climate and Risk – the project’s contribution and resiliency to short/ long-term risks
There are 4 award recognition levels:
Bronze: > 20 % of applicable points
Silver: > 30 % of applicable points
Gold: > 40 % of applicable points
Platinum : > 50 % of applicable points
More than just rating and recognizing projects, the goal of Envision is to help designers identify ways in which sustainable approaches can be used to plan, design, construct and operate infrastructure projects. It provides opportunities for improved technical performance in parallel with social, environmental and economic improvements.
The projects presented in this work demonstrate how the system can be used to recognize achievement in sustainable design and to provide a more holistic approach to analyzing project alternatives at varying phases of project development and design.
Nashville’s West Park Equalization Facility, Phase II and Park Improvements is a joint project between Metro Nashville’s Water Services (MWS) and Parks and Recreation (MPR). MWS is under a consent decree to eliminate unpermitted discharges of sewage from its collection system primarily during wet weather. Part of Nashville’s plan is to increase in-system storage and then release stored sewage to the wastewater treatment plant when system flows decrease. The original project purpose was to provide additional storage at the existing storage tank and pump station site located adjacent to West Park. However, the proposed tank site was located in the floodway of Richland Creek. MWS considered two off-site locations that would have required the construction of multiple tanks, a significant increase in piping and an overall increase in project cost. Another alternative was to locate the tank in the adjacent park which would eliminate the increased piping and could accommodate a single tank. West Park is comprised of baseball fields, soccer fields, basketball court, a small playground and a small picnic pavilion. The existing facilities are in need of repair, are not fully utilized and do not meet the needs of the surrounding community. MWS proposed locating the tank within the existing park; using the cost savings to fund much needed park improvements. The project then became a collaboration between the two departments – which in addition to providing park improvements and wet weather storage of wastewater will create new public space and connectivity to the city-wide greenway with the construction of a walking trail around the existing tank site.
The Envision pre-assessment was conducted during the 60% design phase and the verification process was initiated after the 90% submittal. Because of the significant park improvements, commitment to recycling/reuse and innovative material use, the project, the first in Tennessee, is expected to receive a Platinum rating. Application of Envision at this point also served to identify other measures that could be added for a more sustainable design.
The New York City Department of Environmental Protection (NYCDEP) Rockaway WWTP is the city’s smallest, most underloaded, least energy efficient, and most vulnerable WWTP. Hurricane Sandy caused extensive damage to Rockaway peninsula and recent studies indicate that climate change will remain a perpetual risk for the plant. Three alternatives were identified for consideration:
1 – Maintain Rockaway WWTP
2 – Consolidate to 26th Ward WWTP via horizontal directional drill
3 – Consolidate to 26th Ward WWTP via bored tunnel under Jamaica Bay
The Envision rating system was used to assess the inherent sustainability of each alternatives. All three alternatives were holistically evaluated and ranked comparatively within fifty-five Envision credits to identify the greatest sustainable impacts over their full lifecycle.
Alternative 3 scored significantly higher because it allows for closure and revitalization of the Rockaway WWTP site, less community disruption during construction and O&M of conveyance system and highest reduction of energy usage and greenhouse gas production.
Decommissioning a 45 mgd plant and construction of a tunnel underneath a National Park would be unprecedented domestically. NYCDEP will carefully consider the economic analysis and sustainability/resiliency performance as provided by the Envision screening, to inform the ultimate decision. Application of Envision within the conceptual planning stage permitted a more objective comparative metric for all three possible scenarios. Also, use of this rating system early in the planning process will insure that the highest potential sustainable implements are available and applied to the selected project.
For more information, please contact the author at email@example.com.
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