ARCHIVED REPORTS_XR0011359 - Laserfiche WebLink

Home Browse Search

i conditions present at the Disco location, target levels of BTEX and TPH-Gas are { nondetectable and 10 mg/kg, respectively. Remedial Technologies Potentially applicable technology types and process options expected to be effective in achieving the remedial objectives in soil and groundwater were identified and evaluated (Figure 4-1). Also included are screening comments with respect to the effectiveness, implementability, and relative cost of each of the process options for the chemical compounds and conditions at the property. Effectiveness is an estimate of how well each process option will perform in handling the estimated volume of waste material and in reducing contamination or controlling mobility. Implementability includes both construction considerations and the feasibility of implementing each process option in order to eliminate those that would be unworkable or too difficult to permit at the .property. The initial cost screening was based on engineering judgement as to whether costs were high, low, or moderate relative to other process options of the same technology type. + As a result of the technology screening for soils and groundwater shown on Figure 4-1, technology options expected to be the most cost-effective were selected for developing remedial alternatives. Technology Descriptions Process Options for Unsaturated Soils As discussed in Section 3 of this report, petroleum hydrocarbons occur in the unsaturated soil within the vertical boundaries. of the former tank pit. Affected soils in this area occupy a zone about 20 feet thick,above the groundwater table, between 55 and 75 feet bgs. The depth at which these petroleum hydrocarbons occur in the soil make excavation impractical. Therefore, the remediation options chosen for unsaturated soil are the in situ techniques of sparging and bioremediation. Sparging. Sparging is a method of introducing air, and thus oxygen, into the subsurface. Blowers installed in wells inject air below the water table. Sparging allows for oxygen to penetrate a specific and localized area above and below the water table. This introduction of oxygen will stimulate aerobic biodegradation of petroleum compounds.. In Situ Bioremediation. In situ bioremediation is commonly used for treating petroleum products in soil and groundwater. Biological degradation occurs naturally in the environment, but with the addition of nutrients in an aerobic environment, biodegradation can be greatly enhanced. The technology involves adding nutrients such as nitrogen and phosphorus, and oxygen to saturated soil and groundwater through sF03160 \RP1007.51 4-3