A study of subsurface vapor intrusion from exploration & production waste

Abstract

Expanding city growth is causing the inhabitants of Louisiana to move further into rural areas. Abandoned oil and gas production sites are being used for residential and light commercial purposes. This thesis will attempt to determine if known benzene levels in Exploration and Production (E&P) waste will be harmful to human health via subsurface vapor intrusion into the newly developed residential and light commercial structures. Louisiana does not currently regulate benzene during the closure of pits that contained E&P waste. Current pit closure techniques warrant testing for benzene Based on current Louisiana legislation, benzene contamination of groundwater is currently the most protected human exposure route to benzene from E&P waste. Indoor air emissions from benzene in E&P waste in the soil must be studied to determine the risks associated to developing residential properties on abandoned exploration and production sites. Exploration and Production waste is described in Louisiana Administrative Code (LAC) 43:Part XIX. Section 129.B as “drilling wastes, salt water, and other wastes associated with the exploration, development, or production of crude oil or natural gas wells and which is not regulated by the provisions of, and, therefore, exempt from the Louisiana Hazardous Waste Regulations and the Federal Resource Conservation and Recovery Act.” The constituents of concern tested in soil and groundwater, which are currently regulated by Statewide Order 29-B for pit closures are chlorides, petroleum hydrocarbons, and metals. Previous studies of E&P waste are used to determine the characteristics, concentration, and potential harm from benzene to human health found in E&P wastes. These studies were funded by the State and are used in this thesis to provide Louisiana related data. These previous studies of E&P waste are also used as baseline references for known benzene concentrations in E&P waste. A risk assessment outline established by F.B. Thomas in combination with the calculations provided by the Johnson and Ettinger Model (1991) for Subsurface Vapor Intrusion into Buildings are used to estimate the risk of the indoor air exposure to benzene vapors remaining in the soil from closed E&P waste pits.