The transformation rate of 1,2‐dibromo‐3‐chloropropane (DBCP) was determined in phosphate buffer solution, in groundwater, and in groundwater/aquifer solid slurries from ambient temperatures to 72 °C. From the disappearance data, the apparent Arrhenius constants for DBCP transformation were calculated and found to decrease in Ea with temperature from 19.2 (±2.4) kcal mol−1 in the 55 to 72 °C range to 12.5 (±1.8) kcal mol−1 in the 21 to 55 °C range. Low sorption values were an indication that sorption does not play a major role in the aquifer being studied. No significant difference in the disappearance rates was observed in the buffer solution (corrected for buffer effects) and in groundwater with and without solids added. However, in the phosphate buffer solution, dehydrohalogenation appeared to be the favored transformation process in contrast to the groundwater systems where hydrolysis seemed to predominate. This apparent influence of dissolved constituents or temperature on transformation mechanism or rate may restrain the use of direct extrapolation of data between systems. Applying the transformation data from this study to median field parameters, a DBCP half‐life of 6.1 yr was calculated for typical groundwater conditions in California (pH 7.8 and 21.1 °C).

A laboratory study was conducted to determine the influence of pH on the distribution of arsenic (As), barium (Ba), chromium (Cr), and lead (Pb) in three different oil and gas well drilling fluid wastes. Samples were obtained from disposal pits and equilibrated in the laboratory under controlled conditions of pH. A sequential extraction procedure was then used to fractionate the selected elements into the fractions of aqueous, KNO3‐extractable, H2O‐extractable, NaOH‐extractable, EDTA‐extractable, and HNO3‐extractable phases. The chemical fractions present at each pH were then compared, thus providing insight into the potential of mobilization of As, Ba, Cr, and Pb into ground‐ or surface waters. The majority of each of the elements studied was found in the NaOH‐extractable, EDTA‐extractable or HNO3‐extractable fractions except for one waste which contained a major portion of the total barium in the KNO3‐extractable fraction. Generally, decreasing pH caused a shift from the more stable HNO3‐extractable fraction toward less stable EDTA‐extractable, NaOH‐extractable, or KNO3‐extractable fractions. In no case was there a substantial release to the aqueous phase with changing pH. The significance of these results is that with pH changes to be expected in the natural environment there is not likely to be a major release of As, Ba, Cr, and Pb from drilling fluid waste disposal pits. The lower pH values (< 4) which might produce some impact are unlikely to occur in the environment because the wastes themselves have a large neutralizing capacity.

Double-vial radiorespirometry was used to estimate the biodegradation rates of 14C-labeled phenol in a landfill leachate and a secondary treated domestic wastewater. Rates were found to be comparable for each material at each of the three concentrations tested. Sewage microorganisms immediately began biodegrading the [14C]phenol; landfill leachate microorganisms required a lag period before maximum biodegradation of the [14C]phenol. The apparent rate of [14C]phenol biodegradation was 2.4 times faster in the sewage than in the landfill leachate. Double-vial radiorespirometry was shown to be an effective method for screening biodegradation rates in aquifers.

Regulators often require that Total Petroleum Hydrocarbons (TPH) be measured and set TPH clean-up criteria for soils impacted by crude oil. However, the lack of a standardized, scientifically defensible procedure for interpreting TPH has resulted in the establishment of arbitrary criteria ranging from 100 to 20,000 ppm (mg/kg) TPH in soil. In the past, TPH regulations and guidance have not considered a technical approach to addressing risk to human health. Recent efforts by the TPH Criteria Working Group (TPHCWG) have established human-health Risk-Based Screening Levels (RBSLs) for refined petroleum products. RBSLs for crude oils and exploration/ production wastes are being addressed by a joint industry effort through Petroleum Environmental Research Forum Project 97-08. The TPHCWG methodology was modified to include the high molecular weight compounds that are present in many crude oils. As part of the project, 48 crude oils were characterized for aliphatic and aromatic hydrocarbon content within equivalent carbon number ranges. Appropriate toxicity, fate, and transport values were determined for compounds greater than carbon number C35. Upon project completion, a risk-based screening method will be available for evaluating TPH at upstream sites. This method can be incorporated into an upstream version of a Risk-Based Corrective Action Plan (RBCA).

Water based drilling muds typically contain clays, barite, lime, caustic soda and other chemicals, such as polymers. Land disposal of these wastes raises the possibility of groundwater pollution which can be abated if the waste is stabilized either by chemical reaction or by solidification through some form of cementation. Many ASTM high-calcium (Class C) fly ashes are cementitious and thus may be useful in stabilization of drilling mud. The basic idea is to stabilize the clay-containing muds using the model of soil and roadbed stabilization with high-calcium fly ash [1]. Fly ash that is not utilized is considered to be a solid waste, so this application would would actually constitute codisposal of two wastes.