Township Council Meeting — Packet

Bureau of Case Assignment &Initial Notice Re: Vapor Intrusion Investigation Report West Orange DPW 25 Lakeside Ave April 2023 Page 10 Concentrations of trichloroethene were reported above the Non-Residential and Residential SoilGas Screening Levels (SGSL) in samples SSAS-2, SSSG-3, SSSG-5 and SSSG-6. Based on the assessment of the results, trichloroethene is found in the sub-slab soil gas (SSSG) samples but below the Non-Residential Indoor Air Remediation Standards in the indoor air (IA) samples. In this case, the Mitigation Decision Matrix indicates that sampling results of SSSG that are greater than the SGSL but at or less than 10 times the Non-Residential SGSL, long-term monitoring (LTM) is recommended. The following details the recommended LTM schedule: First year LTM: 1. Annual inspection of building 2. Sampling of IA during heating season. After first year LTM: 1. Annual inspections of building 2. Sampling of IA every five years Table 2 presents the analytical results of the sub-slab gas samples. Appendix 2 presents the Indoor Air, Ambient Air and Sub Slab Gas Laboratory Analytical Results, QA/QC Documents and Chain of Custody Forms. P:\I00 CME7\West Orange\DPW 25 Lakeside Ave\VI Investigation 2023\VI letter Report\VI Letter Report - DPW West Orange - April 2023.docx