Challenge Met with Success: West Park Equalization Facility Achieves Platinum
- Evan Bowles - Hazen and Sawyer
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 engineer was tasked with designing a tank providing additional storage at the existing storage tank and pump station site located adjacent to West Park. West Park is comprised of baseball fields, soccer fields, basketball court, a small playground and a small picnic pavilion. The existing park 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.
Because of the unique integration of infrastructure, significant park improvements, commitment to recycling/reuse and innovative material use, the project team determined that the project could potentially receive a high level of recognition under the Envision Rating system. An Envision pre-assessment, conducted during the 60% design phase, suggested that the Gold recognition level was likely achievable, with a Platinum level of recognition achievable. This reinforced that the project team had designed the project properly, and the assessment provided a gap analysis that identified ways to improve the sustainability of the project. The project was ultimately awarded a Platinum award in early 2016, citing the high marks achieved within many of the pursued credits.
The presentation will provide an overview of the project, as well as credits that created challenges for the award, and opportunities for the design. Examples include:
• Credit RA1.5: The project team originally understood the credit to include waste generated during construction. Given the planned level of material salvage and recycling, the level of achievement was estimated at 100%. However, after the first round of Verification, the project team learned that the credit only considers diversion of waste generated during long-term operation of the project/facility. To achieve this, the project team specified that the project did not include a concession stand (as originally planned) to reduce waste generated by its operation, and added recycling containers to the facility grounds.
• Credits NW2.1, NW3.1, NW3.4, and CR1.1: At current design at the 60% phase, the project team was not able to achieve high levels of achievement in the noted credits. To receive higher marks in these credits, the project team added a significant amount of trees (204% increase over original design). Tree species included River Birch, Eastern Redbud, White Fringetree, Swamp White Oak, Red Oak, and American Elm. These additional plantings positively impacted the final design of the facility.
• Credit RA3.1: The project team’s original assessment indicated that a water balance exercise resulted in no net impact to local freshwater availability. ISI’s verifier disagreed, stating that the irrigation water withdrawn was ultimately sourced into the receiving waters adjacent to the site. The project team reassessed the water balance considering the adjacent receiving streams contribution to the larger Cumberland River (potable water source), and the outcome reflected a net positive addition of fresh water to the watershed since infiltration trench, detention features, and pervious surfaces were included in the design.
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