From: Soren Hill

Sent: Tue Oct 10 14:48:48 2023

To: PUGH Mark * DEQ

Cc: Chuck Esler; ryounger@terwilligerplaza.com; Tanya Battye

Subject: Former 5 Star Cleaners

Importance: Normal

Attachments: image001.jpg; Tables.pdf; July 2023 O& M Field Report.pdf; August 2023 O& M Field Report.pdf; September 2023 O& M Field Report.pdf;

Mark,

This email provides a quarterly progress report for the former Five Star Cleaners property at 2305 SW 6th Avenue. This progress report is being submitted for the third quarter of 2023, on behalf of Pacific Skyline Holdings II, LLC.

Actions taken during the previous 3 months:

Monthly O&M visits by Farallon were conducted on July 18, August 31, and September 22, 2023. The vapor recovery wells and collection pits operated continuously during this time. Monthly O&M field reports are attached.

· Concentrations of volatile organic compounds (VOCs) were measured using a photoionization detector (PID) at monitoring points at the vapor collection system, sub-slab vapor pins, and vapor recovery wells. PID readings are summarized in Table 1 (attached).

· Differential pressures across the concrete slab floor were measured using a hand-held vacuum gauge. Differential pressure readings are summarized in the O&M field reports.

Semi-annual vapor samples and indoor air samples were not collected during the previous 3 months. Consistent with the Operation and Maintenance Manual, the second round of semi-annual samples will be collected in October 2023. The results of historical air sampling are summarized in Tables 2 and 3 (attached).

Summary of sampling, test results, and any other data generated or received during the previous 3 months:

• * Monthly O&M field reports are attached. PID readings are tabulated in Table 1 (attached).
• * PID readings from vapor collection system exhaust were as follows:
  • * VOCs were detected in the Pits Exhaust from the vapor collection pits at the following levels: 0.9 parts per million (ppm) in July 2023, 0.4 ppm in August 2023, and 1.1 ppm in September 2023.
  • * VOCs were detected in the Pre-Carbon Effluent from the vapor recovery wells at the following levels: 12.8 ppm in July 2023, 14.96 ppm in August 2023, and 10.0 ppm in September 2023.
  • * VOCs were detected in the Post-Carbon Effluent from the vapor recovery wells at a level of 0.4 ppm in July 2023. VOCs were not detected in the Post-Carbon Effluent from the vapor recovery wells in August or September 2023.
• * Positive pressure was measured at the exhaust stack for the vapor pits collection system In July, August, and September 2023, indicating the system is functional.
• * A vacuum was observed at the carbon inlet for the recovery wells in July, August, and September 2023, indicating the system is functional.
• * A pressure differential ranging from -0.005 to -0.065 inches of water column was measured at vapor points VP-5 through VP-8 during July, August, and September 2023 monitoring, except July 2023 when no pressure differential was measured at VP-5. Readings from the third quarter’s O&M indicate that the system is functional.

A description of any problems experienced during the previous three months and actions taken to resolve them:

• * The vacuum collection pit piping was checked for the accumulation of water during the September O&M event and a trace amount of water was removed from the piping using a peristaltic pump.

Actions scheduled in the next 3 months:

• * Monthly O&M visits will be conducted in October, November, and December 2023.
• * Semi-annual vapor sampling and indoor air sampling will be conducted in October 2023 (see O&M plan for sampling details).
• * In the event heavy rainfall occurs in the upcoming months, the piping system will be checked for water accumulation.

If DEQ has questions about the information provided in this progress report, please do not hesitate to contact us.

Best regards,