The findings of the test pit and rotosonic investigations indicate that additional excavation is warranted to remove the AUES debris that was encountered in soil west, north, and east of the Public Safety Building footprint. The goal of the PSB slope investigation was to determine the extent of continuous AUES debris extending from the PSB excavation sidewalls. An area of continuous AUES debris was indicated to the west (approximately 12 feet from the former PSB foundation), to the east (approximately 16 feet from the former PSB foundation), and to the north (approximately 15 feet from the former PSB foundation). This area also corresponds to soil benches 4 and 5, where AUES debris was encountered during the excavation in 2019 ... [The proposed soil and AUES debris excavation area] would involve the excavation and removal of an estimated in-place volume of 720 cubic yards of soil and AUES debris ... Prior to excavating a specific area, a UXO Tech III will sweep the planned excavation area with a magnetometer ... Any identified MEC items or intact AUES items will be handled in accordance with the Low Probability Contingency Plan [pg. 15].
Weston Solutions, Inc.
PSB Slope Investigation Report
June 23, 2021 (pgs. 10 & 11)
USACE sent out a "Request of Proposal" dated July 21 2021 to complete excavation of AUES debris east, north and west of the former PSB foundation. Proposal was submitted on 8 September 2021. The proposed soil to be excavated is presented in the [slide below]; the area is based on the test pit and Rotosonic soil borings completed at the PSB site in April 2021. To safely conduct the soil slope excavation north of the former PSB foundation, a soil retaining wall is recommended ... The planned upslope excavation at RS-04 would be conducted using a slide rail shoring system.
Based on the investigation results, USACE determined the scope of work to excavate the extent of AUES debris identified. Once funding has been obtained and the work awarded, additional plans will be required before re-starting the soil remediation work. This will entail a delay of many months before the work is awarded and the required planning documents are prepared and approved. Slope Soil Removal not expected to begin until winter/spring 2022.
Spring Valley RAB
PowerPoint Presentation
November 9, 2021 (pgs. 21 & 23)
