Chemical analyses and biological response data were used to assess the efficacy of a field-scale hyperfiltration unit in the removal of polycyclic aromatic hydrocarbons (PAHs) and other organic compounds from creosote- and pentachlorophenol (PCP)-contaminated ground water recovered from the former American Creosote Works in Escambia County, Pensacola, Florida. The hyperfiltration unit consisted of 4 modules containing porous stainless steel tubes which were coated with a formed-in-place zirconium hydrous oxide-polyacrylic acid (ZOPA) membrane. A 5-fold concentration of the feedwater (80% volume reduction) with up to 97% removal of high molecular weight PAHs was achieved during pre-demonstration and field-demonstration runs of the hyperfiltration unit. Toxicological and teratogenic data for embryonic inland silversides, Menidia beryllina, indicated that 100, 10 and 1% solutions of the ground water sample used in the pre-demonstration run caused statistically significant (p < or - 0.05) biological responses when compared to controls. Permeates from both runs, diluted to 1%, met the pre-condition of non-toxic responses in 48h tests with Ceriodaphnia dubia. Meeting this requirement allowed for discharge of diluted permeate into the county's sanitary sewerage collector system.