From: Lisa Thompson
Sent: Thu Jan 15 13:56:37 2026
To: PUGH Mark * DEQ
Cc: Andie Fitzgerald; Suzy Stumpf
Subject: Former Five Star Cleaners (2305 SW 6th Avenue) – Q4 2025 Quarterly Progress Report
Importance: Normal
Attachments: image001.png; Figure 2_SitePlan.pdf; Q4 2025 Tables.pdf; Q4 2025 O& M Inspection Forms and Field Notes.pdf; ALS Indoor Air 2530336-Report_2025-11-04.pdf; Pace System Air L1911511-Report_2025-11-03.pdf;
Mark,
This email provides a quarterly progress report for the former Five Star Cleaners property at 2305 Southwest 6th Avenue (DEQ ECSI Site ID No. 6276) (herein referred to as the Site). This progress report is being submitted for the fourth quarter of 2025, on behalf of Pacific Skyline Holdings II, LLC.
Actions taken during the previous 3 months:
- * Farallon conducted monthly operation and maintenance (O&M) visits to document the Site’s Vapor Collection System performance on October 23, November 19, and December 18 , 2025. Monthly O&M activities included monitoring the following parameters:
- * Volatile organic compounds (VOCs) vapor concentrations as measured using a hand-held photoionization detector (PID) were screened at select monitoring points, including at the vapor collection system, subslab vapor points, and vapor recovery wells. PID readings are summarized in Table 1 (attached).
- * Differential pressures were measured at the subslab vapor points (VP-5 through VP-8) using a hand-held vacuum gauge (Figure 2). Differential pressure readings are summarized in Table 2 (attached).
- * Semiannual air samples were collected from the influent (pre-carbon) and effluent (post-carbon) lines of the vapor granular activated carbon treatment vessels using Summa canisters on October 23, 2025. The samples were submitted to Pace Analytical laboratories for analysis using U.S. Environmental Protection Agency (EPA) Method TO-15 for VOCs, including but not limited to tetrachloroethene (PCE) and trichloroethene (TCE). Analytical results for PCE, TCE, cis- and trans-1,2-dichloroethene, and select petroleum hydrocarbons collected pre- and post-carbon are shown in Table 3 (attached). The analytical report is also attached.
- * Indoor and outdoor ambient air samples were collected using Radiello badges between October 16 and 23, 2025. The samples were submitted to ALS Environmental laboratories for analysis for PCE and TCE by EPA Method TO-17. None of the indoor air samples exceeded the State of Oregon Department of Environmental Quality Risk-Based Concentrations Table, revised May 2018, for Occupational for PCE or TCE. Ambient air analytical results are shown in Table 4 (attached). The analytical report is also attached.
Summary of monitoring data and sample analytical results for the previous 3 months:
Monthly O&M field reports are attached. PID readings are tabulated in Table 1, and vacuum and pressure readings are tabulated in Table 2 (attached).
- * PID readings from vapor collection system exhaust were as follows:
- * VOCs were not detected in the Pits Exhaust from the vapor collection pits during the October, November, or December 2025 O&M visits.
- * VOCs were detected in the Pre-Carbon Effluent from the vapor recovery wells at concentrations of 11 part per million (ppm) in October, 24 ppm in November, and 49 ppm in December 2025.
- * VOCs were not detected in the Post-Carbon Effluent from the vapor recovery wells during the October, November, or December 2025 O&M visits.
- * Positive pressure was measured at the exhaust stack for the vapor pits collection system in October, November, and December 2025, confirming air flow and that the fan is operational.
- * A vacuum was observed at the carbon inlet for the recovery wells in October, November, and December 2025, confirming air flow and that the fan is operational.
- * A vacuum ranging from 0.003 to 0.008 inches of water column was measured at vapor points VP-5 through VP-7 during October through December 2025 monitoring. Vacuum was not measurable at vapor point VP-8 during October through December 2025 monitoring. It is suspected that the lack of measurable vacuum is attributed to water accumulation in the subslab vapor collection pit piping that is not accessible. However, the semi-annual indoor air data demonstrates that even if the SSDS effectiveness is reduced proximate to VP-8 the potential vapor intrusion to indoor air exposure pathway is incomplete. Vacuum measurements from the remaining observation points confirm a negative pressure field beneath the foundation slab.
A description of any problems experienced during the previous 3 months and actions taken to resolve them:
- * The subslab vapor collection pit piping was checked for the accumulation of water during the October, November, and December 2025 O&M events. Accumulated water removed from the subsurface piping system ranged from approximately 1/2 to 4 cups. Water removed from the subsurface piping system is collected and stored on-Site in a lidded 5-gallon bucket pending appropriate analytical testing and disposal.
Actions scheduled in the next 3 months:
- * Conduct monthly O&M visits in January, February, and March 2026.
- * In the event significant rainfall occurs in the upcoming months, check the piping system for water accumulation.
If you have any questions about the information provided in this progress report, please do not hesitate to contact us.
Project Manager: Lisa Thompson, P.E., Associate Engineer
Farallon Consulting, L.L.C.
Phone: (425) 395-4636
Email: lthompson@farallonconsulting.com
Technical Contacts: Lisa Thompson, P.E., Associate Engineer
Farallon Consulting, L.L.C.
Phone: (425) 395-4636
Email: lthompson@farallonconsulting.com
Suzy Stumpf, P.E., Principal Engineer
Farallon Consulting, L.L.C.
Phone: (303) 489-1032
Email: sstumpf@farallonconsulting.com
Regards,
This correspondence contains confidential or privileged information from Farallon Consulting and may be "Attorney-Client Privileged" and protected as "Work Product." The information contained herein is intended for the use of the individual or party named above. If you are not the intended recipient, note that any copying, distribution, disclosure, or use of the text and/or attached document(s) is strictly prohibited. If you have received this correspondence in error, please notify us immediately. Thank you.
