Wolfe Ranch Cattle Dipping Vat Arsenic Remediation
The approximate 2,261-acre site is located in largely rural south-central St. Johns County, Florida. ESI conducted a Phase I Environmental Site Assessment (ESA), Phase II ESA and Interim Remedial Action (IRA), as well as natural community, protected species, wetlands and archeological studies for the site.
The site comprises primarily undeveloped farm/pastureland occupied in three separate locations on the Ranch portion of the site by associated barns, silos, cattle pens and other small structures, which appeared to have been abandoned for several years.
Historically, this portion of the site had been used as a cattle ranch since the 1940s, with ranch operations ceasing in the late 1990s, except for leasing of portions of the pastureland to others. Past use of petroleum underground storage tanks, oils and potentially hazardous substances, and a cattle dipping vat were identified.
The Phase I ESA was conducted in conformance with the scope and limitations of ASTM Standard Practice E 1527-00 and recommended further assessment of the abandoned cattle dipping vat vicinity. ESI performed a concurrent Phase II ESA and Contamination Assessment in order to determine the presence or absence of contaminants typically associated with cattle dipping vats and delineated an arsenic plume. The estimated area of impact was approximately 95-feet by 30-feet with a maximum of 6-feet below level surface (bls) in depth. Maximum concentrations above applicable State of Florida SCTLs for arsenic and 4,4’-DDT were 17 mg/kg or parts per million (ppm) and 13.2 ppm, respectively. Maximum concentrations above applicable Florida groundwater standards or criteria for arsenic were 47 ug/l or parts per billion (ppb). Approximately 400 tons of soil were delineated in the Phase II ESA and subsequent Contamination Assessment with concentration levels above residential and commercial/industrial direct contact, but below the leachability to groundwater criteria in Chapter 62-777, F.A.C.
The purpose of the IRA was to actively remediate the impacted soil source material and thereby remediate groundwater to concentrations below either applicable Florida regulatory criteria or laboratory method detection limits (BDL). Interim Remedial Action was completed to excavate the remnants of the cattle dipping vat and identified impacted soils, transport the soils to an off-site disposal facility, and conduct post-excavation confirmatory sampling. An IRA report was prepared and submitted to Florida Department of Environmental Protection (FDEP) documenting the excavation and removal of approximately 420 tons of arsenic-impacted soils, as well as post-excavation soil and groundwater confirmation sampling and analysis, and requesting No Further Action (NFA) Status for the site. Subsequently, a Site Rehabilitation Completion Order (SRCO) was issued, relieving the property owner of obligation to conduct additional assessment or remediation.