Contractors Road Heavy Equipment Area (Swmu 055) 2023 Annual Groundwater Monitoring Report

This document presents a summary of activities completed in December 2023 to monitor and assess chlorinated volatile organic compound (CVOC) affected groundwater at the Contractors Road Heavy Equipment (CRHE) area, located at John F. Kennedy Space Center (KSC), Florida. The activities summarized include annual groundwater monitoring activities for Hot Spot 1 (HS1), Hot Spot 2 (HS2), the northern area, and the downgradient area; and sub-slab soil gas (SSSG) sampling to investigate potential vapor intrusion (VI).

This facility was designated Solid Waste Management Unit (SWMU) Number 055 (SWMU 055) under KSC’s Resource Conservation and Recovery Act (RCRA) Corrective Action program. HydroGeoLogic, Inc. prepared this report for the National Aeronautics and Space Administration under contract number 80KSC019F0096.

The annual sampling of 15 monitoring wells was conducted in December 2023 for volatile organic compounds (VOCs) and four wells for 1,4-dioxane. Seven monitoring wells also were sampled in December 2023 for underground injection control (UIC) parameters (sodium, total dissolved solids [TDS], and total recoverable petroleum hydrocarbons [TRPH]).
In addition to sampling activities, groundwater levels were collected from 47 of 52 wells to evaluate the shallow, intermediate, and deep groundwater flow.

Tetrachloroethene and trichloroethene were not detected in the 2023 groundwater samples. Cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC) were the only volatile organic compounds detected above Florida groundwater cleanup target levels (GCTLs). VC and cDCE concentrations generally decreased across the site in comparison to prior results but there are still areas where the results for those compounds were above natural attenuation default concentrations (NADC). UIC monitoring indicated TRPH remains above the GCTL in one well and TDS exceeds the GCTL in 5 of the 6 wells sampled. Three of the four wells (MW0025, MW0035, and MW0039) sampled for 1,4-dioxane exceeded the GCTL of 3.2 μg/L. The concentrations ranged from 4.6 μg/L (MW0025) to 6.7 μg/L (MW0035). Statistical analysis indicates that 1,4-dioxane concentrations are decreasing in MW0025 in HS1 and increasing downgradient in MW0035.

A wastewater treatment plant formerly was located on the northeast side of the CRHE Area. As a follow up to the detections of PFAS above screening levels in that vicinity during the centerwide PFAS investigation (AECOM, 2022), groundwater samples were collected from 10 monitoring wells in December 2023 (IW0001S, IW0002S, IW0004I, IW0009S, IW0013S, IW0017I, IW0019I, MW0024, MW0025, and MW0030). Four of the 10 wells reported provisional GCTL exceedances for the sum of concentrations of perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS).

SSSG sampling results indicate that CVOCs in groundwater under the Heavy Equipment Office Building, along with degradation of the groundwater plume through previous IM activities, are not creating sub-slab vapors that may pose an unacceptable risk to the building occupants.