Stacy Hettmansperger

Stacy Hettmansperger

Stacy Hettmansperger

Speaker | City of Phoenix

Phoenix, AZ | 602-495-5600 | stacy.hettmansperger@phoenix.gov

USCC Member

Stacy Hettmansperger serves as the Operations Manager for the City of Phoenix Public Works Department. In that role she oversees the transfer station, recycling facility, compost facility and palm frond diversion operations at the City’s Resource Innovation Campus. Stacy has worked for the City of Phoenix for seven years, six of which have been in the Public Works Department. Stacy holds a Master’s Arts Degree in Public Administration from Arizona State University with a concentration in Urban Management. Stacy also has a Bachelor’s of Arts Degree from Arizona State University in Political Science. Stacy was awarded 2017 Operations Manager of the Year by the Arizona Chapter of Solid Waste Association of North America.

Presentation One: “How the City of Phoenix Leveraged Public Private Partnerships to Develop an Organics Diversion Program”

co-authors: Jeff LeBlanc / Jeff Gage

Session: “Public-Private Partnerships Pave the Path to Prosperity”

Time: Tuesday, January 29, 4:45 PM – 6:15 PM

Presentation Summary: In 2013, Phoenix Mayor and City Council members announced Reimagine Phoenix, a citywide sustainability initiative to divert 40 percent of residential waste from the city landfill by 2020. This initiative focuses on development of public and private partnerships, offering new solid waste services and increasing education and community outreach centered around transforming trash into resources. In Fiscal Year 2014-2015, the City partnered with Cascadia to conducta waste characterization study that identified nearly 2/3 (65.3%) of residential solid waste consists of material that can be diverted from the landfill through recycling or composting programs. The results of the waste characterization study identified organics as a significant opportunity to assist the City in achieving its diversion goal, and led the City to closely evaluate the feasibility of developing organics diversion programs and constructing a compost facility.

The City implemented Phase Iof its residential curbside green organics program and implemented a discounted gate rate program for landscapers delivering clean green to the transfer stations. In January 2015, the City began a food scraps pilot compost area at the 27th Avenue Transfer Station to divert food scraps collected at City sponsored special events beginning with Super Bowl XLIX. Through October 2017, the pilot compost area supported diversion of food scraps from other City sponsored zero waste events, Sky Harbor Airport, Phoenix Convention Center and private haulers.It also allowed City staff the opportunity to learn a negative aeration composting process until the City completed construction of itsnew compost facility, located at the City’s Resource Innovation Campus.

Through the City’s design and construction partnerships with local firms including Arrington Watkins Architects, Brycon Construction and Green Mountain Technologies, the 27thAvenue Compost Facility was designed with a Turned Aerated Pile Technology with an aerated pad and computer controlled reversing positive/negative aeration. The team also designed the facility to capture all of the process and stormwater onsite to be reused in the first five zones of the mass bed. This was one of the sustainability features that led the facility to be the first solid waste infrastructure project in the United States and the first project in Arizona to earn Envision recognition from the Institute for Sustainable Infrastructure. The Envision system rates sustainable infrastructure across the full range of environmental, social and economic impacts.

The City partnered with WeCare Denali to operate the compost facility, and market and sell the finished compost produced at the facility. The 27thAvenue Compost Facility construction completed in April 2017 with the capacity to process up to 55,000 tons of inbound organics per year initially with an option to scale itup to 220,000 tons per year in the future with additional construction. WeCare Denali began commissioning the facility in June 2017 and began marketing and selling the finished compost produced from the facility in Fall 2017.


Presentation Two: “Circular Economy in Action: Compost Turf Study with City of Phoenix and Arizona State University”

co-authors: Larry Polk / Bill Campbell

Session: “Compost Uses and Markets: Critical Info for Customers”

Time: Wednesday, January 30, 8:45 AM – 10:15 AM

Presentation Summary: In January 2015, the City of Phoenix Public Works Department established a pilot compost area at the 27thAvenue Transfer Station to divert food scraps collected at City sponsored special events beginning with Super Bowl XLIX and food scraps from sources including Sky Harbor Airport and Phoenix Convention Center. The feedstock also included landscape and parks clippings. In the Summer of 2015, the Public Works Department launched the Parks Turf Compost Study in partnership with the Parks and Recreation Department and the Resource Innovation and Solutions Network which is a program of the Walton Sustainability Solutions Initiatives at Arizona State University (ASU). The objective of the three-year study was to identify the operational, environmental and economic impact of managing multi-purpose turf at city parks using compost compared to traditional parks turf management practices using chemical fertilizer.

Nine City parks were selected based on their use, type of soil, and irrigation method. During the first year, Parks and Recreation developed a process to ensure consistency with each application. During the Fall and Spring compost applications, Public Works produced and delivered the compost from the pilot compost area and ASU conducted the soil sampling and analysis for all of the plots.

The results of this Parks Turf study indicate that compost has a positive effect on the soil,increasing the levels of many macro and micro nutrients at a rate higher than or equivalent to that of fertilizer resulting in a healthier soil profile at the city parks.

Year 1 of this study laid the groundwork to operationalize the compost application process and created a baseline to compare the study plots with the control plots. In Year 2, a model was developed to analyze the costs and benefits of managing the parks turf using compost and determined that the compost process is significantly more costly than fertilizer applications.

Year 3 further evaluated these costs and identified that if the use of compost resulted in a reduction of watering requirements by 18% or higher, the cost saving for the reduced irrigation could cover the additional cost of managing park turf using compost.

Beginning in July 2018, WSSI and the City of Phoenix will expand this study to evaluate the water savings potential of compost applications in city parks. The strategy to quantify the water savings potential of compost treatments is based on three methods:
1) Observations of the treatment effect on soil water and evapotranspiration.
2) Soil water balance modeling in the various treatments and parks.
3) Development of water conservation scenarios using the calibrated model.

This strategy will provide evidence of the capacity of compost treatments to retain soil water and minimize evaporative losses. In addition, a modeling tool will be used to test the impact of alternative compost treatments and/or irrigation scheduling methods.