Environmental Engineering and Remediation
Site Inspections and Investigations

Investigation of Off-Site Downgradient Private Drinking Water Wells for Per-fluorinated Compounds (PFCs) or Per- and Polyfluoroalkyl Substances (PFAS)

Former Crows Landing Naval Air Station, Crows Landing, CA

The overall objective for this project was to identify and sample private drinking water wells for PFAS located within 1-mile downgradient of the Crows Landing property line. The goal of this investigation was to confirm or deny potential PFAS impacts exceeding U.S. Environmental Protection Agency (U.S. EPA) Lifetime Health Advisory levels in downgradient drinking water wells. GCE performed this project under subcontract.

After identifying and verifying private properties with potential drinking water wells (within 1-mile downgradient), GCE obtained private property owner information and provided the information to the Navy for development of access agreements. GCE performed an offsite receptor evaluation by reviewing prior Navy work, various online potable water well databases, State of California and Stanislaus County water management district records, and other resources to verify property owner information for potential potable wells for investigation. Once completed access agreements were received, GCE coordinated with the Navy and individual property owners to determine dates and times for sample collection.

Before fieldwork commenced, GCE prepared addenda to an existing PFAS Sampling and Analysis Plan (SAP) and Quality Assurance Project Plan (QAPP), as well as addenda to the current Accident Prevention Plan (APP) and Safety and Health Plan (SSHP).
GCE coordinated with the Navy Marine Corps Public Health Center (NMPHC) to prepare a Fact Sheet and distribute it through targeted mailing. GCE advertised and hosted two (2) public meetings to provide information to the property owners, as well as two (2) informational meetings to explain the intent of the PFAS sampling.

Samples of the private drinking water wells were collected from an existing valve or faucet head, and not at the wellhead. A single round of drinking water samples was collected and analyzed by EPA Method 537.1.1, which included 18 perfluoroalkyl acids, including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA) and perfluorobutanesulfonic acid (PFBS).
A Technical Memorandum was prepared at the conclusion of the field work.