DFW Beach Site, Lot No. 163 E 01 - Lower Base, Saipan, CNMI
The Commonwealth of the Northern Marianas Islands (CNMI), Bureau of Environmental and Coastal Quality (BECQ) retained Koa Consulting (Koa) to conduct a Phase II Environmental Site Assessment (ESA) for Lot No. 163 E01 or the ‘DFW Beach Site’, located in Lower Base, Saipan. This Phase II ESA followed the recommendations of a Phase I ESA (Koa 2022) which assessed and evaluated the potential for petroleum contamination uncovered during excavation activities in 2019.
The purpose of this Phase II ESA was to assess the nature and extent of potential petroleum (in the form of released diesel fuel) related contamination in the surface and near-surface soil at selected areas of the site; and the analytical results and recommendations of Koa’s environmental professional are documented in this report.
The Phase II ESA included the collection of multi-incremental (MI) soil samples from two decision units (DUs) defined at the site and subsequent laboratory analysis of the soil samples. The MI soil samples consisted of multiple, regularly-spaced increments that were collected from between the ground surface and 1-foot bgs within DU 01, and from between the top and the bottom at regularly-spaced intervals within each stockpile of material located at DU 02. The soil samples were submitted to an offsite analytical laboratory under standard chain-of-custody procedures and were analyzed for the RCRA 8 metals as well as for total petroleum hydrocarbons (TPH) in the diesel range organics (DRO) and the oil range organics (ORO) fraction of TPH compounds.
The results of these soil samples were compared to screening levels, which consisted of the 2017 Tropical Pacific Environmental Screening Levels (TPESLs) including a comparison to background concentrations for certain metals. None of the detected concentrations of RCRA 8 metals exceed their background concentrations. None of the detected concentrations of metals or TPH in the DRO and ORO fractions exceeded TPESLs based on residential or commercial/ industrial land use; which indicates that the soil materials in question and in their present condition do not pose a direct exposure human health concern.
Based on the results of the Phase II ESA; no further action or investigation at these targeted areas for these COPCs in soil is recommended at this time.