Transformation of a 84-Acre Former Railyard and Brownfield into Bonnet Springs Park, Lakeland, Florida
Todd Kafka, P.G., Senior Principal Hydrogeologist, Geosyntec Consultants, Inc.
Located within one mile of downtown Lakeland, the former Lakeland railyard property has long been identified as an ideal redevelopment target to support the growing downtown area, if only it had not operated as a railyard for nearly 50 years! However, with the significant support of private financing and unwavering perservance of local developers and stakeholders, Bonnet Springs Park (BSP) is blooming into a public park ready for visitors in 2023. Geosyntec joined a team of local engineering, consulting, and legal firms led by Sasaki, Inc., a world-renowned landscape architectural firm based in Boston, to transform the 84-acre railyard into the upland portion of the 145-acre footprint of BSP. Geosyntec had previously worked at the former railyard for the rail owner and had obtained a conditional site rehabilitation completion order (C-SRCO) for soil and groundwater using risk management option (RMO) III and deed restrictions that prohibited groundwater consumptive use and residential land use due to elevated arsenic concentrations in soil. The sale of the railyard to BSP was contingent upon FDEP’s approval of a Brownfield Site Rehabilitation Agreement (BSRA), which was obtained by Goldstein Environmental Law. Geosyntec developed a conceptual approach to convert the land-use from industrial/commercial to recreational, which would require soil remediation to achieve an alternative soil cleanup target level (A-SCTL) of 5.5 milligrams per kilogram (mg/kg) for arsenic. The foundation of our approach was eliminating offsite disposal of impacted soil by (i) moving and consolidating surplus soil from grading into two mounds onsite, (ii) identifying and delineating arsenic-contaminated soil at the new subgrade elevation across the former yard footprint for removal/consolidation into the two mounds to achieve the recreational A-SCTL, and (iii) capping the two mounds with 2 feet of clean fill to serve as engineering controls. Sasaki designed the entire park based on this conceptual soil remediation approach. In order to comply with Chapter 62-780 requirements for using 95% upper confidence limits (UCL) to assess soil exposure, Geosyntec divided the future park areas overyling the former railyard into exposure units (EU) based on the potential exposure a visitor in each area of the park (e.g., trails, parking areas, gardens buildings, boardwalks, etc.) may experience relative to residual arsenic concentrations in soil; BSP also required that one EU (children’s play area) achieve the residential SCTL as a conservative measure. Geosyntec used projected grading plans to begin extensive soil assessment to identify soil removal areas in each EU. Arsenic “hotspots” were evaluated and selectively removed from the dataset in each EU until the 95% UCL was attained. Excavation boundaries were established with step out samples and XRF screening to develop soil removal plans for each EU. During this process, Geosyntec coordinated multiple meetings with FDEP and submitted several deliverables to keep FDEP informed of progress and findings. Ultimately, over 250,000 cubic yards (cy) of arsenic-impacted soil was consolidated in the two mounds, which were capped with over 75,000 cy of properly-characterized fill from three separate sources. Geosyntec obtained a provisional C-SCRO (pending final stormwater design) from FDEP in March 2020, thereby allowing the project team to move forward with abovegrade construction.
Todd Kafka is a senior principal hydrogeologist with Geosyntec Consultants and manages the firm's Tampa office. Todd's 26 years of site assessment and remediation experience has enabled him to build a practice focused on innovative site assessment tools and techniques, bedrock aquifer characterization, fate and transport assessment, and brownfield redevelopment. Todd earned a MS in Geology from Washington State University in 1995 and a BA in Geology/Environmental Science from Middlebury College in Vermont in 1992.