Remedial Investigation, IR Site 31, Defense Fuel Support Point (DFSP), San Pedro, CA.

This task order includes the preparation of Planning Documents, performance of associated Remedial Investigation field work, and preparation of the Remedial Investigation Report for Site 31.

The objective of this project was to conduct a Remedial Investigation (RI) at Installation Restoration Program (IRP) Site 31, Central Ravine at Defense Fuel Support Point (DFSP) San Pedro, California. The purpose of the RI is to further define the nature and extent of contamination at the site and make recommendations for further action, if necessary.

IRP Site 31 is located on approximately 9.4 acres in the northwest portion of the facility. IRP Site 31 occupies the northwest portion of the Central Ravine that bisects the DFSP San Pedro property and trends west to east through the center of the property. Between 1972 and 1984 the Central Ravine occasionally received construction debris and various uncontrolled wastes. The fill contents are primarily construction debris (concrete, asphalt, brick, and rebar) and miscellaneous surface debris (metal debris, pallets, paint cans, refuse, and a drum) primarily in the northern portion of the ravine. Construction debris is exposed along the embankments of the partially filled ravine. An earthen berm (approximately 20 feet tall) is located at the eastern edge of the ravine, downstream of the partially filled ravine. The site is located in a geologically complex area with folding and faulting affecting groundwater movement. Additionally, the site is a steep sided, heavily vegetated ravine making access to the sampling areas at the base of the ravine difficult.

Field activities included collecting a total of 39 soil samples from 13 soil borings within the ravine and the installation of three groundwater monitoring wells – one upgradient of IRP Site 31 and two downgradient of the disposal area. Groundwater samples were collected from the three new and four existing groundwater monitoring wells in two semi-annual sampling events.

Following completion of the field activities, an RI Report was prepared that documented the results of the remedial investigation, identified the nature and extent of the contamination encountered at the site, and provided recommendations for conducting a feasibility study, if necessary. The RI report also included an update to the existing human health and ecological risk assessments, an evaluation of the fill thickness within the ravine, and all other data required to support the preferred remedial alternative for the site.