Site work and paving for a mixed-use development in Gwinn, Michigan. Completed plans call for site work for a road / highway; and for paving for a road / highway.

Project Description This project consists of rehabilitating the surfaces of parallel Taxiway A and connector Taxiways B, C, and D. This will require the milling (removal) of the top layer of concrete interface (approximately 2-3 inches in depth) on Taxiways A, B, C, and D which will be replaced with approximately 2-3 inches of asphalt. This construction project is planned to begin around June 2024. The reason for this sampling is that PFAS has been found elsewhere on the airfield, primarily associated with the historic use of Aqueous Film Forming Foam (AFFF) from United States Air Force (USAF) firefighting operations when SAW was a military base. Since SAW has been designated as a Part 201 site by the Michigan Department of Environment, Great Lakes, and Energy (EGLE), it has an obligation to exercise "due care" in performing activities to mitigate exposure of PFAS above cleanup criteria to protect public health. As a result, there is a need to sample for PFAS in concrete being excavated as part of the taxiway rehabilitation project. Additional information about the history of PFAS detection at SAW and areas where PFAS has been detected can be found on the Michigan PFAS Action Response Team (MPART) website. Scope of Work As noted, the sampling of PFAS in concrete is limited to the taxiway rehabilitation project area identified in Attachment A. The specification for sampling existing taxiway concrete is included in this Scope of Work. As illustrated in Attachment A, the project area is divided into four (4) Decision Units (DUs) where samples are to be taken within the defined areas of existing concrete pavement. Within each DU, five (5) incremental samples (IS) shall be collected to obtain a total of 1 kilogram (kg) of concrete borings per area. The approximate locations where these samples are to be taken are identified as an "X" in the figures presented in Attachment A. Each sample is to be collected at a 2-inch diameter to a depth of 2 inches. If additional IS samples are required to obtain 1 kg of concrete borings in a DU, the location of the samples distributed evenly throughout the DU is required. Coordination with SAW will be required prior to sampling to determine the order of sampling the four DUs. Concrete Sample Collection Collection of concrete borings will require use of a water-based drilling method, such as a roto-hammer or other designated and approved method. The borings will then be broken to a specification defined by the laboratory for analysis using Environmental Protection Agency's (EPAs) Method 1633 (Attachment B) and a Synthetic Precipitation Leaching Procedure (SPLP). The sampler should plan to break the borings into a powder or very small gravel size at a minimum for analysis. All sampling materials, equipment, field blanks, containers, and equipment decontamination reagents must be PFAS-free. Water used for equipment decontamination must also be free of PFAS analytes. The sampler shall be responsible for testing equipment decontamination water to verify the lack of PFAS. Samples shall be collected using wide-mouth high density polyethylene (HDPE) jars that have been lotcertified to be PFAS-free and fill no more than 3/4 full and type in accordance with Method 1633. Solid samples should be protected from light (in HDPE containers) from the time of collection until receipt at the laboratory