The North Cavalcade Street site covers 21 acres in Houston, Texas. Houston Creosoting Company operated a wood-preserving facility there from 1946 to 1961, leaving soil and groundwater contaminated with creosote and related hazardous chemicals. EPA added the site to the National Priorities List (NPL) in June 1986. NPL is the federal government's list of the most serious uncontrolled hazardous waste sites in the country.
More than 50 chemicals have been identified as contaminants of concern. Groundwater in both shallow and intermediate aquifers contains benzene, toluene, xylene, naphthalene, arsenic, phenol, and various polycyclic aromatic hydrocarbons (PAHs). PAHs are a group of chemicals that form when organic materials burn or break down. Soil contamination includes arsenic, lead, chromium, copper, zinc, benzene, and multiple PAHs including benzo[a]pyrene and anthracene.
EPA has organized cleanup into three operable units covering the shallow aquifer, soil, and the intermediate aquifer. Key actions include capping and containment of contaminated soils, completed in 2011, and in-place stabilization of groundwater source areas, finished in 2010. Dense non-aqueous phase liquids (DNAPLs), which are heavy contaminant liquids that sink in groundwater, were removed from monitoring wells between 2011 and 2012. A permanent monitoring well network was installed between 2010 and 2011. Institutional controls restrict property use and prevent groundwater extraction. Physical construction of the cleanup is complete across the entire site. Operation and maintenance work and groundwater monitoring are ongoing. A remedial investigation for the intermediate aquifer began in August 2022 and is estimated to finish between December 2026 and February 2027.
EPA's June 2023 Five-Year Review found the remedy protective of human health and the environment in the short term. Human exposure is currently under control, and contaminated groundwater migration is stabilized with no unacceptable discharge to surface water. To stay protective over the long term, EPA still needs to evaluate how vapors could enter buildings through soil gas, map the full extent of DNAPL and dissolved contamination, reassess which contaminants need continued monitoring, and finalize required institutional controls. The site is estimated to be ready for full anticipated reuse between May and July 2028. Currently, the northern 10 acres outside the containment cap are available for reuse, and one on-site business is already operating.
Community members can read the full 2023 Five-Year Review Report online or in person at the Houston Central Library Julia Ideson Building, Government Documents Area, 550 McKinney Street, Houston, TX 77002 (phone 832-393-1662). For site-specific questions, contact the EPA Community Involvement Coordinator. The Texas Commission on Environmental Quality (TCEQ) also maintains contacts for the site.
